Please queue up the following patch for -stable.
It fixes a security bug and should be applied to
all maintained stable versions.
From: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Date: Thu, 19 Oct 2017 20:51:10 +0800
Subject: [PATCH] ipsec: Fix aborted xfrm policy dump crash
[ Upstream commit 1137b5e2529a8f5ca8ee709288ecba3e68044df2 ]
An independent security researcher, Mohamed Ghannam, has reported
this vulnerability to Beyond Security's SecuriTeam Secure Disclosure
program.
The xfrm_dump_policy_done function expects xfrm_dump_policy to
have been called at least once or it will crash. This can be
triggered if a dump fails because the target socket's receive
buffer is full.
This patch fixes it by using the cb->start mechanism to ensure that
the initialisation is always done regardless of the buffer situation.
Fixes: 12a169e7d8f4 ("ipsec: Put dumpers on the dump list")
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
---
net/xfrm/xfrm_user.c | 25 +++++++++++++++----------
1 file changed, 15 insertions(+), 10 deletions(-)
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index b997f13..e44a0fe 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -1693,32 +1693,34 @@ static int dump_one_policy(struct xfrm_policy *xp, int dir, int count, void *ptr
static int xfrm_dump_policy_done(struct netlink_callback *cb)
{
- struct xfrm_policy_walk *walk = (struct xfrm_policy_walk *) &cb->args[1];
+ struct xfrm_policy_walk *walk = (struct xfrm_policy_walk *)cb->args;
struct net *net = sock_net(cb->skb->sk);
xfrm_policy_walk_done(walk, net);
return 0;
}
+static int xfrm_dump_policy_start(struct netlink_callback *cb)
+{
+ struct xfrm_policy_walk *walk = (struct xfrm_policy_walk *)cb->args;
+
+ BUILD_BUG_ON(sizeof(*walk) > sizeof(cb->args));
+
+ xfrm_policy_walk_init(walk, XFRM_POLICY_TYPE_ANY);
+ return 0;
+}
+
static int xfrm_dump_policy(struct sk_buff *skb, struct netlink_callback *cb)
{
struct net *net = sock_net(skb->sk);
- struct xfrm_policy_walk *walk = (struct xfrm_policy_walk *) &cb->args[1];
+ struct xfrm_policy_walk *walk = (struct xfrm_policy_walk *)cb->args;
struct xfrm_dump_info info;
- BUILD_BUG_ON(sizeof(struct xfrm_policy_walk) >
- sizeof(cb->args) - sizeof(cb->args[0]));
-
info.in_skb = cb->skb;
info.out_skb = skb;
info.nlmsg_seq = cb->nlh->nlmsg_seq;
info.nlmsg_flags = NLM_F_MULTI;
- if (!cb->args[0]) {
- cb->args[0] = 1;
- xfrm_policy_walk_init(walk, XFRM_POLICY_TYPE_ANY);
- }
-
(void) xfrm_policy_walk(net, walk, dump_one_policy, &info);
return skb->len;
@@ -2474,6 +2476,7 @@ static const struct nla_policy xfrma_spd_policy[XFRMA_SPD_MAX+1] = {
static const struct xfrm_link {
int (*doit)(struct sk_buff *, struct nlmsghdr *, struct nlattr **);
+ int (*start)(struct netlink_callback *);
int (*dump)(struct sk_buff *, struct netlink_callback *);
int (*done)(struct netlink_callback *);
const struct nla_policy *nla_pol;
@@ -2487,6 +2490,7 @@ static const struct xfrm_link {
[XFRM_MSG_NEWPOLICY - XFRM_MSG_BASE] = { .doit = xfrm_add_policy },
[XFRM_MSG_DELPOLICY - XFRM_MSG_BASE] = { .doit = xfrm_get_policy },
[XFRM_MSG_GETPOLICY - XFRM_MSG_BASE] = { .doit = xfrm_get_policy,
+ .start = xfrm_dump_policy_start,
.dump = xfrm_dump_policy,
.done = xfrm_dump_policy_done },
[XFRM_MSG_ALLOCSPI - XFRM_MSG_BASE] = { .doit = xfrm_alloc_userspi },
@@ -2539,6 +2543,7 @@ static int xfrm_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
{
struct netlink_dump_control c = {
+ .start = link->start,
.dump = link->dump,
.done = link->done,
};
--
2.7.4