-/* keyring.c: keyring handling
+/* Keyring handling
*
- * Copyright (C) 2004-5 Red Hat, Inc. All Rights Reserved.
+ * Copyright (C) 2004-2005, 2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/slab.h>
+#include <linux/security.h>
#include <linux/seq_file.h>
#include <linux/err.h>
-#include <asm/uaccess.h>
+#include <keys/keyring-type.h>
+#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)))
+
+#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)
unsigned bucket = 0;
for (; *desc; desc++)
- bucket += (unsigned char) *desc;
+ bucket += (unsigned char)*desc;
return bucket & (KEYRING_NAME_HASH_SIZE - 1);
}
/*
- * 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);
-static int keyring_duplicate(struct key *keyring, const struct key *source);
static int keyring_match(const struct key *keyring, const void *criterion);
+static void keyring_revoke(struct key *keyring);
static void keyring_destroy(struct key *keyring);
static void keyring_describe(const struct key *keyring, struct seq_file *m);
static long keyring_read(const struct key *keyring,
.name = "keyring",
.def_datalen = sizeof(struct keyring_list),
.instantiate = keyring_instantiate,
- .duplicate = keyring_duplicate,
.match = keyring_match,
+ .revoke = keyring_revoke,
.destroy = keyring_destroy,
.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.
*/
-DECLARE_RWSEM(keyring_serialise_link_sem);
+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).
*/
-void keyring_publish_name(struct key *keyring)
+static void keyring_publish_name(struct key *keyring)
{
int bucket;
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() */
-
-/*****************************************************************************/
-/*
- * duplicate the list of subscribed keys from a source keyring into this one
- */
-static int keyring_duplicate(struct key *keyring, const struct key *source)
-{
- struct keyring_list *sklist, *klist;
- unsigned max;
- size_t size;
- int loop, ret;
-
- const unsigned limit =
- (PAGE_SIZE - sizeof(*klist)) / sizeof(struct key *);
-
- ret = 0;
-
- /* find out how many keys are currently linked */
- rcu_read_lock();
- sklist = rcu_dereference(source->payload.subscriptions);
- max = 0;
- if (sklist)
- max = sklist->nkeys;
- rcu_read_unlock();
-
- /* allocate a new payload and stuff load with key links */
- if (max > 0) {
- BUG_ON(max > limit);
-
- max = (max + 3) & ~3;
- if (max > limit)
- max = limit;
-
- ret = -ENOMEM;
- size = sizeof(*klist) + sizeof(struct key *) * max;
- klist = kmalloc(size, GFP_KERNEL);
- if (!klist)
- goto error;
-
- /* set links */
- rcu_read_lock();
- sklist = rcu_dereference(source->payload.subscriptions);
-
- klist->maxkeys = max;
- klist->nkeys = sklist->nkeys;
- memcpy(klist->keys,
- sklist->keys,
- sklist->nkeys * sizeof(struct key *));
-
- for (loop = klist->nkeys - 1; loop >= 0; loop--)
- atomic_inc(&klist->keys[loop]->usage);
-
- rcu_read_unlock();
-
- rcu_assign_pointer(keyring->payload.subscriptions, klist);
- ret = 0;
- }
-
- error:
- return ret;
-
-} /* end keyring_duplicate() */
-
-/*****************************************************************************/
/*
- * 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)
{
write_unlock(&keyring_name_lock);
}
- klist = rcu_dereference(keyring->payload.subscriptions);
+ klist = rcu_dereference_check(keyring->payload.subscriptions,
+ rcu_read_lock_held() ||
+ atomic_read(&keyring->usage) == 0);
if (klist) {
for (loop = klist->nkeys - 1; loop >= 0; loop--)
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)
{
struct keyring_list *klist;
- if (keyring->description) {
+ if (keyring->description)
seq_puts(m, keyring->description);
- }
- else {
- seq_puts(m, "[anon]");
- }
-
- rcu_read_lock();
- klist = rcu_dereference(keyring->payload.subscriptions);
- if (klist)
- seq_printf(m, ": %u/%u", klist->nkeys, klist->maxkeys);
else
- seq_puts(m, ": empty");
- rcu_read_unlock();
+ seq_puts(m, "[anon]");
-} /* end keyring_describe() */
+ if (key_is_instantiated(keyring)) {
+ rcu_read_lock();
+ klist = rcu_dereference(keyring->payload.subscriptions);
+ if (klist)
+ seq_printf(m, ": %u/%u", klist->nkeys, klist->maxkeys);
+ else
+ seq_puts(m, ": empty");
+ rcu_read_unlock();
+ }
+}
-/*****************************************************************************/
/*
- * 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)
int loop, ret;
ret = 0;
- klist = rcu_dereference(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);
ret = qty;
}
- error:
+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,
- int not_in_quota, struct key *dest)
+ const struct cred *cred, unsigned long flags,
+ struct key *dest)
{
struct key *keyring;
int ret;
keyring = key_alloc(&key_type_keyring, description,
- uid, gid, KEY_POS_ALL | KEY_USR_ALL, not_in_quota);
+ uid, gid, cred,
+ (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL,
+ flags);
if (!IS_ERR(keyring)) {
ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
}
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.
