(keyring)->payload.subscriptions, \
rwsem_is_locked((struct rw_semaphore *)&(keyring)->sem)))
+#define KEY_LINK_FIXQUOTA 1UL
+
/*
- * when plumbing the depths of the key tree, this sets a hard limit set on how
- * deep we're willing to go
+ * When plumbing the depths of the key tree, this sets a hard limit
+ * set on how deep we're willing to go.
*/
#define KEYRING_SEARCH_MAX_DEPTH 6
/*
- * we keep all named keyrings in a hash to speed looking them up
+ * We keep all named keyrings in a hash to speed looking them up.
*/
#define KEYRING_NAME_HASH_SIZE (1 << 5)
}
/*
- * the keyring type definition
+ * The keyring key type definition. Keyrings are simply keys of this type and
+ * can be treated as ordinary keys in addition to having their own special
+ * operations.
*/
static int keyring_instantiate(struct key *keyring,
const void *data, size_t datalen);
.describe = keyring_describe,
.read = keyring_read,
};
-
EXPORT_SYMBOL(key_type_keyring);
/*
- * semaphore to serialise link/link calls to prevent two link calls in parallel
- * introducing a cycle
+ * Semaphore to serialise link/link calls to prevent two link calls in parallel
+ * introducing a cycle.
*/
static DECLARE_RWSEM(keyring_serialise_link_sem);
-/*****************************************************************************/
/*
- * publish the name of a keyring so that it can be found by name (if it has
- * one)
+ * Publish the name of a keyring so that it can be found by name (if it has
+ * one).
*/
static void keyring_publish_name(struct key *keyring)
{
write_unlock(&keyring_name_lock);
}
+}
-} /* end keyring_publish_name() */
-
-/*****************************************************************************/
/*
- * initialise a keyring
- * - we object if we were given any data
+ * Initialise a keyring.
+ *
+ * Returns 0 on success, -EINVAL if given any data.
*/
static int keyring_instantiate(struct key *keyring,
const void *data, size_t datalen)
}
return ret;
+}
-} /* end keyring_instantiate() */
-
-/*****************************************************************************/
/*
- * match keyrings on their name
+ * Match keyrings on their name
*/
static int keyring_match(const struct key *keyring, const void *description)
{
return keyring->description &&
strcmp(keyring->description, description) == 0;
+}
-} /* end keyring_match() */
-
-/*****************************************************************************/
/*
- * dispose of the data dangling from the corpse of a keyring
+ * Clean up a keyring when it is destroyed. Unpublish its name if it had one
+ * and dispose of its data.
*/
static void keyring_destroy(struct key *keyring)
{
key_put(klist->keys[loop]);
kfree(klist);
}
+}
-} /* end keyring_destroy() */
-
-/*****************************************************************************/
/*
- * describe the keyring
+ * Describe a keyring for /proc.
*/
static void keyring_describe(const struct key *keyring, struct seq_file *m)
{
else
seq_puts(m, ": empty");
rcu_read_unlock();
+}
-} /* end keyring_describe() */
-
-/*****************************************************************************/
/*
- * read a list of key IDs from the keyring's contents
- * - the keyring's semaphore is read-locked
+ * Read a list of key IDs from the keyring's contents in binary form
+ *
+ * The keyring's semaphore is read-locked by the caller.
*/
static long keyring_read(const struct key *keyring,
char __user *buffer, size_t buflen)
error:
return ret;
+}
-} /* end keyring_read() */
-
-/*****************************************************************************/
/*
- * allocate a keyring and link into the destination keyring
+ * Allocate a keyring and link into the destination keyring.
*/
struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
const struct cred *cred, unsigned long flags,
}
return keyring;
+}
-} /* end keyring_alloc() */
-
-/*****************************************************************************/
-/*
- * search the supplied keyring tree for a key that matches the criterion
- * - perform a breadth-then-depth search up to the prescribed limit
- * - we only find keys on which we have search permission
- * - we use the supplied match function to see if the description (or other
- * feature of interest) matches
- * - we rely on RCU to prevent the keyring lists from disappearing on us
- * - we return -EAGAIN if we didn't find any matching key
- * - we return -ENOKEY if we only found negative matching keys
- * - we propagate the possession attribute from the keyring ref to the key ref
+/**
+ * keyring_search_aux - Search a keyring tree for a key matching some criteria
+ * @keyring_ref: A pointer to the keyring with possession indicator.
+ * @cred: The credentials to use for permissions checks.
+ * @type: The type of key to search for.
+ * @description: Parameter for @match.
