* Re: [PATCH v5 18/23] bpf: Use vmalloc special flag
From: Edgecombe, Rick P @ 2025-08-12 18:49 UTC (permalink / raw)
To: glaubitz@physik.fu-berlin.de, peterz@infradead.org,
mingo@redhat.com, luto@kernel.org, bp@alien8.de
Cc: sam@gentoo.org, andreas@gaisler.com, nadav.amit@gmail.com,
anthony.yznaga@oracle.com, dave.hansen@linux.intel.com,
akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
linux_dti@icloud.com, will.deacon@arm.com,
deneen.t.dock@intel.com, linux-mm@kvack.org, tglx@linutronix.de,
linux-security-module@vger.kernel.org, sparclinux@vger.kernel.org,
hpa@zytor.com, linux-integrity@vger.kernel.org,
daniel@iogearbox.net, kernel-hardening@lists.openwall.com,
ast@kernel.org, x86@kernel.org, kristen@linux.intel.com
In-Reply-To: <49b112b80b211ae05b5f3c36a55f67041783f51e.camel@physik.fu-berlin.de>
On Tue, 2025-08-12 at 20:37 +0200, John Paul Adrian Glaubitz wrote:
> That could be true. I knew about the patch in [1] but I didn't think of applying it.
>
> FWIW, the crashes we're seeing on recent kernel versions look like this:
>
> [ 40.992851] \|/ ____ \|/
> [ 40.992851] "@'/ .. \`@"
> [ 40.992851] /_| \__/ |_\
> [ 40.992851] \__U_/
> [ 41.186220] (udev-worker)(88): Kernel illegal instruction [#1]
Possibly re-using some stale TLB executable VA which's page now has other data
in it.
> [ 41.262910] CPU: 0 UID: 0 PID: 88 Comm: (udev-worker) Tainted: G W 6.12.0+ #25
> [ 41.376151] Tainted: [W]=WARN
> [ 41.415025] TSTATE: 0000004411001607 TPC: 00000000101c21c0 TNPC: 00000000101c21c4 Y: 00000000 Tainted: G W
> [ 41.563717] TPC: <ehci_init_driver+0x0/0x160 [ehci_hcd]>
> [ 41.633584] g0: 00000000012005b8 g1: 00000000100a1800 g2: 0000000010206000 g3: 00000000101de000
> [ 41.747962] g4: fff000000a5af380 g5: 0000000000000000 g6: fff000000aac8000 g7: 0000000000000e7b
> [ 41.862338] o0: 0000000010060118 o1: 000000001020a000 o2: fff000000aa30ce0 o3: 0000000000000e7a
> [ 41.976728] o4: 00000000ff000000 o5: 00ff000000000000 sp: fff000000aacb091 ret_pc: 00000000101de028
> [ 42.095768] RPC: <ehci_pci_init+0x28/0x2000 [ehci_pci]>
> [ 42.164394] l0: 0000000000000000 l1: 0000000100043fff l2: ffffffffff800000 l3: 0000000000800000
> [ 42.278768] l4: fff00000001c8008 l5: 0000000000000000 l6: 00000000013358e0 l7: 0000000001002800
> [ 42.393143] i0: ffffffffffffffed i1: 00000000004db8d8 i2: 0000000000000000 i3: fff000000aa304e0
> [ 42.507517] i4: 0000000001127250 i5: 0000000010060000 i6: fff000000aacb141 i7: 0000000000427d90
> [ 42.621893] I7: <do_one_initcall+0x30/0x200>
> [ 42.677931] Call Trace:
> [ 42.709953] [<0000000000427d90>] do_one_initcall+0x30/0x200
> [ 42.783158] [<00000000004db908>] do_init_module+0x48/0x240
> [ 42.855214] [<00000000004dd82c>] load_module+0x19cc/0x1f20
> [ 42.927270] [<00000000004ddf8c>] init_module_from_file+0x6c/0xa0
> [ 43.006189] [<00000000004de1e4>] sys_finit_module+0x1c4/0x2c0
> [ 43.081677] [<0000000000406174>] linux_sparc_syscall+0x34/0x44
> [ 43.158307] Disabling lock debugging due to kernel taint
> [ 43.228077] Caller[0000000000427d90]: do_one_initcall+0x30/0x200
> [ 43.306995] Caller[00000000004db908]: do_init_module+0x48/0x240
> [ 43.384772] Caller[00000000004dd82c]: load_module+0x19cc/0x1f20
> [ 43.462544] Caller[00000000004ddf8c]: init_module_from_file+0x6c/0xa0
> [ 43.547184] Caller[00000000004de1e4]: sys_finit_module+0x1c4/0x2c0
> [ 43.628389] Caller[0000000000406174]: linux_sparc_syscall+0x34/0x44
> [ 43.710741] Caller[fff000010480e2fc]: 0xfff000010480e2fc
> [ 43.780508] Instruction DUMP:
> [ 43.780511] 00000000
> [ 43.819394] 00000000
> [ 43.850273] 00000000
> [ 43.881153] <00000000>
> [ 43.912036] 00000000
> [ 43.942917] 00000000
> [ 43.973797] 00000000
> [ 44.004678] 00000000
> [ 44.035561] 00000000
> [ 44.066443]
>
> Do you have any suggestion what to bisect?
This does look like kernel range TLB flush related. Not sure how it's related to
userspace huge pages. Perhaps the userspace range TLB flush has issues to? Or
the TLB flush asm needs to be fixed in this another sparc variant?
So far two issues were found with that patch and they were both rare
architectures with broken kernel TLB flushes. Kernel TLB flushes can actually
not be required for a long time, so probably the bug normally looked like
unexplained crashes after days. The VM_FLUSH_RESET_PERMS just made them show up
earlier in a bisectable way.
^ permalink raw reply
* Re: [PATCH v5 18/23] bpf: Use vmalloc special flag
From: John Paul Adrian Glaubitz @ 2025-08-12 18:59 UTC (permalink / raw)
To: Edgecombe, Rick P, peterz@infradead.org, mingo@redhat.com,
luto@kernel.org, bp@alien8.de
Cc: sam@gentoo.org, andreas@gaisler.com, nadav.amit@gmail.com,
anthony.yznaga@oracle.com, dave.hansen@linux.intel.com,
akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
linux_dti@icloud.com, will.deacon@arm.com, linux-mm@kvack.org,
tglx@linutronix.de, linux-security-module@vger.kernel.org,
sparclinux@vger.kernel.org, hpa@zytor.com,
linux-integrity@vger.kernel.org, daniel@iogearbox.net,
kernel-hardening@lists.openwall.com, ast@kernel.org,
x86@kernel.org, kristen@linux.intel.com
In-Reply-To: <7e4dfc01e132196d3ff10df18622252a8455d1b8.camel@intel.com>
On Tue, 2025-08-12 at 18:49 +0000, Edgecombe, Rick P wrote:
> On Tue, 2025-08-12 at 20:37 +0200, John Paul Adrian Glaubitz wrote:
> > That could be true. I knew about the patch in [1] but I didn't think of applying it.
> >
> > FWIW, the crashes we're seeing on recent kernel versions look like this:
> >
> > [ 40.992851] \|/ ____ \|/
> > [ 40.992851] "@'/ .. \`@"
> > [ 40.992851] /_| \__/ |_\
> > [ 40.992851] \__U_/
> > [ 41.186220] (udev-worker)(88): Kernel illegal instruction [#1]
>
> Possibly re-using some stale TLB executable VA which's page now has other data
> in it.
Makes sense given the memory is actually zero'd out.
> > [ 41.262910] CPU: 0 UID: 0 PID: 88 Comm: (udev-worker) Tainted: G W 6.12.0+ #25
> > [ 41.376151] Tainted: [W]=WARN
> > [ 41.415025] TSTATE: 0000004411001607 TPC: 00000000101c21c0 TNPC: 00000000101c21c4 Y: 00000000 Tainted: G W
> > [ 41.563717] TPC: <ehci_init_driver+0x0/0x160 [ehci_hcd]>
> > [ 41.633584] g0: 00000000012005b8 g1: 00000000100a1800 g2: 0000000010206000 g3: 00000000101de000
> > [ 41.747962] g4: fff000000a5af380 g5: 0000000000000000 g6: fff000000aac8000 g7: 0000000000000e7b
> > [ 41.862338] o0: 0000000010060118 o1: 000000001020a000 o2: fff000000aa30ce0 o3: 0000000000000e7a
> > [ 41.976728] o4: 00000000ff000000 o5: 00ff000000000000 sp: fff000000aacb091 ret_pc: 00000000101de028
> > [ 42.095768] RPC: <ehci_pci_init+0x28/0x2000 [ehci_pci]>
> > [ 42.164394] l0: 0000000000000000 l1: 0000000100043fff l2: ffffffffff800000 l3: 0000000000800000
> > [ 42.278768] l4: fff00000001c8008 l5: 0000000000000000 l6: 00000000013358e0 l7: 0000000001002800
> > [ 42.393143] i0: ffffffffffffffed i1: 00000000004db8d8 i2: 0000000000000000 i3: fff000000aa304e0
> > [ 42.507517] i4: 0000000001127250 i5: 0000000010060000 i6: fff000000aacb141 i7: 0000000000427d90
> > [ 42.621893] I7: <do_one_initcall+0x30/0x200>
> > [ 42.677931] Call Trace:
> > [ 42.709953] [<0000000000427d90>] do_one_initcall+0x30/0x200
> > [ 42.783158] [<00000000004db908>] do_init_module+0x48/0x240
> > [ 42.855214] [<00000000004dd82c>] load_module+0x19cc/0x1f20
> > [ 42.927270] [<00000000004ddf8c>] init_module_from_file+0x6c/0xa0
> > [ 43.006189] [<00000000004de1e4>] sys_finit_module+0x1c4/0x2c0
> > [ 43.081677] [<0000000000406174>] linux_sparc_syscall+0x34/0x44
> > [ 43.158307] Disabling lock debugging due to kernel taint
> > [ 43.228077] Caller[0000000000427d90]: do_one_initcall+0x30/0x200
> > [ 43.306995] Caller[00000000004db908]: do_init_module+0x48/0x240
> > [ 43.384772] Caller[00000000004dd82c]: load_module+0x19cc/0x1f20
> > [ 43.462544] Caller[00000000004ddf8c]: init_module_from_file+0x6c/0xa0
> > [ 43.547184] Caller[00000000004de1e4]: sys_finit_module+0x1c4/0x2c0
> > [ 43.628389] Caller[0000000000406174]: linux_sparc_syscall+0x34/0x44
> > [ 43.710741] Caller[fff000010480e2fc]: 0xfff000010480e2fc
> > [ 43.780508] Instruction DUMP:
> > [ 43.780511] 00000000
> > [ 43.819394] 00000000
> > [ 43.850273] 00000000
> > [ 43.881153] <00000000>
> > [ 43.912036] 00000000
> > [ 43.942917] 00000000
> > [ 43.973797] 00000000
> > [ 44.004678] 00000000
> > [ 44.035561] 00000000
> > [ 44.066443]
> >
> > Do you have any suggestion what to bisect?
>
> This does look like kernel range TLB flush related. Not sure how it's related to
> userspace huge pages. Perhaps the userspace range TLB flush has issues to? Or
> the TLB flush asm needs to be fixed in this another sparc variant?
The patch you previously linked actually fixed this particular SPARC variant which
is sun4u, i.e. the non-hypervisor variant with sun4v being the hypervisor one.
I was already thinking that the fix in d3c976c14ad8 was possible incomplete.
> So far two issues were found with that patch and they were both rare
> architectures with broken kernel TLB flushes. Kernel TLB flushes can actually
> not be required for a long time, so probably the bug normally looked like
> unexplained crashes after days. The VM_FLUSH_RESET_PERMS just made them show up
> earlier in a bisectable way.
Yeah, I think that could actually be the case.
I wonder whether I can revert both d3c976c14ad8 and a74ad5e660a9 on a current
tree and see if that fixes the bug.
Adrian
--
.''`. John Paul Adrian Glaubitz
: :' : Debian Developer
`. `' Physicist
`- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913
^ permalink raw reply
* Re: [RFC PATCH 0/6] fs/9p: Reuse inode based on path (in addition to qid)
From: Tingmao Wang @ 2025-08-12 23:53 UTC (permalink / raw)
To: Dominique Martinet, Christian Schoenebeck
Cc: Eric Van Hensbergen, Latchesar Ionkov, v9fs,
Mickaël Salaün, Günther Noack,
linux-security-module, Jan Kara, Amir Goldstein,
Matthew Bobrowski, Al Viro, linux-fsdevel
In-Reply-To: <13395769.lPas3JvW2k@silver>
On 8/8/25 11:27, Dominique Martinet wrote:
> Sorry for the delay...
No worries, thanks for picking this up!
>
> Tingmao Wang wrote on Sun, Apr 06, 2025 at 09:43:01PM +0100:
>> Unrelated to the above problem, it also seems like even with the revert in
>> [2], because in cached mode inode are still reused based on qid (and type,
>> version (aka mtime), etc), the setup mentioned in [2] still causes
>> problems in th latest kernel with cache=loose:
>
> cache=loose is "you're on your own", I think it's fine to keep as is,
> especially given qemu can handle it with multidevs=remap if required
On 8/8/25 11:52, Christian Schoenebeck wrote:
>> [...]
>
> As of QEMU 10.0, multidevs=remap (i.e. remapping inodes from host to guest) is
> now the default behaviour, since inode collisions were constantly causing
> issues and confusion among 9p users.
>
> And yeah, cache=loose means 9p client is blind for whatever changes on 9p
> server side.
>
> /Christian
>
My understanding of cache=loose was that it only assumes that the server
side can't change the fs under the client, but otherwise things like
inodes should work identically, even though currently it works differently
due to (only) cached mode re-using inodes - was this deliberate?
Basically, assuming no unexpected server side changes, I would think that
the user would not be totally "on their own" (even if there are colliding
qids). But given the issue with breaking how hardlinks currently works in
cached mode, as Dominique mentioned below, and the fact that inode
collisions should be rare given the new QEMU default, maybe we do need to
handle this differently (i.e. keep the existing behaviour and working
hardlinks for cached mode)? I'm happy either way (Landlock already works
currently with cached mode)
On 8/8/25 11:27, Dominique Martinet wrote:
> Tingmao Wang wrote on Sun, Apr 06, 2025 at 09:43:01PM +0100:
> [...]
>> With the above in mind, I have a proposal for 9pfs to:
>> 1. Reuse inodes even in uncached mode
>> 2. However, reuse them based on qid.path AND the actual pathname, by doing
>> the appropriate testing in v9fs_test(_new)?_inode(_dotl)?
>
> I think that's fine for cache=none, but it breaks hardlinks on
> cache=loose so I think this ought to only be done without cache
> (I haven't really played with the cache flag bits, not check pathname if
> any of loose, writeback or metadata are set?)
>
I think currently 9pfs reuse inodes if cache is either loose or metadata
(but not writeback), given:
else if (v9ses->cache & (CACHE_META|CACHE_LOOSE))
inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb);
else
inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
in v9fs_vfs_lookup, so maybe we keep this pattern and not check pathname
if (loose|metadata) is set (but not writeback)?
>> The main problem here is how to store the pathname in a sensible way and
>> tie it to the inode. For now I opted with an array of names acquired with
>> take_dentry_name_snapshot, which reuses the same memory as the dcache to
>> store the actual strings
(Self correction: technically, the space is only shared if they are long
enough to not be inlined, which is DNAME_INLINE_LEN = 40 for 64bit or 20
for 32bit, so in most cases the names would probably be copied. Maybe it
would be more compact in terms of memory usage to just store the path as a
string, with '/' separating components? But then the code would be more
complex and we can't easily use d_same_name anymore, so maybe it's not
worth doing, unless this will prove useful for other purposes, like the
re-opening of fid mentioned below?)
>> , but doesn't tie the lifetime of the dentry with
>> the inode (I thought about holding a reference to the dentry in the
>> v9fs_inode, but it seemed like a wrong approach and would cause dentries
>> to not be evicted/released).
>
> That's pretty hard to get right and I wish we had more robust testing
> there... But I guess that's appropriate enough.
>
> I know Atos has done an implementation that keeps the full path
> somewhere to re-open fids in case of server reconnections, but that code
> has never been submitted upstream that I can see so I can't check how
> they used to store the path :/ Ohwell.
>
>> Storing one pathname per inode also means we don't reuse the same inode
>> for hardlinks -- maybe this can be fixed as well in a future version, if
>> this approach sounds good?
>
> Ah, you pointed it out yourself. I don't see how we could fix that, as
> we have no way other than the qid to identify hard links; so this really
> ought to depend on cache level if you want to support landlock/*notify
> in cache=none.
In that case, and as discussed above, I'm happy to change this patch
series to only affect uncached.
>
> Frankly the *notify use-case is difficult to support properly, as files
> can change from under us (e.g. modifying the file directly on the host
> in qemu case, or just multiple mounts of the same directory), so it
> can't be relied on in the general case anyway -- 9p doesn't have
> anything like NFSv4 leases to get notified when other clients write a
> file we "own", so whatever we do will always be limited...
> But I guess it can make sense for limited monitoring e.g. rebuilding
> something on change and things like that?
One of the first use case I can think of here is IDE/code editors
reloading state (e.g. the file tree) on change, which I think didn't work
for 9pfs folders opened with vscode if I remembered correctly (but I
haven't tested this recently). Even though we can't monitor for remote
changes, having this work for local changes would still be nice.
Note that aside from Mickaël's comments which I will apply in the next
version, I also realized that I haven't done the proper handling for
renames (it should probably update the v9fs_ino_path in the renamed
inode). I will do that in the next version (in addition to changing the
cached behaviour). Do let me know if you have any other comment on the
patch series.
Best,
Tingmao
^ permalink raw reply
* Re: [RFC PATCH 1/6] fs/9p: Add ability to identify inode by path for .L
From: Tingmao Wang @ 2025-08-12 23:57 UTC (permalink / raw)
To: Mickaël Salaün, Dominique Martinet
Cc: Al Viro, Eric Van Hensbergen, Latchesar Ionkov,
Christian Schoenebeck, v9fs, Günther Noack,
linux-security-module, Jan Kara, Amir Goldstein,
Matthew Bobrowski, linux-fsdevel
In-Reply-To: <20250808.oog4xee5Pee2@digikod.net>
Thanks for the review :) I will try to send a v2 in the coming weeks with
the two changes you suggested and the changes to cached mode as suggested
by Dominique (plus rename handling). (will also try to figure out how to
test with xfstests)
On 8/8/25 09:32, Mickaël Salaün wrote:
> [...]
>> On 7/5/25 01:25, Al Viro wrote:
>>> On Sun, Apr 06, 2025 at 09:43:02PM +0100, Tingmao Wang wrote:
>>>> +bool ino_path_compare(struct v9fs_ino_path *ino_path,
>>>> + struct dentry *dentry)
>>>> +{
>>>> + struct dentry *curr = dentry;
>>>> + struct qstr *curr_name;
>>>> + struct name_snapshot *compare;
>>>> + ssize_t i;
>>>> +
>>>> + lockdep_assert_held_read(&v9fs_dentry2v9ses(dentry)->rename_sem);
>>>> +
>>>> + rcu_read_lock();
>>>> + for (i = ino_path->nr_components - 1; i >= 0; i--) {
>>>> + if (curr->d_parent == curr) {
>>>> + /* We're supposed to have more components to walk */
>>>> + rcu_read_unlock();
>>>> + return false;
>>>> + }
>>>> + curr_name = &curr->d_name;
>>>> + compare = &ino_path->names[i];
>>>> + /*
>>>> + * We can't use hash_len because it is salted with the parent
>>>> + * dentry pointer. We could make this faster by pre-computing our
>>>> + * own hashlen for compare and ino_path outside, probably.
>>>> + */
>>>> + if (curr_name->len != compare->name.len) {
>>>> + rcu_read_unlock();
>>>> + return false;
>>>> + }
>>>> + if (strncmp(curr_name->name, compare->name.name,
>>>> + curr_name->len) != 0) {
>>>
>>> ... without any kind of protection for curr_name. Incidentally,
>>> what about rename()? Not a cross-directory one, just one that
>>> changes the name of a subdirectory within the same parent?
>>
>> As far as I can tell, in v9fs_vfs_rename, v9ses->rename_sem is taken for
>> both same-parent and different parent renames, so I think we're safe here
>> (and hopefully for any v9fs dentries, nobody should be causing d_name to
>> change except for ourselves when we call d_move in v9fs_vfs_rename? If
>> yes then because we also take v9ses->rename_sem, in theory we should be
>> fine here...?)
>
> A lockdep_assert_held() or similar and a comment would make this clear.
I can add a comment, but there is already a lockdep_assert_held_read of
the v9fs rename sem at the top of this function.
> [...]
>> /*
>> * Must hold rename_sem due to traversing parents
>> */
>> bool ino_path_compare(struct v9fs_ino_path *ino_path, struct dentry *dentry)
>> {
>> struct dentry *curr = dentry;
>> struct name_snapshot *compare;
>> ssize_t i;
>>
>> lockdep_assert_held_read(&v9fs_dentry2v9ses(dentry)->rename_sem);
>>
>> rcu_read_lock();
>> for (i = ino_path->nr_components - 1; i >= 0; i--) {
>> if (curr->d_parent == curr) {
>> /* We're supposed to have more components to walk */
>> rcu_read_unlock();
>> return false;
>> }
>> compare = &ino_path->names[i];
>> if (!d_same_name(curr, curr->d_parent, &compare->name)) {
>> rcu_read_unlock();
>> return false;
>> }
>> curr = curr->d_parent;
>> }
>> rcu_read_unlock();
>> if (curr != curr->d_parent) {
Looking at this again I think this check probably needs to be done inside
RCU, will fix as below:
>> /* dentry is deeper than ino_path */
>> return false;
>> }
>> return true;
>> }
diff --git a/fs/9p/ino_path.c b/fs/9p/ino_path.c
index 0000b4964df0..7264003cb087 100644
--- a/fs/9p/ino_path.c
+++ b/fs/9p/ino_path.c
@@ -77,13 +77,15 @@ void free_ino_path(struct v9fs_ino_path *path)
}
/*
- * Must hold rename_sem due to traversing parents
+ * Must hold rename_sem due to traversing parents. Returns whether
+ * ino_path matches with the path of a v9fs dentry.
*/
bool ino_path_compare(struct v9fs_ino_path *ino_path, struct dentry *dentry)
{
struct dentry *curr = dentry;
struct name_snapshot *compare;
ssize_t i;
+ bool ret;
lockdep_assert_held_read(&v9fs_dentry2v9ses(dentry)->rename_sem);
@@ -101,10 +103,8 @@ bool ino_path_compare(struct v9fs_ino_path *ino_path, struct dentry *dentry)
}
curr = curr->d_parent;
}
+ /* Comparison fails if dentry is deeper than ino_path */
+ ret = (curr == curr->d_parent);
rcu_read_unlock();
- if (curr != curr->d_parent) {
- /* dentry is deeper than ino_path */
- return false;
- }
- return true;
+ return ret;
}
>
> I like this new version.
>
^ permalink raw reply related
* Re: [PATCH v2 08/13] bpf: Implement signature verification for BPF programs
From: Paul Moore @ 2025-08-13 2:20 UTC (permalink / raw)
To: Blaise Boscaccy, KP Singh
Cc: bpf, linux-security-module, kys, ast, daniel, andrii,
James.Bottomley, wufan
In-Reply-To: <87sei58vy3.fsf@microsoft.com>
On Tue, Aug 5, 2025 at 2:28 PM Blaise Boscaccy
<bboscaccy@linux.microsoft.com> wrote:
> KP Singh <kpsingh@kernel.org> writes:
> > This patch extends the BPF_PROG_LOAD command by adding three new fields
> > to `union bpf_attr` in the user-space API:
> >
> > - signature: A pointer to the signature blob.
> > - signature_size: The size of the signature blob.
> > - keyring_id: The serial number of a loaded kernel keyring (e.g.,
> > the user or session keyring) containing the trusted public keys.
> >
> > When a BPF program is loaded with a signature, the kernel:
> >
> > 1. Retrieves the trusted keyring using the provided `keyring_id`.
> > 2. Verifies the supplied signature against the BPF program's
> > instruction buffer.
> > 3. If the signature is valid and was generated by a key in the trusted
> > keyring, the program load proceeds.
> > 4. If no signature is provided, the load proceeds as before, allowing
> > for backward compatibility. LSMs can chose to restrict unsigned
> > programs and implement a security policy.
> > 5. If signature verification fails for any reason,
> > the program is not loaded.
> [...]
