/* keyring.c: keyring handling
*
- * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
+ * Copyright (C) 2004-5 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>
*/
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_destroy(struct key *keyring);
static void keyring_describe(const struct key *keyring, struct seq_file *m);
.name = "keyring",
.def_datalen = sizeof(struct keyring_list),
.instantiate = keyring_instantiate,
- .duplicate = keyring_duplicate,
.match = keyring_match,
.destroy = keyring_destroy,
.describe = keyring_describe,
* 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);
/*****************************************************************************/
/*
} /* 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;
- sklist = source->payload.subscriptions;
-
- if (sklist && sklist->nkeys > 0) {
- max = sklist->nkeys;
- 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;
-
- 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);
-
- keyring->payload.subscriptions = klist;
- ret = 0;
- }
-
- error:
- return ret;
-
-} /* end keyring_duplicate() */
-
/*****************************************************************************/
/*
* match keyrings on their name
if (keyring->description) {
write_lock(&keyring_name_lock);
- list_del(&keyring->type_data.link);
+
+ if (keyring->type_data.link.next != NULL &&
+ !list_empty(&keyring->type_data.link))
+ list_del(&keyring->type_data.link);
+
write_unlock(&keyring_name_lock);
}
- klist = keyring->payload.subscriptions;
+ klist = rcu_dereference(keyring->payload.subscriptions);
if (klist) {
for (loop = klist->nkeys - 1; loop >= 0; loop--)
key_put(klist->keys[loop]);
seq_puts(m, "[anon]");
}
- klist = keyring->payload.subscriptions;
+ 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();
} /* end keyring_describe() */
/*****************************************************************************/
/*
* read a list of key IDs from the keyring's contents
+ * - the keyring's semaphore is read-locked
*/
static long keyring_read(const struct key *keyring,
char __user *buffer, size_t buflen)
int loop, ret;
ret = 0;
- klist = keyring->payload.subscriptions;
+ klist = rcu_dereference(keyring->payload.subscriptions);
if (klist) {
/* calculate how much data we could return */
int ret;
keyring = key_alloc(&key_type_keyring, description,
- uid, gid, KEY_USR_ALL, not_in_quota);
+ uid, gid,
+ (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL,
+ not_in_quota);
if (!IS_ERR(keyring)) {
- ret = key_instantiate_and_link(keyring, NULL, 0, dest);
+ ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
if (ret < 0) {
key_put(keyring);
keyring = ERR_PTR(ret);
* - 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 readlock the keyrings as we search down the tree
+ * - 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
*/
-struct key *keyring_search_aux(struct key *keyring,
- struct key_type *type,
- const void *description,
- key_match_func_t match)
+key_ref_t keyring_search_aux(key_ref_t keyring_ref,
+ struct task_struct *context,
+ struct key_type *type,
+ const void *description,
+ key_match_func_t match)
{
struct {
- struct key *keyring;
+ struct keyring_list *keylist;
int kix;
} stack[KEYRING_SEARCH_MAX_DEPTH];
struct keyring_list *keylist;
struct timespec now;
- struct key *key;
+ unsigned long possessed;
+ struct key *keyring, *key;
+ key_ref_t key_ref;
long err;
- int sp, psp, kix;
+ int sp, kix;
+ keyring = key_ref_to_ptr(keyring_ref);
+ possessed = is_key_possessed(keyring_ref);
key_check(keyring);
/* top keyring must have search permission to begin the search */
- key = ERR_PTR(-EACCES);
- if (!key_permission(keyring, KEY_SEARCH))
+ err = key_task_permission(keyring_ref, context, KEY_SEARCH);
+ if (err < 0) {
+ key_ref = ERR_PTR(err);
goto error;
+ }
- key = ERR_PTR(-ENOTDIR);
+ key_ref = ERR_PTR(-ENOTDIR);
if (keyring->type != &key_type_keyring)
goto error;
+ rcu_read_lock();
+
now = current_kernel_time();
err = -EAGAIN;
sp = 0;
/* start processing a new keyring */
- descend:
- read_lock(&keyring->lock);
- if (keyring->flags & KEY_FLAG_REVOKED)
+descend:
+ if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
