linux/security/keys/key.c
Dan Carpenter 38327424b4 KEYS: potential uninitialized variable
If __key_link_begin() failed then "edit" would be uninitialized.  I've
added a check to fix that.

This allows a random user to crash the kernel, though it's quite
difficult to achieve.  There are three ways it can be done as the user
would have to cause an error to occur in __key_link():

 (1) Cause the kernel to run out of memory.  In practice, this is difficult
     to achieve without ENOMEM cropping up elsewhere and aborting the
     attempt.

 (2) Revoke the destination keyring between the keyring ID being looked up
     and it being tested for revocation.  In practice, this is difficult to
     time correctly because the KEYCTL_REJECT function can only be used
     from the request-key upcall process.  Further, users can only make use
     of what's in /sbin/request-key.conf, though this does including a
     rejection debugging test - which means that the destination keyring
     has to be the caller's session keyring in practice.

 (3) Have just enough key quota available to create a key, a new session
     keyring for the upcall and a link in the session keyring, but not then
     sufficient quota to create a link in the nominated destination keyring
     so that it fails with EDQUOT.

The bug can be triggered using option (3) above using something like the
following:

	echo 80 >/proc/sys/kernel/keys/root_maxbytes
	keyctl request2 user debug:fred negate @t

The above sets the quota to something much lower (80) to make the bug
easier to trigger, but this is dependent on the system.  Note also that
the name of the keyring created contains a random number that may be
between 1 and 10 characters in size, so may throw the test off by
changing the amount of quota used.

Assuming the failure occurs, something like the following will be seen:

	kfree_debugcheck: out of range ptr 6b6b6b6b6b6b6b68h
	------------[ cut here ]------------
	kernel BUG at ../mm/slab.c:2821!
	...
	RIP: 0010:[<ffffffff811600f9>] kfree_debugcheck+0x20/0x25
	RSP: 0018:ffff8804014a7de8  EFLAGS: 00010092
	RAX: 0000000000000034 RBX: 6b6b6b6b6b6b6b68 RCX: 0000000000000000
	RDX: 0000000000040001 RSI: 00000000000000f6 RDI: 0000000000000300
	RBP: ffff8804014a7df0 R08: 0000000000000001 R09: 0000000000000000
	R10: ffff8804014a7e68 R11: 0000000000000054 R12: 0000000000000202
	R13: ffffffff81318a66 R14: 0000000000000000 R15: 0000000000000001
	...
	Call Trace:
	  kfree+0xde/0x1bc
	  assoc_array_cancel_edit+0x1f/0x36
	  __key_link_end+0x55/0x63
	  key_reject_and_link+0x124/0x155
	  keyctl_reject_key+0xb6/0xe0
	  keyctl_negate_key+0x10/0x12
	  SyS_keyctl+0x9f/0xe7
	  do_syscall_64+0x63/0x13a
	  entry_SYSCALL64_slow_path+0x25/0x25

Fixes: f70e2e0619 ('KEYS: Do preallocation for __key_link()')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-16 17:15:04 -10:00

1169 lines
30 KiB
C

/* Basic authentication token and access key management
*
* Copyright (C) 2004-2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/poison.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/security.h>
#include <linux/workqueue.h>
#include <linux/random.h>
#include <linux/err.h>
#include "internal.h"
struct kmem_cache *key_jar;
struct rb_root key_serial_tree; /* tree of keys indexed by serial */
DEFINE_SPINLOCK(key_serial_lock);
struct rb_root key_user_tree; /* tree of quota records indexed by UID */
DEFINE_SPINLOCK(key_user_lock);
unsigned int key_quota_root_maxkeys = 1000000; /* root's key count quota */
unsigned int key_quota_root_maxbytes = 25000000; /* root's key space quota */
unsigned int key_quota_maxkeys = 200; /* general key count quota */
unsigned int key_quota_maxbytes = 20000; /* general key space quota */
static LIST_HEAD(key_types_list);
static DECLARE_RWSEM(key_types_sem);
/* We serialise key instantiation and link */
DEFINE_MUTEX(key_construction_mutex);
#ifdef KEY_DEBUGGING
void __key_check(const struct key *key)
{
printk("__key_check: key %p {%08x} should be {%08x}\n",
key, key->magic, KEY_DEBUG_MAGIC);
BUG();
}
#endif
/*
* Get the key quota record for a user, allocating a new record if one doesn't
* already exist.
