From: Eric Biggers <ebiggers3@gmail.com>
To: linux-security-module@vger.kernel.org
Subject: [PATCH v3 4/7] KEYS: load key flags and expiry time atomically in key_validate()
Date: Wed, 27 Sep 2017 19:50:44 +0000 [thread overview]
Message-ID: <20170927195047.122358-5-ebiggers3@gmail.com> (raw)
In-Reply-To: <20170927195047.122358-1-ebiggers3@gmail.com>
From: Eric Biggers <ebiggers@google.com>
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>
---
security/keys/permission.c | 7 ++++---
1 file 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;
}
--
2.14.2.822.g60be5d43e6-goog
WARNING: multiple messages have this Message-ID (diff)
From: Eric Biggers <ebiggers3@gmail.com>
To: keyrings@vger.kernel.org
Cc: David Howells <dhowells@redhat.com>,
Michael Halcrow <mhalcrow@google.com>,
linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org, Eric Biggers <ebiggers@google.com>
Subject: [PATCH v3 4/7] KEYS: load key flags and expiry time atomically in key_validate()
Date: Wed, 27 Sep 2017 12:50:44 -0700 [thread overview]
Message-ID: <20170927195047.122358-5-ebiggers3@gmail.com> (raw)
In-Reply-To: <20170927195047.122358-1-ebiggers3@gmail.com>
From: Eric Biggers <ebiggers@google.com>
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>
---
security/keys/permission.c | 7 ++++---
1 file 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;
}
--
2.14.2.822.g60be5d43e6-goog
WARNING: multiple messages have this Message-ID (diff)
From: ebiggers3@gmail.com (Eric Biggers)
To: linux-security-module@vger.kernel.org
Subject: [PATCH v3 4/7] KEYS: load key flags and expiry time atomically in key_validate()
Date: Wed, 27 Sep 2017 12:50:44 -0700 [thread overview]
Message-ID: <20170927195047.122358-5-ebiggers3@gmail.com> (raw)
In-Reply-To: <20170927195047.122358-1-ebiggers3@gmail.com>
From: Eric Biggers <ebiggers@google.com>
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>
---
security/keys/permission.c | 7 ++++---
1 file 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;
}
--
2.14.2.822.g60be5d43e6-goog
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next prev parent reply other threads:[~2017-09-27 19:50 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-27 19:50 [PATCH v3 0/7] KEYS: instantiation and atomicity fixes Eric Biggers
2017-09-27 19:50 ` Eric Biggers
2017-09-27 19:50 ` Eric Biggers
2017-09-27 19:50 ` [PATCH v3 1/7] KEYS: don't let add_key() update an uninstantiated key Eric Biggers
2017-09-27 19:50 ` Eric Biggers
2017-09-27 19:50 ` Eric Biggers
2017-09-27 19:50 ` [PATCH v3 2/7] KEYS: fix race between updating and finding negative key Eric Biggers
2017-09-27 19:50 ` Eric Biggers
2017-09-27 19:50 ` Eric Biggers
2017-09-27 19:50 ` [PATCH v3 3/7] KEYS: load key flags atomically in key_is_instantiated() Eric Biggers
2017-09-27 19:50 ` Eric Biggers
2017-09-27 19:50 ` Eric Biggers
2017-09-27 19:50 ` Eric Biggers [this message]
2017-09-27 19:50 ` [PATCH v3 4/7] KEYS: load key flags and expiry time atomically in key_validate() Eric Biggers
2017-09-27 19:50 ` Eric Biggers
2017-09-27 19:50 ` [PATCH v3 5/7] KEYS: load key flags and expiry time atomically in keyring_search_iterator() Eric Biggers
2017-09-27 19:50 ` Eric Biggers
2017-09-27 19:50 ` Eric Biggers
2017-09-27 19:50 ` [PATCH v3 6/7] KEYS: load key flags and expiry time atomically in proc_keys_show() Eric Biggers
2017-09-27 19:50 ` Eric Biggers
2017-09-27 19:50 ` Eric Biggers
2017-09-27 19:50 ` [PATCH v3 7/7] KEYS: remove KEY_FLAG_NEGATIVE Eric Biggers
2017-09-27 19:50 ` Eric Biggers
2017-09-27 19:50 ` Eric Biggers
2017-10-04 14:34 ` [PATCH v3 1/7] KEYS: don't let add_key() update an uninstantiated key David Howells
2017-10-04 14:34 ` David Howells
2017-10-04 14:34 ` David Howells
2017-10-04 16:33 ` [PATCH v3 2/7] KEYS: fix race between updating and finding negative key David Howells
2017-10-04 16:33 ` David Howells
2017-10-04 16:33 ` David Howells
2017-10-12 15:27 ` [PATCH v3 1/7] KEYS: don't let add_key() update an uninstantiated key David Howells
2017-10-12 15:27 ` David Howells
2017-10-12 15:27 ` David Howells
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