+ * @match: Function to rule on whether or not a key is the one required.
+ *
+ * Search the supplied keyring tree for a key that matches the criteria given.
+ * The root keyring and any linked keyrings must grant Search permission to the
+ * caller to be searchable and keys can only be found if they too grant Search
+ * to the caller. The possession flag on the root keyring pointer controls use
+ * of the possessor bits in permissions checking of the entire tree. In
+ * addition, the LSM gets to forbid keyring searches and key matches.
+ *
+ * The search is performed as a breadth-then-depth search up to the prescribed
+ * limit (KEYRING_SEARCH_MAX_DEPTH).
+ *
+ * Keys are matched to the type provided and are then filtered by the match
+ * function, which is given the description to use in any way it sees fit. The
+ * match function may use any attributes of a key that it wishes to to
+ * determine the match. Normally the match function from the key type would be
+ * used.
+ *
+ * RCU is used to prevent the keyring key lists from disappearing without the
+ * need to take lots of locks.
+ *
+ * Returns a pointer to the found key and increments the key usage count if
+ * successful; -EAGAIN if no matching keys were found, or if expired or revoked
+ * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the
+ * specified keyring wasn't a keyring.
+ *
+ * In the case of a successful return, the possession attribute from
+ * @keyring_ref is propagated to the returned key reference.
*/
key_ref_t keyring_search_aux(key_ref_t keyring_ref,
const struct cred *cred,
rcu_read_unlock();
error:
return key_ref;
+}
-} /* end keyring_search_aux() */
-
-/*****************************************************************************/
-/*
- * search the supplied keyring tree for a key that matches the criterion
- * - perform a breadth-then-depth search up to the prescribed limit
- * - we only find keys on which we have search permission
- * - we readlock the keyrings as we search down the tree
- * - we return -EAGAIN if we didn't find any matching key
- * - we return -ENOKEY if we only found negative matching keys
+/**
+ * keyring_search - Search the supplied keyring tree for a matching key
+ * @keyring: The root of the keyring tree to be searched.
+ * @type: The type of keyring we want to find.
+ * @description: The name of the keyring we want to find.
+ *
+ * As keyring_search_aux() above, but using the current task's credentials and
+ * type's default matching function.
*/
key_ref_t keyring_search(key_ref_t keyring,
struct key_type *type,
return keyring_search_aux(keyring, current->cred,
type, description, type->match);
-
-} /* end keyring_search() */
-
+}
EXPORT_SYMBOL(keyring_search);
-/*****************************************************************************/
/*
- * search the given keyring only (no recursion)
- * - keyring must be locked by caller
- * - caller must guarantee that the keyring is a keyring
+ * Search the given keyring only (no recursion).
+ *
+ * The caller must guarantee that the keyring is a keyring and that the
+ * permission is granted to search the keyring as no check is made here.
+ *
+ * RCU is used to make it unnecessary to lock the keyring key list here.
+ *
+ * Returns a pointer to the found key with usage count incremented if
+ * successful and returns -ENOKEY if not found. Revoked keys and keys not
+ * providing the requested permission are skipped over.
+ *
+ * If successful, the possession indicator is propagated from the keyring ref
+ * to the returned key reference.
*/
key_ref_t __keyring_search_one(key_ref_t keyring_ref,
const struct key_type *ktype,
atomic_inc(&key->usage);
rcu_read_unlock();
return make_key_ref(key, possessed);
+}
-} /* end __keyring_search_one() */
-
-/*****************************************************************************/
/*
- * find a keyring with the specified name
- * - all named keyrings are searched
- * - normally only finds keyrings with search permission for the current process
+ * Find a keyring with the specified name.
+ *
+ * All named keyrings in the current user namespace are searched, provided they
+ * grant Search permission directly to the caller (unless this check is
+ * skipped). Keyrings whose usage points have reached zero or who have been
+ * revoked are skipped.
+ *
+ * Returns a pointer to the keyring with the keyring's refcount having being
+ * incremented on success. -ENOKEY is returned if a key could not be found.
*/
struct key *find_keyring_by_name(const char *name, bool skip_perm_check)
{
out:
read_unlock(&keyring_name_lock);
return keyring;
+}
-} /* end find_keyring_by_name() */
-
-/*****************************************************************************/
/*
- * see if a cycle will will be created by inserting acyclic tree B in acyclic
- * tree A at the topmost level (ie: as a direct child of A)
- * - since we are adding B to A at the top level, checking for cycles should
- * just be a matter of seeing if node A is somewhere in tree B
+ * See if a cycle will will be created by inserting acyclic tree B in acyclic
+ * tree A at the topmost level (ie: as a direct child of A).
