static void key_cleanup(struct work_struct *work);
static DECLARE_WORK(key_cleanup_task, key_cleanup);
-/* we serialise key instantiation and link */
+/* We serialise key instantiation and link */
DEFINE_MUTEX(key_construction_mutex);
-/* any key who's type gets unegistered will be re-typed to this */
+/* Any key who's type gets unegistered will be re-typed to this */
static struct key_type key_type_dead = {
.name = "dead",
};
#endif
/*
- * get the key quota record for a user, allocating a new record if one doesn't
- * already exist
+ * Get the key quota record for a user, allocating a new record if one doesn't
+ * already exist.
*/
struct key_user *key_user_lookup(uid_t uid, struct user_namespace *user_ns)
{
struct rb_node *parent = NULL;
struct rb_node **p;
- try_again:
+try_again:
p = &key_user_tree.rb_node;
spin_lock(&key_user_lock);
goto out;
/* okay - we found a user record for this UID */
- found:
+found:
atomic_inc(&user->usage);
spin_unlock(&key_user_lock);
kfree(candidate);
- out:
+out:
return user;
}
/*
- * dispose of a user structure
+ * Dispose of a user structure
*/
void key_user_put(struct key_user *user)
{
}
/*
- * assign a key the next unique serial number
- * - these are assigned randomly to avoid security issues through covert
- * channel problems
+ * Allocate a serial number for a key. These are assigned randomly to avoid
+ * security issues through covert channel problems.
*/
static inline void key_alloc_serial(struct key *key)
{
}
}
-/*
- * allocate a key of the specified type
- * - update the user's quota to reflect the existence of the key
- * - called from a key-type operation with key_types_sem read-locked by
- * key_create_or_update()
- * - this prevents unregistration of the key type
- * - upon return the key is as yet uninstantiated; the caller needs to either
- * instantiate the key or discard it before returning
+/**
+ * key_alloc - Allocate a key of the specified type.
+ * @type: The type of key to allocate.
+ * @desc: The key description to allow the key to be searched out.
+ * @uid: The owner of the new key.
+ * @gid: The group ID for the new key's group permissions.
+ * @cred: The credentials specifying UID namespace.
+ * @perm: The permissions mask of the new key.
+ * @flags: Flags specifying quota properties.
+ *
+ * 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 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
+ * quota is available, -EDQUOT will be returned.
+ *
+ * The LSM security modules can prevent a key being created, in which case
+ * -EACCES will be returned.
+ *
+ * Returns a pointer to the new key if successful and an error code otherwise.
+ *
+ * Note that the caller needs to ensure the key type isn't uninstantiated.
+ * Internally this can be done by locking key_types_sem. Externally, this can
+ * be done by either never unregistering the key type, or making sure
+ * key_alloc() calls don't race with module unloading.
*/
struct key *key_alloc(struct key_type *type, const char *desc,
uid_t uid, gid_t gid, const struct cred *cred,
key = ERR_PTR(-EDQUOT);
goto error;
}
-
EXPORT_SYMBOL(key_alloc);
-/*
- * reserve an amount of quota for the key's payload
+/**
+ * key_payload_reserve - Adjust data quota reservation for the key's payload
+ * @key: The key to make the reservation for.
+ * @datalen: The amount of data payload the caller now wants.
+ *
+ * Adjust the amount of the owning user's key data quota that a key reserves.
+ * If the amount is increased, then -EDQUOT may be returned if there isn't
+ * enough free quota available.
+ *
+ * If successful, 0 is returned.
*/
int key_payload_reserve(struct key *key, size_t datalen)
{
return ret;
}
-
EXPORT_SYMBOL(key_payload_reserve);
/*
- * instantiate a key and link it into the target keyring atomically
- * - called with the target keyring's semaphore writelocked
+ * Instantiate a key and link it into the target keyring atomically. Must be
+ * called with the target keyring's semaphore writelocked. The target key's
+ * semaphore need not be locked as instantiation is serialised by
+ * key_construction_mutex.
