* Re: [PATCH v4 00/14] ima: introduce IMA Digest Lists extension
From: Roberto Sassu @ 2019-06-25 12:57 UTC (permalink / raw)
To: zohar, dmitry.kasatkin, mjg59
Cc: linux-integrity, linux-security-module, linux-fsdevel, linux-doc,
linux-kernel, silviu.vlasceanu
In-Reply-To: <9029dd14-1077-ec89-ddc2-e677e16ad314@huawei.com>
On 6/17/2019 8:56 AM, Roberto Sassu wrote:
> On 6/14/2019 7:54 PM, Roberto Sassu wrote:
>> This patch set introduces a new IMA extension called IMA Digest Lists.
>>
>> At early boot, the extension preloads in kernel memory reference digest
>> values, that can be compared with actual file digests when files are
>> accessed in the system.
>>
>> The extension will open for new possibilities: PCR with predictable
>> value,
>> that can be used for sealing policies associated to data or TPM keys;
>> appraisal based on reference digests already provided by Linux
>> distribution
>> vendors in the software packages.
>>
>> The first objective can be achieved because the PCR values does not
>> depend
>> on which and when files are measured: the extension measures digest lists
>> sequentially and files whose digest is not in the digest list.
>>
>> The second objective can be reached because the extension is able to
>> extract reference measurements from packages (with a user space tool) and
>> use it as a source for appraisal verification as the reference came from
>> the security.ima xattr. This approach will also reduce the overhead as
>> only
>> one signature is verified for many files (as opposed to one signature for
>> each file with the current implementation).
>>
>> This version of the patch set provides a clear separation between current
>> and new functionality. First, the new functionality must be explicitly
>> enabled from the kernel command line. Second, results of operations
>> performed by the extension can be distinguished from those obtained from
>> the existing code: measurement entries created by the extension have a
>> different PCR; mutable files appraised with the extension have a
>> different
>> security.ima type.
>>
>> The review of this patch set should start from patch 11 and 12, which
>> modify the IMA-Measure and IMA-Appraise submodules to use digest lists.
>> Patch 1 to 5 are prerequisites. Patch 6 to 10 adds support for digest
>> lists. Finally, patch 13 introduces two new policies to measure/appraise
>> rootfs and patch 14 adds the documentation (including a flow chart to
>> show how IMA has been modified).
>>
>> The user space tools to configure digest lists are available at:
>>
>> https://github.com/euleros/digest-list-tools/releases/tag/v0.3
>>
>> The patch set applies on top of linux-integrity/next-queued-testing
>> (73589972b987).
>>
>> It is necessary to apply also:
>> https://patchwork.kernel.org/cover/10957495/
>
> Another dependency is:
>
> https://patchwork.kernel.org/cover/10979341/
>
> Roberto
I uploaded this patch set and all the required dependencies to:
https://github.com/euleros/linux/releases/tag/ima-digest-lists-v4
It should be easy to test. Let me know if you have questions about the
installation.
Mimi, do you have any thoughts on this version?
Thanks
Roberto
--
HUAWEI TECHNOLOGIES Duesseldorf GmbH, HRB 56063
Managing Director: Bo PENG, Jian LI, Yanli SHI
^ permalink raw reply
* Re: [PATCH V34 28/29] efi: Restrict efivar_ssdt_load when the kernel is locked down
From: Ard Biesheuvel @ 2019-06-25 15:00 UTC (permalink / raw)
To: Matthew Garrett
Cc: James Morris, linux-security-module, Linux Kernel Mailing List,
linux-api, Matthew Garrett, linux-efi
In-Reply-To: <20190622000358.19895-29-matthewgarrett@google.com>
On Sat, 22 Jun 2019 at 02:05, Matthew Garrett <matthewgarrett@google.com> wrote:
>
> efivar_ssdt_load allows the kernel to import arbitrary ACPI code from an
> EFI variable, which gives arbitrary code execution in ring 0. Prevent
> that when the kernel is locked down.
>
> Signed-off-by: Matthew Garrett <mjg59@google.com>
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Cc: linux-efi@vger.kernel.org
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
> drivers/firmware/efi/efi.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> index 55b77c576c42..9f92a013ab27 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -31,6 +31,7 @@
> #include <linux/acpi.h>
> #include <linux/ucs2_string.h>
> #include <linux/memblock.h>
> +#include <linux/security.h>
>
> #include <asm/early_ioremap.h>
>
> @@ -242,6 +243,11 @@ static void generic_ops_unregister(void)
> static char efivar_ssdt[EFIVAR_SSDT_NAME_MAX] __initdata;
> static int __init efivar_ssdt_setup(char *str)
> {
> + int ret = security_locked_down(LOCKDOWN_ACPI_TABLES);
> +
> + if (ret)
> + return ret;
> +
> if (strlen(str) < sizeof(efivar_ssdt))
> memcpy(efivar_ssdt, str, strlen(str));
> else
> --
> 2.22.0.410.gd8fdbe21b5-goog
>
^ permalink raw reply
* Re: [PATCH] structleak: disable BYREF_ALL in combination with KASAN_STACK
From: Ard Biesheuvel @ 2019-06-25 15:01 UTC (permalink / raw)
To: Kees Cook
Cc: Arnd Bergmann, Andrey Ryabinin, Alexander Potapenko,
Dmitry Vyukov, kasan-dev, Alexander Popov, James Morris,
Serge E. Hallyn, Masahiro Yamada, LSM List,
Linux Kernel Mailing List
In-Reply-To: <201906221324.C08C1EF@keescook>
On Sat, 22 Jun 2019 at 22:26, Kees Cook <keescook@chromium.org> wrote:
>
> On Fri, Jun 21, 2019 at 03:50:02PM +0200, Ard Biesheuvel wrote:
> > On Fri, 21 Jun 2019 at 15:44, Arnd Bergmann <arnd@arndb.de> wrote:
> > > One pattern I have seen here is temporary variables from macros or
> > > inline functions whose lifetime now extends over the entire function
> > > rather than just the basic block in which they are defined, see e.g.
> > > lpfc_debug_dump_qe() being inlined multiple times into
> > > lpfc_debug_dump_all_queues(). Each instance of the local
> > > "char line_buf[LPFC_LBUF_SZ];" seems to add on to the previous
> > > one now, where the behavior without the structleak plugin is that
> > > they don't.
>
> Ewww.
>
> > Right, that seems to be due to the fact that this code
> >
> > /* split the first bb where we can put the forced initializers */
> > gcc_assert(single_succ_p(ENTRY_BLOCK_PTR_FOR_FN(cfun)));
> > bb = single_succ(ENTRY_BLOCK_PTR_FOR_FN(cfun));
> > if (!single_pred_p(bb)) {
> > split_edge(single_succ_edge(ENTRY_BLOCK_PTR_FOR_FN(cfun)));
> > gcc_assert(single_succ_p(ENTRY_BLOCK_PTR_FOR_FN(cfun)));
> > }
> >
> > puts all the initializers at the beginning of the function rather than
> > inside the scope of the definition.
>
> Do you see a sane way to improve this? I hadn't noticed that this
> actually moved it up to the start of the function. :(
>
Not from the top of my head, and I won't be able to spend any time on
this in the near future, unfortunately.
^ permalink raw reply
* Re: [PATCH v3 21/24] Audit: Store LSM audit information in an lsmblob
From: Casey Schaufler @ 2019-06-25 15:30 UTC (permalink / raw)
To: Paul Moore, John Johansen
Cc: casey.schaufler, James Morris, linux-security-module, selinux,
keescook, penguin-kernel, Stephen Smalley, Eric Paris,
linux-audit, casey
In-Reply-To: <CAHC9VhSSMjCdT8gfB03gh8VvJngTHnsUsDCpseMUiEPQM9z_FQ@mail.gmail.com>
On 6/24/2019 7:42 PM, Paul Moore wrote:
> On Mon, Jun 24, 2019 at 10:15 PM John Johansen
> <john.johansen@canonical.com> wrote:
>> On 6/24/19 6:46 PM, Paul Moore wrote:
>>> On Mon, Jun 24, 2019 at 9:01 PM Casey Schaufler <casey@schaufler-ca.com> wrote:
>>>> On 6/24/2019 2:33 PM, John Johansen wrote:
>>>>> On 6/21/19 11:52 AM, Casey Schaufler wrote:
>>>>>> Change the audit code to store full lsmblob data instead of
>>>>>> a single u32 secid. This allows for multiple security modules
>>>>>> to use the audit system at the same time. It also allows the
>>>>>> removal of scaffolding code that was included during the
>>>>>> revision of LSM interfaces.
>>>>>>
>>>>>> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
>>>>> I know Kees raised this too, but I haven't seen a reply
>>>>>
>>>>> Eric (Paul is already CCed): I have directly added you because of
>>>>> the question below.
>>>>>
>>>>> In summary there isn't necessarily a single secid any more, and
>>>>> we need to know whether dropping the logging of the secid or
>>>>> logging all secids is the correct action.
>>>> It is to be considered that this is an error case. If
>>>> everything is working normally you should have produced
>>>> a secctx previously, which you'll have included in the
>>>> audit record. Including the secid in the record ought to
>>>> be pointless, as the secid is strictly an internal token
>>>> with no meaning outside the running kernel. You are providing
>>>> no security relevant information by providing the secid.
>>>> I will grant the possibility that the secid might be useful
>>>> in debugging, but for that a pr_warn is more appropriate
>>>> than a field in the audit record.
>>> FWIW, this probably should have been CC'd to the audit list.
>>>
>> hrmm indeed, sorry
>>
>>> I agree that this is an error case (security_secid_to_secctx() failed
>>> to resolve the secid) and further that logging the secid, or a
>>> collection of secids, has little value the way things currently work.
>>> Since secids are a private kernel implementation detail, we don't
>>> really display them outside the context of the kernel, including in
>>> the audit logs. Recording a secid in this case doesn't provide
>>> anything meaningful since secids aren't recorded in the audit record
>>> stream, only the secctxs, and there is no "magic decoder ring" to go
>>> between the two in the audit logs, or anywhere else in userspace for
>>> that matter.
>> Okay, thanks. Casey I am good with just a pr_warn here. I just didn't
>> have context of why it was going to the audit_log and didn't want
>> to change that without some more input.
> Hmm. Actually, let me change my comments slightly ... perhaps what we
> should do here is keep the audit_log_format(), but change it from
> audit_log_format("osid=%u",...) to audit_log_format("obj=?"). The "?"
> is used in audit when we can't determine a piece of information, but
> we normally log it. It wasn't used very widely originally, which is
> probably why it isn't in this piece of code.
Works for me. I'll make the change. Thank you.
??
^ permalink raw reply
* Re: [PATCH v6 1/3] mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options
From: Alexander Potapenko @ 2019-06-25 15:42 UTC (permalink / raw)
To: Kees Cook
Cc: Andrew Morton, Christoph Lameter, Masahiro Yamada, Michal Hocko,
James Morris, Serge E. Hallyn, Nick Desaulniers,
Kostya Serebryany, Dmitry Vyukov, Sandeep Patil, Laura Abbott,
Randy Dunlap, Jann Horn, Mark Rutland, Marco Elver,
Linux Memory Management List, linux-security-module,
Kernel Hardening
In-Reply-To: <201906201821.8887E75@keescook>
On Fri, Jun 21, 2019 at 3:37 AM Kees Cook <keescook@chromium.org> wrote:
>
> On Fri, Jun 07, 2019 at 08:42:27AM -0700, Kees Cook wrote:
> > On Thu, Jun 06, 2019 at 06:48:43PM +0200, Alexander Potapenko wrote:
> > > [...]
> > > diff --git a/mm/slub.c b/mm/slub.c
> > > index cd04dbd2b5d0..9c4a8b9a955c 100644
> > > --- a/mm/slub.c
> > > +++ b/mm/slub.c
> > > [...]
> > > @@ -2741,8 +2758,14 @@ static __always_inline void *slab_alloc_node(struct kmem_cache *s,
> > > prefetch_freepointer(s, next_object);
> > > stat(s, ALLOC_FASTPATH);
> > > }
> > > + /*
> > > + * If the object has been wiped upon free, make sure it's fully
> > > + * initialized by zeroing out freelist pointer.
> > > + */
> > > + if (unlikely(slab_want_init_on_free(s)) && object)
> > > + *(void **)object = NULL;
>
> In looking at metadata again, I noticed that I don't think this is
> correct, as it needs to be using s->offset to find the location of the
> freelist pointer:
>
> memset(object + s->offset, 0, sizeof(void *));
In the cases we support s->offset is always zero (we don't initialize
slabs with ctors or RCU), but using its value is a sane
generalization.
> > >
> > > - if (unlikely(gfpflags & __GFP_ZERO) && object)
> > > + if (unlikely(slab_want_init_on_alloc(gfpflags, s)) && object)
> > > memset(object, 0, s->object_size);
>
> init_on_alloc is using "object_size" but init_on_free is using "size". I
> assume the "alloc" wipe is smaller because metadata was just written
> for the allocation?
As noted in another thread, using "size" is incorrect, because it may
overwrite the redzone after the object.
I'll send a patch to fix that.
Overwriting the metadata indeed shouldn't make sense in the allocation case.
> --
> Kees Cook
--
Alexander Potapenko
Software Engineer
Google Germany GmbH
Erika-Mann-Straße, 33
80636 München
Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg
^ permalink raw reply
* Re: [PATCH v4 00/14] ima: introduce IMA Digest Lists extension
From: Mimi Zohar @ 2019-06-25 17:35 UTC (permalink / raw)
To: Roberto Sassu, dmitry.kasatkin, mjg59, Rob Landley
Cc: linux-integrity, linux-security-module, linux-fsdevel, linux-doc,
linux-kernel, silviu.vlasceanu
In-Reply-To: <88d368e6-5b3c-0206-23a0-dc3e0aa385f0@huawei.com>
[Cc'ing Rob Landley]
On Tue, 2019-06-25 at 14:57 +0200, Roberto Sassu wrote:
> Mimi, do you have any thoughts on this version?
I need to look closer, but when I first looked these changes seemed to
be really invasive. Let's first work on getting the CPIO xattr
support upstreamed. Rob Landley said he was going to review and test
them. Do you have any documentation on how to set up a test
environment? I'd really appreciate if others would also help with
reviewing the CPIO patches.
thanks!
Mimi
^ permalink raw reply
* Re: [RFC PATCH v5 1/1] Add dm verity root hash pkcs7 sig validation.
From: Mike Snitzer @ 2019-06-25 18:20 UTC (permalink / raw)
To: Jaskaran Khurana, gmazyland
Cc: linux-security-module, linux-kernel, linux-integrity,
linux-fsdevel, scottsh, ebiggers, jmorris, dm-devel, mpatocka,
agk
In-Reply-To: <20190619191048.20365-2-jaskarankhurana@linux.microsoft.com>
On Wed, Jun 19 2019 at 3:10pm -0400,
Jaskaran Khurana <jaskarankhurana@linux.microsoft.com> wrote:
> The verification is to support cases where the roothash is not secured by
> Trusted Boot, UEFI Secureboot or similar technologies.
> One of the use cases for this is for dm-verity volumes mounted after boot,
> the root hash provided during the creation of the dm-verity volume has to
> be secure and thus in-kernel validation implemented here will be used
> before we trust the root hash and allow the block device to be created.
>
> The signature being provided for verification must verify the root hash and
> must be trusted by the builtin keyring for verification to succeed.
>
> The hash is added as a key of type "user" and the description is passed to
> the kernel so it can look it up and use it for verification.
>
> Kernel commandline parameter will indicate whether to check (only if
> specified) or force (for all dm verity volumes) roothash signature
> verification.
>
> Kernel commandline: dm_verity.verify_sig=1 or 2 for check/force root hash
> signature validation respectively.
>
> Signed-off-by: Jaskaran Khurana <jaskarankhurana@linux.microsoft.com>
Milan and/or others: could you please provide review and if you're OK
with this patch respond accordingly?
Thanks,
Mike
^ permalink raw reply
* Re: [RFC PATCH v4 08/12] security/selinux: Require SGX_MAPWX to map enclave page WX
From: Stephen Smalley @ 2019-06-25 20:19 UTC (permalink / raw)
To: Sean Christopherson, Jarkko Sakkinen
Cc: linux-sgx, linux-security-module, selinux, Bill Roberts,
Casey Schaufler, James Morris, Dave Hansen, Cedric Xing,
Andy Lutomirski, Jethro Beekman, Dr . Greg Wettstein
In-Reply-To: <20190619222401.14942-9-sean.j.christopherson@intel.com>
On 6/19/19 6:23 PM, Sean Christopherson wrote:
> Hook enclave_map() to require a new per-process capability, SGX_MAPWX,
> when mapping an enclave as simultaneously writable and executable.
> Note, @prot contains the actual protection bits that will be set by the
> kernel, not the maximal protection bits specified by userspace when the
> page was first loaded into the enclave.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
> security/selinux/hooks.c | 21 +++++++++++++++++++++
> security/selinux/include/classmap.h | 3 ++-
> 2 files changed, 23 insertions(+), 1 deletion(-)
>
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index 3ec702cf46ca..fc239e541b62 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -6726,6 +6726,23 @@ static void selinux_bpf_prog_free(struct bpf_prog_aux *aux)
> }
> #endif
>
> +#ifdef CONFIG_INTEL_SGX
> +static int selinux_enclave_map(unsigned long prot)
> +{
> + const struct cred *cred = current_cred();
> + u32 sid = cred_sid(cred);
> +
> + /* SGX is supported only in 64-bit kernels. */
> + WARN_ON_ONCE(!default_noexec);
> +
> + if ((prot & PROT_EXEC) && (prot & PROT_WRITE))
> + return avc_has_perm(&selinux_state, sid, sid,
> + SECCLASS_PROCESS2, PROCESS2__SGX_MAPWX,
> + NULL);
Possibly we should use a slightly more general name for the permission
to allow reusing it in the future if/when another architecture
introduces a similar construct under a different branding? ENCLAVE_*
seems slightly more generic than SGX_*.
I was interested in testing this code but sadly the driver reports the
following on my development workstation:
[ 1.644191] sgx: The launch control MSRs are not writable
[ 1.695477] sgx: EPC section 0x70200000-0x75f7ffff
[ 1.771760] sgx: The public key MSRs are not writable
I guess I'm out of luck until/unless I get a NUC or server class
hardware that supports flexible launch control? Seems developer unfriendly.
> + return 0;
> +}
> +#endif
> +
> struct lsm_blob_sizes selinux_blob_sizes __lsm_ro_after_init = {
> .lbs_cred = sizeof(struct task_security_struct),
> .lbs_file = sizeof(struct file_security_struct),
> @@ -6968,6 +6985,10 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
> LSM_HOOK_INIT(bpf_map_free_security, selinux_bpf_map_free),
> LSM_HOOK_INIT(bpf_prog_free_security, selinux_bpf_prog_free),
> #endif
> +
> +#ifdef CONFIG_INTEL_SGX
> + LSM_HOOK_INIT(enclave_map, selinux_enclave_map),
> +#endif
> };
>
> static __init int selinux_init(void)
> diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h
> index 201f7e588a29..cfd91e879bdf 100644
> --- a/security/selinux/include/classmap.h
> +++ b/security/selinux/include/classmap.h
> @@ -51,7 +51,8 @@ struct security_class_mapping secclass_map[] = {
> "execmem", "execstack", "execheap", "setkeycreate",
> "setsockcreate", "getrlimit", NULL } },
> { "process2",
> - { "nnp_transition", "nosuid_transition", NULL } },
> + { "nnp_transition", "nosuid_transition",
> + "sgx_mapwx", NULL } },
> { "system",
> { "ipc_info", "syslog_read", "syslog_mod",
> "syslog_console", "module_request", "module_load", NULL } },
>
^ permalink raw reply
* Re: [RFC PATCH v4 10/12] security/selinux: Add enclave_load() implementation
From: Stephen Smalley @ 2019-06-25 20:34 UTC (permalink / raw)
To: Sean Christopherson, Jarkko Sakkinen
Cc: linux-sgx, linux-security-module, selinux, Bill Roberts,
Casey Schaufler, James Morris, Dave Hansen, Cedric Xing,
Andy Lutomirski, Jethro Beekman, Dr . Greg Wettstein, Paul Moore
In-Reply-To: <20190619222401.14942-11-sean.j.christopherson@intel.com>
On 6/19/19 6:23 PM, Sean Christopherson wrote:
> The goal of selinux_enclave_load() is to provide a facsimile of the
> existing selinux_file_mprotect() and file_map_prot_check() policies,
> but tailored to the unique properties of SGX.
>
> For example, an enclave page is technically backed by a MAP_SHARED file,
> but the "file" is essentially shared memory that is never persisted
> anywhere and also requires execute permissions (for some pages).
>
> Enclaves are also less priveleged than normal user code, e.g. SYSCALL
> instructions #UD if attempted in an enclave. For this reason, add SGX
> specific permissions instead of reusing existing permissions such as
> FILE__EXECUTE so that policies can allow running code in an enclave, or
> allow dynamically loading code in an enclave without having to grant the
> same capability to normal user code outside of the enclave.
>
> Intended use of each permission:
>
> - SGX_EXECDIRTY: dynamically load code within the enclave itself
> - SGX_EXECUNMR: load unmeasured code into the enclave, e.g. Graphene
> - SGX_EXECANON: load code from anonymous memory (likely Graphene)
> - SGX_EXECUTE: load an enclave from a file, i.e. normal behavior
>
> Note, equivalents to FILE__READ and FILE__WRITE are intentionally never
> required. Writes to the enclave page are contained to the EPC, i.e.
> never hit the original file, and read permissions have already been
> vetted (or the VMA doesn't have PROT_READ, in which case loading the
> page into the enclave will fail).
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
> security/selinux/hooks.c | 55 +++++++++++++++++++++++++++--
> security/selinux/include/classmap.h | 5 +--
> 2 files changed, 55 insertions(+), 5 deletions(-)
>
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index fc239e541b62..8a431168e454 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -6727,6 +6727,12 @@ static void selinux_bpf_prog_free(struct bpf_prog_aux *aux)
> #endif
>
> #ifdef CONFIG_INTEL_SGX
> +static inline int sgx_has_perm(u32 sid, u32 requested)
> +{
> + return avc_has_perm(&selinux_state, sid, sid,
> + SECCLASS_PROCESS2, requested, NULL);
> +}
> +
> static int selinux_enclave_map(unsigned long prot)
> {
> const struct cred *cred = current_cred();
> @@ -6736,11 +6742,53 @@ static int selinux_enclave_map(unsigned long prot)
> WARN_ON_ONCE(!default_noexec);
>
> if ((prot & PROT_EXEC) && (prot & PROT_WRITE))
> - return avc_has_perm(&selinux_state, sid, sid,
> - SECCLASS_PROCESS2, PROCESS2__SGX_MAPWX,
> - NULL);
> + return sgx_has_perm(sid, PROCESS2__SGX_MAPWX);
> +
> return 0;
> }
> +
> +static int selinux_enclave_load(struct vm_area_struct *vma, unsigned long prot,
> + bool measured)
> +{
> + const struct cred *cred = current_cred();
> + u32 sid = cred_sid(cred);
> + int ret;
> +
> + /* SGX is supported only in 64-bit kernels. */
> + WARN_ON_ONCE(!default_noexec);
> +
> + /* Only executable enclave pages are restricted in any way. */
> + if (!(prot & PROT_EXEC))
> + return 0;
> +
> + /*
> + * WX at load time only requires EXECDIRTY, e.g. to allow W->X. Actual
> + * WX mappings require MAPWX (see selinux_enclave_map()).
> + */
> + if (prot & PROT_WRITE) {
> + ret = sgx_has_perm(sid, PROCESS2__SGX_EXECDIRTY);
> + if (ret)
> + goto out;
> + }
> + if (!measured) {
> + ret = sgx_has_perm(sid, PROCESS2__SGX_EXECUNMR);
> + if (ret)
> + goto out;
> + }
> +
> + if (!vma->vm_file || IS_PRIVATE(file_inode(vma->vm_file)) ||
> + vma->anon_vma)
> + /*
> + * Loading enclave code from an anonymous mapping or from a
> + * modified private file mapping.
> + */
> + ret = sgx_has_perm(sid, PROCESS2__SGX_EXECANON);
> + else
> + /* Loading from a shared or unmodified private file mapping. */
> + ret = file_has_perm(cred, vma->vm_file, FILE__SGX_EXECUTE);
> +out:
> + return ret;
> +}
Same comment on this patch: we might want to generalize the permission
names in hopes of being able to reuse them in the future for similar
constructs on other architectures. SGX -> ENCLAVE throughout?
> #endif
>
> struct lsm_blob_sizes selinux_blob_sizes __lsm_ro_after_init = {
> @@ -6988,6 +7036,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
>
> #ifdef CONFIG_INTEL_SGX
> LSM_HOOK_INIT(enclave_map, selinux_enclave_map),
> + LSM_HOOK_INIT(enclave_load, selinux_enclave_load),
> #endif
> };
>
> diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h
> index cfd91e879bdf..baa1757be46a 100644
> --- a/security/selinux/include/classmap.h
> +++ b/security/selinux/include/classmap.h
> @@ -7,7 +7,7 @@
>
> #define COMMON_FILE_PERMS COMMON_FILE_SOCK_PERMS, "unlink", "link", \
> "rename", "execute", "quotaon", "mounton", "audit_access", \
> - "open", "execmod"
> + "open", "execmod", "sgx_execute"
>
> #define COMMON_SOCK_PERMS COMMON_FILE_SOCK_PERMS, "bind", "connect", \
> "listen", "accept", "getopt", "setopt", "shutdown", "recvfrom", \
> @@ -52,7 +52,8 @@ struct security_class_mapping secclass_map[] = {
> "setsockcreate", "getrlimit", NULL } },
> { "process2",
> { "nnp_transition", "nosuid_transition",
> - "sgx_mapwx", NULL } },
> + "sgx_mapwx", "sgx_execdirty", "sgx_execanon", "sgx_execunmr",
> + NULL } },
> { "system",
> { "ipc_info", "syslog_read", "syslog_mod",
> "syslog_console", "module_request", "module_load", NULL } },
>
^ permalink raw reply
* Re: [RFC PATCH v4 07/12] LSM: x86/sgx: Introduce ->enclave_map() hook for Intel SGX
From: Stephen Smalley @ 2019-06-25 20:48 UTC (permalink / raw)
To: Xing, Cedric, Christopherson, Sean J, Jarkko Sakkinen
Cc: linux-sgx@vger.kernel.org, linux-security-module@vger.kernel.org,
selinux@vger.kernel.org, Roberts, William C, Schaufler, Casey,
James Morris, Hansen, Dave, Andy Lutomirski, Jethro Beekman,
Dr . Greg Wettstein
In-Reply-To: <960B34DE67B9E140824F1DCDEC400C0F6551847B@ORSMSX116.amr.corp.intel.com>
On 6/21/19 12:54 PM, Xing, Cedric wrote:
>> From: Christopherson, Sean J
>> Sent: Wednesday, June 19, 2019 3:24 PM
>>
>> diff --git a/security/security.c b/security/security.c
>> index 613a5c00e602..03951e08bdfc 100644
>> --- a/security/security.c
>> +++ b/security/security.c
>> @@ -2359,3 +2359,10 @@ void security_bpf_prog_free(struct bpf_prog_aux *aux)
>> call_void_hook(bpf_prog_free_security, aux);
>> }
>> #endif /* CONFIG_BPF_SYSCALL */
>> +
>> +#ifdef CONFIG_INTEL_SGX
>> +int security_enclave_map(unsigned long prot)
>> +{
>> + return call_int_hook(enclave_map, 0, prot);
>> +}
>> +#endif /* CONFIG_INTEL_SGX */
>
> Why is this new security_enclave_map() necessary while security_mmap_file() will also be invoked?
security_mmap_file() doesn't know about enclaves. It will just end up
checking FILE__READ, FILE__WRITE, and FILE__EXECUTE to /dev/sgx/enclave.
This was noted in the patch description.
^ permalink raw reply
* Re: [RFC PATCH v4 09/12] LSM: x86/sgx: Introduce ->enclave_load() hook for Intel SGX
From: Stephen Smalley @ 2019-06-25 21:01 UTC (permalink / raw)
To: Xing, Cedric, Christopherson, Sean J, Jarkko Sakkinen
Cc: linux-sgx@vger.kernel.org, linux-security-module@vger.kernel.org,
selinux@vger.kernel.org, Roberts, William C, Schaufler, Casey,
James Morris, Hansen, Dave, Andy Lutomirski, Jethro Beekman,
Dr . Greg Wettstein
In-Reply-To: <960B34DE67B9E140824F1DCDEC400C0F655184A2@ORSMSX116.amr.corp.intel.com>
On 6/21/19 1:05 PM, Xing, Cedric wrote:
>> From: Christopherson, Sean J
>> Sent: Wednesday, June 19, 2019 3:24 PM
>>
>> diff --git a/include/linux/security.h b/include/linux/security.h
>> index 6a1f54ba6794..572ddfc53039 100644
>> --- a/include/linux/security.h
>> +++ b/include/linux/security.h
>> @@ -1832,11 +1832,18 @@ static inline void security_bpf_prog_free(struct bpf_prog_aux *aux)
>> #ifdef CONFIG_INTEL_SGX
>> #ifdef CONFIG_SECURITY
>> int security_enclave_map(unsigned long prot);
>> +int security_enclave_load(struct vm_area_struct *vma, unsigned long prot,
>> + bool measured);
>> #else
>> static inline int security_enclave_map(unsigned long prot)
>> {
>> return 0;
>> }
>> +static inline int security_enclave_load(struct vm_area_struct *vma,
>> + unsigned long prot, bool measured)
>> +{
>> + return 0;
>> +}
>> #endif /* CONFIG_SECURITY */
>> #endif /* CONFIG_INTEL_SGX */
>
> Parameters to security_enclave_load() are specific on what's being loading only, but unspecific on which enclave to be loaded into. That kills the possibility of an LSM module making enclave dependent decisions.
>
> Btw, if enclave (in the form of struct file) is also passed in as a parameter, it'd let LSM know that file is an enclave, hence would be able to make the same decision in security_mmap_file() as in security_enclave_map(). In other words, you wouldn't need security_enclave_map().
Sorry, you want security_enclave_load() to stash a reference to the
enclave file in some security module-internal state, then match it upon
later security_mmap_file() calls to determine that it is dealing with an
enclave, and then adjust its logic accordingly? When do we release that
reference?
^ permalink raw reply
* Re: [RFC PATCH v4 08/12] security/selinux: Require SGX_MAPWX to map enclave page WX
From: Stephen Smalley @ 2019-06-25 21:05 UTC (permalink / raw)
To: Xing, Cedric, Christopherson, Sean J, Jarkko Sakkinen
Cc: linux-sgx@vger.kernel.org, linux-security-module@vger.kernel.org,
selinux@vger.kernel.org, Roberts, William C, Schaufler, Casey,
James Morris, Hansen, Dave, Andy Lutomirski, Jethro Beekman,
Dr . Greg Wettstein
In-Reply-To: <960B34DE67B9E140824F1DCDEC400C0F655184C3@ORSMSX116.amr.corp.intel.com>
On 6/21/19 1:09 PM, Xing, Cedric wrote:
>> From: Christopherson, Sean J
>> Sent: Wednesday, June 19, 2019 3:24 PM
>>
>> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
>> index 3ec702cf46ca..fc239e541b62 100644
>> --- a/security/selinux/hooks.c
>> +++ b/security/selinux/hooks.c
>> @@ -6726,6 +6726,23 @@ static void selinux_bpf_prog_free(struct bpf_prog_aux *aux)
>> }
>> #endif
>>
>> +#ifdef CONFIG_INTEL_SGX
>> +static int selinux_enclave_map(unsigned long prot)
>> +{
>> + const struct cred *cred = current_cred();
>> + u32 sid = cred_sid(cred);
>> +
>> + /* SGX is supported only in 64-bit kernels. */
>> + WARN_ON_ONCE(!default_noexec);
>> +
>> + if ((prot & PROT_EXEC) && (prot & PROT_WRITE))
>> + return avc_has_perm(&selinux_state, sid, sid,
>> + SECCLASS_PROCESS2, PROCESS2__SGX_MAPWX,
>> + NULL);
>
> Why isn't SGX_MAPWX enclave specific but process wide?
How would you tie it to a specific enclave? What's the object/target
SID? The SID of the enclave inode? Which one? The source vma file,
the /dev/sgx/enclave open instance, the sigstruct file, ...? If a
process can map one enclave WX, what's the benefit of preventing it from
doing likewise for any other enclave it can load?
