Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 212cd089 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

selinux: fix random read in selinux_ip_postroute_compat() 



In commit e446f9df ("net: synack packets can be attached to request
sockets"), I missed one remaining case of invalid skb->sk->sk_security
access.

Dmitry Vyukov got a KASan report pointing to it.

Add selinux_skb_sk() helper that is responsible to get back to the
listener if skb is attached to a request socket, instead of
duplicating the logic.

Fixes: ca6fb065 ("tcp: attach SYNACK messages to request sockets instead of listener")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reported-by: default avatarDmitry Vyukov <dvyukov@google.com>
Cc: Paul Moore <paul@paul-moore.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 432599d7

security/selinux/hooks.c

+14 −4
Original line number Diff line number Diff line
@@ -4931,11 +4931,23 @@ static unsigned int selinux_ipv4_output(void *priv, 
	return selinux_ip_output(skb, PF_INET);

}



/* SYNACK messages might be attached to request sockets.

 * To get back to sk_security, we need to look at the listener.

 */

static struct sock *selinux_skb_sk(const struct sk_buff *skb)

{

	struct sock *sk = skb->sk;



	if (sk && sk->sk_state == TCP_NEW_SYN_RECV)

		sk = inet_reqsk(sk)->rsk_listener;

	return sk;

}



static unsigned int selinux_ip_postroute_compat(struct sk_buff *skb,

						int ifindex,

						u16 family)

{

	struct sock *sk = skb->sk;

	struct sock *sk = selinux_skb_sk(skb);

	struct sk_security_struct *sksec;

	struct common_audit_data ad;

	struct lsm_network_audit net = {0,};
@@ -4990,7 +5002,7 @@ static unsigned int selinux_ip_postroute(struct sk_buff *skb, 
	if (!secmark_active && !peerlbl_active)

		return NF_ACCEPT;



	sk = skb->sk;

	sk = selinux_skb_sk(skb);



#ifdef CONFIG_XFRM

	/* If skb->dst->xfrm is non-NULL then the packet is undergoing an IPsec
@@ -5035,8 +5047,6 @@ static unsigned int selinux_ip_postroute(struct sk_buff *skb, 
		u32 skb_sid;

		struct sk_security_struct *sksec;



		if (sk->sk_state == TCP_NEW_SYN_RECV)

			sk = inet_reqsk(sk)->rsk_listener;

		sksec = sk->sk_security;

		if (selinux_skb_peerlbl_sid(skb, family, &skb_sid))

			return NF_DROP;