+ * @no_state_check: Don't check if a matching key is bad
+ *
+ * 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,
- struct task_struct *context,
+ const struct cred *cred,
struct key_type *type,
const void *description,
- key_match_func_t match)
+ key_match_func_t match,
+ bool no_state_check)
{
struct {
struct keyring_list *keylist;
struct keyring_list *keylist;
struct timespec now;
- unsigned long possessed;
+ unsigned long possessed, kflags;
struct key *keyring, *key;
key_ref_t key_ref;
long err;
key_check(keyring);
/* top keyring must have search permission to begin the search */
- key_ref = ERR_PTR(-EACCES);
- if (!key_task_permission(keyring_ref, context, KEY_SEARCH))
+ err = key_task_permission(keyring_ref, cred, KEY_SEARCH);
+ if (err < 0) {
+ key_ref = ERR_PTR(err);
goto error;
+ }
key_ref = ERR_PTR(-ENOTDIR);
if (keyring->type != &key_type_keyring)
err = -EAGAIN;
sp = 0;
+ /* firstly we should check to see if this top-level keyring is what we
+ * are looking for */
+ key_ref = ERR_PTR(-EAGAIN);
+ kflags = keyring->flags;
+ if (keyring->type == type && match(keyring, description)) {
+ key = keyring;
+ if (no_state_check)
+ goto found;
+
+ /* check it isn't negative and hasn't expired or been
+ * revoked */
+ if (kflags & (1 << KEY_FLAG_REVOKED))
+ goto error_2;
+ if (key->expiry && now.tv_sec >= key->expiry)
+ goto error_2;
+ key_ref = ERR_PTR(key->type_data.reject_error);
+ if (kflags & (1 << KEY_FLAG_NEGATIVE))
+ goto error_2;
+ goto found;
+ }
+
+ /* otherwise, the top keyring must not be revoked, expired, or
+ * negatively instantiated if we are to search it */
+ key_ref = ERR_PTR(-EAGAIN);
+ if (kflags & ((1 << KEY_FLAG_REVOKED) | (1 << KEY_FLAG_NEGATIVE)) ||
+ (keyring->expiry && now.tv_sec >= keyring->expiry))
+ goto error_2;
+
/* start processing a new keyring */
descend:
if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
/* iterate through the keys in this keyring first */
for (kix = 0; kix < keylist->nkeys; kix++) {
key = keylist->keys[kix];
+ kflags = key->flags;
/* ignore keys not of this type */
if (key->type != type)
continue;
/* skip revoked keys and expired keys */
- if (test_bit(KEY_FLAG_REVOKED, &key->flags))
- continue;
+ if (!no_state_check) {
+ if (kflags & (1 << KEY_FLAG_REVOKED))
+ continue;
- if (key->expiry && now.tv_sec >= key->expiry)
- continue;
+ if (key->expiry && now.tv_sec >= key->expiry)
+ continue;
+ }
/* keys that don't match */
if (!match(key, description))
continue;
/* key must have search permissions */
- if (!key_task_permission(make_key_ref(key, possessed),
- context, KEY_SEARCH))
+ if (key_task_permission(make_key_ref(key, possessed),
+ cred, KEY_SEARCH) < 0)
continue;
- /* we set a different error code if we find a negative key */
- if (test_bit(KEY_FLAG_NEGATIVE, &key->flags)) {
- err = -ENOKEY;
+ if (no_state_check)
+ goto found;
+
+ /* we set a different error code if we pass a negative key */
+ if (kflags & (1 << KEY_FLAG_NEGATIVE)) {
+ err = key->type_data.reject_error;
continue;
}
if (sp >= KEYRING_SEARCH_MAX_DEPTH)
continue;
- if (!key_task_permission(make_key_ref(key, possessed),
- context, KEY_SEARCH))
+ if (key_task_permission(make_key_ref(key, possessed),
+ cred, KEY_SEARCH) < 0)
continue;
/* stack the current position */
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,
if (!type->match)
return ERR_PTR(-ENOKEY);
- return keyring_search_aux(keyring, current,
- type, description, type->match);
-
-} /* end keyring_search() */
-
+ return keyring_search_aux(keyring, current->cred,
+ type, description, type->match, false);
+}
EXPORT_SYMBOL(keyring_search);
-/*****************************************************************************/
/*
- * search the given keyring only (no recursion)
- * - keyring must be locked by caller
+ * 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,
(!key->type->match ||
key->type->match(key, description)) &&
key_permission(make_key_ref(key, possessed),
- perm) &&
+ perm) == 0 &&
!test_bit(KEY_FLAG_REVOKED, &key->flags)
)
goto found;
rcu_read_unlock();
return ERR_PTR(-ENOKEY);
- found:
+found:
atomic_inc(&key->usage);