goto not_this_keyring;
- keylist = keyring->payload.subscriptions;
+ keylist = rcu_dereference(keyring->payload.subscriptions);
if (!keylist)
goto not_this_keyring;
continue;
/* skip revoked keys and expired keys */
- if (key->flags & KEY_FLAG_REVOKED)
+ if (test_bit(KEY_FLAG_REVOKED, &key->flags))
continue;
if (key->expiry && now.tv_sec >= key->expiry)
continue;
/* key must have search permissions */
- if (!key_permission(key, KEY_SEARCH))
+ if (key_task_permission(make_key_ref(key, possessed),
+ context, KEY_SEARCH) < 0)
continue;
/* we set a different error code if we find a negative key */
- if (key->flags & KEY_FLAG_NEGATIVE) {
+ if (test_bit(KEY_FLAG_NEGATIVE, &key->flags)) {
err = -ENOKEY;
continue;
}
/* search through the keyrings nested in this one */
kix = 0;
- ascend:
- while (kix < keylist->nkeys) {
+ascend:
+ for (; kix < keylist->nkeys; kix++) {
key = keylist->keys[kix];
if (key->type != &key_type_keyring)
- goto next;
+ continue;
/* recursively search nested keyrings
* - only search keyrings for which we have search permission
*/
if (sp >= KEYRING_SEARCH_MAX_DEPTH)
- goto next;
-
- if (!key_permission(key, KEY_SEARCH))
- goto next;
+ continue;
- /* evade loops in the keyring tree */
- for (psp = 0; psp < sp; psp++)
- if (stack[psp].keyring == keyring)
- goto next;
+ if (key_task_permission(make_key_ref(key, possessed),
+ context, KEY_SEARCH) < 0)
+ continue;
/* stack the current position */
- stack[sp].keyring = keyring;
+ stack[sp].keylist = keylist;
stack[sp].kix = kix;
sp++;
/* begin again with the new keyring */
keyring = key;
goto descend;
-
- next:
- kix++;
}
/* the keyring we're looking at was disqualified or didn't contain a
* matching key */
- not_this_keyring:
- read_unlock(&keyring->lock);
-
+not_this_keyring:
if (sp > 0) {
/* resume the processing of a keyring higher up in the tree */
sp--;
- keyring = stack[sp].keyring;
- keylist = keyring->payload.subscriptions;
+ keylist = stack[sp].keylist;
kix = stack[sp].kix + 1;
goto ascend;
}
- key = ERR_PTR(err);
- goto error;
+ key_ref = ERR_PTR(err);
+ goto error_2;
/* we found a viable match */
- found:
+found:
atomic_inc(&key->usage);
- read_unlock(&keyring->lock);
-
- /* unwind the keyring stack */
- while (sp > 0) {
- sp--;
- read_unlock(&stack[sp].keyring->lock);
- }
-
key_check(key);
- error:
- return key;
+ key_ref = make_key_ref(key, possessed);
+error_2:
+ rcu_read_unlock();
+error:
+ return key_ref;
} /* end keyring_search_aux() */
* - we return -EAGAIN if we didn't find any matching key
* - we return -ENOKEY if we only found negative matching keys
*/
-struct key *keyring_search(struct key *keyring,
- struct key_type *type,
- const char *description)
+key_ref_t keyring_search(key_ref_t keyring,
+ struct key_type *type,
+ const char *description)
{
- return keyring_search_aux(keyring, type, description, type->match);
+ if (!type->match)
+ return ERR_PTR(-ENOKEY);
+
+ return keyring_search_aux(keyring, current,
+ type, description, type->match);
} /* end keyring_search() */
/*
* search the given keyring only (no recursion)
* - keyring must be locked by caller
+ * - caller must guarantee that the keyring is a keyring
*/
-struct key *__keyring_search_one(struct key *keyring,
- const struct key_type *ktype,
- const char *description,
- key_perm_t perm)
+key_ref_t __keyring_search_one(key_ref_t keyring_ref,
+ const struct key_type *ktype,
+ const char *description,
+ key_perm_t perm)
{
struct keyring_list *klist;
- struct key *key;
+ unsigned long possessed;
+ struct key *keyring, *key;
int loop;
- klist = keyring->payload.subscriptions;
+ keyring = key_ref_to_ptr(keyring_ref);
+ possessed = is_key_possessed(keyring_ref);
+
+ rcu_read_lock();
+
+ klist = rcu_dereference(keyring->payload.subscriptions);
if (klist) {
for (loop = 0; loop < klist->nkeys; loop++) {
key = klist->keys[loop];
if (key->type == ktype &&
- key->type->match(key, description) &&
- key_permission(key, perm) &&
- !(key->flags & KEY_FLAG_REVOKED)
+ (!key->type->match ||
+ key->type->match(key, description)) &&
+ key_permission(make_key_ref(key, possessed),
+ perm) == 0 &&
+ !test_bit(KEY_FLAG_REVOKED, &key->flags)
)
