diff options
| author | Eric W. Biederman <ebiederm@xmission.com> | 2015-05-08 23:22:29 -0500 |
|---|---|---|
| committer | Sasha Levin <sasha.levin@oracle.com> | 2015-07-12 09:49:24 -0400 |
| commit | 78ee73651f6e3f0b53ca6e00615c2ca43a57174e (patch) | |
| tree | 70b5f457655866b2bf20d5152e777985c02f790a /fs | |
| parent | 866cebe251f4fb2b435f4ecfe6d3bb4025938533 (diff) | |
mnt: Refactor the logic for mounting sysfs and proc in a user namespace
[ Upstream commit 1b852bceb0d111e510d1a15826ecc4a19358d512 ]
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.
Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/namespace.c | 8 | ||||
| -rw-r--r-- | fs/proc/root.c | 5 | ||||
| -rw-r--r-- | fs/sysfs/mount.c | 5 |
3 files changed, 9 insertions, 9 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index a19d05c4ebe5..5f014636ad1e 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2297,6 +2297,8 @@ 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 @@ -2328,6 +2330,10 @@ 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); @@ -3125,7 +3131,7 @@ 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 094e44d4a6be..9e772f1a5386 100644 --- a/fs/proc/root.c +++ b/fs/proc/root.c @@ -112,9 +112,6 @@ 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); @@ -159,7 +156,7 @@ 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 8a49486bf30c..1c6ac6fcee9f 100644 --- a/fs/sysfs/mount.c +++ b/fs/sysfs/mount.c @@ -31,9 +31,6 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type, bool new_sb; if (!(flags & MS_KERNMOUNT)) { - if (!capable(CAP_SYS_ADMIN) && !fs_fully_visible(fs_type)) - return ERR_PTR(-EPERM); - if (!kobj_ns_current_may_mount(KOBJ_NS_TYPE_NET)) return ERR_PTR(-EPERM); } @@ -58,7 +55,7 @@ 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) |