/* AFS security handling
*
- * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Copyright (C) 2007, 2017 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
#include <linux/fs.h>
#include <linux/ctype.h>
#include <linux/sched.h>
+#include <linux/hashtable.h>
#include <keys/rxrpc-type.h>
#include "internal.h"
+static DEFINE_HASHTABLE(afs_permits_cache, 10);
+static DEFINE_SPINLOCK(afs_permits_lock);
+
/*
* get a key
*/
}
/*
- * dispose of a permits list
+ * Dispose of a list of permits.
*/
-void afs_zap_permits(struct rcu_head *rcu)
+static void afs_permits_rcu(struct rcu_head *rcu)
{
struct afs_permits *permits =
container_of(rcu, struct afs_permits, rcu);
- int loop;
-
- _enter("{%d}", permits->count);
+ int i;
- for (loop = permits->count - 1; loop >= 0; loop--)
- key_put(permits->permits[loop].key);
+ for (i = 0; i < permits->nr_permits; i++)
+ key_put(permits->permits[i].key);
kfree(permits);
}
/*
- * dispose of a permits list in which all the key pointers have been copied
+ * Discard a permission cache.
*/
-static void afs_dispose_of_permits(struct rcu_head *rcu)
+void afs_put_permits(struct afs_permits *permits)
{
- struct afs_permits *permits =
- container_of(rcu, struct afs_permits, rcu);
-
- _enter("{%d}", permits->count);
-
- kfree(permits);
+ if (permits && refcount_dec_and_test(&permits->usage)) {
+ spin_lock(&afs_permits_lock);
+ hash_del_rcu(&permits->hash_node);
+ spin_unlock(&afs_permits_lock);
+ call_rcu(&permits->rcu, afs_permits_rcu);
+ }
}
/*
- * get the authorising vnode - this is the specified inode itself if it's a
- * directory or it's the parent directory if the specified inode is a file or
- * symlink
- * - the caller must release the ref on the inode
+ * Clear a permit cache on callback break.
*/
-static struct afs_vnode *afs_get_auth_inode(struct afs_vnode *vnode,
- struct key *key)
+void afs_clear_permits(struct afs_vnode *vnode)
{
- struct afs_vnode *auth_vnode;
- struct inode *auth_inode;
+ struct afs_permits *permits;
- _enter("");
+ spin_lock(&vnode->lock);
+ permits = rcu_dereference_protected(vnode->permit_cache,
+ lockdep_is_held(&vnode->lock));
+ RCU_INIT_POINTER(vnode->permit_cache, NULL);
+ vnode->cb_break++;
+ spin_unlock(&vnode->lock);
- if (S_ISDIR(vnode->vfs_inode.i_mode)) {
- auth_inode = igrab(&vnode->vfs_inode);
- ASSERT(auth_inode != NULL);
- } else {
- auth_inode = afs_iget(vnode->vfs_inode.i_sb, key,
- &vnode->status.parent, NULL, NULL);
- if (IS_ERR(auth_inode))
- return ERR_CAST(auth_inode);
- }
-
- auth_vnode = AFS_FS_I(auth_inode);
- _leave(" = {%x}", auth_vnode->fid.vnode);
- return auth_vnode;
+ if (permits)
+ afs_put_permits(permits);
}
/*
- * clear the permit cache on a directory vnode
+ * Hash a list of permits. Use simple addition to make it easy to add an extra
+ * one at an as-yet indeterminate position in the list.
*/
-void afs_clear_permits(struct afs_vnode *vnode)
+static void afs_hash_permits(struct afs_permits *permits)
{
- struct afs_permits *permits;
-
- _enter("{%x:%u}", vnode->fid.vid, vnode->fid.vnode);
+ unsigned long h = permits->nr_permits;
+ int i;
- mutex_lock(&vnode->permits_lock);
- permits = vnode->permits;
- RCU_INIT_POINTER(vnode->permits, NULL);
- mutex_unlock(&vnode->permits_lock);
+ for (i = 0; i < permits->nr_permits; i++) {
+ h += (unsigned long)permits->permits[i].key / sizeof(void *);
+ h += permits->permits[i].access;
+ }
- if (permits)
- call_rcu(&permits->rcu, afs_zap_permits);
- _leave("");
+ permits->h = h;
}
/*
- * add the result obtained for a vnode to its or its parent directory's cache
- * for the key used to access it
+ * Cache the CallerAccess result obtained from doing a fileserver operation
+ * that returned a vnode status for a particular key. If a callback break
+ * occurs whilst the operation was in progress then we have to ditch the cache
+ * as the ACL *may* have changed.
*/
-void afs_cache_permit(struct afs_vnode *vnode, struct key *key, long acl_order)
+void afs_cache_permit(struct afs_vnode *vnode, struct key *key,
+ unsigned int cb_break)
{
- struct afs_permits *permits, *xpermits;
- struct afs_permit *permit;
- struct afs_vnode *auth_vnode;
- int count, loop;
+ struct afs_permits *permits, *xpermits, *replacement, *new = NULL;
+ afs_access_t caller_access = READ_ONCE(vnode->status.caller_access);
+ size_t size = 0;
+ bool changed = false;
+ int i, j;
+
+ _enter("{%x:%u},%x,%x",
+ vnode->fid.vid, vnode->fid.vnode, key_serial(key), caller_access);
+
+ rcu_read_lock();
+
+ /* Check for the common case first: We got back the same access as last
+ * time we tried and already have it recorded.
+ */
+ permits = rcu_dereference(vnode->permit_cache);
+ if (permits) {
+ if (!permits->invalidated) {
+ for (i = 0; i < permits->nr_permits; i++) {
+ if (permits->permits[i].key < key)
+ continue;
+ if (permits->permits[i].key > key)
+ break;
+ if (permits->permits[i].access != caller_access) {
+ changed = true;
+ break;
+ }
- _enter("{%x:%u},%x,%lx",
- vnode->fid.vid, vnode->fid.vnode, key_serial(key), acl_order);
+ if (cb_break != (vnode->cb_break +
+ vnode->cb_interest->server->cb_s_break)) {
+ changed = true;
+ break;
+ }
- auth_vnode = afs_get_auth_inode(vnode, key);
- if (IS_ERR(auth_vnode)) {
- _leave(" [get error %ld]", PTR_ERR(auth_vnode));
- return;
- }
+ /* The cache is still good. */
+ rcu_read_unlock();
+ return;
+ }
+ }
+
+ changed |= permits->invalidated;
+ size = permits->nr_permits;
- mutex_lock(&auth_vnode->permits_lock);
+ /* If this set of permits is now wrong, clear the permits
+ * pointer so that no one tries to use the stale information.
+ */
+ if (changed) {
+ spin_lock(&vnode->lock);
+ if (permits != rcu_access_pointer(vnode->permit_cache))
+ goto someone_else_changed_it_unlock;
+ RCU_INIT_POINTER(vnode->permit_cache, NULL);
+ spin_unlock(&vnode->lock);
+
+ afs_put_permits(permits);
+ permits = NULL;
+ size = 0;
+ }
+ }
- /* guard against a rename being detected whilst we waited for the
- * lock */
- if (memcmp(&auth_vnode->fid, &vnode->status.parent,
- sizeof(struct afs_fid)) != 0) {
- _debug("renamed");
- goto out_unlock;
+ if (cb_break != (vnode->cb_break + vnode->cb_interest->server->cb_s_break)) {
+ rcu_read_unlock();
+ goto someone_else_changed_it;
}
- /* have to be careful as the directory's callback may be broken between
- * us receiving the status we're trying to cache and us getting the
- * lock to update the cache for the status */
- if (auth_vnode->acl_order - acl_order > 0) {
- _debug("ACL changed?");
- goto out_unlock;
+ /* We need a ref on any permits list we want to copy as we'll have to
+ * drop the lock to do memory allocation.
+ */
+ if (permits && !refcount_inc_not_zero(&permits->usage)) {
+ rcu_read_unlock();
+ goto someone_else_changed_it;
}
- /* always update the anonymous mask */
- _debug("anon access %x", vnode->status.anon_access);
- auth_vnode->status.anon_access = vnode->status.anon_access;
- if (key == vnode->volume->cell->anonymous_key)
- goto out_unlock;
-
- xpermits = auth_vnode->permits;
- count = 0;
- if (xpermits) {
- /* see if the permit is already in the list
- * - if it is then we just amend the list
- */
- count = xpermits->count;
- permit = xpermits->permits;
- for (loop = count; loop > 0; loop--) {
- if (permit->key == key) {
- permit->access_mask =
- vnode->status.caller_access;
- goto out_unlock;
+ rcu_read_unlock();
+
+ /* Speculatively create a new list with the revised permission set. We
+ * discard this if we find an extant match already in the hash, but
+ * it's easier to compare with memcmp this way.
+ *
+ * We fill in the key pointers at this time, but we don't get the refs
+ * yet.
+ */
+ size++;
+ new = kzalloc(sizeof(struct afs_permits) +
+ sizeof(struct afs_permit) * size, GFP_NOFS);
+ if (!new)
+ return;
+
+ refcount_set(&new->usage, 1);
+ new->nr_permits = size;
+ i = j = 0;
+ if (permits) {
+ for (i = 0; i < permits->nr_permits; i++) {
+ if (j == i && permits->permits[i].key > key) {
+ new->permits[j].key = key;
+ new->permits[j].access = caller_access;
+ j++;
}
- permit++;
+ new->permits[j].key = permits->permits[i].key;
+ new->permits[j].access = permits->permits[i].access;
+ j++;
+ }
+ }
+
+ if (j == i) {
+ new->permits[j].key = key;
+ new->permits[j].access = caller_access;
+ }
+
+ afs_hash_permits(new);
+
+ afs_put_permits(permits);
+
+ /* Now see if the permit list we want is actually already available */
+ spin_lock(&afs_permits_lock);
+
+ hash_for_each_possible(afs_permits_cache, xpermits, hash_node, new->h) {
+ if (xpermits->h != new->h ||
+ xpermits->invalidated ||
+ xpermits->nr_permits != new->nr_permits ||
+ memcmp(xpermits->permits, new->permits,
+ new->nr_permits * sizeof(struct afs_permit)) != 0)
+ continue;
+
+ if (refcount_inc_not_zero(&xpermits->usage)) {
+ replacement = xpermits;
+ goto found;
}
+
+ break;
}
- permits = kmalloc(sizeof(*permits) + sizeof(*permit) * (count + 1),
- GFP_NOFS);
- if (!permits)
- goto out_unlock;
-
- if (xpermits)
- memcpy(permits->permits, xpermits->permits,
- count * sizeof(struct afs_permit));
-
- _debug("key %x access %x",
- key_serial(key), vnode->status.caller_access);
- permits->permits[count].access_mask = vnode->status.caller_access;
- permits->permits[count].key = key_get(key);
- permits->count = count + 1;
-
- rcu_assign_pointer(auth_vnode->permits, permits);
- if (xpermits)
- call_rcu(&xpermits->rcu, afs_dispose_of_permits);
-
-out_unlock:
- mutex_unlock(&auth_vnode->permits_lock);
- iput(&auth_vnode->vfs_inode);
- _leave("");
+ for (i = 0; i < new->nr_permits; i++)
+ key_get(new->permits[i].key);
+ hash_add_rcu(afs_permits_cache, &new->hash_node, new->h);
+ replacement = new;
+ new = NULL;
+
+found:
+ spin_unlock(&afs_permits_lock);
+
+ kfree(new);
+
+ spin_lock(&vnode->lock);
+ if (cb_break != (vnode->cb_break + vnode->cb_interest->server->cb_s_break) ||
+ permits != rcu_access_pointer(vnode->permit_cache))
+ goto someone_else_changed_it_unlock;
+ rcu_assign_pointer(vnode->permit_cache, replacement);
+ spin_unlock(&vnode->lock);
+ afs_put_permits(permits);
+ return;
+
+someone_else_changed_it_unlock:
+ spin_unlock(&vnode->lock);
+someone_else_changed_it:
+ /* Someone else changed the cache under us - don't recheck at this
+ * time.
+ */
+ return;
}
/*
afs_access_t *_access)
{
struct afs_permits *permits;
- struct afs_permit *permit;
- struct afs_vnode *auth_vnode;
- bool valid;
- int loop, ret;
+ bool valid = false;
+ int i, ret;
_enter("{%x:%u},%x",
vnode->fid.vid, vnode->fid.vnode, key_serial(key));
- auth_vnode = afs_get_auth_inode(vnode, key);
- if (IS_ERR(auth_vnode)) {
- *_access = 0;
- _leave(" = %ld", PTR_ERR(auth_vnode));
- return PTR_ERR(auth_vnode);
- }
-
- ASSERT(S_ISDIR(auth_vnode->vfs_inode.i_mode));
+ permits = vnode->permit_cache;
/* check the permits to see if we've got one yet */
- if (key == auth_vnode->volume->cell->anonymous_key) {
+ if (key == vnode->volume->cell->anonymous_key) {
_debug("anon");
- *_access = auth_vnode->status.anon_access;
+ *_access = vnode->status.anon_access;
valid = true;
} else {
- valid = false;
rcu_read_lock();
- permits = rcu_dereference(auth_vnode->permits);
+ permits = rcu_dereference(vnode->permit_cache);
if (permits) {
- permit = permits->permits;
- for (loop = permits->count; loop > 0; loop--) {
- if (permit->key == key) {
- _debug("found in cache");
- *_access = permit->access_mask;
- valid = true;
+ for (i = 0; i < permits->nr_permits; i++) {
+ if (permits->permits[i].key < key)
+ continue;
+ if (permits->permits[i].key > key)
break;
- }
- permit++;
+
+ *_access = permits->permits[i].access;
+ valid = !permits->invalidated;
+ break;
}
}
rcu_read_unlock();
}
if (!valid) {
- /* check the status on the file we're actually interested in
- * (the post-processing will cache the result on auth_vnode) */
+ /* Check the status on the file we're actually interested in
+ * (the post-processing will cache the result).
+ */
_debug("no valid permit");
- set_bit(AFS_VNODE_CB_BROKEN, &vnode->flags);
- ret = afs_vnode_fetch_status(vnode, auth_vnode, key);
+ ret = afs_fetch_status(vnode, key);
if (ret < 0) {
- iput(&auth_vnode->vfs_inode);
*_access = 0;
_leave(" = %d", ret);
return ret;
*_access = vnode->status.caller_access;
}
- iput(&auth_vnode->vfs_inode);
_leave(" = 0 [access %x]", *_access);
return 0;
}
return PTR_ERR(key);
}
- /* if the promise has expired, we need to check the server again */
- if (!vnode->cb_promised) {
- _debug("not promised");
- ret = afs_vnode_fetch_status(vnode, NULL, key);
- if (ret < 0)
- goto error;
- _debug("new promise [fl=%lx]", vnode->flags);
- }
+ ret = afs_validate(vnode, key);
+ if (ret < 0)
+ goto error;
/* check the permits to see if we've got one yet */
ret = afs_check_permit(vnode, key, &access);
_leave(" = %d", ret);
return ret;
}
+
+void __exit afs_clean_up_permit_cache(void)
+{
+ int i;
+
+ for (i = 0; i < HASH_SIZE(afs_permits_cache); i++)
+ WARN_ON_ONCE(!hlist_empty(&afs_permits_cache[i]));
+
+}
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