* [PATCH 0/5] rust: lsm: introduce safe Rust abstractions for the LSM framework
From: Jamie Lindsey @ 2026-03-11 4:56 UTC (permalink / raw)
To: rust-for-linux, linux-security-module
Cc: ojeda, paul, aliceryhl, jmorris, serge, jamie
This series introduces the first safe Rust abstractions for the Linux
Security Module (LSM) framework. It allows a complete, policy-enforcing
LSM to be written entirely in Rust with no C boilerplate required from
the LSM author.
--- Motivation ---
The LSM framework is a natural target for Rust: hook registration is
unsafe by nature (raw function pointers, C ABI, __randomize_layout on
the hook list struct), and the trait system can enforce correct
implementation at compile time.
--- Design ---
The abstraction is trait-based:
impl kernel::lsm::Hooks for MyLsm {
fn file_open(file: &File) -> Result { ... }
}
kernel::define_lsm!(MyLsm, "my_lsm\0", bindings::LSM_ID_UNDEF as u64);
The define_lsm! macro generates all the plumbing: the lsm_id, the hook
array, the __init function that calls security_add_hooks(), and the
lsm_info descriptor placed in .lsm_info.init so that security_init()
discovers it at boot.
Hook implementations receive safe Rust wrappers (&File, &Task) and
return kernel::error::Result. The C-callable adapter functions are
monomorphised per LSM type -- no vtable, no runtime dispatch.
--- Implementation notes for reviewers ---
static mut __LSM_HOOKS:
The hook array is static mut because it is written exactly once by
__lsm_init() in the single-threaded boot context, before
security_add_hooks() copies the entries into the static-call table.
No access occurs after that point. UnsafeCell or a lock would add
overhead with no safety benefit in this strictly init-only path.
unsafe impl Sync on LsmId / LsmInfo:
Both types are #[repr(transparent)] wrappers around lsm_id / lsm_info,
which contain *const c_char pointers to 'static NUL-terminated string
literals that are never mutated. The Sync impl is sound for the same
reason that &'static str is Sync.
MaybeUninit hook array:
security_hook_list carries __randomize_layout. Rust code cannot safely
initialise it by field name (the field order after randomisation differs
from what bindgen sees). The array is left MaybeUninit and filled at
runtime by C shims that call LSM_HOOK_INIT() -- the macro the kernel
already uses for this purpose in C LSMs.
Function pointer types:
All three hook signatures were verified against union security_list_options
generated from lsm_hook_defs.h in this exact tree. file_open:
int(*)(struct file *); task_alloc: int(*)(struct task_struct *, u64)
(u64, not unsigned long -- tree-specific); task_free:
void(*)(struct task_struct *). All match the C shim parameters exactly.
checkpatch note:
checkpatch reports "Non-standard signature: Assisted-by" and
"Unrecognized email address: Claude:claude-sonnet-4-6". The
Assisted-by tag and its format are defined in
Documentation/process/coding-assistants.rst; checkpatch has not yet
been updated to recognise it. This is a false positive.
--- Limitations (v1) ---
- Three hooks: file_open, task_alloc, task_free. Additional hooks will
be added in follow-up patches as safe Rust wrappers for their argument
types are contributed upstream.
- At most one Rust LSM per kernel build (unique static symbol names
require a proc-macro; planned for v2).
- No security blob support (SecurityBlob<T> planned for v2).
--- Testing ---
Compiled and boot-tested on Linux 7.0-rc2
(commit 4ae12d8bd9a8 "Merge tag 'kbuild-fixes-7.0-2' of
git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux").
Boot verified: with lsm=rust_lsm_sample on the kernel command line,
/sys/kernel/security/lsm reports "capability,rust_lsm_sample" and
task_alloc hook invocations appear in dmesg.
--- Patch overview ---
[1/5] rust: bindings: include lsm_hooks.h -- expose LSM types to bindgen
[2/5] rust: helpers: C shims for LSM_HOOK_INIT and security_add_hooks
[3/5] rust: kernel: lsm -- Hooks trait, Adapter<T>, define_lsm! macro
[4/5] security: rust_lsm_sample -- reference implementation and boot test
[5/5] Documentation: rust: lsm abstraction developer guide; MAINTAINERS
Jamie Lindsey (5):
rust: bindings: include lsm_hooks.h to expose LSM types to bindgen
rust: helpers: add C shims for LSM hook initialisation
rust: kernel: add LSM abstraction layer
security: add Rust LSM sample (CONFIG_SECURITY_RUST_LSM)
Documentation: rust: add LSM abstraction guide; update MAINTAINERS
Documentation/rust/index.rst | 1 +
Documentation/rust/lsm.rst | 246 ++++++++++++++++++++++++++
MAINTAINERS | 9 +
rust/bindings/bindings_helper.h | 1 +
rust/helpers/helpers.c | 1 +
rust/helpers/lsm.c | 49 ++++++
rust/kernel/lib.rs | 2 +
rust/kernel/lsm.rs | 295 ++++++++++++++++++++++++++++++++
security/Kconfig | 2 +
security/Makefile | 1 +
security/rust_lsm/Kconfig | 14 ++
security/rust_lsm/Makefile | 2 +
security/rust_lsm/rust_lsm.rs | 66 +++++++
13 files changed, 689 insertions(+)
create mode 100644 Documentation/rust/lsm.rst
create mode 100644 rust/helpers/lsm.c
create mode 100644 rust/kernel/lsm.rs
create mode 100644 security/rust_lsm/Kconfig
create mode 100644 security/rust_lsm/Makefile
create mode 100644 security/rust_lsm/rust_lsm.rs
--
2.53.0
^ permalink raw reply
* Re: [PATCH v5 2/9] landlock: Control pathname UNIX domain socket resolution by path
From: Kuniyuki Iwashima @ 2026-03-11 4:46 UTC (permalink / raw)
To: Mickaël Salaün
Cc: Günther Noack, Eric Dumazet, Paolo Abeni, Willem de Bruijn,
Sebastian Andrzej Siewior, Jason Xing, John Johansen,
Tingmao Wang, Justin Suess, Jann Horn, linux-security-module,
Samasth Norway Ananda, Matthieu Buffet, Mikhail Ivanov,
konstantin.meskhidze, Demi Marie Obenour, Alyssa Ross,
Tahera Fahimi, netdev
In-Reply-To: <20260308.AiYoh5KooBei@digikod.net>
On Sun, Mar 8, 2026 at 1:18 AM Mickaël Salaün <mic@digikod.net> wrote:
>
> On Fri, Feb 20, 2026 at 03:33:28PM +0100, Günther Noack wrote:
> > +netdev, we could use some advice on the locking approach in af_unix (see below)
> >
> > On Wed, Feb 18, 2026 at 10:37:14AM +0100, Mickaël Salaün wrote:
> > > On Sun, Feb 15, 2026 at 11:51:50AM +0100, Günther Noack wrote:
> > > > diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h
> > > > index f88fa1f68b77..3a8fc3af0d64 100644
> > > > --- a/include/uapi/linux/landlock.h
> > > > +++ b/include/uapi/linux/landlock.h
> > > > @@ -248,6 +248,15 @@ struct landlock_net_port_attr {
> > > > *
> > > > * This access right is available since the fifth version of the Landlock
> > > > * ABI.
> > > > + * - %LANDLOCK_ACCESS_FS_RESOLVE_UNIX: Look up pathname UNIX domain sockets
> > > > + * (:manpage:`unix(7)`). On UNIX domain sockets, this restricts both calls to
> > > > + * :manpage:`connect(2)` as well as calls to :manpage:`sendmsg(2)` with an
> > > > + * explicit recipient address.
> > > > + *
> > > > + * This access right only applies to connections to UNIX server sockets which
> > > > + * were created outside of the newly created Landlock domain (e.g. from within
> > > > + * a parent domain or from an unrestricted process). Newly created UNIX
> > > > + * servers within the same Landlock domain continue to be accessible.
> > >
> > > It might help to add a reference to the explicit scope mechanism.
> > >
> > > Please squash patch 9/9 into this one and also add a reference here to
> > > the rationale described in security/landlock.rst
> >
> > Sounds good, will do.
> >
> >
> > > > +static void unmask_scoped_access(const struct landlock_ruleset *const client,
> > > > + const struct landlock_ruleset *const server,
> > > > + struct layer_access_masks *const masks,
> > > > + const access_mask_t access)
> > >
> > > This helper should be moved to task.c and factored out with
> > > domain_is_scoped(). This should be a dedicated patch.
> >
> > (already discussed in another follow-up mail)
> >
> >
> > > > +static int hook_unix_find(const struct path *const path, struct sock *other,
> > > > + int flags)
> > > > +{
> > > > + const struct landlock_ruleset *dom_other;
> > > > + const struct landlock_cred_security *subject;
> > > > + struct layer_access_masks layer_masks;
> > > > + struct landlock_request request = {};
> > > > + static const struct access_masks fs_resolve_unix = {
> > > > + .fs = LANDLOCK_ACCESS_FS_RESOLVE_UNIX,
> > > > + };
> > > > +
> > > > + /* Lookup for the purpose of saving coredumps is OK. */
> > > > + if (unlikely(flags & SOCK_COREDUMP))
> > > > + return 0;
> > > > +
> > > > + /* Access to the same (or a lower) domain is always allowed. */
> > > > + subject = landlock_get_applicable_subject(current_cred(),
> > > > + fs_resolve_unix, NULL);
> > > > +
> > > > + if (!subject)
> > > > + return 0;
> > > > +
> > > > + if (!landlock_init_layer_masks(subject->domain, fs_resolve_unix.fs,
> > > > + &layer_masks, LANDLOCK_KEY_INODE))
> > > > + return 0;
> > > > +
> > > > + /* Checks the layers in which we are connecting within the same domain. */
> > > > + dom_other = landlock_cred(other->sk_socket->file->f_cred)->domain;
> > >
> > > We need to call unix_state_lock(other) before reading it, and check for
> > > SOCK_DEAD, and check sk_socket before dereferencing it. Indeed,
> > > the socket can be make orphan (see unix_dgram_sendmsg and
> > > unix_stream_connect). I *think* a socket cannot be "resurrected" or
> > > recycled once dead, so we may assume there is no race condition wrt
> > > dom_other, but please double check. This lockless call should be made
> > > clear in the LSM hook. It's OK to not lock the socket before
> > > security_unix_find() (1) because no LSM might implement and (2) they
> > > might not need to lock the socket (e.g. if the caller is not sandboxed).
> > >
> > > The updated code should look something like this:
> > >
> > > unix_state_unlock(other);
>
> unix_state_lock(other) of course...
>
> > > if (unlikely(sock_flag(other, SOCK_DEAD) || !other->sk_socket)) {
> > > unix_state_unlock(other);
> > > return 0;
> > > }
> > >
> > > dom_other = landlock_cred(other->sk_socket->file->f_cred)->domain;
> > > unix_state_unlock(other);
> >
> > Thank you for spotting the locking concern!
> >
> > @anyone from netdev, could you please advise on the correct locking
> > approach here?
> >
> > * Do we need ot check SOCK_DEAD?
It depends ? But I don't see your full patch and have no
idea how it will be used.
> >
> > You are saying that we need to do that, but it's not clear to me
> > why.
> >
> > If you look at the places where unix_find_other() is called in
> > af_unix.c, then you'll find that all of them check for SOCK_DEAD and
> > then restart from unix_find_other() if they do actually discover
> > that the socket is dead.
Note all callers of unix_find_other() later locks the other
and double check SOCK_DEAD.
The same check in unix_find_other() is to avoid unnecessary
locking in case the socket is dying.
> > I think that this is catching this race
> > condition scenario:
> >
> > * a server socket exists and is alive
> > * A client connects: af_unix.c's unix_stream_connect() calls
> > unix_find_other() and finds the server socket...
> > * (Concurrently): The server closes the socket and enters
> > unix_release_sock(). This function:
> > 1. disassociates the server sock from the named socket inode
> > number in the hash table (=> future unix_find_other() calls
> > will fail).
