-/* 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/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)))
+
/*
* when plumbing the depths of the key tree, this sets a hard limit set on how
* deep we're willing to go
unsigned bucket = 0;
for (; *desc; desc++)
- bucket += (unsigned char) *desc;
+ bucket += (unsigned char)*desc;
return bucket & (KEYRING_NAME_HASH_SIZE - 1);
}
* 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);
}
- 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]);
{
struct keyring_list *klist;
- if (keyring->description) {
+ if (keyring->description)
seq_puts(m, keyring->description);
- }
- else {
+ else
seq_puts(m, "[anon]");
- }
rcu_read_lock();
klist = rcu_dereference(keyring->payload.subscriptions);
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
*/
struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
- struct task_struct *ctx, unsigned long flags,
+ const struct cred *cred, unsigned long flags,
struct key *dest)
{
struct key *keyring;
int ret;
keyring = key_alloc(&key_type_keyring, description,
- uid, gid, ctx,
+ uid, gid, cred,
(KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL,
flags);
* - we propagate the possession attribute from the keyring ref to the key ref
*/
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_check(keyring);
/* top keyring must have search permission to begin the search */
- err = 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 must have search permissions */
if (key_task_permission(make_key_ref(key, possessed),
- context, KEY_SEARCH) < 0)
+ cred, KEY_SEARCH) < 0)
continue;
/* we set a different error code if we pass a negative key */
continue;
if (key_task_permission(make_key_ref(key, possessed),
- context, KEY_SEARCH) < 0)
+ cred, KEY_SEARCH) < 0)
continue;
/* stack the current position */
if (!type->match)
return ERR_PTR(-ENOKEY);
- return keyring_search_aux(keyring, current,
+ return keyring_search_aux(keyring, current->cred,
type, description, type->match);
} /* end keyring_search() */
rcu_read_unlock();
return ERR_PTR(-ENOKEY);
- found:
+found:
atomic_inc(&key->usage);
rcu_read_unlock();
return make_key_ref(key, possessed);
/*
* 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
+ * - normally only finds keyrings with search permission for the current process
*/
-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),
+ 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() */
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
- */
-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
struct keyring_list *klist =
container_of(rcu, struct keyring_list, rcu);
- key_put(klist->keys[klist->delkey]);
+ if (klist->delkey != USHORT_MAX)
+ 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 write-locked
- * - discard already extant link to matching key if there is one
+ * 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,
+ struct keyring_list **_prealloc)
+ __acquires(&keyring->sem)
{
struct keyring_list *klist, *nklist;
unsigned max;
size_t size;
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;
- /* see if there's a matching key we can displace */
- klist = keyring->payload.subscriptions;
+ /* 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);
- if (klist && klist->nkeys > 0) {
- struct key_type *type = key->type;
+ 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,
- key->description) == 0
+ description) == 0
) {
- /* found a match - replace with new key */
+ /* 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 error2;
-
- /* 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 error_sem;
+ /* note replacement slot */
+ klist->delkey = nklist->delkey = loop;
goto done;
}
}
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();
- }
- else {
+ /* there's sufficient slack space to append directly */
+ nklist = NULL;
+ } else {
/* grow the key list */
max = 4;
if (klist)
max += klist->maxkeys;
ret = -ENFILE;
- if (max > 65535)
- goto error3;
+ if (max > USHORT_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 = USHORT_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);
+ nklist->keys[nklist->delkey] = NULL;
}
done:
- ret = 0;
-error2:
- up_write(&keyring_serialise_link_sem);
-error:
- return ret;
+ *_prealloc = nklist;
+ 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 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
+ */
+void __key_link(struct key *keyring, struct key *key,
+ struct keyring_list **_prealloc)
+{
+ struct keyring_list *klist, *nklist;
+
+ nklist = *_prealloc;
+ *_prealloc = NULL;
+
+ kenter("%d,%d,%p", keyring->serial, key->serial, nklist);
+
+ klist = rcu_dereference_protected(keyring->payload.subscriptions,
+ rwsem_is_locked(&keyring->sem));
+
+ atomic_inc(&key->usage);
+
+ /* 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++;
+ }
+}
+
+/*
+ * 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)
+ __releases(&keyring->sem)
+{
+ BUG_ON(type == NULL);
+ BUG_ON(type->name == NULL);
+ kenter("%d,%s,%p", 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);
+ }
+ up_write(&keyring->sem);
+}
-/*****************************************************************************/
/*
* link a key to a keyring
*/
int key_link(struct key *keyring, struct key *key)
{
+ struct keyring_list *prealloc;
int ret;
key_check(keyring);
key_check(key);
- down_write(&keyring->sem);
- ret = __key_link(keyring, key);
- up_write(&keyring->sem);
+ 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;
-
-} /* end key_link() */
+}
EXPORT_SYMBOL(key_link);
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++)
/* 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,
*/
static void keyring_revoke(struct key *keyring)
{
- struct keyring_list *klist = keyring->payload.subscriptions;
+ struct keyring_list *klist;
+
+ klist = rcu_dereference_locked_keyring(keyring);
/* adjust the quota */
key_payload_reserve(keyring, 0);
}
} /* end keyring_revoke() */
+
+/*
+ * 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
+ */
+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]");
+}
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff