![David Howells](/assets/img/avatar_default.png)
unregister_key_type() has code to mark a key as dead and make it unavailable in one loop and then destroy all those unavailable key payloads in the next loop. However, the loop to mark keys dead renders the key undetectable to the second loop by changing the key type pointer also. Fix this by the following means: (1) The key code has two garbage collectors: one deletes unreferenced keys and the other alters keyrings to delete links to old dead, revoked and expired keys. They can end up holding each other up as both want to scan the key serial tree under spinlock. Combine these into a single routine. (2) Move the dead key marking, dead link removal and dead key removal into the garbage collector as a three phase process running over the three cycles of the normal garbage collection procedure. This is tracked by the KEY_GC_REAPING_DEAD_1, _2 and _3 state flags. unregister_key_type() then just unlinks the key type from the list, wakes up the garbage collector and waits for the third phase to complete. (3) Downgrade the key types sem in unregister_key_type() once it has deleted the key type from the list so that it doesn't block the keyctl() syscall. (4) Dead keys that cannot be simply removed in the third phase have their payloads destroyed with the key's semaphore write-locked to prevent interference by the keyctl() syscall. There should be no in-kernel users of dead keys of that type by the point of unregistration, though keyctl() may be holding a reference. (5) Only perform timer recalculation in the GC if the timer actually expired. If it didn't, we'll get another cycle when it goes off - and if the key that actually triggered it has been removed, it's not a problem. (6) Only garbage collect link if the timer expired or if we're doing dead key clean up phase 2. (7) As only key_garbage_collector() is permitted to use rb_erase() on the key serial tree, it doesn't need to revalidate its cursor after dropping the spinlock as the node the cursor points to must still exist in the tree. (8) Drop the spinlock in the GC if there is contention on it or if we need to reschedule. After dealing with that, get the spinlock again and resume scanning. This has been tested in the following ways: (1) Run the keyutils testsuite against it. (2) Using the AF_RXRPC and RxKAD modules to test keytype removal: Load the rxrpc_s key type: # insmod /tmp/af-rxrpc.ko # insmod /tmp/rxkad.ko Create a key (http://people.redhat.com/~dhowells/rxrpc/listen.c): # /tmp/listen & [1] 8173 Find the key: # grep rxrpc_s /proc/keys 091086e1 I--Q-- 1 perm 39390000 0 0 rxrpc_s 52:2 Link it to a session keyring, preferably one with a higher serial number: # keyctl link 0x20e36251 @s Kill the process (the key should remain as it's linked to another place): # fg /tmp/listen ^C Remove the key type: rmmod rxkad rmmod af-rxrpc This can be made a more effective test by altering the following part of the patch: if (unlikely(gc_state & KEY_GC_REAPING_DEAD_2)) { /* Make sure everyone revalidates their keys if we marked a * bunch as being dead and make sure all keyring ex-payloads * are destroyed. */ kdebug("dead sync"); synchronize_rcu(); To call synchronize_rcu() in GC phase 1 instead. That causes that the keyring's old payload content to hang around longer until it's RCU destroyed - which usually happens after GC phase 3 is complete. This allows the destroy_dead_key branch to be tested. Reported-by: Benjamin Coddington <bcodding@gmail.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: James Morris <jmorris@namei.org>
1008 lines
26 KiB
C
1008 lines
26 KiB
C
/* Basic authentication token and access key management
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*
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* Copyright (C) 2004-2008 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/poison.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/security.h>
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#include <linux/workqueue.h>
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#include <linux/random.h>
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#include <linux/err.h>
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#include <linux/user_namespace.h>
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#include "internal.h"
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struct kmem_cache *key_jar;
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struct rb_root key_serial_tree; /* tree of keys indexed by serial */
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DEFINE_SPINLOCK(key_serial_lock);
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struct rb_root key_user_tree; /* tree of quota records indexed by UID */
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DEFINE_SPINLOCK(key_user_lock);
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unsigned int key_quota_root_maxkeys = 200; /* root's key count quota */
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unsigned int key_quota_root_maxbytes = 20000; /* root's key space quota */
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unsigned int key_quota_maxkeys = 200; /* general key count quota */
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unsigned int key_quota_maxbytes = 20000; /* general key space quota */
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static LIST_HEAD(key_types_list);
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static DECLARE_RWSEM(key_types_sem);
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/* We serialise key instantiation and link */
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DEFINE_MUTEX(key_construction_mutex);
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#ifdef KEY_DEBUGGING
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void __key_check(const struct key *key)
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{
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printk("__key_check: key %p {%08x} should be {%08x}\n",
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key, key->magic, KEY_DEBUG_MAGIC);
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BUG();
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}
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#endif
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/*
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* Get the key quota record for a user, allocating a new record if one doesn't
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* already exist.
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*/
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struct key_user *key_user_lookup(uid_t uid, struct user_namespace *user_ns)
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{
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struct key_user *candidate = NULL, *user;
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struct rb_node *parent = NULL;
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struct rb_node **p;
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try_again:
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p = &key_user_tree.rb_node;
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spin_lock(&key_user_lock);
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/* search the tree for a user record with a matching UID */
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while (*p) {
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parent = *p;
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user = rb_entry(parent, struct key_user, node);
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if (uid < user->uid)
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p = &(*p)->rb_left;
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else if (uid > user->uid)
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p = &(*p)->rb_right;
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else if (user_ns < user->user_ns)
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p = &(*p)->rb_left;
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else if (user_ns > user->user_ns)
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p = &(*p)->rb_right;
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else
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goto found;
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}
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/* if we get here, we failed to find a match in the tree */
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if (!candidate) {
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/* allocate a candidate user record if we don't already have
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* one */
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spin_unlock(&key_user_lock);
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user = NULL;
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candidate = kmalloc(sizeof(struct key_user), GFP_KERNEL);
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if (unlikely(!candidate))
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goto out;
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/* the allocation may have scheduled, so we need to repeat the
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* search lest someone else added the record whilst we were
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* asleep */
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goto try_again;
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}
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/* if we get here, then the user record still hadn't appeared on the
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* second pass - so we use the candidate record */
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atomic_set(&candidate->usage, 1);
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atomic_set(&candidate->nkeys, 0);
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atomic_set(&candidate->nikeys, 0);
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candidate->uid = uid;
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candidate->user_ns = get_user_ns(user_ns);
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candidate->qnkeys = 0;
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candidate->qnbytes = 0;
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spin_lock_init(&candidate->lock);
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mutex_init(&candidate->cons_lock);
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rb_link_node(&candidate->node, parent, p);
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rb_insert_color(&candidate->node, &key_user_tree);
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spin_unlock(&key_user_lock);
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user = candidate;
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goto out;
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/* okay - we found a user record for this UID */
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found:
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atomic_inc(&user->usage);
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spin_unlock(&key_user_lock);
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kfree(candidate);
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out:
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return user;
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}
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/*
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* Dispose of a user structure
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*/
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void key_user_put(struct key_user *user)
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{
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if (atomic_dec_and_lock(&user->usage, &key_user_lock)) {
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rb_erase(&user->node, &key_user_tree);
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spin_unlock(&key_user_lock);
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put_user_ns(user->user_ns);
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kfree(user);
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}
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}
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/*
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* Allocate a serial number for a key. These are assigned randomly to avoid
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* security issues through covert channel problems.
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*/
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static inline void key_alloc_serial(struct key *key)
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{
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struct rb_node *parent, **p;
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struct key *xkey;
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/* propose a random serial number and look for a hole for it in the
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* serial number tree */
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do {
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get_random_bytes(&key->serial, sizeof(key->serial));
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key->serial >>= 1; /* negative numbers are not permitted */
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} while (key->serial < 3);
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spin_lock(&key_serial_lock);
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attempt_insertion:
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parent = NULL;
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p = &key_serial_tree.rb_node;
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while (*p) {
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parent = *p;
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xkey = rb_entry(parent, struct key, serial_node);
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if (key->serial < xkey->serial)
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p = &(*p)->rb_left;
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else if (key->serial > xkey->serial)
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p = &(*p)->rb_right;
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else
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goto serial_exists;
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}
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/* we've found a suitable hole - arrange for this key to occupy it */
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rb_link_node(&key->serial_node, parent, p);
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rb_insert_color(&key->serial_node, &key_serial_tree);
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spin_unlock(&key_serial_lock);
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return;
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/* we found a key with the proposed serial number - walk the tree from
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* that point looking for the next unused serial number */
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serial_exists:
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for (;;) {
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key->serial++;
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if (key->serial < 3) {
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key->serial = 3;
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goto attempt_insertion;
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}
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parent = rb_next(parent);
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if (!parent)
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goto attempt_insertion;
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xkey = rb_entry(parent, struct key, serial_node);
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if (key->serial < xkey->serial)
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goto attempt_insertion;
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}
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}
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/**
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* key_alloc - Allocate a key of the specified type.