rcu_read_unlock();
return make_key_ref(key, possessed);
+}
-} /* end __keyring_search_one() */
-
-/*****************************************************************************/
-/*
- * search for an instantiation authorisation key matching a target key
- * - the RCU read lock must be held by the caller
- * - a target_id of zero specifies any valid token
- */
-struct key *keyring_search_instkey(struct key *keyring,
- key_serial_t target_id)
-{
- struct request_key_auth *rka;
- struct keyring_list *klist;
- struct key *instkey;
- int loop;
-
- klist = rcu_dereference(keyring->payload.subscriptions);
- if (klist) {
- for (loop = 0; loop < klist->nkeys; loop++) {
- instkey = klist->keys[loop];
-
- if (instkey->type != &key_type_request_key_auth)
- continue;
-
- rka = instkey->payload.data;
- if (target_id && rka->target_key->serial != target_id)
- continue;
-
- /* the auth key is revoked during instantiation */
- if (!test_bit(KEY_FLAG_REVOKED, &instkey->flags))
- goto found;
-
- instkey = ERR_PTR(-EKEYREVOKED);
- goto error;
- }
- }
-
- instkey = ERR_PTR(-EACCES);
- goto error;
-
-found:
- atomic_inc(&instkey->usage);
-error:
- return instkey;
-
-} /* end keyring_search_instkey() */
-
-/*****************************************************************************/
/*
- * find a keyring with the specified name
- * - all named keyrings are searched
- * - only find keyrings with search permission for the process
- * - only find keyrings with a serial number greater than the one specified
+ * 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, key_serial_t bound)
+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);
&keyring_name_hash[bucket],
type_data.link
) {
+ if (keyring->user->user_ns != current_user_ns())
+ continue;
+
if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
continue;
if (strcmp(keyring->description, name) != 0)
continue;
- if (!key_permission(make_key_ref(keyring, 0),
- KEY_SEARCH))
+ if (!skip_perm_check &&
+ key_permission(make_key_ref(keyring, 0),
+ KEY_SEARCH) < 0)
continue;
- /* found a potential candidate, but we still need to
- * check the serial number */
- if (keyring->serial <= bound)
+ /* 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;
-
- /* we've got a match */
- atomic_inc(&keyring->usage);
- read_unlock(&keyring_name_lock);
- goto error;
+ 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() */
-
-/*****************************************************************************/
/*
- * 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)
{
sp = 0;
/* start processing a new keyring */
- descend:
+descend:
if (test_bit(KEY_FLAG_REVOKED, &subtree->flags))
goto not_this_keyring;
goto not_this_keyring;
kix = 0;
- ascend:
+ascend:
/* iterate through the remaining keys in this keyring */
for (; kix < keylist->nkeys; kix++) {
key = keylist->keys[kix];
/* the keyring we're looking at was disqualified or didn't contain a
* matching key */
- not_this_keyring:
+not_this_keyring:
if (sp > 0) {
/* resume the checking of a keyring higher up in the tree */
sp--;
ret = 0; /* no cycles detected */
- error:
+error:
rcu_read_unlock();
return ret;
- too_deep:
+too_deep:
ret = -ELOOP;
goto error;
- cycle_detected:
+cycle_detected:
ret = -EDEADLK;
goto error;
+}
-} /* end keyring_detect_cycle() */
-
-/*****************************************************************************/
/*
- * dispose of a keyring list after the RCU grace period
+ * Dispose of a keyring list after the RCU grace period, freeing the unlinked
+ * key
*/
-static void keyring_link_rcu_disposal(struct rcu_head *rcu)
+static void keyring_unlink_rcu_disposal(struct rcu_head *rcu)
{
struct keyring_list *klist =
container_of(rcu, struct keyring_list, rcu);
+ if (klist->delkey != USHRT_MAX)
+ key_put(klist->keys[klist->delkey]);
kfree(klist);
+}
-} /* end keyring_link_rcu_disposal() */
-
-/*****************************************************************************/
/*
- * link a key into to a keyring
- * - must be called with the keyring's semaphore write-locked
+ * Preallocate memory so that a key can be linked into to a keyring.