>
> The following is what we propose to build on top of this to implement
> in-kernel hash chain verification. This allows for signature
> verification of arbitrary maps and isn't coupled to light-skeletons or
> any specific implementation.
>
>
> From: Blaise Boscaccy <bboscaccy@linux.microsoft.com>
> Date: Mon, 28 Jul 2025 08:14:57 -0700
> Subject: bpf: Add hash chain signature support for arbitrary maps
>
> This patch introduces hash chain support for signature verification of
> arbitrary bpf map objects which was described here:
> https://lore.kernel.org/linux-security-module/20250721211958.1881379-1-kpsingh@kernel.org/
>
> The UAPI is extended to allow for in-kernel checking of maps passed in
> via the fd_array. A hash chain is constructed from the maps, in order
> specified by the signature_maps field. The hash chain is terminated
> with the hash of the program itself.
>
> Signed-off-by: Blaise Boscaccy <bboscaccy@linux.microsoft.com>
> ---
> include/uapi/linux/bpf.h | 6 +++
> kernel/bpf/syscall.c | 75 ++++++++++++++++++++++++++++++++--
> tools/include/uapi/linux/bpf.h | 6 +++
> 3 files changed, 83 insertions(+), 4 deletions(-)
Some minor comments below, but in general I think this approach is
good in that it preserves the signature scheme in KP's patchset while
also supporting a scheme that is not reliant on the lskel or
verification, with the user loading the program/lskel choosing which
signature scheme to use. Unless something has changed since we've
discussed this last, I believe this should provide the basic BPF
infrastructure needed to satisfy all the different requirements
already described.
Thoughts on this KP (as well as any others who have been following along)?
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 10fd3ea5d91fd..f7e9bcabd9dcc 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -2780,15 +2780,36 @@ static bool is_perfmon_prog_type(enum bpf_prog_type prog_type)
> }
> }
>
> +static inline int bpf_map_get_hash(int map_fd, void *buffer)
> +{
> + struct bpf_map *map;
> +
> + CLASS(fd, f)(map_fd);
> + map = __bpf_map_get(f);
> + if (IS_ERR(map))
> + return PTR_ERR(map);
> +
> + if (!map->ops->map_get_hash)
> + return -EINVAL;
> +
> + return map->ops->map_get_hash(map, SHA256_DIGEST_SIZE, buffer);
> +}
It would be nice to see some agility on the hash algorithm, but it's
probably not critical for a first effort. I can easily see an
algorithm field being added to bpf_attr, using the same digest
algorithm as specified in the PKCS7 signature, or something else
sufficiently clever.
> static noinline int bpf_prog_verify_signature(struct bpf_prog *prog,
> union bpf_attr *attr,
> bool is_kernel)
> {
> bpfptr_t usig = make_bpfptr(attr->signature, is_kernel);
> - struct bpf_dynptr_kern sig_ptr, insns_ptr;
> + bpfptr_t umaps;
> + struct bpf_dynptr_kern sig_ptr, insns_ptr, hash_ptr;
> struct bpf_key *key = NULL;
> void *sig;
> + int *maps;
> + int map_fd;
> int err = 0;
> + u64 buffer[8];
> + u64 hash[4];
It would be good to replace the magic numbers above with something
that is a bit more self documenting, e.g. 'u64 hash[SHA256_DIGEST_SIZE
/ sizeof(u64)]'. The same goes for some of the pointer offset math
below, assuming the result isn't too ugly. If the resulting code is
pretty awful to look at, a quick comment or two might be a good idea.
> + int n;
>
> if (system_keyring_id_check(attr->keyring_id) == 0)
> key = bpf_lookup_system_key(attr->keyring_id);
> @@ -2808,16 +2829,62 @@ static noinline int bpf_prog_verify_signature(struct bpf_prog *prog,
> bpf_dynptr_init(&insns_ptr, prog->insnsi, BPF_DYNPTR_TYPE_LOCAL, 0,
> prog->len * sizeof(struct bpf_insn));
>
> - err = bpf_verify_pkcs7_signature((struct bpf_dynptr *)&insns_ptr,
> - (struct bpf_dynptr *)&sig_ptr, key);
> + if (!attr->signature_maps_size) {
> + err = bpf_verify_pkcs7_signature((struct bpf_dynptr *)&insns_ptr,
> + (struct bpf_dynptr *)&sig_ptr, key);
> + } else {
> + bpf_dynptr_init(&hash_ptr, hash, BPF_DYNPTR_TYPE_LOCAL, 0,
> + sizeof(hash));
> + umaps = make_bpfptr(attr->signature_maps, is_kernel);
> + maps = kvmemdup_bpfptr(umaps, attr->signature_maps_size * sizeof(*maps));
> + if (!maps) {
> + err = -ENOMEM;
> + goto out;
> + }
> + n = attr->signature_maps_size - 1;
> + err = copy_from_bpfptr_offset(&map_fd, make_bpfptr(attr->fd_array, is_kernel),
> + maps[n] * sizeof(map_fd),
> + sizeof(map_fd));
> + if (err < 0)
> + goto free_maps;
> +
> + err = bpf_map_get_hash(map_fd, hash);
> + if (err != 0)
> + goto free_maps;
> +
> + n--;
> + while (n >= 0) {
> + memcpy(buffer, hash, sizeof(hash));
> + err = copy_from_bpfptr_offset(&map_fd,
> + make_bpfptr(attr->fd_array, is_kernel),
> + maps[n] * sizeof(map_fd),
> + sizeof(map_fd));
> + if (err < 0)
> + goto free_maps;
> +
> + err = bpf_map_get_hash(map_fd, buffer+4);
> + if (err != 0)
> + goto free_maps;
> + sha256((u8 *)buffer, sizeof(buffer), (u8 *)&hash);
> + n--;
> + }
> + sha256((u8 *)prog->insnsi, prog->len * sizeof(struct bpf_insn), (u8 *)&buffer);
> + memcpy(buffer+4, hash, sizeof(hash));
> + sha256((u8 *)buffer, sizeof(buffer), (u8 *)&hash);
> + err = bpf_verify_pkcs7_signature((struct bpf_dynptr *)&hash_ptr,
> + (struct bpf_dynptr *)&sig_ptr, key);
>
> +free_maps:
> + kvfree(maps);
> + }
> +out:
> bpf_key_put(key);
> kvfree(sig);
> return err;
> }
>
> /* last field in 'union bpf_attr' used by this command */
> -#define BPF_PROG_LOAD_LAST_FIELD keyring_id
> +#define BPF_PROG_LOAD_LAST_FIELD signature_maps_size
>
> static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size)
> {
--
paul-moore.com
^ permalink raw reply
* Re: [RFC PATCH 0/6] fs/9p: Reuse inode based on path (in addition to qid)
From: Dominique Martinet @ 2025-08-13 5:30 UTC (permalink / raw)
To: Tingmao Wang
Cc: Christian Schoenebeck, Eric Van Hensbergen, Latchesar Ionkov,
v9fs, Mickaël Salaün, Günther Noack,
linux-security-module, Jan Kara, Amir Goldstein,
Matthew Bobrowski, Al Viro, linux-fsdevel
In-Reply-To: <b9aa9f6f-483f-41a5-a8d7-a3126d7e4b8f@maowtm.org>
Tingmao Wang wrote on Wed, Aug 13, 2025 at 12:53:37AM +0100:
> My understanding of cache=loose was that it only assumes that the server
> side can't change the fs under the client, but otherwise things like
> inodes should work identically, even though currently it works differently
> due to (only) cached mode re-using inodes - was this deliberate?
Right, generally speaking I agree things should work as long as the
mount is exclusive (can't change server side/no other client); but
I think it's fine to extend this to server being "sane" (as in,
protocol-wise we're supposed to be guaranteed that two files are
identical if and only if qid is identical)
> > I think that's fine for cache=none, but it breaks hardlinks on
> > cache=loose so I think this ought to only be done without cache
> > (I haven't really played with the cache flag bits, not check pathname if
> > any of loose, writeback or metadata are set?)
>
> I think currently 9pfs reuse inodes if cache is either loose or metadata
> (but not writeback), given:
>
> else if (v9ses->cache & (CACHE_META|CACHE_LOOSE))
> inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb);
> else
> inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
>
> in v9fs_vfs_lookup, so maybe we keep this pattern and not check pathname
> if (loose|metadata) is set (but not writeback)?
This makes sense, let's stick to loose/metadata for this as well.
> >> The main problem here is how to store the pathname in a sensible way and
> >> tie it to the inode. For now I opted with an array of names acquired with
> >> take_dentry_name_snapshot, which reuses the same memory as the dcache to
> >> store the actual strings
>
> (Self correction: technically, the space is only shared if they are long
> enough to not be inlined, which is DNAME_INLINE_LEN = 40 for 64bit or 20
> for 32bit, so in most cases the names would probably be copied. Maybe it
> would be more compact in terms of memory usage to just store the path as a
> string, with '/' separating components? But then the code would be more
> complex and we can't easily use d_same_name anymore, so maybe it's not
> worth doing, unless this will prove useful for other purposes, like the
> re-opening of fid mentioned below?)
I think it's better to keep things simple first and check the actual
impact with a couple of simple benchmarks (re-opening a file in a loop
with cache=none should hit this path?)
If we want to improve this, rather than keeping the full string it might
make sense to carry a partial hash in each dentry so we can get away
with checking only the parent's dentry + current dentry, or something
like that?
But, simple and working is better than fast and broken, so let's have a
simple v1 first.
> > Frankly the *notify use-case is difficult to support properly, as files
> > can change from under us (e.g. modifying the file directly on the host
> > in qemu case, or just multiple mounts of the same directory), so it
> > can't be relied on in the general case anyway -- 9p doesn't have
> > anything like NFSv4 leases to get notified when other clients write a
> > file we "own", so whatever we do will always be limited...
> > But I guess it can make sense for limited monitoring e.g. rebuilding
> > something on change and things like that?
>
> One of the first use case I can think of here is IDE/code editors
> reloading state (e.g. the file tree) on change, which I think didn't work
> for 9pfs folders opened with vscode if I remembered correctly (but I
> haven't tested this recently). Even though we can't monitor for remote
> changes, having this work for local changes would still be nice.
Yeah, I also do this manually with entr[1], and git's fsmonitor (with
watchman) does that too -- so I guess people living in a 9p mount would
see it..
[1] https://github.com/eradman/entr
But I think 9p is just slow in general so such setups can probably be
improved more drastically by using something else :P
Anyway, thank you for your time/work, I'll try to be more timely in
later reviews.
--
Dominique Martinet | Asmadeus
^ permalink raw reply
* Re: [PATCH RFC V10 4/7] KVM: guest_memfd: Use guest mem inodes instead of anonymous inodes
From: Garg, Shivank @ 2025-08-13 5:37 UTC (permalink / raw)
To: Ackerley Tng, David Hildenbrand, seanjc, vbabka, willy, akpm,
shuah, pbonzini, brauner, viro
Cc: paul, jmorris, serge, pvorel, bfoster, tabba, vannapurve,
chao.gao, bharata, nikunj, michael.day, shdhiman, yan.y.zhao,
Neeraj.Upadhyay, thomas.lendacky, michael.roth, aik, jgg,
kalyazin, peterx, jack, rppt, hch, cgzones, ira.weiny, rientjes,
roypat, ziy, matthew.brost, joshua.hahnjy, rakie.kim, byungchul,
gourry, kent.overstreet, ying.huang, apopple, chao.p.peng, amit,
ddutile, dan.j.williams, ashish.kalra, gshan, jgowans,
pankaj.gupta, papaluri, yuzhao, suzuki.poulose, quic_eberman,
aneeshkumar.kizhakeveetil, linux-fsdevel, linux-mm, linux-kernel,
linux-security-module, kvm, linux-kselftest, linux-coco
In-Reply-To: <diqz8qjpzh6s.fsf@ackerleytng-ctop.c.googlers.com>
On 8/12/2025 2:53 AM, Ackerley Tng wrote:
> David Hildenbrand <david@redhat.com> writes:
>
>> On 11.08.25 11:06, Shivank Garg wrote:
>>> From: Ackerley Tng <ackerleytng@google.com>
>>>
>>> [...snip...]
>>>
>>> +static struct file *kvm_gmem_inode_create_getfile(void *priv, loff_t size,
>>> + u64 flags)
>>> +{
>>> + static const char *name = "[kvm-gmem]";
>>> + struct inode *inode;
>>> + struct file *file;
>>> + int err;
>>> +
>>> + err = -ENOENT;
>>
>> Maybe add a comment here when the module reference will get
>> dropped. And maybe we should just switch to fops_get() + fops_put?
>>
>> /* __fput() will take care of fops_put(). */
>> if (!fops_get(&kvm_gmem_fops))
>> goto err;
>>
>
> Sounds good! Please see attached patch. It's exactly what you suggested
> except I renamed the goto target to err_fops_put:
>
>>> +
>>> + inode = kvm_gmem_inode_make_secure_inode(name, size, flags);
>>> + if (IS_ERR(inode)) {
>>> + err = PTR_ERR(inode);
>>> + goto err_put_module;
>>> + }
>>> +
>>> + file = alloc_file_pseudo(inode, kvm_gmem_mnt, name, O_RDWR,
>>> + &kvm_gmem_fops);
>>> + if (IS_ERR(file)) {
>>> + err = PTR_ERR(file);
>>> + goto err_put_inode;
>>> + }
>>> +
>>> + file->f_flags |= O_LARGEFILE;
>>> + file->private_data = priv;
>>> +
>>> +out:
>>> + return file;
>>> +
>>> +err_put_inode:
>>> + iput(inode);
>>> +err_put_module:
>>> + module_put(kvm_gmem_fops.owner);
>>
>> fops_put(&kvm_gmem_fops);
>>
>> ?
>>
>>
>> Acked-by: David Hildenbrand <david@redhat.com>
>>
>> --
>> Cheers,
>>
>> David / dhildenb
>
> From f2bd4499bce4db69bf34be75e009579db4329b7c Mon Sep 17 00:00:00 2001
> From: Ackerley Tng <ackerleytng@google.com>
> Date: Sun, 13 Jul 2025 17:43:35 +0000
> Subject: [PATCH] KVM: guest_memfd: Use guest mem inodes instead of anonymous
> inodes
>
> guest_memfd's inode represents memory the guest_memfd is
> providing. guest_memfd's file represents a struct kvm's view of that
> memory.
>
> Using a custom inode allows customization of the inode teardown
> process via callbacks. For example, ->evict_inode() allows
> customization of the truncation process on file close, and
> ->destroy_inode() and ->free_inode() allow customization of the inode
> freeing process.
>
> Customizing the truncation process allows flexibility in management of
> guest_memfd memory and customization of the inode freeing process
> allows proper cleanup of memory metadata stored on the inode.
>
> Memory metadata is more appropriately stored on the inode (as opposed
> to the file), since the metadata is for the memory and is not unique
> to a specific binding and struct kvm.
>
> Co-developed-by: Fuad Tabba <tabba@google.com>
> Signed-off-by: Fuad Tabba <tabba@google.com>
> Signed-off-by: Shivank Garg <shivankg@amd.com>
> Signed-off-by: Ackerley Tng <ackerleytng@google.com>
> ---
> include/uapi/linux/magic.h | 1 +
> virt/kvm/guest_memfd.c | 129 ++++++++++++++++++++++++++++++-------
> virt/kvm/kvm_main.c | 7 +-
> virt/kvm/kvm_mm.h | 9 +--
> 4 files changed, 119 insertions(+), 27 deletions(-)
>
> diff --git a/include/uapi/linux/magic.h b/include/uapi/linux/magic.h
> index bb575f3ab45e5..638ca21b7a909 100644
> --- a/include/uapi/linux/magic.h
> +++ b/include/uapi/linux/magic.h
> @@ -103,5 +103,6 @@
> #define DEVMEM_MAGIC 0x454d444d /* "DMEM" */
> #define SECRETMEM_MAGIC 0x5345434d /* "SECM" */
> #define PID_FS_MAGIC 0x50494446 /* "PIDF" */
> +#define GUEST_MEMFD_MAGIC 0x474d454d /* "GMEM" */
>
> #endif /* __LINUX_MAGIC_H__ */
> diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
> index 08a6bc7d25b60..6c66a09740550 100644
> --- a/virt/kvm/guest_memfd.c
> +++ b/virt/kvm/guest_memfd.c
> @@ -1,12 +1,16 @@
> // SPDX-License-Identifier: GPL-2.0
> +#include <linux/anon_inodes.h>
> #include <linux/backing-dev.h>
> #include <linux/falloc.h>
> +#include <linux/fs.h>
> #include <linux/kvm_host.h>
> +#include <linux/pseudo_fs.h>
> #include <linux/pagemap.h>
> -#include <linux/anon_inodes.h>
>
> #include "kvm_mm.h"
>
> +static struct vfsmount *kvm_gmem_mnt;
> +
> struct kvm_gmem {
> struct kvm *kvm;
> struct xarray bindings;
> @@ -385,9 +389,45 @@ static struct file_operations kvm_gmem_fops = {
> .fallocate = kvm_gmem_fallocate,
> };
>
> -void kvm_gmem_init(struct module *module)
> +static int kvm_gmem_init_fs_context(struct fs_context *fc)
> +{
> + if (!init_pseudo(fc, GUEST_MEMFD_MAGIC))
> + return -ENOMEM;
> +
> + fc->s_iflags |= SB_I_NOEXEC;
> + fc->s_iflags |= SB_I_NODEV;
> +
> + return 0;
> +}
> +
> +static struct file_system_type kvm_gmem_fs = {
> + .name = "guest_memfd",
> + .init_fs_context = kvm_gmem_init_fs_context,
> + .kill_sb = kill_anon_super,
> +};
> +
> +static int kvm_gmem_init_mount(void)
> +{
> + kvm_gmem_mnt = kern_mount(&kvm_gmem_fs);
> +
> + if (IS_ERR(kvm_gmem_mnt))
> + return PTR_ERR(kvm_gmem_mnt);
> +
> + kvm_gmem_mnt->mnt_flags |= MNT_NOEXEC;
> + return 0;
> +}
> +
> +int kvm_gmem_init(struct module *module)
> {
> kvm_gmem_fops.owner = module;
> +
> + return kvm_gmem_init_mount();
> +}
> +
> +void kvm_gmem_exit(void)
> +{
> + kern_unmount(kvm_gmem_mnt);
> + kvm_gmem_mnt = NULL;
> }
>
> static int kvm_gmem_migrate_folio(struct address_space *mapping,
> @@ -463,11 +503,72 @@ bool __weak kvm_arch_supports_gmem_mmap(struct kvm *kvm)
> return true;
> }
>
> +static struct inode *kvm_gmem_inode_make_secure_inode(const char *name,
> + loff_t size, u64 flags)
> +{
> + struct inode *inode;
> +
> + inode = anon_inode_make_secure_inode(kvm_gmem_mnt->mnt_sb, name, NULL);
> + if (IS_ERR(inode))
> + return inode;
> +
> + inode->i_private = (void *)(unsigned long)flags;
> + inode->i_op = &kvm_gmem_iops;
> + inode->i_mapping->a_ops = &kvm_gmem_aops;
> + inode->i_mode |= S_IFREG;
> + inode->i_size = size;
> + mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER);
> + mapping_set_inaccessible(inode->i_mapping);
> + /* Unmovable mappings are supposed to be marked unevictable as well. */
> + WARN_ON_ONCE(!mapping_unevictable(inode->i_mapping));
> +
> + return inode;
> +}
> +
> +static struct file *kvm_gmem_inode_create_getfile(void *priv, loff_t size,
> + u64 flags)
> +{
> + static const char *name = "[kvm-gmem]";
> + struct inode *inode;
> + struct file *file;
> + int err;
> +
> + err = -ENOENT;
> + /* __fput() will take care of fops_put(). */
> + if (!fops_get(&kvm_gmem_fops))
> + goto err;
> +
> + inode = kvm_gmem_inode_make_secure_inode(name, size, flags);
> + if (IS_ERR(inode)) {
> + err = PTR_ERR(inode);
> + goto err_fops_put;
> + }
> +
> + file = alloc_file_pseudo(inode, kvm_gmem_mnt, name, O_RDWR,
> + &kvm_gmem_fops);
> + if (IS_ERR(file)) {
> + err = PTR_ERR(file);
> + goto err_put_inode;
> + }
> +
> + file->f_flags |= O_LARGEFILE;
> + file->private_data = priv;
> +
> +out:
> + return file;
> +
> +err_put_inode:
> + iput(inode);
> +err_fops_put:
> + fops_put(&kvm_gmem_fops);
Thanks Ackerley.
LGTM
^ permalink raw reply
* Re: [PATCH RFC V10 5/7] KVM: guest_memfd: Add slab-allocated inode cache
From: Garg, Shivank @ 2025-08-13 6:10 UTC (permalink / raw)
To: seanjc, david, vbabka, willy, akpm, shuah, pbonzini, brauner,
viro
Cc: ackerleytng, paul, jmorris, serge, pvorel, bfoster, tabba,
vannapurve, chao.gao, bharata, nikunj, michael.day, shdhiman,
yan.y.zhao, Neeraj.Upadhyay, thomas.lendacky, michael.roth, aik,
jgg, kalyazin, peterx, jack, rppt, hch, cgzones, ira.weiny,
rientjes, roypat, ziy, matthew.brost, joshua.hahnjy, rakie.kim,
byungchul, gourry, kent.overstreet, ying.huang, apopple,
chao.p.peng, amit, ddutile, dan.j.williams, ashish.kalra, gshan,
jgowans, pankaj.gupta, papaluri, yuzhao, suzuki.poulose,
quic_eberman, aneeshkumar.kizhakeveetil, linux-fsdevel, linux-mm,
linux-kernel, linux-security-module, kvm, linux-kselftest,
linux-coco
In-Reply-To: <20250811090605.16057-11-shivankg@amd.com>
On 8/11/2025 2:36 PM, Shivank Garg wrote:
> Add dedicated inode structure (kvm_gmem_inode_info) and slab-allocated
> inode cache for guest memory backing, similar to how shmem handles inodes.
>
> This adds the necessary allocation/destruction functions and prepares
> for upcoming guest_memfd NUMA policy support changes.
>
> Signed-off-by: Shivank Garg <shivankg@amd.com>
> ---
> virt/kvm/guest_memfd.c | 69 ++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 67 insertions(+), 2 deletions(-)
>
> diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
> index 0e93323fc839..d9c23401e770 100644
> --- a/virt/kvm/guest_memfd.c
> +++ b/virt/kvm/guest_memfd.c
> @@ -17,6 +17,15 @@ struct kvm_gmem {
> struct list_head entry;
> };
>
> +struct kvm_gmem_inode_info {
> + struct inode vfs_inode;
> +};
> +
> +static inline struct kvm_gmem_inode_info *KVM_GMEM_I(struct inode *inode)
> +{
> + return container_of(inode, struct kvm_gmem_inode_info, vfs_inode);
> +}
> +
> /**
> * folio_file_pfn - like folio_file_page, but return a pfn.
> * @folio: The folio which contains this index.