*/
struct key_user *key_user_lookup(kuid_t uid)
{
struct key_user *candidate = NULL, *user;
struct rb_node *parent = NULL;
struct rb_node **p;
try_again:
p = &key_user_tree.rb_node;
spin_lock(&key_user_lock);
/* search the tree for a user record with a matching UID */
while (*p) {
parent = *p;
user = rb_entry(parent, struct key_user, node);
if (uid_lt(uid, user->uid))
p = &(*p)->rb_left;
else if (uid_gt(uid, user->uid))
p = &(*p)->rb_right;
else
goto found;
}
/* if we get here, we failed to find a match in the tree */
if (!candidate) {
/* allocate a candidate user record if we don't already have
* one */
spin_unlock(&key_user_lock);
user = NULL;
candidate = kmalloc(sizeof(struct key_user), GFP_KERNEL);
if (unlikely(!candidate))
goto out;
/* the allocation may have scheduled, so we need to repeat the
* search lest someone else added the record whilst we were
* asleep */
goto try_again;
}
/* if we get here, then the user record still hadn't appeared on the
* second pass - so we use the candidate record */
atomic_set(&candidate->usage, 1);
atomic_set(&candidate->nkeys, 0);
atomic_set(&candidate->nikeys, 0);
candidate->uid = uid;
candidate->qnkeys = 0;
candidate->qnbytes = 0;
spin_lock_init(&candidate->lock);
mutex_init(&candidate->cons_lock);
rb_link_node(&candidate->node, parent, p);
rb_insert_color(&candidate->node, &key_user_tree);
spin_unlock(&key_user_lock);
user = candidate;
goto out;
/* okay - we found a user record for this UID */
found:
atomic_inc(&user->usage);
spin_unlock(&key_user_lock);
kfree(candidate);
out:
return user;
}
/*
* Dispose of a user structure
*/
void key_user_put(struct key_user *user)
{
if (atomic_dec_and_lock(&user->usage, &key_user_lock)) {
rb_erase(&user->node, &key_user_tree);
spin_unlock(&key_user_lock);
kfree(user);
}
}
/*
* 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)
{
struct rb_node *parent, **p;
struct key *xkey;
/* propose a random serial number and look for a hole for it in the
* serial number tree */
do {
get_random_bytes(&key->serial, sizeof(key->serial));
key->serial >>= 1; /* negative numbers are not permitted */
} while (key->serial < 3);
spin_lock(&key_serial_lock);
attempt_insertion:
parent = NULL;
p = &key_serial_tree.rb_node;
while (*p) {
parent = *p;
xkey = rb_entry(parent, struct key, serial_node);
if (key->serial < xkey->serial)
p = &(*p)->rb_left;
else if (key->serial > xkey->serial)
p = &(*p)->rb_right;
else
goto serial_exists;
}
/* we've found a suitable hole - arrange for this key to occupy it */
rb_link_node(&key->serial_node, parent, p);
rb_insert_color(&key->serial_node, &key_serial_tree);
spin_unlock(&key_serial_lock);
return;
/* we found a key with the proposed serial number - walk the tree from
* that point looking for the next unused serial number */
serial_exists:
for (;;) {
key->serial++;
if (key->serial < 3) {
key->serial = 3;
goto attempt_insertion;
}
parent = rb_next(parent);
if (!parent)
goto attempt_insertion;
xkey = rb_entry(parent, struct key, serial_node);
if (key->serial < xkey->serial)
goto attempt_insertion;
}
}
/**
* 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.
* @restrict_link: Optional link restriction method for new keyrings.
