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linux-next/security/keys/key.c
Linus Torvalds 644473e9c6 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull user namespace enhancements from Eric Biederman:
 "This is a course correction for the user namespace, so that we can
  reach an inexpensive, maintainable, and reasonably complete
  implementation.

  Highlights:
   - Config guards make it impossible to enable the user namespace and
     code that has not been converted to be user namespace safe.

   - Use of the new kuid_t type ensures the if you somehow get past the
     config guards the kernel will encounter type errors if you enable
     user namespaces and attempt to compile in code whose permission
     checks have not been updated to be user namespace safe.

   - All uids from child user namespaces are mapped into the initial
     user namespace before they are processed.  Removing the need to add
     an additional check to see if the user namespace of the compared
     uids remains the same.

   - With the user namespaces compiled out the performance is as good or
     better than it is today.

   - For most operations absolutely nothing changes performance or
     operationally with the user namespace enabled.

   - The worst case performance I could come up with was timing 1
     billion cache cold stat operations with the user namespace code
     enabled.  This went from 156s to 164s on my laptop (or 156ns to
     164ns per stat operation).

   - (uid_t)-1 and (gid_t)-1 are reserved as an internal error value.
     Most uid/gid setting system calls treat these value specially
     anyway so attempting to use -1 as a uid would likely cause
     entertaining failures in userspace.

   - If setuid is called with a uid that can not be mapped setuid fails.
     I have looked at sendmail, login, ssh and every other program I
     could think of that would call setuid and they all check for and
     handle the case where setuid fails.

   - If stat or a similar system call is called from a context in which
     we can not map a uid we lie and return overflowuid.  The LFS
     experience suggests not lying and returning an error code might be
     better, but the historical precedent with uids is different and I
     can not think of anything that would break by lying about a uid we
     can't map.

   - Capabilities are localized to the current user namespace making it
     safe to give the initial user in a user namespace all capabilities.

  My git tree covers all of the modifications needed to convert the core
  kernel and enough changes to make a system bootable to runlevel 1."

Fix up trivial conflicts due to nearby independent changes in fs/stat.c

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (46 commits)
  userns:  Silence silly gcc warning.
  cred: use correct cred accessor with regards to rcu read lock
  userns: Convert the move_pages, and migrate_pages permission checks to use uid_eq
  userns: Convert cgroup permission checks to use uid_eq
  userns: Convert tmpfs to use kuid and kgid where appropriate
  userns: Convert sysfs to use kgid/kuid where appropriate
  userns: Convert sysctl permission checks to use kuid and kgids.
  userns: Convert proc to use kuid/kgid where appropriate
  userns: Convert ext4 to user kuid/kgid where appropriate
  userns: Convert ext3 to use kuid/kgid where appropriate
  userns: Convert ext2 to use kuid/kgid where appropriate.
  userns: Convert devpts to use kuid/kgid where appropriate
  userns: Convert binary formats to use kuid/kgid where appropriate
  userns: Add negative depends on entries to avoid building code that is userns unsafe
  userns: signal remove unnecessary map_cred_ns
  userns: Teach inode_capable to understand inodes whose uids map to other namespaces.
  userns: Fail exec for suid and sgid binaries with ids outside our user namespace.
  userns: Convert stat to return values mapped from kuids and kgids
  userns: Convert user specfied uids and gids in chown into kuids and kgid
  userns: Use uid_eq gid_eq helpers when comparing kuids and kgids in the vfs
  ...
2012-05-23 17:42:39 -07:00

