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-rw-r--r--fs/afs/security.c356
1 files changed, 356 insertions, 0 deletions
diff --git a/fs/afs/security.c b/fs/afs/security.c
new file mode 100644
index 00000000000..f9f424d8045
--- /dev/null
+++ b/fs/afs/security.c
@@ -0,0 +1,356 @@
+/* AFS security handling
+ *
+ * Copyright (C) 2007 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/init.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/ctype.h>
+#include <keys/rxrpc-type.h>
+#include "internal.h"
+
+/*
+ * get a key
+ */
+struct key *afs_request_key(struct afs_cell *cell)
+{
+ struct key *key;
+
+ _enter("{%x}", key_serial(cell->anonymous_key));
+
+ _debug("key %s", cell->anonymous_key->description);
+ key = request_key(&key_type_rxrpc, cell->anonymous_key->description,
+ NULL);
+ if (IS_ERR(key)) {
+ if (PTR_ERR(key) != -ENOKEY) {
+ _leave(" = %ld", PTR_ERR(key));
+ return key;
+ }
+
+ /* act as anonymous user */
+ _leave(" = {%x} [anon]", key_serial(cell->anonymous_key));
+ return key_get(cell->anonymous_key);
+ } else {
+ /* act as authorised user */
+ _leave(" = {%x} [auth]", key_serial(key));
+ return key;
+ }
+}
+
+/*
+ * dispose of a permits list
+ */
+void afs_zap_permits(struct rcu_head *rcu)
+{
+ struct afs_permits *permits =
+ container_of(rcu, struct afs_permits, rcu);
+ int loop;
+
+ _enter("{%d}", permits->count);
+
+ for (loop = permits->count - 1; loop >= 0; loop--)
+ key_put(permits->permits[loop].key);
+ kfree(permits);
+}
+
+/*
+ * dispose of a permits list in which all the key pointers have been copied
+ */
+static void afs_dispose_of_permits(struct rcu_head *rcu)
+{
+ struct afs_permits *permits =
+ container_of(rcu, struct afs_permits, rcu);
+
+ _enter("{%d}", permits->count);
+
+ kfree(permits);
+}
+
+/*
+ * 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
+ */
+static struct afs_vnode *afs_get_auth_inode(struct afs_vnode *vnode,
+ struct key *key)
+{
+ struct afs_vnode *auth_vnode;
+ struct inode *auth_inode;
+
+ _enter("");
+
+ 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_PTR(PTR_ERR(auth_inode));
+ }
+
+ auth_vnode = AFS_FS_I(auth_inode);
+ _leave(" = {%x}", auth_vnode->fid.vnode);
+ return auth_vnode;
+}
+
+/*
+ * clear the permit cache on a directory vnode
+ */
+void afs_clear_permits(struct afs_vnode *vnode)
+{
+ struct afs_permits *permits;
+
+ _enter("{%x}", vnode->fid.vnode);
+
+ mutex_lock(&vnode->permits_lock);
+ permits = vnode->permits;
+ rcu_assign_pointer(vnode->permits, NULL);
+ mutex_unlock(&vnode->permits_lock);
+
+ if (permits)
+ call_rcu(&permits->rcu, afs_zap_permits);
+ _leave("");
+}
+
+/*
+ * add the result obtained for a vnode to its or its parent directory's cache
+ * for the key used to access it
+ */
+void afs_cache_permit(struct afs_vnode *vnode, struct key *key, long acl_order)
+{
+ struct afs_permits *permits, *xpermits;
+ struct afs_permit *permit;
+ struct afs_vnode *auth_vnode;
+ int count, loop;
+
+ _enter("{%x},%x,%lx", vnode->fid.vnode, key_serial(key), acl_order);
+
+ auth_vnode = afs_get_auth_inode(vnode, key);
+ if (IS_ERR(auth_vnode)) {
+ _leave(" [get error %ld]", PTR_ERR(auth_vnode));
+ return;
+ }
+
+ mutex_lock(&auth_vnode->permits_lock);
+
+ /* 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;
+ }
+
