diff options
Diffstat (limited to 'fs/afs/security.c')
| -rw-r--r-- | fs/afs/security.c | 363 |
1 files changed, 363 insertions, 0 deletions
diff --git a/fs/afs/security.c b/fs/afs/security.c new file mode 100644 index 000000000..8d010422d --- /dev/null +++ b/fs/afs/security.c @@ -0,0 +1,363 @@ +/* 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 <linux/sched.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_CAST(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:%u}", vnode->fid.vid, 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:%u},%x,%lx", + vnode->fid.vid, 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; + + 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(""); +} + +/* + * 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("{%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)); + + /* 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 afs_vnode *vnode = AFS_FS_I(inode); + afs_access_t uninitialized_var(access); + struct key *key; + int ret; + + if (mask & MAY_NOT_BLOCK) + return -ECHILD; + + _enter("{{%x:%u},%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); + _leave(" = %d", ret); + return ret; + +permission_denied: + ret = -EACCES; +error: + key_put(key); + _leave(" = %d", ret); + return ret; +} |