This is a note to let you know that I've just added the patch titled
userns: limit the maximum depth of user_namespace->parent chain
to the 3.10-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:
userns-limit-the-maximum-depth-of-user_namespace-parent-chain.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 8742f229b635bf1c1c84a3dfe5e47c814c20b5c8 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Date: Thu, 8 Aug 2013 18:55:32 +0200
Subject: userns: limit the maximum depth of user_namespace->parent chain
From: Oleg Nesterov <oleg@xxxxxxxxxx>
commit 8742f229b635bf1c1c84a3dfe5e47c814c20b5c8 upstream.
Ensure that user_namespace->parent chain can't grow too much.
Currently we use the hardroded 32 as limit.
Reported-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/linux/user_namespace.h | 1 +
kernel/user_namespace.c | 4 ++++
2 files changed, 5 insertions(+)
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -23,6 +23,7 @@ struct user_namespace {
struct uid_gid_map projid_map;
atomic_t count;
struct user_namespace *parent;
+ int level;
kuid_t owner;
kgid_t group;
unsigned int proc_inum;
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -62,6 +62,9 @@ int create_user_ns(struct cred *new)
kgid_t group = new->egid;
int ret;
+ if (parent_ns->level > 32)
+ return -EUSERS;
+
/*
* Verify that we can not violate the policy of which files
* may be accessed that is specified by the root directory,
@@ -92,6 +95,7 @@ int create_user_ns(struct cred *new)
atomic_set(&ns->count, 1);
/* Leave the new->user_ns reference with the new user namespace. */
ns->parent = parent_ns;
+ ns->level = parent_ns->level + 1;
ns->owner = owner;
ns->group = group;
Patches currently in stable-queue which might be from oleg@xxxxxxxxxx are
queue-3.10/userns-limit-the-maximum-depth-of-user_namespace-parent-chain.patch
queue-3.10/userns-unshare_userns-cred-should-not-populate-cred-on-failure.patch
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