goto found;
}
}
- key = ERR_PTR(-ENOKEY);
- goto error;
+ rcu_read_unlock();
+ return ERR_PTR(-ENOKEY);
found:
atomic_inc(&key->usage);
- error:
- return key;
+ rcu_read_unlock();
+ return make_key_ref(key, possessed);
} /* end __keyring_search_one() */
&keyring_name_hash[bucket],
type_data.link
) {
- if (keyring->flags & KEY_FLAG_REVOKED)
+ if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
continue;
if (strcmp(keyring->description, name) != 0)
continue;
- if (!key_permission(keyring, KEY_SEARCH))
+ if (key_permission(make_key_ref(keyring, 0),
+ KEY_SEARCH) < 0)
continue;
/* found a potential candidate, but we still need to
static int keyring_detect_cycle(struct key *A, struct key *B)
{
struct {
- struct key *subtree;
+ struct keyring_list *keylist;
int kix;
} stack[KEYRING_SEARCH_MAX_DEPTH];
struct key *subtree, *key;
int sp, kix, ret;
+ rcu_read_lock();
+
ret = -EDEADLK;
if (A == B)
- goto error;
+ goto cycle_detected;
subtree = B;
sp = 0;
/* start processing a new keyring */
descend:
- read_lock(&subtree->lock);
- if (subtree->flags & KEY_FLAG_REVOKED)
+ if (test_bit(KEY_FLAG_REVOKED, &subtree->flags))
goto not_this_keyring;
- keylist = subtree->payload.subscriptions;
+ keylist = rcu_dereference(subtree->payload.subscriptions);
if (!keylist)
goto not_this_keyring;
kix = 0;
goto too_deep;
/* stack the current position */
- stack[sp].subtree = subtree;
+ stack[sp].keylist = keylist;
stack[sp].kix = kix;
sp++;
/* the keyring we're looking at was disqualified or didn't contain a
* matching key */
not_this_keyring:
- read_unlock(&subtree->lock);
-
if (sp > 0) {
/* resume the checking of a keyring higher up in the tree */
sp--;
- subtree = stack[sp].subtree;
- keylist = subtree->payload.subscriptions;
+ keylist = stack[sp].keylist;
kix = stack[sp].kix + 1;
goto ascend;
}
ret = 0; /* no cycles detected */
error:
+ rcu_read_unlock();
return ret;
too_deep:
ret = -ELOOP;
- goto error_unwind;
+ goto error;
+
cycle_detected:
ret = -EDEADLK;
- error_unwind:
- read_unlock(&subtree->lock);
-
- /* unwind the keyring stack */
- while (sp > 0) {
- sp--;
- read_unlock(&stack[sp].subtree->lock);
- }
-
goto error;
} /* end keyring_detect_cycle() */
+/*****************************************************************************/
+/*
+ * dispose of a keyring list after the RCU grace period
+ */
+static void keyring_link_rcu_disposal(struct rcu_head *rcu)
+{
+ struct keyring_list *klist =
+ container_of(rcu, struct keyring_list, rcu);
+
+ kfree(klist);
+
+} /* end keyring_link_rcu_disposal() */
+
+/*****************************************************************************/
+/*
+ * 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);
+
+ key_put(klist->keys[klist->delkey]);
+ kfree(klist);
+
+} /* end keyring_unlink_rcu_disposal() */
+
/*****************************************************************************/
/*
* link a key into to a keyring
- * - must be called with the keyring's semaphore held
+ * - must be called with the keyring's semaphore write-locked
+ * - discard already extant link to matching key if there is one
*/
int __key_link(struct key *keyring, struct key *key)
{
struct keyring_list *klist, *nklist;
unsigned max;
size_t size;
- int ret;
+ int loop, ret;
ret = -EKEYREVOKED;
- if (keyring->flags & KEY_FLAG_REVOKED)
+ if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
goto error;
ret = -ENOTDIR;
goto error2;
}
+ /* see if there's a matching key we can displace */
+ klist = keyring->payload.subscriptions;
+
+ if (klist && klist->nkeys > 0) {
+ struct key_type *type = key->type;
+
+ for (loop = klist->nkeys - 1; loop >= 0; loop--) {
+ if (klist->keys[loop]->type == type &&
+ strcmp(klist->keys[loop]->description,
+ key->description) == 0
+ ) {
+ /* found a match - replace with new key */
+ size = sizeof(struct key *) * klist->maxkeys;
+ size += sizeof(*klist);
+ BUG_ON(size > PAGE_SIZE);
+
+ ret = -ENOMEM;
+ nklist = kmalloc(size, GFP_KERNEL);
+ if (!nklist)
+ goto error2;
+
+ memcpy(nklist, klist, size);
+
+ /* replace matched key */
+ atomic_inc(&key->usage);
+ nklist->keys[loop] = key;
+
+ rcu_assign_pointer(
+ keyring->payload.subscriptions,
+ nklist);
+
