From 01b810b889d557257580970e1a7ba9c85b54766b Mon Sep 17 00:00:00 2001 From: David Sterba Date: Tue, 12 May 2015 19:14:49 +0200 Subject: [PATCH] btrfs: make root id query unprivileged The INO_LOOKUP ioctl can lookup path for a given inode number and is thus restricted. As a sideefect it can find the root id of the containing subvolume and we're using this int the 'btrfs inspect rootid' command. The restriction is unnecessary in case we set the ioctl args args::treeid = 0 args::objectid = 256 (BTRFS_FIRST_FREE_OBJECTID) Then the path will be empty and the treeid is filled with the root id of the inode on which the ioctl is called. This behaviour is unchanged, after the root restriction is removed. Signed-off-by: David Sterba Signed-off-by: Chris Mason --- fs/btrfs/ioctl.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index f77f6b3d24b9..f7c65ca056f8 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -2271,10 +2271,7 @@ static noinline int btrfs_ioctl_ino_lookup(struct file *file, { struct btrfs_ioctl_ino_lookup_args *args; struct inode *inode; - int ret; - - if (!capable(CAP_SYS_ADMIN)) - return -EPERM; + int ret = 0; args = memdup_user(argp, sizeof(*args)); if (IS_ERR(args)) @@ -2282,13 +2279,28 @@ static noinline int btrfs_ioctl_ino_lookup(struct file *file, inode = file_inode(file); + /* + * Unprivileged query to obtain the containing subvolume root id. The + * path is reset so it's consistent with btrfs_search_path_in_tree. + */ if (args->treeid == 0) args->treeid = BTRFS_I(inode)->root->root_key.objectid; + if (args->objectid == BTRFS_FIRST_FREE_OBJECTID) { + args->name[0] = 0; + goto out; + } + + if (!capable(CAP_SYS_ADMIN)) { + ret = -EPERM; + goto out; + } + ret = btrfs_search_path_in_tree(BTRFS_I(inode)->root->fs_info, args->treeid, args->objectid, args->name); +out: if (ret == 0 && copy_to_user(argp, args, sizeof(*args))) ret = -EFAULT; -- 2.20.1