> @@ -389,13 +398,46 @@ static struct file_operations kvm_gmem_fops = {
> .fallocate = kvm_gmem_fallocate,
> };
>
> +static struct kmem_cache *kvm_gmem_inode_cachep;
> +
> +static struct inode *kvm_gmem_alloc_inode(struct super_block *sb)
> +{
> + struct kvm_gmem_inode_info *info;
> +
> + info = alloc_inode_sb(sb, kvm_gmem_inode_cachep, GFP_KERNEL);
> + if (!info)
> + return NULL;
> +
> + return &info->vfs_inode;
> +}
> +
> +static void kvm_gmem_destroy_inode(struct inode *inode)
> +{
> +}
> +
> +static void kvm_gmem_free_inode(struct inode *inode)
> +{
> + kmem_cache_free(kvm_gmem_inode_cachep, KVM_GMEM_I(inode));
> +}
> +
> +static const struct super_operations kvm_gmem_super_operations = {
> + .statfs = simple_statfs,
> + .alloc_inode = kvm_gmem_alloc_inode,
> + .destroy_inode = kvm_gmem_destroy_inode,
> + .free_inode = kvm_gmem_free_inode,
> +};
> +
> static int kvm_gmem_init_fs_context(struct fs_context *fc)
> {
> + struct pseudo_fs_context *ctx;
> +
> if (!init_pseudo(fc, GUEST_MEMFD_MAGIC))
> return -ENOMEM;
>
> fc->s_iflags |= SB_I_NOEXEC;
> fc->s_iflags |= SB_I_NODEV;
> + ctx = fc->fs_private;
> + ctx->ops = &kvm_gmem_super_operations;
>
> return 0;
> }
> @@ -417,17 +459,40 @@ static int kvm_gmem_init_mount(void)
> return 0;
> }
>
> +static void kvm_gmem_init_inode(void *foo)
> +{
> + struct kvm_gmem_inode_info *info = foo;
> +
> + inode_init_once(&info->vfs_inode);
> +}
> +
> int kvm_gmem_init(struct module *module)
> {
> - kvm_gmem_fops.owner = module;
> + int ret;
> + struct kmem_cache_args args = {
> + .align = 0,
> + .ctor = kvm_gmem_init_inode,
> + };
>
> - return kvm_gmem_init_mount();
> + kvm_gmem_fops.owner = module;
> + kvm_gmem_inode_cachep = kmem_cache_create("kvm_gmem_inode_cache",
> + sizeof(struct kvm_gmem_inode_info),
> + &args, SLAB_ACCOUNT);
> + if (!kvm_gmem_inode_cachep)
> + return -ENOMEM;
> + ret = kvm_gmem_init_mount();
> + if (ret) {
> + kmem_cache_destroy(kvm_gmem_inode_cachep);
> + return ret;
> + }
> + return 0;
> }
>
> void kvm_gmem_exit(void)
> {
> kern_unmount(kvm_gmem_mnt);
> kvm_gmem_mnt = NULL;
> + kmem_cache_destroy(kvm_gmem_inode_cachep);
> }
While testing my code, I discovered a bug that occurs when unloading the kvm_amd module
after a guest_memfd-backed VM has run.
dmesg logs:
[ 610.075763] =============================================================================
[ 610.083933] BUG kvm_gmem_inode_cache (Not tainted): Objects remaining on __kmem_cache_shutdown()
[ 610.092711] -----------------------------------------------------------------------------
[ 610.102368] Object 0x000000008ee52a58 @offset=19200
[ 610.107247] Slab 0x000000004b1b088c objects=51 used=1 fp=0x000000007c55fc00 flags=0x57ffffc0000240(workingset|head|node=1|zone=2|lastcpupid=0x1fffff)
[ 610.120733] Disabling lock debugging due to kernel taint
[ 610.120741] ------------[ cut here ]------------
[ 610.120742] WARNING: CPU: 7 PID: 7554 at mm/slub.c:1171 __kmem_cache_shutdown+0x264/0x370
[ 610.120751] Modules linked in: xt_set ip_set xt_addrtype xfrm_user xfrm_algo xt_CHECKSUM xt_MASQUERADE xt_conntrack ipt_REJECT nf_reject_ipv4 nft_compat nff_defrag_ipv4 nf_tables overlay bridge stp llc cfg80211 rfkill binfmt_misc ipmi_ssif amd_atl intel_rapl_msr wmi_bmof intel_rapl_common amd64_edac edac_mce_amdmem_helper drm_kms_helper i2c_piix4 ptdma i2c_smbus k10temp wmi acpi_power_meter ipmi_si acpi_ipmi ipmi_devintf ipmi_msghandler sg dm_multipath fuse drm dm_mo56 async_raid6_recov async_memcpy async_pq async_xor xor async_tx raid6_pq raid1 raid0 sd_mod kvm_amd(-) ahci libahci kvm nvme tg3 libata ccp irqbypass nvme_c
[ 610.120831] CPU: 7 UID: 0 PID: 7554 Comm: rmmod Kdump: loaded Tainted: G B 6.16.0+ #10 PREEMPT(none)
[ 610.120835] Tainted: [B]=BAD_PAGE
[ 610.120836] Hardware name: Dell Inc. PowerEdge R6525/024PW1, BIOS 2.16.2 07/09/2024
[ 610.120838] RIP: 0010:__kmem_cache_shutdown+0x264/0x370
[ 610.120841] Code: 89 f1 4c 89 f6 4d 8b 46 20 48 c7 c7 08 08 ec 87 81 e2 ff 7f 00 00 e8 fb a7 d7 ff be 01 00 00 00 bf 05 00 00 00 e8 dc e9 cd ff <0f> 0b 48 fe ff ff
[ 610.120843] RSP: 0018:ffffcd6962963cb8 EFLAGS: 00010046
[ 610.120846] RAX: 0000000000000000 RBX: ffff89fde07d21c0 RCX: 0000000000000027
[ 610.120848] RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff89fcbe5dbe80
[ 610.120850] RBP: ffff89fde07d21c0 R08: 0000000000000000 R09: 0000000000000003
[ 610.120851] R10: ffffcd6962963b58 R11: ffffffff889db908 R12: ffff89fdcccd7f80
[ 610.120852] R13: ffff89fdcccd0000 R14: fffff96802333400 R15: ffff89fdd6ab6c00
[ 610.120854] FS: 00007f066eaab080(0000) GS:ffff89fd3516f000(0000) knlGS:0000000000000000
[ 610.120856] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 610.120857] CR2: 00007ffefd577828 CR3: 0000000220406004 CR4: 0000000000770ef0
[ 610.120859] PKRU: 55555554
[ 610.120860] Call Trace:
[ 610.120862] <TASK>
[ 610.120866] kmem_cache_destroy+0x3a/0x150
[ 610.120872] kvm_exit+0x7b/0xa0 [kvm]
[ 610.120919] svm_exit+0x5/0x10 [kvm_amd]
[ 610.120926] __do_sys_delete_module.isra.0+0x18b/0x2e0
[ 610.120933] ? srso_alias_return_thunk+0x5/0xfbef5
[ 610.120937] ? syscall_trace_enter+0xfa/0x1a0
[ 610.120941] do_syscall_64+0x7b/0x2c0
[ 610.120947] ? srso_alias_return_thunk+0x5/0xfbef5
[ 610.120950] ? __handle_mm_fault+0x2aa/0x670
[ 610.120954] ? iterate_dir+0x11e/0x230
[ 610.120960] ? srso_alias_return_thunk+0x5/0xfbef5
[ 610.120963] ? count_memcg_events+0xb2/0x160
[ 610.120967] ? srso_alias_return_thunk+0x5/0xfbef5
[ 610.120969] ? handle_mm_fault+0xb2/0x2f0
[ 610.120972] ? srso_alias_return_thunk+0x5/0xfbef5
[ 610.120975] ? do_user_addr_fault+0x16f/0x6f0
[ 610.120981] ? srso_alias_return_thunk+0x5/0xfbef5
[ 610.120984] entry_SYSCALL_64_after_hwframe+0x76/0x7e
[ 610.120986] RIP: 0033:0x7f066e12ac9b
[ 610.120989] Code: 73 01 c3 48 8b 0d 7d 81 0d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 b0 00 00 00 0f 05 <48> 3d 01 89 01 48
[ 610.120990] RSP: 002b:00007ffc629f1878 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
[ 610.120993] RAX: ffffffffffffffda RBX: 00005630e80256f0 RCX: 00007f066e12ac9b
[ 610.120994] RDX: 0000000000000000 RSI: 0000000000000800 RDI: 00005630e8025758
[ 610.120996] RBP: 00007ffc629f18a0 R08: 1999999999999999 R09: 0000000000000000
[ 610.120997] R10: 00007f066e1b1fc0 R11: 0000000000000206 R12: 0000000000000000
[ 610.120999] R13: 00007ffc629f1af0 R14: 00005630e80256f0 R15: 0000000000000000
[ 610.121003] </TASK>
[ 610.121004] ---[ end trace 0000000000000000 ]---
[ 610.121017] ------------[ cut here ]------------
There is a race condition here:
kern_unmount() -> mntput() -> cleanup_mnt() -> deactivate_super() -> deactivate_locked_super() -> fs->kill_sb() (guest_memfd kill_sb) -> generic_shutdown_super() -> evict_inodes() -> destroy_inode() -> call_rcu()
I should be waiting for pending RCU callback to finish before calling the kmem_cache_destroy().
To fix this, I added rcu_barrier() like dax_fs_exit() is doing.
@@ -561,6 +566,7 @@ void kvm_gmem_exit(void)
{
kern_unmount(kvm_gmem_mnt);
kvm_gmem_mnt = NULL;
+ rcu_barrier();
kmem_cache_destroy(kvm_gmem_inode_cachep);
}
I'll incorporate this fix into next version.
Thanks,
Shivank
^ permalink raw reply
* Re: [RFC PATCH 1/6] fs/9p: Add ability to identify inode by path for .L
From: Mickaël Salaün @ 2025-08-13 7:47 UTC (permalink / raw)
To: Tingmao Wang
Cc: Dominique Martinet, Al Viro, Eric Van Hensbergen,
Latchesar Ionkov, Christian Schoenebeck, v9fs, Günther Noack,
linux-security-module, Jan Kara, Amir Goldstein,
Matthew Bobrowski, linux-fsdevel
In-Reply-To: <df6cb208-cb14-4ca5-bd25-cb0f05bfc6a1@maowtm.org>
On Wed, Aug 13, 2025 at 12:57:49AM +0100, Tingmao Wang wrote:
> Thanks for the review :) I will try to send a v2 in the coming weeks with
> the two changes you suggested and the changes to cached mode as suggested
> by Dominique (plus rename handling). (will also try to figure out how to
> test with xfstests)
>
> On 8/8/25 09:32, Mickaël Salaün wrote:
> > [...]
> >> On 7/5/25 01:25, Al Viro wrote:
> >>> On Sun, Apr 06, 2025 at 09:43:02PM +0100, Tingmao Wang wrote:
> >>>> +bool ino_path_compare(struct v9fs_ino_path *ino_path,
> >>>> + struct dentry *dentry)
> >>>> +{
> >>>> + struct dentry *curr = dentry;
> >>>> + struct qstr *curr_name;
> >>>> + struct name_snapshot *compare;
> >>>> + ssize_t i;
> >>>> +
> >>>> + lockdep_assert_held_read(&v9fs_dentry2v9ses(dentry)->rename_sem);
> >>>> +
> >>>> + rcu_read_lock();
> >>>> + for (i = ino_path->nr_components - 1; i >= 0; i--) {
> >>>> + if (curr->d_parent == curr) {
> >>>> + /* We're supposed to have more components to walk */
> >>>> + rcu_read_unlock();
> >>>> + return false;
> >>>> + }
> >>>> + curr_name = &curr->d_name;
> >>>> + compare = &ino_path->names[i];
> >>>> + /*
> >>>> + * We can't use hash_len because it is salted with the parent
> >>>> + * dentry pointer. We could make this faster by pre-computing our
> >>>> + * own hashlen for compare and ino_path outside, probably.
> >>>> + */
> >>>> + if (curr_name->len != compare->name.len) {
> >>>> + rcu_read_unlock();
> >>>> + return false;
> >>>> + }
> >>>> + if (strncmp(curr_name->name, compare->name.name,
> >>>> + curr_name->len) != 0) {
> >>>
> >>> ... without any kind of protection for curr_name. Incidentally,
> >>> what about rename()? Not a cross-directory one, just one that
> >>> changes the name of a subdirectory within the same parent?
> >>
> >> As far as I can tell, in v9fs_vfs_rename, v9ses->rename_sem is taken for
> >> both same-parent and different parent renames, so I think we're safe here
> >> (and hopefully for any v9fs dentries, nobody should be causing d_name to
> >> change except for ourselves when we call d_move in v9fs_vfs_rename? If
> >> yes then because we also take v9ses->rename_sem, in theory we should be
> >> fine here...?)
> >
> > A lockdep_assert_held() or similar and a comment would make this clear.
>
> I can add a comment, but there is already a lockdep_assert_held_read of
> the v9fs rename sem at the top of this function.
I wrote this comment before reading your new version beneath, which
already have this lockdep, so no need to change anything. :)
>
> > [...]
> >> /*
> >> * Must hold rename_sem due to traversing parents
> >> */
> >> bool ino_path_compare(struct v9fs_ino_path *ino_path, struct dentry *dentry)
> >> {
> >> struct dentry *curr = dentry;
> >> struct name_snapshot *compare;
> >> ssize_t i;
> >>
> >> lockdep_assert_held_read(&v9fs_dentry2v9ses(dentry)->rename_sem);
> >>
> >> rcu_read_lock();
> >> for (i = ino_path->nr_components - 1; i >= 0; i--) {
> >> if (curr->d_parent == curr) {
> >> /* We're supposed to have more components to walk */
> >> rcu_read_unlock();
> >> return false;
> >> }
> >> compare = &ino_path->names[i];
> >> if (!d_same_name(curr, curr->d_parent, &compare->name)) {
> >> rcu_read_unlock();
> >> return false;
> >> }
> >> curr = curr->d_parent;
> >> }
> >> rcu_read_unlock();
> >> if (curr != curr->d_parent) {
>
> Looking at this again I think this check probably needs to be done inside
> RCU, will fix as below:
>
> >> /* dentry is deeper than ino_path */
> >> return false;
> >> }
> >> return true;
> >> }
>
> diff --git a/fs/9p/ino_path.c b/fs/9p/ino_path.c
> index 0000b4964df0..7264003cb087 100644
> --- a/fs/9p/ino_path.c
> +++ b/fs/9p/ino_path.c
> @@ -77,13 +77,15 @@ void free_ino_path(struct v9fs_ino_path *path)
> }
>
> /*
> - * Must hold rename_sem due to traversing parents
> + * Must hold rename_sem due to traversing parents. Returns whether
> + * ino_path matches with the path of a v9fs dentry.
> */
> bool ino_path_compare(struct v9fs_ino_path *ino_path, struct dentry *dentry)
> {
> struct dentry *curr = dentry;
> struct name_snapshot *compare;
> ssize_t i;
> + bool ret;
>
> lockdep_assert_held_read(&v9fs_dentry2v9ses(dentry)->rename_sem);
>
> @@ -101,10 +103,8 @@ bool ino_path_compare(struct v9fs_ino_path *ino_path, struct dentry *dentry)
> }
> curr = curr->d_parent;
> }
> + /* Comparison fails if dentry is deeper than ino_path */
> + ret = (curr == curr->d_parent);
> rcu_read_unlock();
> - if (curr != curr->d_parent) {
> - /* dentry is deeper than ino_path */
> - return false;
> - }
> - return true;
> + return ret;
> }
Looks good
>
> >
> > I like this new version.
> >
>
^ permalink raw reply
* Re: [PATCH] x86/bpf: use bpf_capable() instead of capable(CAP_SYS_ADMIN)
From: Ondrej Mosnacek @ 2025-08-13 9:49 UTC (permalink / raw)
To: Alexei Starovoitov
Cc: Serge E. Hallyn, daniel.sneddon, Pawan Gupta, Dave Hansen,
alexandre.chartre, Alexei Starovoitov, Daniel Borkmann, bpf,
selinux, LSM List
In-Reply-To: <CAADnVQKY0z1RAJdAmRGbLWZxrJPG6Kawe6_qQHjoVM7Xz8CfuA@mail.gmail.com>
On Sat, Aug 9, 2025 at 2:46 AM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> On Fri, Aug 8, 2025 at 4:59 PM Serge E. Hallyn <serge@hallyn.com> wrote:
> >
> > On Wed, Aug 06, 2025 at 08:18:55PM -0500, Serge E. Hallyn wrote:
> > > On Wed, Aug 06, 2025 at 04:31:05PM +0200, Ondrej Mosnacek wrote:
> > > > Don't check against the overloaded CAP_SYS_ADMINin do_jit(), but instead
> > > > use bpf_capable(), which checks against the more granular CAP_BPF first.
> > > > Going straight to CAP_SYS_ADMIN may cause unnecessary audit log spam
> > > > under SELinux, as privileged domains using BPF would usually only be
> > > > allowed CAP_BPF and not CAP_SYS_ADMIN.
> > > >
> > > > Link: https://bugzilla.redhat.com/show_bug.cgi?id=2369326
> > > > Fixes: d4e89d212d40 ("x86/bpf: Call branch history clearing sequence on exit")
> > > > Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
> > >
> > > So this seems correct, *provided* that we consider it within the purview of
> > > CAP_BPF to be able to avoid clearing the branch history buffer.
>
> true, but...
>
> > >
> > > I suspect that's the case, but it might warrant discussion.
> > >
> > > Reviewed-by: Serge Hallyn <serge@hallyn.com>
> >
> > (BTW, I'm assuming this will get pulled into a BPF tree or something, and
> > doesn't need to go into the capabilities tree. Let me know if that's wrong)
>
> Right.
> scripts/get_maintainer.pl arch/x86/net/bpf_jit_comp.c
> is your friend.
>
> Pls cc author-s of the commit in question in the future.
> Adding them now.
>
> > > > diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
> > > > index 15672cb926fc1..2a825e5745ca1 100644
> > > > --- a/arch/x86/net/bpf_jit_comp.c
> > > > +++ b/arch/x86/net/bpf_jit_comp.c
> > > > @@ -2591,8 +2591,7 @@ emit_jmp:
> > > > seen_exit = true;
> > > > /* Update cleanup_addr */
> > > > ctx->cleanup_addr = proglen;
> > > > - if (bpf_prog_was_classic(bpf_prog) &&
> > > > - !capable(CAP_SYS_ADMIN)) {
> > > > + if (bpf_prog_was_classic(bpf_prog) && !bpf_capable()) {
>
> This looks wrong for several reasons.
>
> 1.
> bpf_capable() and CAP_BPF in general applies to eBPF only.
> There is no precedent so far to do anything differently
> for cBPF when CAP_BPF is present.
That's not entirely true, see below.
> 2.
> commit log states that
> "privileged domains using BPF would usually only be allowed CAP_BPF
> and not CAP_SYS_ADMIN"
> which is true for eBPF only, since cBPF is always allowed for
> all unpriv users.
> Start chrome browser and you get cBPF loaded.
Processes using cBPF (via SO_ATTACH_FILTER) already can trigger a
CAP_BPF check - when the net.core.bpf_jit_harden sysctl is set to 1,
then the sequence sk_attach_filter() -> __get_filter() ->
bpf_prog_alloc() -> bpf_prog_alloc_no_stats() ->
bpf_jit_blinding_enabled() -> bpf_token_capable() happens for the same
iio-sensor-proxy syscall as the one that hits the CAP_SYS_ADMIN check.
Because of this we have already granted the BPF capability in
Fedora/RHEL SELinux policy to many domains that would usually run as
root and that use SO_ATTACH_FILTER. The logic being that they are
legitimately using BPF + without SELinux they would be fully
privileged (root) and they would pass that check + it seemed they
could otherwise lose some performance due to the hardening (though I'm
not sure now if it applies to cBPF, so this point could be moot) +
CAP_BPF doesn't grant any excess privileges beyond this (as opposed to
e.g. CAP_SYS_ADMIN). This is what I meant behind that commit log
statement, though I didn't remember the details, so I didn't state it
as clearly as I could have (my apologies).
Now this same usage started triggering the new plain CAP_SYS_ADMIN
check so I naturally assumed that changing it to bpf_capable() would
be the most logical solution (as it would let us keep the services
excluded from the hardening via CAP_BPF without granting the broad
CAP_SYS_ADMIN).
Is the fact that CAP_BPF check is reachable via cBPF use unexpected
behavior? If both cBPF and eBPF can be JIT'd and CAP_BPF is already
being used for the "exempt from JIT hardening" semantics in one place,
why should cBPF and eBPF be treated differently? In fact, shouldn't
the decision to apply the Spectre mitigation also take into account
the net.core.bpf_jit_harden sysctl even when the program is not cBPF?
> 3.
> glancing over bugzilla it seems that the issue is
> excessive audit spam and not related to CAP_BPF and privileges.
> If so then the fix is to use
> ns_capable_noaudit(&init_user_ns, CAP_SYS_ADMIN)
>
> 4.
> I don't understand how the patch is supposed to fix the issue.
> iio-sensor-proxy is probably unpriv. Why would it use CAP_BPF?
> It's using cBPF, so there is no reason for it to have CAP_BPF.
> So capable(CAP_BPF) will fail just like capable(CAP_SYS_ADMIN),
> but since CAP_BPF check was done first, the audit won't
> be printed, because it's some undocumented internal selinux behavior ?
> None of it is in the commit log :(
It is not unprivileged. It runs as root and without SELinux it would
have all capabilities allowed. If it were running without any
capabilities, then indeed there would be no SELinux checks.
> 5.
> And finally all that looks like a selinux bug.
> Just because something in the kernel is asking capable(CAP_SYS_ADMIN)
> there is no need to spam users with the wrong message:
> "SELinux is preventing iio-sensor-prox from using the 'sys_admin' capabilities."
> iio-sensor-prox is not trying to use 'sys_admin' capabilities.
> cBPF prog will be loaded anyway, with or without BHB clearing.
Well, it depends... In this case the AVC denial informs us that the
kernel is making some decision depending on the capability and that a
decision should be made in the policy to allow or silence the access
vector. Even when the consequence is not a failure of the syscall, it
still may be useful to have the denial reported, since there is a
potential performance impact. OTOH, with CAP_SYS_ADMIN if the decision
is to not allow it, then silencing it via a dontaudit rule would
potentially hide other more critical CAP_SYS_ADMIN denials, so it's
hard to decide what is better - to silence this specific case in the
kernel vs. to let the user allow/silence the specific AV in the
policy...
--
Ondrej Mosnacek
Senior Software Engineer, Linux Security - SELinux kernel
Red Hat, Inc.
^ permalink raw reply
* [PATCH] apparmor: Remove unused value
From: Chandra Mohan Sundar @ 2025-08-13 16:01 UTC (permalink / raw)
To: john.johansen, paul, jmorris, serge, apparmor,
linux-security-module, linux-kernel, shuah
Cc: Chandra Mohan Sundar, linux-kernel-mentees
The value "new" is being assigned to NULL but that statement does not
have effect since "new" is being overwritten in the subsequent fallback case.
Remove the unused value. This issue was reported by coverity static
analyzer.
Fixes: a9eb185be84e9 (apparmor: fix x_table_lookup)
Signed-off-by: Chandra Mohan Sundar <chandramohan.explore@gmail.com>
---
security/apparmor/domain.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c
index 267da82afb14..9c0c7fa8de46 100644
--- a/security/apparmor/domain.c
+++ b/security/apparmor/domain.c
@@ -592,7 +592,6 @@ static struct aa_label *x_to_label(struct aa_profile *profile,
if (!new || **lookupname != '&')
break;
stack = new;
- new = NULL;
fallthrough; /* to X_NAME */
case AA_X_NAME:
if (xindex & AA_X_CHILD)
--
2.43.0
^ permalink raw reply related
* [PATCH v3 00/12] Signed BPF programs
From: KP Singh @ 2025-08-13 20:55 UTC (permalink / raw)
To: bpf, linux-security-module; +Cc: bboscaccy, paul, kys, ast, daniel, andrii
# v2 -> v3
* Dropped unstable test where function can be inlined and only select few
LSKEL tests are using signing per Alexei's request
* Some other feedback incorporated.
#v1 -> v2
* Addressed feedback on excl maps and their implementation
* fixed s390x and other tests that were failing in the CI.
* using the kernel's sha256 API since it now uses acceleration if available
* simple signing test case, this can be extended to inject a false SHA into
the loader
BPF Signing has gone over multiple discussions in various conferences with the
kernel and BPF community and the following patch series is a culmination
of the current of discussion and signed BPF programs. Once signing is
implemented, the next focus would be to implement the right security policies
for all BPF use-cases (dynamically generated bpf programs, simple non CO-RE
programs).
Signing also paves the way for allowing unrivileged users to
load vetted BPF programs and helps in adhering to the principle of least
privlege by avoiding unnecessary elevation of privileges to CAP_BPF and
CAP_SYS_ADMIN (ofcourse, with the appropriate security policy active).
A early version of this design was proposed in [1]:
# General Idea: Trusted Hash Chain
The key idea of the design is to use a signing algorithm that allows
us to integrity-protect a number of future payloads, including their
order, by creating a chain of trust.
Consider that Alice needs to send messages M_1, M_2, ..., M_n to Bob.
We define blocks of data such that:
B_n = M_n || H(termination_marker)
(Each block contains its corresponding message and the hash of the
*next* block in the chain.)
B_{n-1} = M_{n-1} || H(B_n)
B_{n-2} = M_{n-2} || H(B_{n-1})
...
B_2 = M_2 || H(B_3)
B_1 = M_1 || H(B_2)
Alice does the following (e.g., on a build system where all payloads
are available):
* Assembles the blocks B_1, B_2, ..., B_n.
* Calculates H(B_1) and signs it, yielding Sig(H(B_1)).
Alice sends the following to Bob:
M_1, H(B_2), Sig(H(B_1))
Bob receives this payload and does the following:
* Reconstructs B_1 as B_1' using the received M_1 and H(B_2)
(i.e., B_1' = M_1 || H(B_2)).
* Recomputes H(B_1') and verifies the signature against the
received Sig(H(B_1)).
* If the signature verifies, it establishes the integrity of M_1
and H(B_2) (and transitively, the integrity of the entire chain). Bob
now stores the verified H(B_2) until it receives the next message.
* When Bob receives M_2 (and H(B_3) if n > 2), it reconstructs
B_2' (e.g., B_2' = M_2 || H(B_3), or if n=2, B_2' = M_2 ||
H(termination_marker)). Bob then computes H(B_2') and compares it
against the stored H(B_2) that was verified in the previous step.
This process continues until the last block is received and verified.
Now, applying this to the BPF signing use-case, we simplify to two messages:
M_1 = I_loader (the instructions of the loader program)
M_2 = M_metadata (the metadata for the loader program, passed in a
map, which includes the programs to be loaded and other context)
For this specific BPF case, we will directly sign a composite of the
first message and the hash of the second. Let H_meta = H(M_metadata).
The block to be signed is effectively:
B_signed = I_loader || H_meta
The signature generated is Sig(B_signed).
The process then follows a similar pattern to the Alice and Bob model,
where the kernel (Bob) verifies I_loader and H_meta using the
signature. Then, the trusted I_loader is responsible for verifying
M_metadata against the trusted H_meta.
From an implementation standpoint:
# Build
bpftool (or some other tool in a trusted build environment) knows
about the metadata (M_metadata) and the loader program (I_loader). It
first calculates H_meta = H(M_metadata). Then it constructs the object
to be signed and computes the signature:
Sig(I_loader || H_meta)
# Loader
The loader program and the metadata are a hermetic representation of the source
of the eBPF program, its maps and context. The loader program is generated by
libbpf as a part of a standard API i.e. bpf_object__gen_loader.
## Supply chain
While users can use light skeletons as a convenient method to use signing
support, they can directly use the loader program generation using libbpf
(bpf_object__gen_loader) into their own trusted toolchains.
libbpf, which has access to the program's instruction buffer is a key part of
the TCB of the build environment
An advanced threat model that does not intend to depend on libbpf (or any provenant
userspace BPF libraries) due to supply chain risks despite it being developed
in the kernel source and by the kernel community will require reimplmenting a
lot of the core BPF userspace support (like instruction relocation, map handling).
Such an advanced user would also need to integrate the generation of the loader
into their toolchain.
Given that many use-cases (e.g. Cilium) generate trusted BPF programs,
trusted loaders are an inevitability and a requirement for signing support, a
entrusting loader programs will be a fundamental requirement for an security
policy.
The initial instructions of the loader program verify the SHA256 hash
of the metadata (M_metadata) that will be passed in a map. These instructions
effectively embed the precomputed H_meta as immediate values.
ld_imm64 r1, const_ptr_to_map // insn[0].src_reg == BPF_PSEUDO_MAP_IDX
r2 = *(u64 *)(r1 + 0);
ld_imm64 r3, sha256_of_map_part1 // precomputed by bpf_object__gen_load/libbpf (H_meta_1)
if r2 != r3 goto out;
r2 = *(u64 *)(r1 + 8);
ld_imm64 r3, sha256_of_map_part2 // precomputed by bpf_object__gen_load/libbpf (H_meta_2)
if r2 != r3 goto out;
r2 = *(u64 *)(r1 + 16);
ld_imm64 r3, sha256_of_map_part3 // precomputed by bpf_object__gen_load/libbpf (H_meta_3)
if r2 != r3 goto out;
r2 = *(u64 *)(r1 + 24);
ld_imm64 r3, sha256_of_map_part4 // precomputed by bpf_object__gen_load/libbpf (H_meta_4)
if r2 != r3 goto out;
...
This implicitly makes the payload equivalent to the signed block (B_signed)
I_loader || H_meta
bpftool then generates the signature of this I_loader payload (which
now contains the expected H_meta) using a key and an identity:
This signature is stored in bpf_attr, which is extended as follows for
the BPF_PROG_LOAD command:
__aligned_u64 signature;
__u32 signature_size;
__u32 keyring_id;
The reasons for a simpler UAPI is that it's more future proof (e.g.) with more
stable instruction buffers, loader programs being directly into the compilers.
A simple API also allows simple programs e.g. for networking that don't need
loader programs to directly use signing.
# Extending OBJ_GET_INFO_BY_FD for hashes
OBJ_GET_INFO_BY_FD is used to get information about BPF objects (maps, programs, links) and
returning the hash of the map is a natural extension of the UAPI as it can be
helpful for debugging, fingerprinting etc.
Currently, it's only implemented for BPF_MAP_TYPE_ARRAY. It can be trivially
extended for BPF programs to return the complete SHA256 along with the tag.
The SHA is stored in struct bpf_map for exclusive and frozen maps
struct bpf_map {
+ u64 sha[4];
const struct bpf_map_ops *ops;
struct bpf_map *inner_map_meta;
};
## Exclusive BPF maps
Exclusivity ensures that the map can only be used by a future BPF
program whose SHA256 hash matches sha256_of_future_prog.
First, bpf_prog_calc_tag() is updated to compute the SHA256 instead of
SHA1, and this hash is stored in struct bpf_prog_aux:
@@ -1588,6 +1588,7 @@ struct bpf_prog_aux {
int cgroup_atype; /* enum cgroup_bpf_attach_type */
struct bpf_map *cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE];
char name[BPF_OBJ_NAME_LEN];
+ u64 sha[4];
u64 (*bpf_exception_cb)(u64 cookie, u64 sp, u64 bp, u64, u64);
// ...
};
An exclusive is created by passing an excl_prog_hash
(and excl_prog_hash_size) in the BPF_MAP_CREATE command.
When a BPF program is subsequently loaded and it attempts to use this map,
the kernel will compare the program's own SHA256 hash against the one
registered with the map, if matching, it will be added to prog->used_maps[].
The program load will fail if the hashes do not match or if the map is
already in use by another (non-matching) exclusive program.
Exclusive maps ensure that no other BPF programs and compromise the intergity of
the map post the signature verification.
NOTE: Exclusive maps cannot be added as inner maps.
# Light Skeleton Sequence (Userspace Example)
err = map_fd = skel_map_create(BPF_MAP_TYPE_ARRAY, "__loader.map",
opts->excl_prog_hash,
opts->excl_prog_hash_sz, 4,
opts->data_sz, 1);
err = skel_map_update_elem(map_fd, &key, opts->data, 0);
err = skel_map_freeze(map_fd);
// Kernel computes the hash of the map.
err = skel_obj_get_info_by_fd(map_fd);
memset(&attr, 0, prog_load_attr_sz);
attr.prog_type = BPF_PROG_TYPE_SYSCALL;
attr.insns = (long) opts->insns;
attr.insn_cnt = opts->insns_sz / sizeof(struct bpf_insn);
attr.signature = (long) opts->signature;
attr.signature_size = opts->signature_sz;
attr.keyring_id = opts->keyring_id;
attr.license = (long) "Dual BSD/GPL";
The kernel will:
* Compute the hash of the provided I_loader bytecode.
* Verify the signature against this computed hash.
* Check if the metadata map (now exclusive) is intended for this
program's hash.
The signature check happens in BPF_PROG_LOAD before the security_bpf_prog
LSM hook.
This ensures that the loaded loader program (I_loader), including the
embedded expected hash of the metadata (H_meta), is trusted.
Since the loader program is now trusted, it can be entrusted to verify
the actual metadata (M_metadata) read from the (now exclusive and
frozen) map against the embedded (and trusted) H_meta. There is no
Time-of-Check-Time-of-Use (TOCTOU) vulnerability here because:
* The signature covers the I_loader and its embedded H_meta.
* The metadata map M_metadata is frozen before the loader program is loaded
and associated with it.
* The map is made exclusive to the specific (signed and verified)
loader program.
[1] https://lore.kernel.org/bpf/CACYkzJ6VQUExfyt0=-FmXz46GHJh3d=FXh5j4KfexcEFbHV-vg@mail.gmail.com/#t
KP Singh (12):
bpf: Update the bpf_prog_calc_tag to use SHA256
bpf: Implement exclusive map creation
libbpf: Implement SHA256 internal helper
libbpf: Support exclusive map creation
selftests/bpf: Add tests for exclusive maps
bpf: Return hashes of maps in BPF_OBJ_GET_INFO_BY_FD
bpf: Move the signature kfuncs to helpers.c
bpf: Implement signature verification for BPF programs
libbpf: Update light skeleton for signing
libbpf: Embed and verify the metadata hash in the loader
bpftool: Add support for signing BPF programs
selftests/bpf: Enable signature verification for some lskel tests
crypto/asymmetric_keys/pkcs7_verify.c | 1 +
include/linux/bpf.h | 42 +++-
include/linux/filter.h | 6 -
include/linux/verification.h | 1 +
include/uapi/linux/bpf.h | 14 ++
kernel/bpf/Kconfig | 2 +-
kernel/bpf/arraymap.c | 13 ++
kernel/bpf/core.c | 50 +----
kernel/bpf/helpers.c | 166 ++++++++++++++
kernel/bpf/syscall.c | 97 +++++++-
kernel/bpf/verifier.c | 6 +
kernel/trace/bpf_trace.c | 183 ---------------
.../bpf/bpftool/Documentation/bpftool-gen.rst | 16 +-
.../bpftool/Documentation/bpftool-prog.rst | 18 +-
tools/bpf/bpftool/Makefile | 6 +-
tools/bpf/bpftool/cgroup.c | 4 +
tools/bpf/bpftool/gen.c | 60 ++++-
tools/bpf/bpftool/main.c | 26 ++-
tools/bpf/bpftool/main.h | 11 +
tools/bpf/bpftool/prog.c | 27 ++-
tools/bpf/bpftool/sign.c | 212 ++++++++++++++++++
tools/include/uapi/linux/bpf.h | 14 ++
tools/lib/bpf/bpf.c | 6 +-
tools/lib/bpf/bpf.h | 4 +-
tools/lib/bpf/bpf_gen_internal.h | 2 +
tools/lib/bpf/gen_loader.c | 55 +++++
tools/lib/bpf/libbpf.c | 125 +++++++++++
tools/lib/bpf/libbpf.h | 21 +-
tools/lib/bpf/libbpf.map | 2 +
tools/lib/bpf/libbpf_internal.h | 4 +
tools/lib/bpf/skel_internal.h | 75 ++++++-
tools/testing/selftests/bpf/.gitignore | 1 +
tools/testing/selftests/bpf/Makefile | 35 ++-
.../selftests/bpf/prog_tests/map_excl.c | 56 +++++
tools/testing/selftests/bpf/progs/map_excl.c | 34 +++
.../selftests/bpf/progs/verifier_map_ptr.c | 7 +-
tools/testing/selftests/bpf/test_progs.c | 13 ++
.../testing/selftests/bpf/verify_sig_setup.sh | 13 +-
38 files changed, 1161 insertions(+), 267 deletions(-)
create mode 100644 tools/bpf/bpftool/sign.c
create mode 100644 tools/testing/selftests/bpf/prog_tests/map_excl.c
create mode 100644 tools/testing/selftests/bpf/progs/map_excl.c
--
2.43.0
^ permalink raw reply
* [PATCH v3 01/12] bpf: Update the bpf_prog_calc_tag to use SHA256
From: KP Singh @ 2025-08-13 20:55 UTC (permalink / raw)
To: bpf, linux-security-module
Cc: bboscaccy, paul, kys, ast, daniel, andrii, KP Singh
In-Reply-To: <20250813205526.2992911-1-kpsingh@kernel.org>
Exclusive maps restrict map access to specific programs using a hash.
The current hash used for this is SHA1, which is prone to collisions.
This patch uses SHA256, which is more resilient against
collisions. This new hash is stored in bpf_prog and used by the verifier
to determine if a program can access a given exclusive map.
The original 64-bit tags are kept, as they are used by users as a short,
possibly colliding program identifier for non-security purposes.
Signed-off-by: KP Singh <kpsingh@kernel.org>
---
include/linux/bpf.h | 6 ++++-
include/linux/filter.h | 6 -----
kernel/bpf/Kconfig | 2 +-
kernel/bpf/core.c | 50 +++++++-----------------------------------
4 files changed, 14 insertions(+), 50 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index e7ee089e8a31..b98c5b5bf2a1 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -31,6 +31,7 @@
#include <linux/memcontrol.h>
#include <linux/cfi.h>
#include <asm/rqspinlock.h>
+#include <crypto/sha2.h>
struct bpf_verifier_env;
struct bpf_verifier_log;
@@ -1711,7 +1712,10 @@ struct bpf_prog {
enum bpf_attach_type expected_attach_type; /* For some prog types */
u32 len; /* Number of filter blocks */
u32 jited_len; /* Size of jited insns in bytes */
- u8 tag[BPF_TAG_SIZE];
+ union {
+ u8 digest[SHA256_DIGEST_SIZE];
+ u8 tag[BPF_TAG_SIZE];
+ };
struct bpf_prog_stats __percpu *stats;
int __percpu *active;
unsigned int (*bpf_func)(const void *ctx,
diff --git a/include/linux/filter.h b/include/linux/filter.h
index 1e7fd3ee759e..1bcc81ab3227 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -997,12 +997,6 @@ static inline u32 bpf_prog_insn_size(const struct bpf_prog *prog)
return prog->len * sizeof(struct bpf_insn);
}
-static inline u32 bpf_prog_tag_scratch_size(const struct bpf_prog *prog)
-{
- return round_up(bpf_prog_insn_size(prog) +
- sizeof(__be64) + 1, SHA1_BLOCK_SIZE);
-}
-
static inline unsigned int bpf_prog_size(unsigned int proglen)
{
return max(sizeof(struct bpf_prog),
diff --git a/kernel/bpf/Kconfig b/kernel/bpf/Kconfig
index 17067dcb4386..eb3de35734f0 100644
--- a/kernel/bpf/Kconfig
+++ b/kernel/bpf/Kconfig
@@ -3,7 +3,7 @@
# BPF interpreter that, for example, classic socket filters depend on.
config BPF
bool
- select CRYPTO_LIB_SHA1
+ select CRYPTO_LIB_SHA256
# Used by archs to tell that they support BPF JIT compiler plus which
# flavour. Only one of the two can be selected for a specific arch since
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 5d1650af899d..d1a7ea759c82 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -38,6 +38,7 @@
#include <linux/bpf_mem_alloc.h>
#include <linux/memcontrol.h>
#include <linux/execmem.h>
+#include <crypto/sha2.h>
#include <asm/barrier.h>
#include <linux/unaligned.h>
@@ -293,28 +294,18 @@ void __bpf_prog_free(struct bpf_prog *fp)
int bpf_prog_calc_tag(struct bpf_prog *fp)
{
- const u32 bits_offset = SHA1_BLOCK_SIZE - sizeof(__be64);
- u32 raw_size = bpf_prog_tag_scratch_size(fp);
- u32 digest[SHA1_DIGEST_WORDS];
- u32 ws[SHA1_WORKSPACE_WORDS];
- u32 i, bsize, psize, blocks;
+ u32 insn_size = bpf_prog_insn_size(fp);
struct bpf_insn *dst;
bool was_ld_map;
- u8 *raw, *todo;
- __be32 *result;
- __be64 *bits;
+ int i, ret = 0;
- raw = vmalloc(raw_size);
- if (!raw)
+ dst = vmalloc(insn_size);
+ if (!dst)
return -ENOMEM;
- sha1_init_raw(digest);
- memset(ws, 0, sizeof(ws));
-
/* We need to take out the map fd for the digest calculation
* since they are unstable from user space side.
*/
- dst = (void *)raw;
for (i = 0, was_ld_map = false; i < fp->len; i++) {
dst[i] = fp->insnsi[i];
if (!was_ld_map &&
@@ -334,34 +325,9 @@ int bpf_prog_calc_tag(struct bpf_prog *fp)
was_ld_map = false;
}
}
-
- psize = bpf_prog_insn_size(fp);
- memset(&raw[psize], 0, raw_size - psize);
- raw[psize++] = 0x80;
-
- bsize = round_up(psize, SHA1_BLOCK_SIZE);
- blocks = bsize / SHA1_BLOCK_SIZE;
- todo = raw;
- if (bsize - psize >= sizeof(__be64)) {
- bits = (__be64 *)(todo + bsize - sizeof(__be64));
- } else {
- bits = (__be64 *)(todo + bsize + bits_offset);
- blocks++;
- }
- *bits = cpu_to_be64((psize - 1) << 3);
-
- while (blocks--) {
- sha1_transform(digest, todo, ws);
- todo += SHA1_BLOCK_SIZE;
- }
-
- result = (__force __be32 *)digest;
- for (i = 0; i < SHA1_DIGEST_WORDS; i++)
- result[i] = cpu_to_be32(digest[i]);
- memcpy(fp->tag, result, sizeof(fp->tag));
-
- vfree(raw);
- return 0;
+ sha256((u8 *)dst, insn_size, fp->digest);
+ vfree(dst);
+ return ret;
}
static int bpf_adj_delta_to_imm(struct bpf_insn *insn, u32 pos, s32 end_old,
--
2.43.0
^ permalink raw reply related
* [PATCH v3 02/12] bpf: Implement exclusive map creation
From: KP Singh @ 2025-08-13 20:55 UTC (permalink / raw)
To: bpf, linux-security-module
Cc: bboscaccy, paul, kys, ast, daniel, andrii, KP Singh
In-Reply-To: <20250813205526.2992911-1-kpsingh@kernel.org>
Exclusive maps allow maps to only be accessed by program with a
program with a matching hash which is specified in the excl_prog_hash
attr.
For the signing use-case, this allows the trusted loader program
to load the map and verify the integrity
Signed-off-by: KP Singh <kpsingh@kernel.org>
---
include/linux/bpf.h | 1 +
include/uapi/linux/bpf.h | 2 ++
kernel/bpf/syscall.c | 32 ++++++++++++++++++++++++++++----
kernel/bpf/verifier.c | 6 ++++++
tools/include/uapi/linux/bpf.h | 2 ++
5 files changed, 39 insertions(+), 4 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index b98c5b5bf2a1..b23804733f2f 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -329,6 +329,7 @@ struct bpf_map {
atomic64_t sleepable_refcnt;
s64 __percpu *elem_count;
u64 cookie; /* write-once */
+ char *excl_prog_sha;
};
static inline const char *btf_field_type_name(enum btf_field_type type)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 233de8677382..7873ba7b9468 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1522,6 +1522,8 @@ union bpf_attr {
* If provided, map_flags should have BPF_F_TOKEN_FD flag set.
*/
__s32 map_token_fd;
+ __u32 excl_prog_hash_size;
+ __aligned_u64 excl_prog_hash;
};
struct { /* anonymous struct used by BPF_MAP_*_ELEM and BPF_MAP_FREEZE commands */
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 0fbfa8532c39..943811165510 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -860,6 +860,7 @@ static void bpf_map_free(struct bpf_map *map)
* the free of values or special fields allocated from bpf memory
* allocator.
*/
+ kfree(map->excl_prog_sha);
migrate_disable();
map->ops->map_free(map);
migrate_enable();
@@ -1338,9 +1339,9 @@ static bool bpf_net_capable(void)
return capable(CAP_NET_ADMIN) || capable(CAP_SYS_ADMIN);
}
-#define BPF_MAP_CREATE_LAST_FIELD map_token_fd
+#define BPF_MAP_CREATE_LAST_FIELD excl_prog_hash
/* called via syscall */
-static int map_create(union bpf_attr *attr, bool kernel)
+static int map_create(union bpf_attr *attr, bpfptr_t uattr)
{
const struct bpf_map_ops *ops;
struct bpf_token *token = NULL;
@@ -1534,7 +1535,30 @@ static int map_create(union bpf_attr *attr, bool kernel)
attr->btf_vmlinux_value_type_id;
}
- err = security_bpf_map_create(map, attr, token, kernel);
+ if (attr->excl_prog_hash) {
+ bpfptr_t uprog_hash = make_bpfptr(attr->excl_prog_hash, uattr.is_kernel);
+
+ if (attr->excl_prog_hash_size != SHA256_DIGEST_SIZE) {
+ err = -EINVAL;
+ goto free_map;
+ }
+
+ map->excl_prog_sha = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL);
+ if (!map->excl_prog_sha) {
+ err = -ENOMEM;
+ goto free_map;
+ }
+
+ if (copy_from_bpfptr(map->excl_prog_sha, uprog_hash,
+ SHA256_DIGEST_SIZE)) {
+ err = -EFAULT;
+ goto free_map;
+ }
+ } else if (attr->excl_prog_hash_size) {
+ return -EINVAL;
+ }
+
+ err = security_bpf_map_create(map, attr, token, uattr.is_kernel);
if (err)
goto free_map_sec;
@@ -6008,7 +6032,7 @@ static int __sys_bpf(enum bpf_cmd cmd, bpfptr_t uattr, unsigned int size)
switch (cmd) {
case BPF_MAP_CREATE:
- err = map_create(&attr, uattr.is_kernel);
+ err = map_create(&attr, uattr);
break;
case BPF_MAP_LOOKUP_ELEM:
err = map_lookup_elem(&attr);
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 3a3982fe20d4..2dd4449b946b 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -20360,6 +20360,12 @@ static int check_map_prog_compatibility(struct bpf_verifier_env *env,
{
enum bpf_prog_type prog_type = resolve_prog_type(prog);
+ if (map->excl_prog_sha &&
+ memcmp(map->excl_prog_sha, prog->digest, SHA256_DIGEST_SIZE)) {
+ verbose(env, "program's hash doesn't match map's excl_prog_hash\n");
+ return -EACCES;
+ }
+
if (btf_record_has_field(map->record, BPF_LIST_HEAD) ||
btf_record_has_field(map->record, BPF_RB_ROOT)) {
if (is_tracing_prog_type(prog_type)) {
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 233de8677382..7873ba7b9468 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1522,6 +1522,8 @@ union bpf_attr {
* If provided, map_flags should have BPF_F_TOKEN_FD flag set.
*/
__s32 map_token_fd;
+ __u32 excl_prog_hash_size;
+ __aligned_u64 excl_prog_hash;
};
struct { /* anonymous struct used by BPF_MAP_*_ELEM and BPF_MAP_FREEZE commands */
--
2.43.0
^ permalink raw reply related
* [PATCH v3 03/12] libbpf: Implement SHA256 internal helper
From: KP Singh @ 2025-08-13 20:55 UTC (permalink / raw)
To: bpf, linux-security-module
Cc: bboscaccy, paul, kys, ast, daniel, andrii, KP Singh
In-Reply-To: <20250813205526.2992911-1-kpsingh@kernel.org>
Use AF_ALG sockets to not have libbpf depend on OpenSSL. The helper is
used for the loader generation code to embed the metadata hash in the
loader program and also by the bpf_map__make_exclusive API to calculate
the hash of the program the map is exclusive to.
Signed-off-by: KP Singh <kpsingh@kernel.org>
---
tools/lib/bpf/libbpf.c | 59 +++++++++++++++++++++++++++++++++
tools/lib/bpf/libbpf_internal.h | 4 +++
2 files changed, 63 insertions(+)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 8f5a81b672e1..0bb3d71dcd9f 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -43,6 +43,9 @@
#include <sys/vfs.h>
#include <sys/utsname.h>
#include <sys/resource.h>
+#include <sys/socket.h>
+#include <linux/if_alg.h>
+#include <linux/socket.h>
#include <libelf.h>
#include <gelf.h>
#include <zlib.h>
@@ -14207,3 +14210,59 @@ void bpf_object__destroy_skeleton(struct bpf_object_skeleton *s)
free(s->progs);
free(s);
}
+
+int libbpf_sha256(const void *data, size_t data_sz, void *sha_out, size_t sha_out_sz)
+{
+ struct sockaddr_alg sa = {
+ .salg_family = AF_ALG,
+ .salg_type = "hash",
+ .salg_name = "sha256"
+ };
+ int sock_fd = -1;
+ int op_fd = -1;
+ int err = 0;
+
+ if (sha_out_sz != SHA256_DIGEST_LENGTH) {
+ pr_warn("sha_out_sz should be exactly 32 bytes for a SHA256 digest");
+ return libbpf_err(-EINVAL);
+ }
+
+ sock_fd = socket(AF_ALG, SOCK_SEQPACKET, 0);
+ if (sock_fd < 0) {
+ err = -errno;
+ pr_warn("failed to create AF_ALG socket for SHA256: %s\n", errstr(err));
+ return libbpf_err(err);
+ }
+
+ if (bind(sock_fd, (struct sockaddr *)&sa, sizeof(sa)) < 0) {
+ err = -errno;
+ pr_warn("failed to bind to AF_ALG socket for SHA256: %s\n", errstr(err));
+ goto out;
+ }
+
+ op_fd = accept(sock_fd, NULL, 0);
+ if (op_fd < 0) {
+ err = -errno;
+ pr_warn("failed to accept from AF_ALG socket for SHA256: %s\n", errstr(err));
+ goto out;
+ }
+
+ if (write(op_fd, data, data_sz) != data_sz) {
+ err = -errno;
+ pr_warn("failed to write data to AF_ALG socket for SHA256: %s\n", errstr(err));
+ goto out;
+ }
+
+ if (read(op_fd, sha_out, SHA256_DIGEST_LENGTH) != SHA256_DIGEST_LENGTH) {
+ err = -errno;
+ pr_warn("failed to read SHA256 from AF_ALG socket: %s\n", errstr(err));
+ goto out;
+ }
+
+out:
+ if (op_fd >= 0)
+ close(op_fd);
+ if (sock_fd >= 0)
+ close(sock_fd);
+ return libbpf_err(err);
+}
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index 477a3b3389a0..8a055de0d324 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -736,4 +736,8 @@ int elf_resolve_pattern_offsets(const char *binary_path, const char *pattern,
int probe_fd(int fd);
+#define SHA256_DIGEST_LENGTH 32
+#define SHA256_DWORD_SIZE SHA256_DIGEST_LENGTH / sizeof(__u64)
+
+int libbpf_sha256(const void *data, size_t data_sz, void *sha_out, size_t sha_out_sz);
#endif /* __LIBBPF_LIBBPF_INTERNAL_H */
--
2.43.0
^ permalink raw reply related
* [PATCH v3 04/12] libbpf: Support exclusive map creation
From: KP Singh @ 2025-08-13 20:55 UTC (permalink / raw)
To: bpf, linux-security-module
Cc: bboscaccy, paul, kys, ast, daniel, andrii, KP Singh
In-Reply-To: <20250813205526.2992911-1-kpsingh@kernel.org>
Implement setters and getters that allow map to be registers as
exclusive to the specified program. The registration should be done
before the exclusive program is loaded.
Signed-off-by: KP Singh <kpsingh@kernel.org>
---
tools/lib/bpf/bpf.c | 4 ++-
tools/lib/bpf/bpf.h | 4 ++-
tools/lib/bpf/libbpf.c | 66 ++++++++++++++++++++++++++++++++++++++++
tools/lib/bpf/libbpf.h | 18 +++++++++++
tools/lib/bpf/libbpf.map | 2 ++
5 files changed, 92 insertions(+), 2 deletions(-)
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index ab40dbf9f020..6a08a1559237 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -172,7 +172,7 @@ int bpf_map_create(enum bpf_map_type map_type,
__u32 max_entries,
const struct bpf_map_create_opts *opts)
{
- const size_t attr_sz = offsetofend(union bpf_attr, map_token_fd);
+ const size_t attr_sz = offsetofend(union bpf_attr, excl_prog_hash);
union bpf_attr attr;
int fd;
@@ -203,6 +203,8 @@ int bpf_map_create(enum bpf_map_type map_type,
attr.map_ifindex = OPTS_GET(opts, map_ifindex, 0);
attr.map_token_fd = OPTS_GET(opts, token_fd, 0);
+ attr.excl_prog_hash = ptr_to_u64(OPTS_GET(opts, excl_prog_hash, NULL));
+ attr.excl_prog_hash_size = OPTS_GET(opts, excl_prog_hash_size, 0);
fd = sys_bpf_fd(BPF_MAP_CREATE, &attr, attr_sz);
return libbpf_err_errno(fd);
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 7252150e7ad3..675a09bb7d2f 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -54,9 +54,11 @@ struct bpf_map_create_opts {
__s32 value_type_btf_obj_fd;
__u32 token_fd;
+ __u32 excl_prog_hash_size;
+ const void *excl_prog_hash;
size_t :0;
};
-#define bpf_map_create_opts__last_field token_fd
+#define bpf_map_create_opts__last_field excl_prog_hash
LIBBPF_API int bpf_map_create(enum bpf_map_type map_type,
const char *map_name,
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 0bb3d71dcd9f..ed3294f69271 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -499,6 +499,7 @@ struct bpf_program {
__u32 line_info_rec_size;
__u32 line_info_cnt;
__u32 prog_flags;
+ __u8 hash[SHA256_DIGEST_LENGTH];
};
struct bpf_struct_ops {
@@ -578,6 +579,7 @@ struct bpf_map {
bool autocreate;
bool autoattach;
__u64 map_extra;
+ struct bpf_program *excl_prog;
};
enum extern_type {
@@ -4488,6 +4490,43 @@ bpf_object__section_to_libbpf_map_type(const struct bpf_object *obj, int shndx)
}
}
+static int bpf_program__compute_hash(struct bpf_program *prog)
+{
+ struct bpf_insn *purged;
+ int i, err;
+
+ purged = calloc(1, BPF_INSN_SZ * prog->insns_cnt);
+ if (!purged)
+ return -ENOMEM;
+
+ /* If relocations have been done, the map_fd needs to be
+ * discarded for the digest calculation.
+ */
+ for (i = 0; i < prog->insns_cnt; i++) {
+ purged[i] = prog->insns[i];
+ if (purged[i].code == (BPF_LD | BPF_IMM | BPF_DW) &&
+ (purged[i].src_reg == BPF_PSEUDO_MAP_FD ||
+ purged[i].src_reg == BPF_PSEUDO_MAP_VALUE)) {
+ purged[i].imm = 0;
+ i++;
+ if (i >= prog->insns_cnt ||
+ prog->insns[i].code != 0 ||
+ prog->insns[i].dst_reg != 0 ||
+ prog->insns[i].src_reg != 0 ||
+ prog->insns[i].off != 0) {
+ err = -EINVAL;
+ goto out;
+ }
+ purged[i] = prog->insns[i];
+ purged[i].imm = 0;
+ }
+ }
+ err = libbpf_sha256(purged, prog->insns_cnt * sizeof(struct bpf_insn), prog->hash, SHA256_DIGEST_LENGTH);
+out:
+ free(purged);
+ return err;
+}
+
static int bpf_program__record_reloc(struct bpf_program *prog,
struct reloc_desc *reloc_desc,
__u32 insn_idx, const char *sym_name,
@@ -5227,6 +5266,18 @@ static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map, b
create_attr.token_fd = obj->token_fd;
if (obj->token_fd)
create_attr.map_flags |= BPF_F_TOKEN_FD;
+ if (map->excl_prog) {
+ if (map->excl_prog->obj->state == OBJ_LOADED) {
+ pr_warn("exclusive program already loaded\n");
+ return libbpf_err(-EINVAL);
+ }
+ err = bpf_program__compute_hash(map->excl_prog);
+ if (err)
+ return err;
+
+ create_attr.excl_prog_hash = map->excl_prog->hash;
+ create_attr.excl_prog_hash_size = SHA256_DIGEST_LENGTH;
+ }
if (bpf_map__is_struct_ops(map)) {
create_attr.btf_vmlinux_value_type_id = map->btf_vmlinux_value_type_id;
@@ -10517,6 +10568,21 @@ int bpf_map__set_inner_map_fd(struct bpf_map *map, int fd)
return 0;
}
+int bpf_map__set_exclusive_program(struct bpf_map *map, struct bpf_program *prog)
+{
+ if (map_is_created(map)) {
+ pr_warn("exclusive programs must be set before map creation\n");
+ return libbpf_err(-EINVAL);
+ }
+ map->excl_prog = prog;
+ return 0;
+}
+
+struct bpf_program *bpf_map__get_exclusive_program(struct bpf_map *map)
+{
+ return map->excl_prog;
+}
+
static struct bpf_map *
__bpf_map__iter(const struct bpf_map *m, const struct bpf_object *obj, int i)
{
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 455a957cb702..ddaf58c8a298 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -1266,7 +1266,25 @@ LIBBPF_API int bpf_map__lookup_and_delete_elem(const struct bpf_map *map,
*/
LIBBPF_API int bpf_map__get_next_key(const struct bpf_map *map,
const void *cur_key, void *next_key, size_t key_sz);
+/**
+ * @brief **bpf_map__set_exclusive_program()** sets map to be exclusive to the
+ * to the specified program. The program must not be loaded yet.
+ * @param map BPF map to make exclusive.
+ * @param prog BPF program to be the exclusive user of the map.
+ * @return 0 on success; a negative error code otherwise.
+ *
+ * Once a map is made exclusive, only the specified program can access its
+ * contents.
+ */
+LIBBPF_API int bpf_map__set_exclusive_program(struct bpf_map *map, struct bpf_program *prog);
+/**
+ * @brief **bpf_map__get_exclusive_program()** returns the exclusive program
+ * that is registered with the map (if any).
+ * @param map BPF map to which the exclusive program is registered.
+ * @return the registered exclusive program.
+ */
+LIBBPF_API struct bpf_program *bpf_map__get_exclusive_program(struct bpf_map *map);
struct bpf_xdp_set_link_opts {
size_t sz;
int old_fd;
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index d7bd463e7017..a5c5d0f2db5c 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -436,6 +436,8 @@ LIBBPF_1.6.0 {
bpf_linker__add_buf;
bpf_linker__add_fd;
bpf_linker__new_fd;
+ bpf_map__set_exclusive_program;
+ bpf_map__get_exclusive_program;
bpf_object__prepare;
bpf_prog_stream_read;
bpf_program__attach_cgroup_opts;
--
2.43.0
^ permalink raw reply related
* [PATCH v3 05/12] selftests/bpf: Add tests for exclusive maps
From: KP Singh @ 2025-08-13 20:55 UTC (permalink / raw)
To: bpf, linux-security-module
Cc: bboscaccy, paul, kys, ast, daniel, andrii, KP Singh
In-Reply-To: <20250813205526.2992911-1-kpsingh@kernel.org>
Check if access is denied to another program for an exclusive map
Signed-off-by: KP Singh <kpsingh@kernel.org>
---
.../selftests/bpf/prog_tests/map_excl.c | 56 +++++++++++++++++++
tools/testing/selftests/bpf/progs/map_excl.c | 34 +++++++++++
2 files changed, 90 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/map_excl.c
create mode 100644 tools/testing/selftests/bpf/progs/map_excl.c
diff --git a/tools/testing/selftests/bpf/prog_tests/map_excl.c b/tools/testing/selftests/bpf/prog_tests/map_excl.c
new file mode 100644
index 000000000000..7a49917c691a
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/map_excl.c
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2023. Huawei Technologies Co., Ltd */
+#define _GNU_SOURCE
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <test_progs.h>
+#include <bpf/btf.h>
+
+#include "map_excl.skel.h"
+
+static void test_map_excl_allowed(void)
+{
+ struct map_excl *skel = map_excl__open();
+ int err;
+
+ err = bpf_map__set_exclusive_program(skel->maps.excl_map, skel->progs.should_have_access);
+ if (!ASSERT_OK(err, "bpf_map__set_exclusive_program"))
+ goto out;
+
+ bpf_program__set_autoload(skel->progs.should_have_access, true);
+ bpf_program__set_autoload(skel->progs.should_not_have_access, false);
+
+ err = map_excl__load(skel);
+ ASSERT_OK(err, "map_excl__load");
+out:
+ map_excl__destroy(skel);
+}
+
+static void test_map_excl_denied(void)
+{
+ struct map_excl *skel = map_excl__open();
+ int err;
+
+ err = bpf_map__set_exclusive_program(skel->maps.excl_map, skel->progs.should_have_access);
+ if (!ASSERT_OK(err, "bpf_map__make_exclusive"))
+ goto out;
+
+ bpf_program__set_autoload(skel->progs.should_have_access, false);
+ bpf_program__set_autoload(skel->progs.should_not_have_access, true);
+
+ err = map_excl__load(skel);
+ ASSERT_EQ(err, -EACCES, "exclusive map Paccess not denied\n");
+out:
+ map_excl__destroy(skel);
+
+}
+
+void test_map_excl(void)
+{
+ start_libbpf_log_capture();
+ if (test__start_subtest("map_excl_allowed"))
+ test_map_excl_allowed();
+ stop_libbpf_log_capture();
+ if (test__start_subtest("map_excl_denied"))
+ test_map_excl_denied();
+}
diff --git a/tools/testing/selftests/bpf/progs/map_excl.c b/tools/testing/selftests/bpf/progs/map_excl.c
new file mode 100644
index 000000000000..26c32b4f2ce0
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/map_excl.c
@@ -0,0 +1,34 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2023. Huawei Technologies Co., Ltd */
+#include <linux/bpf.h>
+#include <time.h>
+#include <bpf/bpf_helpers.h>
+
+#include "bpf_misc.h"
+
+struct {
+ __uint(type, BPF_MAP_TYPE_ARRAY);
+ __type(key, __u32);
+ __type(value, __u32);
+ __uint(max_entries, 1);
+} excl_map SEC(".maps");
+
+char _license[] SEC("license") = "GPL";
+
+SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
+int should_have_access(void *ctx)
+{
+ int key = 0, value = 0xdeadbeef;
+
+ bpf_map_update_elem(&excl_map, &key, &value, 0);
+ return 0;
+}
+
+SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
+int should_not_have_access(void *ctx)
+{
+ int key = 0, value = 0xdeadbeef;
+
+ bpf_map_update_elem(&excl_map, &key, &value, 0);
+ return 0;
+}
--
2.43.0
^ permalink raw reply related
* [PATCH v3 06/12] bpf: Return hashes of maps in BPF_OBJ_GET_INFO_BY_FD
From: KP Singh @ 2025-08-13 20:55 UTC (permalink / raw)
To: bpf, linux-security-module
Cc: bboscaccy, paul, kys, ast, daniel, andrii, KP Singh
In-Reply-To: <20250813205526.2992911-1-kpsingh@kernel.org>
Currently only array maps are supported, but the implementation can be
extended for other maps and objects. The hash is memoized only for
exclusive and frozen maps as their content is stable until the exclusive
program modifies the map.
This is required for BPF signing, enabling a trusted loader program to
verify a map's integrity. The loader retrieves
the map's runtime hash from the kernel and compares it against an
expected hash computed at build time.
Signed-off-by: KP Singh <kpsingh@kernel.org>
---
include/linux/bpf.h | 3 +++
include/uapi/linux/bpf.h | 2 ++
kernel/bpf/arraymap.c | 13 +++++++++++
kernel/bpf/syscall.c | 23 +++++++++++++++++++
tools/include/uapi/linux/bpf.h | 2 ++
.../selftests/bpf/progs/verifier_map_ptr.c | 7 ++++--
6 files changed, 48 insertions(+), 2 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index b23804733f2f..b12a0645c2a3 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -7,6 +7,7 @@
#include <uapi/linux/bpf.h>
#include <uapi/linux/filter.h>
+#include <crypto/sha2.h>
#include <linux/workqueue.h>
#include <linux/file.h>
#include <linux/percpu.h>
@@ -110,6 +111,7 @@ struct bpf_map_ops {
long (*map_pop_elem)(struct bpf_map *map, void *value);
long (*map_peek_elem)(struct bpf_map *map, void *value);
void *(*map_lookup_percpu_elem)(struct bpf_map *map, void *key, u32 cpu);
+ int (*map_get_hash)(struct bpf_map *map, u32 hash_buf_size, void *hash_buf);
/* funcs called by prog_array and perf_event_array map */
void *(*map_fd_get_ptr)(struct bpf_map *map, struct file *map_file,
@@ -289,6 +291,7 @@ struct bpf_map_owner {
};
struct bpf_map {
+ u8 sha[SHA256_DIGEST_SIZE];
const struct bpf_map_ops *ops;
struct bpf_map *inner_map_meta;
#ifdef CONFIG_SECURITY
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 7873ba7b9468..fd3b895ebebf 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -6668,6 +6668,8 @@ struct bpf_map_info {
__u32 btf_value_type_id;
__u32 btf_vmlinux_id;
__u64 map_extra;
+ __aligned_u64 hash;
+ __u32 hash_size;
} __attribute__((aligned(8)));
struct bpf_btf_info {
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 3d080916faf9..26d5dda989bc 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -12,6 +12,7 @@
#include <uapi/linux/btf.h>
#include <linux/rcupdate_trace.h>
#include <linux/btf_ids.h>
+#include <crypto/sha2.h>
#include "map_in_map.h"
@@ -174,6 +175,17 @@ static void *array_map_lookup_elem(struct bpf_map *map, void *key)
return array->value + (u64)array->elem_size * (index & array->index_mask);
}
+static int array_map_get_hash(struct bpf_map *map, u32 hash_buf_size,
+ void *hash_buf)
+{
+ struct bpf_array *array = container_of(map, struct bpf_array, map);
+
+ sha256(array->value, (u64)array->elem_size * array->map.max_entries,
+ hash_buf);
+ memcpy(array->map.sha, hash_buf, sizeof(array->map.sha));
+ return 0;
+}
+
static int array_map_direct_value_addr(const struct bpf_map *map, u64 *imm,
u32 off)
{
@@ -800,6 +812,7 @@ const struct bpf_map_ops array_map_ops = {
.map_mem_usage = array_map_mem_usage,
.map_btf_id = &array_map_btf_ids[0],
.iter_seq_info = &iter_seq_info,
+ .map_get_hash = &array_map_get_hash,
};
const struct bpf_map_ops percpu_array_map_ops = {
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 943811165510..3d99c443ab7a 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
*/
+#include <crypto/sha2.h>
#include <linux/bpf.h>
#include <linux/bpf-cgroup.h>
#include <linux/bpf_trace.h>
@@ -5185,6 +5186,9 @@ static int bpf_map_get_info_by_fd(struct file *file,
info_len = min_t(u32, sizeof(info), info_len);
memset(&info, 0, sizeof(info));
+ if (copy_from_user(&info, uinfo, info_len))
+ return -EFAULT;
+
info.type = map->map_type;
info.id = map->id;
info.key_size = map->key_size;
@@ -5209,6 +5213,25 @@ static int bpf_map_get_info_by_fd(struct file *file,
return err;
}
+ if (info.hash) {
+ char __user *uhash = u64_to_user_ptr(info.hash);
+
+ if (!map->ops->map_get_hash)
+ return -EINVAL;
+
+ if (info.hash_size != SHA256_DIGEST_SIZE)
+ return -EINVAL;
+
+ err = map->ops->map_get_hash(map, SHA256_DIGEST_SIZE, map->sha);
+ if (err != 0)
+ return err;
+
+ if (copy_to_user(uhash, map->sha, SHA256_DIGEST_SIZE) != 0)
+ return -EFAULT;
+ } else if (info.hash_size) {
+ return -EINVAL;
+ }
+
if (copy_to_user(uinfo, &info, info_len) ||
put_user(info_len, &uattr->info.info_len))
return -EFAULT;
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 7873ba7b9468..fd3b895ebebf 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -6668,6 +6668,8 @@ struct bpf_map_info {
__u32 btf_value_type_id;
__u32 btf_vmlinux_id;
__u64 map_extra;
+ __aligned_u64 hash;
+ __u32 hash_size;
} __attribute__((aligned(8)));
struct bpf_btf_info {
diff --git a/tools/testing/selftests/bpf/progs/verifier_map_ptr.c b/tools/testing/selftests/bpf/progs/verifier_map_ptr.c
index 11a079145966..e2767d27d8aa 100644
--- a/tools/testing/selftests/bpf/progs/verifier_map_ptr.c
+++ b/tools/testing/selftests/bpf/progs/verifier_map_ptr.c
@@ -70,10 +70,13 @@ __naked void bpf_map_ptr_write_rejected(void)
: __clobber_all);
}
+/* The first element of struct bpf_map is a SHA256 hash of 32 bytes, accessing
+ * into this array is valid. The opts field is now at offset 33.
+ */
SEC("socket")
__description("bpf_map_ptr: read non-existent field rejected")
__failure
-__msg("cannot access ptr member ops with moff 0 in struct bpf_map with off 1 size 4")
+__msg("cannot access ptr member ops with moff 32 in struct bpf_map with off 33 size 4")
__failure_unpriv
__msg_unpriv("access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN")
__flag(BPF_F_ANY_ALIGNMENT)
@@ -82,7 +85,7 @@ __naked void read_non_existent_field_rejected(void)
asm volatile (" \
r6 = 0; \
r1 = %[map_array_48b] ll; \
- r6 = *(u32*)(r1 + 1); \
+ r6 = *(u32*)(r1 + 33); \
r0 = 1; \
exit; \
" :
--
2.43.0
^ permalink raw reply related
* [PATCH v3 07/12] bpf: Move the signature kfuncs to helpers.c
From: KP Singh @ 2025-08-13 20:55 UTC (permalink / raw)
To: bpf, linux-security-module
Cc: bboscaccy, paul, kys, ast, daniel, andrii, KP Singh
In-Reply-To: <20250813205526.2992911-1-kpsingh@kernel.org>
No functional changes, except for the addition of the headers for the
kfuncs so that they can be used for signature verification.
Signed-off-by: KP Singh <kpsingh@kernel.org>
---
include/linux/bpf.h | 32 +++++++
kernel/bpf/helpers.c | 166 +++++++++++++++++++++++++++++++++++
kernel/trace/bpf_trace.c | 183 ---------------------------------------
3 files changed, 198 insertions(+), 183 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index b12a0645c2a3..809a1c6882f1 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -3412,6 +3412,38 @@ static inline int bpf_fd_reuseport_array_update_elem(struct bpf_map *map,
#endif /* CONFIG_BPF_SYSCALL */
#endif /* defined(CONFIG_INET) && defined(CONFIG_BPF_SYSCALL) */
+#if defined(CONFIG_KEYS) && defined(CONFIG_BPF_SYSCALL)
+
+struct bpf_key *bpf_lookup_user_key(s32 serial, u64 flags);
+struct bpf_key *bpf_lookup_system_key(u64 id);
+void bpf_key_put(struct bpf_key *bkey);
+int bpf_verify_pkcs7_signature(struct bpf_dynptr *data_p,
+ struct bpf_dynptr *sig_p,
+ struct bpf_key *trusted_keyring);
+
+#else
+static inline struct bpf_key *bpf_lookup_user_key(u32 serial, u64 flags)
+{
+ return NULL;
+}
+
+static inline struct bpf_key *bpf_lookup_system_key(u64 id)
+{
+ return NULL;
+}
+
+static inline void bpf_key_put(struct bpf_key *bkey)
+{
+}
+
+static inline int bpf_verify_pkcs7_signature(struct bpf_dynptr *data_p,
+ struct bpf_dynptr *sig_p,
+ struct bpf_key *trusted_keyring)
+{
+ return -EOPNOTSUPP;
+}
+#endif /* defined(CONFIG_KEYS) && defined(CONFIG_BPF_SYSCALL) */
+
/* verifier prototypes for helper functions called from eBPF programs */
extern const struct bpf_func_proto bpf_map_lookup_elem_proto;
extern const struct bpf_func_proto bpf_map_update_elem_proto;
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 6b4877e85a68..a052bbbcbfc5 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -25,6 +25,7 @@
#include <linux/kasan.h>
#include <linux/bpf_verifier.h>
#include <linux/uaccess.h>
+#include <linux/verification.h>
#include "../../lib/kstrtox.h"
@@ -3702,6 +3703,163 @@ __bpf_kfunc int bpf_strstr(const char *s1__ign, const char *s2__ign)
{
return bpf_strnstr(s1__ign, s2__ign, XATTR_SIZE_MAX);
}
+#ifdef CONFIG_KEYS
+/**
+ * bpf_lookup_user_key - lookup a key by its serial
+ * @serial: key handle serial number
+ * @flags: lookup-specific flags
+ *
+ * Search a key with a given *serial* and the provided *flags*.
+ * If found, increment the reference count of the key by one, and
+ * return it in the bpf_key structure.
+ *
+ * The bpf_key structure must be passed to bpf_key_put() when done
+ * with it, so that the key reference count is decremented and the
+ * bpf_key structure is freed.
+ *
+ * Permission checks are deferred to the time the key is used by
+ * one of the available key-specific kfuncs.
+ *
+ * Set *flags* with KEY_LOOKUP_CREATE, to attempt creating a requested
+ * special keyring (e.g. session keyring), if it doesn't yet exist.
+ * Set *flags* with KEY_LOOKUP_PARTIAL, to lookup a key without waiting
+ * for the key construction, and to retrieve uninstantiated keys (keys
+ * without data attached to them).
+ *
+ * Return: a bpf_key pointer with a valid key pointer if the key is found, a
+ * NULL pointer otherwise.
+ */
+__bpf_kfunc struct bpf_key *bpf_lookup_user_key(s32 serial, u64 flags)
+{
+ key_ref_t key_ref;
+ struct bpf_key *bkey;
+
+ if (flags & ~KEY_LOOKUP_ALL)
+ return NULL;
+
+ /*
+ * Permission check is deferred until the key is used, as the
+ * intent of the caller is unknown here.