^ permalink raw reply
* Re: [RFC PATCH v4 10/12] security/selinux: Add enclave_load() implementation
From: Stephen Smalley @ 2019-06-25 21:09 UTC (permalink / raw)
To: Xing, Cedric, Christopherson, Sean J, Jarkko Sakkinen
Cc: linux-sgx@vger.kernel.org, linux-security-module@vger.kernel.org,
selinux@vger.kernel.org, Roberts, William C, Schaufler, Casey,
James Morris, Hansen, Dave, Andy Lutomirski, Jethro Beekman,
Dr . Greg Wettstein
In-Reply-To: <960B34DE67B9E140824F1DCDEC400C0F6551877E@ORSMSX116.amr.corp.intel.com>
On 6/21/19 5:22 PM, Xing, Cedric wrote:
>> From: Christopherson, Sean J
>> Sent: Wednesday, June 19, 2019 3:24 PM
>>
>> Intended use of each permission:
>>
>> - SGX_EXECDIRTY: dynamically load code within the enclave itself
>> - SGX_EXECUNMR: load unmeasured code into the enclave, e.g. Graphene
>
> Why does it matter whether a code page is measured or not?
It won't be incorporated into an attestation?
>
>> - SGX_EXECANON: load code from anonymous memory (likely Graphene)
>
> Graphene doesn't load code from anonymous memory. It loads code dynamically though, as in SGX_EXECDIRTY case.
So do we expect EXECANON to never be triggered at all?
>
>> - SGX_EXECUTE: load an enclave from a file, i.e. normal behavior
>
> Why is SGX_EXECUTE needed from security perspective? Or why isn't FILE__EXECUTE sufficient?
Splitting the SGX permissions from the regular ones allows distinctions
to be made between what can be executed in the host process and what can
be executed in the enclave. The host process may be allowed
FILE__EXECUTE to numerous files that do not contain any code ever
intended to be executed within the enclave.
^ permalink raw reply
* Re: [RFC PATCH v4 09/12] LSM: x86/sgx: Introduce ->enclave_load() hook for Intel SGX
From: Stephen Smalley @ 2019-06-25 21:49 UTC (permalink / raw)
To: Xing, Cedric, Christopherson, Sean J, Jarkko Sakkinen
Cc: linux-sgx@vger.kernel.org, linux-security-module@vger.kernel.org,
selinux@vger.kernel.org, Roberts, William C, Schaufler, Casey,
James Morris, Hansen, Dave, Andy Lutomirski, Jethro Beekman,
Dr . Greg Wettstein
In-Reply-To: <008635cd-9c0b-1367-d250-99aa16b41305@tycho.nsa.gov>
On 6/25/19 5:01 PM, Stephen Smalley wrote:
> On 6/21/19 1:05 PM, Xing, Cedric wrote:
>>> From: Christopherson, Sean J
>>> Sent: Wednesday, June 19, 2019 3:24 PM
>>>
>>> diff --git a/include/linux/security.h b/include/linux/security.h
>>> index 6a1f54ba6794..572ddfc53039 100644
>>> --- a/include/linux/security.h
>>> +++ b/include/linux/security.h
>>> @@ -1832,11 +1832,18 @@ static inline void
>>> security_bpf_prog_free(struct bpf_prog_aux *aux)
>>> #ifdef CONFIG_INTEL_SGX
>>> #ifdef CONFIG_SECURITY
>>> int security_enclave_map(unsigned long prot);
>>> +int security_enclave_load(struct vm_area_struct *vma, unsigned long
>>> prot,
>>> + bool measured);
>>> #else
>>> static inline int security_enclave_map(unsigned long prot)
>>> {
>>> return 0;
>>> }
>>> +static inline int security_enclave_load(struct vm_area_struct *vma,
>>> + unsigned long prot, bool measured)
>>> +{
>>> + return 0;
>>> +}
>>> #endif /* CONFIG_SECURITY */
>>> #endif /* CONFIG_INTEL_SGX */
>>
>> Parameters to security_enclave_load() are specific on what's being
>> loading only, but unspecific on which enclave to be loaded into. That
>> kills the possibility of an LSM module making enclave dependent
>> decisions.
>>
>> Btw, if enclave (in the form of struct file) is also passed in as a
>> parameter, it'd let LSM know that file is an enclave, hence would be
>> able to make the same decision in security_mmap_file() as in
>> security_enclave_map(). In other words, you wouldn't need
>> security_enclave_map().
>
> Sorry, you want security_enclave_load() to stash a reference to the
> enclave file in some security module-internal state, then match it upon
> later security_mmap_file() calls to determine that it is dealing with an
> enclave, and then adjust its logic accordingly? When do we release that
> reference?
I guess you mean set a flag in the enclave file security struct upon
security_enclave_load() and check that flag in security_mmap_file().
This seems somewhat similar to one of Sean's alternatives in the patch
description for 06/12, except by pushing the information from sgx to LSM
upon security_enclave_load() rather than pulling it via a
is_sgx_enclave() helper. Not clear if it is still subject to the same
limitations.
^ permalink raw reply
* [PATCH bpf-next v9 07/10] landlock: Add ptrace restrictions
From: Mickaël Salaün @ 2019-06-25 21:52 UTC (permalink / raw)
To: linux-kernel
Cc: Mickaël Salaün, Aleksa Sarai, Alexander Viro,
Alexei Starovoitov, Andrew Morton, Andy Lutomirski,
Arnaldo Carvalho de Melo, Casey Schaufler, Daniel Borkmann,
David Drysdale, David S . Miller, Eric W . Biederman,
James Morris, Jann Horn, John Johansen, Jonathan Corbet,
Kees Cook, Michael Kerrisk, Mickaël Salaün, Paul Moore,
Sargun Dhillon, Serge E . Hallyn, Shuah Khan, Stephen Smalley,
Tejun Heo, Tetsuo Handa, Thomas Graf, Tycho Andersen, Will Drewry,
kernel-hardening, linux-api, linux-fsdevel, linux-security-module,
netdev
In-Reply-To: <20190625215239.11136-1-mic@digikod.net>
A landlocked process has less privileges than a non-landlocked process
and must then be subject to additional restrictions when manipulating
processes. To be allowed to use ptrace(2) and related syscalls on a
target process, a landlocked process must have a subset of the target
process' rules.
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: James Morris <jmorris@namei.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Serge E. Hallyn <serge@hallyn.com>
---
Changes since v6:
* factor out ptrace check
* constify pointers
* cleanup headers
* use the new security_add_hooks()
---
security/landlock/Makefile | 2 +-
security/landlock/hooks_ptrace.c | 121 +++++++++++++++++++++++++++++++
security/landlock/hooks_ptrace.h | 8 ++
security/landlock/init.c | 2 +
4 files changed, 132 insertions(+), 1 deletion(-)
create mode 100644 security/landlock/hooks_ptrace.c
create mode 100644 security/landlock/hooks_ptrace.h
diff --git a/security/landlock/Makefile b/security/landlock/Makefile
index 270ece5d93de..4500ddb0767e 100644
--- a/security/landlock/Makefile
+++ b/security/landlock/Makefile
@@ -2,4 +2,4 @@ obj-$(CONFIG_SECURITY_LANDLOCK) := landlock.o
landlock-y := init.o \
enforce.o enforce_seccomp.o \
- hooks.o hooks_fs.o
+ hooks.o hooks_fs.o hooks_ptrace.o
diff --git a/security/landlock/hooks_ptrace.c b/security/landlock/hooks_ptrace.c
new file mode 100644
index 000000000000..7f5e8b994e93
--- /dev/null
+++ b/security/landlock/hooks_ptrace.c
@@ -0,0 +1,121 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Landlock LSM - ptrace hooks
+ *
+ * Copyright © 2017 Mickaël Salaün <mic@digikod.net>
+ */
+
+#include <asm/current.h>
+#include <linux/errno.h>
+#include <linux/kernel.h> /* ARRAY_SIZE */
+#include <linux/lsm_hooks.h>
+#include <linux/sched.h> /* struct task_struct */
+#include <linux/seccomp.h>
+
+#include "common.h" /* struct landlock_prog_set */
+#include "hooks.h" /* landlocked() */
+#include "hooks_ptrace.h"
+
+static bool progs_are_subset(const struct landlock_prog_set *parent,
+ const struct landlock_prog_set *child)
+{
+ size_t i;
+
+ if (!parent || !child)
+ return false;
+ if (parent == child)
+ return true;
+
+ for (i = 0; i < ARRAY_SIZE(child->programs); i++) {
+ struct landlock_prog_list *walker;
+ bool found_parent = false;
+
+ if (!parent->programs[i])
+ continue;
+ for (walker = child->programs[i]; walker;
+ walker = walker->prev) {
+ if (walker == parent->programs[i]) {
+ found_parent = true;
+ break;
+ }
+ }
+ if (!found_parent)
+ return false;
+ }
+ return true;
+}
+
+static bool task_has_subset_progs(const struct task_struct *parent,
+ const struct task_struct *child)
+{
+#ifdef CONFIG_SECCOMP_FILTER
+ if (progs_are_subset(parent->seccomp.landlock_prog_set,
+ child->seccomp.landlock_prog_set))
+ /* must be ANDed with other providers (i.e. cgroup) */
+ return true;
+#endif /* CONFIG_SECCOMP_FILTER */
+ return false;
+}
+
+static int task_ptrace(const struct task_struct *parent,
+ const struct task_struct *child)
+{
+ if (!landlocked(parent))
+ return 0;
+
+ if (!landlocked(child))
+ return -EPERM;
+
+ if (task_has_subset_progs(parent, child))
+ return 0;
+
+ return -EPERM;
+}
+
+/**
+ * hook_ptrace_access_check - determine whether the current process may access
+ * another
+ *
+ * @child: the process to be accessed
+ * @mode: the mode of attachment
+ *
+ * If the current task has Landlock programs, then the child must have at least
+ * the same programs. Else denied.
+ *
+ * Determine whether a process may access another, returning 0 if permission
+ * granted, -errno if denied.
+ */
+static int hook_ptrace_access_check(struct task_struct *child,
+ unsigned int mode)
+{
+ return task_ptrace(current, child);
+}
+
+/**
+ * hook_ptrace_traceme - determine whether another process may trace the
+ * current one
+ *
+ * @parent: the task proposed to be the tracer
+ *
+ * If the parent has Landlock programs, then the current task must have the
+ * same or more programs.
+ * Else denied.
+ *
+ * Determine whether the nominated task is permitted to trace the current
+ * process, returning 0 if permission is granted, -errno if denied.
+ */
+static int hook_ptrace_traceme(struct task_struct *parent)
+{
+ return task_ptrace(parent, current);
+}
+
+static struct security_hook_list landlock_hooks[] = {
+ LSM_HOOK_INIT(ptrace_access_check, hook_ptrace_access_check),
+ LSM_HOOK_INIT(ptrace_traceme, hook_ptrace_traceme),
+};
+
+__init void landlock_add_hooks_ptrace(void)
+{
+ security_add_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks),
+ LANDLOCK_NAME);
+}
diff --git a/security/landlock/hooks_ptrace.h b/security/landlock/hooks_ptrace.h
new file mode 100644
index 000000000000..2c2b8a13037f
--- /dev/null
+++ b/security/landlock/hooks_ptrace.h
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Landlock LSM - ptrace hooks
+ *
+ * Copyright © 2017 Mickaël Salaün <mic@digikod.net>
+ */
+
+__init void landlock_add_hooks_ptrace(void);
diff --git a/security/landlock/init.c b/security/landlock/init.c
index 68def2a7af71..d58aa94124b0 100644
--- a/security/landlock/init.c
+++ b/security/landlock/init.c
@@ -13,6 +13,7 @@
#include "common.h" /* LANDLOCK_* */
#include "hooks_fs.h"
+#include "hooks_ptrace.h"
static bool bpf_landlock_is_valid_access(int off, int size,
enum bpf_access_type type, const struct bpf_prog *prog,
@@ -143,6 +144,7 @@ const struct bpf_prog_ops landlock_prog_ops = {};
static int __init landlock_init(void)
{
pr_info(LANDLOCK_NAME ": Initializing (sandbox with seccomp)\n");
+ landlock_add_hooks_ptrace();
landlock_add_hooks_fs();
return 0;
}
--
2.20.1
^ permalink raw reply related
* [PATCH bpf-next v9 01/10] fs,security: Add a new file access type: MAY_CHROOT
From: Mickaël Salaün @ 2019-06-25 21:52 UTC (permalink / raw)
To: linux-kernel
Cc: Mickaël Salaün, Aleksa Sarai, Alexander Viro,
Alexei Starovoitov, Andrew Morton, Andy Lutomirski,
Arnaldo Carvalho de Melo, Casey Schaufler, Daniel Borkmann,
David Drysdale, David S . Miller, Eric W . Biederman,
James Morris, Jann Horn, John Johansen, Jonathan Corbet,
Kees Cook, Michael Kerrisk, Mickaël Salaün, Paul Moore,
Sargun Dhillon, Serge E . Hallyn, Shuah Khan, Stephen Smalley,
Tejun Heo, Tetsuo Handa, Thomas Graf, Tycho Andersen, Will Drewry,
kernel-hardening, linux-api, linux-fsdevel, linux-security-module,
netdev
In-Reply-To: <20190625215239.11136-1-mic@digikod.net>
For compatibility reason, MAY_CHROOT is always set with MAY_CHDIR.
However, this new flag enable to differentiate a chdir form a chroot.
This is needed for the Landlock LSM to be able to evaluate a new root
directory.
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Cc: James Morris <jmorris@namei.org>
Cc: John Johansen <john.johansen@canonical.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Paul Moore <paul@paul-moore.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: linux-fsdevel@vger.kernel.org
---
fs/open.c | 3 ++-
include/linux/fs.h | 1 +
2 files changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/open.c b/fs/open.c
index b5b80469b93d..e8767318fd03 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -494,7 +494,8 @@ int ksys_chroot(const char __user *filename)
if (error)
goto out;
- error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
+ error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR |
+ MAY_CHROOT);
if (error)
goto dput_and_out;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index f7fdfe93e25d..fa6c9d0c152b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -99,6 +99,7 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
#define MAY_CHDIR 0x00000040
/* called from RCU mode, don't block */
#define MAY_NOT_BLOCK 0x00000080
+#define MAY_CHROOT 0x00000100
/*
* flags in file.f_mode. Note that FMODE_READ and FMODE_WRITE must correspond
--
2.20.1
^ permalink raw reply related
* [PATCH bpf-next v9 02/10] bpf: Add eBPF program subtype and is_valid_subtype() verifier
From: Mickaël Salaün @ 2019-06-25 21:52 UTC (permalink / raw)
To: linux-kernel
Cc: Mickaël Salaün, Aleksa Sarai, Alexander Viro,
Alexei Starovoitov, Andrew Morton, Andy Lutomirski,
Arnaldo Carvalho de Melo, Casey Schaufler, Daniel Borkmann,
David Drysdale, David S . Miller, Eric W . Biederman,
James Morris, Jann Horn, John Johansen, Jonathan Corbet,
Kees Cook, Michael Kerrisk, Mickaël Salaün, Paul Moore,
Sargun Dhillon, Serge E . Hallyn, Shuah Khan, Stephen Smalley,
Tejun Heo, Tetsuo Handa, Thomas Graf, Tycho Andersen, Will Drewry,
kernel-hardening, linux-api, linux-fsdevel, linux-security-module,
netdev
In-Reply-To: <20190625215239.11136-1-mic@digikod.net>
The goal of the program subtype is to be able to have different static
fine-grained verifications for a unique program type.
The struct bpf_verifier_ops gets a new optional function:
is_valid_subtype(). This new verifier is called at the beginning of the
eBPF program verification to check if the (optional) program subtype is
valid.
The new helper bpf_load_program_xattr() enables to verify a program with
subtypes.
For now, only Landlock eBPF programs are using a program subtype (see
next commits) but this could be used by other program types in the
future.
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David S. Miller <davem@davemloft.net>
Link: https://lkml.kernel.org/r/20160827205559.GA43880@ast-mbp.thefacebook.com
---
Changes since v8:
* use bpf_load_program_xattr() instead of bpf_load_program() and add
bpf_verify_program_xattr() to deal with subtypes
* remove put_extra() since there is no more "previous" field (for now)
Changes since v7:
* rename LANDLOCK_SUBTYPE_* to LANDLOCK_*
* move subtype in bpf_prog_aux and use only one bit for has_subtype
(suggested by Alexei Starovoitov)
* wrap the prog_subtype with a prog_extra to be able to reference kernel
pointers:
* add an optional put_extra() function to struct bpf_prog_ops to be
able to free the pointed data
* replace all the prog_subtype with prog_extra in the struct
bpf_verifier_ops functions
* remove the ABI field (requested by Alexei Starovoitov)
* rename subtype fields
Changes since v6:
* rename Landlock version to ABI to better reflect its purpose
* fix unsigned integer checks
* fix pointer cast
* constify pointers
* rebase
Changes since v5:
* use a prog_subtype pointer and make it future-proof
* add subtype test
* constify bpf_load_program()'s subtype argument
* cleanup subtype initialization
* rebase
Changes since v4:
* replace the "status" field with "version" (more generic)
* replace the "access" field with "ability" (less confusing)
Changes since v3:
* remove the "origin" field
* add an "option" field
* cleanup comments
---
include/linux/bpf.h | 8 +++++
include/uapi/linux/bpf.h | 9 ++++++
kernel/bpf/core.c | 1 +
kernel/bpf/syscall.c | 32 ++++++++++++++++++-
kernel/bpf/verifier.c | 11 +++++++
net/core/filter.c | 25 ++++++++-------
tools/include/uapi/linux/bpf.h | 9 ++++++
tools/lib/bpf/bpf.c | 10 +++++-
tools/lib/bpf/bpf.h | 2 ++
tools/lib/bpf/libbpf.map | 1 +
tools/testing/selftests/bpf/test_verifier.c | 26 +++++++++++++--
.../testing/selftests/bpf/verifier/subtype.c | 10 ++++++
12 files changed, 128 insertions(+), 16 deletions(-)
create mode 100644 tools/testing/selftests/bpf/verifier/subtype.c
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index a62e7889b0b6..da167d3afecc 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -294,6 +294,11 @@ bpf_ctx_record_field_size(struct bpf_insn_access_aux *aux, u32 size)
aux->ctx_field_size = size;
}
+/* specific data per program type */
+struct bpf_prog_extra {
+ union bpf_prog_subtype subtype;
+};
+
struct bpf_prog_ops {
int (*test_run)(struct bpf_prog *prog, const union bpf_attr *kattr,
union bpf_attr __user *uattr);
@@ -319,6 +324,8 @@ struct bpf_verifier_ops {
const struct bpf_insn *src,
struct bpf_insn *dst,
struct bpf_prog *prog, u32 *target_size);
+ // TODO?: convert to bool (*is_valid_subtype)(struct bpf_prog *prog);
+ bool (*is_valid_subtype)(struct bpf_prog_extra *prog_extra);
};
struct bpf_prog_offload_ops {
@@ -418,6 +425,7 @@ struct bpf_prog_aux {
struct work_struct work;
struct rcu_head rcu;
};
+ struct bpf_prog_extra *extra;
};
struct bpf_array {
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index b077507efa3f..ddae50373d58 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -355,6 +355,13 @@ struct bpf_stack_build_id {
};
};
+union bpf_prog_subtype {
+ struct {
+ __u32 type; /* enum landlock_hook_type */
+ __aligned_u64 triggers; /* LANDLOCK_TRIGGER_* */
+ } landlock_hook;
+} __attribute__((aligned(8)));
+
union bpf_attr {
struct { /* anonymous struct used by BPF_MAP_CREATE command */
__u32 map_type; /* one of enum bpf_map_type */
@@ -409,6 +416,8 @@ union bpf_attr {
__u32 line_info_rec_size; /* userspace bpf_line_info size */
__aligned_u64 line_info; /* line info */
__u32 line_info_cnt; /* number of bpf_line_info records */
+ __aligned_u64 prog_subtype; /* bpf_prog_subtype address */
+ __u32 prog_subtype_size;
};
struct { /* anonymous struct used by BPF_OBJ_* commands */
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index ad3be85f1411..8ad392e52328 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -255,6 +255,7 @@ void __bpf_prog_free(struct bpf_prog *fp)
{
if (fp->aux) {
free_percpu(fp->aux->stats);
+ kfree(fp->aux->extra);
kfree(fp->aux);
}
vfree(fp);
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 7713cf39795a..7dd3376904d4 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1596,7 +1596,7 @@ bpf_prog_load_check_attach_type(enum bpf_prog_type prog_type,
}
/* last field in 'union bpf_attr' used by this command */
-#define BPF_PROG_LOAD_LAST_FIELD line_info_cnt
+#define BPF_PROG_LOAD_LAST_FIELD prog_subtype_size
static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr)
{
@@ -1686,6 +1686,36 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr)
if (err)
goto free_prog;
+ /* copy eBPF program subtype from user space */
+ if (attr->prog_subtype) {
+ u32 size;
+
+ err = bpf_check_uarg_tail_zero(
+ u64_to_user_ptr(attr->prog_subtype),
+ sizeof(prog->aux->extra->subtype),
+ attr->prog_subtype_size);
+ if (err)
+ goto free_prog;
+ size = min_t(u32, attr->prog_subtype_size,
+ sizeof(prog->aux->extra->subtype));
+
+ prog->aux->extra = kzalloc(sizeof(*prog->aux->extra),
+ GFP_KERNEL | GFP_USER);
+ if (!prog->aux->extra) {
+ err = -ENOMEM;
+ goto free_prog;
+ }
+ if (copy_from_user(&prog->aux->extra->subtype,
+ u64_to_user_ptr(attr->prog_subtype), size)
+ != 0) {
+ err = -EFAULT;
+ goto free_prog;
+ }
+ } else if (attr->prog_subtype_size != 0) {
+ err = -EINVAL;
+ goto free_prog;
+ }
+
/* run eBPF verifier */
err = bpf_check(&prog, attr, uattr);
if (err < 0)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 0e079b2298f8..930260683d0a 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -9167,6 +9167,17 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr,
if (ret < 0)
goto skip_full_check;
+ if (env->ops->is_valid_subtype) {
+ if (!env->ops->is_valid_subtype(env->prog->aux->extra)) {
+ ret = -EINVAL;
+ goto err_unlock;
+ }
+ } else if (env->prog->aux->extra) {
+ /* do not accept a subtype if the program does not handle it */
+ ret = -EINVAL;
+ goto err_unlock;
+ }
+
if (bpf_prog_is_dev_bound(env->prog->aux)) {
ret = bpf_prog_offload_verifier_prep(env->prog);
if (ret)
diff --git a/net/core/filter.c b/net/core/filter.c
index 2014d76e0d2a..0160237e5cd8 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5846,7 +5846,8 @@ bool bpf_helper_changes_pkt_data(void *func)
}
static const struct bpf_func_proto *
-bpf_base_func_proto(enum bpf_func_id func_id)
+bpf_base_func_proto(enum bpf_func_id func_id,
+ const struct bpf_prog_extra *prog_extra)
{
switch (func_id) {
case BPF_FUNC_map_lookup_elem:
@@ -5902,7 +5903,7 @@ sock_filter_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
case BPF_FUNC_get_local_storage:
return &bpf_get_local_storage_proto;
default:
- return bpf_base_func_proto(func_id);
+ return bpf_base_func_proto(func_id, prog->aux->extra);
}
}
@@ -5942,7 +5943,7 @@ sock_addr_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
case BPF_FUNC_sk_storage_delete:
return &bpf_sk_storage_delete_proto;
default:
- return bpf_base_func_proto(func_id);
+ return bpf_base_func_proto(func_id, prog->aux->extra);
}
}
@@ -5959,7 +5960,7 @@ sk_filter_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
case BPF_FUNC_get_socket_uid:
return &bpf_get_socket_uid_proto;
default:
- return bpf_base_func_proto(func_id);
+ return bpf_base_func_proto(func_id, prog->aux->extra);
}
}
@@ -6096,7 +6097,7 @@ tc_cls_act_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_skb_ecn_set_ce_proto;
#endif
default:
- return bpf_base_func_proto(func_id);
+ return bpf_base_func_proto(func_id, prog->aux->extra);
}
}
@@ -6135,7 +6136,7 @@ xdp_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_tcp_check_syncookie_proto;
#endif
default:
- return bpf_base_func_proto(func_id);
+ return bpf_base_func_proto(func_id, prog->aux->extra);
}
}
@@ -6171,7 +6172,7 @@ sock_ops_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_tcp_sock_proto;
#endif /* CONFIG_INET */
default:
- return bpf_base_func_proto(func_id);
+ return bpf_base_func_proto(func_id, prog->aux->extra);
}
}
@@ -6197,7 +6198,7 @@ sk_msg_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
case BPF_FUNC_msg_pop_data:
return &bpf_msg_pop_data_proto;
default:
- return bpf_base_func_proto(func_id);
+ return bpf_base_func_proto(func_id, prog->aux->extra);
}
}
@@ -6237,7 +6238,7 @@ sk_skb_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_skc_lookup_tcp_proto;
#endif
default:
- return bpf_base_func_proto(func_id);
+ return bpf_base_func_proto(func_id, prog->aux->extra);
}
}
@@ -6248,7 +6249,7 @@ flow_dissector_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
case BPF_FUNC_skb_load_bytes:
return &bpf_flow_dissector_load_bytes_proto;
default:
- return bpf_base_func_proto(func_id);
+ return bpf_base_func_proto(func_id, prog->aux->extra);
}
}
@@ -6275,7 +6276,7 @@ lwt_out_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
case BPF_FUNC_skb_under_cgroup:
return &bpf_skb_under_cgroup_proto;
default:
- return bpf_base_func_proto(func_id);
+ return bpf_base_func_proto(func_id, prog->aux->extra);
}
}
@@ -8611,7 +8612,7 @@ sk_reuseport_func_proto(enum bpf_func_id func_id,
case BPF_FUNC_skb_load_bytes_relative:
return &sk_reuseport_load_bytes_relative_proto;
default:
- return bpf_base_func_proto(func_id);
+ return bpf_base_func_proto(func_id, prog->aux->extra);
}
}
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index b077507efa3f..ddae50373d58 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -355,6 +355,13 @@ struct bpf_stack_build_id {
};
};
+union bpf_prog_subtype {
+ struct {
+ __u32 type; /* enum landlock_hook_type */
+ __aligned_u64 triggers; /* LANDLOCK_TRIGGER_* */
+ } landlock_hook;
+} __attribute__((aligned(8)));
+
union bpf_attr {
struct { /* anonymous struct used by BPF_MAP_CREATE command */
__u32 map_type; /* one of enum bpf_map_type */
@@ -409,6 +416,8 @@ union bpf_attr {
__u32 line_info_rec_size; /* userspace bpf_line_info size */
__aligned_u64 line_info; /* line info */
__u32 line_info_cnt; /* number of bpf_line_info records */
+ __aligned_u64 prog_subtype; /* bpf_prog_subtype address */
+ __u32 prog_subtype_size;
};
struct { /* anonymous struct used by BPF_OBJ_* commands */
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index c7d7993c44bb..ecd894344bbd 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -227,6 +227,9 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
memset(&attr, 0, sizeof(attr));
attr.prog_type = load_attr->prog_type;
+ attr.prog_subtype = ptr_to_u64(load_attr->prog_subtype);
+ attr.prog_subtype_size = load_attr->prog_subtype ?
+ sizeof(*load_attr->prog_subtype) : 0;
attr.expected_attach_type = load_attr->expected_attach_type;
attr.insn_cnt = (__u32)load_attr->insns_cnt;
attr.insns = ptr_to_u64(load_attr->insns);
@@ -332,6 +335,11 @@ int bpf_load_program(enum bpf_prog_type type, const struct bpf_insn *insns,
return bpf_load_program_xattr(&load_attr, log_buf, log_buf_sz);
}
+int bpf_verify_program_xattr(union bpf_attr *attr, size_t attr_sz)
+{
+ return sys_bpf_prog_load(attr, attr_sz);
+}
+
int bpf_verify_program(enum bpf_prog_type type, const struct bpf_insn *insns,
size_t insns_cnt, __u32 prog_flags, const char *license,
__u32 kern_version, char *log_buf, size_t log_buf_sz,
@@ -351,7 +359,7 @@ int bpf_verify_program(enum bpf_prog_type type, const struct bpf_insn *insns,
attr.kern_version = kern_version;
attr.prog_flags = prog_flags;
- return sys_bpf_prog_load(&attr, sizeof(attr));
+ return bpf_verify_program_xattr(&attr, sizeof(attr));
}
int bpf_map_update_elem(int fd, const void *key, const void *value,
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index ff42ca043dc8..7cd600d49f9e 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -88,6 +88,7 @@ struct bpf_load_program_attr {
__u32 line_info_cnt;
__u32 log_level;
__u32 prog_flags;
+ const union bpf_prog_subtype *prog_subtype;
};
/* Flags to direct loading requirements */
@@ -102,6 +103,7 @@ LIBBPF_API int bpf_load_program(enum bpf_prog_type type,
const struct bpf_insn *insns, size_t insns_cnt,
const char *license, __u32 kern_version,
char *log_buf, size_t log_buf_sz);
+LIBBPF_API int bpf_verify_program_xattr(union bpf_attr *attr, size_t attr_sz);
LIBBPF_API int bpf_verify_program(enum bpf_prog_type type,
const struct bpf_insn *insns,
size_t insns_cnt, __u32 prog_flags,
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 2c6d835620d2..48c9269a0496 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -107,6 +107,7 @@ LIBBPF_0.0.1 {
bpf_set_link_xdp_fd;
bpf_task_fd_query;
bpf_verify_program;
+ bpf_verify_program_xattr;
btf__fd;
btf__find_by_name;
btf__free;
diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index c5514daf8865..93faffd31fc3 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -105,6 +105,8 @@ struct bpf_test {
__u64 data64[TEST_DATA_LEN / 8];
};
} retvals[MAX_TEST_RUNS];
+ bool has_prog_subtype;
+ union bpf_prog_subtype prog_subtype;
};
/* Note we want this to be 64 bit aligned so that the end of our array is
@@ -122,6 +124,11 @@ struct other_val {
long long bar;
};
+static inline __u64 ptr_to_u64(const void *ptr)
+{
+ return (__u64) (unsigned long) ptr;
+}
+
static void bpf_fill_ld_abs_vlan_push_pop(struct bpf_test *self)
{
/* test: {skb->data[0], vlan_push} x 51 + {skb->data[0], vlan_pop} x 51 */
@@ -856,6 +863,9 @@ static void do_test_single(struct bpf_test *test, bool unpriv,
int fixup_skips;
__u32 pflags;
int i, err;
+ union bpf_attr attr;
+ union bpf_prog_subtype *prog_subtype =
+ test->has_prog_subtype ? &test->prog_subtype : NULL;
for (i = 0; i < MAX_NR_MAPS; i++)
map_fds[i] = -1;
@@ -881,8 +891,20 @@ static void do_test_single(struct bpf_test *test, bool unpriv,
pflags |= BPF_F_STRICT_ALIGNMENT;
if (test->flags & F_NEEDS_EFFICIENT_UNALIGNED_ACCESS)
pflags |= BPF_F_ANY_ALIGNMENT;
- fd_prog = bpf_verify_program(prog_type, prog, prog_len, pflags,
- "GPL", 0, bpf_vlog, sizeof(bpf_vlog), 4);
+
+ memset(&attr, 0, sizeof(attr));
+ attr.prog_type = prog_type;
+ attr.prog_subtype = ptr_to_u64(prog_subtype);
+ attr.prog_subtype_size = prog_subtype ? sizeof(*prog_subtype) : 0;
+ attr.insn_cnt = (__u32)prog_len;
+ attr.insns = ptr_to_u64(prog);
+ attr.license = ptr_to_u64("GPL");
+ bpf_vlog[0] = 0;
+ attr.log_buf = ptr_to_u64(bpf_vlog);
+ attr.log_size = sizeof(bpf_vlog);
+ attr.log_level = 4;
+ attr.prog_flags = pflags;
+ fd_prog = bpf_verify_program_xattr(&attr, sizeof(attr));
if (fd_prog < 0 && !bpf_probe_prog_type(prog_type, 0)) {
printf("SKIP (unsupported program type %d)\n", prog_type);
skips++;
diff --git a/tools/testing/selftests/bpf/verifier/subtype.c b/tools/testing/selftests/bpf/verifier/subtype.c
new file mode 100644
index 000000000000..cf614223d53f
--- /dev/null
+++ b/tools/testing/selftests/bpf/verifier/subtype.c
@@ -0,0 +1,10 @@
+{
+ "superfluous subtype",
+ .insns = {
+ BPF_MOV32_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .errstr = "",
+ .result = REJECT,
+ .has_prog_subtype = true,
+},
--
2.20.1
^ permalink raw reply related
* [PATCH bpf-next v9 03/10] bpf,landlock: Define an eBPF program type for Landlock hooks
From: Mickaël Salaün @ 2019-06-25 21:52 UTC (permalink / raw)
To: linux-kernel
Cc: Mickaël Salaün, Aleksa Sarai, Alexander Viro,
Alexei Starovoitov, Andrew Morton, Andy Lutomirski,
Arnaldo Carvalho de Melo, Casey Schaufler, Daniel Borkmann,
David Drysdale, David S . Miller, Eric W . Biederman,
James Morris, Jann Horn, John Johansen, Jonathan Corbet,
Kees Cook, Michael Kerrisk, Mickaël Salaün, Paul Moore,
Sargun Dhillon, Serge E . Hallyn, Shuah Khan, Stephen Smalley,
Tejun Heo, Tetsuo Handa, Thomas Graf, Tycho Andersen, Will Drewry,
kernel-hardening, linux-api, linux-fsdevel, linux-security-module,
netdev
In-Reply-To: <20190625215239.11136-1-mic@digikod.net>
Add a new type of eBPF program used by Landlock hooks. This type of
program can be chained with the same eBPF program type (according to
subtype rules). A state can be kept with a value available in the
program's context (e.g. named "cookie" for Landlock programs).