+ *
+ * Since we are adding B to A at the top level, checking for cycles should just
+ * be a matter of seeing if node A is somewhere in tree B.
*/
static int keyring_detect_cycle(struct key *A, struct key *B)
{
cycle_detected:
ret = -EDEADLK;
goto error;
-
-} /* end keyring_detect_cycle() */
+}
/*
- * dispose of a keyring list after the RCU grace period, freeing the unlinked
+ * Dispose of a keyring list after the RCU grace period, freeing the unlinked
* key
*/
static void keyring_unlink_rcu_disposal(struct rcu_head *rcu)
struct keyring_list *klist =
container_of(rcu, struct keyring_list, rcu);
- if (klist->delkey != USHORT_MAX)
+ if (klist->delkey != USHRT_MAX)
key_put(klist->keys[klist->delkey]);
kfree(klist);
}
/*
- * preallocate memory so that a key can be linked into to a keyring
+ * Preallocate memory so that a key can be linked into to a keyring.
*/
int __key_link_begin(struct key *keyring, const struct key_type *type,
- const char *description,
- struct keyring_list **_prealloc)
+ const char *description, unsigned long *_prealloc)
__acquires(&keyring->sem)
{
struct keyring_list *klist, *nklist;
+ unsigned long prealloc;
unsigned max;
size_t size;
int loop, ret;
/* note replacement slot */
klist->delkey = nklist->delkey = loop;
+ prealloc = (unsigned long)nklist;
goto done;
}
}
if (klist && klist->nkeys < klist->maxkeys) {
/* there's sufficient slack space to append directly */
nklist = NULL;
+ prealloc = KEY_LINK_FIXQUOTA;
} else {
/* grow the key list */
max = 4;
max += klist->maxkeys;
ret = -ENFILE;
- if (max > USHORT_MAX - 1)
+ if (max > USHRT_MAX - 1)
goto error_quota;
size = sizeof(*klist) + sizeof(struct key *) * max;
if (size > PAGE_SIZE)
sizeof(struct key *) * klist->nkeys);
nklist->delkey = klist->nkeys;
nklist->nkeys = klist->nkeys + 1;
- klist->delkey = USHORT_MAX;
+ klist->delkey = USHRT_MAX;
} else {
nklist->nkeys = 1;
nklist->delkey = 0;
nklist->keys[nklist->delkey] = NULL;
}
+ prealloc = (unsigned long)nklist | KEY_LINK_FIXQUOTA;
done:
- *_prealloc = nklist;
+ *_prealloc = prealloc;
kleave(" = 0");
return 0;
}
/*
- * check already instantiated keys aren't going to be a problem
- * - the caller must have called __key_link_begin()
- * - don't need to call this for keys that were created since __key_link_begin()
- * was called
+ * Check already instantiated keys aren't going to be a problem.
+ *
+ * The caller must have called __key_link_begin(). Don't need to call this for
+ * keys that were created since __key_link_begin() was called.
*/
int __key_link_check_live_key(struct key *keyring, struct key *key)
{
}
/*
- * link a key into to a keyring
- * - must be called with __key_link_begin() having being called
- * - discard already extant link to matching key if there is one
+ * Link a key into to a keyring.
+ *
+ * Must be called with __key_link_begin() having being called. Discards any
+ * already extant link to matching key if there is one, so that each keyring
+ * holds at most one link to any given key of a particular type+description
+ * combination.
*/
void __key_link(struct key *keyring, struct key *key,
- struct keyring_list **_prealloc)
+ unsigned long *_prealloc)
{
struct keyring_list *klist, *nklist;
- nklist = *_prealloc;
- *_prealloc = NULL;
+ nklist = (struct keyring_list *)(*_prealloc & ~KEY_LINK_FIXQUOTA);
+ *_prealloc = 0;
kenter("%d,%d,%p", keyring->serial, key->serial, nklist);
}
/*
- * finish linking a key into to a keyring
- * - must be called with __key_link_begin() having being called
+ * Finish linking a key into to a keyring.
+ *
+ * Must be called with __key_link_begin() having being called.
