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selinux: process labeled IPsec TCP SYN-ACK packets properly in selinux_ip_postroute()

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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 <Janak.Desai@gtri.gatech.edu>
Cc: stable@vger.kernel.org
Signed-off-by: Paul Moore <pmoore@redhat.com>
This commit is contained in:
Paul Moore 2013-12-10 14:58:01 -05:00
parent 817eff718d
commit c0828e5048
1 changed files with 38 additions and 10 deletions
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48
security/selinux/hooks.c
View file

@ -4850,22 +4850,31 @@ 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
@ -4893,6 +4902,25 @@ 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;