diff options
Diffstat (limited to '')
| -rw-r--r-- | security/keys/gc.c | 11 | ||||
| -rw-r--r-- | security/keys/internal.h | 2 | ||||
| -rw-r--r-- | security/keys/key.c | 23 | ||||
| -rw-r--r-- | security/keys/keyring.c | 68 |
4 files changed, 90 insertions, 14 deletions
diff --git a/security/keys/gc.c b/security/keys/gc.c index 44789256c88c..15b9ddf510e4 100644 --- a/security/keys/gc.c +++ b/security/keys/gc.c @@ -229,6 +229,9 @@ continue_scanning: set_bit(KEY_FLAG_DEAD, &key->flags); key->perm = 0; goto skip_dead_key; + } else if (key->type == &key_type_keyring && + key->restrict_link) { + goto found_restricted_keyring; } } @@ -334,6 +337,14 @@ found_unreferenced_key: gc_state |= KEY_GC_REAP_AGAIN; goto maybe_resched; + /* We found a restricted keyring and need to update the restriction if + * it is associated with the dead key type. + */ +found_restricted_keyring: + spin_unlock(&key_serial_lock); + keyring_restriction_gc(key, key_gc_dead_keytype); + goto maybe_resched; + /* We found a keyring and we need to check the payload for links to * dead or expired keys. We don't flag another reap immediately as we * have to wait for the old payload to be destroyed by RCU before we diff --git a/security/keys/internal.h b/security/keys/internal.h index 6bee06ae026d..24762ae9a198 100644 --- a/security/keys/internal.h +++ b/security/keys/internal.h @@ -168,6 +168,8 @@ extern void key_change_session_keyring(struct callback_head *twork); extern struct work_struct key_gc_work; extern unsigned key_gc_delay; extern void keyring_gc(struct key *keyring, time_t limit); +extern void keyring_restriction_gc(struct key *keyring, + struct key_type *dead_type); extern void key_schedule_gc(time_t gc_at); extern void key_schedule_gc_links(void); extern void key_gc_keytype(struct key_type *ktype); diff --git a/security/keys/key.c b/security/keys/key.c index 27fc1bb40034..2ea5967121de 100644 --- a/security/keys/key.c +++ b/security/keys/key.c @@ -201,12 +201,15 @@ serial_exists: * @cred: The credentials specifying UID namespace. * @perm: The permissions mask of the new key. * @flags: Flags specifying quota properties. - * @restrict_link: Optional link restriction method for new keyrings. + * @restrict_link: Optional link restriction for new keyrings. * * Allocate a key of the specified type with the attributes given. The key is * returned in an uninstantiated state and the caller needs to instantiate the * key before returning. * + * The restrict_link structure (if not NULL) will be freed when the + * keyring is destroyed, so it must be dynamically allocated. + * * The user's key count quota is updated to reflect the creation of the key and * the user's key data quota has the default for the key type reserved. The * instantiation function should amend this as necessary. If insufficient @@ -225,7 +228,7 @@ serial_exists: struct key *key_alloc(struct key_type *type, const char *desc, kuid_t uid, kgid_t gid, const struct cred *cred, key_perm_t perm, unsigned long flags, - key_restrict_link_func_t restrict_link) + struct key_restriction *restrict_link) { struct key_user *user = NULL; struct key *key; @@ -497,9 +500,11 @@ int key_instantiate_and_link(struct key *key, } if (keyring) { - if (keyring->restrict_link) { - ret = keyring->restrict_link(keyring, key->type, - &prep.payload, NULL); + if (keyring->restrict_link && keyring->restrict_link->check) { + struct key_restriction *keyres = keyring->restrict_link; + + ret = keyres->check(keyring, key->type, &prep.payload, + keyres->key); if (ret < 0) goto error; } @@ -804,7 +809,7 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref, struct key *keyring, *key = NULL; key_ref_t key_ref; int ret; - key_restrict_link_func_t restrict_link = NULL; + struct key_restriction *restrict_link = NULL; /* look up the key type to see if it's one of the registered