> > 2. calls sock_orphan(), which sets SOCK_DEAD.
> > * ...(client connection resuming): unix_stream_connect() continues,
> > grabs the unix_state_lock(), which apparently protects everything
> > here, checks that the socket is not dead - and discovers that it
> > IS suddenly dead. This was not supposed to happen. The code
> > recovers from that by retrying everything starting with the
> > unix_find_other() call. From unix_release_sock(), we know that
> > the inode is not associated with the sock any more -- so the
> > unix_find_socket_by_inode() call should be failing on the next
> > attempt.
> >
> > (This works with unix_dgram_connect() and unix_dgram_sendmsg() as
> > well.)
> >
> > The comments next to the SOCK_DEAD checks are also suggesting this.
> >
> > * What lock to use
> >
> > I am having trouble reasoning about what lock is used for what in
> > this code.
>
> It's not clear to me neither, and it looks like it's not consistent
> across protocols.
>
> >
> > Is it possible that the lock protecting ->sk_socket is the
> > ->sk_callback_lock, not the unix_state_lock()?
Yes, but unix_state_lock() is better.
BPF SOCKMAP is the major user of sk_callback_lock.
> > The only callers to
> > sk_set_socket are either sock_orphan/sock_graft (both grabbing
> > sk_callback_lock), or they are creating new struct sock objects that
> > they own exclusively, and don't need locks yet.
> >
> > Admittedly, in af_unix.c, sock_orphan() and sock_graft() only get
> > called in contexts where the unix_state_lock() is held, so it would
> > probably work as well to lock that, but it is maybe a more
> > fine-grained approach to use sk_callback_lock?
> >
> >
> > So... how about a scheme where we only check for ->sk_socket not being
> > NULL:
> >
> > read_lock_bh(&other->sk_callback_lock);
> > struct sock *other_sk = other->sk_socket;
> > if (!other_sk) {
> > read_unlock_bh(&other->sk_callback_lock);
> > return 0;
> > }
> > /* XXX double check whether we need a lock here too */
> > struct file *file = other_sk->file;
> > if (!other_file) {
> > read_unlock_bh(&other->sk_callback_lock);
> > return 0;
> > }
> > read_unlock_bh(&other->sk_callback_lock);
> >
> > If this fails, that would in my understanding also be because the
> > socket has died after the path lookup. We'd then return 0 (success),
> > because we know that the surrounding SOCK_DEAD logic will repeat
> > everything starting from the path lookup operation (this time likely
> > failing with ECONNREFUSED, but maybe also with a success, if another
> > server process was quick enough).
> >
> > Does this sound reasonable?
>
> Actually, since commit 983512f3a87f ("net: Drop the lock in
> skb_may_tx_timestamp()"), we can just use RCU + READ_ONCE(sk_socket) +
> READ_ONCE(file). The socket and file should only be freed after the RCU
> grace periode. As a safeguard, this commit should be a Depends-on.
Note this commit is for the networking fast path (interrupt context),
where we want to avoid unnecessary locking as much as possible.
AF_UNIX works in the process context only and does not
need to follow the pattern.
>
> However, it is safer to return -ECONNREFULED when sk_socket or file are
> NULL.
>
> I would be good to hear from netdev folks though.
>
> TIL, there is an LSM hook for sock_graft().
>
> > –Günther
> >
^ permalink raw reply
* Re: [PATCH 56/61] clk: Prefer IS_ERR_OR_NULL over manual NULL check
From: Chen-Yu Tsai @ 2026-03-11 2:07 UTC (permalink / raw)
To: Philipp Hahn
Cc: amd-gfx, apparmor, bpf, ceph-devel, cocci, dm-devel, dri-devel,
gfs2, intel-gfx, intel-wired-lan, iommu, kvm, linux-arm-kernel,
linux-block, linux-bluetooth, linux-btrfs, linux-cifs, linux-clk,
linux-erofs, linux-ext4, linux-fsdevel, linux-gpio, linux-hyperv,
linux-input, linux-kernel, linux-leds, linux-media, linux-mips,
linux-mm, linux-modules, linux-mtd, linux-nfs, linux-omap,
linux-phy, linux-pm, linux-rockchip, linux-s390, linux-scsi,
linux-sctp, linux-security-module, linux-sh, linux-sound,
linux-stm32, linux-trace-kernel, linux-usb, linux-wireless,
netdev, ntfs3, samba-technical, sched-ext, target-devel,
tipc-discussion, v9fs, Michael Turquette, Stephen Boyd,
Daniel Lezcano, Thomas Gleixner
In-Reply-To: <20260310-b4-is_err_or_null-v1-56-bd63b656022d@avm.de>
On Tue, Mar 10, 2026 at 9:57 PM Philipp Hahn <phahn-oss@avm.de> wrote:
>
> Prefer using IS_ERR_OR_NULL() over using IS_ERR() and a manual NULL
> check.
>
> Semantich change: Previously the code only printed the warning on error,
> but not when the pointer was NULL. Now the warning is printed in both
> cases!
>
> Change found with coccinelle.
>
> To: Michael Turquette <mturquette@baylibre.com>
> To: Stephen Boyd <sboyd@kernel.org>
> To: Daniel Lezcano <daniel.lezcano@kernel.org>
> To: Thomas Gleixner <tglx@kernel.org>
> Cc: linux-clk@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Philipp Hahn <phahn-oss@avm.de>
> ---
> drivers/clk/clk.c | 4 ++--
> drivers/clocksource/timer-pxa.c | 2 +-
> 2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index 47093cda9df32223c1120c3710261296027c4cd3..35146e3869a7dd93741d10b7223d4488a9216ed1 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -4558,7 +4558,7 @@ void clk_unregister(struct clk *clk)
> unsigned long flags;
> const struct clk_ops *ops;
>
> - if (!clk || WARN_ON_ONCE(IS_ERR(clk)))
> + if (WARN_ON_ONCE(IS_ERR_OR_NULL(clk)))
> return;
>
> clk_debug_unregister(clk->core);
> @@ -4744,7 +4744,7 @@ void __clk_put(struct clk *clk)
> {
> struct module *owner;
>
> - if (!clk || WARN_ON_ONCE(IS_ERR(clk)))
> + if (WARN_ON_ONCE(IS_ERR_OR_NULL(clk)))
clk_get_optional() returns NULL if the clk isn't present.
Drivers would just pass this to clk_put(). Your change here would cause
this pattern to emit a very big warning.
I don't think this change should be landed.
ChenYu
> return;
>
> clk_prepare_lock();
> diff --git a/drivers/clocksource/timer-pxa.c b/drivers/clocksource/timer-pxa.c
> index 7ad0e5adb2ffac4125c34710fc67f4b45f30331d..f65fb0b7fc318b766227e5e7a4c0fb08ba11c8f9 100644
> --- a/drivers/clocksource/timer-pxa.c
> +++ b/drivers/clocksource/timer-pxa.c
> @@ -218,7 +218,7 @@ void __init pxa_timer_nodt_init(int irq, void __iomem *base)
>
> timer_base = base;
> clk = clk_get(NULL, "OSTIMER0");
> - if (clk && !IS_ERR(clk)) {
> + if (!IS_ERR_OR_NULL(clk)) {
> clk_prepare_enable(clk);
> pxa_timer_common_init(irq, clk_get_rate(clk));
> } else {
>
> --
> 2.43.0
>
>
^ permalink raw reply
* Re: [PATCH v4 15/17] module: Introduce hash-based integrity checking
From: Eric Biggers @ 2026-03-11 1:18 UTC (permalink / raw)
To: Petr Pavlu
Cc: Thomas Weißschuh, Nathan Chancellor, Arnd Bergmann,
Luis Chamberlain, Sami Tolvanen, Daniel Gomez, Paul Moore,
James Morris, Serge E. Hallyn, Jonathan Corbet,
Madhavan Srinivasan, Michael Ellerman, Nicholas Piggin,
Naveen N Rao, Mimi Zohar, Roberto Sassu, Dmitry Kasatkin,
Eric Snowberg, Nicolas Schier, Daniel Gomez, Aaron Tomlin,
Christophe Leroy (CS GROUP), Nicolas Schier, Nicolas Bouchinet,
Xiu Jianfeng, Fabian Grünbichler, Arnout Engelen,
Mattia Rizzolo, kpcyrd, Christian Heusel, Câju Mihai-Drosi,
Sebastian Andrzej Siewior, linux-kbuild, linux-kernel, linux-arch,
linux-modules, linux-security-module, linux-doc, linuxppc-dev,
linux-integrity
In-Reply-To: <fab2af64-e396-45f9-8876-feff4002e04b@suse.com>
On Tue, Feb 03, 2026 at 01:19:20PM +0100, Petr Pavlu wrote:
> > +static unsigned int get_pow2(unsigned int val)
> > +{
> > + return 31 - __builtin_clz(val);
> > +}
> > +
> > +static unsigned int roundup_pow2(unsigned int val)
> > +{
> > + return 1 << (get_pow2(val - 1) + 1);
> > +}
> > +
> > +static unsigned int log2_roundup(unsigned int val)
> > +{
> > + return get_pow2(roundup_pow2(val));
> > +}
>
> In the edge case when the kernel is built with only one module, the code
> calls log2_roundup(1) -> roundup_pow2(1) -> get_pow2(0) ->
> __builtin_clz(0). The return value of __builtin_clz() is undefined if
> the input is zero.
A suggestion:
static unsigned int log2_roundup(unsigned int val)
{
if (val <= 1)
return 0;
return 32 - __builtin_clz(val - 1);
}
- Eric
^ permalink raw reply
* Re: [PATCH v4 15/17] module: Introduce hash-based integrity checking
From: Eric Biggers @ 2026-03-11 1:12 UTC (permalink / raw)
To: Thomas Weißschuh
Cc: Nathan Chancellor, Arnd Bergmann, Luis Chamberlain, Petr Pavlu,
Sami Tolvanen, Daniel Gomez, Paul Moore, James Morris,
Serge E. Hallyn, Jonathan Corbet, Madhavan Srinivasan,
Michael Ellerman, Nicholas Piggin, Naveen N Rao, Mimi Zohar,
Roberto Sassu, Dmitry Kasatkin, Eric Snowberg, Nicolas Schier,
Daniel Gomez, Aaron Tomlin, Christophe Leroy (CS GROUP),
Nicolas Schier, Nicolas Bouchinet, Xiu Jianfeng,
Fabian Grünbichler, Arnout Engelen, Mattia Rizzolo, kpcyrd,
Christian Heusel, Câju Mihai-Drosi,
Sebastian Andrzej Siewior, linux-kbuild, linux-kernel, linux-arch,
linux-modules, linux-security-module, linux-doc, linuxppc-dev,
linux-integrity
In-Reply-To: <20260113-module-hashes-v4-15-0b932db9b56b@weissschuh.net>
On Tue, Jan 13, 2026 at 01:28:59PM +0100, Thomas Weißschuh wrote:
> The current signature-based module integrity checking has some drawbacks
> in combination with reproducible builds. Either the module signing key
> is generated at build time, which makes the build unreproducible, or a
> static signing key is used, which precludes rebuilds by third parties
> and makes the whole build and packaging process much more complicated.
I think this actually undersells the feature. It's also much simpler
than the signature-based module authentication. The latter relies on
PKCS#7, X.509, ASN.1, OID registry, crypto_sig API, etc in addition to
the implementations of the actual signature algorithm (RSA / ECDSA /
ML-DSA) and at least one hash algorithm.
I've even seen a case where the vmlinux size decreases by almost 200KB
just by disabling module signing. That's not even counting the
signatures themselves, which ML-DSA has increased to 2-5 KB each.
The hashes are much simpler, even accounting for the Merkle tree proofs
that make them scalable. They're less likely to have vulnerabilities
like the PKCS#7 bugs the kernel has had historically. They also
eliminate the dependency on a lot of userspace libcrypto functionality
that has been causing portability problems, such as the CMS functions.