This new BPF program type will be registered with the Landlock LSM
initialization.
Add an initial Landlock Kconfig and update the MAINTAINERS file.
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: James Morris <jmorris@namei.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Serge E. Hallyn <serge@hallyn.com>
---
Changes since v8:
* Remove the chaining concept from the eBPF program contexts (chain and
cookie). We need to keep these subtypes this way to be able to make
them evolve, though.
* remove bpf_landlock_put_extra() because there is no more a "previous"
field to free (for now)
Changes since v7:
* cosmetic fixes
* rename LANDLOCK_SUBTYPE_* to LANDLOCK_*
* cleanup UAPI definitions and move them from bpf.h to landlock.h
(suggested by Alexei Starovoitov)
* disable Landlock by default (suggested by Alexei Starovoitov)
* rename BPF_PROG_TYPE_LANDLOCK_{RULE,HOOK}
* update the Kconfig
* update the MAINTAINERS file
* replace the IOCTL, LOCK and FCNTL events with FS_PICK, FS_WALK and
FS_GET hook types
* add the ability to chain programs with an eBPF program file descriptor
(i.e. the "previous" field in a Landlock subtype) and keep a state
with a "cookie" value available from the context
* add a "triggers" subtype bitfield to match specific actions (e.g.
append, chdir, read...)
Changes since v6:
* add 3 more sub-events: IOCTL, LOCK, FCNTL
https://lkml.kernel.org/r/2fbc99a6-f190-f335-bd14-04bdeed35571@digikod.net
* rename LANDLOCK_VERSION to LANDLOCK_ABI to better reflect its purpose,
and move it from landlock.h to common.h
* rename BPF_PROG_TYPE_LANDLOCK to BPF_PROG_TYPE_LANDLOCK_RULE: an eBPF
program could be used for something else than a rule
* simplify struct landlock_context by removing the arch and syscall_nr fields
* remove all eBPF map functions call, remove ABILITY_WRITE
* refactor bpf_landlock_func_proto() (suggested by Kees Cook)
* constify pointers
* fix doc inclusion
Changes since v5:
* rename file hooks.c to init.c
* fix spelling
Changes since v4:
* merge a minimal (not enabled) LSM code and Kconfig in this commit
Changes since v3:
* split commit
* revamp the landlock_context:
* add arch, syscall_nr and syscall_cmd (ioctl, fcntl…) to be able to
cross-check action with the event type
* replace args array with dedicated fields to ease the addition of new
fields
---
MAINTAINERS | 13 ++++
include/linux/bpf_types.h | 3 +
include/uapi/linux/bpf.h | 1 +
include/uapi/linux/landlock.h | 109 +++++++++++++++++++++++++++
security/Kconfig | 1 +
security/Makefile | 2 +
security/landlock/Kconfig | 18 +++++
security/landlock/Makefile | 3 +
security/landlock/common.h | 26 +++++++
security/landlock/init.c | 110 ++++++++++++++++++++++++++++
tools/include/uapi/linux/bpf.h | 1 +
tools/include/uapi/linux/landlock.h | 109 +++++++++++++++++++++++++++
tools/lib/bpf/libbpf.c | 1 +
tools/lib/bpf/libbpf_probes.c | 1 +
14 files changed, 398 insertions(+)
create mode 100644 include/uapi/linux/landlock.h
create mode 100644 security/landlock/Kconfig
create mode 100644 security/landlock/Makefile
create mode 100644 security/landlock/common.h
create mode 100644 security/landlock/init.c
create mode 100644 tools/include/uapi/linux/landlock.h
diff --git a/MAINTAINERS b/MAINTAINERS
index 606d1f80bc49..4a5edc14ee84 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8807,6 +8807,19 @@ F: net/core/skmsg.c
F: net/core/sock_map.c
F: net/ipv4/tcp_bpf.c
+LANDLOCK SECURITY MODULE
+M: Mickaël Salaün <mic@digikod.net>
+S: Supported
+F: Documentation/security/landlock/
+F: include/linux/landlock.h
+F: include/uapi/linux/landlock.h
+F: samples/bpf/landlock*
+F: security/landlock/
+F: tools/include/uapi/linux/landlock.h
+F: tools/testing/selftests/landlock/
+K: landlock
+K: LANDLOCK
+
LANTIQ / INTEL Ethernet drivers
M: Hauke Mehrtens <hauke@hauke-m.de>
L: netdev@vger.kernel.org
diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h
index 5a9975678d6f..dee8b82e31b1 100644
--- a/include/linux/bpf_types.h
+++ b/include/linux/bpf_types.h
@@ -37,6 +37,9 @@ BPF_PROG_TYPE(BPF_PROG_TYPE_LIRC_MODE2, lirc_mode2)
#ifdef CONFIG_INET
BPF_PROG_TYPE(BPF_PROG_TYPE_SK_REUSEPORT, sk_reuseport)
#endif
+#ifdef CONFIG_SECURITY_LANDLOCK
+BPF_PROG_TYPE(BPF_PROG_TYPE_LANDLOCK_HOOK, landlock)
+#endif
BPF_MAP_TYPE(BPF_MAP_TYPE_ARRAY, array_map_ops)
BPF_MAP_TYPE(BPF_MAP_TYPE_PERCPU_ARRAY, percpu_array_map_ops)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index ddae50373d58..50145d448bc3 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -170,6 +170,7 @@ enum bpf_prog_type {
BPF_PROG_TYPE_FLOW_DISSECTOR,
BPF_PROG_TYPE_CGROUP_SYSCTL,
BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE,
+ BPF_PROG_TYPE_LANDLOCK_HOOK,
};
enum bpf_attach_type {
diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h
new file mode 100644
index 000000000000..9e6d8e10ec2c
--- /dev/null
+++ b/include/uapi/linux/landlock.h
@@ -0,0 +1,109 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Landlock - UAPI headers
+ *
+ * Copyright © 2017-2019 Mickaël Salaün <mic@digikod.net>
+ * Copyright © 2018-2019 ANSSI
+ */
+
+#ifndef _UAPI__LINUX_LANDLOCK_H__
+#define _UAPI__LINUX_LANDLOCK_H__
+
+#include <linux/types.h>
+
+#define LANDLOCK_RET_ALLOW 0
+#define LANDLOCK_RET_DENY 1
+
+/**
+ * enum landlock_hook_type - hook type for which a Landlock program is called
+ *
+ * A hook is a policy decision point which exposes the same context type for
+ * each program evaluation.
+ *
+ * @LANDLOCK_HOOK_FS_PICK: called for the last element of a file path
+ * @LANDLOCK_HOOK_FS_WALK: called for each directory of a file path (excluding
+ * the directory passed to fs_pick, if any)
+ */
+enum landlock_hook_type {
+ LANDLOCK_HOOK_FS_PICK = 1,
+ LANDLOCK_HOOK_FS_WALK,
+};
+
+/**
+ * DOC: landlock_triggers
+ *
+ * A landlock trigger is used as a bitmask in subtype.landlock_hook.triggers
+ * for a fs_pick program. It defines a set of actions for which the program
+ * should verify an access request.
+ *
+ * - %LANDLOCK_TRIGGER_FS_PICK_APPEND
+ * - %LANDLOCK_TRIGGER_FS_PICK_CHDIR
+ * - %LANDLOCK_TRIGGER_FS_PICK_CHROOT
+ * - %LANDLOCK_TRIGGER_FS_PICK_CREATE
+ * - %LANDLOCK_TRIGGER_FS_PICK_EXECUTE
+ * - %LANDLOCK_TRIGGER_FS_PICK_FCNTL
+ * - %LANDLOCK_TRIGGER_FS_PICK_GETATTR
+ * - %LANDLOCK_TRIGGER_FS_PICK_IOCTL
+ * - %LANDLOCK_TRIGGER_FS_PICK_LINK
+ * - %LANDLOCK_TRIGGER_FS_PICK_LINKTO
+ * - %LANDLOCK_TRIGGER_FS_PICK_LOCK
+ * - %LANDLOCK_TRIGGER_FS_PICK_MAP
+ * - %LANDLOCK_TRIGGER_FS_PICK_MOUNTON
+ * - %LANDLOCK_TRIGGER_FS_PICK_OPEN
+ * - %LANDLOCK_TRIGGER_FS_PICK_READ
+ * - %LANDLOCK_TRIGGER_FS_PICK_READDIR
+ * - %LANDLOCK_TRIGGER_FS_PICK_RECEIVE
+ * - %LANDLOCK_TRIGGER_FS_PICK_RENAME
+ * - %LANDLOCK_TRIGGER_FS_PICK_RENAMETO
+ * - %LANDLOCK_TRIGGER_FS_PICK_RMDIR
+ * - %LANDLOCK_TRIGGER_FS_PICK_SETATTR
+ * - %LANDLOCK_TRIGGER_FS_PICK_TRANSFER
+ * - %LANDLOCK_TRIGGER_FS_PICK_UNLINK
+ * - %LANDLOCK_TRIGGER_FS_PICK_WRITE
+ */
+#define LANDLOCK_TRIGGER_FS_PICK_APPEND (1ULL << 0)
+#define LANDLOCK_TRIGGER_FS_PICK_CHDIR (1ULL << 1)
+#define LANDLOCK_TRIGGER_FS_PICK_CHROOT (1ULL << 2)
+#define LANDLOCK_TRIGGER_FS_PICK_CREATE (1ULL << 3)
+#define LANDLOCK_TRIGGER_FS_PICK_EXECUTE (1ULL << 4)
+#define LANDLOCK_TRIGGER_FS_PICK_FCNTL (1ULL << 5)
+#define LANDLOCK_TRIGGER_FS_PICK_GETATTR (1ULL << 6)
+#define LANDLOCK_TRIGGER_FS_PICK_IOCTL (1ULL << 7)
+#define LANDLOCK_TRIGGER_FS_PICK_LINK (1ULL << 8)
+#define LANDLOCK_TRIGGER_FS_PICK_LINKTO (1ULL << 9)
+#define LANDLOCK_TRIGGER_FS_PICK_LOCK (1ULL << 10)
+#define LANDLOCK_TRIGGER_FS_PICK_MAP (1ULL << 11)
+#define LANDLOCK_TRIGGER_FS_PICK_MOUNTON (1ULL << 12)
+#define LANDLOCK_TRIGGER_FS_PICK_OPEN (1ULL << 13)
+#define LANDLOCK_TRIGGER_FS_PICK_READ (1ULL << 14)
+#define LANDLOCK_TRIGGER_FS_PICK_READDIR (1ULL << 15)
+#define LANDLOCK_TRIGGER_FS_PICK_RECEIVE (1ULL << 16)
+#define LANDLOCK_TRIGGER_FS_PICK_RENAME (1ULL << 17)
+#define LANDLOCK_TRIGGER_FS_PICK_RENAMETO (1ULL << 18)
+#define LANDLOCK_TRIGGER_FS_PICK_RMDIR (1ULL << 19)
+#define LANDLOCK_TRIGGER_FS_PICK_SETATTR (1ULL << 20)
+#define LANDLOCK_TRIGGER_FS_PICK_TRANSFER (1ULL << 21)
+#define LANDLOCK_TRIGGER_FS_PICK_UNLINK (1ULL << 22)
+#define LANDLOCK_TRIGGER_FS_PICK_WRITE (1ULL << 23)
+
+/**
+ * struct landlock_ctx_fs_pick - context accessible to a fs_pick program
+ *
+ * @inode: pointer to the current kernel object that can be used to compare
+ * inodes from an inode map.
+ */
+struct landlock_ctx_fs_pick {
+ __u64 inode;
+};
+
+/**
+ * struct landlock_ctx_fs_walk - context accessible to a fs_walk program
+ *
+ * @inode: pointer to the current kernel object that can be used to compare
+ * inodes from an inode map.
+ */
+struct landlock_ctx_fs_walk {
+ __u64 inode;
+};
+
+#endif /* _UAPI__LINUX_LANDLOCK_H__ */
diff --git a/security/Kconfig b/security/Kconfig
index 466cc1f8ffed..d3c070a01470 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -237,6 +237,7 @@ source "security/apparmor/Kconfig"
source "security/loadpin/Kconfig"
source "security/yama/Kconfig"
source "security/safesetid/Kconfig"
+source "security/landlock/Kconfig"
source "security/integrity/Kconfig"
diff --git a/security/Makefile b/security/Makefile
index c598b904938f..396ff107f70d 100644
--- a/security/Makefile
+++ b/security/Makefile
@@ -11,6 +11,7 @@ subdir-$(CONFIG_SECURITY_APPARMOR) += apparmor
subdir-$(CONFIG_SECURITY_YAMA) += yama
subdir-$(CONFIG_SECURITY_LOADPIN) += loadpin
subdir-$(CONFIG_SECURITY_SAFESETID) += safesetid
+subdir-$(CONFIG_SECURITY_LANDLOCK) += landlock
# always enable default capabilities
obj-y += commoncap.o
@@ -27,6 +28,7 @@ obj-$(CONFIG_SECURITY_APPARMOR) += apparmor/
obj-$(CONFIG_SECURITY_YAMA) += yama/
obj-$(CONFIG_SECURITY_LOADPIN) += loadpin/
obj-$(CONFIG_SECURITY_SAFESETID) += safesetid/
+obj-$(CONFIG_SECURITY_LANDLOCK) += landlock/
obj-$(CONFIG_CGROUP_DEVICE) += device_cgroup.o
# Object integrity file lists
diff --git a/security/landlock/Kconfig b/security/landlock/Kconfig
new file mode 100644
index 000000000000..8bd103102008
--- /dev/null
+++ b/security/landlock/Kconfig
@@ -0,0 +1,18 @@
+config SECURITY_LANDLOCK
+ bool "Landlock support"
+ depends on SECURITY
+ depends on BPF_SYSCALL
+ depends on SECCOMP_FILTER
+ default n
+ help
+ This selects Landlock, a programmatic access control. It enables to
+ restrict processes on the fly (i.e. create a sandbox). The security
+ policy is a set of eBPF programs, dedicated to deny a list of actions
+ on specific kernel objects (e.g. file).
+
+ You need to enable seccomp filter to apply a security policy to a
+ process hierarchy (e.g. application with built-in sandboxing).
+
+ See Documentation/security/landlock/ for further information.
+
+ If you are unsure how to answer this question, answer N.
diff --git a/security/landlock/Makefile b/security/landlock/Makefile
new file mode 100644
index 000000000000..7205f9a7a2ee
--- /dev/null
+++ b/security/landlock/Makefile
@@ -0,0 +1,3 @@
+obj-$(CONFIG_SECURITY_LANDLOCK) := landlock.o
+
+landlock-y := init.o
diff --git a/security/landlock/common.h b/security/landlock/common.h
new file mode 100644
index 000000000000..fd63ed1592a7
--- /dev/null
+++ b/security/landlock/common.h
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Landlock LSM - private headers
+ *
+ * Copyright © 2016-2019 Mickaël Salaün <mic@digikod.net>
+ * Copyright © 2018-2019 ANSSI
+ */
+
+#ifndef _SECURITY_LANDLOCK_COMMON_H
+#define _SECURITY_LANDLOCK_COMMON_H
+
+#include <linux/bpf.h> /* enum bpf_prog_aux */
+#include <linux/filter.h> /* bpf_prog */
+#include <linux/refcount.h> /* refcount_t */
+#include <uapi/linux/landlock.h> /* enum landlock_hook_type */
+
+#define LANDLOCK_NAME "landlock"
+
+/* UAPI bounds and bitmasks */
+
+#define _LANDLOCK_HOOK_LAST LANDLOCK_HOOK_FS_WALK
+
+#define _LANDLOCK_TRIGGER_FS_PICK_LAST LANDLOCK_TRIGGER_FS_PICK_WRITE
+#define _LANDLOCK_TRIGGER_FS_PICK_MASK ((_LANDLOCK_TRIGGER_FS_PICK_LAST << 1ULL) - 1)
+
+#endif /* _SECURITY_LANDLOCK_COMMON_H */
diff --git a/security/landlock/init.c b/security/landlock/init.c
new file mode 100644
index 000000000000..03073cd0fc4e
--- /dev/null
+++ b/security/landlock/init.c
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Landlock LSM - init
+ *
+ * Copyright © 2016-2019 Mickaël Salaün <mic@digikod.net>
+ * Copyright © 2018-2019 ANSSI
+ */
+
+#include <linux/bpf.h> /* enum bpf_access_type */
+#include <linux/capability.h> /* capable */
+#include <linux/filter.h> /* struct bpf_prog */
+
+#include "common.h" /* LANDLOCK_* */
+
+static bool bpf_landlock_is_valid_access(int off, int size,
+ enum bpf_access_type type, const struct bpf_prog *prog,
+ struct bpf_insn_access_aux *info)
+{
+ const union bpf_prog_subtype *prog_subtype;
+ enum bpf_reg_type reg_type = NOT_INIT;
+ int max_size = 0;
+
+ if (WARN_ON(!prog->aux->extra))
+ return false;
+ prog_subtype = &prog->aux->extra->subtype;
+
+ if (off < 0)
+ return false;
+ if (size <= 0 || size > sizeof(__u64))
+ return false;
+
+ /* check memory range access */
+ switch (reg_type) {
+ case NOT_INIT:
+ return false;
+ case SCALAR_VALUE:
+ /* allow partial raw value */
+ if (size > max_size)
+ return false;
+ info->ctx_field_size = max_size;
+ break;
+ default:
+ /* deny partial pointer */
+ if (size != max_size)
+ return false;
+ }
+
+ info->reg_type = reg_type;
+ return true;
+}
+
+static bool bpf_landlock_is_valid_subtype(struct bpf_prog_extra *prog_extra)
+{
+ const union bpf_prog_subtype *subtype;
+
+ if (!prog_extra)
+ return false;
+ subtype = &prog_extra->subtype;
+
+ switch (subtype->landlock_hook.type) {
+ case LANDLOCK_HOOK_FS_PICK:
+ if (!subtype->landlock_hook.triggers ||
+ subtype->landlock_hook.triggers &
+ ~_LANDLOCK_TRIGGER_FS_PICK_MASK)
+ return false;
+ break;
+ case LANDLOCK_HOOK_FS_WALK:
+ if (subtype->landlock_hook.triggers)
+ return false;
+ break;
+ default:
+ return false;
+ }
+
+ return true;
+}
+
+static const struct bpf_func_proto *bpf_landlock_func_proto(
+ enum bpf_func_id func_id,
+ const struct bpf_prog *prog)
+{
+ u64 hook_type;
+
+ if (WARN_ON(!prog->aux->extra))
+ return NULL;
+ hook_type = prog->aux->extra->subtype.landlock_hook.type;
+
+ /* generic functions */
+ /* TODO: do we need/want update/delete functions for every LL prog?
+ * => impurity vs. audit */
+ switch (func_id) {
+ case BPF_FUNC_map_lookup_elem:
+ return &bpf_map_lookup_elem_proto;
+ case BPF_FUNC_map_update_elem:
+ return &bpf_map_update_elem_proto;
+ case BPF_FUNC_map_delete_elem:
+ return &bpf_map_delete_elem_proto;
+ default:
+ break;
+ }
+ return NULL;
+}
+
+const struct bpf_verifier_ops landlock_verifier_ops = {
+ .get_func_proto = bpf_landlock_func_proto,
+ .is_valid_access = bpf_landlock_is_valid_access,
+ .is_valid_subtype = bpf_landlock_is_valid_subtype,
+};
+
+const struct bpf_prog_ops landlock_prog_ops = {};
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index ddae50373d58..50145d448bc3 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -170,6 +170,7 @@ enum bpf_prog_type {
BPF_PROG_TYPE_FLOW_DISSECTOR,
BPF_PROG_TYPE_CGROUP_SYSCTL,
BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE,
+ BPF_PROG_TYPE_LANDLOCK_HOOK,
};
enum bpf_attach_type {
diff --git a/tools/include/uapi/linux/landlock.h b/tools/include/uapi/linux/landlock.h
new file mode 100644
index 000000000000..9e6d8e10ec2c
--- /dev/null
+++ b/tools/include/uapi/linux/landlock.h
@@ -0,0 +1,109 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Landlock - UAPI headers
+ *
+ * Copyright © 2017-2019 Mickaël Salaün <mic@digikod.net>
+ * Copyright © 2018-2019 ANSSI
+ */
+
+#ifndef _UAPI__LINUX_LANDLOCK_H__
+#define _UAPI__LINUX_LANDLOCK_H__
+
+#include <linux/types.h>
+
+#define LANDLOCK_RET_ALLOW 0
+#define LANDLOCK_RET_DENY 1
+
+/**
+ * enum landlock_hook_type - hook type for which a Landlock program is called
+ *
+ * A hook is a policy decision point which exposes the same context type for
+ * each program evaluation.
+ *
+ * @LANDLOCK_HOOK_FS_PICK: called for the last element of a file path
+ * @LANDLOCK_HOOK_FS_WALK: called for each directory of a file path (excluding
+ * the directory passed to fs_pick, if any)
+ */
+enum landlock_hook_type {
+ LANDLOCK_HOOK_FS_PICK = 1,
+ LANDLOCK_HOOK_FS_WALK,
+};
+
+/**
+ * DOC: landlock_triggers
+ *
+ * A landlock trigger is used as a bitmask in subtype.landlock_hook.triggers
+ * for a fs_pick program. It defines a set of actions for which the program
+ * should verify an access request.
+ *
+ * - %LANDLOCK_TRIGGER_FS_PICK_APPEND
+ * - %LANDLOCK_TRIGGER_FS_PICK_CHDIR
+ * - %LANDLOCK_TRIGGER_FS_PICK_CHROOT
+ * - %LANDLOCK_TRIGGER_FS_PICK_CREATE
+ * - %LANDLOCK_TRIGGER_FS_PICK_EXECUTE
+ * - %LANDLOCK_TRIGGER_FS_PICK_FCNTL
+ * - %LANDLOCK_TRIGGER_FS_PICK_GETATTR
+ * - %LANDLOCK_TRIGGER_FS_PICK_IOCTL
+ * - %LANDLOCK_TRIGGER_FS_PICK_LINK
+ * - %LANDLOCK_TRIGGER_FS_PICK_LINKTO
+ * - %LANDLOCK_TRIGGER_FS_PICK_LOCK
+ * - %LANDLOCK_TRIGGER_FS_PICK_MAP
+ * - %LANDLOCK_TRIGGER_FS_PICK_MOUNTON
+ * - %LANDLOCK_TRIGGER_FS_PICK_OPEN
+ * - %LANDLOCK_TRIGGER_FS_PICK_READ
+ * - %LANDLOCK_TRIGGER_FS_PICK_READDIR
+ * - %LANDLOCK_TRIGGER_FS_PICK_RECEIVE
+ * - %LANDLOCK_TRIGGER_FS_PICK_RENAME
+ * - %LANDLOCK_TRIGGER_FS_PICK_RENAMETO
+ * - %LANDLOCK_TRIGGER_FS_PICK_RMDIR
+ * - %LANDLOCK_TRIGGER_FS_PICK_SETATTR
+ * - %LANDLOCK_TRIGGER_FS_PICK_TRANSFER
+ * - %LANDLOCK_TRIGGER_FS_PICK_UNLINK
+ * - %LANDLOCK_TRIGGER_FS_PICK_WRITE
+ */
+#define LANDLOCK_TRIGGER_FS_PICK_APPEND (1ULL << 0)
+#define LANDLOCK_TRIGGER_FS_PICK_CHDIR (1ULL << 1)
+#define LANDLOCK_TRIGGER_FS_PICK_CHROOT (1ULL << 2)
+#define LANDLOCK_TRIGGER_FS_PICK_CREATE (1ULL << 3)
+#define LANDLOCK_TRIGGER_FS_PICK_EXECUTE (1ULL << 4)
+#define LANDLOCK_TRIGGER_FS_PICK_FCNTL (1ULL << 5)
+#define LANDLOCK_TRIGGER_FS_PICK_GETATTR (1ULL << 6)
+#define LANDLOCK_TRIGGER_FS_PICK_IOCTL (1ULL << 7)
+#define LANDLOCK_TRIGGER_FS_PICK_LINK (1ULL << 8)
+#define LANDLOCK_TRIGGER_FS_PICK_LINKTO (1ULL << 9)
+#define LANDLOCK_TRIGGER_FS_PICK_LOCK (1ULL << 10)
+#define LANDLOCK_TRIGGER_FS_PICK_MAP (1ULL << 11)
+#define LANDLOCK_TRIGGER_FS_PICK_MOUNTON (1ULL << 12)
+#define LANDLOCK_TRIGGER_FS_PICK_OPEN (1ULL << 13)
+#define LANDLOCK_TRIGGER_FS_PICK_READ (1ULL << 14)
+#define LANDLOCK_TRIGGER_FS_PICK_READDIR (1ULL << 15)
+#define LANDLOCK_TRIGGER_FS_PICK_RECEIVE (1ULL << 16)
+#define LANDLOCK_TRIGGER_FS_PICK_RENAME (1ULL << 17)
+#define LANDLOCK_TRIGGER_FS_PICK_RENAMETO (1ULL << 18)
+#define LANDLOCK_TRIGGER_FS_PICK_RMDIR (1ULL << 19)
+#define LANDLOCK_TRIGGER_FS_PICK_SETATTR (1ULL << 20)
+#define LANDLOCK_TRIGGER_FS_PICK_TRANSFER (1ULL << 21)
+#define LANDLOCK_TRIGGER_FS_PICK_UNLINK (1ULL << 22)
+#define LANDLOCK_TRIGGER_FS_PICK_WRITE (1ULL << 23)
+
+/**
+ * struct landlock_ctx_fs_pick - context accessible to a fs_pick program
+ *
+ * @inode: pointer to the current kernel object that can be used to compare
+ * inodes from an inode map.
+ */
+struct landlock_ctx_fs_pick {
+ __u64 inode;
+};
+
+/**
+ * struct landlock_ctx_fs_walk - context accessible to a fs_walk program
+ *
+ * @inode: pointer to the current kernel object that can be used to compare
+ * inodes from an inode map.
+ */
+struct landlock_ctx_fs_walk {
+ __u64 inode;
+};
+
+#endif /* _UAPI__LINUX_LANDLOCK_H__ */
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 68f45a96769f..1b99c8da7a67 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -2646,6 +2646,7 @@ static bool bpf_prog_type__needs_kver(enum bpf_prog_type type)
case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
case BPF_PROG_TYPE_PERF_EVENT:
case BPF_PROG_TYPE_CGROUP_SYSCTL:
+ case BPF_PROG_TYPE_LANDLOCK_HOOK:
return false;
case BPF_PROG_TYPE_KPROBE:
default:
diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c
index 6635a31a7a16..f4f34cb8869a 100644
--- a/tools/lib/bpf/libbpf_probes.c
+++ b/tools/lib/bpf/libbpf_probes.c
@@ -101,6 +101,7 @@ probe_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns,
case BPF_PROG_TYPE_SK_REUSEPORT:
case BPF_PROG_TYPE_FLOW_DISSECTOR:
case BPF_PROG_TYPE_CGROUP_SYSCTL:
+ case BPF_PROG_TYPE_LANDLOCK_HOOK:
default:
break;
}
--
2.20.1
^ permalink raw reply related
* [PATCH bpf-next v9 08/10] bpf: Add a Landlock sandbox example
From: Mickaël Salaün @ 2019-06-25 21:52 UTC (permalink / raw)
To: linux-kernel
Cc: Mickaël Salaün, Aleksa Sarai, Alexander Viro,
Alexei Starovoitov, Andrew Morton, Andy Lutomirski,
Arnaldo Carvalho de Melo, Casey Schaufler, Daniel Borkmann,
David Drysdale, David S . Miller, Eric W . Biederman,
James Morris, Jann Horn, John Johansen, Jonathan Corbet,
Kees Cook, Michael Kerrisk, Mickaël Salaün, Paul Moore,
Sargun Dhillon, Serge E . Hallyn, Shuah Khan, Stephen Smalley,
Tejun Heo, Tetsuo Handa, Thomas Graf, Tycho Andersen, Will Drewry,
kernel-hardening, linux-api, linux-fsdevel, linux-security-module,
netdev
In-Reply-To: <20190625215239.11136-1-mic@digikod.net>
Add a basic sandbox tool to launch a command which is denied access to a
list of files and directories.
Add to the bpf_load library the ability to handle a BPF program subtype.