*
* 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,
kuid_t uid, kgid_t gid, const struct cred *cred,
key_perm_t perm, unsigned long flags,
int (*restrict_link)(struct key *,
const struct key_type *,
const union key_payload *))
{
struct key_user *user = NULL;
struct key *key;
size_t desclen, quotalen;
int ret;
key = ERR_PTR(-EINVAL);
if (!desc || !*desc)
goto error;
if (type->vet_description) {
ret = type->vet_description(desc);
if (ret < 0) {
key = ERR_PTR(ret);
goto error;
}
}
desclen = strlen(desc);
quotalen = desclen + 1 + type->def_datalen;
/* get hold of the key tracking for this user */
user = key_user_lookup(uid);
if (!user)
goto no_memory_1;
/* check that the user's quota permits allocation of another key and
* its description */
if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
unsigned maxkeys = uid_eq(uid, GLOBAL_ROOT_UID) ?
key_quota_root_maxkeys : key_quota_maxkeys;
unsigned maxbytes = uid_eq(uid, GLOBAL_ROOT_UID) ?
key_quota_root_maxbytes : key_quota_maxbytes;
spin_lock(&user->lock);
if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
if (user->qnkeys + 1 >= maxkeys ||
user->qnbytes + quotalen >= maxbytes ||
user->qnbytes + quotalen < user->qnbytes)
goto no_quota;
}
user->qnkeys++;
user->qnbytes += quotalen;
spin_unlock(&user->lock);
}
/* allocate and initialise the key and its description */
key = kmem_cache_zalloc(key_jar, GFP_KERNEL);
if (!key)
goto no_memory_2;
key->index_key.desc_len = desclen;
key->index_key.description = kmemdup(desc, desclen + 1, GFP_KERNEL);
if (!key->index_key.description)
goto no_memory_3;
atomic_set(&key->usage, 1);
init_rwsem(&key->sem);
lockdep_set_class(&key->sem, &type->lock_class);
key->index_key.type = type;
key->user = user;
key->quotalen = quotalen;
key->datalen = type->def_datalen;
key->uid = uid;
key->gid = gid;
key->perm = perm;
key->restrict_link = restrict_link;
if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
key->flags |= 1 << KEY_FLAG_IN_QUOTA;
if (flags & KEY_ALLOC_BUILT_IN)
key->flags |= 1 << KEY_FLAG_BUILTIN;
#ifdef KEY_DEBUGGING
key->magic = KEY_DEBUG_MAGIC;
#endif
/* let the security module know about the key */
ret = security_key_alloc(key, cred, flags);
if (ret < 0)
goto security_error;
/* publish the key by giving it a serial number */
atomic_inc(&user->nkeys);
key_alloc_serial(key);
error:
return key;
security_error:
kfree(key->description);
kmem_cache_free(key_jar, key);
if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
spin_lock(&user->lock);
user->qnkeys--;
user->qnbytes -= quotalen;
spin_unlock(&user->lock);
}
key_user_put(user);
key = ERR_PTR(ret);
goto error;
no_memory_3:
kmem_cache_free(key_jar, key);
no_memory_2:
if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
spin_lock(&user->lock);
user->qnkeys--;
user->qnbytes -= quotalen;
spin_unlock(&user->lock);
}
key_user_put(user);
no_memory_1:
key = ERR_PTR(-ENOMEM);
goto error;
no_quota:
spin_unlock(&user->lock);
key_user_put(user);
key = ERR_PTR(-EDQUOT);
goto error;
}
EXPORT_SYMBOL(key_alloc);
/**
* 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)
{
int delta = (int)datalen - key->datalen;
int ret = 0;
key_check(key);
/* contemplate the quota adjustment */
if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
unsigned maxbytes = uid_eq(key->user->uid, GLOBAL_ROOT_UID) ?
