Commit 1137b5e2 authored by Herbert Xu's avatar Herbert Xu Committed by Steffen Klassert
Browse files

ipsec: Fix aborted xfrm policy dump crash 



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: 12a169e7 ("ipsec: Put dumpers on the dump list")
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: default avatarSteffen Klassert <steffen.klassert@secunet.com>
parent 10a7ef33

net/xfrm/xfrm_user.c

+15 −10
Original line number Diff line number Diff line
@@ -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,

			};

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