@@ -1193,6 +1193,7 @@ struct btrfs_root {
#define BTRFS_MOUNT_NOSSD (1 << 9)
#define BTRFS_MOUNT_DISCARD (1 << 10)
#define BTRFS_MOUNT_FORCE_COMPRESS (1 << 11)
+#define BTRFS_MOUNT_USER_SUBVOL_RM_ALLOWED (1 << 12)
#define btrfs_clear_opt(o, opt) ((o) &= ~BTRFS_MOUNT_##opt)
#define btrfs_set_opt(o, opt) ((o) |= BTRFS_MOUNT_##opt)
@@ -409,6 +409,76 @@ fail:
return ret;
}
+/* copy of check_sticky in fs/namei.c()
+* It's inline, so penalty for filesystems that don't use sticky bit is
+* minimal.
+*/
+static inline int btrfs_check_sticky(struct inode *dir, struct inode *inode)
+{
+ uid_t fsuid = current_fsuid();
+
+ if (!(dir->i_mode & S_ISVTX))
+ return 0;
+ if (inode->i_uid == fsuid)
+ return 0;
+ if (dir->i_uid == fsuid)
+ return 0;
+ return !capable(CAP_FOWNER);
+}
+
+/* copy of may_delete in fs/namei.c()
+ * Check whether we can remove a link victim from directory dir, check
+ * whether the type of victim is right.
+ * 1. We can't do it if dir is read-only (done in permission())
+ * 2. We should have write and exec permissions on dir
+ * 3. We can't remove anything from append-only dir
+ * 4. We can't do anything with immutable dir (done in permission())
+ * 5. If the sticky bit on dir is set we should either
+ * a. be owner of dir, or
+ * b. be owner of victim, or
+ * c. have CAP_FOWNER capability
+ * 6. If the victim is append-only or immutable we can't do antyhing with
+ * links pointing to it.
+ * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
+ * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
+ * 9. We can't remove a root or mountpoint.
+ * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
+ * nfs_async_unlink().
+ */
+
+static int btrfs_may_delete(struct inode *dir,struct dentry *victim,int isdir)
+{
+ int error;
+
+ if (!victim->d_inode)
+ return -ENOENT;
+
+ BUG_ON(victim->d_parent->d_inode != dir);
+ audit_inode_child(victim, dir);
+
+ error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
+ if (error)
+ return error;
+ if (IS_APPEND(dir))
+ return -EPERM;
+ if (btrfs_check_sticky(dir, victim->d_inode)||
+ IS_APPEND(victim->d_inode)||
+ IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode))
+ return -EPERM;
+ if (isdir) {
+ if (!S_ISDIR(victim->d_inode->i_mode))
+ return -ENOTDIR;
+ if (IS_ROOT(victim))
+ return -EBUSY;
+ } else if (S_ISDIR(victim->d_inode->i_mode))
+ return -EISDIR;
+ if (IS_DEADDIR(dir))
+ return -ENOENT;
+ if (victim->d_flags & DCACHE_NFSFS_RENAMED)
+ return -EBUSY;
+ return 0;
+}
+
/* copy of may_create in fs/namei.c() */
static inline int btrfs_may_create(struct inode *dir, struct dentry *child)
{
@@ -1288,9 +1358,6 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
int ret;
int err = 0;
- if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
-
vol_args = memdup_user(arg, sizeof(*vol_args));
if (IS_ERR(vol_args))
return PTR_ERR(vol_args);
@@ -1320,13 +1387,51 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
}
inode = dentry->d_inode;
+ dest = BTRFS_I(inode)->root;
+ if (!capable(CAP_SYS_ADMIN)){
+ /*
+ * Regular user. Only allow this with a special mount
+ * option, when the user has write+exec access to the
+ * subvol root, and when rmdir(2) would have been
+ * allowed.
+ *
+ * Note that this is _not_ check that the subvol is
+ * empty or doesn't contain data that we wouldn't
+ * otherwise be able to delete.
+ *
+ * Users who want to delete empty subvols should try
+ * rmdir(2).
+ */
+ err = -EPERM;
+ if (!btrfs_test_opt(root, USER_SUBVOL_RM_ALLOWED))
+ goto out_dput;
+
+ /*
+ * Do not allow deletion if the parent dir is the same
+ * as the dir to be deleted. That means the ioctl
+ * must be called on the dentry referencing the root
+ * of the subvol, not a random directory contained
+ * within it.
+ */
+ err = -EINVAL;
+ if (root == dest)
+ goto out_dput;
+
+ err = inode_permission(inode, MAY_WRITE | MAY_EXEC);
+ if (err)
+ goto out_dput;
+
+ /* check if subvolume may be deleted by a non-root user */
+ err = btrfs_may_delete(dir, dentry, 1);
+ if (err)
+ goto out_dput;
+ }
+
if (inode->i_ino != BTRFS_FIRST_FREE_OBJECTID) {
err = -EINVAL;
goto out_dput;
}
- dest = BTRFS_I(inode)->root;
-
mutex_lock(&inode->i_mutex);
err = d_invalidate(dentry);
if (err)
@@ -68,7 +68,7 @@ enum {
Opt_nodatacow, Opt_max_inline, Opt_alloc_start, Opt_nobarrier, Opt_ssd,
Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl, Opt_compress,
Opt_compress_force, Opt_notreelog, Opt_ratio, Opt_flushoncommit,
- Opt_discard, Opt_err,
+ Opt_discard, Opt_user_subvol_rm_allowed, Opt_err,
};
static match_table_t tokens = {
@@ -92,6 +92,7 @@ static match_table_t tokens = {
{Opt_flushoncommit, "flushoncommit"},
{Opt_ratio, "metadata_ratio=%d"},
{Opt_discard, "discard"},
+ {Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
{Opt_err, NULL},
};
@@ -235,6 +236,9 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
case Opt_discard:
btrfs_set_opt(info->mount_opt, DISCARD);
break;
+ case Opt_user_subvol_rm_allowed:
+ btrfs_set_opt(info->mount_opt, USER_SUBVOL_RM_ALLOWED);
+ break;
case Opt_err:
printk(KERN_INFO "btrfs: unrecognized mount option "
"'%s'\n", p);