SELinux: Fix SA selection semantics

Fix the selection of an SA for an outgoing packet to be at the same
context as the originating socket/flow. This eliminates the SELinux
policy's ability to use/sendto SAs with contexts other than the socket's.

With this patch applied, the SELinux policy will require one or more of the
following for a socket to be able to communicate with/without SAs:

1. To enable a socket to communicate without using labeled-IPSec SAs:

allow socket_t unlabeled_t:association { sendto recvfrom }

2. To enable a socket to communicate with labeled-IPSec SAs:

allow socket_t self:association { sendto };
allow socket_t peer_sa_t:association { recvfrom };

Signed-off-by: Venkat Yekkirala <vyekkirala@TrustedCS.com>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 17 insertions, 9 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 5bbd599a4471..956137baf3e7 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2889,7 +2889,8 @@ static void selinux_task_to_inode(struct task_struct *p,
 }
 
 /* Returns error only if unable to parse addresses */
-static int selinux_parse_skb_ipv4(struct sk_buff *skb, struct avc_audit_data *ad)
+static int selinux_parse_skb_ipv4(struct sk_buff *skb,
+                        struct avc_audit_data *ad, u8 *proto)
 {
         int offset, ihlen, ret = -EINVAL;
         struct iphdr _iph, *ih;
@@ -2907,6 +2908,9 @@ static int selinux_parse_skb_ipv4(struct sk_buff *skb, struct avc_audit_data *ad
         ad->u.net.v4info.daddr = ih->daddr;
         ret = 0;
 
+        if (proto)
+                *proto = ih->protocol;
+
         switch (ih->protocol) {
         case IPPROTO_TCP: {
                 struct tcphdr _tcph, *th;
@@ -2950,7 +2954,8 @@ out:
 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
 
 /* Returns error only if unable to parse addresses */
-static int selinux_parse_skb_ipv6(struct sk_buff *skb, struct avc_audit_data *ad)
+static int selinux_parse_skb_ipv6(struct sk_buff *skb,
+                        struct avc_audit_data *ad, u8 *proto)
 {
         u8 nexthdr;
         int ret = -EINVAL, offset;
@@ -2971,6 +2976,9 @@ static int selinux_parse_skb_ipv6(struct sk_buff *skb, struct avc_audit_data *ad
         if (offset < 0)
                 goto out;
 
+        if (proto)
+                *proto = nexthdr;
+
         switch (nexthdr) {
         case IPPROTO_TCP: {
                 struct tcphdr _tcph, *th;
@@ -3007,13 +3015,13 @@ out:
 #endif /* IPV6 */
 
 static int selinux_parse_skb(struct sk_buff *skb, struct avc_audit_data *ad,
-                             char **addrp, int *len, int src)
+                             char **addrp, int *len, int src, u8 *proto)
 {
         int ret = 0;
 
         switch (ad->u.net.family) {
         case PF_INET:
-                ret = selinux_parse_skb_ipv4(skb, ad);
+                ret = selinux_parse_skb_ipv4(skb, ad, proto);
                 if (ret || !addrp)
                         break;
                 *len = 4;
@@ -3023,7 +3031,7 @@ static int selinux_parse_skb(struct sk_buff *skb, struct avc_audit_data *ad,
 
 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
         case PF_INET6:
-                ret = selinux_parse_skb_ipv6(skb, ad);
+                ret = selinux_parse_skb_ipv6(skb, ad, proto);
                 if (ret || !addrp)
                         break;
                 *len = 16;
@@ -3494,7 +3502,7 @@ static int selinux_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
         ad.u.net.netif = skb->dev ? skb->dev->name : "[unknown]";
         ad.u.net.family = family;
 
-        err = selinux_parse_skb(skb, &ad, &addrp, &len, 1);
+        err = selinux_parse_skb(skb, &ad, &addrp, &len, 1, NULL);
         if (err)
                 goto out;
 
@@ -3820,6 +3828,7 @@ static unsigned int selinux_ip_postroute_last(unsigned int hooknum,
         struct avc_audit_data ad;
         struct net_device *dev = (struct net_device *)out;
         struct sk_security_struct *sksec;
+        u8 proto;
 
         sk = skb->sk;
         if (!sk)
@@ -3831,7 +3840,7 @@ static unsigned int selinux_ip_postroute_last(unsigned int hooknum,
         ad.u.net.netif = dev->name;
         ad.u.net.family = family;
 
-        err = selinux_parse_skb(skb, &ad, &addrp, &len, 0);
+        err = selinux_parse_skb(skb, &ad, &addrp, &len, 0, &proto);
         if (err)
                 goto out;
 
@@ -3845,7 +3854,7 @@ static unsigned int selinux_ip_postroute_last(unsigned int hooknum,
         if (err)
                 goto out;
 
-        err = selinux_xfrm_postroute_last(sksec->sid, skb, &ad);
+        err = selinux_xfrm_postroute_last(sksec->sid, skb, &ad, proto);
 out:
         return err ? NF_DROP : NF_ACCEPT;
 }
@@ -4764,7 +4773,6 @@ static struct security_operations selinux_ops = {
         .xfrm_state_delete_security =   selinux_xfrm_state_delete,
         .xfrm_policy_lookup =           selinux_xfrm_policy_lookup,
         .xfrm_state_pol_flow_match =    selinux_xfrm_state_pol_flow_match,
-        .xfrm_flow_state_match =        selinux_xfrm_flow_state_match,
         .xfrm_decode_session =          selinux_xfrm_decode_session,
 #endif