*/
void __key_link_end(struct key *keyring, struct key_type *type,
- struct keyring_list *prealloc)
+ unsigned long prealloc)
__releases(&keyring->sem)
{
BUG_ON(type == NULL);
BUG_ON(type->name == NULL);
- kenter("%d,%s,%p", keyring->serial, type->name, prealloc);
+ kenter("%d,%s,%lx", keyring->serial, type->name, prealloc);
if (type == &key_type_keyring)
up_write(&keyring_serialise_link_sem);
if (prealloc) {
- kfree(prealloc);
- key_payload_reserve(keyring,
- keyring->datalen - KEYQUOTA_LINK_BYTES);
+ if (prealloc & KEY_LINK_FIXQUOTA)
+ key_payload_reserve(keyring,
+ keyring->datalen -
+ KEYQUOTA_LINK_BYTES);
+ kfree((struct keyring_list *)(prealloc & ~KEY_LINK_FIXQUOTA));
}
up_write(&keyring->sem);
}
-/*
- * link a key to a keyring
+/**
+ * key_link - Link a key to a keyring
+ * @keyring: The keyring to make the link in.
+ * @key: The key to link to.
+ *
+ * Make a link in a keyring to a key, such that the keyring holds a reference
+ * on that key and the key can potentially be found by searching that keyring.
+ *
+ * This function will write-lock the keyring's semaphore and will consume some
+ * of the user's key data quota to hold the link.
+ *
+ * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring,
+ * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is
+ * full, -EDQUOT if there is insufficient key data quota remaining to add
+ * another link or -ENOMEM if there's insufficient memory.
+ *
+ * It is assumed that the caller has checked that it is permitted for a link to
+ * be made (the keyring should have Write permission and the key Link
+ * permission).
*/
int key_link(struct key *keyring, struct key *key)
{
- struct keyring_list *prealloc;
+ unsigned long prealloc;
int ret;
key_check(keyring);
return ret;
}
-
EXPORT_SYMBOL(key_link);
-/*****************************************************************************/
-/*
- * unlink the first link to a key from a keyring
+/**
+ * key_unlink - Unlink the first link to a key from a keyring.
+ * @keyring: The keyring to remove the link from.
+ * @key: The key the link is to.
+ *
+ * Remove a link from a keyring to a key.
+ *
+ * This function will write-lock the keyring's semaphore.
+ *
+ * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if
+ * the key isn't linked to by the keyring or -ENOMEM if there's insufficient
+ * memory.
+ *
+ * It is assumed that the caller has checked that it is permitted for a link to
+ * be removed (the keyring should have Write permission; no permissions are
+ * required on the key).
*/
int key_unlink(struct key *keyring, struct key *key)
{
ret = -ENOMEM;
up_write(&keyring->sem);
goto error;
-
-} /* end key_unlink() */
-
+}
EXPORT_SYMBOL(key_unlink);
-/*****************************************************************************/
/*
- * dispose of a keyring list after the RCU grace period, releasing the keys it
- * links to
+ * Dispose of a keyring list after the RCU grace period, releasing the keys it
+ * links to.
*/
static void keyring_clear_rcu_disposal(struct rcu_head *rcu)
{
key_put(klist->keys[loop]);
kfree(klist);
+}
-} /* end keyring_clear_rcu_disposal() */
-
-/*****************************************************************************/
-/*
- * clear the specified process keyring
- * - implements keyctl(KEYCTL_CLEAR)
+/**
+ * keyring_clear - Clear a keyring
+ * @keyring: The keyring to clear.
+ *
+ * Clear the contents of the specified keyring.
+ *
+ * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring.
*/
int keyring_clear(struct key *keyring)
{
}
return ret;
-
-} /* end keyring_clear() */
-
+}
EXPORT_SYMBOL(keyring_clear);
-/*****************************************************************************/
/*
- * dispose of the links from a revoked keyring
- * - called with the key sem write-locked
+ * Dispose of the links from a revoked keyring.
+ *
+ * This is called with the key sem write-locked.
*/
static void keyring_revoke(struct key *keyring)
{
rcu_assign_pointer(keyring->payload.subscriptions, NULL);
call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
}
-
-} /* end keyring_revoke() */
+}
/*
- * Determine whether a key is dead
+ * Determine whether a key is dead.
*/
static bool key_is_dead(struct key *key, time_t limit)
{
}
/*
- * Collect garbage from the contents of a keyring
+ * Collect garbage from the contents of a keyring, replacing the old list with
+ * a new one with the pointers all shuffled down.
+ *
+ * Dead keys are classed as oned that are flagged as being dead or are revoked,
+ * expired or negative keys that were revoked or expired before the specified
+ * limit.
*/
void keyring_gc(struct key *keyring, time_t limit)
{
projects / linux-flexiantxendom0-natty.git / blobdiff