+ /* 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;
+ }
+
+ /* 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;
+ }
+ permit++;
+ }
+ }
+
+ permits = kmalloc(sizeof(*permits) + sizeof(*permit) * (count + 1),
+ GFP_NOFS);
+ if (!permits)
+ goto out_unlock;
+
+ 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("");
+}
+
+/*
+ * check with the fileserver to see if the directory or parent directory is
+ * permitted to be accessed with this authorisation, and if so, what access it
+ * is granted
+ */
+static int afs_check_permit(struct afs_vnode *vnode, struct key *key,
+ afs_access_t *_access)
+{
+ struct afs_permits *permits;
+ struct afs_permit *permit;
+ struct afs_vnode *auth_vnode;
+ bool valid;
+ int loop, ret;
+
+ _enter("");
+
+ 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));
+
+ /* check the permits to see if we've got one yet */
+ if (key == auth_vnode->volume->cell->anonymous_key) {
+ _debug("anon");
+ *_access = auth_vnode->status.anon_access;
+ valid = true;
+ } else {
+ valid = false;
+ rcu_read_lock();
+ permits = rcu_dereference(auth_vnode->permits);
+ 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;
+ break;
+ }
+ permit++;
+ }
+ }
+ 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) */
+ _debug("no valid permit");
+
+ set_bit(AFS_VNODE_CB_BROKEN, &vnode->flags);
+ ret = afs_vnode_fetch_status(vnode, auth_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;
+}
+
+/*
+ * check the permissions on an AFS file
+ * - AFS ACLs are attached to directories only, and a file is controlled by its
+ * parent directory's ACL
+ */
+int afs_permission(struct inode *inode, int mask, struct nameidata *nd)
+{
+ struct afs_vnode *vnode = AFS_FS_I(inode);
+ afs_access_t access;
+ struct key *key;
+ int ret;
+
+ _enter("{{%x:%x},%lx},%x,",
+ vnode->fid.vid, vnode->fid.vnode, vnode->flags, mask);
+
+ key = afs_request_key(vnode->volume->cell);
+ if (IS_ERR(key)) {
+ _leave(" = %ld [key]", PTR_ERR(key));
+ 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);
+ }
+
+ /* check the permits to see if we've got one yet */
+ ret = afs_check_permit(vnode, key, &access);
+ if (ret < 0)
+ goto error;
+
+ /* interpret the access mask */
+ _debug("REQ %x ACC %x on %s",
+ mask, access, S_ISDIR(inode->i_mode) ? "dir" : "file");
+
+ if (S_ISDIR(inode->i_mode)) {
+ if (mask & MAY_EXEC) {
+ if (!(access & AFS_ACE_LOOKUP))
+ goto permission_denied;
+ } else if (mask & MAY_READ) {
+ if (!(access & AFS_ACE_READ))
+ goto permission_denied;
+ } else if (mask & MAY_WRITE) {
+ if (!(access & (AFS_ACE_DELETE | /* rmdir, unlink, rename from */
+ AFS_ACE_INSERT | /* create, mkdir, symlink, rename to */
+ AFS_ACE_WRITE))) /* chmod */
+ goto permission_denied;
+ } else {
+ BUG();
+ }
+ } else {
+ if (!(access & AFS_ACE_LOOKUP))
+ goto permission_denied;
+ if (mask & (MAY_EXEC | MAY_READ)) {
+ if (!(access & AFS_ACE_READ))
+ goto permission_denied;
+ } else if (mask & MAY_WRITE) {
+ if (!(access & AFS_ACE_WRITE))
+ goto permission_denied;
+ }
+ }
+
+ key_put(key);
+ ret = generic_permission(inode, mask, NULL);
+ _leave(" = %d", ret);
+ return ret;
+
+permission_denied:
+ ret = -EACCES;
+error:
+ key_put(key);
+ _leave(" = %d", ret);
+ return ret;
+}
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