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* @type: The type of key to allocate.
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* @desc: The key description to allow the key to be searched out.
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* @uid: The owner of the new key.
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* @gid: The group ID for the new key's group permissions.
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* @cred: The credentials specifying UID namespace.
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* @perm: The permissions mask of the new key.
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* @flags: Flags specifying quota properties.
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*
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* Allocate a key of the specified type with the attributes given. The key is
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* returned in an uninstantiated state and the caller needs to instantiate the
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* key before returning.
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*
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* The user's key count quota is updated to reflect the creation of the key and
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* the user's key data quota has the default for the key type reserved. The
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* instantiation function should amend this as necessary. If insufficient
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* quota is available, -EDQUOT will be returned.
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*
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* The LSM security modules can prevent a key being created, in which case
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* -EACCES will be returned.
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*
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* Returns a pointer to the new key if successful and an error code otherwise.
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*
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* Note that the caller needs to ensure the key type isn't uninstantiated.
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* Internally this can be done by locking key_types_sem. Externally, this can
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* be done by either never unregistering the key type, or making sure
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* key_alloc() calls don't race with module unloading.
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*/
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struct key *key_alloc(struct key_type *type, const char *desc,
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uid_t uid, gid_t gid, const struct cred *cred,
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key_perm_t perm, unsigned long flags)
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{
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struct key_user *user = NULL;
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struct key *key;
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size_t desclen, quotalen;
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int ret;
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key = ERR_PTR(-EINVAL);
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if (!desc || !*desc)
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goto error;
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if (type->vet_description) {
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ret = type->vet_description(desc);
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if (ret < 0) {
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key = ERR_PTR(ret);
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goto error;
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}
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}
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desclen = strlen(desc) + 1;
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quotalen = desclen + type->def_datalen;
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/* get hold of the key tracking for this user */
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user = key_user_lookup(uid, cred->user->user_ns);
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if (!user)
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goto no_memory_1;
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/* check that the user's quota permits allocation of another key and
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* its description */
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if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
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unsigned maxkeys = (uid == 0) ?
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key_quota_root_maxkeys : key_quota_maxkeys;
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unsigned maxbytes = (uid == 0) ?
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key_quota_root_maxbytes : key_quota_maxbytes;
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spin_lock(&user->lock);
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if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
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if (user->qnkeys + 1 >= maxkeys ||
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user->qnbytes + quotalen >= maxbytes ||
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user->qnbytes + quotalen < user->qnbytes)
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goto no_quota;
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}
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user->qnkeys++;
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user->qnbytes += quotalen;
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spin_unlock(&user->lock);
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}
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/* allocate and initialise the key and its description */
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key = kmem_cache_alloc(key_jar, GFP_KERNEL);
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if (!key)
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goto no_memory_2;
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if (desc) {
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key->description = kmemdup(desc, desclen, GFP_KERNEL);
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if (!key->description)
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goto no_memory_3;
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}
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atomic_set(&key->usage, 1);
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init_rwsem(&key->sem);
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key->type = type;
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key->user = user;
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key->quotalen = quotalen;
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key->datalen = type->def_datalen;
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key->uid = uid;
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key->gid = gid;
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key->perm = perm;
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key->flags = 0;
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key->expiry = 0;
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key->payload.data = NULL;
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key->security = NULL;
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if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
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key->flags |= 1 << KEY_FLAG_IN_QUOTA;
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memset(&key->type_data, 0, sizeof(key->type_data));
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#ifdef KEY_DEBUGGING
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key->magic = KEY_DEBUG_MAGIC;
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#endif
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/* let the security module know about the key */
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ret = security_key_alloc(key, cred, flags);
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if (ret < 0)
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goto security_error;
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/* publish the key by giving it a serial number */
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atomic_inc(&user->nkeys);
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key_alloc_serial(key);
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error:
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return key;
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security_error:
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kfree(key->description);
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kmem_cache_free(key_jar, key);
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if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
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spin_lock(&user->lock);
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user->qnkeys--;
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user->qnbytes -= quotalen;
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spin_unlock(&user->lock);
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}
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key_user_put(user);
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key = ERR_PTR(ret);
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goto error;
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no_memory_3:
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kmem_cache_free(key_jar, key);
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no_memory_2:
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if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
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spin_lock(&user->lock);
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user->qnkeys--;
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user->qnbytes -= quotalen;
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spin_unlock(&user->lock);
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}
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key_user_put(user);
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no_memory_1:
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key = ERR_PTR(-ENOMEM);
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goto error;
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no_quota:
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spin_unlock(&user->lock);
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key_user_put(user);
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key = ERR_PTR(-EDQUOT);
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goto error;
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}
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EXPORT_SYMBOL(key_alloc);
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/**
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* key_payload_reserve - Adjust data quota reservation for the key's payload
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* @key: The key to make the reservation for.
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* @datalen: The amount of data payload the caller now wants.
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*
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* Adjust the amount of the owning user's key data quota that a key reserves.
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* If the amount is increased, then -EDQUOT may be returned if there isn't
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* enough free quota available.
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*
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* If successful, 0 is returned.
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*/
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int key_payload_reserve(struct key *key, size_t datalen)
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{
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int delta = (int)datalen - key->datalen;
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int ret = 0;
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key_check(key);
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/* contemplate the quota adjustment */
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if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
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unsigned maxbytes = (key->user->uid == 0) ?
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key_quota_root_maxbytes : key_quota_maxbytes;
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spin_lock(&key->user->lock);
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if (delta > 0 &&
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(key->user->qnbytes + delta >= maxbytes ||
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key->user->qnbytes + delta < key->user->qnbytes)) {
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ret = -EDQUOT;
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}
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else {
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key->user->qnbytes += delta;
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key->quotalen += delta;
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}
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spin_unlock(&key->user->lock);
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}
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/* change the recorded data length if that didn't generate an error */
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if (ret == 0)
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key->datalen = datalen;
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return ret;
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}
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EXPORT_SYMBOL(key_payload_reserve);
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/*
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* Instantiate a key and link it into the target keyring atomically. Must be
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* called with the target keyring's semaphore writelocked. The target key's
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* semaphore need not be locked as instantiation is serialised by
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* key_construction_mutex.
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*/
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static int __key_instantiate_and_link(struct key *key,
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const void *data,
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size_t datalen,
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struct key *keyring,
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struct key *authkey,
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unsigned long *_prealloc)
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{
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int ret, awaken;
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key_check(key);
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key_check(keyring);
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awaken = 0;
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ret = -EBUSY;
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mutex_lock(&key_construction_mutex);
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/* can't instantiate twice */
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if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
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/* instantiate the key */
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ret = key->type->instantiate(key, data, datalen);
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if (ret == 0) {
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/* mark the key as being instantiated */
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atomic_inc(&key->user->nikeys);
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set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
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if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
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awaken = 1;
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/* and link it into the destination keyring */
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if (keyring)
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__key_link(keyring, key, _prealloc);
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/* disable the authorisation key */
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if (authkey)
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key_revoke(authkey);
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}
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}
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mutex_unlock(&key_construction_mutex);
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/* wake up anyone waiting for a key to be constructed */
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if (awaken)
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wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
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return ret;
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}
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/**
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* key_instantiate_and_link - Instantiate a key and link it into the keyring.
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* @key: The key to instantiate.
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* @data: The data to use to instantiate the keyring.
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* @datalen: The length of @data.
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* @keyring: Keyring to create a link in on success (or NULL).
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* @authkey: The authorisation token permitting instantiation.
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*
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* Instantiate a key that's in the uninstantiated state using the provided data
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|
* 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;
|
|
}
|
|
|
|
/*
|
|
* 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);
|
|
|
|
/**
|
|
* 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;
|
|
|
|
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);
|
|
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);
|
|
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);
|
|
|
|
/* 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);
|
|
}
|