+ */
+ key_ref = lookup_user_key(serial, flags, KEY_DEFER_PERM_CHECK);
+ if (IS_ERR(key_ref))
+ return NULL;
+
+ bkey = kmalloc(sizeof(*bkey), GFP_KERNEL);
+ if (!bkey) {
+ key_put(key_ref_to_ptr(key_ref));
+ return NULL;
+ }
+
+ bkey->key = key_ref_to_ptr(key_ref);
+ bkey->has_ref = true;
+
+ return bkey;
+}
+
+/**
+ * bpf_lookup_system_key - lookup a key by a system-defined ID
+ * @id: key ID
+ *
+ * Obtain a bpf_key structure with a key pointer set to the passed key ID.
+ * The key pointer is marked as invalid, to prevent bpf_key_put() from
+ * attempting to decrement the key reference count on that pointer. The key
+ * pointer set in such way is currently understood only by
+ * verify_pkcs7_signature().
+ *
+ * Set *id* to one of the values defined in include/linux/verification.h:
+ * 0 for the primary keyring (immutable keyring of system keys);
+ * VERIFY_USE_SECONDARY_KEYRING for both the primary and secondary keyring
+ * (where keys can be added only if they are vouched for by existing keys
+ * in those keyrings); VERIFY_USE_PLATFORM_KEYRING for the platform
+ * keyring (primarily used by the integrity subsystem to verify a kexec'ed
+ * kerned image and, possibly, the initramfs signature).
+ *
+ * Return: a bpf_key pointer with an invalid key pointer set from the
+ * pre-determined ID on success, a NULL pointer otherwise
+ */
+__bpf_kfunc struct bpf_key *bpf_lookup_system_key(u64 id)
+{
+ struct bpf_key *bkey;
+
+ if (system_keyring_id_check(id) < 0)
+ return NULL;
+
+ bkey = kmalloc(sizeof(*bkey), GFP_ATOMIC);
+ if (!bkey)
+ return NULL;
+
+ bkey->key = (struct key *)(unsigned long)id;
+ bkey->has_ref = false;
+
+ return bkey;
+}
+
+/**
+ * bpf_key_put - decrement key reference count if key is valid and free bpf_key
+ * @bkey: bpf_key structure
+ *
+ * Decrement the reference count of the key inside *bkey*, if the pointer
+ * is valid, and free *bkey*.
+ */
+__bpf_kfunc void bpf_key_put(struct bpf_key *bkey)
+{
+ if (bkey->has_ref)
+ key_put(bkey->key);
+
+ kfree(bkey);
+}
+
+/**
+ * bpf_verify_pkcs7_signature - verify a PKCS#7 signature
+ * @data_p: data to verify
+ * @sig_p: signature of the data
+ * @trusted_keyring: keyring with keys trusted for signature verification
+ *
+ * Verify the PKCS#7 signature *sig_ptr* against the supplied *data_ptr*
+ * with keys in a keyring referenced by *trusted_keyring*.
+ *
+ * Return: 0 on success, a negative value on error.
+ */
+__bpf_kfunc int bpf_verify_pkcs7_signature(struct bpf_dynptr *data_p,
+ struct bpf_dynptr *sig_p,
+ struct bpf_key *trusted_keyring)
+{
+#ifdef CONFIG_SYSTEM_DATA_VERIFICATION
+ struct bpf_dynptr_kern *data_ptr = (struct bpf_dynptr_kern *)data_p;
+ struct bpf_dynptr_kern *sig_ptr = (struct bpf_dynptr_kern *)sig_p;
+ const void *data, *sig;
+ u32 data_len, sig_len;
+ int ret;
+
+ if (trusted_keyring->has_ref) {
+ /*
+ * Do the permission check deferred in bpf_lookup_user_key().
+ * See bpf_lookup_user_key() for more details.
+ *
+ * A call to key_task_permission() here would be redundant, as
+ * it is already done by keyring_search() called by
+ * find_asymmetric_key().
+ */
+ ret = key_validate(trusted_keyring->key);
+ if (ret < 0)
+ return ret;
+ }
+
+ data_len = __bpf_dynptr_size(data_ptr);
+ data = __bpf_dynptr_data(data_ptr, data_len);
+ sig_len = __bpf_dynptr_size(sig_ptr);
+ sig = __bpf_dynptr_data(sig_ptr, sig_len);
+
+ return verify_pkcs7_signature(data, data_len, sig, sig_len,
+ trusted_keyring->key,
+ VERIFYING_UNSPECIFIED_SIGNATURE, NULL,
+ NULL);
+#else
+ return -EOPNOTSUPP;
+#endif /* CONFIG_SYSTEM_DATA_VERIFICATION */
+}
+#endif /* CONFIG_KEYS */
__bpf_kfunc_end_defs();
@@ -3743,6 +3901,14 @@ BTF_ID_FLAGS(func, bpf_throw)
#ifdef CONFIG_BPF_EVENTS
BTF_ID_FLAGS(func, bpf_send_signal_task, KF_TRUSTED_ARGS)
#endif
+#ifdef CONFIG_KEYS
+BTF_ID_FLAGS(func, bpf_lookup_user_key, KF_ACQUIRE | KF_RET_NULL | KF_SLEEPABLE)
+BTF_ID_FLAGS(func, bpf_lookup_system_key, KF_ACQUIRE | KF_RET_NULL)
+BTF_ID_FLAGS(func, bpf_key_put, KF_RELEASE)
+#ifdef CONFIG_SYSTEM_DATA_VERIFICATION
+BTF_ID_FLAGS(func, bpf_verify_pkcs7_signature, KF_SLEEPABLE)
+#endif
+#endif
BTF_KFUNCS_END(generic_btf_ids)
static const struct btf_kfunc_id_set generic_kfunc_set = {
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 3ae52978cae6..02c3f610420d 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -22,7 +22,6 @@
#include <linux/bsearch.h>
#include <linux/sort.h>
#include <linux/key.h>
-#include <linux/verification.h>
#include <linux/namei.h>
#include <net/bpf_sk_storage.h>
@@ -1241,188 +1240,6 @@ static const struct bpf_func_proto bpf_get_func_arg_cnt_proto = {
.arg1_type = ARG_PTR_TO_CTX,
};
-#ifdef CONFIG_KEYS
-__bpf_kfunc_start_defs();
-
-/**
- * bpf_lookup_user_key - lookup a key by its serial
- * @serial: key handle serial number
- * @flags: lookup-specific flags
- *
- * Search a key with a given *serial* and the provided *flags*.
- * If found, increment the reference count of the key by one, and
- * return it in the bpf_key structure.
- *
- * The bpf_key structure must be passed to bpf_key_put() when done
- * with it, so that the key reference count is decremented and the
- * bpf_key structure is freed.
- *
- * Permission checks are deferred to the time the key is used by
- * one of the available key-specific kfuncs.
- *
- * Set *flags* with KEY_LOOKUP_CREATE, to attempt creating a requested
- * special keyring (e.g. session keyring), if it doesn't yet exist.
- * Set *flags* with KEY_LOOKUP_PARTIAL, to lookup a key without waiting
- * for the key construction, and to retrieve uninstantiated keys (keys
- * without data attached to them).
- *
- * Return: a bpf_key pointer with a valid key pointer if the key is found, a
- * NULL pointer otherwise.
- */
-__bpf_kfunc struct bpf_key *bpf_lookup_user_key(s32 serial, u64 flags)
-{
- key_ref_t key_ref;
- struct bpf_key *bkey;
-
- if (flags & ~KEY_LOOKUP_ALL)
- return NULL;
-
- /*
- * Permission check is deferred until the key is used, as the
- * intent of the caller is unknown here.
- */
- key_ref = lookup_user_key(serial, flags, KEY_DEFER_PERM_CHECK);
- if (IS_ERR(key_ref))
- return NULL;
-
- bkey = kmalloc(sizeof(*bkey), GFP_KERNEL);
- if (!bkey) {
- key_put(key_ref_to_ptr(key_ref));
- return NULL;
- }
-
- bkey->key = key_ref_to_ptr(key_ref);
- bkey->has_ref = true;
-
- return bkey;
-}
-
-/**
- * bpf_lookup_system_key - lookup a key by a system-defined ID
- * @id: key ID
- *
- * Obtain a bpf_key structure with a key pointer set to the passed key ID.
- * The key pointer is marked as invalid, to prevent bpf_key_put() from
- * attempting to decrement the key reference count on that pointer. The key
- * pointer set in such way is currently understood only by
- * verify_pkcs7_signature().
- *
- * Set *id* to one of the values defined in include/linux/verification.h:
- * 0 for the primary keyring (immutable keyring of system keys);
- * VERIFY_USE_SECONDARY_KEYRING for both the primary and secondary keyring
- * (where keys can be added only if they are vouched for by existing keys
- * in those keyrings); VERIFY_USE_PLATFORM_KEYRING for the platform
- * keyring (primarily used by the integrity subsystem to verify a kexec'ed
- * kerned image and, possibly, the initramfs signature).
- *
- * Return: a bpf_key pointer with an invalid key pointer set from the
- * pre-determined ID on success, a NULL pointer otherwise
- */
-__bpf_kfunc struct bpf_key *bpf_lookup_system_key(u64 id)
-{
- struct bpf_key *bkey;
-
- if (system_keyring_id_check(id) < 0)
- return NULL;
-
- bkey = kmalloc(sizeof(*bkey), GFP_ATOMIC);
- if (!bkey)
- return NULL;
-
- bkey->key = (struct key *)(unsigned long)id;
- bkey->has_ref = false;
-
- return bkey;
-}
-
-/**
- * bpf_key_put - decrement key reference count if key is valid and free bpf_key
- * @bkey: bpf_key structure
- *
- * Decrement the reference count of the key inside *bkey*, if the pointer
- * is valid, and free *bkey*.
- */
-__bpf_kfunc void bpf_key_put(struct bpf_key *bkey)
-{
- if (bkey->has_ref)
- key_put(bkey->key);
-
- kfree(bkey);
-}
-
-#ifdef CONFIG_SYSTEM_DATA_VERIFICATION
-/**
- * bpf_verify_pkcs7_signature - verify a PKCS#7 signature
- * @data_p: data to verify
- * @sig_p: signature of the data
- * @trusted_keyring: keyring with keys trusted for signature verification
- *
- * Verify the PKCS#7 signature *sig_ptr* against the supplied *data_ptr*
- * with keys in a keyring referenced by *trusted_keyring*.
- *
- * Return: 0 on success, a negative value on error.
- */
-__bpf_kfunc int bpf_verify_pkcs7_signature(struct bpf_dynptr *data_p,
- struct bpf_dynptr *sig_p,
- struct bpf_key *trusted_keyring)
-{
- struct bpf_dynptr_kern *data_ptr = (struct bpf_dynptr_kern *)data_p;
- struct bpf_dynptr_kern *sig_ptr = (struct bpf_dynptr_kern *)sig_p;
- const void *data, *sig;
- u32 data_len, sig_len;
- int ret;
-
- if (trusted_keyring->has_ref) {
- /*
- * Do the permission check deferred in bpf_lookup_user_key().
- * See bpf_lookup_user_key() for more details.
- *
- * A call to key_task_permission() here would be redundant, as
- * it is already done by keyring_search() called by
- * find_asymmetric_key().
- */
- ret = key_validate(trusted_keyring->key);
- if (ret < 0)
- return ret;
- }
-
- data_len = __bpf_dynptr_size(data_ptr);
- data = __bpf_dynptr_data(data_ptr, data_len);
- sig_len = __bpf_dynptr_size(sig_ptr);
- sig = __bpf_dynptr_data(sig_ptr, sig_len);
-
- return verify_pkcs7_signature(data, data_len, sig, sig_len,
- trusted_keyring->key,
- VERIFYING_UNSPECIFIED_SIGNATURE, NULL,
- NULL);
-}
-#endif /* CONFIG_SYSTEM_DATA_VERIFICATION */
-
-__bpf_kfunc_end_defs();
-
-BTF_KFUNCS_START(key_sig_kfunc_set)
-BTF_ID_FLAGS(func, bpf_lookup_user_key, KF_ACQUIRE | KF_RET_NULL | KF_SLEEPABLE)
-BTF_ID_FLAGS(func, bpf_lookup_system_key, KF_ACQUIRE | KF_RET_NULL)
-BTF_ID_FLAGS(func, bpf_key_put, KF_RELEASE)
-#ifdef CONFIG_SYSTEM_DATA_VERIFICATION
-BTF_ID_FLAGS(func, bpf_verify_pkcs7_signature, KF_SLEEPABLE)
-#endif
-BTF_KFUNCS_END(key_sig_kfunc_set)
-
-static const struct btf_kfunc_id_set bpf_key_sig_kfunc_set = {
- .owner = THIS_MODULE,
- .set = &key_sig_kfunc_set,
-};
-
-static int __init bpf_key_sig_kfuncs_init(void)
-{
- return register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING,
- &bpf_key_sig_kfunc_set);
-}
-
-late_initcall(bpf_key_sig_kfuncs_init);
-#endif /* CONFIG_KEYS */
-
static const struct bpf_func_proto *
bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
--
2.43.0
^ permalink raw reply related
* [PATCH v3 08/12] bpf: Implement signature verification for BPF programs
From: KP Singh @ 2025-08-13 20:55 UTC (permalink / raw)
To: bpf, linux-security-module
Cc: bboscaccy, paul, kys, ast, daniel, andrii, KP Singh
In-Reply-To: <20250813205526.2992911-1-kpsingh@kernel.org>
This patch extends the BPF_PROG_LOAD command by adding three new fields
to `union bpf_attr` in the user-space API:
- signature: A pointer to the signature blob.
- signature_size: The size of the signature blob.
- keyring_id: The serial number of a loaded kernel keyring (e.g.,
the user or session keyring) containing the trusted public keys.
When a BPF program is loaded with a signature, the kernel:
1. Retrieves the trusted keyring using the provided `keyring_id`.
2. Verifies the supplied signature against the BPF program's
instruction buffer.
3. If the signature is valid and was generated by a key in the trusted
keyring, the program load proceeds.
4. If no signature is provided, the load proceeds as before, allowing
for backward compatibility. LSMs can chose to restrict unsigned
programs and implement a security policy.
5. If signature verification fails for any reason,
the program is not loaded.
Signed-off-by: KP Singh <kpsingh@kernel.org>
---
crypto/asymmetric_keys/pkcs7_verify.c | 1 +
include/linux/verification.h | 1 +
include/uapi/linux/bpf.h | 10 +++++++
kernel/bpf/helpers.c | 2 +-
kernel/bpf/syscall.c | 42 ++++++++++++++++++++++++++-
tools/include/uapi/linux/bpf.h | 10 +++++++
tools/lib/bpf/bpf.c | 2 +-
7 files changed, 65 insertions(+), 3 deletions(-)
diff --git a/crypto/asymmetric_keys/pkcs7_verify.c b/crypto/asymmetric_keys/pkcs7_verify.c
index f0d4ff3c20a8..6d6475e3a9bf 100644
--- a/crypto/asymmetric_keys/pkcs7_verify.c
+++ b/crypto/asymmetric_keys/pkcs7_verify.c
@@ -429,6 +429,7 @@ int pkcs7_verify(struct pkcs7_message *pkcs7,
/* Authattr presence checked in parser */
break;
case VERIFYING_UNSPECIFIED_SIGNATURE:
+ case VERIFYING_BPF_SIGNATURE:
if (pkcs7->data_type != OID_data) {
pr_warn("Invalid unspecified sig (not pkcs7-data)\n");
return -EKEYREJECTED;
diff --git a/include/linux/verification.h b/include/linux/verification.h
index 4f3022d081c3..dec7f2beabfd 100644
--- a/include/linux/verification.h
+++ b/include/linux/verification.h
@@ -36,6 +36,7 @@ enum key_being_used_for {
VERIFYING_KEY_SIGNATURE,
VERIFYING_KEY_SELF_SIGNATURE,
VERIFYING_UNSPECIFIED_SIGNATURE,
+ VERIFYING_BPF_SIGNATURE,
NR__KEY_BEING_USED_FOR
};
#ifdef CONFIG_SYSTEM_DATA_VERIFICATION
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index fd3b895ebebf..4d8e64f97473 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1607,6 +1607,16 @@ union bpf_attr {
* continuous.
*/
__u32 fd_array_cnt;
+ /* Pointer to a buffer containing the signature of the BPF
+ * program.
+ */
+ __aligned_u64 signature;
+ /* Size of the signature buffer in bytes. */
+ __u32 signature_size;
+ /* ID of the kernel keyring to be used for signature
+ * verification.
+ */
+ __s32 keyring_id;
};
struct { /* anonymous struct used by BPF_OBJ_* commands */
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index a052bbbcbfc5..e883c91b3633 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -3853,7 +3853,7 @@ __bpf_kfunc int bpf_verify_pkcs7_signature(struct bpf_dynptr *data_p,
return verify_pkcs7_signature(data, data_len, sig, sig_len,
trusted_keyring->key,
- VERIFYING_UNSPECIFIED_SIGNATURE, NULL,
+ VERIFYING_BPF_SIGNATURE, NULL,
NULL);
#else
return -EOPNOTSUPP;
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 3d99c443ab7a..ba17ad943c27 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -39,6 +39,7 @@
#include <linux/tracepoint.h>
#include <linux/overflow.h>
#include <linux/cookie.h>
+#include <linux/verification.h>
#include <net/netfilter/nf_bpf_link.h>
#include <net/netkit.h>
@@ -2786,8 +2787,41 @@ static bool is_perfmon_prog_type(enum bpf_prog_type prog_type)
}
}
+static int bpf_prog_verify_signature(struct bpf_prog *prog, union bpf_attr *attr,
+ bool is_kernel)
+{
+ bpfptr_t usig = make_bpfptr(attr->signature, is_kernel);
+ struct bpf_dynptr_kern sig_ptr, insns_ptr;
+ struct bpf_key *key = NULL;
+ void *sig;
+ int err = 0;
+
+ if (system_keyring_id_check(attr->keyring_id) == 0)
+ key = bpf_lookup_system_key(attr->keyring_id);
+ else
+ key = bpf_lookup_user_key(attr->keyring_id, 0);
+
+ sig = kvmemdup_bpfptr(usig, attr->signature_size);
+ if (IS_ERR(sig)) {
+ bpf_key_put(key);
+ return -ENOMEM;
+ }
+
+ bpf_dynptr_init(&sig_ptr, sig, BPF_DYNPTR_TYPE_LOCAL, 0,
+ attr->signature_size);
+ bpf_dynptr_init(&insns_ptr, prog->insnsi, BPF_DYNPTR_TYPE_LOCAL, 0,
+ prog->len * sizeof(struct bpf_insn));
+
+ err = bpf_verify_pkcs7_signature((struct bpf_dynptr *)&insns_ptr,
+ (struct bpf_dynptr *)&sig_ptr, key);
+
+ bpf_key_put(key);
+ kvfree(sig);
+ return err;
+}
+
/* last field in 'union bpf_attr' used by this command */
-#define BPF_PROG_LOAD_LAST_FIELD fd_array_cnt
+#define BPF_PROG_LOAD_LAST_FIELD keyring_id
static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size)
{
@@ -2951,6 +2985,12 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size)
/* eBPF programs must be GPL compatible to use GPL-ed functions */
prog->gpl_compatible = license_is_gpl_compatible(license) ? 1 : 0;
+ if (attr->signature) {
+ err = bpf_prog_verify_signature(prog, attr, uattr.is_kernel);
+ if (err)
+ goto free_prog;
+ }
+
prog->orig_prog = NULL;
prog->jited = 0;
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index fd3b895ebebf..4d8e64f97473 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1607,6 +1607,16 @@ union bpf_attr {
* continuous.
*/
__u32 fd_array_cnt;
+ /* Pointer to a buffer containing the signature of the BPF
+ * program.
+ */
+ __aligned_u64 signature;
+ /* Size of the signature buffer in bytes. */
+ __u32 signature_size;
+ /* ID of the kernel keyring to be used for signature
+ * verification.
+ */
+ __s32 keyring_id;
};
struct { /* anonymous struct used by BPF_OBJ_* commands */
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 6a08a1559237..9c7815ddd829 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -240,7 +240,7 @@ int bpf_prog_load(enum bpf_prog_type prog_type,
const struct bpf_insn *insns, size_t insn_cnt,
struct bpf_prog_load_opts *opts)
{
- const size_t attr_sz = offsetofend(union bpf_attr, fd_array_cnt);
+ const size_t attr_sz = offsetofend(union bpf_attr, keyring_id);
void *finfo = NULL, *linfo = NULL;
const char *func_info, *line_info;
__u32 log_size, log_level, attach_prog_fd, attach_btf_obj_fd;
--
2.43.0
^ permalink raw reply related
* [PATCH v3 09/12] libbpf: Update light skeleton for signing
From: KP Singh @ 2025-08-13 20:55 UTC (permalink / raw)
To: bpf, linux-security-module
Cc: bboscaccy, paul, kys, ast, daniel, andrii, KP Singh
In-Reply-To: <20250813205526.2992911-1-kpsingh@kernel.org>
* The metadata map is created with as an exclusive map (with an
excl_prog_hash) This restricts map access exclusively to the signed
loader program, preventing tampering by other processes.
* The map is then frozen, making it read-only from userspace.
* BPF_OBJ_GET_INFO_BY_ID instructs the kernel to compute the hash of the
metadata map (H') and store it in bpf_map->sha.
* The loader is then loaded with the signature which is then verified by
the kernel.
The sekeleton currently uses the session keyring
(KEY_SPEC_SESSION_KEYRING) by default but this can
be overridden by the user of the skeleton.
loading signed programs prebuilt into the kernel are not currently
supported. These can supported by enabling BPF_OBJ_GET_INFO_BY_ID to be
called from the kernel.
Signed-off-by: KP Singh <kpsingh@kernel.org>
---
tools/lib/bpf/skel_internal.h | 75 +++++++++++++++++++++++++++++++++--
1 file changed, 71 insertions(+), 4 deletions(-)
diff --git a/tools/lib/bpf/skel_internal.h b/tools/lib/bpf/skel_internal.h
index 4d5fa079b5d6..0e8330b85735 100644
--- a/tools/lib/bpf/skel_internal.h
+++ b/tools/lib/bpf/skel_internal.h
@@ -13,10 +13,15 @@
#include <unistd.h>
#include <sys/syscall.h>
#include <sys/mman.h>
+#include <linux/keyctl.h>
#include <stdlib.h>
#include "bpf.h"
#endif
+#ifndef SHA256_DIGEST_LENGTH
+#define SHA256_DIGEST_LENGTH 32
+#endif
+
#ifndef __NR_bpf
# if defined(__mips__) && defined(_ABIO32)
# define __NR_bpf 4355
@@ -64,6 +69,11 @@ struct bpf_load_and_run_opts {
__u32 data_sz;
__u32 insns_sz;
const char *errstr;
+ void *signature;
+ __u32 signature_sz;
+ __s32 keyring_id;
+ void * excl_prog_hash;
+ __u32 excl_prog_hash_sz;
};
long kern_sys_bpf(__u32 cmd, void *attr, __u32 attr_size);
@@ -220,14 +230,19 @@ static inline int skel_map_create(enum bpf_map_type map_type,
const char *map_name,
__u32 key_size,
__u32 value_size,
- __u32 max_entries)
+ __u32 max_entries,
+ const void *excl_prog_hash,
+ __u32 excl_prog_hash_sz)
{
- const size_t attr_sz = offsetofend(union bpf_attr, map_extra);
+ const size_t attr_sz = offsetofend(union bpf_attr, excl_prog_hash);
union bpf_attr attr;
memset(&attr, 0, attr_sz);
attr.map_type = map_type;
+ attr.excl_prog_hash = (unsigned long) excl_prog_hash;
+ attr.excl_prog_hash_size = excl_prog_hash_sz;
+
strncpy(attr.map_name, map_name, sizeof(attr.map_name));
attr.key_size = key_size;
attr.value_size = value_size;
@@ -300,6 +315,34 @@ static inline int skel_link_create(int prog_fd, int target_fd,
return skel_sys_bpf(BPF_LINK_CREATE, &attr, attr_sz);
}
+static inline int skel_obj_get_info_by_fd(int fd)
+{
+ const size_t attr_sz = offsetofend(union bpf_attr, info);
+ __u8 sha[SHA256_DIGEST_LENGTH];
+ struct bpf_map_info info = {};
+ __u32 info_len = sizeof(info);
+ union bpf_attr attr;
+
+ info.hash = (long) &sha;
+ info.hash_size = SHA256_DIGEST_LENGTH;
+
+ memset(&attr, 0, attr_sz);
+ attr.info.bpf_fd = fd;
+ attr.info.info = (long) &info;
+ attr.info.info_len = info_len;
+ return skel_sys_bpf(BPF_OBJ_GET_INFO_BY_FD, &attr, attr_sz);
+}
+
+static inline int skel_map_freeze(int fd)
+{
+ const size_t attr_sz = offsetofend(union bpf_attr, map_fd);
+ union bpf_attr attr;
+
+ memset(&attr, 0, attr_sz);
+ attr.map_fd = fd;
+
+ return skel_sys_bpf(BPF_MAP_FREEZE, &attr, attr_sz);
+}
#ifdef __KERNEL__
#define set_err
#else
@@ -308,12 +351,13 @@ static inline int skel_link_create(int prog_fd, int target_fd,
static inline int bpf_load_and_run(struct bpf_load_and_run_opts *opts)
{
- const size_t prog_load_attr_sz = offsetofend(union bpf_attr, fd_array);
+ const size_t prog_load_attr_sz = offsetofend(union bpf_attr, keyring_id);
const size_t test_run_attr_sz = offsetofend(union bpf_attr, test);
int map_fd = -1, prog_fd = -1, key = 0, err;
union bpf_attr attr;
- err = map_fd = skel_map_create(BPF_MAP_TYPE_ARRAY, "__loader.map", 4, opts->data_sz, 1);
+ err = map_fd = skel_map_create(BPF_MAP_TYPE_ARRAY, "__loader.map", 4, opts->data_sz, 1,
+ opts->excl_prog_hash, opts->excl_prog_hash_sz);
if (map_fd < 0) {
opts->errstr = "failed to create loader map";
set_err;
@@ -327,11 +371,34 @@ static inline int bpf_load_and_run(struct bpf_load_and_run_opts *opts)
goto out;
}
+#ifndef __KERNEL__
+ err = skel_map_freeze(map_fd);
+ if (err < 0) {
+ opts->errstr = "failed to freeze map";
+ set_err;
+ goto out;
+ }
+ err = skel_obj_get_info_by_fd(map_fd);
+ if (err < 0) {
+ opts->errstr = "failed to fetch obj info";
+ set_err;
+ goto out;
+ }
+#endif
+
memset(&attr, 0, prog_load_attr_sz);
attr.prog_type = BPF_PROG_TYPE_SYSCALL;
attr.insns = (long) opts->insns;
attr.insn_cnt = opts->insns_sz / sizeof(struct bpf_insn);
attr.license = (long) "Dual BSD/GPL";
+#ifndef __KERNEL__
+ attr.signature = (long) opts->signature;
+ attr.signature_size = opts->signature_sz;
+#else
+ if (opts->signature || opts->signature_sz)
+ pr_warn("signatures are not supported from bpf_preload\n");
+#endif
+ attr.keyring_id = opts->keyring_id;
memcpy(attr.prog_name, "__loader.prog", sizeof("__loader.prog"));
attr.fd_array = (long) &map_fd;
attr.log_level = opts->ctx->log_level;
--
2.43.0
^ permalink raw reply related
* [PATCH v3 10/12] libbpf: Embed and verify the metadata hash in the loader
From: KP Singh @ 2025-08-13 20:55 UTC (permalink / raw)
To: bpf, linux-security-module
Cc: bboscaccy, paul, kys, ast, daniel, andrii, KP Singh
In-Reply-To: <20250813205526.2992911-1-kpsingh@kernel.org>
To fulfill the BPF signing contract, represented as Sig(I_loader ||
H_meta), the generated trusted loader program must verify the integrity
of the metadata. This signature cryptographically binds the loader's
instructions (I_loader) to a hash of the metadata (H_meta).
The verification process is embedded directly into the loader program.
Upon execution, the loader loads the runtime hash from struct bpf_map
i.e. BPF_PSEUDO_MAP_IDX and compares this runtime hash against an
expected hash value that has been hardcoded directly by
bpf_obj__gen_loader.
The load from bpf_map can be improved by calling
BPF_OBJ_GET_INFO_BY_FD from the kernel context after BPF_OBJ_GET_INFO_BY_FD
has been updated for being called from the kernel context.
The following instructions are generated:
ld_imm64 r1, const_ptr_to_map // insn[0].src_reg == BPF_PSEUDO_MAP_IDX
r2 = *(u64 *)(r1 + 0);
ld_imm64 r3, sha256_of_map_part1 // constant precomputed by
bpftool (part of H_meta)
if r2 != r3 goto out;
r2 = *(u64 *)(r1 + 8);
ld_imm64 r3, sha256_of_map_part2 // (part of H_meta)
if r2 != r3 goto out;
r2 = *(u64 *)(r1 + 16);
ld_imm64 r3, sha256_of_map_part3 // (part of H_meta)
if r2 != r3 goto out;
r2 = *(u64 *)(r1 + 24);
ld_imm64 r3, sha256_of_map_part4 // (part of H_meta)
if r2 != r3 goto out;
...
Signed-off-by: KP Singh <kpsingh@kernel.org>
---
tools/lib/bpf/bpf_gen_internal.h | 2 ++
tools/lib/bpf/gen_loader.c | 55 ++++++++++++++++++++++++++++++++
tools/lib/bpf/libbpf.h | 3 +-
3 files changed, 59 insertions(+), 1 deletion(-)
diff --git a/tools/lib/bpf/bpf_gen_internal.h b/tools/lib/bpf/bpf_gen_internal.h
index 6ff963a491d9..49af4260b8e6 100644
--- a/tools/lib/bpf/bpf_gen_internal.h
+++ b/tools/lib/bpf/bpf_gen_internal.h
@@ -4,6 +4,7 @@
#define __BPF_GEN_INTERNAL_H
#include "bpf.h"
+#include "libbpf_internal.h"
struct ksym_relo_desc {
const char *name;
@@ -50,6 +51,7 @@ struct bpf_gen {
__u32 nr_ksyms;
int fd_array;
int nr_fd_array;
+ int hash_insn_offset[SHA256_DWORD_SIZE];
};
void bpf_gen__init(struct bpf_gen *gen, int log_level, int nr_progs, int nr_maps);
diff --git a/tools/lib/bpf/gen_loader.c b/tools/lib/bpf/gen_loader.c
index 113ae4abd345..8eba7c1514ef 100644
--- a/tools/lib/bpf/gen_loader.c
+++ b/tools/lib/bpf/gen_loader.c
@@ -110,6 +110,7 @@ static void emit2(struct bpf_gen *gen, struct bpf_insn insn1, struct bpf_insn in
static int add_data(struct bpf_gen *gen, const void *data, __u32 size);
static void emit_sys_close_blob(struct bpf_gen *gen, int blob_off);
+static void bpf_gen__signature_match(struct bpf_gen *gen);
void bpf_gen__init(struct bpf_gen *gen, int log_level, int nr_progs, int nr_maps)
{
@@ -152,6 +153,8 @@ void bpf_gen__init(struct bpf_gen *gen, int log_level, int nr_progs, int nr_maps
/* R7 contains the error code from sys_bpf. Copy it into R0 and exit. */
emit(gen, BPF_MOV64_REG(BPF_REG_0, BPF_REG_7));
emit(gen, BPF_EXIT_INSN());
+ if (OPTS_GET(gen->opts, gen_hash, false))
+ bpf_gen__signature_match(gen);
}
static int add_data(struct bpf_gen *gen, const void *data, __u32 size)
@@ -368,6 +371,8 @@ static void emit_sys_close_blob(struct bpf_gen *gen, int blob_off)
__emit_sys_close(gen);
}
+static int compute_sha_udpate_offsets(struct bpf_gen *gen);
+
int bpf_gen__finish(struct bpf_gen *gen, int nr_progs, int nr_maps)
{
int i;
@@ -394,6 +399,12 @@ int bpf_gen__finish(struct bpf_gen *gen, int nr_progs, int nr_maps)
blob_fd_array_off(gen, i));
emit(gen, BPF_MOV64_IMM(BPF_REG_0, 0));
emit(gen, BPF_EXIT_INSN());
+ if (OPTS_GET(gen->opts, gen_hash, false)) {
+ gen->error = compute_sha_udpate_offsets(gen);
+ if (gen->error)
+ return gen->error;
+ }
+
pr_debug("gen: finish %s\n", errstr(gen->error));
if (!gen->error) {
struct gen_loader_opts *opts = gen->opts;
@@ -446,6 +457,27 @@ void bpf_gen__free(struct bpf_gen *gen)
_val; \
})
+static int compute_sha_udpate_offsets(struct bpf_gen *gen)
+{
+ __u64 sha[SHA256_DWORD_SIZE];
+ __u64 sha_dw;
+ int i, err;
+
+ err = libbpf_sha256(gen->data_start, gen->data_cur - gen->data_start, sha, SHA256_DIGEST_LENGTH);
+ if (err < 0) {
+ pr_warn("sha256 computation of the metadata failed");
+ return err;
+ }
+ for (i = 0; i < SHA256_DWORD_SIZE; i++) {
+ struct bpf_insn *insn =
+ (struct bpf_insn *)(gen->insn_start + gen->hash_insn_offset[i]);
+ sha_dw = tgt_endian(sha[i]);
+ insn[0].imm = (__u32)sha_dw;
+ insn[1].imm = sha_dw >> 32;
+ }
+ return 0;
+}
+
void bpf_gen__load_btf(struct bpf_gen *gen, const void *btf_raw_data,
__u32 btf_raw_size)
{
@@ -557,6 +589,29 @@ void bpf_gen__map_create(struct bpf_gen *gen,
emit_sys_close_stack(gen, stack_off(inner_map_fd));
}
+static void bpf_gen__signature_match(struct bpf_gen *gen)
+{
+ __s64 off;
+ int i;
+
+ for (i = 0; i < SHA256_DWORD_SIZE; i++) {
+ emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX,
+ 0, 0, 0, 0));
+ emit(gen, BPF_LDX_MEM(BPF_DW, BPF_REG_2, BPF_REG_1, i * sizeof(__u64)));
+ gen->hash_insn_offset[i] = gen->insn_cur - gen->insn_start;
+ emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_3, 0, 0, 0, 0, 0));
+
+ off = -(gen->insn_cur - gen->insn_start - gen->cleanup_label) / 8 - 1;
+ if (is_simm16(off)) {
+ emit(gen, BPF_MOV64_IMM(BPF_REG_7, -EINVAL));
+ emit(gen, BPF_JMP_REG(BPF_JNE, BPF_REG_2, BPF_REG_3, off));
+ } else {
+ gen->error = -ERANGE;
+ emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0, -1));
+ }
+ }
+}
+
void bpf_gen__record_attach_target(struct bpf_gen *gen, const char *attach_name,
enum bpf_attach_type type)
{
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index ddaf58c8a298..826e0395427d 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -1828,9 +1828,10 @@ struct gen_loader_opts {
const char *insns;
__u32 data_sz;
__u32 insns_sz;
+ bool gen_hash;
};
-#define gen_loader_opts__last_field insns_sz
+#define gen_loader_opts__last_field gen_hash
LIBBPF_API int bpf_object__gen_loader(struct bpf_object *obj,
struct gen_loader_opts *opts);
--
2.43.0
^ permalink raw reply related
* [PATCH v3 11/12] bpftool: Add support for signing BPF programs
From: KP Singh @ 2025-08-13 20:55 UTC (permalink / raw)
To: bpf, linux-security-module
Cc: bboscaccy, paul, kys, ast, daniel, andrii, KP Singh
In-Reply-To: <20250813205526.2992911-1-kpsingh@kernel.org>
Two modes of operation being added:
Add two modes of operation:
* For prog load, allow signing a program immediately before loading. This
is essential for command-line testing and administration.
bpftool prog load -S -k <private_key> -i <identity_cert> fentry_test.bpf.o
* For gen skeleton, embed a pre-generated signature into the C skeleton
file. This supports the use of signed programs in compiled applications.
bpftool gen skeleton -S -k <private_key> -i <identity_cert> fentry_test.bpf.o
Generation of the loader program and its metadata map is implemented in
libbpf (bpf_obj__gen_loader). bpftool generates a skeleton that loads
the program and automates the required steps: freezing the map, creating
an exclusive map, loading, and running. Users can use standard libbpf
APIs directly or integrate loader program generation into their own
toolchains.
Signed-off-by: KP Singh <kpsingh@kernel.org>
---
.../bpf/bpftool/Documentation/bpftool-gen.rst | 16 +-
.../bpftool/Documentation/bpftool-prog.rst | 18 +-
tools/bpf/bpftool/Makefile | 6 +-
tools/bpf/bpftool/cgroup.c | 4 +
tools/bpf/bpftool/gen.c | 60 ++++-
tools/bpf/bpftool/main.c | 26 ++-
tools/bpf/bpftool/main.h | 11 +
tools/bpf/bpftool/prog.c | 27 ++-
tools/bpf/bpftool/sign.c | 212 ++++++++++++++++++
9 files changed, 367 insertions(+), 13 deletions(-)
create mode 100644 tools/bpf/bpftool/sign.c
diff --git a/tools/bpf/bpftool/Documentation/bpftool-gen.rst b/tools/bpf/bpftool/Documentation/bpftool-gen.rst
index ca860fd97d8d..cef469d758ed 100644
--- a/tools/bpf/bpftool/Documentation/bpftool-gen.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool-gen.rst
@@ -16,7 +16,8 @@ SYNOPSIS
**bpftool** [*OPTIONS*] **gen** *COMMAND*
-*OPTIONS* := { |COMMON_OPTIONS| | { **-L** | **--use-loader** } }
+*OPTIONS* := { |COMMON_OPTIONS| [ { **-L** | **--use-loader** } ]
+[ { { **-S** | **--sign** } **-k** <private_key.pem> **-i** <certificate.x509> } ] }}
*COMMAND* := { **object** | **skeleton** | **help** }
@@ -186,6 +187,19 @@ OPTIONS
skeleton). A light skeleton contains a loader eBPF program. It does not use
the majority of the libbpf infrastructure, and does not need libelf.
+-S, --sign
+ For skeletons, generate a signed skeleton. This option must be used with
+ **-k** and **-i**. Using this flag implicitly enables **--use-loader**.
+ See the "Signed Skeletons" section in the description of the
+ **gen skeleton** command for more details.
+
+-k <private_key.pem>
+ Path to the private key file in PEM format, required for signing.
+
+-i <certificate.x509>
+ Path to the X.509 certificate file in PEM or DER format, required for
+ signing.
+
EXAMPLES
========
**$ cat example1.bpf.c**
diff --git a/tools/bpf/bpftool/Documentation/bpftool-prog.rst b/tools/bpf/bpftool/Documentation/bpftool-prog.rst
index f69fd92df8d8..55b812761df2 100644
--- a/tools/bpf/bpftool/Documentation/bpftool-prog.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool-prog.rst
@@ -16,9 +16,9 @@ SYNOPSIS
**bpftool** [*OPTIONS*] **prog** *COMMAND*
-*OPTIONS* := { |COMMON_OPTIONS| |
-{ **-f** | **--bpffs** } | { **-m** | **--mapcompat** } | { **-n** | **--nomount** } |
-{ **-L** | **--use-loader** } }
+*OPTIONS* := { |COMMON_OPTIONS| [ { **-f** | **--bpffs** } ] [ { **-m** | **--mapcompat** } ]
+[ { **-n** | **--nomount** } ] [ { **-L** | **--use-loader** } ]
+[ { { **-S** | **--sign** } **-k** <private_key.pem> **-i** <certificate.x509> } ] }
*COMMANDS* :=
{ **show** | **list** | **dump xlated** | **dump jited** | **pin** | **load** |
@@ -248,6 +248,18 @@ OPTIONS
creating the maps, and loading the programs (see **bpftool prog tracelog**
as a way to dump those messages).
+-S, --sign
+ Enable signing of the BPF program before loading. This option must be
+ used with **-k** and **-i**. Using this flag implicitly enables
+ **--use-loader**.
+
+-k <private_key.pem>
+ Path to the private key file in PEM format, required when signing.
+
+-i <certificate.x509>
+ Path to the X.509 certificate file in PEM or DER format, required when
+ signing.
+
EXAMPLES
========
**# bpftool prog show**
diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile
index 9e9a5f006cd2..586d1b2595d1 100644
--- a/tools/bpf/bpftool/Makefile
+++ b/tools/bpf/bpftool/Makefile
@@ -130,8 +130,8 @@ include $(FEATURES_DUMP)
endif
endif
-LIBS = $(LIBBPF) -lelf -lz
-LIBS_BOOTSTRAP = $(LIBBPF_BOOTSTRAP) -lelf -lz
+LIBS = $(LIBBPF) -lelf -lz -lcrypto
+LIBS_BOOTSTRAP = $(LIBBPF_BOOTSTRAP) -lelf -lz -lcrypto
ifeq ($(feature-libelf-zstd),1)
LIBS += -lzstd
@@ -194,7 +194,7 @@ endif
BPFTOOL_BOOTSTRAP := $(BOOTSTRAP_OUTPUT)bpftool
-BOOTSTRAP_OBJS = $(addprefix $(BOOTSTRAP_OUTPUT),main.o common.o json_writer.o gen.o btf.o)
+BOOTSTRAP_OBJS = $(addprefix $(BOOTSTRAP_OUTPUT),main.o common.o json_writer.o gen.o btf.o sign.o)
$(BOOTSTRAP_OBJS): $(LIBBPF_BOOTSTRAP)
OBJS = $(patsubst %.c,$(OUTPUT)%.o,$(SRCS)) $(OUTPUT)disasm.o
diff --git a/tools/bpf/bpftool/cgroup.c b/tools/bpf/bpftool/cgroup.c
index 944ebe21a216..ec356deb27c9 100644
--- a/tools/bpf/bpftool/cgroup.c
+++ b/tools/bpf/bpftool/cgroup.c
@@ -2,6 +2,10 @@
// Copyright (C) 2017 Facebook
// Author: Roman Gushchin <guro@fb.com>
+#undef GCC_VERSION
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
#define _XOPEN_SOURCE 500
#include <errno.h>
#include <fcntl.h>
diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
index 67a60114368f..427468c9e9c2 100644
--- a/tools/bpf/bpftool/gen.c
+++ b/tools/bpf/bpftool/gen.c
@@ -688,10 +688,17 @@ static void codegen_destroy(struct bpf_object *obj, const char *obj_name)
static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *header_guard)
{
DECLARE_LIBBPF_OPTS(gen_loader_opts, opts);
+ struct bpf_load_and_run_opts sopts = {};
+ char sig_buf[MAX_SIG_SIZE];
+ __u8 prog_sha[SHA256_DIGEST_LENGTH];
struct bpf_map *map;
+
char ident[256];
int err = 0;
+ if (sign_progs)
+ opts.gen_hash = true;
+
err = bpf_object__gen_loader(obj, &opts);
if (err)
return err;
@@ -701,6 +708,7 @@ static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *h
p_err("failed to load object file");
goto out;
}
+
/* If there was no error during load then gen_loader_opts
* are populated with the loader program.
*/
@@ -780,8 +788,51 @@ static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *h
print_hex(opts.insns, opts.insns_sz);
codegen("\
\n\
- \"; \n\
- \n\
+ \";\n");
+
+ if (sign_progs) {
+ sopts.insns = opts.insns;
+ sopts.insns_sz = opts.insns_sz;
+ sopts.excl_prog_hash = prog_sha;
+ sopts.excl_prog_hash_sz = sizeof(prog_sha);
+ sopts.signature = sig_buf;
+ sopts.signature_sz = MAX_SIG_SIZE;
+ sopts.keyring_id = KEY_SPEC_SESSION_KEYRING;
+
+ err = bpftool_prog_sign(&sopts);
+ if (err < 0)
+ return err;
+
+ codegen("\
+ \n\
+ static const char opts_sig[] __attribute__((__aligned__(8))) = \"\\\n\
+ ");
+ print_hex((const void *)sig_buf, sopts.signature_sz);
+ codegen("\
+ \n\
+ \";\n");
+
+ codegen("\
+ \n\
+ static const char opts_excl_hash[] __attribute__((__aligned__(8))) = \"\\\n\
+ ");
+ print_hex((const void *)prog_sha, sizeof(prog_sha));
+ codegen("\
+ \n\
+ \";\n");
+
+ codegen("\
+ \n\
+ opts.signature = (void *)opts_sig; \n\
+ opts.signature_sz = sizeof(opts_sig) - 1; \n\
+ opts.excl_prog_hash = (void *)opts_excl_hash; \n\
+ opts.excl_prog_hash_sz = sizeof(opts_excl_hash) - 1; \n\
+ opts.keyring_id = KEY_SPEC_SESSION_KEYRING; \n\
+ ");
+ }
+
+ codegen("\
+ \n\
opts.ctx = (struct bpf_loader_ctx *)skel; \n\
opts.data_sz = sizeof(opts_data) - 1; \n\
opts.data = (void *)opts_data; \n\
@@ -1240,7 +1291,7 @@ static int do_skeleton(int argc, char **argv)
err = -errno;
libbpf_strerror(err, err_buf, sizeof(err_buf));
p_err("failed to open BPF object file: %s", err_buf);
- goto out;
+ goto out_obj;
}
bpf_object__for_each_map(map, obj) {
@@ -1552,6 +1603,7 @@ static int do_skeleton(int argc, char **argv)
err = 0;
out:
bpf_object__close(obj);
+out_obj:
if (obj_data)
munmap(obj_data, mmap_sz);
close(fd);
@@ -1930,7 +1982,7 @@ static int do_help(int argc, char **argv)
" %1$s %2$s help\n"
"\n"
" " HELP_SPEC_OPTIONS " |\n"
- " {-L|--use-loader} }\n"
+ " {-L|--use-loader} | [ {-S|--sign } {-k} <private_key.pem> {-i} <certificate.x509> ]}\n"
"",
bin_name, "gen");
diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c
index 0f1183b2ed0a..c78eb80b9c94 100644
--- a/tools/bpf/bpftool/main.c
+++ b/tools/bpf/bpftool/main.c
@@ -33,6 +33,9 @@ bool relaxed_maps;
bool use_loader;
struct btf *base_btf;
struct hashmap *refs_table;
+bool sign_progs;
+const char *private_key_path;
+const char *cert_path;
static void __noreturn clean_and_exit(int i)
{
@@ -448,6 +451,7 @@ int main(int argc, char **argv)
{ "nomount", no_argument, NULL, 'n' },
{ "debug", no_argument, NULL, 'd' },
{ "use-loader", no_argument, NULL, 'L' },
+ { "sign", no_argument, NULL, 'S' },
{ "base-btf", required_argument, NULL, 'B' },
{ 0 }
};
@@ -474,7 +478,7 @@ int main(int argc, char **argv)
bin_name = "bpftool";
opterr = 0;
- while ((opt = getopt_long(argc, argv, "VhpjfLmndB:l",
+ while ((opt = getopt_long(argc, argv, "VhpjfLmndSi:k:B:l",
options, NULL)) >= 0) {
switch (opt) {
case 'V':
@@ -520,6 +524,16 @@ int main(int argc, char **argv)
case 'L':
use_loader = true;
break;
+ case 'S':
+ sign_progs = true;
+ use_loader = true;
+ break;
+ case 'k':
+ private_key_path = optarg;
+ break;
+ case 'i':
+ cert_path = optarg;
+ break;
default:
p_err("unrecognized option '%s'", argv[optind - 1]);
if (json_output)
@@ -534,6 +548,16 @@ int main(int argc, char **argv)
if (argc < 0)
usage();
+ if (sign_progs && (private_key_path == NULL || cert_path == NULL)) {
+ p_err("-i <identity_x509_cert> and -k <private> key must be supplied with -S for signing");
+ return -EINVAL;
+ }
+
+ if (!sign_progs && (private_key_path != NULL || cert_path != NULL)) {
+ p_err("-i <identity_x509_cert> and -k <private> also need --sign to be used for sign programs");
+ return -EINVAL;
+ }
+
if (version_requested)
ret = do_version(argc, argv);
else
diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
index a2bb0714b3d6..f7f5b39b66c8 100644
--- a/tools/bpf/bpftool/main.h
+++ b/tools/bpf/bpftool/main.h
@@ -6,9 +6,14 @@
/* BFD and kernel.h both define GCC_VERSION, differently */
#undef GCC_VERSION
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
#include <stdbool.h>
#include <stdio.h>
+#include <errno.h>
#include <stdlib.h>
+#include <bpf/skel_internal.h>
#include <linux/bpf.h>
#include <linux/compiler.h>
#include <linux/kernel.h>
@@ -52,6 +57,7 @@ static inline void *u64_to_ptr(__u64 ptr)
})
#define ERR_MAX_LEN 1024
+#define MAX_SIG_SIZE 4096
#define BPF_TAG_FMT "%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx"
@@ -85,6 +91,9 @@ extern bool relaxed_maps;
extern bool use_loader;
extern struct btf *base_btf;
extern struct hashmap *refs_table;
+extern bool sign_progs;
+extern const char *private_key_path;
+extern const char *cert_path;
void __printf(1, 2) p_err(const char *fmt, ...);
void __printf(1, 2) p_info(const char *fmt, ...);
@@ -275,4 +284,6 @@ int pathname_concat(char *buf, int buf_sz, const char *path,
/* print netfilter bpf_link info */
void netfilter_dump_plain(const struct bpf_link_info *info);
void netfilter_dump_json(const struct bpf_link_info *info, json_writer_t *wtr);
+int bpftool_prog_sign(struct bpf_load_and_run_opts *opts);
+__u32 register_session_key(const char *key_der_path);
#endif
diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index 9722d841abc0..82b8da084504 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -23,6 +23,7 @@
#include <linux/err.h>
#include <linux/perf_event.h>
#include <linux/sizes.h>
+#include <linux/keyctl.h>
#include <bpf/bpf.h>
#include <bpf/btf.h>
@@ -1930,6 +1931,8 @@ static int try_loader(struct gen_loader_opts *gen)
{
struct bpf_load_and_run_opts opts = {};
struct bpf_loader_ctx *ctx;
+ char sig_buf[MAX_SIG_SIZE];
+ __u8 prog_sha[SHA256_DIGEST_LENGTH];
int ctx_sz = sizeof(*ctx) + 64 * max(sizeof(struct bpf_map_desc),
sizeof(struct bpf_prog_desc));
int log_buf_sz = (1u << 24) - 1;
@@ -1953,6 +1956,24 @@ static int try_loader(struct gen_loader_opts *gen)
opts.insns = gen->insns;
opts.insns_sz = gen->insns_sz;
fds_before = count_open_fds();
+
+ if (sign_progs) {
+ opts.excl_prog_hash = prog_sha;
+ opts.excl_prog_hash_sz = sizeof(prog_sha);
+ opts.signature = sig_buf;
+ opts.signature_sz = MAX_SIG_SIZE;
+ opts.keyring_id = KEY_SPEC_SESSION_KEYRING;
+
+ err = bpftool_prog_sign(&opts);
+ if (err < 0)
+ return err;
+
+ err = register_session_key(cert_path);
+ if (err < 0) {
+ p_err("failed to add session key");
+ goto out;
+ }
+ }
err = bpf_load_and_run(&opts);
fd_delta = count_open_fds() - fds_before;
if (err < 0 || verifier_logs) {
@@ -1961,6 +1982,7 @@ static int try_loader(struct gen_loader_opts *gen)
fprintf(stderr, "loader prog leaked %d FDs\n",
fd_delta);
}
+out:
free(log_buf);
return err;
}
@@ -1988,6 +2010,9 @@ static int do_loader(int argc, char **argv)
goto err_close_obj;
}
+ if (sign_progs)
+ gen.gen_hash = true;
+
err = bpf_object__gen_loader(obj, &gen);
if (err)
goto err_close_obj;
@@ -2562,7 +2587,7 @@ static int do_help(int argc, char **argv)
" METRIC := { cycles | instructions | l1d_loads | llc_misses | itlb_misses | dtlb_misses }\n"
" " HELP_SPEC_OPTIONS " |\n"
" {-f|--bpffs} | {-m|--mapcompat} | {-n|--nomount} |\n"
- " {-L|--use-loader} }\n"
+ " {-L|--use-loader} | [ {-S|--sign } {-k} <private_key.pem> {-i} <certificate.x509> ] \n"
"",
bin_name, argv[-2]);
diff --git a/tools/bpf/bpftool/sign.c b/tools/bpf/bpftool/sign.c
new file mode 100644
index 000000000000..b29d825bb1d4
--- /dev/null
+++ b/tools/bpf/bpftool/sign.c
@@ -0,0 +1,212 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+/*
+ * Copyright (C) 2025 Google LLC.