+ /* dispose of the old keyring list and the
+ * displaced key */
+ klist->delkey = loop;
+ call_rcu(&klist->rcu,
+ keyring_unlink_rcu_disposal);
+
+ goto done;
+ }
+ }
+ }
+
/* check that we aren't going to overrun the user's quota */
ret = key_payload_reserve(keyring,
keyring->datalen + KEYQUOTA_LINK_BYTES);
/* there's sufficient slack space to add directly */
atomic_inc(&key->usage);
- write_lock(&keyring->lock);
- klist->keys[klist->nkeys++] = key;
- write_unlock(&keyring->lock);
-
- ret = 0;
+ klist->keys[klist->nkeys] = key;
+ smp_wmb();
+ klist->nkeys++;
+ smp_wmb();
}
else {
/* grow the key list */
max += klist->maxkeys;
ret = -ENFILE;
- size = sizeof(*klist) + sizeof(*key) * max;
+ if (max > 65535)
+ goto error3;
+ size = sizeof(*klist) + sizeof(struct key *) * max;
if (size > PAGE_SIZE)
goto error3;
/* add the key into the new space */
atomic_inc(&key->usage);
-
- write_lock(&keyring->lock);
- keyring->payload.subscriptions = nklist;
nklist->keys[nklist->nkeys++] = key;
- write_unlock(&keyring->lock);
- /* dispose of the old keyring list */
- kfree(klist);
+ rcu_assign_pointer(keyring->payload.subscriptions, nklist);
- ret = 0;
+ /* dispose of the old keyring list */
+ if (klist)
+ call_rcu(&klist->rcu, keyring_link_rcu_disposal);
}
- error2:
+done:
+ ret = 0;
+error2:
up_write(&keyring_serialise_link_sem);
- error:
+error:
return ret;
- error3:
+error3:
/* undo the quota changes */
key_payload_reserve(keyring,
keyring->datalen - KEYQUOTA_LINK_BYTES);
*/
int key_unlink(struct key *keyring, struct key *key)
{
- struct keyring_list *klist;
+ struct keyring_list *klist, *nklist;
int loop, ret;
key_check(keyring);
ret = -ENOENT;
goto error;
- key_is_present:
+key_is_present:
+ /* we need to copy the key list for RCU purposes */
+ nklist = kmalloc(sizeof(*klist) +
+ sizeof(struct key *) * klist->maxkeys,
+ GFP_KERNEL);
+ if (!nklist)
+ goto nomem;
+ nklist->maxkeys = klist->maxkeys;
+ nklist->nkeys = klist->nkeys - 1;
+
+ if (loop > 0)
+ memcpy(&nklist->keys[0],
+ &klist->keys[0],
+ loop * sizeof(struct key *));
+
+ if (loop < nklist->nkeys)
+ memcpy(&nklist->keys[loop],
+ &klist->keys[loop + 1],
+ (nklist->nkeys - loop) * sizeof(struct key *));
+
/* adjust the user's quota */
key_payload_reserve(keyring,
keyring->datalen - KEYQUOTA_LINK_BYTES);
- /* shuffle down the key pointers
- * - it might be worth shrinking the allocated memory, but that runs
- * the risk of ENOMEM as we would have to copy
- */
- write_lock(&keyring->lock);
+ rcu_assign_pointer(keyring->payload.subscriptions, nklist);
- klist->nkeys--;
- if (loop < klist->nkeys)
- memcpy(&klist->keys[loop],
- &klist->keys[loop + 1],
- (klist->nkeys - loop) * sizeof(struct key *));
+ up_write(&keyring->sem);
- write_unlock(&keyring->lock);
+ /* schedule for later cleanup */
+ klist->delkey = loop;
+ call_rcu(&klist->rcu, keyring_unlink_rcu_disposal);
- up_write(&keyring->sem);
- key_put(key);
ret = 0;
- error:
+error:
return ret;
+nomem:
+ 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
+ */
+static void keyring_clear_rcu_disposal(struct rcu_head *rcu)
+{
+ struct keyring_list *klist;
+ int loop;
+
+ klist = container_of(rcu, struct keyring_list, rcu);
+
+ for (loop = klist->nkeys - 1; loop >= 0; loop--)
+ key_put(klist->keys[loop]);
+
+ kfree(klist);
+
+} /* end keyring_clear_rcu_disposal() */
+
/*****************************************************************************/
/*
* clear the specified process keyring
int keyring_clear(struct key *keyring)
{
struct keyring_list *klist;
- int loop, ret;
+ int ret;
ret = -ENOTDIR;
if (keyring->type == &key_type_keyring) {
key_payload_reserve(keyring,
sizeof(struct keyring_list));
- write_lock(&keyring->lock);
- keyring->payload.subscriptions = NULL;
- write_unlock(&keyring->lock);
+ rcu_assign_pointer(keyring->payload.subscriptions,
+ NULL);
}
up_write(&keyring->sem);
/* free the keys after the locks have been dropped */
- if (klist) {
- for (loop = klist->nkeys - 1; loop >= 0; loop--)
- key_put(klist->keys[loop]);
-
- kfree(klist);
- }
+ if (klist)
+ call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
ret = 0;
}
git://git.onelab.eu / linux-2.6.git / blobdiff