From 5c6c26813a209e7075baf908e3ad81c1a9d389e8 Mon Sep 17 00:00:00 2001 From: Paul Moore Date: Mon, 9 Dec 2013 16:11:53 -0500 Subject: [PATCH] selinux: process labeled IPsec TCP SYN-ACK packets properly in selinux_ip_postroute() Due to difficulty in arriving at the proper security label for TCP SYN-ACK packets in selinux_ip_postroute(), we need to check packets while/before they are undergoing XFRM transforms instead of waiting until afterwards so that we can determine the correct security label. Reported-by: Janak Desai Cc: stable@vger.kernel.org Signed-off-by: Paul Moore --- security/selinux/hooks.c | 48 +++++++++++++++++++++++++++++++--------- 1 file changed, 38 insertions(+), 10 deletions(-) diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 95cb1345257d..a98228e7b91d 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -4846,22 +4846,31 @@ static unsigned int selinux_ip_postroute(struct sk_buff *skb, int ifindex, * as fast and as clean as possible. */ if (!selinux_policycap_netpeer) return selinux_ip_postroute_compat(skb, ifindex, family); -#ifdef CONFIG_XFRM - /* If skb->dst->xfrm is non-NULL then the packet is undergoing an IPsec - * packet transformation so allow the packet to pass without any checks - * since we'll have another chance to perform access control checks - * when the packet is on it's final way out. - * NOTE: there appear to be some IPv6 multicast cases where skb->dst - * is NULL, in this case go ahead and apply access control. */ - if (skb_dst(skb) != NULL && skb_dst(skb)->xfrm != NULL) - return NF_ACCEPT; -#endif + secmark_active = selinux_secmark_enabled(); peerlbl_active = selinux_peerlbl_enabled(); if (!secmark_active && !peerlbl_active) return NF_ACCEPT; sk = skb->sk; + +#ifdef CONFIG_XFRM + /* If skb->dst->xfrm is non-NULL then the packet is undergoing an IPsec + * packet transformation so allow the packet to pass without any checks + * since we'll have another chance to perform access control checks + * when the packet is on it's final way out. + * NOTE: there appear to be some IPv6 multicast cases where skb->dst + * is NULL, in this case go ahead and apply access control. + * NOTE: if this is a local socket (skb->sk != NULL) that is in the + * TCP listening state we cannot wait until the XFRM processing + * is done as we will miss out on the SA label if we do; + * unfortunately, this means more work, but it is only once per + * connection. */ + if (skb_dst(skb) != NULL && skb_dst(skb)->xfrm != NULL && + !(sk != NULL && sk->sk_state == TCP_LISTEN)) + return NF_ACCEPT; +#endif + if (sk == NULL) { /* Without an associated socket the packet is either coming * from the kernel or it is being forwarded; check the packet @@ -4889,6 +4898,25 @@ static unsigned int selinux_ip_postroute(struct sk_buff *skb, int ifindex, struct sk_security_struct *sksec = sk->sk_security; if (selinux_skb_peerlbl_sid(skb, family, &skb_sid)) return NF_DROP; + /* At this point, if the returned skb peerlbl is SECSID_NULL + * and the packet has been through at least one XFRM + * transformation then we must be dealing with the "final" + * form of labeled IPsec packet; since we've already applied + * all of our access controls on this packet we can safely + * pass the packet. */ + if (skb_sid == SECSID_NULL) { + switch (family) { + case PF_INET: + if (IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) + return NF_ACCEPT; + break; + case PF_INET6: + if (IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) + return NF_ACCEPT; + default: + return NF_DROP_ERR(-ECONNREFUSED); + } + } if (selinux_conn_sid(sksec->sid, skb_sid, &peer_sid)) return NF_DROP; secmark_perm = PACKET__SEND;