From 212cd0895330b775f2db49451f046a5ca4e5704b Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 5 Nov 2015 13:39:24 -0800 Subject: [PATCH] selinux: fix random read in selinux_ip_postroute_compat() In commit e446f9dfe17b ("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: ca6fb0651883 ("tcp: attach SYNACK messages to request sockets instead of listener") Signed-off-by: Eric Dumazet Reported-by: Dmitry Vyukov Cc: Paul Moore Signed-off-by: David S. Miller --- security/selinux/hooks.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 26f4039..c9b2d54 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -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; -- 2.7.4