So I think this is how module authentication should have been done
originally, and I'm glad to see this is finally being fixed.
> +struct module_hashes_proof {
> + __be32 pos;
> + u8 hash_sigs[][MODULE_HASHES_HASH_SIZE];
> +} __packed;
Is the choice of big endian for consistency with struct
module_signature? Little endian is the usual choice in new code.
> diff --git a/include/linux/module_signature.h b/include/linux/module_signature.h
> index a45ce3b24403..3b510651830d 100644
> --- a/include/linux/module_signature.h
> +++ b/include/linux/module_signature.h
> @@ -18,6 +18,7 @@ enum pkey_id_type {
> PKEY_ID_PGP, /* OpenPGP generated key ID */
> PKEY_ID_X509, /* X.509 arbitrary subjectKeyIdentifier */
> PKEY_ID_PKCS7, /* Signature in PKCS#7 message */
> + PKEY_ID_MERKLE, /* Merkle proof for modules */
I recommend making the hash algorithm explicit:
PKEY_ID_MERKLE_SHA256, /* SHA-256 merkle proof for modules */
While I wouldn't encourage the addition of another hash algorithm
(specifying one good algorithm for now is absolutely the right choice),
if someone ever does need to add another one, we'd want them to be
guided to simply introduce a new value of this enum rather than hack it
in some other way.
> +static void hash_entry(const void *left, const void *right, void *out)
Byte arrays should use u8 instead of void
> diff --git a/scripts/modules-merkle-tree.c b/scripts/modules-merkle-tree.c
[...]
> +struct file_entry {
> + char *name;
> + unsigned int pos;
> + unsigned char hash[EVP_MAX_MD_SIZE];
Considering that the hash algorithm is fixed, EVP_MAX_MD_SIZE can be
replaced with a tighter local definition:
#define MAX_HASH_SIZE 32
> +static struct file_entry *fh_list;
> +static size_t num_files;
> +
> +struct leaf_hash {
> + unsigned char hash[EVP_MAX_MD_SIZE];
> +};
> +
> +struct mtree {
> + struct leaf_hash **l;
> + unsigned int *entries;
> + unsigned int levels;
> +};
'struct leaf_hash' is confusing because it's actually used for the
hashes of internal nodes, not leaf nodes.
Maybe rename it to 'struct hash' and use it for both the hashes and leaf
nodes and internal nodes.
Also, clearer naming would improve readability, e.g.:
struct merkle_tree {
struct hash **level_hashes;
unsigned int level_size;
unsigned int num_levels;
};
> +static void hash_data(void *p, unsigned int pos, size_t size, void *ret_hash)
static void hash_data(const uint8_t *data, unsigned int pos,
size_t size, struct hash *ret_hash)
> + unsigned char magic = 0x01;
uint8_t
Also, when defining these magic numbers, maybe explicitly document that
they are domain separation prefixes:
uint8_t magic = 0x01; /* domain separation prefix */
> + unsigned int pos_be;
uint32_t
> +static void hash_entry(void *left, void *right, void *ret_hash)
Could use stronger typing:
static void hash_entry(const struct hash *left, const struct hash *right,
struct hash *ret_hash)
> +static struct mtree *build_merkle(struct file_entry *fh, size_t num)
Could use clearer names, and constify the file_entry array:
static struct merkle_tree *build_merkle(const struct file_entry *files,
size_t num_files)
> + /* First level of pairs */
> + for (unsigned int i = 0; i < num; i += 2) {
> + if (i == num - 1) {
> + /* Odd number of files, no pair. Hash with itself */
> + hash_entry(fh[i].hash, fh[i].hash, mt->l[0][i / 2].hash);
> + } else {
> + hash_entry(fh[i].hash, fh[i + 1].hash, mt->l[0][i / 2].hash);
> + }
> + }
> + for (unsigned int i = 1; i < mt->levels; i++) {
> + int odd = 0;
> +
> + if (le & 1) {
> + le++;
> + odd++;
> + }
> +
> + mt->entries[i] = le / 2;
> + mt->l[i] = xcalloc(sizeof(**mt->l), le);
> +
> + for (unsigned int n = 0; n < le; n += 2) {
> + if (n == le - 2 && odd) {
> + /* Odd number of pairs, no pair. Hash with itself */
> + hash_entry(mt->l[i - 1][n].hash, mt->l[i - 1][n].hash,
> + mt->l[i][n / 2].hash);
> + } else {
> + hash_entry(mt->l[i - 1][n].hash, mt->l[i - 1][n + 1].hash,
> + mt->l[i][n / 2].hash);
> + }
> + }
> + le = mt->entries[i];
> + }
There should be an assertion at the end that we ended up with exactly 1
hash in the root level.
It might also be possible to refactor this code such that the leaf nodes
and internal nodes are handled in the same loop, rather than handling
the leaf nodes as a special case.
> +static void write_merkle_root(struct mtree *mt, const char *fp)
fp => filename since it's a string, not e.g. a 'FILE *'.
> +{
> + char buf[1024];
> + unsigned int levels;
> + unsigned char *h;
> + FILE *f;
> +
> + if (mt) {
> + levels = mt->levels;
> + h = mt->l[mt->levels - 1][0].hash;
> + } else {
> + levels = 0;
> + h = xcalloc(1, hash_size);
> + }
> +
> + f = fopen(fp, "w");
> + if (!f)
> + err(1, "Failed to create %s", buf);
Above should log the name of the file. 'buf' should be removed.
> +static char *xstrdup_replace_suffix(const char *str, const char *new_suffix)
> +{
> + const char *current_suffix;
> + size_t base_len;
> +
> + current_suffix = strchr(str, '.');
> + if (!current_suffix)
> + errx(1, "No existing suffix in '%s'", str);
This doesn't handle base names that contain a period. strrchr() would
work if the old suffix always contains exactly one period. Otherwise
another solution would be needed to identify the old suffix.
> +static __attribute__((noreturn))
> +void format(void)
usage()
> +{
> + fprintf(stderr,
> + "Usage: scripts/modules-merkle-tree <root definition>\n");
> + exit(2);
This should show both parameters, <root hash> <new suffix>
But they probably should be flipped to put the output second.
Though, is <new suffix> needed at all? It looks like it doesn't
actually affect the output.
> + hash_evp = EVP_get_digestbyname("sha256");
EVP_sha256()
> + hash_size = EVP_MD_get_size(hash_evp);
The old name 'EVP_MD_size()' would have wider compatibility.
> + ERR(hash_size <= 0, "EVP_get_digestbyname");
Log message should say EVP_MD_size
> + for (unsigned int i = 0; i < num_files; i++) {
size_t, for consistency with the type of num_files
> + fd = open(signame, O_WRONLY | O_CREAT | O_TRUNC, 0644);
> + if (fd < 0)
> + err(1, "Can't create %s", signame);
> +
> + build_proof(mt, i, fd);
> + append_module_signature_magic(fd, lseek(fd, 0, SEEK_CUR));
Maybe build_and_append_proof()?
- Eric
^ permalink raw reply
* Re: [PATCH 38/61] net: Prefer IS_ERR_OR_NULL over manual NULL check
From: Russell King (Oracle) @ 2026-03-11 0:16 UTC (permalink / raw)
To: Philipp Hahn
Cc: amd-gfx, apparmor, bpf, ceph-devel, cocci, dm-devel, dri-devel,
gfs2, intel-gfx, intel-wired-lan, iommu, kvm, linux-arm-kernel,
linux-block, linux-bluetooth, linux-btrfs, linux-cifs, linux-clk,
linux-erofs, linux-ext4, linux-fsdevel, linux-gpio, linux-hyperv,
linux-input, linux-kernel, linux-leds, linux-media, linux-mips,
linux-mm, linux-modules, linux-mtd, linux-nfs, linux-omap,
linux-phy, linux-pm, linux-rockchip, linux-s390, linux-scsi,
linux-sctp, linux-security-module, linux-sh, linux-sound,
linux-stm32, linux-trace-kernel, linux-usb, linux-wireless,
netdev, ntfs3, samba-technical, sched-ext, target-devel,
tipc-discussion, v9fs, Igor Russkikh, Andrew Lunn,
David S. Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni,
Pavan Chebbi, Michael Chan, Potnuri Bharat Teja, Tony Nguyen,
Przemek Kitszel, Taras Chornyi, Maxime Coquelin, Alexandre Torgue,
Iyappan Subramanian, Keyur Chudgar, Quan Nguyen, Heiner Kallweit
In-Reply-To: <20260310-b4-is_err_or_null-v1-38-bd63b656022d@avm.de>
On Tue, Mar 10, 2026 at 12:49:04PM +0100, Philipp Hahn wrote:
> diff --git a/drivers/net/mdio/mdio-xgene.c b/drivers/net/mdio/mdio-xgene.c
> index a8f91a4b7fed0927ee14e408000cd3a2bfb9b09a..09b30b563295c6085dc1358ac361301e5cf6b2a8 100644
> --- a/drivers/net/mdio/mdio-xgene.c
> +++ b/drivers/net/mdio/mdio-xgene.c
> @@ -265,7 +265,7 @@ struct phy_device *xgene_enet_phy_register(struct mii_bus *bus, int phy_addr)
> struct phy_device *phy_dev;
>
> phy_dev = get_phy_device(bus, phy_addr, false);
> - if (!phy_dev || IS_ERR(phy_dev))
> + if (IS_ERR_OR_NULL(phy_dev))
As noted in reply to your cover message, the check for NULL here is
incorrect - get_phy_device() returns either a valid pointer or an
error pointer, but never NULL.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!