key_quota_root_maxbytes : key_quota_maxbytes;
spin_lock(&key->user->lock);
if (delta > 0 &&
(key->user->qnbytes + delta >= maxbytes ||
key->user->qnbytes + delta < key->user->qnbytes)) {
ret = -EDQUOT;
}
else {
key->user->qnbytes += delta;
key->quotalen += delta;
}
spin_unlock(&key->user->lock);
}
/* change the recorded data length if that didn't generate an error */
if (ret == 0)
key->datalen = datalen;
return ret;
}
EXPORT_SYMBOL(key_payload_reserve);
/*
* 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,
struct key_preparsed_payload *prep,
struct key *keyring,
struct key *authkey,
struct assoc_array_edit **_edit)
{
int ret, awaken;
key_check(key);
key_check(keyring);
awaken = 0;
ret = -EBUSY;
mutex_lock(&key_construction_mutex);
/* can't instantiate twice */
if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
/* instantiate the key */
ret = key->type->instantiate(key, prep);
if (ret == 0) {
/* mark the key as being instantiated */
atomic_inc(&key->user->nikeys);
set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
awaken = 1;
/* and link it into the destination keyring */
if (keyring) {
if (test_bit(KEY_FLAG_KEEP, &keyring->flags))
set_bit(KEY_FLAG_KEEP, &key->flags);
__key_link(key, _edit);
}
/* disable the authorisation key */
if (authkey)
key_revoke(authkey);
if (prep->expiry != TIME_T_MAX) {
key->expiry = prep->expiry;
key_schedule_gc(prep->expiry + key_gc_delay);
}
}
}
mutex_unlock(&key_construction_mutex);
/* wake up anyone waiting for a key to be constructed */
if (awaken)
wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
return ret;
}
/**
* 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,
size_t datalen,
struct key *keyring,
struct key *authkey)
{
struct key_preparsed_payload prep;
struct assoc_array_edit *edit;
int ret;
memset(&prep, 0, sizeof(prep));
prep.data = data;
prep.datalen = datalen;
prep.quotalen = key->type->def_datalen;
prep.expiry = TIME_T_MAX;
if (key->type->preparse) {
ret = key->type->preparse(&prep);
if (ret < 0)
goto error;
}
if (keyring) {
if (keyring->restrict_link) {
ret = keyring->restrict_link(keyring, key->type,
&prep.payload);
if (ret < 0)
goto error;
}
ret = __key_link_begin(keyring, &key->index_key, &edit);
if (ret < 0)
goto error;
}
ret = __key_instantiate_and_link(key, &prep, keyring, authkey, &edit);
if (keyring)
__key_link_end(keyring, &key->index_key, edit);
error:
if (key->type->preparse)
key->type->free_preparse(&prep);
return ret;
}
EXPORT_SYMBOL(key_instantiate_and_link);
/**
* key_reject_and_link - Negatively instantiate a key and link it into the keyring.
* @key: The key to instantiate.
* @timeout: The timeout on the negative key.
* @error: The error to return when the key is hit.
* @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 stored error 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 the stored error code (typically 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_reject_and_link(struct key *key,
unsigned timeout,
unsigned error,
struct key *keyring,
struct key *authkey)
{
struct assoc_array_edit *edit;
struct timespec now;
int ret, awaken, link_ret = 0;
key_check(key);
key_check(keyring);
awaken = 0;
ret = -EBUSY;
if (keyring) {
if (keyring->restrict_link)
return -EPERM;
link_ret = __key_link_begin(keyring, &key->index_key, &edit);
}
mutex_lock(&key_construction_mutex);
/* can't instantiate twice */
if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
/* mark the key as being negatively instantiated */
atomic_inc(&key->user->nikeys);
key->reject_error = -error;
smp_wmb();
set_bit(KEY_FLAG_NEGATIVE, &key->flags);
set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
now = current_kernel_time();
key->expiry = now.tv_sec + timeout;
key_schedule_gc(key->expiry + key_gc_delay);
if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
awaken = 1;
ret = 0;
/* and link it into the destination keyring */
if (keyring && link_ret == 0)
__key_link(key, &edit);
/* disable the authorisation key */
if (authkey)
key_revoke(authkey);
}
mutex_unlock(&key_construction_mutex);
if (keyring && link_ret == 0)
__key_link_end(keyring, &key->index_key, edit);
/* wake up anyone waiting for a key to be constructed */
if (awaken)
wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
return ret == 0 ? link_ret : ret;
}
EXPORT_SYMBOL(key_reject_and_link);
/**
* 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)
{
if (key) {
key_check(key);
if (atomic_dec_and_test(&key->usage))
schedule_work(&key_gc_work);
}
}
EXPORT_SYMBOL(key_put);
/*
* Find a key by its serial number.