*/
-int __key_link(struct key *keyring, struct key *key)
+int __key_link_begin(struct key *keyring, const struct key_type *type,
+ const char *description, unsigned long *_prealloc)
+ __acquires(&keyring->sem)
{
struct keyring_list *klist, *nklist;
+ unsigned long prealloc;
unsigned max;
size_t size;
- int ret;
+ int loop, ret;
- ret = -EKEYREVOKED;
- if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
- goto error;
+ kenter("%d,%s,%s,", key_serial(keyring), type->name, description);
- ret = -ENOTDIR;
if (keyring->type != &key_type_keyring)
- goto error;
+ return -ENOTDIR;
- /* serialise link/link calls to prevent parallel calls causing a
- * cycle when applied to two keyring in opposite orders */
- down_write(&keyring_serialise_link_sem);
+ down_write(&keyring->sem);
- /* check that we aren't going to create a cycle adding one keyring to
- * another */
- if (key->type == &key_type_keyring) {
- ret = keyring_detect_cycle(keyring, key);
- if (ret < 0)
- goto error2;
+ ret = -EKEYREVOKED;
+ if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
+ goto error_krsem;
+
+ /* serialise link/link calls to prevent parallel calls causing a cycle
+ * when linking two keyring in opposite orders */
+ if (type == &key_type_keyring)
+ down_write(&keyring_serialise_link_sem);
+
+ klist = rcu_dereference_locked_keyring(keyring);
+
+ /* see if there's a matching key we can displace */
+ if (klist && klist->nkeys > 0) {
+ for (loop = klist->nkeys - 1; loop >= 0; loop--) {
+ if (klist->keys[loop]->type == type &&
+ strcmp(klist->keys[loop]->description,
+ description) == 0
+ ) {
+ /* found a match - we'll replace this one with
+ * the new key */
+ size = sizeof(struct key *) * klist->maxkeys;
+ size += sizeof(*klist);
+ BUG_ON(size > PAGE_SIZE);
+
+ ret = -ENOMEM;
+ nklist = kmemdup(klist, size, GFP_KERNEL);
+ if (!nklist)
+ goto error_sem;
+
+ /* note replacement slot */
+ klist->delkey = nklist->delkey = loop;
+ prealloc = (unsigned long)nklist;
+ goto done;
+ }
+ }
}
/* check that we aren't going to overrun the user's quota */
ret = key_payload_reserve(keyring,
keyring->datalen + KEYQUOTA_LINK_BYTES);
if (ret < 0)
- goto error2;
-
- klist = keyring->payload.subscriptions;
+ goto error_sem;
if (klist && klist->nkeys < klist->maxkeys) {
- /* there's sufficient slack space to add directly */
- atomic_inc(&key->usage);
-
- klist->keys[klist->nkeys] = key;
- smp_wmb();
- klist->nkeys++;
- smp_wmb();
-
- ret = 0;
- }
- else {
+ /* there's sufficient slack space to append directly */
+ nklist = NULL;
+ prealloc = KEY_LINK_FIXQUOTA;
+ } else {
/* grow the key list */
max = 4;
if (klist)
max += klist->maxkeys;
ret = -ENFILE;
- if (max > 65535)
- goto error3;
+ if (max > USHRT_MAX - 1)
+ goto error_quota;
size = sizeof(*klist) + sizeof(struct key *) * max;
if (size > PAGE_SIZE)
- goto error3;
+ goto error_quota;
ret = -ENOMEM;
nklist = kmalloc(size, GFP_KERNEL);
if (!nklist)
- goto error3;
- nklist->maxkeys = max;
- nklist->nkeys = 0;
+ goto error_quota;
+ nklist->maxkeys = max;
if (klist) {
- nklist->nkeys = klist->nkeys;
- memcpy(nklist->keys,
- klist->keys,
+ memcpy(nklist->keys, klist->keys,