^ permalink raw reply
* Re: [PATCH 00/61] treewide: Use IS_ERR_OR_NULL over manual NULL check - refactor
From: Russell King (Oracle) @ 2026-03-11 0:09 UTC (permalink / raw)
To: Philipp Hahn
Cc: amd-gfx, apparmor, bpf, ceph-devel, cocci, dm-devel, dri-devel,
gfs2, intel-gfx, intel-wired-lan, iommu, kvm, linux-arm-kernel,
linux-block, linux-bluetooth, linux-btrfs, linux-cifs, linux-clk,
linux-erofs, linux-ext4, linux-fsdevel, linux-gpio, linux-hyperv,
linux-input, linux-kernel, linux-leds, linux-media, linux-mips,
linux-mm, linux-modules, linux-mtd, linux-nfs, linux-omap,
linux-phy, linux-pm, linux-rockchip, linux-s390, linux-scsi,
linux-sctp, linux-security-module, linux-sh, linux-sound,
linux-stm32, linux-trace-kernel, linux-usb, linux-wireless,
netdev, ntfs3, samba-technical, sched-ext, target-devel,
tipc-discussion, v9fs, Julia Lawall, Nicolas Palix, Chris Mason,
David Sterba, Ilya Dryomov, Alex Markuze, Viacheslav Dubeyko,
Theodore Ts'o, Andreas Dilger, Steve French, Paulo Alcantara,
Ronnie Sahlberg, Shyam Prasad N, Tom Talpey, Bharath SM,
Eric Van Hensbergen, Latchesar Ionkov, Dominique Martinet,
Christian Schoenebeck, Gao Xiang, Chao Yu, Yue Hu, Jeffle Xu,
Sandeep Dhavale, Hongbo Li, Chunhai Guo, Miklos Szeredi,
Konstantin Komarov, Andreas Gruenbacher, Kees Cook, Tony Luck,
Guilherme G. Piccoli, Jan Kara, Phillip Lougher, Alexander Viro,
Christian Brauner, Jan Kara, Steven Rostedt, Masami Hiramatsu,
Mathieu Desnoyers, Tejun Heo, David Vernet, Andrea Righi,
Changwoo Min, Ingo Molnar, Peter Zijlstra, Juri Lelli,
Vincent Guittot, Dietmar Eggemann, Ben Segall, Mel Gorman,
Valentin Schneider, Luis Chamberlain, Petr Pavlu, Daniel Gomez,
Sami Tolvanen, Aaron Tomlin, Sylwester Nawrocki, Liam Girdwood,
Mark Brown, Jaroslav Kysela, Takashi Iwai, Max Filippov,
Paolo Bonzini, John Johansen, Paul Moore, James Morris,
Serge E. Hallyn, Andrew Morton, Alasdair Kergon, Mike Snitzer,
Mikulas Patocka, Benjamin Marzinski, David S. Miller, David Ahern,
Eric Dumazet, Jakub Kicinski, Paolo Abeni, Simon Horman,
Marcel Holtmann, Johan Hedberg, Luiz Augusto von Dentz,
Alexei Starovoitov, Daniel Borkmann, Jesper Dangaard Brouer,
John Fastabend, Stanislav Fomichev, Jamal Hadi Salim, Jiri Pirko,
Marcelo Ricardo Leitner, Xin Long, Trond Myklebust,
Anna Schumaker, Chuck Lever, Jeff Layton, NeilBrown,
Olga Kornievskaia, Dai Ngo, Jon Maloy, Johannes Berg,
Catalin Marinas, John Crispin, Thomas Bogendoerfer,
Yoshinori Sato, Rich Felker, John Paul Adrian Glaubitz,
Andrzej Hajda, Neil Armstrong, Robert Foss, Laurent Pinchart,
Jonas Karlman, Jernej Skrabec, Maarten Lankhorst, Maxime Ripard,
Thomas Zimmermann, David Airlie, Simona Vetter, Zhenyu Wang,
Zhi Wang, Jani Nikula, Joonas Lahtinen, Rodrigo Vivi,
Tvrtko Ursulin, Alex Deucher, Christian König, Sandy Huang,
Heiko Stübner, Andy Yan, Igor Russkikh, Andrew Lunn,
Pavan Chebbi, Michael Chan, Potnuri Bharat Teja, Tony Nguyen,
Przemek Kitszel, Taras Chornyi, Maxime Coquelin, Alexandre Torgue,
Iyappan Subramanian, Keyur Chudgar, Quan Nguyen, Heiner Kallweit,
Marc Zyngier, Thomas Gleixner, Andrew Lunn, Gregory Clement,
Sebastian Hesselbarth, Vinod Koul, Linus Walleij, Ulf Hansson,
Heiko Carstens, Vasily Gorbik, Alexander Gordeev,
Christian Borntraeger, Sven Schnelle, Martin K. Petersen,
Eduardo Valentin, Keerthy, Rafael J. Wysocki, Daniel Lezcano,
Zhang Rui, Lukasz Luba, Alex Williamson, Mark Greer,
Miquel Raynal, Richard Weinberger, Vignesh Raghavendra,
Shuah Khan, Kieran Bingham, Mauro Carvalho Chehab, Joerg Roedel,
Will Deacon, Robin Murphy, Lee Jones, Pavel Machek, Dave Penkler,
K. Y. Srinivasan, Haiyang Zhang, Wei Liu, Dexuan Cui, Long Li,
Justin Sanders, Jens Axboe, Georgi Djakov, Michael Turquette,
Stephen Boyd, Philipp Zabel, Borislav Petkov, Dave Hansen, x86,
H. Peter Anvin, Pali Rohár, Dmitry Torokhov
In-Reply-To: <20260310-b4-is_err_or_null-v1-0-bd63b656022d@avm.de>
On Tue, Mar 10, 2026 at 12:48:26PM +0100, Philipp Hahn wrote:
> While doing some static code analysis I stumbled over a common pattern,
> where IS_ERR() is combined with a NULL check. For that there is
> IS_ERR_OR_NULL().
One thing you need to check for each of these cases is whether the tests
are actually correct.
There are certainly cases amongst those that you have identified where
the check for NULL is redundant.
For example, get_phy_device() never returns NULL, yet in your netdev
patch, you have at least one instance where the return value of
get_phy_device() is checked for NULL and IS_ERR() which you then
turn into IS_ERR_OR_NULL(). Instead, the NULL check should be dropped
(as a separate patch.)
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!
^ permalink raw reply
* Re: [PATCH v2 2/2] tree-wide: rename do_exit() to task_exit()
From: Steven Rostedt @ 2026-03-11 0:02 UTC (permalink / raw)
To: Christian Brauner
Cc: Linus Torvalds, linux-kernel, linux-modules, linux-nfs, bpf,
kunit-dev, linux-doc, linux-trace-kernel, netfs, io-uring, audit,
rcu, kvm, virtualization, netdev, linux-mm, linux-security-module,
Christian Loehle, linux-fsdevel
In-Reply-To: <20260310-work-kernel-exit-v2-2-30711759d87b@kernel.org>
On Tue, 10 Mar 2026 15:56:10 +0100
Christian Brauner <brauner@kernel.org> wrote:
> diff --git a/tools/testing/selftests/bpf/progs/tracing_failure.c b/tools/testing/selftests/bpf/progs/tracing_failure.c
> index 65e485c4468c..5144f4cc5787 100644
> --- a/tools/testing/selftests/bpf/progs/tracing_failure.c
> +++ b/tools/testing/selftests/bpf/progs/tracing_failure.c
> @@ -25,7 +25,7 @@ int BPF_PROG(tracing_deny)
> return 0;
> }
>
> -SEC("?fexit/do_exit")
> +SEC("?fexit/task_exit")
> int BPF_PROG(fexit_noreturns)
> {
> return 0;
> diff --git a/tools/testing/selftests/ftrace/test.d/dynevent/fprobe_syntax_errors.tc b/tools/testing/selftests/ftrace/test.d/dynevent/fprobe_syntax_errors.tc
> index fee479295e2f..7e00d8ecd110 100644
> --- a/tools/testing/selftests/ftrace/test.d/dynevent/fprobe_syntax_errors.tc
> +++ b/tools/testing/selftests/ftrace/test.d/dynevent/fprobe_syntax_errors.tc
> @@ -82,7 +82,7 @@ check_error 'f vfs_read arg1=^' # NO_ARG_BODY
> # multiprobe errors
> if grep -q "Create/append/" README && grep -q "imm-value" README; then
> echo "f:fprobes/testevent $FUNCTION_FORK" > dynamic_events
> -check_error '^f:fprobes/testevent do_exit%return' # DIFF_PROBE_TYPE
> +check_error '^f:fprobes/testevent task_exit%return' # DIFF_PROBE_TYPE
>
> # Explicitly use printf "%s" to not interpret \1
> printf "%s" "f:fprobes/testevent $FUNCTION_FORK abcd=\\1" > dynamic_events
> diff --git a/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_multiprobe.tc b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_multiprobe.tc
> index f0d5b7777ed7..a95e3824690a 100644
> --- a/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_multiprobe.tc
> +++ b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_multiprobe.tc
> @@ -5,7 +5,7 @@
>
> # Choose 2 symbols for target
> SYM1=$FUNCTION_FORK
> -SYM2=do_exit
> +SYM2=task_exit
> EVENT_NAME=kprobes/testevent
>
> DEF1="p:$EVENT_NAME $SYM1"
> diff --git a/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_syntax_errors.tc b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_syntax_errors.tc
> index 8f1c58f0c239..b55ea3c05cfa 100644
> --- a/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_syntax_errors.tc
> +++ b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_syntax_errors.tc
> @@ -87,7 +87,7 @@ esac
> # multiprobe errors
> if grep -q "Create/append/" README && grep -q "imm-value" README; then
> echo "p:kprobes/testevent $FUNCTION_FORK" > kprobe_events
> -check_error '^r:kprobes/testevent do_exit' # DIFF_PROBE_TYPE
> +check_error '^r:kprobes/testevent task_exit' # DIFF_PROBE_TYPE
>
> # Explicitly use printf "%s" to not interpret \1
> printf "%s" "p:kprobes/testevent $FUNCTION_FORK abcd=\\1" > kprobe_events
These tests need to pass on old kernels too. So we can't just do a
"s/do_exit/task_exit/" conversion. It needs to test for task_exit first,
and if not found, fallback to do_exit.
See how we handled the _do_fork() > kernel_clone() rename:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/testing/selftests/ftrace/test.d/functions#n182
-- Steve
^ permalink raw reply
* Re: [PATCH v6] lsm: Add LSM hook security_unix_find
From: Paul Moore @ 2026-03-10 22:39 UTC (permalink / raw)
To: Günther Noack
Cc: Justin Suess, brauner, demiobenour, fahimitahera, hi, horms,
ivanov.mikhail1, jannh, jmorris, john.johansen,
konstantin.meskhidze, linux-security-module, m, matthieu, mic,
netdev, samasth.norway.ananda, serge, viro
In-Reply-To: <20260219.de5dc35ec231@gnoack.org>
On Thu, Feb 19, 2026 at 3:26 PM Günther Noack <gnoack3000@gmail.com> wrote:
> On Thu, Feb 19, 2026 at 03:04:59PM -0500, Justin Suess wrote:
> > Add a LSM hook security_unix_find.
> >
> > This hook is called to check the path of a named unix socket before a
> > connection is initiated. The peer socket may be inspected as well.
> >
> > Why existing hooks are unsuitable:
> >
> > Existing socket hooks, security_unix_stream_connect(),
> > security_unix_may_send(), and security_socket_connect() don't provide
> > TOCTOU-free / namespace independent access to the paths of sockets.
> >
> > (1) We cannot resolve the path from the struct sockaddr in existing hooks.
> > This requires another path lookup. A change in the path between the
> > two lookups will cause a TOCTOU bug.
> >
> > (2) We cannot use the struct path from the listening socket, because it
> > may be bound to a path in a different namespace than the caller,
> > resulting in a path that cannot be referenced at policy creation time.
> >
> > Cc: Günther Noack <gnoack3000@gmail.com>
> > Cc: Tingmao Wang <m@maowtm.org>
> > Signed-off-by: Justin Suess <utilityemal77@gmail.com>
> > ---
> > include/linux/lsm_hook_defs.h | 5 +++++
> > include/linux/security.h | 11 +++++++++++
> > net/unix/af_unix.c | 13 ++++++++++---
> > security/security.c | 20 ++++++++++++++++++++
> > 4 files changed, 46 insertions(+), 3 deletions(-)
...
> Reviewed-by: Günther Noack <gnoack3000@gmail.com>
>
> Thank you, this looks good. I'll include it in the next version of the
> Unix connect patch set again.
I'm looking for this patchset to review/ACK the new hook in context,
but I'm not seeing it in my inbox or lore. Did I simply miss the
patchset or is it still a work in progress? No worries if it hasn't
been posted yet, I just wanted to make sure I wasn't holding this up
any more than I already may have :)
--
paul-moore.com
^ permalink raw reply
* Re: [PATCH v2 2/2] tree-wide: rename do_exit() to task_exit()
From: Frederic Weisbecker @ 2026-03-10 22:30 UTC (permalink / raw)
To: Christian Brauner
Cc: Linus Torvalds, linux-kernel, linux-modules, linux-nfs, bpf,
kunit-dev, linux-doc, linux-trace-kernel, netfs, io-uring, audit,
rcu, kvm, virtualization, netdev, linux-mm, linux-security-module,
Christian Loehle, linux-fsdevel
In-Reply-To: <20260310-work-kernel-exit-v2-2-30711759d87b@kernel.org>
Le Tue, Mar 10, 2026 at 03:56:10PM +0100, Christian Brauner a écrit :
> Rename do_exit() to task_exit() so it's clear that this is an api and
> not a hidden internal helper.
>
> Signed-off-by: Christian Brauner <brauner@kernel.org>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
--
Frederic Weisbecker
SUSE Labs
^ permalink raw reply
* Re: [PATCH v2 1/2] kthread: remove kthread_exit()
From: Frederic Weisbecker @ 2026-03-10 22:26 UTC (permalink / raw)
To: Christian Brauner
Cc: Linus Torvalds, linux-kernel, linux-modules, linux-nfs, bpf,
kunit-dev, linux-doc, linux-trace-kernel, netfs, io-uring, audit,
rcu, kvm, virtualization, netdev, linux-mm, linux-security-module,
Christian Loehle, linux-fsdevel
In-Reply-To: <20260310-work-kernel-exit-v2-1-30711759d87b@kernel.org>
Le Tue, Mar 10, 2026 at 03:56:09PM +0100, Christian Brauner a écrit :
> In 28aaa9c39945 ("kthread: consolidate kthread exit paths to prevent use-after-free")
> we folded kthread_exit() into do_exit() when we fixed a nasty UAF bug.
> We left kthread_exit() around as an alias to do_exit(). Remove it
> completely.
Thanks for fixing that UAF! I unfortunately missed it.
>
> Reported-by: Christian Loehle <christian.loehle@arm.com>
> Link: https://lore.kernel.org/1ff1bce2-8bb4-463c-a631-16e14f4ea7e2@arm.com
> Signed-off-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
--
Frederic Weisbecker
SUSE Labs
^ permalink raw reply
* Re: [PATCH v4 10/17] module: Move integrity checks into dedicated function
From: Eric Biggers @ 2026-03-10 22:06 UTC (permalink / raw)
To: Thomas Weißschuh
Cc: Nathan Chancellor, Arnd Bergmann, Luis Chamberlain, Petr Pavlu,
Sami Tolvanen, Daniel Gomez, Paul Moore, James Morris,
Serge E. Hallyn, Jonathan Corbet, Madhavan Srinivasan,
Michael Ellerman, Nicholas Piggin, Naveen N Rao, Mimi Zohar,
Roberto Sassu, Dmitry Kasatkin, Eric Snowberg, Nicolas Schier,
Daniel Gomez, Aaron Tomlin, Christophe Leroy (CS GROUP),
Nicolas Schier, Nicolas Bouchinet, Xiu Jianfeng,
Fabian Grünbichler, Arnout Engelen, Mattia Rizzolo, kpcyrd,
Christian Heusel, Câju Mihai-Drosi,
Sebastian Andrzej Siewior, linux-kbuild, linux-kernel, linux-arch,
linux-modules, linux-security-module, linux-doc, linuxppc-dev,
linux-integrity
In-Reply-To: <20260113-module-hashes-v4-10-0b932db9b56b@weissschuh.net>
On Tue, Jan 13, 2026 at 01:28:54PM +0100, Thomas Weißschuh wrote:
> +static int module_integrity_check(struct load_info *info, int flags)
> +{
> + int err = 0;
> +
> + if (IS_ENABLED(CONFIG_MODULE_SIG))
> + err = module_sig_check(info, flags);
> +
> + return err;
> +}
Maybe module_authenticity_check()? The purpose is authenticity, not
merely integrity.
- Eric
^ permalink raw reply
* Re: [PATCH v4 09/17] module: Make module loading policy usable without MODULE_SIG
From: Eric Biggers @ 2026-03-10 22:01 UTC (permalink / raw)
To: Thomas Weißschuh
Cc: Nathan Chancellor, Arnd Bergmann, Luis Chamberlain, Petr Pavlu,
Sami Tolvanen, Daniel Gomez, Paul Moore, James Morris,
Serge E. Hallyn, Jonathan Corbet, Madhavan Srinivasan,
Michael Ellerman, Nicholas Piggin, Naveen N Rao, Mimi Zohar,
Roberto Sassu, Dmitry Kasatkin, Eric Snowberg, Nicolas Schier,
Daniel Gomez, Aaron Tomlin, Christophe Leroy (CS GROUP),
Nicolas Schier, Nicolas Bouchinet, Xiu Jianfeng,
Fabian Grünbichler, Arnout Engelen, Mattia Rizzolo, kpcyrd,
Christian Heusel, Câju Mihai-Drosi,
Sebastian Andrzej Siewior, linux-kbuild, linux-kernel, linux-arch,
linux-modules, linux-security-module, linux-doc, linuxppc-dev,
linux-integrity
In-Reply-To: <20260113-module-hashes-v4-9-0b932db9b56b@weissschuh.net>
On Tue, Jan 13, 2026 at 01:28:53PM +0100, Thomas Weißschuh wrote:
> The loading policy functionality will also be used by the hash-based
> module validation. Split it out from CONFIG_MODULE_SIG so it is usable
> by both.
>
> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
> ---
> include/linux/module.h | 8 ++++----
> kernel/module/Kconfig | 5 ++++-
> kernel/module/main.c | 26 +++++++++++++++++++++++++-
> kernel/module/signing.c | 21 ---------------------
> 4 files changed, 33 insertions(+), 27 deletions(-)
>
> diff --git a/include/linux/module.h b/include/linux/module.h
> index f288ca5cd95b..f9601cba47cd 100644
> --- a/include/linux/module.h
> +++ b/include/linux/module.h
> @@ -444,7 +444,7 @@ struct module {
> const u32 *gpl_crcs;
> bool using_gplonly_symbols;
>
> -#ifdef CONFIG_MODULE_SIG
> +#ifdef CONFIG_MODULE_SIG_POLICY
> /* Signature was verified. */
> bool sig_ok;
> #endif
[...]
> +config MODULE_SIG_POLICY
> + def_bool MODULE_SIG
Maybe MODULE_AUTH_POLICY? Hash-based module authentication does not use
signatures.
This issue appears elsewhere in the code too. There are lots of places
that still refer to module signatures or "sigs", when really module
authentication is meant.
I'm not sure how far you want to go with the renaming, but it's
something to think about. It's confusing to use the term "signature" to
mean something that is not a signature.
- Eric
^ permalink raw reply
* Re: [PATCH 0/3] Firmware LSM hook
From: Paul Moore @ 2026-03-10 21:40 UTC (permalink / raw)
To: Leon Romanovsky
Cc: James Morris, Serge E. Hallyn, Jason Gunthorpe, Saeed Mahameed,
Itay Avraham, Dave Jiang, Jonathan Cameron, linux-security-module,
linux-kernel, linux-rdma, Chiara Meiohas, Maher Sanalla,
Edward Srouji
In-Reply-To: <20260310193000.GM12611@unreal>
On Tue, Mar 10, 2026 at 3:30 PM Leon Romanovsky <leon@kernel.org> wrote:
> On Tue, Mar 10, 2026 at 02:24:40PM -0400, Paul Moore wrote:
> > On Tue, Mar 10, 2026 at 5:07 AM Leon Romanovsky <leon@kernel.org> wrote:
> > > On Mon, Mar 09, 2026 at 07:10:25PM -0400, Paul Moore wrote:
> > > > On Mon, Mar 9, 2026 at 3:37 PM Leon Romanovsky <leon@kernel.org> wrote:
> > > > > On Mon, Mar 09, 2026 at 02:32:39PM -0400, Paul Moore wrote:
> > > > > > On Mon, Mar 9, 2026 at 7:15 AM Leon Romanovsky <leon@kernel.org> wrote:
> >
> > ...
> >
> > > > > > Hi Leon,
> > > > > >
> > > > > > At the link below, you'll find guidance on submitting new LSM hooks.
> > > > > > Please take a look and let me know if you have any questions.
> > > > > >
> > > > > > https://github.com/LinuxSecurityModule/kernel/blob/main/README.md#new-lsm-hooks
> > > > >
> > > > > I assume that you are referring to this part:
> > > >
> > > > I'm referring to all of the guidance, but yes, at the very least that
> > > > is something that I think we need to see in a future revision of this
> > > > patchset.
> > > >
> > > > > * New LSM hooks must demonstrate their usefulness by providing a meaningful
> > > > > implementation for at least one in-kernel LSM. The goal is to demonstrate
> > > > > the purpose and expected semantics of the hooks. Out of tree kernel code,
> > > > > and pass through implementations, such as the BPF LSM, are not eligible
> > > > > for LSM hook reference implementations.
> > > > >
> > > > > The point is that we are not inspecting a kernel call, but the FW mailbox,
> > > > > which has very little meaning to the kernel. From the kernel's perspective,
> > > > > all relevant checks have already been performed, but the existing capability
> > > > > granularity does not allow us to distinguish between FW_CMD1 and FW_CMD2.
> > > >
> > > > It might help if you could phrase this differently, as I'm not
> > > > entirely clear on your argument. LSMs are not limited to enforcing
> > > > access controls on requests the kernel understands (see the SELinux
> > > > userspace object manager concept), and the idea of access controls
> > > > with greater granularity than capabilities is one of the main reasons
> > > > people look to LSMs for access control (SELinux, AppArmor, Smack,
> > > > etc.).
> > >
> > > I should note that my understanding of LSM is limited, so some parts of my
> > > answers may be inaccurate.
> > >
> > > What I am referring to is a different level of granularity — specifically,
> > > the internals of the firmware commands. In the proposed approach, BPF
> > > programs would make decisions based on data passed through the mailbox.
> > > That mailbox format varies across vendors, and may even differ between
> > > firmware versions from the same vendor.
> >
> > That helps, thank you.
> >
> > > > > Here we propose a generic interface that can be applied to all FWCTL
> > > > > devices without out-of-tree kernel code at all.
> > > >
> > > > I expected to see a patch implementing some meaningful support for
> > > > access controls using these hooks in one of the existing LSMs, I did
> > > > not see that in this patchset.
> > >
> > > In some cases, the mailbox is forwarded from user space unchanged, but
> > > in others the kernel modifies it before submitting it to the FW.
> >
> > Without a standard format, opcode definitions, etc. I suspect
> > integrating this into an LSM will present a number of challenges.
>
> The opcode is relatively easy to extract from the mailbox and pass to the LSM.
> All drivers implement some variant of mlx5ctl_validate_rpc()/devx_is_general_cmd()
> to validate the opcode. The problem is that this check alone is not sufficient.
>
> > Instead of performing an LSM access control check before submitting
> > the firmware command, it might be easier from an LSM perspective to
> > have the firmware call into the kernel/LSM for an access control
> > decision before performing a security-relevant action.
>
> Ultimately, the LSM must make a decision for each executed firmware
> command. This will need to be handled one way or another, and will
> likely require parsing the mailbox again.
As it's unlikely that parsing the mailbox is something that a LSM will
want to handle, my suggestion was to leverage the existing mailbox
parsing in the firmware and require the firmware to call into the LSM
when authorization is needed.
> > This removes the challenge of parsing/interpreting the arbitrary firmware commands,
> > but it does add some additional complexity of having to generically
> > represent the security relevant actions the firmware might request
>
> The difference here is that the proposed LSM hook is intended to disable
> certain functionality provided by the firmware, effectively depending on
> the operator’s preferences.
My suggestion would also allow a LSM hook to disable certain firmware
functionality; however, the firmware itself would need to call the LSM
to check if the functionality is authorized.
--
paul-moore.com
^ permalink raw reply
* Re: [PATCH v4 06/17] kbuild: add stamp file for vmlinux BTF data
From: Eric Biggers @ 2026-03-10 21:36 UTC (permalink / raw)
To: Thomas Weißschuh
Cc: Nathan Chancellor, Arnd Bergmann, Luis Chamberlain, Petr Pavlu,
Sami Tolvanen, Daniel Gomez, Paul Moore, James Morris,
Serge E. Hallyn, Jonathan Corbet, Madhavan Srinivasan,
Michael Ellerman, Nicholas Piggin, Naveen N Rao, Mimi Zohar,
Roberto Sassu, Dmitry Kasatkin, Eric Snowberg, Nicolas Schier,
Daniel Gomez, Aaron Tomlin, Christophe Leroy (CS GROUP),
Nicolas Schier, Nicolas Bouchinet, Xiu Jianfeng,
Fabian Grünbichler, Arnout Engelen, Mattia Rizzolo, kpcyrd,
Christian Heusel, Câju Mihai-Drosi,
Sebastian Andrzej Siewior, linux-kbuild, linux-kernel, linux-arch,
linux-modules, linux-security-module, linux-doc, linuxppc-dev,
linux-integrity
In-Reply-To: <20260113-module-hashes-v4-6-0b932db9b56b@weissschuh.net>
On Tue, Jan 13, 2026 at 01:28:50PM +0100, Thomas Weißschuh wrote:
> The upcoming module hashes functionality will build the modules in
> between the generation of the BTF data and the final link of vmlinux.
