The patch titled
unprivileged mounts: add "no submounts" flag
has been added to the -mm tree. Its filename is
unprivileged-mounts-add-no-submounts-flag.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: unprivileged mounts: add "no submounts" flag
From: Miklos Szeredi <mszeredi@xxxxxxx>
Add a new mount flag "nomnt", which denies submounts for the owner.
This would be useful, if we want to support traditional /etc/fstab
based user mounts.
In this case mount(8) would still have to be suid-root, to check the
mountpoint against the user/users flag in /etc/fstab, but /etc/mtab
would no longer be mandatory for storing the actual owner of the
mount.
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx>
Cc: Ram Pai <linuxram@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/namespace.c | 8 +++++++-
include/linux/fs.h | 1 +
include/linux/mount.h | 1 +
3 files changed, 9 insertions(+), 1 deletion(-)
diff -puN fs/namespace.c~unprivileged-mounts-add-no-submounts-flag fs/namespace.c
--- a/fs/namespace.c~unprivileged-mounts-add-no-submounts-flag
+++ a/fs/namespace.c
@@ -441,6 +441,7 @@ static int show_vfsmnt(struct seq_file *
{ MNT_NOATIME, ",noatime" },
{ MNT_NODIRATIME, ",nodiratime" },
{ MNT_RELATIME, ",relatime" },
+ { MNT_NOMNT, ",nomnt" },
{ 0, NULL }
};
struct proc_fs_info *fs_infop;
@@ -787,6 +788,9 @@ static bool permit_mount(struct nameidat
if (S_ISLNK(inode->i_mode))
return false;
+ if (nd->mnt->mnt_flags & MNT_NOMNT)
+ return false;
+
if (!is_mount_owner(nd->mnt, current->fsuid))
return false;
@@ -1556,9 +1560,11 @@ long do_mount(char *dev_name, char *dir_
mnt_flags |= MNT_NODIRATIME;
if (flags & MS_RELATIME)
mnt_flags |= MNT_RELATIME;
+ if (flags & MS_NOMNT)
+ mnt_flags |= MNT_NOMNT;
flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE |
- MS_NOATIME | MS_NODIRATIME | MS_RELATIME);
+ MS_NOATIME | MS_NODIRATIME | MS_RELATIME | MS_NOMNT);
/* ... and get the mountpoint */
retval = path_lookup(dir_name, LOOKUP_FOLLOW, &nd);
diff -puN include/linux/fs.h~unprivileged-mounts-add-no-submounts-flag include/linux/fs.h
--- a/include/linux/fs.h~unprivileged-mounts-add-no-submounts-flag
+++ a/include/linux/fs.h
@@ -128,6 +128,7 @@ extern int dir_notify_enable;
#define MS_SHARED (1<<20) /* change to shared */
#define MS_RELATIME (1<<21) /* Update atime relative to mtime/ctime. */
#define MS_SETUSER (1<<22) /* set mnt_uid to current user */
+#define MS_NOMNT (1<<23) /* don't allow unprivileged submounts */
#define MS_ACTIVE (1<<30)
#define MS_NOUSER (1<<31)
diff -puN include/linux/mount.h~unprivileged-mounts-add-no-submounts-flag include/linux/mount.h
--- a/include/linux/mount.h~unprivileged-mounts-add-no-submounts-flag
+++ a/include/linux/mount.h
@@ -28,6 +28,7 @@ struct mnt_namespace;
#define MNT_NOATIME 0x08
#define MNT_NODIRATIME 0x10
#define MNT_RELATIME 0x20
+#define MNT_NOMNT 0x40
#define MNT_SHRINKABLE 0x100
#define MNT_USER 0x200
_
Patches currently in -mm which might be from mszeredi@xxxxxxx are
split-mmap.patch
only-allow-nonlinear-vmas-for-ram-backed-filesystems.patch
fix-quadratic-behavior-of-shrink_dcache_parent.patch
mm-shrink-parent-dentries-when-shrinking-slab.patch
add-filesystem-subtype-support.patch
add-file-position-info-to-proc.patch
check-privileges-before-setting-mount-propagation.patch
consolidate-generic_writepages-and-mpage_writepages.patch
unprivileged-mounts-add-user-mounts-to-the-kernel.patch
unprivileged-mounts-allow-unprivileged-umount.patch
unprivileged-mounts-account-user-mounts.patch
unprivileged-mounts-propagate-error-values-from-clone_mnt.patch
unprivileged-mounts-allow-unprivileged-bind-mounts.patch
unprivileged-mounts-put-declaration-of-put_filesystem-in-fsh.patch
unprivileged-mounts-allow-unprivileged-mounts.patch
unprivileged-mounts-allow-unprivileged-fuse-mounts.patch
unprivileged-mounts-propagation-inherit-owner-from-parent.patch
unprivileged-mounts-add-no-submounts-flag.patch
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