1057 lines
27 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 <linux/user_namespace.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 = 200; /* root's key count quota */
unsigned int key_quota_root_maxbytes = 20000; /* 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(uid_t uid, struct user_namespace *user_ns)
{
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 < user->uid)
p = &(*p)->rb_left;
else if (uid > user->uid)
p = &(*p)->rb_right;
else if (user_ns < user->user_ns)
p = &(*p)->rb_left;
else if (user_ns > user->user_ns)
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->user_ns = get_user_ns(user_ns);
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);
put_user_ns(user->user_ns);
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.
*
* 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,
uid_t uid, gid_t gid, const struct cred *cred,
key_perm_t perm, unsigned long flags)
{
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) + 1;
quotalen = desclen + type->def_datalen;
/* get hold of the key tracking for this user */
user = key_user_lookup(uid, cred->user_ns);
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 == 0) ?
key_quota_root_maxkeys : key_quota_maxkeys;
unsigned maxbytes = (uid == 0) ?
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_alloc(key_jar, GFP_KERNEL);
if (!key)
goto no_memory_2;
if (desc) {
key->description = kmemdup(desc, desclen, GFP_KERNEL);
if (!key->description)
goto no_memory_3;
}
atomic_set(&key->usage, 1);
init_rwsem(&key->sem);
lockdep_set_class(&key->sem, &type->lock_class);
key->type = type;
key->user = user;
key->quotalen = quotalen;
key->datalen = type->def_datalen;
key->uid = uid;
key->gid = gid;
key->perm = perm;
key->flags = 0;
key->expiry = 0;
key->payload.data = NULL;
key->security = NULL;
if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
key->flags |= 1 << KEY_FLAG_IN_QUOTA;
memset(&key->type_data, 0, sizeof(key->type_data));
#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 = (key->user->uid == 0) ?
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,
const void *data,
size_t datalen,
struct key *keyring,
struct key *authkey,
unsigned long *_prealloc)
{
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, data, datalen);
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)
__key_link(keyring, key, _prealloc);
/* disable the authorisation key */
if (authkey)
key_revoke(authkey);
}
}
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)
{
unsigned long prealloc;
int ret;
if (keyring) {
ret = __key_link_begin(keyring, key->type, key->description,
&prealloc);
if (ret < 0)
return ret;
}
ret = __key_instantiate_and_link(key, data, datalen, keyring, authkey,
&prealloc);
if (keyring)
__key_link_end(keyring, key->type, prealloc);
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)
{
unsigned long prealloc;
struct timespec now;
int ret, awaken, link_ret = 0;
key_check(key);
key_check(keyring);
awaken = 0;
ret = -EBUSY;
if (keyring)
link_ret = __key_link_begin(keyring, key->type,
key->description, &prealloc);
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);
set_bit(KEY_FLAG_NEGATIVE, &key->flags);
set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
key->type_data.reject_error = -error;
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(keyring, key, &prealloc);
/* disable the authorisation key */
if (authkey)
key_revoke(authkey);
}
mutex_unlock(&key_construction_mutex);
if (keyring)
__key_link_end(keyring, key->type, prealloc);
/* 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))
queue_work(system_nrt_wq, &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
*/
atomic_inc(&key->usage);
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,
const void *payload, size_t plen)
{
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_WRITE);
if (ret < 0)
goto error;
ret = -EEXIST;
if (!key->type->update)
goto error;
down_write(&key->sem);
ret = key->type->update(key, payload, plen);
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)
{
unsigned long prealloc;
const struct cred *cred = current_cred();
struct key_type *ktype;
struct key *keyring, *key = NULL;
key_ref_t key_ref;
int ret;
/* look up the key type to see if it's one of the registered kernel
* types */
ktype = key_type_lookup(type);
if (IS_ERR(ktype)) {
key_ref = ERR_PTR(-ENODEV);
goto error;
}
key_ref = ERR_PTR(-EINVAL);
if (!ktype->match || !ktype->instantiate)
goto error_2;
keyring = key_ref_to_ptr(keyring_ref);
key_check(keyring);
key_ref = ERR_PTR(-ENOTDIR);
if (keyring->type != &key_type_keyring)
goto error_2;
ret = __key_link_begin(keyring, ktype, description, &prealloc);
if (ret < 0)
goto error_2;
/* if we're going to allocate a new key, we're going to have
* to modify the keyring */
ret = key_permission(keyring_ref, KEY_WRITE);
if (ret < 0) {
key_ref = ERR_PTR(ret);
goto error_3;
}
/* 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 (ktype->update) {
key_ref = __keyring_search_one(keyring_ref, ktype, description,
0);
if (!IS_ERR(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 | KEY_USR_SEARCH | KEY_USR_LINK | KEY_USR_SETATTR;
if (ktype->read)
perm |= KEY_POS_READ | KEY_USR_READ;
if (ktype == &key_type_keyring || ktype->update)
perm |= KEY_USR_WRITE;
}
/* allocate a new key */
key = key_alloc(ktype, description, cred->fsuid, cred->fsgid, cred,
perm, flags);
if (IS_ERR(key)) {
key_ref = ERR_CAST(key);
goto error_3;
}
/* instantiate it and link it into the target keyring */
ret = __key_instantiate_and_link(key, payload, plen, keyring, NULL,
&prealloc);
if (ret < 0) {
key_put(key);
key_ref = ERR_PTR(ret);
goto error_3;
}
key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
error_3:
__key_link_end(keyring, ktype, prealloc);
error_2:
key_type_put(ktype);
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, ktype, prealloc);
key_type_put(ktype);
key_ref = __key_update(key_ref, payload, plen);
goto error;
}
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 *key = key_ref_to_ptr(key_ref);
int ret;
key_check(key);
/* the key must be writable */
ret = key_permission(key_ref, KEY_WRITE);
if (ret < 0)
goto error;
/* attempt to update it if supported */
ret = -EOPNOTSUPP;
if (key->type->update) {
down_write(&key->sem);
ret = key->type->update(key, payload, plen);
if (ret == 0)
/* updating a negative key instantiates it */
clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
up_write(&key->sem);
}
error:
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);
/**
* 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);
}