> Having a dependency from the modules on vmlinux would make this
> impossible as it would mean having a cyclic dependency.
> Break this cyclic dependency by introducing a new target.
>
> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
> ---
> scripts/Makefile.modfinal | 4 ++--
> scripts/link-vmlinux.sh | 6 ++++++
> 2 files changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal
> index 149e12ff5700..adfef1e002a9 100644
> --- a/scripts/Makefile.modfinal
> +++ b/scripts/Makefile.modfinal
> @@ -56,8 +56,8 @@ if_changed_except = $(if $(call newer_prereqs_except,$(2))$(cmd-check), \
> printf '%s\n' 'savedcmd_$@ := $(make-cmd)' > $(dot-target).cmd, @:)
>
> # Re-generate module BTFs if either module's .ko or vmlinux changed
> -%.ko: %.o %.mod.o .module-common.o $(objtree)/scripts/module.lds $(and $(CONFIG_DEBUG_INFO_BTF_MODULES),$(KBUILD_BUILTIN),$(objtree)/vmlinux) FORCE
> - +$(call if_changed_except,ld_ko_o,$(objtree)/vmlinux)
> +%.ko: %.o %.mod.o .module-common.o $(objtree)/scripts/module.lds $(and $(CONFIG_DEBUG_INFO_BTF_MODULES),$(KBUILD_BUILTIN),$(objtree)/.tmp_vmlinux_btf.stamp) FORCE
> + +$(call if_changed_except,ld_ko_o,$(objtree)/.tmp_vmlinux_btf.stamp)
> ifdef CONFIG_DEBUG_INFO_BTF_MODULES
> +$(if $(newer-prereqs),$(call cmd,btf_ko))
> endif
> diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
> index 4ab44c73da4d..8c98f8645a5c 100755
> --- a/scripts/link-vmlinux.sh
> +++ b/scripts/link-vmlinux.sh
> @@ -111,6 +111,7 @@ vmlinux_link()
> gen_btf()
> {
> local btf_data=${1}.btf.o
> + local btf_stamp=.tmp_vmlinux_btf.stamp
>
> info BTF "${btf_data}"
> LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1}
> @@ -131,6 +132,11 @@ gen_btf()
> fi
> printf "${et_rel}" | dd of="${btf_data}" conv=notrunc bs=1 seek=16 status=none
>
> + info STAMP $btf_stamp
> + if ! cmp --silent $btf_data $btf_stamp; then
> + cp $btf_data $btf_stamp
> + fi
A "stamp file" is traditionally an empty file that is written when some
build step has completed. The above code is instead copying the entire
.tmp_vmlinux1.btf.o file (megabytes in size) to .tmp_vmlinux_btf.stamp.
So, it's not clear to me why the stamp file is needed at all, versus
depending directly on .tmp_vmlinux1.btf.o.
I guess 'make' doesn't know about the dependencies of
.tmp_vmlinux1.btf.o. But the same is true of the stamp file, right? So
either way, how would 'make' know to finish rebuilding the file before
starting to execute the "Re-generate module BTFs" rule?
Also, passing the long option '--silent' to 'cmp' creates a dependency
on the GNU implementation of 'cmp', which isn't documented as a kernel
build dependency. Probably better to use the short option '-s'.
Also, the stamp file isn't being deleted by 'make clean'. It looks like
it would need to be added to cleanup() in link-vmlinux.sh.
- Eric
^ permalink raw reply
* Re: [PATCH v2] landlock: Fix kernel-doc warning for pointer-to-array parameters
From: Günther Noack @ 2026-03-10 21:13 UTC (permalink / raw)
To: Mickaël Salaün
Cc: Günther Noack, linux-security-module, Jonathan Corbet
In-Reply-To: <20260310172004.1839864-1-mic@digikod.net>
On Tue, Mar 10, 2026 at 06:20:03PM +0100, Mickaël Salaün wrote:
> The insert_rule() and create_rule() functions take a
> pointer-to-flexible-array parameter declared as:
>
> const struct landlock_layer (*const layers)[]
>
> The kernel-doc parser cannot handle a qualifier between * and the
> parameter name in this syntax, producing spurious "Invalid param" and
> "not described" warnings.
>
> Remove the const qualifier of the "layers" argument to avoid this
> parsing issue.
>
> Cc: Günther Noack <gnoack@google.com>
> Cc: Jonathan Corbet <corbet@lwn.net>
> Signed-off-by: Mickaël Salaün <mic@digikod.net>
> ---
>
> Changes since v1:
> https://lore.kernel.org/r/20260304193134.250495-1-mic@digikod.net
> - Remove const instead of using a typedef (suggested by Günther).
> ---
> security/landlock/ruleset.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
> index 3234a5bc11ff..181df7736bb9 100644
> --- a/security/landlock/ruleset.c
> +++ b/security/landlock/ruleset.c
> @@ -107,7 +107,7 @@ static bool is_object_pointer(const enum landlock_key_type key_type)
>
> static struct landlock_rule *
> create_rule(const struct landlock_id id,
> - const struct landlock_layer (*const layers)[], const u32 num_layers,
> + const struct landlock_layer (*layers)[], const u32 num_layers,
> const struct landlock_layer *const new_layer)
> {
> struct landlock_rule *new_rule;
> @@ -206,7 +206,7 @@ static void build_check_ruleset(void)
> */
> static int insert_rule(struct landlock_ruleset *const ruleset,
> const struct landlock_id id,
> - const struct landlock_layer (*const layers)[],
> + const struct landlock_layer (*layers)[],
> const size_t num_layers)
> {
> struct rb_node **walker_node;
> --
> 2.53.0
>
Reviewed-by: Günther Noack <gnoack3000@gmail.com>
^ permalink raw reply
* Re: [PATCH v4 04/17] module: Make mod_verify_sig() static
From: Eric Biggers @ 2026-03-10 21:12 UTC (permalink / raw)
To: Thomas Weißschuh
Cc: Nathan Chancellor, Arnd Bergmann, Luis Chamberlain, Petr Pavlu,
Sami Tolvanen, Daniel Gomez, Paul Moore, James Morris,
Serge E. Hallyn, Jonathan Corbet, Madhavan Srinivasan,
Michael Ellerman, Nicholas Piggin, Naveen N Rao, Mimi Zohar,
Roberto Sassu, Dmitry Kasatkin, Eric Snowberg, Nicolas Schier,
Daniel Gomez, Aaron Tomlin, Christophe Leroy (CS GROUP),
Nicolas Schier, Nicolas Bouchinet, Xiu Jianfeng,
Fabian Grünbichler, Arnout Engelen, Mattia Rizzolo, kpcyrd,
Christian Heusel, Câju Mihai-Drosi,
Sebastian Andrzej Siewior, linux-kbuild, linux-kernel, linux-arch,
linux-modules, linux-security-module, linux-doc, linuxppc-dev,
linux-integrity
In-Reply-To: <20260113-module-hashes-v4-4-0b932db9b56b@weissschuh.net>
On Tue, Jan 13, 2026 at 01:28:48PM +0100, Thomas Weißschuh wrote:
> It is not used outside of signing.c.
>
> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
> ---
> kernel/module/internal.h | 1 -
> kernel/module/signing.c | 2 +-
> 2 files changed, 1 insertion(+), 2 deletions(-)
Reviewed-by: Eric Biggers <ebiggers@kernel.org>
- Eric
^ permalink raw reply
* Re: [PATCH v4 03/17] ima: efi: Drop unnecessary check for CONFIG_MODULE_SIG/CONFIG_KEXEC_SIG
From: Eric Biggers @ 2026-03-10 21:11 UTC (permalink / raw)
To: Thomas Weißschuh
Cc: Nathan Chancellor, Arnd Bergmann, Luis Chamberlain, Petr Pavlu,
Sami Tolvanen, Daniel Gomez, Paul Moore, James Morris,
Serge E. Hallyn, Jonathan Corbet, Madhavan Srinivasan,
Michael Ellerman, Nicholas Piggin, Naveen N Rao, Mimi Zohar,
Roberto Sassu, Dmitry Kasatkin, Eric Snowberg, Nicolas Schier,
Daniel Gomez, Aaron Tomlin, Christophe Leroy (CS GROUP),
Nicolas Schier, Nicolas Bouchinet, Xiu Jianfeng,
Fabian Grünbichler, Arnout Engelen, Mattia Rizzolo, kpcyrd,
Christian Heusel, Câju Mihai-Drosi,
Sebastian Andrzej Siewior, linux-kbuild, linux-kernel, linux-arch,
linux-modules, linux-security-module, linux-doc, linuxppc-dev,
linux-integrity
In-Reply-To: <20260113-module-hashes-v4-3-0b932db9b56b@weissschuh.net>
On Tue, Jan 13, 2026 at 01:28:47PM +0100, Thomas Weißschuh wrote:
> When configuration settings are disabled the guarded functions are
> defined as empty stubs, so the check is unnecessary.
> The specific configuration option for set_module_sig_enforced() is
> about to change and removing the checks avoids some later churn.
>
> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
> ---
> security/integrity/ima/ima_efi.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
Reviewed-by: Eric Biggers <ebiggers@kernel.org>
- Eric
^ permalink raw reply
* Re: [PATCH v4 02/17] powerpc/ima: Drop unnecessary check for CONFIG_MODULE_SIG
From: Eric Biggers @ 2026-03-10 21:11 UTC (permalink / raw)
To: Thomas Weißschuh
Cc: Nathan Chancellor, Arnd Bergmann, Luis Chamberlain, Petr Pavlu,
Sami Tolvanen, Daniel Gomez, Paul Moore, James Morris,
Serge E. Hallyn, Jonathan Corbet, Madhavan Srinivasan,
Michael Ellerman, Nicholas Piggin, Naveen N Rao, Mimi Zohar,
Roberto Sassu, Dmitry Kasatkin, Eric Snowberg, Nicolas Schier,
Daniel Gomez, Aaron Tomlin, Christophe Leroy (CS GROUP),
Nicolas Schier, Nicolas Bouchinet, Xiu Jianfeng,
Fabian Grünbichler, Arnout Engelen, Mattia Rizzolo, kpcyrd,
Christian Heusel, Câju Mihai-Drosi,
Sebastian Andrzej Siewior, linux-kbuild, linux-kernel, linux-arch,
linux-modules, linux-security-module, linux-doc, linuxppc-dev,
linux-integrity
In-Reply-To: <20260113-module-hashes-v4-2-0b932db9b56b@weissschuh.net>
On Tue, Jan 13, 2026 at 01:28:46PM +0100, Thomas Weißschuh wrote:
> When CONFIG_MODULE_SIG is disabled set_module_sig_enforced() is defined
> as an empty stub, so the check is unnecessary.
> The specific configuration option for set_module_sig_enforced() is
> about to change and removing the check avoids some later churn.
>
> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
> ---
> arch/powerpc/kernel/ima_arch.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
Reviewed-by: Eric Biggers <ebiggers@kernel.org>
- Eric
^ permalink raw reply
* Re: [PATCH 0/3] Firmware LSM hook
From: Leon Romanovsky @ 2026-03-10 19:30 UTC (permalink / raw)
To: Paul Moore
Cc: James Morris, Serge E. Hallyn, Jason Gunthorpe, Saeed Mahameed,
Itay Avraham, Dave Jiang, Jonathan Cameron, linux-security-module,
linux-kernel, linux-rdma, Chiara Meiohas, Maher Sanalla,
Edward Srouji
In-Reply-To: <CAHC9VhTKsOYrs8Wh-O548=2gE7N_gkBy+q05+atcR=D+30uQ=w@mail.gmail.com>
On Tue, Mar 10, 2026 at 02:24:40PM -0400, Paul Moore wrote:
> On Tue, Mar 10, 2026 at 5:07 AM Leon Romanovsky <leon@kernel.org> wrote:
> > On Mon, Mar 09, 2026 at 07:10:25PM -0400, Paul Moore wrote:
> > > On Mon, Mar 9, 2026 at 3:37 PM Leon Romanovsky <leon@kernel.org> wrote:
> > > > On Mon, Mar 09, 2026 at 02:32:39PM -0400, Paul Moore wrote:
> > > > > On Mon, Mar 9, 2026 at 7:15 AM Leon Romanovsky <leon@kernel.org> wrote:
>
> ...
>
> > > > > Hi Leon,
> > > > >
> > > > > At the link below, you'll find guidance on submitting new LSM hooks.
> > > > > Please take a look and let me know if you have any questions.
> > > > >
> > > > > https://github.com/LinuxSecurityModule/kernel/blob/main/README.md#new-lsm-hooks
> > > >
> > > > I assume that you are referring to this part:
> > >
> > > I'm referring to all of the guidance, but yes, at the very least that
> > > is something that I think we need to see in a future revision of this
> > > patchset.
> > >
> > > > * New LSM hooks must demonstrate their usefulness by providing a meaningful
> > > > implementation for at least one in-kernel LSM. The goal is to demonstrate
> > > > the purpose and expected semantics of the hooks. Out of tree kernel code,
> > > > and pass through implementations, such as the BPF LSM, are not eligible
> > > > for LSM hook reference implementations.
> > > >
> > > > The point is that we are not inspecting a kernel call, but the FW mailbox,
> > > > which has very little meaning to the kernel. From the kernel's perspective,
> > > > all relevant checks have already been performed, but the existing capability
> > > > granularity does not allow us to distinguish between FW_CMD1 and FW_CMD2.
> > >
> > > It might help if you could phrase this differently, as I'm not
> > > entirely clear on your argument. LSMs are not limited to enforcing
> > > access controls on requests the kernel understands (see the SELinux
> > > userspace object manager concept), and the idea of access controls
> > > with greater granularity than capabilities is one of the main reasons
> > > people look to LSMs for access control (SELinux, AppArmor, Smack,
> > > etc.).
> >
> > I should note that my understanding of LSM is limited, so some parts of my
> > answers may be inaccurate.
> >
> > What I am referring to is a different level of granularity — specifically,
> > the internals of the firmware commands. In the proposed approach, BPF
> > programs would make decisions based on data passed through the mailbox.
> > That mailbox format varies across vendors, and may even differ between
> > firmware versions from the same vendor.
>
> That helps, thank you.
>
> > > > Here we propose a generic interface that can be applied to all FWCTL
> > > > devices without out-of-tree kernel code at all.
> > >
> > > I expected to see a patch implementing some meaningful support for
> > > access controls using these hooks in one of the existing LSMs, I did
> > > not see that in this patchset.
> >
> > In some cases, the mailbox is forwarded from user space unchanged, but
> > in others the kernel modifies it before submitting it to the FW.
>
> Without a standard format, opcode definitions, etc. I suspect
> integrating this into an LSM will present a number of challenges.
The opcode is relatively easy to extract from the mailbox and pass to the LSM.
All drivers implement some variant of mlx5ctl_validate_rpc()/devx_is_general_cmd()
to validate the opcode. The problem is that this check alone is not sufficient.
> Instead of performing an LSM access control check before submitting
> the firmware command, it might be easier from an LSM perspective to
> have the firmware call into the kernel/LSM for an access control
> decision before performing a security-relevant action.
Ultimately, the LSM must make a decision for each executed firmware
command. This will need to be handled one way or another, and will
likely require parsing the mailbox again.
> This removes the challenge of parsing/interpreting the arbitrary firmware commands,
> but it does add some additional complexity of having to generically
> represent the security relevant actions the firmware might request
The difference here is that the proposed LSM hook is intended to disable
certain functionality provided by the firmware, effectively depending on
the operator’s preferences.
This is not a security‑sensitive operation that requires strict
restriction.
> (this is somewhat similar to how the LSM framework doesn't necessarily
> hook the syscalls, but the actions the syscalls perform). Yes, one
> does have to trust the firmware in this approach, but given the
> relationship between the firmware and associated hardware, I think
> users are implicitly required to trust their firmware in the vast
> majority of cases.
They trust the firmware and the kernel, but they do not trust the actual
non‑privileged users of that firmware.
Thanks
>
> --
> paul-moore.com
>
^ permalink raw reply
* [PATCH v1] selftests/landlock: Test tsync interruption and cancellation paths
From: Mickaël Salaün @ 2026-03-10 19:04 UTC (permalink / raw)
To: Günther Noack
Cc: Mickaël Salaün, linux-security-module, Justin Suess,
Tingmao Wang, Yihan Ding
Add tsync_interrupt test to exercise the signal interruption path in
landlock_restrict_sibling_threads(). When a signal interrupts
wait_for_completion_interruptible() while the calling thread waits for
sibling threads to finish credential preparation, the kernel:
1. Sets ERESTARTNOINTR to request a transparent syscall restart.
2. Calls cancel_tsync_works() to opportunistically dequeue task works
that have not started running yet.
3. Breaks out of the preparation loop, then unblocks remaining
task works via complete_all() and waits for them to finish.
4. Returns the error, causing abort_creds() in the syscall handler.
Specifically, cancel_tsync_works() in its entirety, the ERESTARTNOINTR
error branch in landlock_restrict_sibling_threads(), and the
abort_creds() error branch in the landlock_restrict_self() syscall
handler are timing-dependent and not exercised by the existing tsync
tests, making code coverage measurements non-deterministic.
The test spawns a signaler thread that rapidly sends SIGUSR1 to the
calling thread while it performs landlock_restrict_self() with
LANDLOCK_RESTRICT_SELF_TSYNC. Since ERESTARTNOINTR causes a
transparent restart, userspace always sees the syscall succeed.
This is a best-effort coverage test: the interruption path is exercised
when the signal lands during the preparation wait, which depends on
thread scheduling. The test creates enough idle sibling threads (200)
to ensure multiple serialized waves of credential preparation even on
machines with many cores (e.g., 64), widening the window for the
signaler. Deterministic coverage would require wrapping the wait call
with ALLOW_ERROR_INJECTION() and using CONFIG_FAIL_FUNCTION.
Cc: Günther Noack <gnoack@google.com>
Cc: Justin Suess <utilityemal77@gmail.com>
Cc: Tingmao Wang <m@maowtm.org>
Cc: Yihan Ding <dingyihan@uniontech.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---
tools/testing/selftests/landlock/tsync_test.c | 91 ++++++++++++++++++-
1 file changed, 90 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/landlock/tsync_test.c b/tools/testing/selftests/landlock/tsync_test.c
index 37ef0d2270db..2b9ad4f154f4 100644
--- a/tools/testing/selftests/landlock/tsync_test.c
+++ b/tools/testing/selftests/landlock/tsync_test.c
@@ -6,9 +6,10 @@
*/
#define _GNU_SOURCE
+#include <linux/landlock.h>
#include <pthread.h>
+#include <signal.h>
#include <sys/prctl.h>
-#include <linux/landlock.h>
#include "common.h"
@@ -158,4 +159,92 @@ TEST(competing_enablement)
EXPECT_EQ(0, close(ruleset_fd));
}
+static void signal_nop_handler(int sig)
+{
+}
+
+struct signaler_data {
+ pthread_t target;
+ volatile bool stop;
+};
+
+static void *signaler_thread(void *data)
+{
+ struct signaler_data *sd = data;
+
+ while (!sd->stop)
+ pthread_kill(sd->target, SIGUSR1);
+
+ return NULL;
+}
+
+/*
+ * Number of idle sibling threads. This must be large enough that even on
+ * machines with many cores, the sibling threads cannot all complete their
+ * credential preparation in a single parallel wave, otherwise the signaler
+ * thread has no window to interrupt wait_for_completion_interruptible().
+ * 200 threads on a 64-core machine yields ~3 serialized waves, giving the
+ * tight signal loop enough time to land an interruption.
+ */
+#define NUM_IDLE_THREADS 200
+
+/*
+ * Exercises the tsync interruption and cancellation paths in tsync.c.
+ *
+ * When a signal interrupts the calling thread while it waits for sibling
+ * threads to finish their credential preparation
+ * (wait_for_completion_interruptible in landlock_restrict_sibling_threads),
+ * the kernel sets ERESTARTNOINTR, cancels queued task works that have not
+ * started yet (cancel_tsync_works), then waits for the remaining works to
+ * finish. On the error return, syscalls.c aborts the prepared credentials.
+ * The kernel automatically restarts the syscall, so userspace sees success.
+ */
+TEST(tsync_interrupt)
+{
+ size_t i;
+ pthread_t threads[NUM_IDLE_THREADS];
+ pthread_t signaler;
+ struct signaler_data sd;
+ struct sigaction sa = {};
+ const int ruleset_fd = create_ruleset(_metadata);
+
+ disable_caps(_metadata);
+
+ /* Install a no-op SIGUSR1 handler so the signal does not kill us. */
+ sa.sa_handler = signal_nop_handler;
+ sigemptyset(&sa.sa_mask);
+ ASSERT_EQ(0, sigaction(SIGUSR1, &sa, NULL));
+
+ ASSERT_EQ(0, prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0));
+
+ for (i = 0; i < NUM_IDLE_THREADS; i++)
+ ASSERT_EQ(0, pthread_create(&threads[i], NULL, idle, NULL));
+
+ /*
+ * Start a signaler thread that continuously sends SIGUSR1 to the
+ * calling thread. This maximizes the chance of interrupting
+ * wait_for_completion_interruptible() in the kernel's tsync path.
+ */
+ sd.target = pthread_self();
+ sd.stop = false;
+ ASSERT_EQ(0, pthread_create(&signaler, NULL, signaler_thread, &sd));
+
+ /*
+ * The syscall may be interrupted and transparently restarted by the
+ * kernel (ERESTARTNOINTR). From userspace, it should always succeed.
+ */
+ EXPECT_EQ(0, landlock_restrict_self(ruleset_fd,
+ LANDLOCK_RESTRICT_SELF_TSYNC));
+
+ sd.stop = true;
+ ASSERT_EQ(0, pthread_join(signaler, NULL));
+
+ for (i = 0; i < NUM_IDLE_THREADS; i++) {
+ ASSERT_EQ(0, pthread_cancel(threads[i]));
+ ASSERT_EQ(0, pthread_join(threads[i], NULL));
+ }
+
+ EXPECT_EQ(0, close(ruleset_fd));
+}
+
TEST_HARNESS_MAIN
--
2.53.0
^ permalink raw reply related
* Re: [PATCH 00/61] treewide: Use IS_ERR_OR_NULL over manual NULL check - refactor
From: Kuan-Wei Chiu @ 2026-03-10 18:40 UTC (permalink / raw)
To: Philipp Hahn
Cc: amd-gfx, apparmor, bpf, ceph-devel, cocci, dm-devel, dri-devel,
gfs2, intel-gfx, intel-wired-lan, iommu, kvm, linux-arm-kernel,
linux-block, linux-bluetooth, linux-btrfs, linux-cifs, linux-clk,
linux-erofs, linux-ext4, linux-fsdevel, linux-gpio, linux-hyperv,
linux-input, linux-kernel, linux-leds, linux-media, linux-mips,
linux-mm, linux-modules, linux-mtd, linux-nfs, linux-omap,
linux-phy, linux-pm, linux-rockchip, linux-s390, linux-scsi,
linux-sctp, linux-security-module, linux-sh, linux-sound,
linux-stm32, linux-trace-kernel, linux-usb, linux-wireless,
netdev, ntfs3, samba-technical, sched-ext, target-devel,
tipc-discussion, v9fs
In-Reply-To: <20260310-b4-is_err_or_null-v1-0-bd63b656022d@avm.de>
Hi Philipp,
On Tue, Mar 10, 2026 at 12:48:26PM +0100, Philipp Hahn wrote:
> While doing some static code analysis I stumbled over a common pattern,
> where IS_ERR() is combined with a NULL check. For that there is
> IS_ERR_OR_NULL().
