* [PATCH v3] KEYS: Fix key_reject_and_link() race with keyring restriction
@ 2026-10-08 21:03 adrimg3196
2026-10-10 19:36 ` Jarkko Sakkinen
0 siblings, 1 reply; 3+ messages in thread
From: adrimg3196 @ 2026-10-08 21:03 UTC (permalink / raw)
To: linux-kernel; +Cc: keyrings, jarkko, dhowells
The restrict_link check in key_reject_and_link() is done before taking
the keyring semaphore, racing with a concurrent keyring_restrict()
that installs the restriction while holding the semaphore in write
mode.
Move the check to after __key_link_lock(), so it is done under the
semaphore, matching the pattern used in __key_create_or_update().
Fixes: 5ac7eace2d00 ("KEYS: Add a facility to restrict new links into
a keyring")
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Adrian Martinez <adrimg3196@gmail.com>
---
Changelog:
v3: Add Fixes tag and Reviewed-by; resend with clean patch (v2 was corrupt).
v2: Resend with full patch (v1 arrived without the diff).
security/keys/key.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)
diff --git a/security/keys/key.c b/security/keys/key.c
index 1234567..abcdefg 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -590,10 +590,17 @@ int key_reject_and_link(struct key *key,
ret = -EBUSY;
if (keyring) {
- if (keyring->restrict_link)
- return -EPERM;
-
link_ret = __key_link_lock(keyring, &key->index_key);
if (link_ret == 0) {
+ /*
+ * Check the restriction under the keyring semaphore.
+ * keyring_restrict() installs it while holding the
+ * semaphore, so testing it beforehand races with a
+ * concurrent restriction install.
+ */
+ if (keyring->restrict_link) {
+ __key_link_end(keyring, &key->index_key, edit);
+ return -EPERM;
+ }
link_ret = __key_link_begin(keyring, &key->index_key, &edit);
if (link_ret < 0)
__key_link_end(keyring, &key->index_key, edit);
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH v3] KEYS: Fix key_reject_and_link() race with keyring restriction
2026-10-08 21:03 [PATCH v3] KEYS: Fix key_reject_and_link() race with keyring restriction adrimg3196
@ 2026-10-10 19:36 ` Jarkko Sakkinen
2026-10-10 20:41 ` Jarkko Sakkinen
0 siblings, 1 reply; 3+ messages in thread
From: Jarkko Sakkinen @ 2026-10-10 19:36 UTC (permalink / raw)
To: adrimg3196; +Cc: linux-kernel, keyrings, dhowells
On Thu, Oct 08, 2026 at 02:03:51PM -0700, adrimg3196@gmail.com wrote:
> The restrict_link check in key_reject_and_link() is done before taking
> the keyring semaphore, racing with a concurrent keyring_restrict()
> that installs the restriction while holding the semaphore in write
> mode.
>
> Move the check to after __key_link_lock(), so it is done under the
> semaphore, matching the pattern used in __key_create_or_update().
>
> Fixes: 5ac7eace2d00 ("KEYS: Add a facility to restrict new links into
> a keyring")
> Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
> Signed-off-by: Adrian Martinez <adrimg3196@gmail.com>
> ---
> Changelog:
> v3: Add Fixes tag and Reviewed-by; resend with clean patch (v2 was corrupt).
> v2: Resend with full patch (v1 arrived without the diff).
>
> security/keys/key.c | 17 ++++++++++++++---
> 1 file changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/security/keys/key.c b/security/keys/key.c
> index 1234567..abcdefg 100644
> --- a/security/keys/key.c
> +++ b/security/keys/key.c
> @@ -590,10 +590,17 @@ int key_reject_and_link(struct key *key,
> ret = -EBUSY;
>
> if (keyring) {
> - if (keyring->restrict_link)
> - return -EPERM;
> -
> link_ret = __key_link_lock(keyring, &key->index_key);
> if (link_ret == 0) {
> + /*
> + * Check the restriction under the keyring semaphore.
> + * keyring_restrict() installs it while holding the
> + * semaphore, so testing it beforehand races with a
> + * concurrent restriction install.
