diff options
Diffstat (limited to 'security/keys/request_key.c')
| -rw-r--r-- | security/keys/request_key.c | 166 |
1 files changed, 122 insertions, 44 deletions
diff --git a/security/keys/request_key.c b/security/keys/request_key.c index 0ea52d25a6bd..a3dc0d460def 100644 --- a/security/keys/request_key.c +++ b/security/keys/request_key.c @@ -39,8 +39,14 @@ static int key_wait_bit_intr(void *flags) return signal_pending(current) ? -ERESTARTSYS : 0; } -/* - * call to complete the construction of a key +/** + * complete_request_key - Complete the construction of a key. + * @cons: The key construction record. + * @error: The success or failute of the construction. + * + * Complete the attempt to construct a key. The key will be negated + * if an error is indicated. The authorisation key will be revoked + * unconditionally. */ void complete_request_key(struct key_construction *cons, int error) { @@ -58,23 +64,33 @@ void complete_request_key(struct key_construction *cons, int error) } EXPORT_SYMBOL(complete_request_key); +/* + * Initialise a usermode helper that is going to have a specific session + * keyring. + * + * This is called in context of freshly forked kthread before kernel_execve(), + * so we can simply install the desired session_keyring at this point. + */ static int umh_keys_init(struct subprocess_info *info) { struct cred *cred = (struct cred*)current_cred(); struct key *keyring = info->data; - /* - * This is called in context of freshly forked kthread before - * kernel_execve(), we can just change our ->session_keyring. - */ + return install_session_keyring_to_cred(cred, keyring); } +/* + * Clean up a usermode helper with session keyring. + */ static void umh_keys_cleanup(struct subprocess_info *info) { struct key *keyring = info->data; key_put(keyring); } +/* + * Call a usermode helper with a specific session keyring. + */ static int call_usermodehelper_keys(char *path, char **argv, char **envp, struct key *session_keyring, enum umh_wait wait) { @@ -91,7 +107,7 @@ static int call_usermodehelper_keys(char *path, char **argv, char **envp, } /* - * request userspace finish the construction of a key + * Request userspace finish the construction of a key * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>" */ static int call_sbin_request_key(struct key_construction *cons, @@ -198,8 +214,9 @@ error_alloc: } /* - * call out to userspace for key construction - * - we ignore program failure and go on key status instead + * Call out to userspace for key construction. + * + * Program failure is ignored in favour of key status. */ static int construct_key(struct key *key, const void *callout_info, size_t callout_len, void *aux, @@ -246,9 +263,10 @@ static int construct_key(struct key *key, const void *callout_info, } /* - * get the appropriate destination keyring for the request - * - we return whatever keyring we select with an extra reference upon it which - * the caller must release + * Get the appropriate destination keyring for the request. + * + * The keyring selected is returned with an extra reference upon it which the + * caller must release. */ static void construct_get_dest_keyring(struct key **_dest_keyring) { @@ -321,9 +339,11 @@ static void construct_get_dest_keyring(struct key **_dest_keyring) } /* - * allocate a new key in under-construction state and attempt to link it in to - * the requested place - * - may return a key that's already under construction instead + * Allocate a new key in under-construction state and attempt to link it in to + * the requested keyring. + * + * May return a key that's already under construction instead if there was a + * race between two thread calling request_key(). */ static int construct_alloc_key(struct key_type *type, const char *description, @@ -332,8 +352,8 @@ static int construct_alloc_key(struct key_type *type, struct key_user *user, struct key **_key) { - struct keyring_list *prealloc; const struct cred *cred = current_cred(); + unsigned long prealloc; struct key *key; key_ref_t key_ref; int ret; @@ -414,7 +434,7 @@ alloc_failed: } /* - * commence key construction + * Commence key construction. */ static struct key *construct_key_and_link(struct key_type *type, const char *description, @@ -465,12 +485,32 @@ construction_failed: return ERR_PTR(ret); } -/* - * request a key - * - search the process's keyrings - * - check the list of keys being created or updated - * - call out to userspace for a key if supplementary info was provided - * - cache the key in an appropriate keyring +/** + * request_key_and_link - Request a key and cache it in a keyring. + * @type: The type of key we want. + * @description: The searchable description of the key. + * @callout_info: The data to pass to the instantiation upcall (or NULL). + * @callout_len: The length of callout_info. + * @aux: Auxiliary data for the upcall. + * @dest_keyring: Where to cache the key. + * @flags: Flags to key_alloc(). + * + * A key matching the specified criteria is searched for in the process's + * keyrings and returned with its usage count incremented if found. Otherwise, + * if callout_info is not NULL, a key will be allocated and some service + * (probably in userspace) will be asked to instantiate it. + * + * If successfully found or created, the key will be linked to the destination + * keyring if one is