+ */
+
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <string.h>
+#include <string.h>
+#include <getopt.h>
+#include <err.h>
+#include <openssl/opensslv.h>
+#include <openssl/bio.h>
+#include <openssl/evp.h>
+#include <openssl/pem.h>
+#include <openssl/err.h>
+#include <openssl/cms.h>
+#include <linux/keyctl.h>
+#include <errno.h>
+
+#include <bpf/skel_internal.h>
+
+#include "main.h"
+
+#define OPEN_SSL_ERR_BUF_LEN 256
+
+static void display_openssl_errors(int l)
+{
+ char buf[OPEN_SSL_ERR_BUF_LEN];
+ const char *file;
+ const char *data;
+ unsigned long e;
+ int flags;
+ int line;
+
+ while ((e = ERR_get_error_all(&file, &line, NULL, &data, &flags))) {
+ ERR_error_string_n(e, buf, sizeof(buf));
+ if (data && (flags & ERR_TXT_STRING)) {
+ p_err("OpenSSL %s: %s:%d: %s", buf, file, line, data);
+ } else {
+ p_err("OpenSSL %s: %s:%d", buf, file, line);
+ }
+ }
+}
+
+#define DISPLAY_OSSL_ERR(cond) \
+ do { \
+ bool __cond = (cond); \
+ if (__cond && ERR_peek_error()) \
+ display_openssl_errors(__LINE__);\
+ } while (0)
+
+static EVP_PKEY *read_private_key(const char *pkey_path)
+{
+ EVP_PKEY *private_key = NULL;
+ BIO *b;
+
+ b = BIO_new_file(pkey_path, "rb");
+ private_key = PEM_read_bio_PrivateKey(b, NULL, NULL, NULL);
+ BIO_free(b);
+ DISPLAY_OSSL_ERR(!private_key);
+ return private_key;
+}
+
+static X509 *read_x509(const char *x509_name)
+{
+ unsigned char buf[2];
+ X509 *x509 = NULL;
+ BIO *b;
+ int n;
+
+ b = BIO_new_file(x509_name, "rb");
+ if (!b)
+ goto cleanup;
+
+ /* Look at the first two bytes of the file to determine the encoding */
+ n = BIO_read(b, buf, 2);
+ if (n != 2)
+ goto cleanup;
+
+ if (BIO_reset(b) != 0)
+ goto cleanup;
+
+ if (buf[0] == 0x30 && buf[1] >= 0x81 && buf[1] <= 0x84)
+ /* Assume raw DER encoded X.509 */
+ x509 = d2i_X509_bio(b, NULL);
+ else
+ /* Assume PEM encoded X.509 */
+ x509 = PEM_read_bio_X509(b, NULL, NULL, NULL);
+
+cleanup:
+ BIO_free(b);
+ DISPLAY_OSSL_ERR(!x509);
+ return x509;
+}
+
+__u32 register_session_key(const char *key_der_path)
+{
+ unsigned char *der_buf = NULL;
+ X509 *x509 = NULL;
+ int key_id = -1;
+ int der_len;
+
+ if (!key_der_path)
+ return key_id;
+ x509 = read_x509(key_der_path);
+ if (!x509)
+ goto cleanup;
+ der_len = i2d_X509(x509, &der_buf);
+ if (der_len < 0)
+ goto cleanup;
+ key_id = syscall(__NR_add_key, "asymmetric", key_der_path, der_buf,
+ (size_t)der_len, KEY_SPEC_SESSION_KEYRING);
+cleanup:
+ X509_free(x509);
+ OPENSSL_free(der_buf);
+ DISPLAY_OSSL_ERR(key_id == -1);
+ return key_id;
+}
+
+int bpftool_prog_sign(struct bpf_load_and_run_opts *opts)
+{
+ BIO *bd_in = NULL, *bd_out = NULL;
+ EVP_PKEY *private_key = NULL;
+ CMS_ContentInfo *cms = NULL;
+ long actual_sig_len = 0;
+ X509 *x509 = NULL;
+ int err = 0;
+
+ bd_in = BIO_new_mem_buf(opts->insns, opts->insns_sz);
+ if (!bd_in) {
+ err = -ENOMEM;
+ goto cleanup;
+ }
+
+ private_key = read_private_key(private_key_path);
+ if (!private_key) {
+ err = -EINVAL;
+ goto cleanup;
+ }
+
+ x509 = read_x509(cert_path);
+ if (!x509) {
+ err = -EINVAL;
+ goto cleanup;
+ }
+
+ cms = CMS_sign(NULL, NULL, NULL, NULL,
+ CMS_NOCERTS | CMS_PARTIAL | CMS_BINARY | CMS_DETACHED |
+ CMS_STREAM);
+ if (!cms) {
+ err = -EINVAL;
+ goto cleanup;
+ }
+
+ if (!CMS_add1_signer(cms, x509, private_key, EVP_sha256(),
+ CMS_NOCERTS | CMS_BINARY | CMS_NOSMIMECAP |
+ CMS_USE_KEYID | CMS_NOATTR)) {
+ err = -EINVAL;
+ goto cleanup;
+ }
+
+ if (CMS_final(cms, bd_in, NULL, CMS_NOCERTS | CMS_BINARY) != 1) {
+ err = -EIO;
+ goto cleanup;
+ }
+
+ EVP_Digest(opts->insns, opts->insns_sz, opts->excl_prog_hash,
+ &opts->excl_prog_hash_sz, EVP_sha256(), NULL);
+
+ bd_out = BIO_new(BIO_s_mem());
+ if (!bd_out) {
+ err = -ENOMEM;
+ goto cleanup;
+ }
+
+ if (!i2d_CMS_bio_stream(bd_out, cms, NULL, 0)) {
+ err = -EIO;
+ goto cleanup;
+ }
+
+ actual_sig_len = BIO_get_mem_data(bd_out, NULL);
+ if (actual_sig_len <= 0) {
+ err = -EIO;
+ goto cleanup;
+ }
+
+ if ((size_t)actual_sig_len > opts->signature_sz) {
+ err = -ENOSPC;
+ goto cleanup;
+ }
+
+ if (BIO_read(bd_out, opts->signature, actual_sig_len) != actual_sig_len) {
+ err = -EIO;
+ goto cleanup;
+ }
+
+ opts->signature_sz = actual_sig_len;
+cleanup:
+ BIO_free(bd_out);
+ CMS_ContentInfo_free(cms);
+ X509_free(x509);
+ EVP_PKEY_free(private_key);
+ BIO_free(bd_in);
+ DISPLAY_OSSL_ERR(err < 0);
+ return err;
+}
--
2.43.0
^ permalink raw reply related
* [PATCH v3 12/12] selftests/bpf: Enable signature verification for some lskel tests
From: KP Singh @ 2025-08-13 20:55 UTC (permalink / raw)
To: bpf, linux-security-module
Cc: bboscaccy, paul, kys, ast, daniel, andrii, KP Singh
In-Reply-To: <20250813205526.2992911-1-kpsingh@kernel.org>
The test harness uses the verify_sig_setup.sh to generate the required
key material for program signing.
Generate key material for signing LSKEL some lskel programs and use
xxd to convert the verification certificate into a C header file.
Finally, update the main test runner to load this
certificate into the session keyring via the add_key() syscall before
executing any tests.
Signed-off-by: KP Singh <kpsingh@kernel.org>
---
tools/testing/selftests/bpf/.gitignore | 1 +
tools/testing/selftests/bpf/Makefile | 35 ++++++++++++++++---
tools/testing/selftests/bpf/test_progs.c | 13 +++++++
.../testing/selftests/bpf/verify_sig_setup.sh | 13 +++++--
4 files changed, 56 insertions(+), 6 deletions(-)
diff --git a/tools/testing/selftests/bpf/.gitignore b/tools/testing/selftests/bpf/.gitignore
index 3d8378972d26..be1ee7ba7ce0 100644
--- a/tools/testing/selftests/bpf/.gitignore
+++ b/tools/testing/selftests/bpf/.gitignore
@@ -44,3 +44,4 @@ xdp_redirect_multi
xdp_synproxy
xdp_hw_metadata
xdp_features
+verification_cert.h
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 4863106034df..e473e2d780fb 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -496,15 +496,16 @@ LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h \
test_subskeleton.skel.h test_subskeleton_lib.skel.h \
test_usdt.skel.h
-LSKELS := fentry_test.c fexit_test.c fexit_sleep.c atomics.c \
- trace_printk.c trace_vprintk.c map_ptr_kern.c \
+LSKELS := fexit_sleep.c trace_printk.c trace_vprintk.c map_ptr_kern.c \
core_kern.c core_kern_overflow.c test_ringbuf.c \
test_ringbuf_n.c test_ringbuf_map_key.c test_ringbuf_write.c
+LSKELS_SIGNED := fentry_test.c fexit_test.c atomics.c
+
# Generate both light skeleton and libbpf skeleton for these
LSKELS_EXTRA := test_ksyms_module.c test_ksyms_weak.c kfunc_call_test.c \
kfunc_call_test_subprog.c
-SKEL_BLACKLIST += $$(LSKELS)
+SKEL_BLACKLIST += $$(LSKELS) $$(LSKELS_SIGNED)
test_static_linked.skel.h-deps := test_static_linked1.bpf.o test_static_linked2.bpf.o
linked_funcs.skel.h-deps := linked_funcs1.bpf.o linked_funcs2.bpf.o
@@ -535,6 +536,7 @@ HEADERS_FOR_BPF_OBJS := $(wildcard $(BPFDIR)/*.bpf.h) \
# $2 - test runner extra "flavor" (e.g., no_alu32, cpuv4, bpf_gcc, etc)
define DEFINE_TEST_RUNNER
+LSKEL_SIGN := -S -k $(PRIVATE_KEY) -i $(VERIFICATION_CERT)
TRUNNER_OUTPUT := $(OUTPUT)$(if $2,/)$2
TRUNNER_BINARY := $1$(if $2,-)$2
TRUNNER_TEST_OBJS := $$(patsubst %.c,$$(TRUNNER_OUTPUT)/%.test.o, \
@@ -550,6 +552,7 @@ TRUNNER_BPF_SKELS := $$(patsubst %.c,$$(TRUNNER_OUTPUT)/%.skel.h, \
$$(TRUNNER_BPF_SRCS)))
TRUNNER_BPF_LSKELS := $$(patsubst %.c,$$(TRUNNER_OUTPUT)/%.lskel.h, $$(LSKELS) $$(LSKELS_EXTRA))
TRUNNER_BPF_SKELS_LINKED := $$(addprefix $$(TRUNNER_OUTPUT)/,$(LINKED_SKELS))
+TRUNNER_BPF_LSKELS_SIGNED := $$(patsubst %.c,$$(TRUNNER_OUTPUT)/%.lskel.h, $$(LSKELS_SIGNED))
TEST_GEN_FILES += $$(TRUNNER_BPF_OBJS)
# Evaluate rules now with extra TRUNNER_XXX variables above already defined
@@ -604,6 +607,15 @@ $(TRUNNER_BPF_LSKELS): %.lskel.h: %.bpf.o $(BPFTOOL) | $(TRUNNER_OUTPUT)
$(Q)$$(BPFTOOL) gen skeleton -L $$(<:.o=.llinked3.o) name $$(notdir $$(<:.bpf.o=_lskel)) > $$@
$(Q)rm -f $$(<:.o=.llinked1.o) $$(<:.o=.llinked2.o) $$(<:.o=.llinked3.o)
+$(TRUNNER_BPF_LSKELS_SIGNED): %.lskel.h: %.bpf.o $(BPFTOOL) | $(TRUNNER_OUTPUT)
+ $$(call msg,GEN-SKEL,$(TRUNNER_BINARY) (signed),$$@)
+ $(Q)$$(BPFTOOL) gen object $$(<:.o=.llinked1.o) $$<
+ $(Q)$$(BPFTOOL) gen object $$(<:.o=.llinked2.o) $$(<:.o=.llinked1.o)
+ $(Q)$$(BPFTOOL) gen object $$(<:.o=.llinked3.o) $$(<:.o=.llinked2.o)
+ $(Q)diff $$(<:.o=.llinked2.o) $$(<:.o=.llinked3.o)
+ $(Q)$$(BPFTOOL) gen skeleton $(LSKEL_SIGN) $$(<:.o=.llinked3.o) name $$(notdir $$(<:.bpf.o=_lskel)) > $$@
+ $(Q)rm -f $$(<:.o=.llinked1.o) $$(<:.o=.llinked2.o) $$(<:.o=.llinked3.o)
+
$(LINKED_BPF_OBJS): %: $(TRUNNER_OUTPUT)/%
# .SECONDEXPANSION here allows to correctly expand %-deps variables as prerequisites
@@ -653,6 +665,7 @@ $(TRUNNER_TEST_OBJS:.o=.d): $(TRUNNER_OUTPUT)/%.test.d: \
$(TRUNNER_EXTRA_HDRS) \
$(TRUNNER_BPF_SKELS) \
$(TRUNNER_BPF_LSKELS) \
+ $(TRUNNER_BPF_LSKELS_SIGNED) \
$(TRUNNER_BPF_SKELS_LINKED) \
$$(BPFOBJ) | $(TRUNNER_OUTPUT)
@@ -667,6 +680,7 @@ $(foreach N,$(patsubst $(TRUNNER_OUTPUT)/%.o,%,$(TRUNNER_EXTRA_OBJS)), \
$(TRUNNER_EXTRA_OBJS): $(TRUNNER_OUTPUT)/%.o: \
%.c \
$(TRUNNER_EXTRA_HDRS) \
+ $(VERIFY_SIG_HDR) \
$(TRUNNER_TESTS_HDR) \
$$(BPFOBJ) | $(TRUNNER_OUTPUT)
$$(call msg,EXT-OBJ,$(TRUNNER_BINARY),$$@)
@@ -697,6 +711,18 @@ $(OUTPUT)/$(TRUNNER_BINARY): $(TRUNNER_TEST_OBJS) \
endef
+VERIFY_SIG_SETUP := $(CURDIR)/verify_sig_setup.sh
+VERIFY_SIG_HDR := verification_cert.h
+VERIFICATION_CERT := $(BUILD_DIR)/signing_key.der
+PRIVATE_KEY := $(BUILD_DIR)/signing_key.pem
+
+$(VERIFICATION_CERT) $(PRIVATE_KEY): $(VERIFY_SIG_SETUP)
+ $(Q)mkdir -p $(BUILD_DIR)
+ $(Q)$(VERIFY_SIG_SETUP) genkey $(BUILD_DIR)
+
+$(VERIFY_SIG_HDR): $(VERIFICATION_CERT)
+ $(Q)xxd -i -n test_progs_verification_cert $< > $@
+
# Define test_progs test runner.
TRUNNER_TESTS_DIR := prog_tests
TRUNNER_BPF_PROGS_DIR := progs
@@ -716,6 +742,7 @@ TRUNNER_EXTRA_SOURCES := test_progs.c \
disasm.c \
disasm_helpers.c \
json_writer.c \
+ $(VERIFY_SIG_HDR) \
flow_dissector_load.h \
ip_check_defrag_frags.h
TRUNNER_EXTRA_FILES := $(OUTPUT)/urandom_read \
@@ -725,7 +752,7 @@ TRUNNER_EXTRA_FILES := $(OUTPUT)/urandom_read \
$(OUTPUT)/uprobe_multi \
$(TEST_KMOD_TARGETS) \
ima_setup.sh \
- verify_sig_setup.sh \
+ $(VERIFY_SIG_SETUP) \
$(wildcard progs/btf_dump_test_case_*.c) \
$(wildcard progs/*.bpf.o)
TRUNNER_BPF_BUILD_RULE := CLANG_BPF_BUILD_RULE
diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
index 309d9d4a8ace..02a85dda30e6 100644
--- a/tools/testing/selftests/bpf/test_progs.c
+++ b/tools/testing/selftests/bpf/test_progs.c
@@ -14,12 +14,14 @@
#include <netinet/in.h>
#include <sys/select.h>
#include <sys/socket.h>
+#include <linux/keyctl.h>
#include <sys/un.h>
#include <bpf/btf.h>
#include <time.h>
#include "json_writer.h"
#include "network_helpers.h"
+#include "verification_cert.h"
/* backtrace() and backtrace_symbols_fd() are glibc specific,
* use header file when glibc is available and provide stub
@@ -1928,6 +1930,13 @@ static void free_test_states(void)
}
}
+static __u32 register_session_key(const char *key_data, size_t key_data_size)
+{
+ return syscall(__NR_add_key, "asymmetric", "libbpf_session_key",
+ (const void *)key_data, key_data_size,
+ KEY_SPEC_SESSION_KEYRING);
+}
+
int main(int argc, char **argv)
{
static const struct argp argp = {
@@ -1961,6 +1970,10 @@ int main(int argc, char **argv)
/* Use libbpf 1.0 API mode */
libbpf_set_strict_mode(LIBBPF_STRICT_ALL);
libbpf_set_print(libbpf_print_fn);
+ err = register_session_key((const char *)test_progs_verification_cert,
+ test_progs_verification_cert_len);
+ if (err < 0)
+ return err;
traffic_monitor_set_print(traffic_monitor_print_fn);
diff --git a/tools/testing/selftests/bpf/verify_sig_setup.sh b/tools/testing/selftests/bpf/verify_sig_setup.sh
index f2cac42298ba..0834f504f66d 100755
--- a/tools/testing/selftests/bpf/verify_sig_setup.sh
+++ b/tools/testing/selftests/bpf/verify_sig_setup.sh
@@ -32,7 +32,7 @@ usage()
exit 1
}
-setup()
+genkey()
{
local tmp_dir="$1"
@@ -46,8 +46,15 @@ setup()
openssl x509 -in ${tmp_dir}/signing_key.pem -out \
${tmp_dir}/signing_key.der -outform der
- key_id=$(cat ${tmp_dir}/signing_key.der | keyctl padd asymmetric ebpf_testing_key @s)
+}
+setup()
+{
+ local tmp_dir="$1"
+
+ genkey "${tmp_dir}"
+
+ key_id=$(cat ${tmp_dir}/signing_key.der | keyctl padd asymmetric ebpf_testing_key @s)
keyring_id=$(keyctl newring ebpf_testing_keyring @s)
keyctl link $key_id $keyring_id
}
@@ -105,6 +112,8 @@ main()
if [[ "${action}" == "setup" ]]; then
setup "${tmp_dir}"
+ elif [[ "${action}" == "genkey" ]]; then
+ genkey "${tmp_dir}"
elif [[ "${action}" == "cleanup" ]]; then
cleanup "${tmp_dir}"
elif [[ "${action}" == "fsverity-create-sign" ]]; then
--
2.43.0
^ permalink raw reply related
* Re: [PATCH v3 08/12] bpf: Implement signature verification for BPF programs
From: Paul Moore @ 2025-08-13 21:02 UTC (permalink / raw)
To: KP Singh; +Cc: bpf, linux-security-module, bboscaccy, kys, ast, daniel, andrii
In-Reply-To: <20250813205526.2992911-9-kpsingh@kernel.org>
On Wed, Aug 13, 2025 at 4:55 PM KP Singh <kpsingh@kernel.org> wrote:
>
> This patch extends the BPF_PROG_LOAD command by adding three new fields
> to `union bpf_attr` in the user-space API:
>
> - signature: A pointer to the signature blob.
> - signature_size: The size of the signature blob.
> - keyring_id: The serial number of a loaded kernel keyring (e.g.,
> the user or session keyring) containing the trusted public keys.
>
> When a BPF program is loaded with a signature, the kernel:
>
> 1. Retrieves the trusted keyring using the provided `keyring_id`.
> 2. Verifies the supplied signature against the BPF program's
> instruction buffer.
> 3. If the signature is valid and was generated by a key in the trusted
> keyring, the program load proceeds.
> 4. If no signature is provided, the load proceeds as before, allowing
> for backward compatibility. LSMs can chose to restrict unsigned
> programs and implement a security policy.
> 5. If signature verification fails for any reason,
> the program is not loaded.
>
> Signed-off-by: KP Singh <kpsingh@kernel.org>
> ---
> crypto/asymmetric_keys/pkcs7_verify.c | 1 +
> include/linux/verification.h | 1 +
> include/uapi/linux/bpf.h | 10 +++++++
> kernel/bpf/helpers.c | 2 +-
> kernel/bpf/syscall.c | 42 ++++++++++++++++++++++++++-
> tools/include/uapi/linux/bpf.h | 10 +++++++
> tools/lib/bpf/bpf.c | 2 +-
> 7 files changed, 65 insertions(+), 3 deletions(-)
It's nice to see a v3 revision, but it would be good to see some
comments on Blaise's reply to your v2 revision. From what I can see
it should enable the different use cases and requirements that have
been posted.
https://lore.kernel.org/linux-security-module/87sei58vy3.fsf@microsoft.com
--
paul-moore.com
^ permalink raw reply
page: next (older) | prev (newer) | latest
- recent:[subjects (threaded)|topics (new)|topics (active)]
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox