netlabel: Add functionality to set the security attributes of a packet

This patch builds upon the new NetLabel address selector functionality by
providing the NetLabel KAPI and CIPSO engine support needed to enable the
new packet-based labeling.  The only new addition to the NetLabel KAPI at
this point is shown below:

 * int netlbl_skbuff_setattr(skb, family, secattr)

... and is designed to be called from a Netfilter hook after the packet's
IP header has been populated such as in the FORWARD or LOCAL_OUT hooks.

This patch also provides the necessary SELinux hooks to support this new
functionality.  Smack support is not currently included due to uncertainty
regarding the permissions needed to expand the Smack network access controls.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Reviewed-by: James Morris <jmorris@namei.org>

1 files changed, 49 insertions, 1 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index a91146a6b37d..7432bdd5d367 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -4407,13 +4407,15 @@ static unsigned int selinux_ip_forward(struct sk_buff *skb, int ifindex,
         u32 peer_sid;
         struct avc_audit_data ad;
         u8 secmark_active;
+        u8 netlbl_active;
         u8 peerlbl_active;
 
         if (!selinux_policycap_netpeer)
                 return NF_ACCEPT;
 
         secmark_active = selinux_secmark_enabled();
-        peerlbl_active = netlbl_enabled() || selinux_xfrm_enabled();
+        netlbl_active = netlbl_enabled();
+        peerlbl_active = netlbl_active || selinux_xfrm_enabled();
         if (!secmark_active && !peerlbl_active)
                 return NF_ACCEPT;
 
@@ -4440,6 +4442,14 @@ static unsigned int selinux_ip_forward(struct sk_buff *skb, int ifindex,
                                  SECCLASS_PACKET, PACKET__FORWARD_IN, &ad))
                         return NF_DROP;
 
+        if (netlbl_active)
+                /* we do this in the FORWARD path and not the POST_ROUTING
+                 * path because we want to make sure we apply the necessary
+                 * labeling before IPsec is applied so we can leverage AH
+                 * protection */
+                if (selinux_netlbl_skbuff_setsid(skb, family, peer_sid) != 0)
+                        return NF_DROP;
+
         return NF_ACCEPT;
 }
 
@@ -4463,6 +4473,37 @@ static unsigned int selinux_ipv6_forward(unsigned int hooknum,
 }
 #endif  /* IPV6 */
 
+static unsigned int selinux_ip_output(struct sk_buff *skb,
+                                      u16 family)
+{
+        u32 sid;
+
+        if (!netlbl_enabled())
+                return NF_ACCEPT;
+
+        /* we do this in the LOCAL_OUT path and not the POST_ROUTING path
+         * because we want to make sure we apply the necessary labeling
+         * before IPsec is applied so we can leverage AH protection */
+        if (skb->sk) {
+                struct sk_security_struct *sksec = skb->sk->sk_security;
+                sid = sksec->sid;
+        } else
+                sid = SECINITSID_KERNEL;
+        if (selinux_netlbl_skbuff_setsid(skb, family, sid) != 0)
+                return NF_DROP;
+
+        return NF_ACCEPT;
+}
+
+static unsigned int selinux_ipv4_output(unsigned int hooknum,
+                                        struct sk_buff *skb,
+                                        const struct net_device *in,
+                                        const struct net_device *out,
+                                        int (*okfn)(struct sk_buff *))
+{
+        return selinux_ip_output(skb, PF_INET);
+}
+
 static int selinux_ip_postroute_iptables_compat(struct sock *sk,
                                                 int ifindex,
                                                 struct avc_audit_data *ad,
@@ -5700,6 +5741,13 @@ static struct nf_hook_ops selinux_ipv4_ops[] = {
                 .pf =           PF_INET,
                 .hooknum =      NF_INET_FORWARD,
                 .priority =     NF_IP_PRI_SELINUX_FIRST,
+        },
+        {
+                .hook =         selinux_ipv4_output,
+                .owner =        THIS_MODULE,
+                .pf =           PF_INET,
+                .hooknum =      NF_INET_LOCAL_OUT,
+                .priority =     NF_IP_PRI_SELINUX_FIRST,
         }
 };