[PATCH v2 4/6] KEYS: load key flags and expiry time atomically in keyring_search_iterator()

Eric Biggers
2017-09-26T20:14:43Z

Similar to the case for key_validate(), we should load the key ->flags
and ->expiry once atomically in keyring_search_iterator(), since they
can be changed concurrently whenever the key semaphore isn't held.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
security/keys/keyring.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index 7fc661f492d3..1dfff0eac474 100644
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -553,7 +553,7 @@ static int keyring_search_iterator(const void *object, void *iterator_data)
{
struct keyring_search_context *ctx = iterator_data;
const struct key *key = keyring_ptr_to_key(object);
- unsigned long kflags = key->flags;
+ unsigned long kflags = READ_ONCE(key->flags);

kenter("{%d}", key->serial);

@@ -565,6 +565,8 @@ static int keyring_search_iterator(const void *object, void *iterator_data)

/* skip invalidated, revoked and expired keys */
if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
+ time_t expiry = READ_ONCE(key->expiry);
+
if (kflags & ((1 << KEY_FLAG_INVALIDATED) |
(1 << KEY_FLAG_REVOKED))) {
ctx->result = ERR_PTR(-EKEYREVOKED);
@@ -572,7 +574,7 @@ static int keyring_search_iterator(const void *object, void *iterator_data)
goto skipped;
}

- if (key->expiry && ctx->now.tv_sec >= key->expiry) {
+ if (expiry && ctx->now.tv_sec >= expiry) {
if (!(ctx->flags & KEYRING_SEARCH_SKIP_EXPIRED))
ctx->result = ERR_PTR(-EKEYEXPIRED);
kleave(" = %d [expire]", ctx->skipped_ret);
--
2.14.1.992.g2c7b836f3a-goog