diff options
Diffstat (limited to 'security/keys')
| -rw-r--r-- | security/keys/keyring.c | 41 | ||||
| -rw-r--r-- | security/keys/request_key.c | 2 |
2 files changed, 23 insertions, 20 deletions
diff --git a/security/keys/keyring.c b/security/keys/keyring.c index 29de5ee3457..3f425a65906 100644 --- a/security/keys/keyring.c +++ b/security/keys/keyring.c @@ -20,6 +20,11 @@ #include <linux/uaccess.h> #include "internal.h" +#define rcu_dereference_locked_keyring(keyring) \ + (rcu_dereference_protected( \ + (keyring)->payload.subscriptions, \ + rwsem_is_locked((struct rw_semaphore *)&(keyring)->sem))) + /* * when plumbing the depths of the key tree, this sets a hard limit set on how * deep we're willing to go @@ -199,8 +204,7 @@ static long keyring_read(const struct key *keyring, int loop, ret; ret = 0; - klist = keyring->payload.subscriptions; - + klist = rcu_dereference_locked_keyring(keyring); if (klist) { /* calculate how much data we could return */ qty = klist->nkeys * sizeof(key_serial_t); @@ -524,9 +528,8 @@ struct key *find_keyring_by_name(const char *name, bool skip_perm_check) struct key *keyring; int bucket; - keyring = ERR_PTR(-EINVAL); if (!name) - goto error; + return ERR_PTR(-EINVAL); bucket = keyring_hash(name); @@ -553,17 +556,18 @@ struct key *find_keyring_by_name(const char *name, bool skip_perm_check) KEY_SEARCH) < 0) continue; - /* we've got a match */ - atomic_inc(&keyring->usage); - read_unlock(&keyring_name_lock); - goto error; + /* we've got a match but we might end up racing with + * key_cleanup() if the keyring is currently 'dead' + * (ie. it has a zero usage count) */ + if (!atomic_inc_not_zero(&keyring->usage)) + continue; + goto out; } } - read_unlock(&keyring_name_lock); keyring = ERR_PTR(-ENOKEY); - -error: +out: + read_unlock(&keyring_name_lock); return keyring; } /* end find_keyring_by_name() */ @@ -719,8 +723,7 @@ int __key_link(struct key *keyring, struct key *key) } /* see if there's a matching key we can displace */ - klist = keyring->payload.subscriptions; - + klist = rcu_dereference_locked_keyring(keyring); if (klist && klist->nkeys > 0) { struct key_type *type = key->type; @@ -764,8 +767,6 @@ int __key_link(struct key *keyring, struct key *key) if (ret < 0) goto error2; - klist = keyring->payload.subscriptions; - if (klist && klist->nkeys < klist->maxkeys) { /* there's sufficient slack space to add directly */ atomic_inc(&key->usage); @@ -867,7 +868,7 @@ int key_unlink(struct key *keyring, struct key *key) down_write(&keyring->sem); - klist = keyring->payload.subscriptions; + klist = rcu_dereference_locked_keyring(keyring); if (klist) { /* search the keyring for the key */ for (loop = 0; loop < klist->nkeys; loop++) @@ -958,7 +959,7 @@ int keyring_clear(struct key *keyring) /* detach the pointer block with the locks held */ down_write(&keyring->sem); - klist = keyring->payload.subscriptions; + klist = rcu_dereference_locked_keyring(keyring); if (klist) { /* adjust the quota */ key_payload_reserve(keyring, @@ -990,7 +991,9 @@ EXPORT_SYMBOL(keyring_clear); */ static void keyring_revoke(struct key *keyring) { - struct keyring_list *klist = keyring->payload.subscriptions; + struct keyring_list *klist; + + klist = rcu_dereference_locked_keyring(keyring); /* adjust the quota */ key_payload_reserve(keyring, 0); @@ -1024,7 +1027,7 @@ void keyring_gc(struct key *keyring, time_t limit) down_write(&keyring->sem); - klist = keyring->payload.subscriptions; + klist = rcu_dereference_locked_keyring(keyring); if (!klist) goto no_klist; diff --git a/security/keys/request_key.c b/security/keys/request_key.c index 1bc38587adc..ac49c8aacbf 100644 --- a/security/keys/request_key.c +++ b/security/keys/request_key.c @@ -94,7 +94,7 @@ static int call_sbin_request_key(struct key_construction *cons, } /* attach the auth key to the session keyring */ - ret = __key_link(keyring, authkey); + ret = key_link(keyring, authkey); if (ret < 0) goto error_link; |