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: James Morris <jmorris@namei.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Serge E. Hallyn <serge@hallyn.com>
---
Changes since v8:
* rewrite the landlock1 sample which deny access to a set of files or
directories (i.e. simple blacklist) to fit with the previous patches
* add "landlock1" to .gitignore
* in bpf_load.c, pass the subtype with a call to
bpf_load_program_xattr()
Changes since v7:
* rewrite the example using an inode map
* add to bpf_load the ability to handle subtypes per program type
Changes since v6:
* check return value of load_and_attach()
* allow to write on pipes
* rename BPF_PROG_TYPE_LANDLOCK to BPF_PROG_TYPE_LANDLOCK_RULE
* rename Landlock version to ABI to better reflect its purpose
* use const variable (suggested by Kees Cook)
* remove useless definitions (suggested by Kees Cook)
* add detailed explanations (suggested by Kees Cook)
Changes since v5:
* cosmetic fixes
* rebase
Changes since v4:
* write Landlock rule in C and compiled it with LLVM
* remove cgroup handling
* remove path handling: only handle a read-only environment
* remove errno return codes
Changes since v3:
* remove seccomp and origin field: completely free from seccomp programs
* handle more FS-related hooks
* handle inode hooks and directory traversal
* add faked but consistent view thanks to ENOENT
* add /lib64 in the example
* fix spelling
* rename some types and definitions (e.g. SECCOMP_ADD_LANDLOCK_RULE)
Changes since v2:
* use BPF_PROG_ATTACH for cgroup handling
---
samples/bpf/.gitignore | 1 +
samples/bpf/Makefile | 3 +
samples/bpf/bpf_load.c | 76 ++++++++++++++++-
samples/bpf/bpf_load.h | 7 ++
samples/bpf/landlock1.h | 8 ++
samples/bpf/landlock1_kern.c | 104 +++++++++++++++++++++++
samples/bpf/landlock1_user.c | 157 +++++++++++++++++++++++++++++++++++
7 files changed, 352 insertions(+), 4 deletions(-)
create mode 100644 samples/bpf/landlock1.h
create mode 100644 samples/bpf/landlock1_kern.c
create mode 100644 samples/bpf/landlock1_user.c
diff --git a/samples/bpf/.gitignore b/samples/bpf/.gitignore
index 74d31fd3c99c..a4c9c806f739 100644
--- a/samples/bpf/.gitignore
+++ b/samples/bpf/.gitignore
@@ -2,6 +2,7 @@ cpustat
fds_example
hbm
ibumad
+landlock1
lathist
lwt_len_hist
map_perf_test
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 0917f8cf4fab..da246eaa8bf8 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -53,6 +53,7 @@ hostprogs-y += task_fd_query
hostprogs-y += xdp_sample_pkts
hostprogs-y += ibumad
hostprogs-y += hbm
+hostprogs-y += landlock1
# Libbpf dependencies
LIBBPF = $(TOOLS_PATH)/lib/bpf/libbpf.a
@@ -109,6 +110,7 @@ task_fd_query-objs := bpf_load.o task_fd_query_user.o $(TRACE_HELPERS)
xdp_sample_pkts-objs := xdp_sample_pkts_user.o $(TRACE_HELPERS)
ibumad-objs := bpf_load.o ibumad_user.o $(TRACE_HELPERS)
hbm-objs := bpf_load.o hbm.o $(CGROUP_HELPERS)
+landlock1-objs := bpf_load.o landlock1_user.o
# Tell kbuild to always build the programs
always := $(hostprogs-y)
@@ -168,6 +170,7 @@ always += task_fd_query_kern.o
always += xdp_sample_pkts_kern.o
always += ibumad_kern.o
always += hbm_out_kern.o
+always += landlock1_kern.o
KBUILD_HOSTCFLAGS += -I$(objtree)/usr/include
KBUILD_HOSTCFLAGS += -I$(srctree)/tools/lib/bpf/
diff --git a/samples/bpf/bpf_load.c b/samples/bpf/bpf_load.c
index 4574b1939e49..bf62d965f606 100644
--- a/samples/bpf/bpf_load.c
+++ b/samples/bpf/bpf_load.c
@@ -12,6 +12,7 @@
#include <stdlib.h>
#include <linux/bpf.h>
#include <linux/filter.h>
+#include <linux/landlock.h>
#include <linux/perf_event.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
@@ -42,6 +43,9 @@ int prog_array_fd = -1;
struct bpf_map_data map_data[MAX_MAPS];
int map_data_count;
+struct bpf_subtype_data subtype_data[MAX_PROGS];
+int subtype_data_count;
+
static int populate_prog_array(const char *event, int prog_fd)
{
int ind = atoi(event), err;
@@ -87,11 +91,15 @@ static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
bool is_sockops = strncmp(event, "sockops", 7) == 0;
bool is_sk_skb = strncmp(event, "sk_skb", 6) == 0;
bool is_sk_msg = strncmp(event, "sk_msg", 6) == 0;
+ bool is_landlock = strncmp(event, "landlock", 8) == 0;
size_t insns_cnt = size / sizeof(struct bpf_insn);
enum bpf_prog_type prog_type;
char buf[256];
int fd, efd, err, id;
struct perf_event_attr attr = {};
+ union bpf_prog_subtype *st = NULL;
+ struct bpf_subtype_data *sd = NULL;
+ struct bpf_load_program_attr load_attr;
attr.type = PERF_TYPE_TRACEPOINT;
attr.sample_type = PERF_SAMPLE_RAW;
@@ -120,6 +128,32 @@ static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
prog_type = BPF_PROG_TYPE_SK_SKB;
} else if (is_sk_msg) {
prog_type = BPF_PROG_TYPE_SK_MSG;
+ } else if (is_landlock) {
+ int i, prog_id;
+ const char *event_id = (event + 8);
+
+ if (!isdigit(*event_id)) {
+ printf("invalid prog number\n");
+ return -1;
+ }
+ prog_id = atoi(event_id);
+ for (i = 0; i < subtype_data_count; i++) {
+ if (subtype_data[i].name && strcmp(event,
+ subtype_data[i].name) == 0) {
+ /* save the prog_id for a next program */
+ sd = &subtype_data[i];
+ sd->prog_id = prog_id;
+ st = &sd->subtype;
+ free(sd->name);
+ sd->name = NULL;
+ break;
+ }
+ }
+ if (!st) {
+ printf("missing subtype\n");
+ return -1;
+ }
+ prog_type = BPF_PROG_TYPE_LANDLOCK_HOOK;
} else {
printf("Unknown event '%s'\n", event);
return -1;
@@ -128,16 +162,25 @@ static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
if (prog_cnt == MAX_PROGS)
return -1;
- fd = bpf_load_program(prog_type, prog, insns_cnt, license, kern_version,
- bpf_log_buf, BPF_LOG_BUF_SIZE);
+ memset(&load_attr, 0, sizeof(struct bpf_load_program_attr));
+ load_attr.prog_type = prog_type;
+ load_attr.prog_subtype = st;
+ load_attr.insns = prog;
+ load_attr.insns_cnt = insns_cnt;
+ load_attr.license = license;
+ load_attr.kern_version = kern_version;
+ fd = bpf_load_program_xattr(&load_attr, bpf_log_buf, BPF_LOG_BUF_SIZE);
if (fd < 0) {
printf("bpf_load_program() err=%d\n%s", errno, bpf_log_buf);
return -1;
}
+ if (sd)
+ sd->prog_fd = fd;
prog_fd[prog_cnt++] = fd;
- if (is_xdp || is_perf_event || is_cgroup_skb || is_cgroup_sk)
+ if (is_xdp || is_perf_event || is_cgroup_skb || is_cgroup_sk ||
+ is_landlock)
return 0;
if (is_socket || is_sockops || is_sk_skb || is_sk_msg) {
@@ -519,6 +562,7 @@ static int do_load_bpf_file(const char *path, fixup_map_cb fixup_map)
kern_version = 0;
memset(license, 0, sizeof(license));
memset(processed_sec, 0, sizeof(processed_sec));
+ subtype_data_count = 0;
if (elf_version(EV_CURRENT) == EV_NONE)
return 1;
@@ -567,6 +611,29 @@ static int do_load_bpf_file(const char *path, fixup_map_cb fixup_map)
data_maps = data;
for (j = 0; j < MAX_MAPS; j++)
map_data[j].fd = -1;
+ } else if (strncmp(shname, "subtype", 7) == 0) {
+ processed_sec[i] = true;
+ if (*(shname + 7) != '/') {
+ printf("invalid name of subtype section");
+ return 1;
+ }
+ if (data->d_size != sizeof(union bpf_prog_subtype)) {
+ printf("invalid size of subtype section: %zd\n",
+ data->d_size);
+ printf("ref: %zd\n",
+ sizeof(union bpf_prog_subtype));
+ return 1;
+ }
+ if (subtype_data_count >= MAX_PROGS) {
+ printf("too many subtype sections");
+ return 1;
+ }
+ memcpy(&subtype_data[subtype_data_count].subtype,
+ data->d_buf,
+ sizeof(union bpf_prog_subtype));
+ subtype_data[subtype_data_count].name =
+ strdup((shname + 8));
+ subtype_data_count++;
} else if (shdr.sh_type == SHT_SYMTAB) {
strtabidx = shdr.sh_link;
symbols = data;
@@ -643,7 +710,8 @@ static int do_load_bpf_file(const char *path, fixup_map_cb fixup_map)
memcmp(shname, "cgroup/", 7) == 0 ||
memcmp(shname, "sockops", 7) == 0 ||
memcmp(shname, "sk_skb", 6) == 0 ||
- memcmp(shname, "sk_msg", 6) == 0) {
+ memcmp(shname, "sk_msg", 6) == 0 ||
+ memcmp(shname, "landlock", 8) == 0) {
ret = load_and_attach(shname, data->d_buf,
data->d_size);
if (ret != 0)
diff --git a/samples/bpf/bpf_load.h b/samples/bpf/bpf_load.h
index 814894a12974..e210b5fdf8ee 100644
--- a/samples/bpf/bpf_load.h
+++ b/samples/bpf/bpf_load.h
@@ -24,6 +24,13 @@ struct bpf_map_data {
struct bpf_load_map_def def;
};
+struct bpf_subtype_data {
+ char *name;
+ int prog_id;
+ int prog_fd;
+ union bpf_prog_subtype subtype;
+};
+
typedef void (*fixup_map_cb)(struct bpf_map_data *map, int idx);
extern int prog_fd[MAX_PROGS];
diff --git a/samples/bpf/landlock1.h b/samples/bpf/landlock1.h
new file mode 100644
index 000000000000..53b0a9447855
--- /dev/null
+++ b/samples/bpf/landlock1.h
@@ -0,0 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Landlock sample 1 - common header
+ *
+ * Copyright © 2018-2019 Mickaël Salaün <mic@digikod.net>
+ */
+
+#define MAP_FLAG_DENY (1ULL << 0)
diff --git a/samples/bpf/landlock1_kern.c b/samples/bpf/landlock1_kern.c
new file mode 100644
index 000000000000..0298d98dd06a
--- /dev/null
+++ b/samples/bpf/landlock1_kern.c
@@ -0,0 +1,104 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Landlock sample 1 - whitelist of read only or read-write file hierarchy
+ *
+ * Copyright © 2017-2019 Mickaël Salaün <mic@digikod.net>
+ */
+
+/*
+ * This file contains a function that will be compiled to eBPF bytecode thanks
+ * to LLVM/Clang.
+ *
+ * Each SEC() means that the following function or variable will be part of a
+ * custom ELF section. This sections are then processed by the userspace part
+ * (see landlock1_user.c) to extract eBPF bytecode and take into account
+ * variables describing the eBPF program subtype or its license.
+ */
+
+#include <uapi/linux/bpf.h>
+#include <uapi/linux/landlock.h>
+
+#include "bpf_helpers.h"
+#include "landlock1.h" /* MAP_FLAG_DENY */
+
+#define MAP_MAX_ENTRIES 20
+
+SEC("maps")
+struct bpf_map_def inode_map = {
+ .type = BPF_MAP_TYPE_INODE,
+ .key_size = sizeof(u32),
+ .value_size = sizeof(u64),
+ .max_entries = MAP_MAX_ENTRIES,
+};
+
+static __always_inline __u64 get_access(void *inode)
+{
+ if (bpf_inode_map_lookup(&inode_map, inode) & MAP_FLAG_DENY)
+ return LANDLOCK_RET_DENY;
+ return LANDLOCK_RET_ALLOW;
+}
+
+SEC("subtype/landlock1")
+static union bpf_prog_subtype _subtype1 = {
+ .landlock_hook = {
+ .type = LANDLOCK_HOOK_FS_WALK,
+ }
+};
+
+/*
+ * The function fs_walk() is a simple Landlock program enforced on a set of
+ * processes. This program will be run for each walk through a file path.
+ *
+ * The argument ctx contains the context of the program when it is run, which
+ * enable to evaluate the file path. This context can change for each run of
+ * the program.
+ */
+SEC("landlock1")
+int fs_walk(struct landlock_ctx_fs_walk *ctx)
+{
+ return get_access((void *)ctx->inode);
+}
+
+SEC("subtype/landlock2")
+static union bpf_prog_subtype _subtype2 = {
+ .landlock_hook = {
+ .type = LANDLOCK_HOOK_FS_PICK,
+ /*
+ * allowed:
+ * - LANDLOCK_TRIGGER_FS_PICK_LINK
+ * - LANDLOCK_TRIGGER_FS_PICK_LINKTO
+ * - LANDLOCK_TRIGGER_FS_PICK_RECEIVE
+ * - LANDLOCK_TRIGGER_FS_PICK_MOUNTON
+ */
+ .triggers =
+ LANDLOCK_TRIGGER_FS_PICK_APPEND |
+ LANDLOCK_TRIGGER_FS_PICK_CHDIR |
+ LANDLOCK_TRIGGER_FS_PICK_CHROOT |
+ LANDLOCK_TRIGGER_FS_PICK_CREATE |
+ LANDLOCK_TRIGGER_FS_PICK_EXECUTE |
+ LANDLOCK_TRIGGER_FS_PICK_FCNTL |
+ LANDLOCK_TRIGGER_FS_PICK_GETATTR |
+ LANDLOCK_TRIGGER_FS_PICK_IOCTL |
+ LANDLOCK_TRIGGER_FS_PICK_LOCK |
+ LANDLOCK_TRIGGER_FS_PICK_MAP |
+ LANDLOCK_TRIGGER_FS_PICK_OPEN |
+ LANDLOCK_TRIGGER_FS_PICK_READ |
+ LANDLOCK_TRIGGER_FS_PICK_READDIR |
+ LANDLOCK_TRIGGER_FS_PICK_RENAME |
+ LANDLOCK_TRIGGER_FS_PICK_RENAMETO |
+ LANDLOCK_TRIGGER_FS_PICK_RMDIR |
+ LANDLOCK_TRIGGER_FS_PICK_SETATTR |
+ LANDLOCK_TRIGGER_FS_PICK_TRANSFER |
+ LANDLOCK_TRIGGER_FS_PICK_UNLINK |
+ LANDLOCK_TRIGGER_FS_PICK_WRITE,
+ }
+};
+
+SEC("landlock2")
+int fs_pick_ro(struct landlock_ctx_fs_pick *ctx)
+{
+ return get_access((void *)ctx->inode);
+}
+
+SEC("license")
+static const char _license[] = "GPL";
diff --git a/samples/bpf/landlock1_user.c b/samples/bpf/landlock1_user.c
new file mode 100644
index 000000000000..aa45932d36a8
--- /dev/null
+++ b/samples/bpf/landlock1_user.c
@@ -0,0 +1,157 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Landlock sample 1 - deny access to a set of directories (blacklisting)
+ *
+ * Copyright © 2017-2019 Mickaël Salaün <mic@digikod.net>
+ */
+
+#include "bpf/libbpf.h"
+#include "bpf_load.h"
+#include "landlock1.h" /* MAP_FLAG_DENY */
+
+#define _GNU_SOURCE
+#include <errno.h>
+#include <fcntl.h> /* open() */
+#include <linux/bpf.h>
+#include <linux/filter.h>
+#include <linux/landlock.h>
+#include <linux/prctl.h>
+#include <linux/seccomp.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/prctl.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+#ifndef seccomp
+static int seccomp(unsigned int op, unsigned int flags, void *args)
+{
+ errno = 0;
+ return syscall(__NR_seccomp, op, flags, args);
+}
+#endif
+
+static int apply_sandbox(int prog_fd)
+{
+ int ret = 0;
+
+ /* set up the test sandbox */
+ if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) {
+ perror("prctl(no_new_priv)");
+ return 1;
+ }
+ if (seccomp(SECCOMP_PREPEND_LANDLOCK_PROG, 0, &prog_fd)) {
+ perror("seccomp(set_hook)");
+ ret = 1;
+ }
+ close(prog_fd);
+
+ return ret;
+}
+
+#define ENV_FS_PATH_DENY_NAME "LL_PATH_DENY"
+#define ENV_PATH_TOKEN ":"
+
+static int parse_path(char *env_path, const char ***path_list)
+{
+ int i, path_nb = 0;
+
+ if (env_path) {
+ path_nb++;
+ for (i = 0; env_path[i]; i++) {
+ if (env_path[i] == ENV_PATH_TOKEN[0])
+ path_nb++;
+ }
+ }
+ *path_list = malloc(path_nb * sizeof(**path_list));
+ for (i = 0; i < path_nb; i++)
+ (*path_list)[i] = strsep(&env_path, ENV_PATH_TOKEN);
+
+ return path_nb;
+}
+
+static int populate_map(const char *env_var, unsigned long long value,
+ int map_fd)
+{
+ int path_nb, ref_fd, i;
+ char *env_path_name;
+ const char **path_list = NULL;
+
+ env_path_name = getenv(env_var);
+ if (!env_path_name)
+ return 0;
+ env_path_name = strdup(env_path_name);
+ path_nb = parse_path(env_path_name, &path_list);
+
+ for (i = 0; i < path_nb; i++) {
+ ref_fd = open(path_list[i], O_RDONLY | O_CLOEXEC);
+ if (ref_fd < 0) {
+ fprintf(stderr, "Failed to open \"%s\": %s\n",
+ path_list[i],
+ strerror(errno));
+ return 1;
+ }
+ if (bpf_map_update_elem(map_fd, &ref_fd, &value, BPF_ANY)) {
+ fprintf(stderr, "Failed to update the map with"
+ " \"%s\": %s\n", path_list[i],
+ strerror(errno));
+ return 1;
+ }
+ close(ref_fd);
+ }
+ free(env_path_name);
+ return 0;
+}
+
+int main(int argc, char * const argv[], char * const *envp)
+{
+ char filename[256];
+ char *cmd_path;
+ char * const *cmd_argv;
+ int ll_prog_walk, ll_prog_pick;
+
+ if (argc < 2) {
+ fprintf(stderr, "usage: %s <cmd> [args]...\n\n", argv[0]);
+ fprintf(stderr, "Launch a command in a restricted environment.\n\n");
+ fprintf(stderr, "Environment variables containing paths, each separated by a colon:\n");
+ fprintf(stderr, "* %s: list of files and directories which are denied\n",
+ ENV_FS_PATH_DENY_NAME);
+ fprintf(stderr, "\nexample:\n"
+ "%s=\"${HOME}/.ssh:${HOME}/Images\" "
+ "%s /bin/sh -i\n",
+ ENV_FS_PATH_DENY_NAME, argv[0]);
+ return 1;
+ }
+
+ snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+ if (load_bpf_file(filename)) {
+ printf("%s", bpf_log_buf);
+ return 1;
+ }
+ ll_prog_walk = prog_fd[0]; /* fs_walk */
+ ll_prog_pick = prog_fd[1]; /* fs_pick */
+ if (!ll_prog_walk || !ll_prog_pick) {
+ if (errno)
+ printf("load_bpf_file: %s\n", strerror(errno));
+ else
+ printf("load_bpf_file: Error\n");
+ return 1;
+ }
+
+ if (populate_map(ENV_FS_PATH_DENY_NAME, MAP_FLAG_DENY, map_fd[0]))
+ return 1;
+ close(map_fd[0]);
+
+ fprintf(stderr, "Launching a new sandboxed process\n");
+ if (apply_sandbox(ll_prog_walk))
+ return 1;
+ if (apply_sandbox(ll_prog_pick))
+ return 1;
+ cmd_path = argv[1];
+ cmd_argv = argv + 1;
+ execve(cmd_path, cmd_argv, envp);
+ perror("Failed to call execve");
+ return 1;
+}
--
2.20.1
^ permalink raw reply related
* [PATCH bpf-next v9 10/10] landlock: Add user and kernel documentation for Landlock
From: Mickaël Salaün @ 2019-06-25 21:52 UTC (permalink / raw)
To: linux-kernel
Cc: Mickaël Salaün, Aleksa Sarai, Alexander Viro,
Alexei Starovoitov, Andrew Morton, Andy Lutomirski,
Arnaldo Carvalho de Melo, Casey Schaufler, Daniel Borkmann,
David Drysdale, David S . Miller, Eric W . Biederman,
James Morris, Jann Horn, John Johansen, Jonathan Corbet,
Kees Cook, Michael Kerrisk, Mickaël Salaün, Paul Moore,
Sargun Dhillon, Serge E . Hallyn, Shuah Khan, Stephen Smalley,
Tejun Heo, Tetsuo Handa, Thomas Graf, Tycho Andersen, Will Drewry,
kernel-hardening, linux-api, linux-fsdevel, linux-security-module,
netdev
In-Reply-To: <20190625215239.11136-1-mic@digikod.net>
This documentation can be built with the Sphinx framework.
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: James Morris <jmorris@namei.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Serge E. Hallyn <serge@hallyn.com>
---
Changes since v8:
* remove documentation related to chaining and tagging according to this
patch series
Changes since v7:
* update documentation according to the Landlock revamp
Changes since v6:
* add a check for ctx->event
* rename BPF_PROG_TYPE_LANDLOCK to BPF_PROG_TYPE_LANDLOCK_RULE
* rename Landlock version to ABI to better reflect its purpose and add a
dedicated changelog section
* update tables
* relax no_new_privs recommendations
* remove ABILITY_WRITE related functions
* reword rule "appending" to "prepending" and explain it
* cosmetic fixes
Changes since v5:
* update the rule hierarchy inheritance explanation
* briefly explain ctx->arg2
* add ptrace restrictions
* explain EPERM
* update example (subtype)
* use ":manpage:"
---
Documentation/security/index.rst | 1 +
Documentation/security/landlock/index.rst | 20 +++
Documentation/security/landlock/kernel.rst | 99 ++++++++++++++
Documentation/security/landlock/user.rst | 148 +++++++++++++++++++++
4 files changed, 268 insertions(+)
create mode 100644 Documentation/security/landlock/index.rst
create mode 100644 Documentation/security/landlock/kernel.rst
create mode 100644 Documentation/security/landlock/user.rst
diff --git a/Documentation/security/index.rst b/Documentation/security/index.rst
index aad6d92ffe31..32b4c1db2325 100644
--- a/Documentation/security/index.rst
+++ b/Documentation/security/index.rst
@@ -12,3 +12,4 @@ Security Documentation
SCTP
self-protection
tpm/index
+ landlock/index
diff --git a/Documentation/security/landlock/index.rst b/Documentation/security/landlock/index.rst
new file mode 100644
index 000000000000..d0af868d1582
--- /dev/null
+++ b/Documentation/security/landlock/index.rst
@@ -0,0 +1,20 @@
+=========================================
+Landlock LSM: programmatic access control
+=========================================
+
+Landlock is a stackable Linux Security Module (LSM) that makes it possible to
+create security sandboxes, programmable access-controls or safe endpoint
+security agents. This kind of sandbox is expected to help mitigate the
+security impact of bugs or unexpected/malicious behaviors in user-space
+applications. The current version allows only a process with the global
+CAP_SYS_ADMIN capability to create such sandboxes but the ultimate goal of
+Landlock is to empower any process, including unprivileged ones, to securely
+restrict themselves. Landlock is inspired by seccomp-bpf but instead of
+filtering syscalls and their raw arguments, a Landlock rule can inspect the use
+of kernel objects like files and hence make a decision according to the kernel
+semantic.
+
+.. toctree::
+
+ user
+ kernel
diff --git a/Documentation/security/landlock/kernel.rst b/Documentation/security/landlock/kernel.rst
new file mode 100644
index 000000000000..7d1e06d544bf
--- /dev/null
+++ b/Documentation/security/landlock/kernel.rst
@@ -0,0 +1,99 @@
+==============================
+Landlock: kernel documentation
+==============================
+
+eBPF properties
+===============
+
+To get an expressive language while still being safe and small, Landlock is
+based on eBPF. Landlock should be usable by untrusted processes and must
+therefore expose a minimal attack surface. The eBPF bytecode is minimal,
+powerful, widely used and designed to be used by untrusted applications. Thus,
+reusing the eBPF support in the kernel enables a generic approach while
+minimizing new code.
+
+An eBPF program has access to an eBPF context containing some fields used to
+inspect the current object. These arguments can be used directly (e.g. cookie)
+or passed to helper functions according to their types (e.g. inode pointer). It
+is then possible to do complex access checks without race conditions or
+inconsistent evaluation (i.e. `incorrect mirroring of the OS code and state
+<https://www.ndss-symposium.org/ndss2003/traps-and-pitfalls-practical-problems-system-call-interposition-based-security-tools/>`_).
+
+A Landlock hook describes a particular access type. For now, there is two
+hooks dedicated to filesystem related operations: LANDLOCK_HOOK_FS_PICK and
+LANDLOCK_HOOK_FS_WALK. A Landlock program is tied to one hook. This makes it
+possible to statically check context accesses, potentially performed by such
+program, and hence prevents kernel address leaks and ensure the right use of
+hook arguments with eBPF functions. Any user can add multiple Landlock
+programs per Landlock hook. They are stacked and evaluated one after the
+other, starting from the most recent program, as seccomp-bpf does with its
+filters. Underneath, a hook is an abstraction over a set of LSM hooks.
+
+
+Guiding principles
+==================
+
+Unprivileged use
+----------------
+
+* Landlock helpers and context should be usable by any unprivileged and
+ untrusted program while following the system security policy enforced by
+ other access control mechanisms (e.g. DAC, LSM).
+
+
+Landlock hook and context
+-------------------------
+
+* A Landlock hook shall be focused on access control on kernel objects instead
+ of syscall filtering (i.e. syscall arguments), which is the purpose of
+ seccomp-bpf.
+* A Landlock context provided by a hook shall express the minimal and more
+ generic interface to control an access for a kernel object.
+* A hook shall guaranty that all the BPF function calls from a program are
+ safe. Thus, the related Landlock context arguments shall always be of the
+ same type for a particular hook. For example, a network hook could share
+ helpers with a file hook because of UNIX socket. However, the same helpers
+ may not be compatible for a file system handle and a net handle.
+* Multiple hooks may use the same context interface.
+
+
+Landlock helpers
+----------------
+
+* Landlock helpers shall be as generic as possible while at the same time being
+ as simple as possible and following the syscall creation principles (cf.
+ *Documentation/adding-syscalls.txt*).
+* The only behavior change allowed on a helper is to fix a (logical) bug to
+ match the initial semantic.
+* Helpers shall be reentrant, i.e. only take inputs from arguments (e.g. from
+ the BPF context), to enable a hook to use a cache. Future program options
+ might change this cache behavior.
+* It is quite easy to add new helpers to extend Landlock. The main concern
+ should be about the possibility to leak information from the kernel that may
+ not be accessible otherwise (i.e. side-channel attack).
+
+
+Questions and answers
+=====================
+
+Why not create a custom hook for each kind of action?
+-----------------------------------------------------
+
+Landlock programs can handle these checks. Adding more exceptions to the
+kernel code would lead to more code complexity. A decision to ignore a kind of
+action can and should be done at the beginning of a Landlock program.
+
+
+Why a program does not return an errno or a kill code?
+------------------------------------------------------
+
+seccomp filters can return multiple kind of code, including an errno value or a
+kill signal, which may be convenient for access control. Those return codes
+are hardwired in the userland ABI. Instead, Landlock's approach is to return a
+boolean to allow or deny an action, which is much simpler and more generic.
+Moreover, we do not really have a choice because, unlike to seccomp, Landlock
+programs are not enforced at the syscall entry point but may be executed at any
+point in the kernel (through LSM hooks) where an errno return code may not make
+sense. However, with this simple ABI and with the ability to call helpers,
+Landlock may gain features similar to seccomp-bpf in the future while being
+compatible with previous programs.
diff --git a/Documentation/security/landlock/user.rst b/Documentation/security/landlock/user.rst
new file mode 100644
index 000000000000..e4bb7dba4aa7
--- /dev/null
+++ b/Documentation/security/landlock/user.rst
@@ -0,0 +1,148 @@
+================================
+Landlock: userland documentation
+================================
+
+Landlock programs
+=================
+
+eBPF programs are used to create security programs. They are contained and can
+call only a whitelist of dedicated functions. Moreover, they can only loop
+under strict conditions, which protects from denial of service. More
+information on BPF can be found in *Documentation/networking/filter.txt*.
+
+
+Writing a program
+-----------------
+
+To enforce a security policy, a thread first needs to create a Landlock program.
+The easiest way to write an eBPF program depicting a security program is to write
+it in the C language. As described in *samples/bpf/README.rst*, LLVM can
+compile such programs. Files *samples/bpf/landlock1_kern.c* and those in
+*tools/testing/selftests/landlock/* can be used as examples.
+
+Once the eBPF program is created, the next step is to create the metadata
+describing the Landlock program. This metadata includes a subtype which
+contains the hook type to which the program is tied and some options.
+
+.. code-block:: c
+
+ union bpf_prog_subtype subtype = {
+ .landlock_hook = {
+ .type = LANDLOCK_HOOK_FS_PICK,
+ .triggers = LANDLOCK_TRIGGER_FS_PICK_OPEN,
+ }
+ };
+
+A Landlock hook describes the kind of kernel object for which a program will be
+triggered to allow or deny an action. For example, the hook
+LANDLOCK_HOOK_FS_PICK can be triggered every time a landlocked thread performs
+a set of action related to the filesystem (e.g. open, read, write, mount...).
+This actions are identified by the `triggers` bitfield.
+
+The next step is to fill a :c:type:`union bpf_attr <bpf_attr>` with
+BPF_PROG_TYPE_LANDLOCK_HOOK, the previously created subtype and other BPF
+program metadata. This bpf_attr must then be passed to the :manpage:`bpf(2)`
+syscall alongside the BPF_PROG_LOAD command. If everything is deemed correct
+by the kernel, the thread gets a file descriptor referring to this program.
+
+In the following code, the *insn* variable is an array of BPF instructions
+which can be extracted from an ELF file as is done in bpf_load_file() from
+*samples/bpf/bpf_load.c*.
+
+.. code-block:: c
+
+ union bpf_attr attr = {
+ .prog_type = BPF_PROG_TYPE_LANDLOCK_HOOK,
+ .insn_cnt = sizeof(insn) / sizeof(struct bpf_insn),
+ .insns = (__u64) (unsigned long) insn,
+ .license = (__u64) (unsigned long) "GPL",
+ .prog_subtype = &subtype,
+ .prog_subtype_size = sizeof(subtype),
+ };
+ int fd = bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
+ if (fd == -1)
+ exit(1);
+
+
+Enforcing a program
+-------------------
+
+Once the Landlock program has been created or received (e.g. through a UNIX
+socket), the thread willing to sandbox itself (and its future children) should
+perform the following two steps.
+
+The thread should first request to never be allowed to get new privileges with a
+call to :manpage:`prctl(2)` and the PR_SET_NO_NEW_PRIVS option. More
+information can be found in *Documentation/prctl/no_new_privs.txt*.
+
+.. code-block:: c
+
+ if (prctl(PR_SET_NO_NEW_PRIVS, 1, NULL, 0, 0))
+ exit(1);
+
+A thread can apply a program to itself by using the :manpage:`seccomp(2)` syscall.
+The operation is SECCOMP_PREPEND_LANDLOCK_PROG, the flags must be empty and the
+*args* argument must point to a valid Landlock program file descriptor.
+
+.. code-block:: c
+
+ if (seccomp(SECCOMP_PREPEND_LANDLOCK_PROG, 0, &fd))
+ exit(1);
+
+If the syscall succeeds, the program is now enforced on the calling thread and
+will be enforced on all its subsequently created children of the thread as
+well. Once a thread is landlocked, there is no way to remove this security
+policy, only stacking more restrictions is allowed. The program evaluation is
+performed from the newest to the oldest.
+
+When a syscall ask for an action on a kernel object, if this action is denied,
+then an EACCES errno code is returned through the syscall.
+
+
+.. _inherited_programs:
+
+Inherited programs
+------------------
+
+Every new thread resulting from a :manpage:`clone(2)` inherits Landlock program
+restrictions from its parent. This is similar to the seccomp inheritance as
+described in *Documentation/prctl/seccomp_filter.txt*.
+
+
+Ptrace restrictions
+-------------------
+
+A landlocked process has less privileges than a non-landlocked process and must
+then be subject to additional restrictions when manipulating another process.
+To be allowed to use :manpage:`ptrace(2)` and related syscalls on a target
+process, a landlocked process must have a subset of the target process programs.
+
+
+Landlock structures and constants
+=================================
+
+Hook types
+----------
+
+.. kernel-doc:: include/uapi/linux/landlock.h
+ :functions: landlock_hook_type
+
+
+Contexts
+--------
+
+.. kernel-doc:: include/uapi/linux/landlock.h
+ :functions: landlock_ctx_fs_pick landlock_ctx_fs_walk landlock_ctx_fs_get
+
+
+Triggers for fs_pick
+--------------------
+
+.. kernel-doc:: include/uapi/linux/landlock.h
+ :functions: landlock_triggers
+
+
+Additional documentation
+========================
+
+See https://landlock.io
--
2.20.1
^ permalink raw reply related
* [PATCH bpf-next v9 04/10] seccomp,landlock: Enforce Landlock programs per process hierarchy
From: Mickaël Salaün @ 2019-06-25 21:52 UTC (permalink / raw)
To: linux-kernel
Cc: Mickaël Salaün, Aleksa Sarai, Alexander Viro,
Alexei Starovoitov, Andrew Morton, Andy Lutomirski,
Arnaldo Carvalho de Melo, Casey Schaufler, Daniel Borkmann,
David Drysdale, David S . Miller, Eric W . Biederman,
James Morris, Jann Horn, John Johansen, Jonathan Corbet,
Kees Cook, Michael Kerrisk, Mickaël Salaün, Paul Moore,
Sargun Dhillon, Serge E . Hallyn, Shuah Khan, Stephen Smalley,
Tejun Heo, Tetsuo Handa, Thomas Graf, Tycho Andersen, Will Drewry,
kernel-hardening, linux-api, linux-fsdevel, linux-security-module,
netdev
In-Reply-To: <20190625215239.11136-1-mic@digikod.net>
The seccomp(2) syscall can be used by a task to apply a Landlock program
to itself. As a seccomp filter, a Landlock program is enforced for the
current task and all its future children. A program is immutable and a
task can only add new restricting programs to itself, forming a list of
programss.
