Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760125AbYAHLiH (ORCPT ); Tue, 8 Jan 2008 06:38:07 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754832AbYAHLhX (ORCPT ); Tue, 8 Jan 2008 06:37:23 -0500 Received: from fxip-0047f.externet.hu ([88.209.222.127]:51571 "EHLO pomaz-ex.szeredi.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753650AbYAHLhW (ORCPT ); Tue, 8 Jan 2008 06:37:22 -0500 Message-Id: <20080108113630.861045063@szeredi.hu> References: <20080108113502.184459371@szeredi.hu> User-Agent: quilt/0.45-1 Date: Tue, 08 Jan 2008 12:35:09 +0100 From: Miklos Szeredi To: akpm@linux-foundation.org, hch@infradead.org, serue@us.ibm.com, viro@ftp.linux.org.uk, ebiederm@xmission.com, kzak@redhat.com Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, containers@lists.osdl.org, util-linux-ng@vger.kernel.org Subject: [patch 7/9] unprivileged mounts: allow unprivileged fuse mounts Content-Disposition: inline; filename=unprivileged-mounts-allow-unprivileged-fuse-mounts.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2843 Lines: 91 From: Miklos Szeredi Use FS_SAFE for "fuse" fs type, but not for "fuseblk". FUSE was designed from the beginning to be safe for unprivileged users. This has also been verified in practice over many years. In addition unprivileged mounts require the parent mount to be owned by the user, which is more strict than the current userspace policy. This will enable future installations to remove the suid-root fusermount utility. Don't require the "user_id=" and "group_id=" options for unprivileged mounts, but if they are present, verify them for sanity. Disallow the "allow_other" option for unprivileged mounts. Signed-off-by: Miklos Szeredi --- Index: linux/fs/fuse/inode.c =================================================================== --- linux.orig/fs/fuse/inode.c 2008-01-03 17:13:13.000000000 +0100 +++ linux/fs/fuse/inode.c 2008-01-03 21:28:01.000000000 +0100 @@ -357,6 +357,19 @@ static int parse_fuse_opt(char *opt, str d->max_read = ~0; d->blksize = 512; + /* + * For unprivileged mounts use current uid/gid. Still allow + * "user_id" and "group_id" options for compatibility, but + * only if they match these values. + */ + if (!capable(CAP_SYS_ADMIN)) { + d->user_id = current->uid; + d->user_id_present = 1; + d->group_id = current->gid; + d->group_id_present = 1; + + } + while ((p = strsep(&opt, ",")) != NULL) { int token; int value; @@ -385,6 +398,8 @@ static int parse_fuse_opt(char *opt, str case OPT_USER_ID: if (match_int(&args[0], &value)) return 0; + if (d->user_id_present && d->user_id != value) + return 0; d->user_id = value; d->user_id_present = 1; break; @@ -392,6 +407,8 @@ static int parse_fuse_opt(char *opt, str case OPT_GROUP_ID: if (match_int(&args[0], &value)) return 0; + if (d->group_id_present && d->group_id != value) + return 0; d->group_id = value; d->group_id_present = 1; break; @@ -596,6 +613,10 @@ static int fuse_fill_super(struct super_ if (!parse_fuse_opt((char *) data, &d, is_bdev)) return -EINVAL; + /* This is a privileged option */ + if ((d.flags & FUSE_ALLOW_OTHER) && !capable(CAP_SYS_ADMIN)) + return -EPERM; + if (is_bdev) { #ifdef CONFIG_BLOCK if (!sb_set_blocksize(sb, d.blksize)) @@ -696,9 +717,9 @@ static int fuse_get_sb(struct file_syste static struct file_system_type fuse_fs_type = { .owner = THIS_MODULE, .name = "fuse", - .fs_flags = FS_HAS_SUBTYPE, .get_sb = fuse_get_sb, .kill_sb = kill_anon_super, + .fs_flags = FS_HAS_SUBTYPE | FS_SAFE, }; #ifdef CONFIG_BLOCK -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/