*/
static int __key_instantiate_and_link(struct key *key,
const void *data,
return ret;
}
-/*
- * instantiate a key and link it into the target keyring atomically
+/**
+ * key_instantiate_and_link - Instantiate a key and link it into the keyring.
+ * @key: The key to instantiate.
+ * @data: The data to use to instantiate the keyring.
+ * @datalen: The length of @data.
+ * @keyring: Keyring to create a link in on success (or NULL).
+ * @authkey: The authorisation token permitting instantiation.
+ *
+ * Instantiate a key that's in the uninstantiated state using the provided data
+ * and, if successful, link it in to the destination keyring if one is
+ * supplied.
+ *
+ * If successful, 0 is returned, the authorisation token is revoked and anyone
+ * waiting for the key is woken up. If the key was already instantiated,
+ * -EBUSY will be returned.
*/
int key_instantiate_and_link(struct key *key,
const void *data,
EXPORT_SYMBOL(key_instantiate_and_link);
-/*
- * negatively instantiate a key and link it into the target keyring atomically
+/**
+ * key_negate_and_link - Negatively instantiate a key and link it into the keyring.
+ * @key: The key to instantiate.
+ * @timeout: The timeout on the negative key.
+ * @keyring: Keyring to create a link in on success (or NULL).
+ * @authkey: The authorisation token permitting instantiation.
+ *
+ * Negatively instantiate a key that's in the uninstantiated state and, if
+ * successful, set its timeout and link it in to the destination keyring if one
+ * is supplied. The key and any links to the key will be automatically garbage
+ * collected after the timeout expires.
+ *
+ * Negative keys are used to rate limit repeated request_key() calls by causing
+ * them to return -ENOKEY until the negative key expires.
+ *
+ * If successful, 0 is returned, the authorisation token is revoked and anyone
+ * waiting for the key is woken up. If the key was already instantiated,
+ * -EBUSY will be returned.
*/
int key_negate_and_link(struct key *key,
unsigned timeout,
EXPORT_SYMBOL(key_negate_and_link);
/*
- * do cleaning up in process context so that we don't have to disable
- * interrupts all over the place
+ * Garbage collect keys in process context so that we don't have to disable
+ * interrupts all over the place.
+ *
+ * key_put() schedules this rather than trying to do the cleanup itself, which
+ * means key_put() doesn't have to sleep.
*/
static void key_cleanup(struct work_struct *work)
{
struct rb_node *_n;
struct key *key;
- go_again:
+go_again:
/* look for a dead key in the tree */
spin_lock(&key_serial_lock);
spin_unlock(&key_serial_lock);
return;
- found_dead_key:
+found_dead_key:
/* we found a dead key - once we've removed it from the tree, we can
* drop the lock */
rb_erase(&key->serial_node, &key_serial_tree);
goto go_again;
}
-/*
- * dispose of a reference to a key
- * - when all the references are gone, we schedule the cleanup task to come and
- * pull it out of the tree in definite process context
+/**
+ * key_put - Discard a reference to a key.
+ * @key: The key to discard a reference from.
+ *
+ * Discard a reference to a key, and when all the references are gone, we
+ * schedule the cleanup task to come and pull it out of the tree in process
+ * context at some later time.
*/
void key_put(struct key *key)
{
schedule_work(&key_cleanup_task);
}
}
-
EXPORT_SYMBOL(key_put);
/*
- * find a key by its serial number
+ * Find a key by its serial number.
*/
struct key *key_lookup(key_serial_t id)
{
goto found;
}
- not_found:
+not_found:
key = ERR_PTR(-ENOKEY);
goto error;
- found:
+found:
/* pretend it doesn't exist if it is awaiting deletion */
if (atomic_read(&key->usage) == 0)
goto not_found;
*/
atomic_inc(&key->usage);
- error:
+error:
spin_unlock(&key_serial_lock);
return key;
}
/*
- * find and lock the specified key type against removal
- * - we return with the sem readlocked
+ * Find and lock the specified key type against removal.
+ *
+ * We return with the sem read-locked if successful. If the type wasn't
+ * available -ENOKEY is returned instead.