A Landlock program is tied to a Landlock hook. If the action on a kernel
object is allowed by the other Linux security mechanisms (e.g. DAC,
capabilities, other LSM), then a Landlock hook related to this kind of
object is triggered. The list of programs for this hook is then
evaluated. Each program return a 32-bit value which can deny the action
on a kernel object with a non-zero value. If every programs of the list
return zero, then the action on the object is allowed.
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: James Morris <jmorris@namei.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Serge E. Hallyn <serge@hallyn.com>
Cc: Will Drewry <wad@chromium.org>
Link: https://lkml.kernel.org/r/c10a503d-5e35-7785-2f3d-25ed8dd63fab@digikod.net
---
Changes since v8:
* Remove the chaining concept from the eBPF program contexts (chain and
cookie). We need to keep these subtypes this way to be able to make
them evolve, though.
Changes since v7:
* handle and verify program chains
* split and rename providers.c to enforce.c and enforce_seccomp.c
* rename LANDLOCK_SUBTYPE_* to LANDLOCK_*
Changes since v6:
* rename some functions with more accurate names to reflect that an eBPF
program for Landlock could be used for something else than a rule
* reword rule "appending" to "prepending" and explain it
* remove the superfluous no_new_privs check, only check global
CAP_SYS_ADMIN when prepending a Landlock rule (needed for containers)
* create and use {get,put}_seccomp_landlock() (suggested by Kees Cook)
* replace ifdef with static inlined function (suggested by Kees Cook)
* use get_user() (suggested by Kees Cook)
* replace atomic_t with refcount_t (requested by Kees Cook)
* move struct landlock_{rule,events} from landlock.h to common.h
* cleanup headers
Changes since v5:
* remove struct landlock_node and use a similar inheritance mechanisme
as seccomp-bpf (requested by Andy Lutomirski)
* rename SECCOMP_ADD_LANDLOCK_RULE to SECCOMP_APPEND_LANDLOCK_RULE
* rename file manager.c to providers.c
* add comments
* typo and cosmetic fixes
Changes since v4:
* merge manager and seccomp patches
* return -EFAULT in seccomp(2) when user_bpf_fd is null to easely check
if Landlock is supported
* only allow a process with the global CAP_SYS_ADMIN to use Landlock
(will be lifted in the future)
* add an early check to exit as soon as possible if the current process
does not have Landlock rules
Changes since v3:
* remove the hard link with seccomp (suggested by Andy Lutomirski and
Kees Cook):
* remove the cookie which could imply multiple evaluation of Landlock
rules
* remove the origin field in struct landlock_data
* remove documentation fix (merged upstream)
* rename the new seccomp command to SECCOMP_ADD_LANDLOCK_RULE
* internal renaming
* split commit
* new design to be able to inherit on the fly the parent rules
Changes since v2:
* Landlock programs can now be run without seccomp filter but for any
syscall (from the process) or interruption
* move Landlock related functions and structs into security/landlock/*
(to manage cgroups as well)
* fix seccomp filter handling: run Landlock programs for each of their
legitimate seccomp filter
* properly clean up all seccomp results
* cosmetic changes to ease the understanding
* fix some ifdef
---
include/linux/landlock.h | 34 ++++
include/linux/seccomp.h | 5 +
include/uapi/linux/seccomp.h | 1 +
kernel/fork.c | 8 +-
kernel/seccomp.c | 4 +
security/landlock/Makefile | 3 +-
security/landlock/common.h | 45 +++++
security/landlock/enforce.c | 272 ++++++++++++++++++++++++++++
security/landlock/enforce.h | 18 ++
security/landlock/enforce_seccomp.c | 92 ++++++++++
10 files changed, 480 insertions(+), 2 deletions(-)
create mode 100644 include/linux/landlock.h
create mode 100644 security/landlock/enforce.c
create mode 100644 security/landlock/enforce.h
create mode 100644 security/landlock/enforce_seccomp.c
diff --git a/include/linux/landlock.h b/include/linux/landlock.h
new file mode 100644
index 000000000000..8ac7942f50fc
--- /dev/null
+++ b/include/linux/landlock.h
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Landlock LSM - public kernel headers
+ *
+ * Copyright © 2016-2019 Mickaël Salaün <mic@digikod.net>
+ * Copyright © 2018-2019 ANSSI
+ */
+
+#ifndef _LINUX_LANDLOCK_H
+#define _LINUX_LANDLOCK_H
+
+#include <linux/errno.h>
+#include <linux/sched.h> /* task_struct */
+
+#if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_SECURITY_LANDLOCK)
+extern int landlock_seccomp_prepend_prog(unsigned int flags,
+ const int __user *user_bpf_fd);
+extern void put_seccomp_landlock(struct task_struct *tsk);
+extern void get_seccomp_landlock(struct task_struct *tsk);
+#else /* CONFIG_SECCOMP_FILTER && CONFIG_SECURITY_LANDLOCK */
+static inline int landlock_seccomp_prepend_prog(unsigned int flags,
+ const int __user *user_bpf_fd)
+{
+ return -EINVAL;
+}
+static inline void put_seccomp_landlock(struct task_struct *tsk)
+{
+}
+static inline void get_seccomp_landlock(struct task_struct *tsk)
+{
+}
+#endif /* CONFIG_SECCOMP_FILTER && CONFIG_SECURITY_LANDLOCK */
+
+#endif /* _LINUX_LANDLOCK_H */
diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h
index 84868d37b35d..106a0ceff3d7 100644
--- a/include/linux/seccomp.h
+++ b/include/linux/seccomp.h
@@ -11,6 +11,7 @@
#ifdef CONFIG_SECCOMP
+#include <linux/landlock.h>
#include <linux/thread_info.h>
#include <asm/seccomp.h>
@@ -22,6 +23,7 @@ struct seccomp_filter;
* system calls available to a process.
* @filter: must always point to a valid seccomp-filter or NULL as it is
* accessed without locking during system call entry.
+ * @landlock_prog_set: contains a set of Landlock programs.
*
* @filter must only be accessed from the context of current as there
* is no read locking.
@@ -29,6 +31,9 @@ struct seccomp_filter;
struct seccomp {
int mode;
struct seccomp_filter *filter;
+#if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_SECURITY_LANDLOCK)
+ struct landlock_prog_set *landlock_prog_set;
+#endif /* CONFIG_SECCOMP_FILTER && CONFIG_SECURITY_LANDLOCK */
};
#ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
diff --git a/include/uapi/linux/seccomp.h b/include/uapi/linux/seccomp.h
index 90734aa5aa36..bce6534e7feb 100644
--- a/include/uapi/linux/seccomp.h
+++ b/include/uapi/linux/seccomp.h
@@ -16,6 +16,7 @@
#define SECCOMP_SET_MODE_FILTER 1
#define SECCOMP_GET_ACTION_AVAIL 2
#define SECCOMP_GET_NOTIF_SIZES 3
+#define SECCOMP_PREPEND_LANDLOCK_PROG 4
/* Valid flags for SECCOMP_SET_MODE_FILTER */
#define SECCOMP_FILTER_FLAG_TSYNC (1UL << 0)
diff --git a/kernel/fork.c b/kernel/fork.c
index 75675b9bf6df..a1ad5e80611b 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -51,6 +51,7 @@
#include <linux/security.h>
#include <linux/hugetlb.h>
#include <linux/seccomp.h>
+#include <linux/landlock.h>
#include <linux/swap.h>
#include <linux/syscalls.h>
#include <linux/jiffies.h>
@@ -454,6 +455,7 @@ void free_task(struct task_struct *tsk)
rt_mutex_debug_task_free(tsk);
ftrace_graph_exit_task(tsk);
put_seccomp_filter(tsk);
+ put_seccomp_landlock(tsk);
arch_release_task_struct(tsk);
if (tsk->flags & PF_KTHREAD)
free_kthread_struct(tsk);
@@ -884,7 +886,10 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
* the usage counts on the error path calling free_task.
*/
tsk->seccomp.filter = NULL;
-#endif
+#ifdef CONFIG_SECURITY_LANDLOCK
+ tsk->seccomp.landlock_prog_set = NULL;
+#endif /* CONFIG_SECURITY_LANDLOCK */
+#endif /* CONFIG_SECCOMP */
setup_thread_stack(tsk, orig);
clear_user_return_notifier(tsk);
@@ -1598,6 +1603,7 @@ static void copy_seccomp(struct task_struct *p)
/* Ref-count the new filter user, and assign it. */
get_seccomp_filter(current);
+ get_seccomp_landlock(current);
p->seccomp = current->seccomp;
/*
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 811b4a86cdf6..e5005a644b23 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -41,6 +41,7 @@
#include <linux/tracehook.h>
#include <linux/uaccess.h>
#include <linux/anon_inodes.h>
+#include <linux/landlock.h>
enum notify_state {
SECCOMP_NOTIFY_INIT,
@@ -1397,6 +1398,9 @@ static long do_seccomp(unsigned int op, unsigned int flags,
return -EINVAL;
return seccomp_get_notif_sizes(uargs);
+ case SECCOMP_PREPEND_LANDLOCK_PROG:
+ return landlock_seccomp_prepend_prog(flags,
+ (const int __user *)uargs);
default:
return -EINVAL;
}
diff --git a/security/landlock/Makefile b/security/landlock/Makefile
index 7205f9a7a2ee..2a1a7082a365 100644
--- a/security/landlock/Makefile
+++ b/security/landlock/Makefile
@@ -1,3 +1,4 @@
obj-$(CONFIG_SECURITY_LANDLOCK) := landlock.o
-landlock-y := init.o
+landlock-y := init.o \
+ enforce.o enforce_seccomp.o
diff --git a/security/landlock/common.h b/security/landlock/common.h
index fd63ed1592a7..0c9b5904e7f5 100644
--- a/security/landlock/common.h
+++ b/security/landlock/common.h
@@ -23,4 +23,49 @@
#define _LANDLOCK_TRIGGER_FS_PICK_LAST LANDLOCK_TRIGGER_FS_PICK_WRITE
#define _LANDLOCK_TRIGGER_FS_PICK_MASK ((_LANDLOCK_TRIGGER_FS_PICK_LAST << 1ULL) - 1)
+extern struct lsm_blob_sizes landlock_blob_sizes;
+
+struct landlock_prog_list {
+ struct landlock_prog_list *prev;
+ struct bpf_prog *prog;
+ refcount_t usage;
+};
+
+/**
+ * struct landlock_prog_set - Landlock programs enforced on a thread
+ *
+ * This is used for low performance impact when forking a process. Instead of
+ * copying the full array and incrementing the usage of each entries, only
+ * create a pointer to &struct landlock_prog_set and increments its usage. When
+ * prepending a new program, if &struct landlock_prog_set is shared with other
+ * tasks, then duplicate it and prepend the program to this new &struct
+ * landlock_prog_set.
+ *
+ * @usage: reference count to manage the object lifetime. When a thread need to
+ * add Landlock programs and if @usage is greater than 1, then the
+ * thread must duplicate &struct landlock_prog_set to not change the
+ * children's programs as well.
+ * @programs: array of non-NULL &struct landlock_prog_list pointers
+ */
+struct landlock_prog_set {
+ struct landlock_prog_list *programs[_LANDLOCK_HOOK_LAST];
+ refcount_t usage;
+};
+
+/**
+ * get_index - get an index for the programs of struct landlock_prog_set
+ *
+ * @type: a Landlock hook type
+ */
+static inline int get_index(enum landlock_hook_type type)
+{
+ /* type ID > 0 for loaded programs */
+ return type - 1;
+}
+
+static inline enum landlock_hook_type get_type(struct bpf_prog *prog)
+{
+ return prog->aux->extra->subtype.landlock_hook.type;
+}
+
#endif /* _SECURITY_LANDLOCK_COMMON_H */
diff --git a/security/landlock/enforce.c b/security/landlock/enforce.c
new file mode 100644
index 000000000000..c06063d9d43d
--- /dev/null
+++ b/security/landlock/enforce.c
@@ -0,0 +1,272 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Landlock LSM - enforcing helpers
+ *
+ * Copyright © 2016-2019 Mickaël Salaün <mic@digikod.net>
+ * Copyright © 2018-2019 ANSSI
+ */
+
+#include <asm/barrier.h> /* smp_store_release() */
+#include <asm/page.h> /* PAGE_SIZE */
+#include <linux/bpf.h> /* bpf_prog_put() */
+#include <linux/compiler.h> /* READ_ONCE() */
+#include <linux/err.h> /* PTR_ERR() */
+#include <linux/errno.h>
+#include <linux/filter.h> /* struct bpf_prog */
+#include <linux/refcount.h>
+#include <linux/slab.h> /* alloc(), kfree() */
+
+#include "common.h" /* struct landlock_prog_list */
+
+/* TODO: use a dedicated kmem_cache_alloc() instead of k*alloc() */
+
+static void put_landlock_prog_list(struct landlock_prog_list *prog_list)
+{
+ struct landlock_prog_list *orig = prog_list;
+
+ /* clean up single-reference branches iteratively */
+ while (orig && refcount_dec_and_test(&orig->usage)) {
+ struct landlock_prog_list *freeme = orig;
+
+ if (orig->prog)
+ bpf_prog_put(orig->prog);
+ orig = orig->prev;
+ kfree(freeme);
+ }
+}
+
+void landlock_put_prog_set(struct landlock_prog_set *prog_set)
+{
+ if (prog_set && refcount_dec_and_test(&prog_set->usage)) {
+ size_t i;
+
+ for (i = 0; i < ARRAY_SIZE(prog_set->programs); i++)
+ put_landlock_prog_list(prog_set->programs[i]);
+ kfree(prog_set);
+ }
+}
+
+void landlock_get_prog_set(struct landlock_prog_set *prog_set)
+{
+ if (!prog_set)
+ return;
+ refcount_inc(&prog_set->usage);
+}
+
+static struct landlock_prog_set *new_landlock_prog_set(void)
+{
+ struct landlock_prog_set *ret;
+
+ /* array filled with NULL values */
+ ret = kzalloc(sizeof(*ret), GFP_KERNEL);
+ if (!ret)
+ return ERR_PTR(-ENOMEM);
+ refcount_set(&ret->usage, 1);
+ return ret;
+}
+
+/**
+ * store_landlock_prog - prepend and deduplicate a Landlock prog_list
+ *
+ * Prepend @prog to @init_prog_set while ignoring @prog
+ * if they are already in @ref_prog_set. Whatever is the result of this
+ * function call, you can call bpf_prog_put(@prog) after.
+ *
+ * @init_prog_set: empty prog_set to prepend to
+ * @ref_prog_set: prog_set to check for duplicate programs
+ * @prog: program to prepend
+ *
+ * Return -errno on error or 0 if @prog was successfully stored.
+ */
+static int store_landlock_prog(struct landlock_prog_set *init_prog_set,
+ const struct landlock_prog_set *ref_prog_set,
+ struct bpf_prog *prog)
+{
+ struct landlock_prog_list *tmp_list = NULL;
+ int err;
+ u32 hook_idx;
+ enum landlock_hook_type last_type;
+ struct bpf_prog *new = prog;
+
+ /* allocate all the memory we need */
+ struct landlock_prog_list *new_list;
+
+ last_type = get_type(new);
+
+ /* ignore duplicate programs */
+ if (ref_prog_set) {
+ struct landlock_prog_list *ref;
+
+ hook_idx = get_index(get_type(new));
+ for (ref = ref_prog_set->programs[hook_idx];
+ ref; ref = ref->prev) {
+ if (ref->prog == new)
+ return -EINVAL;
+ }
+ }
+
+ new = bpf_prog_inc(new);
+ if (IS_ERR(new)) {
+ err = PTR_ERR(new);
+ goto put_tmp_list;
+ }
+ new_list = kzalloc(sizeof(*new_list), GFP_KERNEL);
+ if (!new_list) {
+ bpf_prog_put(new);
+ err = -ENOMEM;
+ goto put_tmp_list;
+ }
+ /* ignore Landlock types in this tmp_list */
+ new_list->prog = new;
+ new_list->prev = tmp_list;
+ refcount_set(&new_list->usage, 1);
+ tmp_list = new_list;
+
+ if (!tmp_list)
+ /* inform user space that this program was already added */
+ return -EEXIST;
+
+ /* properly store the list (without error cases) */
+ while (tmp_list) {
+ struct landlock_prog_list *new_list;
+
+ new_list = tmp_list;
+ tmp_list = tmp_list->prev;
+ /* do not increment the previous prog list usage */
+ hook_idx = get_index(get_type(new_list->prog));
+ new_list->prev = init_prog_set->programs[hook_idx];
+ /* no need to add from the last program to the first because
+ * each of them are a different Landlock type */
+ smp_store_release(&init_prog_set->programs[hook_idx], new_list);
+ }
+ return 0;
+
+put_tmp_list:
+ put_landlock_prog_list(tmp_list);
+ return err;
+}
+
+/* limit Landlock programs set to 256KB */
+#define LANDLOCK_PROGRAMS_MAX_PAGES (1 << 6)
+
+/**
+ * landlock_prepend_prog - attach a Landlock prog_list to @current_prog_set
+ *
+ * Whatever is the result of this function call, you can call
+ * bpf_prog_put(@prog) after.
+ *
+ * @current_prog_set: landlock_prog_set pointer, must be locked (if needed) to
+ * prevent a concurrent put/free. This pointer must not be
+ * freed after the call.
+ * @prog: non-NULL Landlock prog_list to prepend to @current_prog_set. @prog
+ * will be owned by landlock_prepend_prog() and freed if an error
+ * happened.
+ *
+ * Return @current_prog_set or a new pointer when OK. Return a pointer error
+ * otherwise.
+ */
+struct landlock_prog_set *landlock_prepend_prog(
+ struct landlock_prog_set *current_prog_set,
+ struct bpf_prog *prog)
+{
+ struct landlock_prog_set *new_prog_set = current_prog_set;
+ unsigned long pages;
+ int err;
+ size_t i;
+ struct landlock_prog_set tmp_prog_set = {};
+
+ if (prog->type != BPF_PROG_TYPE_LANDLOCK_HOOK)
+ return ERR_PTR(-EINVAL);
+
+ /* validate memory size allocation */
+ pages = prog->pages;
+ if (current_prog_set) {
+ size_t i;
+
+ for (i = 0; i < ARRAY_SIZE(current_prog_set->programs); i++) {
+ struct landlock_prog_list *walker_p;
+
+ for (walker_p = current_prog_set->programs[i];
+ walker_p; walker_p = walker_p->prev)
+ pages += walker_p->prog->pages;
+ }
+ /* count a struct landlock_prog_set if we need to allocate one */
+ if (refcount_read(¤t_prog_set->usage) != 1)
+ pages += round_up(sizeof(*current_prog_set), PAGE_SIZE)
+ / PAGE_SIZE;
+ }
+ if (pages > LANDLOCK_PROGRAMS_MAX_PAGES)
+ return ERR_PTR(-E2BIG);
+
+ /* ensure early that we can allocate enough memory for the new
+ * prog_lists */
+ err = store_landlock_prog(&tmp_prog_set, current_prog_set, prog);
+ if (err)
+ return ERR_PTR(err);
+
+ /*
+ * Each task_struct points to an array of prog list pointers. These
+ * tables are duplicated when additions are made (which means each
+ * table needs to be refcounted for the processes using it). When a new
+ * table is created, all the refcounters on the prog_list are bumped (to
+ * track each table that references the prog). When a new prog is
+ * added, it's just prepended to the list for the new table to point
+ * at.
+ *
+ * Manage all the possible errors before this step to not uselessly
+ * duplicate current_prog_set and avoid a rollback.
+ */
+ if (!new_prog_set) {
+ /*
+ * If there is no Landlock program set used by the current task,
+ * then create a new one.
+ */
+ new_prog_set = new_landlock_prog_set();
+ if (IS_ERR(new_prog_set))
+ goto put_tmp_lists;
+ } else if (refcount_read(¤t_prog_set->usage) > 1) {
+ /*
+ * If the current task is not the sole user of its Landlock
+ * program set, then duplicate them.
+ */
+ new_prog_set = new_landlock_prog_set();
+ if (IS_ERR(new_prog_set))
+ goto put_tmp_lists;
+ for (i = 0; i < ARRAY_SIZE(new_prog_set->programs); i++) {
+ new_prog_set->programs[i] =
+ READ_ONCE(current_prog_set->programs[i]);
+ if (new_prog_set->programs[i])
+ refcount_inc(&new_prog_set->programs[i]->usage);
+ }
+
+ /*
+ * Landlock program set from the current task will not be freed
+ * here because the usage is strictly greater than 1. It is
+ * only prevented to be freed by another task thanks to the
+ * caller of landlock_prepend_prog() which should be locked if
+ * needed.
+ */
+ landlock_put_prog_set(current_prog_set);
+ }
+
+ /* prepend tmp_prog_set to new_prog_set */
+ for (i = 0; i < ARRAY_SIZE(tmp_prog_set.programs); i++) {
+ /* get the last new list */
+ struct landlock_prog_list *last_list =
+ tmp_prog_set.programs[i];
+
+ if (last_list) {
+ while (last_list->prev)
+ last_list = last_list->prev;
+ /* no need to increment usage (pointer replacement) */
+ last_list->prev = new_prog_set->programs[i];
+ new_prog_set->programs[i] = tmp_prog_set.programs[i];
+ }
+ }
+ return new_prog_set;
+
+put_tmp_lists:
+ for (i = 0; i < ARRAY_SIZE(tmp_prog_set.programs); i++)
+ put_landlock_prog_list(tmp_prog_set.programs[i]);
+ return new_prog_set;
+}
diff --git a/security/landlock/enforce.h b/security/landlock/enforce.h
new file mode 100644
index 000000000000..39b800d9999f
--- /dev/null
+++ b/security/landlock/enforce.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Landlock LSM - enforcing helpers headers
+ *
+ * Copyright © 2016-2019 Mickaël Salaün <mic@digikod.net>
+ * Copyright © 2018-2019 ANSSI
+ */
+
+#ifndef _SECURITY_LANDLOCK_ENFORCE_H
+#define _SECURITY_LANDLOCK_ENFORCE_H
+
+struct landlock_prog_set *landlock_prepend_prog(
+ struct landlock_prog_set *current_prog_set,
+ struct bpf_prog *prog);
+void landlock_put_prog_set(struct landlock_prog_set *prog_set);
+void landlock_get_prog_set(struct landlock_prog_set *prog_set);
+
+#endif /* _SECURITY_LANDLOCK_ENFORCE_H */
diff --git a/security/landlock/enforce_seccomp.c b/security/landlock/enforce_seccomp.c
new file mode 100644
index 000000000000..c38c81e6b01a
--- /dev/null
+++ b/security/landlock/enforce_seccomp.c
@@ -0,0 +1,92 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Landlock LSM - enforcing with seccomp
+ *
+ * Copyright © 2016-2018 Mickaël Salaün <mic@digikod.net>
+ * Copyright © 2018-2019 ANSSI
+ */
+
+#ifdef CONFIG_SECCOMP_FILTER
+
+#include <linux/bpf.h> /* bpf_prog_put() */
+#include <linux/capability.h>
+#include <linux/err.h> /* PTR_ERR() */
+#include <linux/errno.h>
+#include <linux/filter.h> /* struct bpf_prog */
+#include <linux/landlock.h>
+#include <linux/refcount.h>
+#include <linux/sched.h> /* current */
+#include <linux/uaccess.h> /* get_user() */
+
+#include "enforce.h"
+
+/* headers in include/linux/landlock.h */
+
+/**
+ * landlock_seccomp_prepend_prog - attach a Landlock program to the current
+ * process
+ *
+ * current->seccomp.landlock_state->prog_set is lazily allocated. When a
+ * process fork, only a pointer is copied. When a new program is added by a
+ * process, if there is other references to this process' prog_set, then a new
+ * allocation is made to contain an array pointing to Landlock program lists.
+ * This design enable low-performance impact and is memory efficient while
+ * keeping the property of prepend-only programs.
+ *
+ * For now, installing a Landlock prog requires that the requesting task has
+ * the global CAP_SYS_ADMIN. We cannot force the use of no_new_privs to not
+ * exclude containers where a process may legitimately acquire more privileges
+ * thanks to an SUID binary.
+ *
+ * @flags: not used for now, but could be used for TSYNC
+ * @user_bpf_fd: file descriptor pointing to a loaded Landlock prog
+ */
+int landlock_seccomp_prepend_prog(unsigned int flags,
+ const int __user *user_bpf_fd)
+{
+ struct landlock_prog_set *new_prog_set;
+ struct bpf_prog *prog;
+ int bpf_fd, err;
+
+ /* planned to be replaced with a no_new_privs check to allow
+ * unprivileged tasks */
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ /* enable to check if Landlock is supported with early EFAULT */
+ if (!user_bpf_fd)
+ return -EFAULT;
+ if (flags)
+ return -EINVAL;
+ err = get_user(bpf_fd, user_bpf_fd);
+ if (err)
+ return err;
+
+ prog = bpf_prog_get(bpf_fd);
+ if (IS_ERR(prog))
+ return PTR_ERR(prog);
+
+ /*
+ * We don't need to lock anything for the current process hierarchy,
+ * everything is guarded by the atomic counters.
+ */
+ new_prog_set = landlock_prepend_prog(
+ current->seccomp.landlock_prog_set, prog);
+ bpf_prog_put(prog);
+ /* @prog is managed/freed by landlock_prepend_prog() */
+ if (IS_ERR(new_prog_set))
+ return PTR_ERR(new_prog_set);
+ current->seccomp.landlock_prog_set = new_prog_set;
+ return 0;
+}
+
+void put_seccomp_landlock(struct task_struct *tsk)
+{
+ landlock_put_prog_set(tsk->seccomp.landlock_prog_set);
+}
+
+void get_seccomp_landlock(struct task_struct *tsk)
+{
+ landlock_get_prog_set(tsk->seccomp.landlock_prog_set);
+}
+
+#endif /* CONFIG_SECCOMP_FILTER */
--
2.20.1
^ permalink raw reply related
* [PATCH bpf-next v9 09/10] bpf,landlock: Add tests for Landlock
From: Mickaël Salaün @ 2019-06-25 21:52 UTC (permalink / raw)
To: linux-kernel
Cc: Mickaël Salaün, Aleksa Sarai, Alexander Viro,
Alexei Starovoitov, Andrew Morton, Andy Lutomirski,
Arnaldo Carvalho de Melo, Casey Schaufler, Daniel Borkmann,
David Drysdale, David S . Miller, Eric W . Biederman,
James Morris, Jann Horn, John Johansen, Jonathan Corbet,
Kees Cook, Michael Kerrisk, Mickaël Salaün, Paul Moore,
Sargun Dhillon, Serge E . Hallyn, Shuah Khan, Stephen Smalley,
Tejun Heo, Tetsuo Handa, Thomas Graf, Tycho Andersen, Will Drewry,
kernel-hardening, linux-api, linux-fsdevel, linux-security-module,
netdev
In-Reply-To: <20190625215239.11136-1-mic@digikod.net>
Test basic context access, ptrace protection and filesystem hooks.
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: James Morris <jmorris@namei.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Serge E. Hallyn <serge@hallyn.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Will Drewry <wad@chromium.org>
---
Changes since v8:
* update eBPF include path for macros
* use TEST_GEN_PROGS and use the generic "clean" target
* add more verbose errors
* update the bpf/verifier files
* remove chain tests (from landlock and bpf/verifier)
* replace the whitelist tests with blacklist tests (because of stateless
Landlock programs): remove "dotdot" tests and other depth tests
* sync the landlock Makefile with its bpf sibling directory and use
bpf_load_program_xattr()
Changes since v7:
* update tests and add new ones for filesystem hierarchy and Landlock
chains.
Changes since v6:
* use the new kselftest_harness.h
* use const variables
* replace ASSERT_STEP with ASSERT_*
* rename BPF_PROG_TYPE_LANDLOCK to BPF_PROG_TYPE_LANDLOCK_RULE
* force sample library rebuild
* fix install target
Changes since v5:
* add subtype test
* add ptrace tests
* split and rename files
* cleanup and rebase
---
tools/testing/selftests/Makefile | 1 +
tools/testing/selftests/bpf/bpf_helpers.h | 2 +
tools/testing/selftests/bpf/test_verifier.c | 1 +
.../testing/selftests/bpf/verifier/landlock.c | 35 +++
.../testing/selftests/bpf/verifier/subtype.c | 10 +
tools/testing/selftests/landlock/.gitignore | 4 +
tools/testing/selftests/landlock/Makefile | 39 +++
tools/testing/selftests/landlock/test.h | 48 ++++
tools/testing/selftests/landlock/test_base.c | 24 ++
tools/testing/selftests/landlock/test_fs.c | 257 ++++++++++++++++++
.../testing/selftests/landlock/test_ptrace.c | 154 +++++++++++
11 files changed, 575 insertions(+)
create mode 100644 tools/testing/selftests/bpf/verifier/landlock.c
create mode 100644 tools/testing/selftests/landlock/.gitignore
create mode 100644 tools/testing/selftests/landlock/Makefile
create mode 100644 tools/testing/selftests/landlock/test.h
create mode 100644 tools/testing/selftests/landlock/test_base.c
create mode 100644 tools/testing/selftests/landlock/test_fs.c
create mode 100644 tools/testing/selftests/landlock/test_ptrace.c
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 9781ca79794a..342a7d714fb9 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -21,6 +21,7 @@ TARGETS += ir
TARGETS += kcmp
TARGETS += kexec
TARGETS += kvm
+TARGETS += landlock
TARGETS += lib
TARGETS += livepatch
TARGETS += membarrier
diff --git a/tools/testing/selftests/bpf/bpf_helpers.h b/tools/testing/selftests/bpf/bpf_helpers.h
index 1a5b1accf091..0b15c49fac3f 100644
--- a/tools/testing/selftests/bpf/bpf_helpers.h
+++ b/tools/testing/selftests/bpf/bpf_helpers.h
@@ -225,6 +225,8 @@ static void *(*bpf_sk_storage_get)(void *map, struct bpf_sock *sk,
static int (*bpf_sk_storage_delete)(void *map, struct bpf_sock *sk) =
(void *)BPF_FUNC_sk_storage_delete;
static int (*bpf_send_signal)(unsigned sig) = (void *)BPF_FUNC_send_signal;
+static unsigned long long (*bpf_inode_map_lookup)(void *map, void *key) =
+ (void *) BPF_FUNC_inode_map_lookup;
/* llvm builtin functions that eBPF C program may use to
* emit BPF_LD_ABS and BPF_LD_IND instructions
diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index 93faffd31fc3..c67218ffebf9 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -30,6 +30,7 @@
#include <linux/bpf.h>
#include <linux/if_ether.h>
#include <linux/btf.h>
+#include <linux/landlock.h>
#include <bpf/bpf.h>
#include <bpf/libbpf.h>
diff --git a/tools/testing/selftests/bpf/verifier/landlock.c b/tools/testing/selftests/bpf/verifier/landlock.c
new file mode 100644
index 000000000000..7ed4e24c0a88
--- /dev/null
+++ b/tools/testing/selftests/bpf/verifier/landlock.c
@@ -0,0 +1,35 @@
+{
+ "landlock/fs_pick: always accept",
+ .insns = {
+ BPF_MOV32_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .result = ACCEPT,
+ .prog_type = BPF_PROG_TYPE_LANDLOCK_HOOK,
+ .has_prog_subtype = true,
+ .prog_subtype = {
+ .landlock_hook = {
+ .type = LANDLOCK_HOOK_FS_PICK,
+ .triggers = LANDLOCK_TRIGGER_FS_PICK_READ,
+ }
+ },
+},
+{
+ "landlock/fs_pick: read context",
+ .insns = {
+ BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
+ BPF_LDX_MEM(BPF_DW, BPF_REG_7, BPF_REG_6,
+ offsetof(struct landlock_ctx_fs_pick, inode)),
+ BPF_MOV32_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .result = ACCEPT,
+ .prog_type = BPF_PROG_TYPE_LANDLOCK_HOOK,
+ .has_prog_subtype = true,
+ .prog_subtype = {
+ .landlock_hook = {
+ .type = LANDLOCK_HOOK_FS_PICK,
+ .triggers = LANDLOCK_TRIGGER_FS_PICK_READ,
+ }
+ },
+},
diff --git a/tools/testing/selftests/bpf/verifier/subtype.c b/tools/testing/selftests/bpf/verifier/subtype.c
index cf614223d53f..6bb7ef4b39b5 100644
--- a/tools/testing/selftests/bpf/verifier/subtype.c
+++ b/tools/testing/selftests/bpf/verifier/subtype.c
@@ -8,3 +8,13 @@
.result = REJECT,
.has_prog_subtype = true,
},
+{
+ "missing subtype",
+ .insns = {
+ BPF_MOV32_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .errstr = "",
+ .result = REJECT,
+ .prog_type = BPF_PROG_TYPE_LANDLOCK_HOOK,
+},
diff --git a/tools/testing/selftests/landlock/.gitignore b/tools/testing/selftests/landlock/.gitignore
new file mode 100644
index 000000000000..25b9cd834c3c
--- /dev/null
+++ b/tools/testing/selftests/landlock/.gitignore
@@ -0,0 +1,4 @@
+/test_base
+/test_fs
+/test_ptrace
+/tmp_*
diff --git a/tools/testing/selftests/landlock/Makefile b/tools/testing/selftests/landlock/Makefile
new file mode 100644
index 000000000000..7a253bf6d580
--- /dev/null
+++ b/tools/testing/selftests/landlock/Makefile
@@ -0,0 +1,39 @@
+LIBDIR := ../../../lib
+BPFDIR := $(LIBDIR)/bpf
+APIDIR := ../../../include/uapi
+GENDIR := ../../../../include/generated
+GENHDR := $(GENDIR)/autoconf.h
+
+ifneq ($(wildcard $(GENHDR)),)
+ GENFLAGS := -DHAVE_GENHDR
+endif
+
+BPFOBJS := $(BPFDIR)/bpf.o $(BPFDIR)/nlattr.o
+LOADOBJ := ../../../../samples/bpf/bpf_load.o
+
+CFLAGS += -Wl,-no-as-needed -Wall -O2 -I$(APIDIR) -I$(LIBDIR) -I$(BPFDIR) -I$(GENDIR) $(GENFLAGS) -I../../../include
+LDFLAGS += -lelf
+
+test_src = $(wildcard test_*.c)
+
+test_objs := $(test_src:.c=)
+
+TEST_GEN_PROGS := $(test_objs)
+
+.PHONY: all clean force
+
+all: $(test_objs)
+
+# force a rebuild of BPFOBJS when its dependencies are updated
+force:
+
+# rebuild bpf.o as a workaround for the samples/bpf bug
+$(BPFOBJS): $(LOADOBJ) force
+ $(MAKE) -C $(BPFDIR)
+
+$(LOADOBJ): force
+ $(MAKE) -C $(dir $(LOADOBJ))
+
+$(test_objs): $(BPFOBJS) $(LOADOBJ) ../kselftest_harness.h
+
+include ../lib.mk
diff --git a/tools/testing/selftests/landlock/test.h b/tools/testing/selftests/landlock/test.h
new file mode 100644
index 000000000000..7d412d94148c
--- /dev/null
+++ b/tools/testing/selftests/landlock/test.h
@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Landlock helpers
+ *
+ * Copyright © 2017-2019 Mickaël Salaün <mic@digikod.net>
+ * Copyright © 2019 ANSSI
+ */
+
+#include <bpf/bpf.h>
+#include <errno.h>
+#include <linux/filter.h>
+#include <linux/landlock.h>
+#include <linux/seccomp.h>
+#include <sys/prctl.h>
+#include <sys/syscall.h>
+
+#include "../kselftest_harness.h"
+#include "../../../../samples/bpf/bpf_load.h"
+
+#ifndef SECCOMP_PREPEND_LANDLOCK_PROG
+#define SECCOMP_PREPEND_LANDLOCK_PROG 4
+#endif
+
+#ifndef seccomp
+static int __attribute__((unused)) seccomp(unsigned int op, unsigned int flags,
+ void *args)
+{
+ errno = 0;
+ return syscall(__NR_seccomp, op, flags, args);
+}
+#endif
+
+/* bpf_load_program() with subtype */
+static int __attribute__((unused)) ll_bpf_load_program(
+ const struct bpf_insn *insns, size_t insns_cnt, char *log_buf,
+ size_t log_buf_sz, const union bpf_prog_subtype *subtype)
+{
+ struct bpf_load_program_attr load_attr;
+
+ memset(&load_attr, 0, sizeof(struct bpf_load_program_attr));
+ load_attr.prog_type = BPF_PROG_TYPE_LANDLOCK_HOOK;
+ load_attr.prog_subtype = subtype;
+ load_attr.insns = insns;
+ load_attr.insns_cnt = insns_cnt;
+ load_attr.license = "GPL";
+
+ return bpf_load_program_xattr(&load_attr, log_buf, log_buf_sz);
+}
diff --git a/tools/testing/selftests/landlock/test_base.c b/tools/testing/selftests/landlock/test_base.c
new file mode 100644
index 000000000000..db46f39048cb
--- /dev/null
+++ b/tools/testing/selftests/landlock/test_base.c
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Landlock tests - base
+ *
+ * Copyright © 2017-2019 Mickaël Salaün <mic@digikod.net>
+ */
+
+#define _GNU_SOURCE
+#include <errno.h>
+
+#include "test.h"
+
+TEST(seccomp_landlock)
+{
+ int ret;
+
+ ret = seccomp(SECCOMP_PREPEND_LANDLOCK_PROG, 0, NULL);
+ EXPECT_EQ(-1, ret);
+ EXPECT_EQ(EFAULT, errno) {
+ TH_LOG("Kernel does not support CONFIG_SECURITY_LANDLOCK");
+ }
+}
+
+TEST_HARNESS_MAIN
diff --git a/tools/testing/selftests/landlock/test_fs.c b/tools/testing/selftests/landlock/test_fs.c
new file mode 100644
index 000000000000..dba726ea4994
--- /dev/null
+++ b/tools/testing/selftests/landlock/test_fs.c
@@ -0,0 +1,257 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Landlock tests - file system
+ *
+ * Copyright © 2018-2019 Mickaël Salaün <mic@digikod.net>
+ */
+
+#include <fcntl.h> /* O_DIRECTORY */
+#include <sys/stat.h> /* statbuf */
+#include <unistd.h> /* faccessat() */
+
+#include "test.h"
+
+#define TEST_PATH_TRIGGERS ( \
+ LANDLOCK_TRIGGER_FS_PICK_OPEN | \
+ LANDLOCK_TRIGGER_FS_PICK_READDIR | \
+ LANDLOCK_TRIGGER_FS_PICK_EXECUTE | \
+ LANDLOCK_TRIGGER_FS_PICK_GETATTR)
+
+static void test_path_rel(struct __test_metadata *_metadata, int dirfd,
+ const char *path, int ret)
+{
+ int fd;
+ struct stat statbuf;
+
+ ASSERT_EQ(ret, faccessat(dirfd, path, R_OK | X_OK, 0));
+ ASSERT_EQ(ret, fstatat(dirfd, path, &statbuf, 0));
+ fd = openat(dirfd, path, O_DIRECTORY);
+ if (ret) {
+ ASSERT_EQ(-1, fd);
+ } else {
+ ASSERT_NE(-1, fd);
+ EXPECT_EQ(0, close(fd));
+ }
+}
+
+static void test_path(struct __test_metadata *_metadata, const char *path,
+ int ret)
+{
+ return test_path_rel(_metadata, AT_FDCWD, path, ret);
+}
+
+static const char d1[] = "/usr";
+static const char d2[] = "/usr/share";
+static const char d3[] = "/usr/share/doc";
+
+TEST(fs_base)
+{
+ test_path(_metadata, d1, 0);
+ test_path(_metadata, d2, 0);
+ test_path(_metadata, d3, 0);
+}
+
+#define MAP_VALUE_DENY 1
+
+static int create_denied_inode_map(struct __test_metadata *_metadata,
+ const char *const dirs[])
+{
+ int map, key, dirs_len, i;
+ __u64 value = MAP_VALUE_DENY;
+
+ ASSERT_NE(NULL, dirs) {
+ TH_LOG("No directory list\n");
+ }
+ ASSERT_NE(NULL, dirs[0]) {
+ TH_LOG("Empty directory list\n");
+ }
+
+ /* get the number of dir entries */
+ for (dirs_len = 0; dirs[dirs_len]; dirs_len++);
+ map = bpf_create_map(BPF_MAP_TYPE_INODE, sizeof(key), sizeof(value),
+ dirs_len, 0);
+ ASSERT_NE(-1, map) {
+ TH_LOG("Failed to create a map of %d elements: %s\n", dirs_len,
+ strerror(errno));
+ }
+
+ for (i = 0; dirs[i]; i++) {
+ key = open(dirs[i], O_RDONLY | O_CLOEXEC | O_DIRECTORY);
+ ASSERT_NE(-1, key) {
+ TH_LOG("Failed to open directory \"%s\": %s\n", dirs[i],
+ strerror(errno));
+ }
+ ASSERT_EQ(0, bpf_map_update_elem(map, &key, &value, BPF_ANY)) {
+ TH_LOG("Failed to update the map with \"%s\": %s\n",
+ dirs[i], strerror(errno));
+ }
+ close(key);
+ }
+ return map;
+}
+
+static void enforce_map(struct __test_metadata *_metadata, int map,
+ bool subpath)
+{
+ const struct bpf_insn prog_deny[] = {
+ BPF_ALU64_REG(BPF_MOV, BPF_REG_6, BPF_REG_1),
+ /* look for the requested inode in the map */
+ BPF_LDX_MEM(BPF_DW, BPF_REG_2, BPF_REG_6,
+ offsetof(struct landlock_ctx_fs_walk, inode)),
+ BPF_LD_MAP_FD(BPF_REG_1, map), /* 2 instructions */
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
+ BPF_FUNC_inode_map_lookup),
+ /* if it is there, then deny access to the inode, otherwise
+ * allow it */
+ BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, MAP_VALUE_DENY, 2),
+ BPF_MOV32_IMM(BPF_REG_0, LANDLOCK_RET_ALLOW),
+ BPF_EXIT_INSN(),
+ BPF_MOV32_IMM(BPF_REG_0, LANDLOCK_RET_DENY),
+ BPF_EXIT_INSN(),
+ };
+ union bpf_prog_subtype subtype = {};
+ int fd_walk = -1, fd_pick;
+ char log[1024] = "";
+
+ if (subpath) {
+ subtype.landlock_hook.type = LANDLOCK_HOOK_FS_WALK;
+ fd_walk = ll_bpf_load_program((const struct bpf_insn *)&prog_deny,
+ sizeof(prog_deny) / sizeof(struct bpf_insn),
+ log, sizeof(log), &subtype);
+ ASSERT_NE(-1, fd_walk) {
+ TH_LOG("Failed to load fs_walk program: %s\n%s",
+ strerror(errno), log);
+ }
+ ASSERT_EQ(0, seccomp(SECCOMP_PREPEND_LANDLOCK_PROG, 0, &fd_walk)) {
+ TH_LOG("Failed to apply Landlock program: %s", strerror(errno));
+ }
+ EXPECT_EQ(0, close(fd_walk));
+ }
+
+ subtype.landlock_hook.type = LANDLOCK_HOOK_FS_PICK;
+ subtype.landlock_hook.triggers = TEST_PATH_TRIGGERS;
+ fd_pick = ll_bpf_load_program((const struct bpf_insn *)&prog_deny,
+ sizeof(prog_deny) / sizeof(struct bpf_insn), log,
+ sizeof(log), &subtype);
+ ASSERT_NE(-1, fd_pick) {
+ TH_LOG("Failed to load fs_pick program: %s\n%s",
+ strerror(errno), log);
+ }
+ ASSERT_EQ(0, seccomp(SECCOMP_PREPEND_LANDLOCK_PROG, 0, &fd_pick)) {
+ TH_LOG("Failed to apply Landlock program: %s", strerror(errno));
+ }
+ EXPECT_EQ(0, close(fd_pick));
+}
+
+static void check_map_blacklist(struct __test_metadata *_metadata,
+ bool subpath)
+{
+ int map = create_denied_inode_map(_metadata, (const char *const [])
+ { d2, NULL });
+ ASSERT_NE(-1, map);
+ enforce_map(_metadata, map, subpath);
+ test_path(_metadata, d1, 0);
+ test_path(_metadata, d2, -1);
+ test_path(_metadata, d3, subpath ? -1 : 0);
+ EXPECT_EQ(0, close(map));
+}
+
+TEST(fs_map_blacklist_literal)
+{
+ check_map_blacklist(_metadata, false);
+}
+
+TEST(fs_map_blacklist_subpath)
+{
+ check_map_blacklist(_metadata, true);
+}
+
+static const char r2[] = ".";
+static const char r3[] = "./doc";
+
+enum relative_access {
+ REL_OPEN,
+ REL_CHDIR,
+ REL_CHROOT,
+};
+
+static void check_access(struct __test_metadata *_metadata,
+ bool enforce, enum relative_access rel)
+{
+ int dirfd;
+ int map = -1;
+
+ if (rel == REL_CHROOT)
+ ASSERT_NE(-1, chdir(d2));
+ if (enforce) {
+ map = create_denied_inode_map(_metadata, (const char *const [])
+ { d3, NULL });
+ ASSERT_NE(-1, map);
+ enforce_map(_metadata, map, true);
+ }
+ switch (rel) {
+ case REL_OPEN:
+ dirfd = open(d2, O_DIRECTORY);
+ ASSERT_NE(-1, dirfd);
+ break;
+ case REL_CHDIR:
+ ASSERT_NE(-1, chdir(d2));
+ dirfd = AT_FDCWD;
+ break;
+ case REL_CHROOT:
+ ASSERT_NE(-1, chroot(d2)) {
+ TH_LOG("Failed to chroot: %s\n", strerror(errno));
+ }
+ dirfd = AT_FDCWD;
+ break;
+ default:
+ ASSERT_TRUE(false);
+ return;
+ }
+
+ test_path_rel(_metadata, dirfd, r2, 0);
+ test_path_rel(_metadata, dirfd, r3, enforce ? -1 : 0);
+
+ if (rel == REL_OPEN)
+ EXPECT_EQ(0, close(dirfd));
+ if (enforce)
+ EXPECT_EQ(0, close(map));
+}
+
+TEST(fs_allow_open)
+{
+ /* no enforcement, via open */
+ check_access(_metadata, false, REL_OPEN);
+}
+
+TEST(fs_allow_chdir)
+{
+ /* no enforcement, via chdir */
+ check_access(_metadata, false, REL_CHDIR);
+}
+
+TEST(fs_allow_chroot)
+{
+ /* no enforcement, via chroot */
+ check_access(_metadata, false, REL_CHROOT);
+}
+
+TEST(fs_deny_open)
+{
+ /* enforcement without tag, via open */
+ check_access(_metadata, true, REL_OPEN);
+}
+
+TEST(fs_deny_chdir)
+{
+ /* enforcement without tag, via chdir */
+ check_access(_metadata, true, REL_CHDIR);
+}
+
+TEST(fs_deny_chroot)
+{
+ /* enforcement without tag, via chroot */
+ check_access(_metadata, true, REL_CHROOT);
+}
+
+TEST_HARNESS_MAIN
diff --git a/tools/testing/selftests/landlock/test_ptrace.c b/tools/testing/selftests/landlock/test_ptrace.c
new file mode 100644
index 000000000000..2f3e346288bc
--- /dev/null
+++ b/tools/testing/selftests/landlock/test_ptrace.c
@@ -0,0 +1,154 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Landlock tests - ptrace
+ *
+ * Copyright © 2017-2019 Mickaël Salaün <mic@digikod.net>
+ */
+
+#define _GNU_SOURCE
+#include <signal.h> /* raise */
+#include <sys/ptrace.h>
+#include <sys/types.h> /* waitpid */
+#include <sys/wait.h> /* waitpid */
+#include <unistd.h> /* fork, pipe */
+
+#include "test.h"
+
+static void apply_null_sandbox(struct __test_metadata *_metadata)
+{
+ const struct bpf_insn prog_accept[] = {
+ BPF_MOV32_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ };
+ const union bpf_prog_subtype subtype = {
+ .landlock_hook = {
+ .type = LANDLOCK_HOOK_FS_PICK,
+ .triggers = LANDLOCK_TRIGGER_FS_PICK_OPEN,
+ }
+ };
+ int prog;
+ char log[256] = "";
+
+ prog = ll_bpf_load_program((const struct bpf_insn *)&prog_accept,
+ sizeof(prog_accept) / sizeof(struct bpf_insn), log,
+ sizeof(log), &subtype);
+ ASSERT_NE(-1, prog) {
+ TH_LOG("Failed to load minimal rule: %s\n%s",
+ strerror(errno), log);
+ }
+ ASSERT_EQ(0, seccomp(SECCOMP_PREPEND_LANDLOCK_PROG, 0, &prog)) {
+ TH_LOG("Failed to apply minimal rule: %s", strerror(errno));
+ }
+ EXPECT_EQ(0, close(prog));
+}
+
+/* PTRACE_TRACEME and PTRACE_ATTACH without Landlock rules effect */
+static void check_ptrace(struct __test_metadata *_metadata,
+ int sandbox_both, int sandbox_parent, int sandbox_child,
+ int expect_ptrace)
+{
+ pid_t child;
+ int status;
+ int pipefd[2];
+
+ ASSERT_EQ(0, pipe(pipefd));
+ if (sandbox_both)
+ apply_null_sandbox(_metadata);
+
+ child = fork();
+ ASSERT_LE(0, child);
+ if (child == 0) {
+ char buf;
+
+ EXPECT_EQ(0, close(pipefd[1]));
+ if (sandbox_child)
+ apply_null_sandbox(_metadata);
+
+ /* test traceme */
+ ASSERT_EQ(expect_ptrace, ptrace(PTRACE_TRACEME));
+ if (expect_ptrace) {
+ ASSERT_EQ(EPERM, errno);
+ } else {
+ ASSERT_EQ(0, raise(SIGSTOP));
+ }
+
+ /* sync */
+ ASSERT_EQ(1, read(pipefd[0], &buf, 1)) {
+ TH_LOG("Failed to read() sync from parent");
+ }
+ ASSERT_EQ('.', buf);
+ _exit(_metadata->passed ? EXIT_SUCCESS : EXIT_FAILURE);
+ }
+
+ EXPECT_EQ(0, close(pipefd[0]));
+ if (sandbox_parent)
+ apply_null_sandbox(_metadata);
+
+ /* test traceme */
+ if (!expect_ptrace) {
+ ASSERT_EQ(child, waitpid(child, &status, 0));
+ ASSERT_EQ(1, WIFSTOPPED(status));
+ ASSERT_EQ(0, ptrace(PTRACE_DETACH, child, NULL, 0));
+ }
+ /* test attach */
+ ASSERT_EQ(expect_ptrace, ptrace(PTRACE_ATTACH, child, NULL, 0));
+ if (expect_ptrace) {
+ ASSERT_EQ(EPERM, errno);
+ } else {
+ ASSERT_EQ(child, waitpid(child, &status, 0));
+ ASSERT_EQ(1, WIFSTOPPED(status));
+ ASSERT_EQ(0, ptrace(PTRACE_CONT, child, NULL, 0));
+ }
+
+ /* sync */
+ ASSERT_EQ(1, write(pipefd[1], ".", 1)) {
+ TH_LOG("Failed to write() sync to child");
+ }
+ ASSERT_EQ(child, waitpid(child, &status, 0));
+ if (WIFSIGNALED(status) || WEXITSTATUS(status))
+ _metadata->passed = 0;
+}
+
+TEST(ptrace_allow_without_sandbox)
+{
+ /* no sandbox */
+ check_ptrace(_metadata, 0, 0, 0, 0);
+}
+
+TEST(ptrace_allow_with_one_sandbox)
+{
+ /* child sandbox */
+ check_ptrace(_metadata, 0, 0, 1, 0);
+}
+
+TEST(ptrace_allow_with_nested_sandbox)
+{
+ /* inherited and child sandbox */
+ check_ptrace(_metadata, 1, 0, 1, 0);
+}
+
+TEST(ptrace_deny_with_parent_sandbox)
+{
+ /* parent sandbox */
+ check_ptrace(_metadata, 0, 1, 0, -1);
+}
+
+TEST(ptrace_deny_with_nested_and_parent_sandbox)
+{
+ /* inherited and parent sandbox */
+ check_ptrace(_metadata, 1, 1, 0, -1);
+}
+
+TEST(ptrace_deny_with_forked_sandbox)
+{
+ /* inherited, parent and child sandbox */
+ check_ptrace(_metadata, 1, 1, 1, -1);
+}
+
+TEST(ptrace_deny_with_sibling_sandbox)
+{
+ /* parent and child sandbox */
+ check_ptrace(_metadata, 0, 1, 1, -1);
+}
+
+TEST_HARNESS_MAIN
--
2.20.1
^ permalink raw reply related
* [PATCH bpf-next v9 06/10] landlock: Handle filesystem access control
From: Mickaël Salaün @ 2019-06-25 21:52 UTC (permalink / raw)
To: linux-kernel
Cc: Mickaël Salaün, Aleksa Sarai, Alexander Viro,
Alexei Starovoitov, Andrew Morton, Andy Lutomirski,
Arnaldo Carvalho de Melo, Casey Schaufler, Daniel Borkmann,
David Drysdale, David S . Miller, Eric W . Biederman,
James Morris, Jann Horn, John Johansen, Jonathan Corbet,
Kees Cook, Michael Kerrisk, Mickaël Salaün, Paul Moore,
Sargun Dhillon, Serge E . Hallyn, Shuah Khan, Stephen Smalley,
Tejun Heo, Tetsuo Handa, Thomas Graf, Tycho Andersen, Will Drewry,
kernel-hardening, linux-api, linux-fsdevel, linux-security-module,
netdev
In-Reply-To: <20190625215239.11136-1-mic@digikod.net>
This add two Landlock hooks: FS_WALK and FS_PICK.
The FS_WALK hook is used to walk through a file path. A program tied to
this hook will be evaluated for each directory traversal except the last
one if it is the leaf of the path. It is important to differentiate
this hook from FS_PICK to enable more powerful path evaluation in the
future (cf. Landlock patch v8).
The FS_PICK hook is used to validate a set of actions requested on a
file. This actions are defined with triggers (e.g. read, write, open,
append...).
The Landlock LSM hook registration is done after other LSM to only run
actions from user-space, via eBPF programs, if the access was granted by
major (privileged) LSMs.
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: James Morris <jmorris@namei.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Serge E. Hallyn <serge@hallyn.com>
---
Changes since v8:
* add a new LSM_ORDER_LAST, cf. commit e2bc445b66ca ("LSM: Introduce
enum lsm_order")
* add WARN_ON() for pointer dereferencement
* remove the FS_GET subtype which rely on program chaining
* remove the subtype option which was only used for chaining (with the
"previous" field)
* remove inode_lookup which depends on the (removed) nameidata security
blob
* remove eBPF helpers to get and set Landlock inode tags
* do not use task LSM credentials (for now)
Changes since v7:
* major rewrite with clean Landlock hooks able to deal with file paths
Changes since v6:
* add 3 more sub-events: IOCTL, LOCK, FCNTL
https://lkml.kernel.org/r/2fbc99a6-f190-f335-bd14-04bdeed35571@digikod.net
* use the new security_add_hooks()
* explain the -Werror=unused-function
* constify pointers
* cleanup headers
Changes since v5:
* split hooks.[ch] into hooks.[ch] and hooks_fs.[ch]
* add more documentation
* cosmetic fixes
* rebase (SCALAR_VALUE)
Changes since v4:
* add LSM hook abstraction called Landlock event
* use the compiler type checking to verify hooks use by an event
* handle all filesystem related LSM hooks (e.g. file_permission,
mmap_file, sb_mount...)
* register BPF programs for Landlock just after LSM hooks registration
* move hooks registration after other LSMs
* add failsafes to check if a hook is not used by the kernel
* allow partial raw value access form the context (needed for programs
generated by LLVM)
Changes since v3:
* split commit
* add hooks dealing with struct inode and struct path pointers:
inode_permission and inode_getattr
* add abstraction over eBPF helper arguments thanks to wrapping structs
---
include/linux/lsm_hooks.h | 1 +
security/landlock/Makefile | 3 +-
security/landlock/common.h | 10 +
security/landlock/hooks.c | 95 ++++++
security/landlock/hooks.h | 31 ++
security/landlock/hooks_fs.c | 568 +++++++++++++++++++++++++++++++++++
security/landlock/hooks_fs.h | 31 ++
security/landlock/init.c | 47 +++
security/security.c | 15 +
9 files changed, 800 insertions(+), 1 deletion(-)
create mode 100644 security/landlock/hooks.c
create mode 100644 security/landlock/hooks.h
create mode 100644 security/landlock/hooks_fs.c
create mode 100644 security/landlock/hooks_fs.h
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 47f58cfb6a19..eefe9f214f05 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -2092,6 +2092,7 @@ extern void security_add_hooks(struct security_hook_list *hooks, int count,
enum lsm_order {
LSM_ORDER_FIRST = -1, /* This is only for capabilities. */
LSM_ORDER_MUTABLE = 0,
+ LSM_ORDER_LAST = 1, /* potentially-unprivileged LSM */
};
struct lsm_info {
diff --git a/security/landlock/Makefile b/security/landlock/Makefile
index 2a1a7082a365..270ece5d93de 100644
--- a/security/landlock/Makefile
+++ b/security/landlock/Makefile
@@ -1,4 +1,5 @@
obj-$(CONFIG_SECURITY_LANDLOCK) := landlock.o
landlock-y := init.o \
- enforce.o enforce_seccomp.o
+ enforce.o enforce_seccomp.o \
+ hooks.o hooks_fs.o
diff --git a/security/landlock/common.h b/security/landlock/common.h
index 0c9b5904e7f5..49b892515144 100644
--- a/security/landlock/common.h
+++ b/security/landlock/common.h
@@ -11,6 +11,7 @@
#include <linux/bpf.h> /* enum bpf_prog_aux */
#include <linux/filter.h> /* bpf_prog */
+#include <linux/lsm_hooks.h> /* lsm_blob_sizes */
#include <linux/refcount.h> /* refcount_t */
#include <uapi/linux/landlock.h> /* enum landlock_hook_type */
@@ -68,4 +69,13 @@ static inline enum landlock_hook_type get_type(struct bpf_prog *prog)
return prog->aux->extra->subtype.landlock_hook.type;
}
+__maybe_unused
+static bool current_has_prog_type(enum landlock_hook_type hook_type)
+{
+ struct landlock_prog_set *prog_set;
+
+ prog_set = current->seccomp.landlock_prog_set;
+ return (prog_set && prog_set->programs[get_index(hook_type)]);
+}
+
#endif /* _SECURITY_LANDLOCK_COMMON_H */
diff --git a/security/landlock/hooks.c b/security/landlock/hooks.c
new file mode 100644
index 000000000000..a1620d0481eb
--- /dev/null
+++ b/security/landlock/hooks.c
@@ -0,0 +1,95 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Landlock LSM - hook helpers
+ *
+ * Copyright © 2016-2019 Mickaël Salaün <mic@digikod.net>
+ * Copyright © 2018-2019 ANSSI
+ */
+
+#include <asm/current.h>
+#include <linux/bpf.h> /* enum bpf_prog_aux */
+#include <linux/errno.h>
+#include <linux/filter.h> /* BPF_PROG_RUN() */
+#include <linux/rculist.h> /* list_add_tail_rcu */
+#include <uapi/linux/landlock.h> /* struct landlock_context */
+
+#include "common.h" /* struct landlock_rule, get_index() */
+#include "hooks.h" /* landlock_hook_ctx */
+
+#include "hooks_fs.h"
+
+/* return a Landlock program context (e.g. hook_ctx->fs_walk.prog_ctx) */
+static const void *get_ctx(enum landlock_hook_type hook_type,
+ struct landlock_hook_ctx *hook_ctx)
+{
+ switch (hook_type) {
+ case LANDLOCK_HOOK_FS_WALK:
+ return landlock_get_ctx_fs_walk(hook_ctx->fs_walk);
+ case LANDLOCK_HOOK_FS_PICK:
+ return landlock_get_ctx_fs_pick(hook_ctx->fs_pick);
+ }
+ WARN_ON(1);
+ return NULL;
+}
+
+/**
+ * landlock_access_deny - run Landlock programs tied to a hook
+ *
+ * @hook_idx: hook index in the programs array
+ * @ctx: non-NULL valid eBPF context
+ * @prog_set: Landlock program set pointer
+ * @triggers: a bitmask to check if a program should be run
+ *
+ * Return true if at least one program return deny.
+ */
+static bool landlock_access_deny(enum landlock_hook_type hook_type,
+ struct landlock_hook_ctx *hook_ctx,
+ struct landlock_prog_set *prog_set, u64 triggers)
+{
+ struct landlock_prog_list *prog_list, *prev_list = NULL;
+ u32 hook_idx = get_index(hook_type);
+
+ if (!prog_set)
+ return false;
+
+ for (prog_list = prog_set->programs[hook_idx];
+ prog_list; prog_list = prog_list->prev) {
+ u32 ret;
+ const void *prog_ctx;
+
+ /* check if @prog expect at least one of this triggers */
+ if (triggers && !(triggers & prog_list->prog->aux->extra->
+ subtype.landlock_hook.triggers))
+ continue;
+ prog_ctx = get_ctx(hook_type, hook_ctx);
+ if (!prog_ctx || WARN_ON(IS_ERR(prog_ctx)))
+ return true;
+ rcu_read_lock();
+ ret = BPF_PROG_RUN(prog_list->prog, prog_ctx);
+ rcu_read_unlock();
+ /* deny access if a program returns a value different than 0 */
+ if (ret)
+ return true;
+ if (prev_list && prog_list->prev && prog_list->prev->prog->
+ aux->extra->subtype.landlock_hook.type ==
+ prev_list->prog->aux->extra->
+ subtype.landlock_hook.type)
+ WARN_ON(prog_list->prev != prev_list);
+ prev_list = prog_list;
+ }
+ return false;
+}
+
+int landlock_decide(enum landlock_hook_type hook_type,
+ struct landlock_hook_ctx *hook_ctx, u64 triggers)
+{
+ bool deny = false;
+
+#ifdef CONFIG_SECCOMP_FILTER
+ deny = landlock_access_deny(hook_type, hook_ctx,
+ current->seccomp.landlock_prog_set, triggers);
+#endif /* CONFIG_SECCOMP_FILTER */
+
+ /* should we use -EPERM or -EACCES? */
+ return deny ? -EACCES : 0;
+}
diff --git a/security/landlock/hooks.h b/security/landlock/hooks.h
new file mode 100644
index 000000000000..31446e6629fb
--- /dev/null
+++ b/security/landlock/hooks.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Landlock LSM - hooks helpers
+ *
+ * Copyright © 2016-2019 Mickaël Salaün <mic@digikod.net>
+ * Copyright © 2018-2019 ANSSI
+ */
+
+#include <asm/current.h>
+#include <linux/sched.h> /* struct task_struct */
+#include <linux/seccomp.h>
+
+#include "hooks_fs.h"
+
+struct landlock_hook_ctx {
+ union {
+ struct landlock_hook_ctx_fs_walk *fs_walk;
+ struct landlock_hook_ctx_fs_pick *fs_pick;
+ };
+};
+
+static inline bool landlocked(const struct task_struct *task)
+{
+#ifdef CONFIG_SECCOMP_FILTER
+ return !!(task->seccomp.landlock_prog_set);
+#else
+ return false;
+#endif /* CONFIG_SECCOMP_FILTER */
+}
+
+int landlock_decide(enum landlock_hook_type, struct landlock_hook_ctx *, u64);
diff --git a/security/landlock/hooks_fs.c b/security/landlock/hooks_fs.c
new file mode 100644
index 000000000000..c3f0f60d72a7
--- /dev/null
+++ b/security/landlock/hooks_fs.c
@@ -0,0 +1,568 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Landlock LSM - filesystem hooks
+ *
+ * Copyright © 2016-2019 Mickaël Salaün <mic@digikod.net>
+ * Copyright © 2018-2019 ANSSI
+ */
+
+#include <linux/bpf.h> /* enum bpf_access_type */
+#include <linux/kernel.h> /* ARRAY_SIZE */
+#include <linux/lsm_hooks.h>
+#include <linux/rcupdate.h> /* synchronize_rcu() */
+#include <linux/stat.h> /* S_ISDIR */
+#include <linux/stddef.h> /* offsetof */
+#include <linux/types.h> /* uintptr_t */
+#include <linux/workqueue.h> /* INIT_WORK() */
+
+/* permissions translation */
+#include <linux/fs.h> /* MAY_* */
+#include <linux/mman.h> /* PROT_* */
+#include <linux/namei.h>
+
+/* hook arguments */
+#include <linux/dcache.h> /* struct dentry */
+#include <linux/fs.h> /* struct inode, struct iattr */
+#include <linux/mm_types.h> /* struct vm_area_struct */
+#include <linux/mount.h> /* struct vfsmount */
+#include <linux/path.h> /* struct path */
+#include <linux/sched.h> /* struct task_struct */
+#include <linux/time.h> /* struct timespec */
+
+#include "common.h"
+#include "hooks_fs.h"
+#include "hooks.h"
+
+/* fs_pick */
+
+#include <asm/page.h> /* PAGE_SIZE */
+#include <asm/syscall.h>
+#include <linux/dcache.h> /* d_path, dentry_path_raw */
+#include <linux/err.h> /* *_ERR */
+#include <linux/gfp.h> /* __get_free_page, GFP_KERNEL */
+#include <linux/path.h> /* struct path */
+
+bool landlock_is_valid_access_fs_pick(int off, enum bpf_access_type type,
+ enum bpf_reg_type *reg_type, int *max_size)
+{
+ switch (off) {
+ case offsetof(struct landlock_ctx_fs_pick, inode):
+ if (type != BPF_READ)
+ return false;
+ *reg_type = PTR_TO_INODE;
+ *max_size = sizeof(u64);
+ return true;
+ default:
+ return false;
+ }
+}
+
+bool landlock_is_valid_access_fs_walk(int off, enum bpf_access_type type,
+ enum bpf_reg_type *reg_type, int *max_size)
+{
+ switch (off) {
+ case offsetof(struct landlock_ctx_fs_walk, inode):
+ if (type != BPF_READ)
+ return false;
+ *reg_type = PTR_TO_INODE;
+ *max_size = sizeof(u64);
+ return true;
+ default:
+ return false;
+ }
+}
+
+/* fs_walk */
+
+struct landlock_hook_ctx_fs_walk {
+ struct landlock_ctx_fs_walk prog_ctx;
+};
+
+const struct landlock_ctx_fs_walk *landlock_get_ctx_fs_walk(
+ const struct landlock_hook_ctx_fs_walk *hook_ctx)
+{
+ if (WARN_ON(!hook_ctx))
+ return NULL;
+
+ return &hook_ctx->prog_ctx;
+}
+
+static int decide_fs_walk(int may_mask, struct inode *inode)
+{
+ struct landlock_hook_ctx_fs_walk fs_walk = {};
+ struct landlock_hook_ctx hook_ctx = {
+ .fs_walk = &fs_walk,
+ };
+ const enum landlock_hook_type hook_type = LANDLOCK_HOOK_FS_WALK;
+
+ if (!current_has_prog_type(hook_type))
+ /* no fs_walk */
+ return 0;
+ if (WARN_ON(!inode))
+ return -EFAULT;
+
+ /* init common data: inode, is_dot, is_dotdot, is_root */
+ fs_walk.prog_ctx.inode = (uintptr_t)inode;
+ return landlock_decide(hook_type, &hook_ctx, 0);
+}
+
+/* fs_pick */
+
+struct landlock_hook_ctx_fs_pick {
+ __u64 triggers;
+ struct landlock_ctx_fs_pick prog_ctx;
+};
+
+const struct landlock_ctx_fs_pick *landlock_get_ctx_fs_pick(
+ const struct landlock_hook_ctx_fs_pick *hook_ctx)
+{
+ if (WARN_ON(!hook_ctx))
+ return NULL;
+
+ return &hook_ctx->prog_ctx;
+}
+
+static int decide_fs_pick(__u64 triggers, struct inode *inode)
+{
+ struct landlock_hook_ctx_fs_pick fs_pick = {};
+ struct landlock_hook_ctx hook_ctx = {
+ .fs_pick = &fs_pick,
+ };
+ const enum landlock_hook_type hook_type = LANDLOCK_HOOK_FS_PICK;
+
+ if (WARN_ON(!triggers))
+ return 0;
+ if (!current_has_prog_type(hook_type))
+ /* no fs_pick */
+ return 0;
+ if (WARN_ON(!inode))
+ return -EFAULT;
+
+ fs_pick.triggers = triggers,
+ /* init common data: inode */
+ fs_pick.prog_ctx.inode = (uintptr_t)inode;
+ return landlock_decide(hook_type, &hook_ctx, fs_pick.triggers);
+}
+
+/* helpers */
+
+static u64 fs_may_to_triggers(int may_mask, umode_t mode)
+{
+ u64 ret = 0;
+
+ if (may_mask & MAY_EXEC)
+ ret |= LANDLOCK_TRIGGER_FS_PICK_EXECUTE;
+ if (may_mask & MAY_READ) {
+ if (S_ISDIR(mode))
+ ret |= LANDLOCK_TRIGGER_FS_PICK_READDIR;
+ else
+ ret |= LANDLOCK_TRIGGER_FS_PICK_READ;
+ }
+ if (may_mask & MAY_WRITE)
+ ret |= LANDLOCK_TRIGGER_FS_PICK_WRITE;
+ if (may_mask & MAY_APPEND)
+ ret |= LANDLOCK_TRIGGER_FS_PICK_APPEND;
+ if (may_mask & MAY_OPEN)
+ ret |= LANDLOCK_TRIGGER_FS_PICK_OPEN;
+ if (may_mask & MAY_CHROOT)
+ ret |= LANDLOCK_TRIGGER_FS_PICK_CHROOT;
+ else if (may_mask & MAY_CHDIR)
+ ret |= LANDLOCK_TRIGGER_FS_PICK_CHDIR;
+ /* XXX: ignore MAY_ACCESS */
+ WARN_ON(!ret);
+ return ret;
+}
+
+static inline u64 mem_prot_to_triggers(unsigned long prot, bool private)
+{
+ u64 ret = LANDLOCK_TRIGGER_FS_PICK_MAP;
+
+ /* private mapping do not write to files */
+ if (!private && (prot & PROT_WRITE))
+ ret |= LANDLOCK_TRIGGER_FS_PICK_WRITE;
+ if (prot & PROT_READ)
+ ret |= LANDLOCK_TRIGGER_FS_PICK_READ;
+ if (prot & PROT_EXEC)
+ ret |= LANDLOCK_TRIGGER_FS_PICK_EXECUTE;
+ WARN_ON(!ret);
+ return ret;
+}
+
+/* binder hooks */
+
+static int hook_binder_transfer_file(struct task_struct *from,
+ struct task_struct *to, struct file *file)
+{
+ if (!landlocked(current))
+ return 0;
+ if (WARN_ON(!file))
+ return 0;
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_TRANSFER,
+ file_inode(file));
+}
+
+/* sb hooks */
+
+static int hook_sb_statfs(struct dentry *dentry)
+{
+ if (!landlocked(current))
+ return 0;
+ if (WARN_ON(!dentry))
+ return 0;
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_GETATTR,
+ dentry->d_inode);
+}
+
+/* TODO: handle mount source and remount */
+static int hook_sb_mount(const char *dev_name, const struct path *path,
+ const char *type, unsigned long flags, void *data)
+{
+ if (!landlocked(current))
+ return 0;
+ if (WARN_ON(!path))
+ return 0;
+ if (WARN_ON(!path->dentry))
+ return 0;
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_MOUNTON,
+ path->dentry->d_inode);
+}
+
+/*
+ * The @old_path is similar to a destination mount point.
+ */
+static int hook_sb_pivotroot(const struct path *old_path,
+ const struct path *new_path)
+{
+ int err;
+
+ if (!landlocked(current))
+ return 0;
+ if (WARN_ON(!old_path))
+ return 0;
+ if (WARN_ON(!old_path->dentry))
+ return 0;
+ err = decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_MOUNTON,
+ old_path->dentry->d_inode);
+ if (err)
+ return err;
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_CHROOT,
+ new_path->dentry->d_inode);
+}
+
+/* inode hooks */
+
+/* a directory inode contains only one dentry */
+static int hook_inode_create(struct inode *dir, struct dentry *dentry,
+ umode_t mode)
+{
+ if (!landlocked(current))
+ return 0;
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_CREATE, dir);
+}
+
+static int hook_inode_link(struct dentry *old_dentry, struct inode *dir,
+ struct dentry *new_dentry)
+{
+ if (!landlocked(current))
+ return 0;
+ if (WARN_ON(!old_dentry)) {
+ int ret = decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_LINK,
+ old_dentry->d_inode);
+ if (ret)
+ return ret;
+ }
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_LINKTO, dir);
+}
+
+static int hook_inode_unlink(struct inode *dir, struct dentry *dentry)
+{
+ if (!landlocked(current))
+ return 0;
+ if (WARN_ON(!dentry))
+ return 0;
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_UNLINK,
+ dentry->d_inode);
+}
+
+static int hook_inode_symlink(struct inode *dir, struct dentry *dentry,
+ const char *old_name)
+{
+ if (!landlocked(current))
+ return 0;
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_CREATE, dir);
+}
+
+static int hook_inode_mkdir(struct inode *dir, struct dentry *dentry,
+ umode_t mode)
+{
+ if (!landlocked(current))
+ return 0;
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_CREATE, dir);
+}
+
+static int hook_inode_rmdir(struct inode *dir, struct dentry *dentry)
+{
+ if (!landlocked(current))
+ return 0;
+ if (WARN_ON(!dentry))
+ return 0;
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_RMDIR, dentry->d_inode);
+}
+
+static int hook_inode_mknod(struct inode *dir, struct dentry *dentry,
+ umode_t mode, dev_t dev)
+{
+ if (!landlocked(current))
+ return 0;
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_CREATE, dir);
+}
+
+static int hook_inode_rename(struct inode *old_dir, struct dentry *old_dentry,
+ struct inode *new_dir, struct dentry *new_dentry)
+{
+ if (!landlocked(current))
+ return 0;
+ /* TODO: add artificial walk session from old_dir to old_dentry */
+ if (!WARN_ON(!old_dentry)) {
+ int ret = decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_RENAME,
+ old_dentry->d_inode);
+ if (ret)
+ return ret;
+ }
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_RENAMETO, new_dir);
+}
+
+static int hook_inode_readlink(struct dentry *dentry)
+{
+ if (!landlocked(current))
+ return 0;
+ if (WARN_ON(!dentry))
+ return 0;
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_READ, dentry->d_inode);
+}
+
+/*
+ * ignore the inode_follow_link hook (could set is_symlink in the fs_walk
+ * context)
+ */
+
+static int hook_inode_permission(struct inode *inode, int mask)
+{
+ u64 triggers;
+
+ if (!landlocked(current))
+ return 0;
+ if (WARN_ON(!inode))
+ return 0;
+
+ triggers = fs_may_to_triggers(mask, inode->i_mode);
+ /*
+ * decide_fs_walk() is exclusive with decide_fs_pick(): in a path walk,
+ * ignore execute-only access on directory for any fs_pick program
+ */
+ if (triggers == LANDLOCK_TRIGGER_FS_PICK_EXECUTE &&
+ S_ISDIR(inode->i_mode))
+ return decide_fs_walk(mask, inode);
+
+ return decide_fs_pick(triggers, inode);
+}
+
+static int hook_inode_setattr(struct dentry *dentry, struct iattr *attr)
+{
+ if (!landlocked(current))
+ return 0;
+ if (WARN_ON(!dentry))
+ return 0;
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_SETATTR,
+ dentry->d_inode);
+}
+
+static int hook_inode_getattr(const struct path *path)
+{
+ /* TODO: link parent inode and path */
+ if (!landlocked(current))
+ return 0;
+ if (WARN_ON(!path))
+ return 0;
+ if (WARN_ON(!path->dentry))
+ return 0;
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_GETATTR,
+ path->dentry->d_inode);
+}
+
+static int hook_inode_setxattr(struct dentry *dentry, const char *name,
+ const void *value, size_t size, int flags)
+{
+ if (!landlocked(current))
+ return 0;
+ if (WARN_ON(!dentry))
+ return 0;
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_SETATTR,
+ dentry->d_inode);
+}
+
+static int hook_inode_getxattr(struct dentry *dentry, const char *name)
+{
+ if (!landlocked(current))
+ return 0;
+ if (WARN_ON(!dentry))
+ return 0;
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_GETATTR,
+ dentry->d_inode);
+}
+
+static int hook_inode_listxattr(struct dentry *dentry)
+{
+ if (!landlocked(current))
+ return 0;
+ if (WARN_ON(!dentry))
+ return 0;
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_GETATTR,
+ dentry->d_inode);
+}
+
+static int hook_inode_removexattr(struct dentry *dentry, const char *name)
+{
+ if (!landlocked(current))
+ return 0;
+ if (WARN_ON(!dentry))
+ return 0;
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_SETATTR,
+ dentry->d_inode);
+}
+
+static int hook_inode_getsecurity(struct inode *inode, const char *name,
+ void **buffer, bool alloc)
+{
+ if (!landlocked(current))
+ return 0;
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_GETATTR, inode);
+}
+
+static int hook_inode_setsecurity(struct inode *inode, const char *name,
+ const void *value, size_t size, int flag)
+{
+ if (!landlocked(current))
+ return 0;
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_SETATTR, inode);
+}
+
+static int hook_inode_listsecurity(struct inode *inode, char *buffer,
+ size_t buffer_size)
+{
+ if (!landlocked(current))
+ return 0;
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_GETATTR, inode);
+}
+
+/* file hooks */
+
+static int hook_file_ioctl(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ if (!landlocked(current))
+ return 0;
+ if (WARN_ON(!file))
+ return 0;
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_IOCTL,
+ file_inode(file));
+}
+
+static int hook_file_lock(struct file *file, unsigned int cmd)
+{
+ if (!landlocked(current))
+ return 0;
+ if (WARN_ON(!file))
+ return 0;
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_LOCK, file_inode(file));
+}
+
+static int hook_file_fcntl(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ if (!landlocked(current))
+ return 0;
+ if (WARN_ON(!file))
+ return 0;
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_FCNTL,
+ file_inode(file));
+}
+
+static int hook_mmap_file(struct file *file, unsigned long reqprot,
+ unsigned long prot, unsigned long flags)
+{
+ if (!landlocked(current))
+ return 0;
+ /* file can be null for anonymous mmap */
+ if (!file)
+ return 0;
+ return decide_fs_pick(mem_prot_to_triggers(prot, flags & MAP_PRIVATE),
+ file_inode(file));
+}
+
+static int hook_file_mprotect(struct vm_area_struct *vma,
+ unsigned long reqprot, unsigned long prot)
+{
+ if (!landlocked(current))
+ return 0;
+ if (WARN_ON(!vma))
+ return 0;
+ if (!vma->vm_file)
+ return 0;
+ return decide_fs_pick(mem_prot_to_triggers(prot,
+ !(vma->vm_flags & VM_SHARED)),
+ file_inode(vma->vm_file));
+}
+
+static int hook_file_receive(struct file *file)
+{
+ if (!landlocked(current))
+ return 0;
+ if (WARN_ON(!file))
+ return 0;
+ return decide_fs_pick(LANDLOCK_TRIGGER_FS_PICK_RECEIVE,
+ file_inode(file));
+}
+
+static struct security_hook_list landlock_hooks[] = {
+ LSM_HOOK_INIT(binder_transfer_file, hook_binder_transfer_file),
+
+ LSM_HOOK_INIT(sb_statfs, hook_sb_statfs),
+ LSM_HOOK_INIT(sb_mount, hook_sb_mount),
+ LSM_HOOK_INIT(sb_pivotroot, hook_sb_pivotroot),
+
+ LSM_HOOK_INIT(inode_create, hook_inode_create),
+ LSM_HOOK_INIT(inode_link, hook_inode_link),
+ LSM_HOOK_INIT(inode_unlink, hook_inode_unlink),
+ LSM_HOOK_INIT(inode_symlink, hook_inode_symlink),
+ LSM_HOOK_INIT(inode_mkdir, hook_inode_mkdir),
+ LSM_HOOK_INIT(inode_rmdir, hook_inode_rmdir),
+ LSM_HOOK_INIT(inode_mknod, hook_inode_mknod),
+ LSM_HOOK_INIT(inode_rename, hook_inode_rename),
+ LSM_HOOK_INIT(inode_readlink, hook_inode_readlink),
+ LSM_HOOK_INIT(inode_permission, hook_inode_permission),
+ LSM_HOOK_INIT(inode_setattr, hook_inode_setattr),
+ LSM_HOOK_INIT(inode_getattr, hook_inode_getattr),
+ LSM_HOOK_INIT(inode_setxattr, hook_inode_setxattr),
+ LSM_HOOK_INIT(inode_getxattr, hook_inode_getxattr),
+ LSM_HOOK_INIT(inode_listxattr, hook_inode_listxattr),
+ LSM_HOOK_INIT(inode_removexattr, hook_inode_removexattr),
+ LSM_HOOK_INIT(inode_getsecurity, hook_inode_getsecurity),
+ LSM_HOOK_INIT(inode_setsecurity, hook_inode_setsecurity),
+ LSM_HOOK_INIT(inode_listsecurity, hook_inode_listsecurity),
+
+ /* do not handle file_permission for now */
+ LSM_HOOK_INIT(file_ioctl, hook_file_ioctl),
+ LSM_HOOK_INIT(file_lock, hook_file_lock),
+ LSM_HOOK_INIT(file_fcntl, hook_file_fcntl),
+ LSM_HOOK_INIT(mmap_file, hook_mmap_file),
+ LSM_HOOK_INIT(file_mprotect, hook_file_mprotect),
+ LSM_HOOK_INIT(file_receive, hook_file_receive),
+ /* file_open is not handled, use inode_permission instead */
+};
+
+__init void landlock_add_hooks_fs(void)
+{
+ security_add_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks),
+ LANDLOCK_NAME);
+}
diff --git a/security/landlock/hooks_fs.h b/security/landlock/hooks_fs.h
new file mode 100644
index 000000000000..eeae4dcd842f
--- /dev/null
+++ b/security/landlock/hooks_fs.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Landlock LSM - filesystem hooks
+ *
+ * Copyright © 2017-2019 Mickaël Salaün <mic@digikod.net>
+ * Copyright © 2018-2019 ANSSI
+ */
+
+#include <linux/bpf.h> /* enum bpf_access_type */
+
+__init void landlock_add_hooks_fs(void);
+
+/* fs_pick */
+
+struct landlock_hook_ctx_fs_pick;
+
+bool landlock_is_valid_access_fs_pick(int off, enum bpf_access_type type,
+ enum bpf_reg_type *reg_type, int *max_size);
+
+const struct landlock_ctx_fs_pick *landlock_get_ctx_fs_pick(
+ const struct landlock_hook_ctx_fs_pick *hook_ctx);
+
+/* fs_walk */
+
+struct landlock_hook_ctx_fs_walk;
+
+bool landlock_is_valid_access_fs_walk(int off, enum bpf_access_type type,
+ enum bpf_reg_type *reg_type, int *max_size);
+
+const struct landlock_ctx_fs_walk *landlock_get_ctx_fs_walk(
+ const struct landlock_hook_ctx_fs_walk *hook_ctx);
diff --git a/security/landlock/init.c b/security/landlock/init.c
index 03073cd0fc4e..68def2a7af71 100644
--- a/security/landlock/init.c
+++ b/security/landlock/init.c
@@ -9,8 +9,10 @@
#include <linux/bpf.h> /* enum bpf_access_type */
#include <linux/capability.h> /* capable */
#include <linux/filter.h> /* struct bpf_prog */
+#include <linux/lsm_hooks.h>
#include "common.h" /* LANDLOCK_* */
+#include "hooks_fs.h"
static bool bpf_landlock_is_valid_access(int off, int size,
enum bpf_access_type type, const struct bpf_prog *prog,
@@ -29,6 +31,23 @@ static bool bpf_landlock_is_valid_access(int off, int size,
if (size <= 0 || size > sizeof(__u64))
return false;
+ /* set register type and max size */
+ switch (prog_subtype->landlock_hook.type) {
+ case LANDLOCK_HOOK_FS_PICK:
+ if (!landlock_is_valid_access_fs_pick(off, type, ®_type,
+ &max_size))
+ return false;
+ break;
+ case LANDLOCK_HOOK_FS_WALK:
+ if (!landlock_is_valid_access_fs_walk(off, type, ®_type,
+ &max_size))
+ return false;
+ break;
+ default:
+ WARN_ON(1);
+ return false;
+ }
+
/* check memory range access */
switch (reg_type) {
case NOT_INIT:
@@ -98,6 +117,18 @@ static const struct bpf_func_proto *bpf_landlock_func_proto(
default:
break;
}
+
+ switch (hook_type) {
+ case LANDLOCK_HOOK_FS_WALK:
+ case LANDLOCK_HOOK_FS_PICK:
+ switch (func_id) {
+ case BPF_FUNC_inode_map_lookup:
+ return &bpf_inode_map_lookup_proto;
+ default:
+ break;
+ }
+ break;
+ }
return NULL;
}
@@ -108,3 +139,19 @@ const struct bpf_verifier_ops landlock_verifier_ops = {
};
const struct bpf_prog_ops landlock_prog_ops = {};
+
+static int __init landlock_init(void)
+{
+ pr_info(LANDLOCK_NAME ": Initializing (sandbox with seccomp)\n");
+ landlock_add_hooks_fs();
+ return 0;
+}
+
+struct lsm_blob_sizes landlock_blob_sizes __lsm_ro_after_init = {};
+
+DEFINE_LSM(LANDLOCK_NAME) = {
+ .name = LANDLOCK_NAME,
+ .order = LSM_ORDER_LAST,
+ .blobs = &landlock_blob_sizes,
+ .init = landlock_init,
+};
diff --git a/security/security.c b/security/security.c
index f493db0bf62a..05a23995407d 100644
--- a/security/security.c
+++ b/security/security.c
@@ -263,6 +263,21 @@ static void __init ordered_lsm_parse(const char *order, const char *origin)
}
}
+ /*
+ * In case of an unprivileged access-control, we don't want to give the
+ * ability to any process to do some checks (e.g. through an eBPF
+ * program) on kernel objects (e.g. files) if a privileged security
+ * policy forbid their access. We must then load
+ * potentially-unprivileged security modules after all other LSMs.
+ *
+ * LSM_ORDER_LAST is always last and does not appear in the modifiable
+ * ordered list of enabled LSMs.
+ */
+ for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) {
+ if (lsm->order == LSM_ORDER_LAST)
+ append_ordered_lsm(lsm, "last");
+ }
+
/* Disable all LSMs not in the ordered list. */
for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) {
if (exists_ordered_lsm(lsm))
--
2.20.1
^ permalink raw reply related
* [PATCH bpf-next v9 00/10] Landlock LSM: Toward unprivileged sandboxing
From: Mickaël Salaün @ 2019-06-25 21:52 UTC (permalink / raw)
To: linux-kernel
Cc: Mickaël Salaün, Aleksa Sarai, Alexander Viro,
Alexei Starovoitov, Andrew Morton, Andy Lutomirski,
Arnaldo Carvalho de Melo, Casey Schaufler, Daniel Borkmann,
David Drysdale, David S . Miller, Eric W . Biederman,
James Morris, Jann Horn, John Johansen, Jonathan Corbet,
Kees Cook, Michael Kerrisk, Mickaël Salaün, Paul Moore,
Sargun Dhillon, Serge E . Hallyn, Shuah Khan, Stephen Smalley,
Tejun Heo, Tetsuo Handa, Thomas Graf, Tycho Andersen, Will Drewry,
kernel-hardening, linux-api, linux-fsdevel, linux-security-module,
netdev
Hi,
This ninth series upgrade Landlock as a stackable LSM [4] and elide the
file system path evaluation from the previous series [1] to make this
review process easier. This patch series is almost half the size of the
previous one.
Landlock is a low-level framework to build custom access-control systems
or safe endpoint security agents. There is two types of Landlock hooks:
FS_WALK and FS_PICK. Each of them accepts a dedicated eBPF program,
called a Landlock program. The set of actions on a file is well defined
(e.g. read, write, ioctl, append, lock, mount...) taking inspiration
from the major Linux LSMs and some other access-controls like Capsicum.
The example patch show how a file system access control can be built
based on a list of denied files and directories. From a security point
of view, it may be preferable to use a whitelist instead of a blacklist,
but this series only enable to match a specific list of files. Bringing
back a way to evaluate a path is planned for a future dedicated series,
once this base Landlock framework is merged. I may take inspiration
from the LOOKUP_BENEATH approach [5], but from an eBPF point of view.
The documentation patch contains some kernel documentation and
explanations on how to use Landlock. The compiled documentation and
some talks can be found here: https://landlock.io
This patch series can be found in a Git repository here:
https://github.com/landlock-lsm/linux/commits/landlock-v9
There is still some minor issues with this patch series but it is enough
to get a deep review.
This is the first step of the roadmap discussed at LPC [2]. While the
intended final goal is to allow unprivileged users to use Landlock, this
series allows only a process with global CAP_SYS_ADMIN to load and
enforce a rule. This may help to get feedback and avoid unexpected
behaviors.
This series can be applied on top of bpf-next, commit 88091ff56b71
("selftests, bpf: Add test for veth native XDP"). This can be tested
with CONFIG_SECCOMP_FILTER and CONFIG_SECURITY_LANDLOCK. I would really
appreciate constructive comments on the design and the code.
# Landlock LSM
The goal of this new Linux Security Module (LSM) called Landlock is to
allow any process, including unprivileged ones, to create powerful
security sandboxes comparable to XNU Sandbox or OpenBSD Pledge (which
could be implemented with Landlock). This kind of sandbox is expected
to help mitigate the security impact of bugs or unexpected/malicious
behaviors in user-space applications.
The approach taken is to add the minimum amount of code while still
allowing the user-space application to create quite complex access
rules. A dedicated security policy language such as the one used by
SELinux, AppArmor and other major LSMs involves a lot of code and is
usually permitted to only a trusted user (i.e. root). On the contrary,
eBPF programs already exist and are designed to be safely loaded by
unprivileged user-space.
This design does not seem too intrusive but is flexible enough to allow
a powerful sandbox mechanism accessible by any process on Linux. The use
of seccomp and Landlock is more suitable with the help of a user-space
library (e.g. libseccomp) that could help to specify a high-level
language to express a security policy instead of raw eBPF programs.
Moreover, thanks to the LLVM front-end, it is quite easy to write an
eBPF program with a subset of the C language.
# Frequently asked questions
## Why is seccomp-bpf not enough?
A seccomp filter can access only raw syscall arguments (i.e. the
register values) which means that it is not possible to filter according
to the value pointed to by an argument, such as a file pathname. As an
embryonic Landlock version demonstrated, filtering at the syscall level
is complicated (e.g. need to take care of race conditions). This is
mainly because the access control checkpoints of the kernel are not at
this high-level but more underneath, at the LSM-hook level. The LSM
hooks are designed to handle this kind of checks. Landlock abstracts
this approach to leverage the ability of unprivileged users to limit
themselves.
Cf. section "What it isn't?" in Documentation/prctl/seccomp_filter.txt
## Why use the seccomp(2) syscall?
Landlock use the same semantic as seccomp to apply access rule
restrictions. It add a new layer of security for the current process
which is inherited by its children. It makes sense to use an unique
access-restricting syscall (that should be allowed by seccomp filters)
which can only drop privileges. Moreover, a Landlock rule could come
from outside a process (e.g. passed through a UNIX socket). It is then
useful to differentiate the creation/load of Landlock eBPF programs via
bpf(2), from rule enforcement via seccomp(2).
## Why a new LSM? Are SELinux, AppArmor, Smack and Tomoyo not good
enough?
The current access control LSMs are fine for their purpose which is to
give the *root* the ability to enforce a security policy for the
*system*. What is missing is a way to enforce a security policy for any
application by its developer and *unprivileged user* as seccomp can do
for raw syscall filtering.
Differences from other (access control) LSMs:
* not only dedicated to administrators (i.e. no_new_priv);
* limited kernel attack surface (e.g. policy parsing);
* constrained policy rules (no DoS: deterministic execution time);
* do not leak more information than the loader process can legitimately
have access to (minimize metadata inference).
# Changes since v8
* fit with the new LSM stacking framework (security blobs were tested
but are not use in this series because of the code reduction)
* remove the Landlock program chaining and the file path evaluation
feature to get a minimum viable product and ease the review
* replace the example with a simple blacklist policy
* rebase on bpf-next
# Changes since v7
* major revamp of the file system enforcement:
* new eBPF map dedicated to tie an inode with an arbitrary 64-bits
value, which can be used to tag files
* three new Landlock hooks: FS_WALK, FS_PICK and FS_GET
* add the ability to chain Landlock programs
* add a new eBPF map type to compare inodes
* don't use macros anymore
* replace subtype fields:
* triggers: fine-grained bitfiel of actions on which a Landlock
program may be called (if it comes from a sandbox process)
* previous: a parent chained program
* upstreamed patches:
* commit 369130b63178 ("selftests: Enhance kselftest_harness.h to
print which assert failed")
# Changes since v6
* upstreamed patches:
* commit 752ba56fb130 ("bpf: Extend check_uarg_tail_zero() checks")
* commit 0b40808a1084 ("selftests: Make test_harness.h more generally
available") and related ones
* commit 3bb857e47e49 ("LSM: Enable multiple calls to
security_add_hooks() for the same LSM")
* simplify the landlock_context (remove syscall_* fields) and add three
FS sub-events: IOCTL, LOCK, FCNTL
* minimize the number of callable BPF functions from a Landlock rule
* do not split put_seccomp_filter() with put_seccomp()
* rename Landlock version to Landlock ABI
* miscellaneous fixes
* rebase on net-next
# Changes since v5
* eBPF program subtype:
* use a prog_subtype pointer instead of inlining it into bpf_attr
* enable a future-proof behavior (reject unhandled data/size)
* add tests
* use a simple rule hierarchy (similar to seccomp-bpf)
* add a ptrace scope protection
* add more tests
* add more documentation
* rename some files
* miscellaneous fixes
* rebase on net-next
# Changes since v4
* upstreamed patches:
* commit d498f8719a09 ("bpf: Rebuild bpf.o for any dependency update")
* commit a734fb5d6006 ("samples/bpf: Reset global variables") and
related ones
* commit f4874d01beba ("bpf: Use bpf_create_map() from the library")
and related ones
* commit d02d8986a768 ("bpf: Always test unprivileged programs")
* commit 640eb7e7b524 ("fs: Constify path_is_under()'s arguments")
* commit 535e7b4b5ef2 ("bpf: Use u64_to_user_ptr()")
* revamp Landlock to not expose an LSM hook interface but wrap and
abstract them with Landlock events (currently one for all filesystem
related operations: LANDLOCK_SUBTYPE_EVENT_FS)
* wrap all filesystem kernel objects through the same FS handle (struct
landlock_handle_fs): struct file, struct inode, struct path and struct
dentry
* a rule don't return an errno code but only a boolean to allow or deny
an access request
* handle all filesystem related LSM hooks
* add some tests and a sample:
* BPF context tests
* Landlock sandboxing tests and sample
* write Landlock rules in C and compile them with LLVM
* change field names of eBPF program subtype
* remove arraymap of handles for now (will be replaced with a revamped
map)
* remove cgroup handling for now
* add user and kernel documentation
* rebase on net-next
# Changes since v3
* upstreamed patch:
* commit 1955351da41c ("bpf: Set register type according to
is_valid_access()")
* use abstract LSM hook arguments with custom types (e.g.
*_LANDLOCK_ARG_FS for struct file, struct inode and struct path)
* add more LSM hooks to support full filesystem access control
* improve the sandbox example
* fix races and RCU issues:
* eBPF program execution and eBPF helpers
* revamp the arraymap of handles to cleanly deal with update/delete
* eBPF program subtype for Landlock:
* remove the "origin" field
* add an "option" field
* rebase onto Daniel Mack's patches v7 [3]
* remove merged commit 1955351da41c ("bpf: Set register type according
to is_valid_access()")
* fix spelling mistakes
* cleanup some type and variable names
* split patches
* for now, remove cgroup delegation handling for unprivileged user
* remove extra access check for cgroup_get_from_fd()
* remove unused example code dealing with skb
* remove seccomp-bpf link:
* no more seccomp cookie
* for now, it is no more possible to check the current syscall
properties
# Changes since v2
* revamp cgroup handling:
* use Daniel Mack's patches "Add eBPF hooks for cgroups" v5
* remove bpf_landlock_cmp_cgroup_beneath()
* make BPF_PROG_ATTACH usable with delegated cgroups
* add a new CGRP_NO_NEW_PRIVS flag for safe cgroups
* handle Landlock sandboxing for cgroups hierarchy
* allow unprivileged processes to attach Landlock eBPF program to
cgroups
* add subtype to eBPF programs:
* replace Landlock hook identification by custom eBPF program types
with a dedicated subtype field
* manage fine-grained privileged Landlock programs
* register Landlock programs for dedicated trigger origins (e.g.
syscall, return from seccomp filter and/or interruption)
* performance and memory optimizations: use an array to access Landlock
hooks directly but do not duplicated it for each thread
(seccomp-based)
* allow running Landlock programs without seccomp filter
* fix seccomp-related issues
* remove extra errno bounding check for Landlock programs
* add some examples for optional eBPF functions or context access
(network related) according to security checks to allow more features
for privileged programs (e.g. Checmate)
# Changes since v1
* focus on the LSM hooks, not the syscalls:
* much more simple implementation
* does not need audit cache tricks to avoid race conditions
* more simple to use and more generic because using the LSM hook
abstraction directly
* more efficient because only checking in LSM hooks
* architecture agnostic
* switch from cBPF to eBPF:
* new eBPF program types dedicated to Landlock
* custom functions used by the eBPF program
* gain some new features (e.g. 10 registers, can load values of
different size, LLVM translator) but only a few functions allowed
and a dedicated map type
* new context: LSM hook ID, cookie and LSM hook arguments
* need to set the sysctl kernel.unprivileged_bpf_disable to 0 (default
value) to be able to load hook filters as unprivileged users
* smaller and simpler:
* no more checker groups but dedicated arraymap of handles
* simpler userland structs thanks to eBPF functions
* distinctive name: Landlock
[1] https://lore.kernel.org/lkml/20180227004121.3633-1-mic@digikod.net/
[2] https://lore.kernel.org/lkml/5828776A.1010104@digikod.net/
[3] https://lore.kernel.org/netdev/1477390454-12553-1-git-send-email-daniel@zonque.org/
[4] https://lore.kernel.org/lkml/50db058a-7dde-441b-a7f9-f6837fe8b69f@schaufler-ca.com/
[5] https://lore.kernel.org/lkml/20190520133305.11925-1-cyphar@cyphar.com/
Regards,
Mickaël Salaün (10):
fs,security: Add a new file access type: MAY_CHROOT
bpf: Add eBPF program subtype and is_valid_subtype() verifier
bpf,landlock: Define an eBPF program type for Landlock hooks
seccomp,landlock: Enforce Landlock programs per process hierarchy
bpf,landlock: Add a new map type: inode
landlock: Handle filesystem access control
landlock: Add ptrace restrictions
bpf: Add a Landlock sandbox example
bpf,landlock: Add tests for Landlock
landlock: Add user and kernel documentation for Landlock
Documentation/security/index.rst | 1 +
Documentation/security/landlock/index.rst | 20 +
Documentation/security/landlock/kernel.rst | 99 +++
Documentation/security/landlock/user.rst | 148 +++++
MAINTAINERS | 13 +
fs/open.c | 3 +-
include/linux/bpf.h | 17 +
include/linux/bpf_types.h | 6 +
include/linux/fs.h | 1 +
include/linux/landlock.h | 34 ++
include/linux/lsm_hooks.h | 1 +
include/linux/seccomp.h | 5 +
include/uapi/linux/bpf.h | 22 +-
include/uapi/linux/landlock.h | 109 ++++
include/uapi/linux/seccomp.h | 1 +
kernel/bpf/Makefile | 3 +
kernel/bpf/core.c | 3 +
kernel/bpf/inodemap.c | 315 ++++++++++
kernel/bpf/syscall.c | 59 +-
kernel/bpf/verifier.c | 25 +
kernel/fork.c | 8 +-
kernel/seccomp.c | 4 +
net/core/filter.c | 25 +-
samples/bpf/.gitignore | 1 +
samples/bpf/Makefile | 3 +
samples/bpf/bpf_load.c | 76 ++-
samples/bpf/bpf_load.h | 7 +
samples/bpf/landlock1.h | 8 +
samples/bpf/landlock1_kern.c | 104 ++++
samples/bpf/landlock1_user.c | 157 +++++
security/Kconfig | 1 +
security/Makefile | 2 +
security/landlock/Kconfig | 18 +
security/landlock/Makefile | 5 +
security/landlock/common.h | 81 +++
security/landlock/enforce.c | 272 +++++++++
security/landlock/enforce.h | 18 +
security/landlock/enforce_seccomp.c | 92 +++
security/landlock/hooks.c | 95 +++
security/landlock/hooks.h | 31 +
security/landlock/hooks_fs.c | 568 ++++++++++++++++++
security/landlock/hooks_fs.h | 31 +
security/landlock/hooks_ptrace.c | 121 ++++
security/landlock/hooks_ptrace.h | 8 +
security/landlock/init.c | 159 +++++
security/security.c | 15 +
tools/include/uapi/linux/bpf.h | 22 +-
tools/include/uapi/linux/landlock.h | 109 ++++
tools/lib/bpf/bpf.c | 10 +-
tools/lib/bpf/bpf.h | 2 +
tools/lib/bpf/libbpf.c | 1 +
tools/lib/bpf/libbpf.map | 1 +
tools/lib/bpf/libbpf_probes.c | 2 +
tools/testing/selftests/Makefile | 1 +
tools/testing/selftests/bpf/bpf_helpers.h | 2 +
tools/testing/selftests/bpf/test_verifier.c | 27 +-
.../testing/selftests/bpf/verifier/landlock.c | 35 ++
.../testing/selftests/bpf/verifier/subtype.c | 20 +
tools/testing/selftests/landlock/.gitignore | 4 +
tools/testing/selftests/landlock/Makefile | 39 ++
tools/testing/selftests/landlock/test.h | 48 ++
tools/testing/selftests/landlock/test_base.c | 24 +
tools/testing/selftests/landlock/test_fs.c | 257 ++++++++
.../testing/selftests/landlock/test_ptrace.c | 154 +++++
64 files changed, 3528 insertions(+), 25 deletions(-)
create mode 100644 Documentation/security/landlock/index.rst
create mode 100644 Documentation/security/landlock/kernel.rst
create mode 100644 Documentation/security/landlock/user.rst
create mode 100644 include/linux/landlock.h
create mode 100644 include/uapi/linux/landlock.h
create mode 100644 kernel/bpf/inodemap.c
create mode 100644 samples/bpf/landlock1.h
create mode 100644 samples/bpf/landlock1_kern.c
create mode 100644 samples/bpf/landlock1_user.c
create mode 100644 security/landlock/Kconfig
create mode 100644 security/landlock/Makefile
create mode 100644 security/landlock/common.h
create mode 100644 security/landlock/enforce.c
create mode 100644 security/landlock/enforce.h
create mode 100644 security/landlock/enforce_seccomp.c
create mode 100644 security/landlock/hooks.c
create mode 100644 security/landlock/hooks.h
create mode 100644 security/landlock/hooks_fs.c
create mode 100644 security/landlock/hooks_fs.h
create mode 100644 security/landlock/hooks_ptrace.c
create mode 100644 security/landlock/hooks_ptrace.h
create mode 100644 security/landlock/init.c
create mode 100644 tools/include/uapi/linux/landlock.h
create mode 100644 tools/testing/selftests/bpf/verifier/landlock.c
create mode 100644 tools/testing/selftests/bpf/verifier/subtype.c
create mode 100644 tools/testing/selftests/landlock/.gitignore
create mode 100644 tools/testing/selftests/landlock/Makefile
create mode 100644 tools/testing/selftests/landlock/test.h
create mode 100644 tools/testing/selftests/landlock/test_base.c
create mode 100644 tools/testing/selftests/landlock/test_fs.c
create mode 100644 tools/testing/selftests/landlock/test_ptrace.c
--
2.20.1
^ permalink raw reply
* [PATCH bpf-next v9 05/10] bpf,landlock: Add a new map type: inode
From: Mickaël Salaün @ 2019-06-25 21:52 UTC (permalink / raw)
To: linux-kernel
Cc: Mickaël Salaün, Aleksa Sarai, Alexander Viro,
Alexei Starovoitov, Andrew Morton, Andy Lutomirski,
Arnaldo Carvalho de Melo, Casey Schaufler, Daniel Borkmann,
David Drysdale, David S . Miller, Eric W . Biederman,
James Morris, Jann Horn, John Johansen, Jonathan Corbet,
Kees Cook, Michael Kerrisk, Mickaël Salaün, Paul Moore,
Sargun Dhillon, Serge E . Hallyn, Shuah Khan, Stephen Smalley,
Tejun Heo, Tetsuo Handa, Thomas Graf, Tycho Andersen, Will Drewry,
kernel-hardening, linux-api, linux-fsdevel, linux-security-module,
netdev
In-Reply-To: <20190625215239.11136-1-mic@digikod.net>
This new map store arbitrary 64-bits values referenced by inode keys.
The map can be updated from user space with file descriptor pointing to
inodes tied to a file system. From an eBPF (Landlock) program point of
view, such a map is read-only and can only be used to retrieved a
64-bits value tied to a given inode. This is useful to recognize an
inode tagged by user space, without access right to this inode (i.e. no
need to have a write access to this inode).
Add dedicated BPF functions to handle this type of map:
* bpf_inode_map_update_elem()
* bpf_inode_map_lookup_elem()
* bpf_inode_map_delete_elem()
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: James Morris <jmorris@namei.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Serge E. Hallyn <serge@hallyn.com>
Cc: Jann Horn <jann@thejh.net>
---
Changes since v8:
* remove prog chaining and object tagging to ease review
* use bpf_map_init_from_attr()
Changes since v7:
* new design with a dedicated map and a BPF function to tie a value to
an inode
* add the ability to set or get a tag on an inode from a Landlock
program
Changes since v6:
* remove WARN_ON() for missing dentry->d_inode
* refactor bpf_landlock_func_proto() (suggested by Kees Cook)
Changes since v5:
* cosmetic fixes and rebase
Changes since v4:
* use a file abstraction (handle) to wrap inode, dentry, path and file
structs
* remove bpf_landlock_cmp_fs_beneath()
* rename the BPF helper and move it to kernel/bpf/
* tighten helpers accessible by a Landlock rule
Changes since v3:
* remove bpf_landlock_cmp_fs_prop() (suggested by Alexei Starovoitov)
* add hooks dealing with struct inode and struct path pointers:
inode_permission and inode_getattr
* add abstraction over eBPF helper arguments thanks to wrapping structs
* add bpf_landlock_get_fs_mode() helper to check file type and mode
* merge WARN_ON() (suggested by Kees Cook)
* fix and update bpf_helpers.h
* use BPF_CALL_* for eBPF helpers (suggested by Alexei Starovoitov)
* make handle arraymap safe (RCU) and remove buggy synchronize_rcu()
* factor out the arraymay walk
* use size_t to index array (suggested by Jann Horn)
Changes since v2:
* add MNT_INTERNAL check to only add file handle from user-visible FS
(e.g. no anonymous inode)
* replace struct file* with struct path* in map_landlock_handle
* add BPF protos
* fix bpf_landlock_cmp_fs_prop_with_struct_file()
---
include/linux/bpf.h | 9 +
include/linux/bpf_types.h | 3 +
include/uapi/linux/bpf.h | 12 +-
kernel/bpf/Makefile | 3 +
kernel/bpf/core.c | 2 +
kernel/bpf/inodemap.c | 315 +++++++++++++++++++++++++++++++++
kernel/bpf/syscall.c | 27 ++-
kernel/bpf/verifier.c | 14 ++
tools/include/uapi/linux/bpf.h | 12 +-
tools/lib/bpf/libbpf_probes.c | 1 +
10 files changed, 395 insertions(+), 3 deletions(-)
create mode 100644 kernel/bpf/inodemap.c
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index da167d3afecc..cc72ec18f0f6 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -208,6 +208,8 @@ enum bpf_arg_type {
ARG_PTR_TO_INT, /* pointer to int */
ARG_PTR_TO_LONG, /* pointer to long */
ARG_PTR_TO_SOCKET, /* pointer to bpf_sock (fullsock) */
+
+ ARG_PTR_TO_INODE, /* pointer to a struct inode */
};
/* type of values returned from helper functions */
@@ -278,6 +280,7 @@ enum bpf_reg_type {
PTR_TO_TCP_SOCK_OR_NULL, /* reg points to struct tcp_sock or NULL */
PTR_TO_TP_BUFFER, /* reg points to a writable raw tp's buffer */
PTR_TO_XDP_SOCK, /* reg points to struct xdp_sock */
+ PTR_TO_INODE, /* reg points to struct inode */
};
/* The information passed from prog-specific *_is_valid_access
@@ -485,6 +488,7 @@ struct bpf_event_entry {
struct rcu_head rcu;
};
+
bool bpf_prog_array_compatible(struct bpf_array *array, const struct bpf_prog *fp);
int bpf_prog_calc_tag(struct bpf_prog *fp);
@@ -689,6 +693,10 @@ int bpf_fd_array_map_lookup_elem(struct bpf_map *map, void *key, u32 *value);
int bpf_fd_htab_map_update_elem(struct bpf_map *map, struct file *map_file,
void *key, void *value, u64 map_flags);
int bpf_fd_htab_map_lookup_elem(struct bpf_map *map, void *key, u32 *value);
+int bpf_inode_map_update_elem(struct bpf_map *map, int *key, u64 *value,
+ u64 flags);
+int bpf_inode_map_lookup_elem(struct bpf_map *map, int *key, u64 *value);
+int bpf_inode_map_delete_elem(struct bpf_map *map, int *key);
int bpf_get_file_flag(int flags);
int bpf_check_uarg_tail_zero(void __user *uaddr, size_t expected_size,
@@ -1059,6 +1067,7 @@ extern const struct bpf_func_proto bpf_spin_unlock_proto;
extern const struct bpf_func_proto bpf_get_local_storage_proto;
extern const struct bpf_func_proto bpf_strtol_proto;
extern const struct bpf_func_proto bpf_strtoul_proto;
+extern const struct bpf_func_proto bpf_inode_map_lookup_proto;
/* Shared helpers among cBPF and eBPF. */
void bpf_user_rnd_init_once(void);
diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h
index dee8b82e31b1..9e385473b57a 100644
--- a/include/linux/bpf_types.h
+++ b/include/linux/bpf_types.h
@@ -79,3 +79,6 @@ BPF_MAP_TYPE(BPF_MAP_TYPE_REUSEPORT_SOCKARRAY, reuseport_array_ops)
#endif
BPF_MAP_TYPE(BPF_MAP_TYPE_QUEUE, queue_map_ops)
BPF_MAP_TYPE(BPF_MAP_TYPE_STACK, stack_map_ops)
+#ifdef CONFIG_SECURITY_LANDLOCK
+BPF_MAP_TYPE(BPF_MAP_TYPE_INODE, inode_ops)
+#endif
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 50145d448bc3..08ff720835ba 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -134,6 +134,7 @@ enum bpf_map_type {
BPF_MAP_TYPE_QUEUE,
BPF_MAP_TYPE_STACK,
BPF_MAP_TYPE_SK_STORAGE,
+ BPF_MAP_TYPE_INODE,
};
/* Note that tracing related programs such as
@@ -2716,6 +2717,14 @@ union bpf_attr {
* **-EPERM** if no permission to send the *sig*.
*
* **-EAGAIN** if bpf program can try again.
+ *
+ * u64 bpf_inode_map_lookup(map, key)
+ * Description
+ * Perform a lookup in *map* for an entry associated to an inode
+ * *key*.
+ * Return
+ * Map value associated to *key*, or **NULL** if no entry was
+ * found.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -2827,7 +2836,8 @@ union bpf_attr {
FN(strtoul), \
FN(sk_storage_get), \
FN(sk_storage_delete), \
- FN(send_signal),
+ FN(send_signal), \
+ FN(inode_map_lookup),
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call
diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile
index 29d781061cd5..e6fe613b3105 100644
--- a/kernel/bpf/Makefile
+++ b/kernel/bpf/Makefile
@@ -22,3 +22,6 @@ obj-$(CONFIG_CGROUP_BPF) += cgroup.o
ifeq ($(CONFIG_INET),y)
obj-$(CONFIG_BPF_SYSCALL) += reuseport_array.o
endif
+ifeq ($(CONFIG_SECURITY_LANDLOCK),y)
+obj-$(CONFIG_BPF_SYSCALL) += inodemap.o
+endif
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 8ad392e52328..3cf5d16a8496 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -2032,6 +2032,8 @@ const struct bpf_func_proto bpf_get_current_comm_proto __weak;
const struct bpf_func_proto bpf_get_current_cgroup_id_proto __weak;
const struct bpf_func_proto bpf_get_local_storage_proto __weak;
+const struct bpf_func_proto bpf_inode_map_update_proto __weak;
+
const struct bpf_func_proto * __weak bpf_get_trace_printk_proto(void)
{
return NULL;
diff --git a/kernel/bpf/inodemap.c b/kernel/bpf/inodemap.c
new file mode 100644
index 000000000000..fcad0de51557
--- /dev/null
+++ b/kernel/bpf/inodemap.c
@@ -0,0 +1,315 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * inode map for Landlock
+ *
+ * Copyright © 2017-2019 Mickaël Salaün <mic@digikod.net>
+ * Copyright © 2019 ANSSI
+ */
+
+#include <asm/resource.h> /* RLIMIT_NOFILE */
+#include <linux/bpf.h>
+#include <linux/err.h>
+#include <linux/file.h> /* fput() */
+#include <linux/filter.h> /* BPF_CALL_2() */
+#include <linux/fs.h> /* struct file */
+#include <linux/mm.h>
+#include <linux/mount.h> /* MNT_INTERNAL */
+#include <linux/path.h> /* struct path */
+#include <linux/sched/signal.h> /* rlimit() */
+#include <linux/security.h>
+#include <linux/slab.h>
+
+struct inode_elem {
+ struct inode *inode;
+ u64 value;
+};
+
+struct inode_array {
+ struct bpf_map map;
+ size_t nb_entries;
+ struct inode_elem elems[0];
+};
+
+/* must call iput(inode) after this call */
+static struct inode *inode_from_fd(int ufd, bool check_access)
+{
+ struct inode *ret;
+ struct fd f;
+ int deny;
+
+ f = fdget(ufd);
+ if (unlikely(!f.file || !file_inode(f.file))) {
+ ret = ERR_PTR(-EBADF);
+ goto put_fd;
+ }
+ /* TODO: add this check when called from an eBPF program too (already
+ * checked by the LSM parent hooks anyway) */
+ if (unlikely(IS_PRIVATE(file_inode(f.file)))) {
+ ret = ERR_PTR(-EINVAL);
+ goto put_fd;
+ }
+ /* check if the FD is tied to a mount point */
+ /* TODO: add this check when called from an eBPF program too */
+ if (unlikely(!f.file->f_path.mnt || f.file->f_path.mnt->mnt_flags &
+ MNT_INTERNAL)) {
+ ret = ERR_PTR(-EINVAL);
+ goto put_fd;
+ }
+ if (check_access) {
+ /*
+ * need to be allowed to access attributes from this file to
+ * then be able to compare an inode to this entry
+ */
+ deny = security_inode_getattr(&f.file->f_path);
+ if (deny) {
+ ret = ERR_PTR(deny);
+ goto put_fd;
+ }
+ }
+ ret = file_inode(f.file);
+ ihold(ret);
+
+put_fd:
+ fdput(f);
+ return ret;
+}
+
+/* (never) called from eBPF program */
+static int fake_map_delete_elem(struct bpf_map *map, void *key)
+{
+ WARN_ON(1);
+ return -EINVAL;
+}
+
+/* called from syscall */
+static int sys_inode_map_delete_elem(struct bpf_map *map, struct inode *key)
+{
+ struct inode_array *array = container_of(map, struct inode_array, map);
+ struct inode *inode;
+ int i;
+
+ WARN_ON_ONCE(!rcu_read_lock_held());
+ for (i = 0; i < array->map.max_entries; i++) {
+ if (array->elems[i].inode == key) {
+ inode = xchg(&array->elems[i].inode, NULL);
+ array->nb_entries--;
+ iput(inode);
+ return 0;
+ }
+ }
+ return -ENOENT;
+}
+
+/* called from syscall */
+int bpf_inode_map_delete_elem(struct bpf_map *map, int *key)
+{
+ struct inode *inode;
+ int err;
+
+ inode = inode_from_fd(*key, false);
+ if (IS_ERR(inode))
+ return PTR_ERR(inode);
+ err = sys_inode_map_delete_elem(map, inode);
+ iput(inode);
+ return err;
+}
+
+static void inode_map_free(struct bpf_map *map)
+{
+ struct inode_array *array = container_of(map, struct inode_array, map);
+ int i;
+
+ synchronize_rcu();
+ for (i = 0; i < array->map.max_entries; i++)
+ iput(array->elems[i].inode);
+ bpf_map_area_free(array);
+}
+
+static struct bpf_map *inode_map_alloc(union bpf_attr *attr)
+{
+ int numa_node = bpf_map_attr_numa_node(attr);
+ struct inode_array *array;
+ u64 array_size;
+
+ /* only allow root to create this type of map (for now), should be
+ * removed when Landlock will be usable by unprivileged users */
+ if (!capable(CAP_SYS_ADMIN))
+ return ERR_PTR(-EPERM);
+
+ /* the key is a file descriptor and the value must be 64-bits (for
+ * now) */
+ if (attr->max_entries == 0 || attr->key_size != sizeof(u32) ||
+ attr->value_size != FIELD_SIZEOF(struct inode_elem, value) ||
+ attr->map_flags & ~(BPF_F_RDONLY | BPF_F_WRONLY) ||
+ numa_node != NUMA_NO_NODE)
+ return ERR_PTR(-EINVAL);
+
+ if (attr->value_size > KMALLOC_MAX_SIZE)
+ /* if value_size is bigger, the user space won't be able to
+ * access the elements.
+ */
+ return ERR_PTR(-E2BIG);
+
+ /*
+ * Limit number of entries in an inode map to the maximum number of
+ * open files for the current process. The maximum number of file
+ * references (including all inode maps) for a process is then
+ * (RLIMIT_NOFILE - 1) * RLIMIT_NOFILE. If the process' RLIMIT_NOFILE
+ * is 0, then any entry update is forbidden.
+ *
+ * An eBPF program can inherit all the inode map FD. The worse case is
+ * to fill a bunch of arraymaps, create an eBPF program, close the
+ * inode map FDs, and start again. The maximum number of inode map
+ * entries can then be close to RLIMIT_NOFILE^3.
+ */
+ if (attr->max_entries > rlimit(RLIMIT_NOFILE))
+ return ERR_PTR(-EMFILE);
+
+ array_size = sizeof(*array);
+ array_size += (u64) attr->max_entries * sizeof(struct inode_elem);
+
+ /* make sure there is no u32 overflow later in round_up() */
+ if (array_size >= U32_MAX - PAGE_SIZE)
+ return ERR_PTR(-ENOMEM);
+
+ /* allocate all map elements and zero-initialize them */
+ array = bpf_map_area_alloc(array_size, numa_node);
+ if (!array)
+ return ERR_PTR(-ENOMEM);
+
+ /* copy mandatory map attributes */
+ bpf_map_init_from_attr(&array->map, attr);
+ array->map.memory.pages = round_up(array_size, PAGE_SIZE) >> PAGE_SHIFT;
+
+ return &array->map;
+}
+
+/* (never) called from eBPF program */
+static void *fake_map_lookup_elem(struct bpf_map *map, void *key)
+{
+ WARN_ON(1);
+ return ERR_PTR(-EINVAL);
+}
+
+/* called from syscall (wrapped) and eBPF program */
+static u64 inode_map_lookup_elem(struct bpf_map *map, struct inode *key)
+{
+ struct inode_array *array = container_of(map, struct inode_array, map);
+ size_t i;
+ u64 ret = 0;
+
+ WARN_ON_ONCE(!rcu_read_lock_held());
+ /* TODO: use rbtree to switch to O(log n) */
+ for (i = 0; i < array->map.max_entries; i++) {
+ if (array->elems[i].inode == key) {
+ ret = array->elems[i].value;
+ break;
+ }
+ }
+ return ret;
+}
+
+/*
+ * The key is a FD when called from a syscall, but an inode pointer when called
+ * from an eBPF program.
+ */
+
+/* called from syscall */
+int bpf_inode_map_lookup_elem(struct bpf_map *map, int *key, u64 *value)
+{
+ struct inode *inode;
+
+ inode = inode_from_fd(*key, false);
+ if (IS_ERR(inode))
+ return PTR_ERR(inode);
+ *value = inode_map_lookup_elem(map, inode);
+ iput(inode);
+ if (!value)
+ return -ENOENT;
+ return 0;
+}
+
+/* (never) called from eBPF program */
+static int fake_map_update_elem(struct bpf_map *map, void *key, void *value,
+ u64 flags)
+{
+ WARN_ON(1);
+ /* do not leak an inode accessed by a Landlock program */
+ return -EINVAL;
+}
+
+/* called from syscall */
+static int sys_inode_map_update_elem(struct bpf_map *map, struct inode *key,
+ u64 *value, u64 flags)
+{
+ struct inode_array *array = container_of(map, struct inode_array, map);
+ size_t i;
+
+ if (unlikely(flags != BPF_ANY))
+ return -EINVAL;
+
+ if (unlikely(array->nb_entries >= array->map.max_entries))
+ /* all elements were pre-allocated, cannot insert a new one */
+ return -E2BIG;
+
+ for (i = 0; i < array->map.max_entries; i++) {
+ if (!array->elems[i].inode) {
+ /* the inode (key) is already grabbed by the caller */
+ ihold(key);
+ array->elems[i].inode = key;
+ array->elems[i].value = *value;
+ array->nb_entries++;
+ return 0;
+ }
+ }
+ WARN_ON(1);
+ return -ENOENT;
+}
+
+/* called from syscall */
+int bpf_inode_map_update_elem(struct bpf_map *map, int *key, u64 *value,
+ u64 flags)
+{
+ struct inode *inode;
+ int err;
+
+ WARN_ON_ONCE(!rcu_read_lock_held());
+ inode = inode_from_fd(*key, true);
+ if (IS_ERR(inode))
+ return PTR_ERR(inode);
+ err = sys_inode_map_update_elem(map, inode, value, flags);
+ iput(inode);
+ return err;
+}
+
+/* called from syscall or (never) from eBPF program */
+static int fake_map_get_next_key(struct bpf_map *map, void *key,
+ void *next_key)
+{
+ /* do not leak a file descriptor */
+ return -EINVAL;
+}
+
+/* void map for eBPF program */
+const struct bpf_map_ops inode_ops = {
+ .map_alloc = inode_map_alloc,
+ .map_free = inode_map_free,
+ .map_get_next_key = fake_map_get_next_key,
+ .map_lookup_elem = fake_map_lookup_elem,
+ .map_delete_elem = fake_map_delete_elem,
+ .map_update_elem = fake_map_update_elem,
+};
+
+BPF_CALL_2(bpf_inode_map_lookup, struct bpf_map *, map, void *, key)
+{
+ WARN_ON_ONCE(!rcu_read_lock_held());
+ return inode_map_lookup_elem(map, key);
+}
+
+const struct bpf_func_proto bpf_inode_map_lookup_proto = {
+ .func = bpf_inode_map_lookup,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_CONST_MAP_PTR,
+ .arg2_type = ARG_PTR_TO_INODE,
+};
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 7dd3376904d4..ba2a09a7f813 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -720,6 +720,22 @@ static void *__bpf_copy_key(void __user *ukey, u64 key_size)
return NULL;
}
+int __weak bpf_inode_map_update_elem(struct bpf_map *map, int *key,
+ u64 *value, u64 flags)
+{
+ return -ENOTSUPP;
+}
+
+int __weak bpf_inode_map_lookup_elem(struct bpf_map *map, int *key, u64 *value)
+{
+ return -ENOTSUPP;
+}
+
+int __weak bpf_inode_map_delete_elem(struct bpf_map *map, int *key)
+{
+ return -ENOTSUPP;
+}
+
/* last field in 'union bpf_attr' used by this command */
#define BPF_MAP_LOOKUP_ELEM_LAST_FIELD flags
@@ -801,6 +817,8 @@ static int map_lookup_elem(union bpf_attr *attr)
} else if (map->map_type == BPF_MAP_TYPE_QUEUE ||
map->map_type == BPF_MAP_TYPE_STACK) {
err = map->ops->map_peek_elem(map, value);
+ } else if (map->map_type == BPF_MAP_TYPE_INODE) {
+ err = bpf_inode_map_lookup_elem(map, key, value);
} else {
rcu_read_lock();
if (map->ops->map_lookup_elem_sys_only)
@@ -951,6 +969,10 @@ static int map_update_elem(union bpf_attr *attr)
} else if (map->map_type == BPF_MAP_TYPE_QUEUE ||
map->map_type == BPF_MAP_TYPE_STACK) {
err = map->ops->map_push_elem(map, value, attr->flags);
+ } else if (map->map_type == BPF_MAP_TYPE_INODE) {
+ rcu_read_lock();
+ err = bpf_inode_map_update_elem(map, key, value, attr->flags);
+ rcu_read_unlock();
} else {
rcu_read_lock();
err = map->ops->map_update_elem(map, key, value, attr->flags);
@@ -1006,7 +1028,10 @@ static int map_delete_elem(union bpf_attr *attr)
preempt_disable();
__this_cpu_inc(bpf_prog_active);
rcu_read_lock();
- err = map->ops->map_delete_elem(map, key);
+ if (map->map_type == BPF_MAP_TYPE_INODE)
+ err = bpf_inode_map_delete_elem(map, key);
+ else
+ err = map->ops->map_delete_elem(map, key);
rcu_read_unlock();
__this_cpu_dec(bpf_prog_active);
preempt_enable();
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 930260683d0a..ce3cd7fd8882 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -400,6 +400,7 @@ static const char * const reg_type_str[] = {
[PTR_TO_TCP_SOCK_OR_NULL] = "tcp_sock_or_null",
[PTR_TO_TP_BUFFER] = "tp_buffer",
[PTR_TO_XDP_SOCK] = "xdp_sock",
+ [PTR_TO_INODE] = "inode",
};
static char slot_type_char[] = {
@@ -1801,6 +1802,7 @@ static bool is_spillable_regtype(enum bpf_reg_type type)
case PTR_TO_TCP_SOCK:
case PTR_TO_TCP_SOCK_OR_NULL:
case PTR_TO_XDP_SOCK:
+ case PTR_TO_INODE:
return true;
default:
return false;
@@ -3254,6 +3256,10 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 regno,
verbose(env, "verifier internal error\n");
return -EFAULT;
}
+ } else if (arg_type == ARG_PTR_TO_INODE) {
+ expected_type = PTR_TO_INODE;
+ if (type != expected_type)
+ goto err_type;
} else if (arg_type_is_mem_ptr(arg_type)) {
expected_type = PTR_TO_STACK;
/* One exception here. In case function allows for NULL to be
@@ -3462,6 +3468,10 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
func_id != BPF_FUNC_sk_storage_delete)
goto error;
break;
+ case BPF_MAP_TYPE_INODE:
+ if (func_id != BPF_FUNC_inode_map_lookup)
+ goto error;
+ break;
default:
break;
}
@@ -3530,6 +3540,10 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
if (map->map_type != BPF_MAP_TYPE_SK_STORAGE)
goto error;
break;
+ case BPF_FUNC_inode_map_lookup:
+ if (map->map_type != BPF_MAP_TYPE_INODE)
+ goto error;
+ break;
default:
break;
}
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 50145d448bc3..08ff720835ba 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -134,6 +134,7 @@ enum bpf_map_type {
BPF_MAP_TYPE_QUEUE,
BPF_MAP_TYPE_STACK,
BPF_MAP_TYPE_SK_STORAGE,
+ BPF_MAP_TYPE_INODE,
};
/* Note that tracing related programs such as
@@ -2716,6 +2717,14 @@ union bpf_attr {
* **-EPERM** if no permission to send the *sig*.
*
* **-EAGAIN** if bpf program can try again.
+ *
+ * u64 bpf_inode_map_lookup(map, key)
+ * Description
+ * Perform a lookup in *map* for an entry associated to an inode
+ * *key*.
+ * Return
+ * Map value associated to *key*, or **NULL** if no entry was
+ * found.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -2827,7 +2836,8 @@ union bpf_attr {
FN(strtoul), \
FN(sk_storage_get), \
FN(sk_storage_delete), \
- FN(send_signal),
+ FN(send_signal), \
+ FN(inode_map_lookup),
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call
diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c
index f4f34cb8869a..000319a95bfb 100644
--- a/tools/lib/bpf/libbpf_probes.c
+++ b/tools/lib/bpf/libbpf_probes.c
@@ -249,6 +249,7 @@ bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex)
case BPF_MAP_TYPE_XSKMAP:
case BPF_MAP_TYPE_SOCKHASH:
case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY:
+ case BPF_MAP_TYPE_INODE:
default:
break;
}
--
2.20.1
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