From patchwork Thu Jul 23 01:57:45 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kamal Mostafa X-Patchwork-Id: 498948 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id B5B0414090B; Thu, 23 Jul 2015 11:58:07 +1000 (AEST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1ZI5lr-0006eI-Hn; Thu, 23 Jul 2015 01:58:03 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1ZI5lc-0006Tn-Ss for kernel-team@lists.ubuntu.com; Thu, 23 Jul 2015 01:57:48 +0000 Received: from 1.general.kamal.us.vpn ([10.172.68.52] helo=fourier) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.76) (envelope-from ) id 1ZI5lc-0005IR-BB; Thu, 23 Jul 2015 01:57:48 +0000 Received: from kamal by fourier with local (Exim 4.82) (envelope-from ) id 1ZI5la-0004mx-3Q; Wed, 22 Jul 2015 18:57:46 -0700 From: Kamal Mostafa To: "Eric W. Biederman" Subject: [3.13.y-ckt stable] Patch "mnt: Refactor the logic for mounting sysfs and proc in a user namespace" has been added to staging queue Date: Wed, 22 Jul 2015 18:57:45 -0700 Message-Id: <1437616665-18377-1-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 X-Extended-Stable: 3.13 Cc: Kamal Mostafa , kernel-team@lists.ubuntu.com X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com This is a note to let you know that I have just added a patch titled mnt: Refactor the logic for mounting sysfs and proc in a user namespace to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.13.y-queue This patch is scheduled to be released in version 3.13.11-ckt24. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.13.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From cd37911fca2f3dccc277855023e20d1fbd3a2761 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Fri, 8 May 2015 23:22:29 -0500 Subject: mnt: Refactor the logic for mounting sysfs and proc in a user namespace commit 1b852bceb0d111e510d1a15826ecc4a19358d512 upstream. Fresh mounts of proc and sysfs are a very special case that works very much like a bind mount. Unfortunately the current structure can not preserve the MNT_LOCK... mount flags. Therefore refactor the logic into a form that can be modified to preserve those lock bits. Add a new filesystem flag FS_USERNS_VISIBLE that requires some mount of the filesystem be fully visible in the current mount namespace, before the filesystem may be mounted. Move the logic for calling fs_fully_visible from proc and sysfs into fs/namespace.c where it has greater access to mount namespace state. Signed-off-by: "Eric W. Biederman" Signed-off-by: Kamal Mostafa --- fs/namespace.c | 8 +++++++- fs/proc/root.c | 5 +---- fs/sysfs/mount.c | 5 +---- include/linux/fs.h | 2 +- 4 files changed, 10 insertions(+), 10 deletions(-) -- 1.9.1 diff --git a/fs/namespace.c b/fs/namespace.c index 958e94a..09bc75b 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2141,6 +2141,8 @@ unlock: return err; } +static bool fs_fully_visible(struct file_system_type *fs_type); + /* * create a new mount for userspace and request it to be added into the * namespace's tree @@ -2172,6 +2174,10 @@ static int do_new_mount(struct path *path, const char *fstype, int flags, flags |= MS_NODEV; mnt_flags |= MNT_NODEV | MNT_LOCK_NODEV; } + if (type->fs_flags & FS_USERNS_VISIBLE) { + if (!fs_fully_visible(type)) + return -EPERM; + } } mnt = vfs_kern_mount(type, flags, name, data); @@ -2990,7 +2996,7 @@ bool current_chrooted(void) return chrooted; } -bool fs_fully_visible(struct file_system_type *type) +static bool fs_fully_visible(struct file_system_type *type) { struct mnt_namespace *ns = current->nsproxy->mnt_ns; struct mount *mnt; diff --git a/fs/proc/root.c b/fs/proc/root.c index 87dbcbe..af81d10 100644 --- a/fs/proc/root.c +++ b/fs/proc/root.c @@ -110,9 +110,6 @@ static struct dentry *proc_mount(struct file_system_type *fs_type, ns = task_active_pid_ns(current); options = data; - if (!capable(CAP_SYS_ADMIN) && !fs_fully_visible(fs_type)) - return ERR_PTR(-EPERM); - /* Does the mounter have privilege over the pid namespace? */ if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN)) return ERR_PTR(-EPERM); @@ -155,7 +152,7 @@ static struct file_system_type proc_fs_type = { .name = "proc", .mount = proc_mount, .kill_sb = proc_kill_sb, - .fs_flags = FS_USERNS_MOUNT, + .fs_flags = FS_USERNS_VISIBLE | FS_USERNS_MOUNT, }; void __init proc_root_init(void) diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c index 834ec2c..f4d0799 100644 --- a/fs/sysfs/mount.c +++ b/fs/sysfs/mount.c @@ -113,9 +113,6 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type, int error; if (!(flags & MS_KERNMOUNT)) { - if (!capable(CAP_SYS_ADMIN) && !fs_fully_visible(fs_type)) - return ERR_PTR(-EPERM); - for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++) { if (!kobj_ns_current_may_mount(type)) return ERR_PTR(-EPERM); @@ -160,7 +157,7 @@ static struct file_system_type sysfs_fs_type = { .name = "sysfs", .mount = sysfs_mount, .kill_sb = sysfs_kill_sb, - .fs_flags = FS_USERNS_MOUNT, + .fs_flags = FS_USERNS_VISIBLE | FS_USERNS_MOUNT, }; int __init sysfs_init(void) diff --git a/include/linux/fs.h b/include/linux/fs.h index 121f11f..a917265 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1815,6 +1815,7 @@ struct file_system_type { #define FS_HAS_SUBTYPE 4 #define FS_USERNS_MOUNT 8 /* Can be mounted by userns root */ #define FS_USERNS_DEV_MOUNT 16 /* A userns mount does not imply MNT_NODEV */ +#define FS_USERNS_VISIBLE 32 /* FS must already be visible */ #define FS_RENAME_DOES_D_MOVE 32768 /* FS will handle d_move() during rename() internally. */ struct dentry *(*mount) (struct file_system_type *, int, const char *, void *); @@ -1901,7 +1902,6 @@ extern int vfs_ustat(dev_t, struct kstatfs *); extern int freeze_super(struct super_block *super); extern int thaw_super(struct super_block *super); extern bool our_mnt(struct vfsmount *mnt); -extern bool fs_fully_visible(struct file_system_type *); extern int current_umask(void);