*/
struct key *key_lookup(key_serial_t id)
{
struct rb_node *n;
struct key *key;
spin_lock(&key_serial_lock);
/* search the tree for the specified key */
n = key_serial_tree.rb_node;
while (n) {
key = rb_entry(n, struct key, serial_node);
if (id < key->serial)
n = n->rb_left;
else if (id > key->serial)
n = n->rb_right;
else
goto found;
}
not_found:
key = ERR_PTR(-ENOKEY);
goto error;
found:
/* pretend it doesn't exist if it is awaiting deletion */
if (atomic_read(&key->usage) == 0)
goto not_found;
/* this races with key_put(), but that doesn't matter since key_put()
* doesn't actually change the key
*/
__key_get(key);
error:
spin_unlock(&key_serial_lock);
return key;
}
/*
* 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)
{
struct key_type *ktype;
down_read(&key_types_sem);
/* look up the key type to see if it's one of the registered kernel
* types */
list_for_each_entry(ktype, &key_types_list, link) {
if (strcmp(ktype->name, type) == 0)
goto found_kernel_type;
}
up_read(&key_types_sem);
ktype = ERR_PTR(-ENOKEY);
found_kernel_type:
return ktype;
}
void key_set_timeout(struct key *key, unsigned timeout)
{
struct timespec now;
time_t expiry = 0;
/* make the changes with the locks held to prevent races */
down_write(&key->sem);
if (timeout > 0) {
now = current_kernel_time();
expiry = now.tv_sec + timeout;
}
key->expiry = expiry;
key_schedule_gc(key->expiry + key_gc_delay);
up_write(&key->sem);
}
EXPORT_SYMBOL_GPL(key_set_timeout);
/*
* Unlock a key type locked by key_type_lookup().
*/
void key_type_put(struct key_type *ktype)
{
up_read(&key_types_sem);
}
/*
* 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,
struct key_preparsed_payload *prep)
{
struct key *key = key_ref_to_ptr(key_ref);
int ret;
/* need write permission on the key to update it */
ret = key_permission(key_ref, KEY_NEED_WRITE);
if (ret < 0)
goto error;
ret = -EEXIST;
if (!key->type->update)
goto error;
down_write(&key->sem);
ret = key->type->update(key, prep);
if (ret == 0)
/* updating a negative key instantiates it */
clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
up_write(&key->sem);
if (ret < 0)
goto error;
out:
return key_ref;
error:
key_put(key);
key_ref = ERR_PTR(ret);
goto out;
}
/**
* 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,
const char *description,
const void *payload,
size_t plen,
key_perm_t perm,
unsigned long flags)
{
struct keyring_index_key index_key = {
.description = description,
};
struct key_preparsed_payload prep;
struct assoc_array_edit *edit;
const struct cred *cred = current_cred();
struct key *keyring, *key = NULL;
key_ref_t key_ref;
int ret;
int (*restrict_link)(struct key *,
const struct key_type *,
const union key_payload *) = NULL;
/* look up the key type to see if it's one of the registered kernel
* types */
index_key.type = key_type_lookup(type);
if (IS_ERR(index_key.type)) {
key_ref = ERR_PTR(-ENODEV);
goto error;
}
key_ref = ERR_PTR(-EINVAL);
if (!index_key.type->instantiate ||
(!index_key.description && !index_key.type->preparse))
goto error_put_type;
keyring = key_ref_to_ptr(keyring_ref);
key_check(keyring);
key_ref = ERR_PTR(-EPERM);
if (!(flags & KEY_ALLOC_BYPASS_RESTRICTION))
restrict_link = keyring->restrict_link;
key_ref = ERR_PTR(-ENOTDIR);
if (keyring->type != &key_type_keyring)
goto error_put_type;
memset(&prep, 0, sizeof(prep));
prep.data = payload;
prep.datalen = plen;
prep.quotalen = index_key.type->def_datalen;
prep.expiry = TIME_T_MAX;
if (index_key.type->preparse) {
ret = index_key.type->preparse(&prep);
if (ret < 0) {
key_ref = ERR_PTR(ret);
goto error_free_prep;
}
if (!index_key.description)
index_key.description = prep.description;
key_ref = ERR_PTR(-EINVAL);
if (!index_key.description)
goto error_free_prep;
}
index_key.desc_len = strlen(index_key.description);
