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| author |   Eric Biggers <ebiggers@google.com> | 2017-09-27 12:50:44 -0700 |
|---|---|---|
| committer |   David Howells <dhowells@redhat.com> | 2017-10-18 09:12:41 +0100 |
| commit | 1823d475a5eeaa0f52789b1b7e2d31a592ae92ea (patch) | |
| tree | 0cc97d27ac4815b342887b85d5b8f274dd3d4095 | |
| parent | KEYS: don't let add_key() update an uninstantiated key (diff) | |
| download | linux-dev-1823d475a5eeaa0f52789b1b7e2d31a592ae92ea.tar.xz linux-dev-1823d475a5eeaa0f52789b1b7e2d31a592ae92ea.zip | |
KEYS: load key flags and expiry time atomically in key_validate()
In key_validate(), load the flags and expiry time once atomically, since
these can change concurrently if key_validate() is called without the
key semaphore held. And we don't want to get inconsistent results if a
variable is referenced multiple times. For example, key->expiry was
referenced in both 'if (key->expiry)' and in 'if (now.tv_sec >=
key->expiry)', making it theoretically possible to see a spurious
EKEYEXPIRED while the expiration time was being removed, i.e. set to 0.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
| -rw-r--r-- | security/keys/permission.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/security/keys/permission.c b/security/keys/permission.c index 732cc0beffdf..a72b4dd70c8a 100644 --- a/security/keys/permission.c +++ b/security/keys/permission.c @@ -88,7 +88,8 @@ EXPORT_SYMBOL(key_task_permission); */ int key_validate(const struct key *key) { - unsigned long flags = key->flags; + unsigned long flags = READ_ONCE(key->flags); + time_t expiry = READ_ONCE(key->expiry); if (flags & (1 << KEY_FLAG_INVALIDATED)) return -ENOKEY; @@ -99,9 +100,9 @@ int key_validate(const struct key *key) return -EKEYREVOKED; /* check it hasn't expired */ - if (key->expiry) { + if (expiry) { struct timespec now = current_kernel_time(); - if (now.tv_sec >= key->expiry) + if (now.tv_sec >= expiry) return -EKEYEXPIRED; } |