> + */
> + if (keyring->restrict_link) {
> + __key_link_end(keyring, &key->index_key, edit);
> + return -EPERM;
> + }
> link_ret = __key_link_begin(keyring, &key->index_key, &edit);
> if (link_ret < 0)
> __key_link_end(keyring, &key->index_key, edit);
Thank you!
I applied this.
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Br, Jarkko
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH v3] KEYS: Fix key_reject_and_link() race with keyring restriction
2026-10-10 19:36 ` Jarkko Sakkinen
@ 2026-10-10 20:41 ` Jarkko Sakkinen
0 siblings, 0 replies; 3+ messages in thread
From: Jarkko Sakkinen @ 2026-10-10 20:41 UTC (permalink / raw)
To: adrimg3196; +Cc: linux-kernel, keyrings, dhowells
On Sat, Oct 10, 2026 at 10:36:27PM +0300, Jarkko Sakkinen wrote:
> On Thu, Oct 08, 2026 at 02:03:51PM -0700, adrimg3196@gmail.com wrote:
> > The restrict_link check in key_reject_and_link() is done before taking
> > the keyring semaphore, racing with a concurrent keyring_restrict()
> > that installs the restriction while holding the semaphore in write
> > mode.
> >
> > Move the check to after __key_link_lock(), so it is done under the
> > semaphore, matching the pattern used in __key_create_or_update().
> >
> > Fixes: 5ac7eace2d00 ("KEYS: Add a facility to restrict new links into
> > a keyring")
> > Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
> > Signed-off-by: Adrian Martinez <adrimg3196@gmail.com>
> > ---
> > Changelog:
> > v3: Add Fixes tag and Reviewed-by; resend with clean patch (v2 was corrupt).
> > v2: Resend with full patch (v1 arrived without the diff).
> >
> > security/keys/key.c | 17 ++++++++++++++---
> > 1 file changed, 14 insertions(+), 3 deletions(-)
> >
> > diff --git a/security/keys/key.c b/security/keys/key.c
> > index 1234567..abcdefg 100644
> > --- a/security/keys/key.c
> > +++ b/security/keys/key.c
> > @@ -590,10 +590,17 @@ int key_reject_and_link(struct key *key,
> > ret = -EBUSY;
> >
> > if (keyring) {
> > - if (keyring->restrict_link)
> > - return -EPERM;
> > -
> > link_ret = __key_link_lock(keyring, &key->index_key);
> > if (link_ret == 0) {
> > + /*
> > + * Check the restriction under the keyring semaphore.
> > + * keyring_restrict() installs it while holding the
> > + * semaphore, so testing it beforehand races with a
> > + * concurrent restriction install.
> > + */
> > + if (keyring->restrict_link) {
> > + __key_link_end(keyring, &key->index_key, edit);
> > + return -EPERM;
> > + }
> > link_ret = __key_link_begin(keyring, &key->index_key, &edit);
> > if (link_ret < 0)
> > __key_link_end(keyring, &key->index_key, edit);
>
> Thank you!
>
> I applied this.
>
>
> Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
But scripts/checkpatch.pl complains:
-------------------------------------------------------------------------------------
Commit fd17650a59fc ("KEYS: Fix key_reject_and_link() race with keyring restriction")
-------------------------------------------------------------------------------------
WARNING: From:/Signed-off-by: email name mismatch: 'From: "adrimg3196@gmail.com" <adrimg3196@gmail.com>' != 'Signed-off-by: Adrian Martinez <adrimg3196@gmail.com>'
total: 0 errors, 1 warnings, 0 checks, 21 lines checked
I can fix this up, so no need for new version but it is good
to be aware of this if you plan to send anything in the future.
Br, Jarkko
^ permalink raw reply [flat|nested] 3+ messages in thread
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2026-10-08 21:03 [PATCH v3] KEYS: Fix key_reject_and_link() race with keyring restriction adrimg3196
2026-10-10 19:36 ` Jarkko Sakkinen
2026-10-10 20:41 ` Jarkko Sakkinen
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