if (restrict_link) {
ret = restrict_link(keyring, index_key.type, &prep.payload);
if (ret < 0) {
key_ref = ERR_PTR(ret);
goto error_free_prep;
}
}
ret = __key_link_begin(keyring, &index_key, &edit);
if (ret < 0) {
key_ref = ERR_PTR(ret);
goto error_free_prep;
}
/* if we're going to allocate a new key, we're going to have
* to modify the keyring */
ret = key_permission(keyring_ref, KEY_NEED_WRITE);
if (ret < 0) {
key_ref = ERR_PTR(ret);
goto error_link_end;
}
/* if it's possible to update this type of key, search for an existing
* key of the same type and description in the destination keyring and
* update that instead if possible
*/
if (index_key.type->update) {
key_ref = find_key_to_update(keyring_ref, &index_key);
if (key_ref)
goto found_matching_key;
}
/* if the client doesn't provide, decide on the permissions we want */
if (perm == KEY_PERM_UNDEF) {
perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
perm |= KEY_USR_VIEW;
if (index_key.type->read)
perm |= KEY_POS_READ;
if (index_key.type == &key_type_keyring ||
index_key.type->update)
perm |= KEY_POS_WRITE;
}
/* allocate a new key */
key = key_alloc(index_key.type, index_key.description,
cred->fsuid, cred->fsgid, cred, perm, flags, NULL);
if (IS_ERR(key)) {
key_ref = ERR_CAST(key);
goto error_link_end;
}
/* instantiate it and link it into the target keyring */
ret = __key_instantiate_and_link(key, &prep, keyring, NULL, &edit);
if (ret < 0) {
key_put(key);
key_ref = ERR_PTR(ret);
goto error_link_end;
}
key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
error_link_end:
__key_link_end(keyring, &index_key, edit);
error_free_prep:
if (index_key.type->preparse)
index_key.type->free_preparse(&prep);
error_put_type:
key_type_put(index_key.type);
error:
return key_ref;
found_matching_key:
/* we found a matching key, so we're going to try to update it
* - we can drop the locks first as we have the key pinned
*/
__key_link_end(keyring, &index_key, edit);
key_ref = __key_update(key_ref, &prep);
goto error_free_prep;
}
EXPORT_SYMBOL(key_create_or_update);
/**
* 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)
{
struct key_preparsed_payload prep;
struct key *key = key_ref_to_ptr(key_ref);
int ret;
key_check(key);
/* the key must be writable */
ret = key_permission(key_ref, KEY_NEED_WRITE);
if (ret < 0)
goto error;
/* attempt to update it if supported */
ret = -EOPNOTSUPP;
if (!key->type->update)
goto error;
memset(&prep, 0, sizeof(prep));
prep.data = payload;
prep.datalen = plen;
prep.quotalen = key->type->def_datalen;
prep.expiry = TIME_T_MAX;
if (key->type->preparse) {
ret = key->type->preparse(&prep);
if (ret < 0)
goto error;
}
down_write(&key->sem);
ret = key->type->update(key, &prep);
if (ret == 0)
/* updating a negative key instantiates it */
clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
up_write(&key->sem);
error:
if (key->type->preparse)
key->type->free_preparse(&prep);
return ret;
}
EXPORT_SYMBOL(key_update);
/**
* 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)
{
struct timespec now;
time_t time;
key_check(key);
/* make sure no one's trying to change or use the key when we mark it
* - we tell lockdep that we might nest because we might be revoking an
* authorisation key whilst holding the sem on a key we've just
* instantiated
*/
down_write_nested(&key->sem, 1);
if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags) &&
key->type->revoke)
key->type->revoke(key);
/* set the death time to no more than the expiry time */
now = current_kernel_time();
time = now.tv_sec;
if (key->revoked_at == 0 || key->revoked_at > time) {
key->revoked_at = time;
key_schedule_gc(key->revoked_at + key_gc_delay);
}
up_write(&key->sem);
}
EXPORT_SYMBOL(key_revoke);
/**
* key_invalidate - Invalidate a key.