sizeof(struct key *) * klist->nkeys);
+ nklist->delkey = klist->nkeys;
+ nklist->nkeys = klist->nkeys + 1;
+ klist->delkey = USHRT_MAX;
+ } else {
+ nklist->nkeys = 1;
+ nklist->delkey = 0;
}
/* add the key into the new space */
- atomic_inc(&key->usage);
- nklist->keys[nklist->nkeys++] = key;
-
- rcu_assign_pointer(keyring->payload.subscriptions, nklist);
-
- /* dispose of the old keyring list */
- if (klist)
- call_rcu(&klist->rcu, keyring_link_rcu_disposal);
-
- ret = 0;
+ nklist->keys[nklist->delkey] = NULL;
}
- error2:
- up_write(&keyring_serialise_link_sem);
- error:
- return ret;
+ prealloc = (unsigned long)nklist | KEY_LINK_FIXQUOTA;
+done:
+ *_prealloc = prealloc;
+ kleave(" = 0");
+ return 0;
- error3:
+error_quota:
/* undo the quota changes */
key_payload_reserve(keyring,
keyring->datalen - KEYQUOTA_LINK_BYTES);
- goto error2;
+error_sem:
+ if (type == &key_type_keyring)
+ up_write(&keyring_serialise_link_sem);
+error_krsem:
+ up_write(&keyring->sem);
+ kleave(" = %d", ret);
+ return ret;
+}
-} /* end __key_link() */
+/*
+ * 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)
+{
+ if (key->type == &key_type_keyring)
+ /* check that we aren't going to create a cycle by linking one
+ * keyring to another */
+ return keyring_detect_cycle(keyring, key);
+ return 0;
+}
-/*****************************************************************************/
/*
- * link a key to a keyring
+ * 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.
*/
-int key_link(struct key *keyring, struct key *key)
+void __key_link(struct key *keyring, struct key *key,
+ unsigned long *_prealloc)
{
- int ret;
+ struct keyring_list *klist, *nklist;
- key_check(keyring);
- key_check(key);
+ nklist = (struct keyring_list *)(*_prealloc & ~KEY_LINK_FIXQUOTA);
+ *_prealloc = 0;
- down_write(&keyring->sem);
- ret = __key_link(keyring, key);
- up_write(&keyring->sem);
+ kenter("%d,%d,%p", keyring->serial, key->serial, nklist);
- return ret;
+ klist = rcu_dereference_protected(keyring->payload.subscriptions,
+ rwsem_is_locked(&keyring->sem));
-} /* end key_link() */
+ atomic_inc(&key->usage);
-EXPORT_SYMBOL(key_link);
+ /* there's a matching key we can displace or an empty slot in a newly
+ * allocated list we can fill */
+ if (nklist) {
+ kdebug("replace %hu/%hu/%hu",
+ nklist->delkey, nklist->nkeys, nklist->maxkeys);
+
+ nklist->keys[nklist->delkey] = key;
+
+ rcu_assign_pointer(keyring->payload.subscriptions, nklist);
+
+ /* dispose of the old keyring list and, if there was one, the
+ * displaced key */
+ if (klist) {
+ kdebug("dispose %hu/%hu/%hu",
+ klist->delkey, klist->nkeys, klist->maxkeys);
+ call_rcu(&klist->rcu, keyring_unlink_rcu_disposal);
+ }
+ } else {
+ /* there's sufficient slack space to append directly */
+ klist->keys[klist->nkeys] = key;
+ smp_wmb();
+ klist->nkeys++;
+ }
+}
-/*****************************************************************************/
/*
- * dispose of a keyring list after the RCU grace period, freeing the unlinked
- * key
+ * Finish linking a key into to a keyring.
+ *
+ * Must be called with __key_link_begin() having being called.
*/
-static void keyring_unlink_rcu_disposal(struct rcu_head *rcu)
+void __key_link_end(struct key *keyring, struct key_type *type,
+ unsigned long prealloc)
+ __releases(&keyring->sem)
{
- struct keyring_list *klist =
- container_of(rcu, struct keyring_list, rcu);
+ BUG_ON(type == NULL);
+ BUG_ON(type->name == NULL);
+ kenter("%d,%s,%lx", keyring->serial, type->name, prealloc);
- key_put(klist->keys[klist->delkey]);
- kfree(klist);
+ if (type == &key_type_keyring)
+ up_write(&keyring_serialise_link_sem);
-} /* end keyring_unlink_rcu_disposal() */
+ if (prealloc) {
+ 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);
+}
-/*****************************************************************************/
-/*
- * unlink the first link to a key from 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)
+{
+ unsigned long prealloc;
+ int ret;
+
+ key_check(keyring);
+ key_check(key);
+
+ ret = __key_link_begin(keyring, key->type, key->description, &prealloc);
+ if (ret == 0) {
+ ret = __key_link_check_live_key(keyring, key);
+ if (ret == 0)
+ __key_link(keyring, key, &prealloc);
+ __key_link_end(keyring, key->type, prealloc);
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL(key_link);
+
+/**
+ * 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)
{
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++)
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)
{
/* 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,
}
return ret;
+}
+EXPORT_SYMBOL(keyring_clear);
+
+/*
+ * Dispose of the links from a revoked keyring.
+ *
+ * This is called with the key sem write-locked.
+ */
+static void keyring_revoke(struct key *keyring)
+{
+ struct keyring_list *klist;
-} /* end keyring_clear() */
+ klist = rcu_dereference_locked_keyring(keyring);
-EXPORT_SYMBOL(keyring_clear);
+ /* adjust the quota */
+ key_payload_reserve(keyring, 0);
+
+ if (klist) {
+ rcu_assign_pointer(keyring->payload.subscriptions, NULL);
+ call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
+ }
+}
+
+/*
+ * Determine whether a key is dead.
+ */
+static bool key_is_dead(struct key *key, time_t limit)
+{
+ return test_bit(KEY_FLAG_DEAD, &key->flags) ||
+ (key->expiry > 0 && key->expiry <= limit);
+}
+
+/*
+ * 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)
+{
+ struct keyring_list *klist, *new;
+ struct key *key;
+ int loop, keep, max;
+
+ kenter("{%x,%s}", key_serial(keyring), keyring->description);
+
+ down_write(&keyring->sem);
+
+ klist = rcu_dereference_locked_keyring(keyring);
+ if (!klist)
+ goto no_klist;
+
+ /* work out how many subscriptions we're keeping */
+ keep = 0;
+ for (loop = klist->nkeys - 1; loop >= 0; loop--)
+ if (!key_is_dead(klist->keys[loop], limit))
+ keep++;
+
+ if (keep == klist->nkeys)
+ goto just_return;
+
+ /* allocate a new keyring payload */
+ max = roundup(keep, 4);
+ new = kmalloc(sizeof(struct keyring_list) + max * sizeof(struct key *),
+ GFP_KERNEL);
+ if (!new)
+ goto nomem;
+ new->maxkeys = max;
+ new->nkeys = 0;
+ new->delkey = 0;
+
+ /* install the live keys
+ * - must take care as expired keys may be updated back to life
+ */
+ keep = 0;
+ for (loop = klist->nkeys - 1; loop >= 0; loop--) {
+ key = klist->keys[loop];
+ if (!key_is_dead(key, limit)) {
+ if (keep >= max)
+ goto discard_new;
+ new->keys[keep++] = key_get(key);
+ }
+ }
+ new->nkeys = keep;
+
+ /* adjust the quota */
+ key_payload_reserve(keyring,
+ sizeof(struct keyring_list) +
+ KEYQUOTA_LINK_BYTES * keep);
+
+ if (keep == 0) {
+ rcu_assign_pointer(keyring->payload.subscriptions, NULL);
+ kfree(new);
+ } else {
+ rcu_assign_pointer(keyring->payload.subscriptions, new);
+ }
+
+ up_write(&keyring->sem);
+
+ call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
+ kleave(" [yes]");
+ return;
+
+discard_new:
+ new->nkeys = keep;
+ keyring_clear_rcu_disposal(&new->rcu);
+ up_write(&keyring->sem);
+ kleave(" [discard]");
+ return;
+
+just_return:
+ up_write(&keyring->sem);
+ kleave(" [no dead]");
+ return;
+
+no_klist:
+ up_write(&keyring->sem);
+ kleave(" [no_klist]");
+ return;
+
+nomem:
+ up_write(&keyring->sem);
+ kleave(" [oom]");
+}
Code Review / linux-3.10.git / blobdiff