>
> I've written a Coccinelle patch to find and patch those instances.
> The patches follow grouped by subsystem.
>
> Patches 55-58 may be dropped as they have a (minor?) semantic change:
> They use WARN_ON() or WARN_ON_ONCE(), but only in the IS_ERR() path, not
> for the NULL check. Iff it is okay to print the warning also for NULL,
> then the patches can be applied.
>
> While generating the patch set `checkpatch` complained about mixing
> [un]likely() with IS_ERR_OR_NULL(), which already uses likely()
> internally. I found and fixed several locations, where that combination
> has been used.
Thanks for the patchset. However, I think we need a explanation for why
switching to IS_ERR_OR_NULL() is an improvement over the existing code.
IMHO, the necessity of IS_ERR_OR_NULL() often highlights a confusing or
flawed API design. It usually implies that the caller is unsure whether
a failure results in an error pointer or a NULL pointer. Rather than
doing a treewide conversion of this pattern, I believe it would be much
more meaningful to review these instances case-by-case and fix the
underlying APIs or caller logic instead.
Additionally, a treewide refactoring like this has the practical
drawback of creating unnecessary merge conflicts when backporting to
stable trees.
Regards,
Kuan-Wei
^ permalink raw reply
* Re: [PATCH 0/3] Firmware LSM hook
From: Paul Moore @ 2026-03-10 18:24 UTC (permalink / raw)
To: Leon Romanovsky
Cc: James Morris, Serge E. Hallyn, Jason Gunthorpe, Saeed Mahameed,
Itay Avraham, Dave Jiang, Jonathan Cameron, linux-security-module,
linux-kernel, linux-rdma, Chiara Meiohas, Maher Sanalla,
Edward Srouji
In-Reply-To: <20260310090733.GA12611@unreal>
On Tue, Mar 10, 2026 at 5:07 AM Leon Romanovsky <leon@kernel.org> wrote:
> On Mon, Mar 09, 2026 at 07:10:25PM -0400, Paul Moore wrote:
> > On Mon, Mar 9, 2026 at 3:37 PM Leon Romanovsky <leon@kernel.org> wrote:
> > > On Mon, Mar 09, 2026 at 02:32:39PM -0400, Paul Moore wrote:
> > > > On Mon, Mar 9, 2026 at 7:15 AM Leon Romanovsky <leon@kernel.org> wrote:
...
> > > > Hi Leon,
> > > >
> > > > At the link below, you'll find guidance on submitting new LSM hooks.
> > > > Please take a look and let me know if you have any questions.
> > > >
> > > > https://github.com/LinuxSecurityModule/kernel/blob/main/README.md#new-lsm-hooks
> > >
> > > I assume that you are referring to this part:
> >
> > I'm referring to all of the guidance, but yes, at the very least that
> > is something that I think we need to see in a future revision of this
> > patchset.
> >
> > > * New LSM hooks must demonstrate their usefulness by providing a meaningful
> > > implementation for at least one in-kernel LSM. The goal is to demonstrate
> > > the purpose and expected semantics of the hooks. Out of tree kernel code,
> > > and pass through implementations, such as the BPF LSM, are not eligible
> > > for LSM hook reference implementations.
> > >
> > > The point is that we are not inspecting a kernel call, but the FW mailbox,
> > > which has very little meaning to the kernel. From the kernel's perspective,
> > > all relevant checks have already been performed, but the existing capability
> > > granularity does not allow us to distinguish between FW_CMD1 and FW_CMD2.
> >
> > It might help if you could phrase this differently, as I'm not
> > entirely clear on your argument. LSMs are not limited to enforcing
> > access controls on requests the kernel understands (see the SELinux
> > userspace object manager concept), and the idea of access controls
> > with greater granularity than capabilities is one of the main reasons
> > people look to LSMs for access control (SELinux, AppArmor, Smack,
> > etc.).
>
> I should note that my understanding of LSM is limited, so some parts of my
> answers may be inaccurate.
>
> What I am referring to is a different level of granularity — specifically,
> the internals of the firmware commands. In the proposed approach, BPF
> programs would make decisions based on data passed through the mailbox.
> That mailbox format varies across vendors, and may even differ between
> firmware versions from the same vendor.
That helps, thank you.
> > > Here we propose a generic interface that can be applied to all FWCTL
> > > devices without out-of-tree kernel code at all.
> >
> > I expected to see a patch implementing some meaningful support for
> > access controls using these hooks in one of the existing LSMs, I did
> > not see that in this patchset.
>
> In some cases, the mailbox is forwarded from user space unchanged, but
> in others the kernel modifies it before submitting it to the FW.
Without a standard format, opcode definitions, etc. I suspect
integrating this into an LSM will present a number of challenges.
Instead of performing an LSM access control check before submitting
the firmware command, it might be easier from an LSM perspective to
have the firmware call into the kernel/LSM for an access control
decision before performing a security-relevant action. This removes
the challenge of parsing/interpreting the arbitrary firmware commands,
but it does add some additional complexity of having to generically
represent the security relevant actions the firmware might request
(this is somewhat similar to how the LSM framework doesn't necessarily
hook the syscalls, but the actions the syscalls perform). Yes, one
does have to trust the firmware in this approach, but given the
relationship between the firmware and associated hardware, I think
users are implicitly required to trust their firmware in the vast
majority of cases.
--
paul-moore.com
^ permalink raw reply
* Re: [PATCH 03/61] ceph: Prefer IS_ERR_OR_NULL over manual NULL check
From: Viacheslav Dubeyko @ 2026-03-10 18:13 UTC (permalink / raw)
To: dm-devel@lists.linux.dev, phahn-oss@avm.de,
intel-wired-lan@lists.osuosl.org, linux-erofs@lists.ozlabs.org,
linux-security-module@vger.kernel.org, kvm@vger.kernel.org,
linux-sctp@vger.kernel.org, linux-pm@vger.kernel.org,
apparmor@lists.ubuntu.com, linux-ext4@vger.kernel.org,
amd-gfx@lists.freedesktop.org, linux-clk@vger.kernel.org,
linux-mips@vger.kernel.org, linux-media@vger.kernel.org,
netdev@vger.kernel.org, iommu@lists.linux.dev,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-usb@vger.kernel.org,
sched-ext@lists.linux.dev, linux-btrfs@vger.kernel.org,
linux-bluetooth@vger.kernel.org, linux-s390@vger.kernel.org,
samba-technical@lists.samba.org, intel-gfx@lists.freedesktop.org,
linux-trace-kernel@vger.kernel.org, ntfs3@lists.linux.dev,
linux-phy@lists.infradead.org, v9fs@lists.linux.dev,
ceph-devel@vger.kernel.org, tipc-discussion@lists.sourceforge.net,
linux-mtd@lists.infradead.org, linux-scsi@vger.kernel.org,
target-devel@vger.kernel.org, linux-gpio@vger.kernel.org,
cocci@inria.fr, linux-sh@vger.kernel.org,
linux-rockchip@lists.infradead.org,
linux-stm32@st-md-mailman.stormreply.com,
linux-cifs@vger.kernel.org, linux-modules@vger.kernel.org,
linux-sound@vger.kernel.org, bpf@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, linux-input@vger.kernel.org,
linux-leds@vger.kernel.org, dri-devel@lists.freedesktop.org,
linux-hyperv@vger.kernel.org, linux-mm@kvack.org,
linux-nfs@vger.kernel.org, gfs2@lists.linux.dev,
linux-wireless@vger.kernel.org, linux-omap@vger.kernel.org
Cc: idryomov@gmail.com, Alex Markuze, slava@dubeyko.com
In-Reply-To: <20260310-b4-is_err_or_null-v1-3-bd63b656022d@avm.de>
On Tue, 2026-03-10 at 12:48 +0100, Philipp Hahn wrote:
> Prefer using IS_ERR_OR_NULL() over using IS_ERR() and a manual NULL
> check.
>
> Change generated with coccinelle.
>
> To: Ilya Dryomov <idryomov@gmail.com>
> To: Alex Markuze <amarkuze@redhat.com>
> To: Viacheslav Dubeyko <slava@dubeyko.com>
> Cc: ceph-devel@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Philipp Hahn <phahn-oss@avm.de>
> ---
> fs/ceph/dir.c | 2 +-
> fs/ceph/snap.c | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
> index 86d7aa594ea99335af3e91a95c0a418fdc1b8a8a..934250748ae4fd4c148fd27bdf91175047c2877d 100644
> --- a/fs/ceph/dir.c
> +++ b/fs/ceph/dir.c
> @@ -889,7 +889,7 @@ int ceph_handle_notrace_create(struct inode *dir, struct dentry *dentry)
> {
> struct dentry *result = ceph_lookup(dir, dentry, 0);
>
> - if (result && !IS_ERR(result)) {
> + if (!IS_ERR_OR_NULL(result)) {
> /*
> * We created the item, then did a lookup, and found
> * it was already linked to another inode we already
> diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
> index 52b4c2684f922bfed39550311e793bfe3622cd26..528ad581be160713f91416115659e2dc6f259576 100644
> --- a/fs/ceph/snap.c
> +++ b/fs/ceph/snap.c
> @@ -902,7 +902,7 @@ int ceph_update_snap_trace(struct ceph_mds_client *mdsc,
> bad:
> err = -EIO;
> fail:
> - if (realm && !IS_ERR(realm))
> + if (!IS_ERR_OR_NULL(realm))
> ceph_put_snap_realm(mdsc, realm);
> if (first_realm)
> ceph_put_snap_realm(mdsc, first_realm);
Looks good.
Reviewed-by: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>
Thanks,
Slava.
^ permalink raw reply
* Re: [PATCH 0/3] Firmware LSM hook
From: Leon Romanovsky @ 2026-03-10 17:57 UTC (permalink / raw)
To: Stephen Smalley
Cc: Paul Moore, James Morris, Serge E. Hallyn, Jason Gunthorpe,
Saeed Mahameed, Itay Avraham, Dave Jiang, Jonathan Cameron,
linux-security-module, linux-kernel, linux-rdma, Chiara Meiohas,
Maher Sanalla, Edward Srouji
In-Reply-To: <CAEjxPJ4nTmovpgkzC+3=Oh7EAhpi1vHLwJfjezu-vzX_Q2OCug@mail.gmail.com>
On Tue, Mar 10, 2026 at 12:29:40PM -0400, Stephen Smalley wrote:
> On Tue, Mar 10, 2026 at 5:14 AM Leon Romanovsky <leon@kernel.org> wrote:
> > 1140 MLX5_SET(general_obj_in_cmd_hdr, cmd_in, uid, uid);
> > 1141 err = security_fw_validate_cmd(cmd_in, cmd_in_len, &dev->ib_dev.dev,
> > 1142 FW_CMD_CLASS_UVERBS, RDMA_DRIVER_MLX5);
> > 1143 if (err)
> > 1144 return err;
> > 1145
> > 1146 err = mlx5_cmd_do(dev->mdev, cmd_in, cmd_in_len, cmd_out, cmd_out_len);
> >
> > Could you point me to the LSM that would be best suited for performing
> > checks of this kind?
>
> If you just want to filter on opcodes, then the SELinux extended
> permissions (xperms) support may suffice, see:
> https://blog.siphos.be/2017/11/selinux-and-extended-permissions/
> https://kernsec.org/files/lss2015/vanderstoep.pdf
> https://github.com/SELinuxProject/selinux-notebook/blob/main/src/xperm_rules.md
>
> This was originally added to SELinux to support filtering ioctl
> commands and later extended to netlink as well.
>
> If you truly need/want filtering of arbitrary variable-length command
> buffers.
Yes. The opcode alone is not sufficient for any real‑world use.
It is not reliable because different firmware versions place different
parameters into the same mailbox entry under the same opcode.
Without inspecting the mailbox contents, you cannot properly filter them.
Thanks
^ permalink raw reply
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