provided. + * + * Returns a pointer to the key if successful; -EACCES, -ENOKEY, -EKEYREVOKED + * or -EKEYEXPIRED if an inaccessible, negative, revoked or expired key was + * found; -ENOKEY if no key was found and no @callout_info was given; -EDQUOT + * if insufficient key quota was available to create a new key; or -ENOMEM if + * insufficient memory was available. + * + * If the returned key was created, then it may still be under construction, + * and wait_for_key_construction() should be used to wait for that to complete. */ struct key *request_key_and_link(struct key_type *type, const char *description, @@ -524,8 +564,16 @@ error: return key; } -/* - * wait for construction of a key to complete +/** + * wait_for_key_construction - Wait for construction of a key to complete + * @key: The key being waited for. + * @intr: Whether to wait interruptibly. + * + * Wait for a key to finish being constructed. + * + * Returns 0 if successful; -ERESTARTSYS if the wait was interrupted; -ENOKEY + * if the key was negated; or -EKEYREVOKED or -EKEYEXPIRED if the key was + * revoked or expired. */ int wait_for_key_construction(struct key *key, bool intr) { @@ -542,12 +590,19 @@ int wait_for_key_construction(struct key *key, bool intr) } EXPORT_SYMBOL(wait_for_key_construction); -/* - * request a key - * - search the process's keyrings - * - check the list of keys being created or updated - * - call out to userspace for a key if supplementary info was provided - * - waits uninterruptible for creation to complete +/** + * request_key - Request a key and wait for construction + * @type: Type of key. + * @description: The searchable description of the key. + * @callout_info: The data to pass to the instantiation upcall (or NULL). + * + * As for request_key_and_link() except that it does not add the returned key + * to a keyring if found, new keys are always allocated in the user's quota, + * the callout_info must be a NUL-terminated string and no auxiliary data can + * be passed. + * + * Furthermore, it then works as wait_for_key_construction() to wait for the + * completion of keys undergoing construction with a non-interruptible wait. */ struct key *request_key(struct key_type *type, const char *description, @@ -572,12 +627,19 @@ struct key *request_key(struct key_type *type, } EXPORT_SYMBOL(request_key); -/* - * request a key with auxiliary data for the upcaller - * - search the process's keyrings - * - check the list of keys being created or updated - * - call out to userspace for a key if supplementary info was provided - * - waits uninterruptible for creation to complete +/** + * request_key_with_auxdata - Request a key with auxiliary data for the upcaller + * @type: The type of key we want. + * @description: The searchable description of the key. + * @callout_info: The data to pass to the instantiation upcall (or NULL). + * @callout_len: The length of callout_info. + * @aux: Auxiliary data for the upcall. + * + * As for request_key_and_link() except that it does not add the returned key + * to a keyring if found and new keys are always allocated in the user's quota. + * + * Furthermore, it then works as wait_for_key_construction() to wait for the + * completion of keys undergoing construction with a non-interruptible wait. */ struct key *request_key_with_auxdata(struct key_type *type, const char *description, @@ -602,10 +664,18 @@ struct key *request_key_with_auxdata(struct key_type *type, EXPORT_SYMBOL(request_key_with_auxdata); /* - * request a key (allow async construction) - * - search the process's keyrings - * - check the list of keys being created or updated - * - call out to userspace for a key if supplementary info was provided + * request_key_async - Request a key (allow async construction) + * @type: Type of key. + * @description: The searchable description of the key. + * @callout_info: The data to pass to the instantiation upcall (or NULL). + * @callout_len: The length of callout_info. + * + * As for request_key_and_link() except that it does not add the returned key + * to a keyring if found, new keys are always allocated in the user's quota and + * no auxiliary data can be passed. + * + * The caller should call wait_for_key_construction() to wait for the + * completion of the returned key if it is still undergoing construction. */ struct key *request_key_async(struct key_type *type, const char *description, @@ -620,9 +690,17 @@ EXPORT_SYMBOL(request_key_async); /* * request a key with auxiliary data for the upcaller (allow async construction) - * - search the process's keyrings - * - check the list of keys being created or updated - * - call out to userspace for a key if supplementary info was provided + * @type: Type of key. + * @description: The searchable description of the key. + * @callout_info: The data to pass to the instantiation upcall (or NULL). + * @callout_len: The length of callout_info. + * @aux: Auxiliary data for the upcall. + * + * As for request_key_and_link() except that it does not add the returned key + * to a keyring if found and new keys are always allocated in the user's quota. + * + * The caller should call wait_for_key_construction() to wait for the + * completion of the returned key if it is still undergoing construction. */ struct key *request_key_async_with_auxdata(struct key_type *type, const char *description, |