*/
struct key_type *key_type_lookup(const char *type)
{
up_read(&key_types_sem);
ktype = ERR_PTR(-ENOKEY);
- found_kernel_type:
+found_kernel_type:
return ktype;
}
/*
- * unlock a key type
+ * Unlock a key type locked by key_type_lookup().
*/
void key_type_put(struct key_type *ktype)
{
}
/*
- * attempt to update an existing key
- * - the key has an incremented refcount
- * - we need to put the key if we get an error
+ * Attempt to update an existing key.
+ *
+ * The key is given to us with an incremented refcount that we need to discard
+ * if we get an error.
*/
static inline key_ref_t __key_update(key_ref_t key_ref,
const void *payload, size_t plen)
goto out;
}
-/*
- * search the specified keyring for a key of the same description; if one is
- * found, update it, otherwise add a new one
+/**
+ * key_create_or_update - Update or create and instantiate a key.
+ * @keyring_ref: A pointer to the destination keyring with possession flag.
+ * @type: The type of key.
+ * @description: The searchable description for the key.
+ * @payload: The data to use to instantiate or update the key.
+ * @plen: The length of @payload.
+ * @perm: The permissions mask for a new key.
+ * @flags: The quota flags for a new key.
+ *
+ * Search the destination keyring for a key of the same description and if one
+ * is found, update it, otherwise create and instantiate a new one and create a
+ * link to it from that keyring.
+ *
+ * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
+ * concocted.
+ *
+ * Returns a pointer to the new key if successful, -ENODEV if the key type
+ * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the
+ * caller isn't permitted to modify the keyring or the LSM did not permit
+ * creation of the key.
+ *
+ * On success, the possession flag from the keyring ref will be tacked on to
+ * the key ref before it is returned.
*/
key_ref_t key_create_or_update(key_ref_t keyring_ref,
const char *type,
key_ref = __key_update(key_ref, payload, plen);
goto error;
}
-
EXPORT_SYMBOL(key_create_or_update);
-/*
- * update a key
+/**
+ * key_update - Update a key's contents.
+ * @key_ref: The pointer (plus possession flag) to the key.
+ * @payload: The data to be used to update the key.
+ * @plen: The length of @payload.
+ *
+ * Attempt to update the contents of a key with the given payload data. The
+ * caller must be granted Write permission on the key. Negative keys can be
+ * instantiated by this method.
+ *
+ * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key
+ * type does not support updating. The key type may return other errors.
*/
int key_update(key_ref_t key_ref, const void *payload, size_t plen)
{
error:
return ret;
}
-
EXPORT_SYMBOL(key_update);
-/*
- * revoke a key
+/**
+ * key_revoke - Revoke a key.
+ * @key: The key to be revoked.
+ *
+ * Mark a key as being revoked and ask the type to free up its resources. The
+ * revocation timeout is set and the key and all its links will be
+ * automatically garbage collected after key_gc_delay amount of time if they
+ * are not manually dealt with first.
*/
void key_revoke(struct key *key)
{
up_write(&key->sem);
}
-
EXPORT_SYMBOL(key_revoke);
-/*
- * register a type of key
+/**
+ * register_key_type - Register a type of key.
+ * @ktype: The new key type.
+ *
+ * Register a new key type.
+ *
+ * Returns 0 on success or -EEXIST if a type of this name already exists.
*/
int register_key_type(struct key_type *ktype)
{
list_add(&ktype->link, &key_types_list);
ret = 0;
- out:
+out:
up_write(&key_types_sem);
return ret;
}
-
EXPORT_SYMBOL(register_key_type);
-/*
- * unregister a type of key
+/**
+ * unregister_key_type - Unregister a type of key.
+ * @ktype: The key type.
+ *
+ * Unregister a key type and mark all the extant keys of this type as dead.
+ * Those keys of this type are then destroyed to get rid of their payloads and
+ * they and their links will be garbage collected as soon as possible.
*/
void unregister_key_type(struct key_type *ktype)
{
key_schedule_gc(0);
}
-
EXPORT_SYMBOL(unregister_key_type);
/*
- * initialise the key management stuff
+ * Initialise the key management state.
*/
void __init key_init(void)
{
projects / deliverable / linux.git / blobdiff