* @key: The key to be invalidated.
*
* Mark a key as being invalidated and have it cleaned up immediately. The key
* is ignored by all searches and other operations from this point.
*/
void key_invalidate(struct key *key)
{
kenter("%d", key_serial(key));
key_check(key);
if (!test_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
down_write_nested(&key->sem, 1);
if (!test_and_set_bit(KEY_FLAG_INVALIDATED, &key->flags))
key_schedule_gc_links();
up_write(&key->sem);
}
}
EXPORT_SYMBOL(key_invalidate);
/**
* generic_key_instantiate - Simple instantiation of a key from preparsed data
* @key: The key to be instantiated
* @prep: The preparsed data to load.
*
* Instantiate a key from preparsed data. We assume we can just copy the data
* in directly and clear the old pointers.
*
* This can be pointed to directly by the key type instantiate op pointer.
*/
int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
{
int ret;
pr_devel("==>%s()\n", __func__);
ret = key_payload_reserve(key, prep->quotalen);
if (ret == 0) {
rcu_assign_keypointer(key, prep->payload.data[0]);
key->payload.data[1] = prep->payload.data[1];
key->payload.data[2] = prep->payload.data[2];
key->payload.data[3] = prep->payload.data[3];
prep->payload.data[0] = NULL;
prep->payload.data[1] = NULL;
prep->payload.data[2] = NULL;
prep->payload.data[3] = NULL;
}
pr_devel("<==%s() = %d\n", __func__, ret);
return ret;
}
EXPORT_SYMBOL(generic_key_instantiate);
/**
* 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)
{
struct key_type *p;
int ret;
memset(&ktype->lock_class, 0, sizeof(ktype->lock_class));
ret = -EEXIST;
down_write(&key_types_sem);
/* disallow key types with the same name */
list_for_each_entry(p, &key_types_list, link) {
if (strcmp(p->name, ktype->name) == 0)
goto out;
}
/* store the type */
list_add(&ktype->link, &key_types_list);
pr_notice("Key type %s registered\n", ktype->name);
ret = 0;
out:
up_write(&key_types_sem);
return ret;
}
EXPORT_SYMBOL(register_key_type);
/**
* 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)
{
down_write(&key_types_sem);
list_del_init(&ktype->link);
downgrade_write(&key_types_sem);
key_gc_keytype(ktype);
pr_notice("Key type %s unregistered\n", ktype->name);
up_read(&key_types_sem);
}
EXPORT_SYMBOL(unregister_key_type);
/*
* Initialise the key management state.
*/
void __init key_init(void)
{
/* allocate a slab in which we can store keys */
key_jar = kmem_cache_create("key_jar", sizeof(struct key),
0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
/* add the special key types */
list_add_tail(&key_type_keyring.link, &key_types_list);
list_add_tail(&key_type_dead.link, &key_types_list);
list_add_tail(&key_type_user.link, &key_types_list);
list_add_tail(&key_type_logon.link, &key_types_list);
/* record the root user tracking */
rb_link_node(&root_key_user.node,
NULL,
&key_user_tree.rb_node);
rb_insert_color(&root_key_user.node,
&key_user_tree);
}