kernel * types */ @@ -850,9 +855,9 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref, } index_key.desc_len = strlen(index_key.description); - if (restrict_link) { - ret = restrict_link(keyring, index_key.type, &prep.payload, - NULL); + if (restrict_link && restrict_link->check) { + ret = restrict_link->check(keyring, index_key.type, + &prep.payload, restrict_link->key); if (ret < 0) { key_ref = ERR_PTR(ret); goto error_free_prep; diff --git a/security/keys/keyring.c b/security/keys/keyring.c index 2ccc66ec35d7..838334fec6ce 100644 --- a/security/keys/keyring.c +++ b/security/keys/keyring.c @@ -394,6 +394,13 @@ static void keyring_destroy(struct key *keyring) write_unlock(&keyring_name_lock); } + if (keyring->restrict_link) { + struct key_restriction *keyres = keyring->restrict_link; + + key_put(keyres->key); + kfree(keyres); + } + assoc_array_destroy(&keyring->keys, &keyring_assoc_array_ops); } @@ -492,7 +499,7 @@ static long keyring_read(const struct key *keyring, struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid, const struct cred *cred, key_perm_t perm, unsigned long flags, - key_restrict_link_func_t restrict_link, + struct key_restriction *restrict_link, struct key *dest) { struct key *keyring; @@ -523,8 +530,8 @@ EXPORT_SYMBOL(keyring_alloc); * passing KEY_ALLOC_BYPASS_RESTRICTION to key_instantiate_and_link() when * adding a key to a keyring. * - * This is meant to be passed as the restrict_link parameter to - * keyring_alloc(). + * This is meant to be stored in a key_restriction structure which is passed + * in the restrict_link parameter to keyring_alloc(). */ int restrict_link_reject(struct key *keyring, const struct key_type *type, @@ -1220,9 +1227,10 @@ void __key_link_end(struct key *keyring, */ static int __key_link_check_restriction(struct key *keyring, struct key *key) { - if (!keyring->restrict_link) + if (!keyring->restrict_link || !keyring->restrict_link->check) return 0; - return keyring->restrict_link(keyring, key->type, &key->payload, NULL); + return keyring->restrict_link->check(keyring, key->type, &key->payload, + keyring->restrict_link->key); } /** @@ -1426,3 +1434,53 @@ do_gc: up_write(&keyring->sem); kleave(" [gc]"); } + +/* + * Garbage collect restriction pointers from a keyring. + * + * Keyring restrictions are associated with a key type, and must be cleaned + * up if the key type is unregistered. The restriction is altered to always + * reject additional keys so a keyring cannot be opened up by unregistering + * a key type. + * + * Not called with any keyring locks held. The keyring's key struct will not + * be deallocated under us as only our caller may deallocate it. + * + * The caller is required to hold key_types_sem and dead_type->sem. This is + * fulfilled by key_gc_keytype() holding the locks on behalf of + * key_garbage_collector(), which it invokes on a workqueue. + */ +void keyring_restriction_gc(struct key *keyring, struct key_type *dead_type) +{ + struct key_restriction *keyres; + + kenter("%x{%s}", keyring->serial, keyring->description ?: ""); + + /* + * keyring->restrict_link is only assigned at key allocation time + * or with the key type locked, so the only values that could be + * concurrently assigned to keyring->restrict_link are for key + * types other than dead_type. Given this, it's ok to check + * the key type before acquiring keyring->sem. + */ + if (!dead_type || !keyring->restrict_link || + keyring->restrict_link->keytype != dead_type) { + kleave(" [no restriction gc]"); + return; + } + + /* Lock the keyring to ensure that a link is not in progress */ + down_write(&keyring->sem); + + keyres = keyring->restrict_link; + + keyres->check = restrict_link_reject; + + key_put(keyres->key); + keyres->key = NULL; + keyres->keytype = NULL; + + up_write(&keyring->sem); + + kleave(" [restriction gc]"); +} |