mnt: Refactor the logic for mounting sysfs and proc in a user namespace

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commit 1b852bceb0 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" <ebiederm@xmission.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

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This commit is contained in:

Eric W. Biederman 2015-05-08 23:22:29 -05:00 • committed by Luis Henriques

parent b4147b6033

commit 6d4ba4fa0b

4 changed files with 10 additions and 10 deletions

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8

fs/namespace.c

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5

fs/proc/root.c

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5

fs/sysfs/mount.c

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2

include/linux/fs.h

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