This is a note to let you know that I've just added the patch titled
proc: prevent stacking filesystems on top
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
proc-prevent-stacking-filesystems-on-top.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From e54ad7f1ee263ffa5a2de9c609d58dfa27b21cd9 Mon Sep 17 00:00:00 2001
From: Jann Horn <jannh@xxxxxxxxxx>
Date: Wed, 1 Jun 2016 11:55:05 +0200
Subject: proc: prevent stacking filesystems on top
From: Jann Horn <jannh@xxxxxxxxxx>
commit e54ad7f1ee263ffa5a2de9c609d58dfa27b21cd9 upstream.
This prevents stacking filesystems (ecryptfs and overlayfs) from using
procfs as lower filesystem. There is too much magic going on inside
procfs, and there is no good reason to stack stuff on top of procfs.
(For example, procfs does access checks in VFS open handlers, and
ecryptfs by design calls open handlers from a kernel thread that doesn't
drop privileges or so.)
Signed-off-by: Jann Horn <jannh@xxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/proc/root.c | 7 +++++++
1 file changed, 7 insertions(+)
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -122,6 +122,13 @@ static struct dentry *proc_mount(struct
if (IS_ERR(sb))
return ERR_CAST(sb);
+ /*
+ * procfs isn't actually a stacking filesystem; however, there is
+ * too much magic going on inside it to permit stacking things on
+ * top of it
+ */
+ sb->s_stack_depth = FILESYSTEM_MAX_STACK_DEPTH;
+
if (!proc_parse_options(options, ns)) {
deactivate_locked_super(sb);
return ERR_PTR(-EINVAL);
Patches currently in stable-queue which might be from jannh@xxxxxxxxxx are
queue-3.14/ecryptfs-forbid-opening-files-without-mmap-handler.patch
queue-3.14/proc-prevent-stacking-filesystems-on-top.patch
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html