[PATCH RFC] Smack: Fix handling of IPv4 traffic received by PF_INET6 sockets

[Piotr Sawicki]

A socket which has sk_family set to PF_INET6 is able to receive not
only IPv6 but also IPv4 traffic (IPv4-mapped IPv6 addresses).

Prior to this change, the smk_skb_to_addr_ipv6() could have been
called for socket buffers containing IPv4 packets.

Signed-off-by: Piotr Sawicki <p.sawicki2 at partner.samsung.com>
---
  security/smack/smack_lsm.c | 12 ++++++++----
  1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 19de675..1315de4 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -3924,15 +3924,19 @@ static int smack_socket_sock_rcv_skb(struct sock 
*sk, struct sk_buff *skb)
      struct smack_known *skp = NULL;
      int rc = 0;
      struct smk_audit_info ad;
+    u16 family = sk->sk_family;
  #ifdef CONFIG_AUDIT
      struct lsm_network_audit net;
  #endif
  #if IS_ENABLED(CONFIG_IPV6)
      struct sockaddr_in6 sadd;
      int proto;
+
+    if (family == PF_INET6 && skb->protocol == htons(ETH_P_IP))
+        family = PF_INET;
  #endif /* CONFIG_IPV6 */

-    switch (sk->sk_family) {
+    switch (family) {
      case PF_INET:
  #ifdef CONFIG_SECURITY_SMACK_NETFILTER
          /*
@@ -3950,7 +3954,7 @@ static int smack_socket_sock_rcv_skb(struct sock 
*sk, struct sk_buff *skb)
           */
          netlbl_secattr_init(&secattr);

-        rc = netlbl_skbuff_getattr(skb, sk->sk_family, &secattr);
+        rc = netlbl_skbuff_getattr(skb, family, &secattr);
          if (rc == 0)
              skp = smack_from_secattr(&secattr, ssp);
          else
@@ -3963,7 +3967,7 @@ static int smack_socket_sock_rcv_skb(struct sock 
*sk, struct sk_buff *skb)
  #endif
  #ifdef CONFIG_AUDIT
          smk_ad_init_net(&ad, __func__, LSM_AUDIT_DATA_NET, &net);
-        ad.a.u.net->family = sk->sk_family;
+        ad.a.u.net->family = family;
          ad.a.u.net->netif = skb->skb_iif;
          ipv4_skb_to_auditdata(skb, &ad.a, NULL);
  #endif
@@ -3977,7 +3981,7 @@ static int smack_socket_sock_rcv_skb(struct sock 
*sk, struct sk_buff *skb)
          rc = smk_bu_note("IPv4 delivery", skp, ssp->smk_in,
                      MAY_WRITE, rc);
          if (rc != 0)
-            netlbl_skbuff_err(skb, sk->sk_family, rc, 0);
+            netlbl_skbuff_err(skb, family, rc, 0);
          break;
  #if IS_ENABLED(CONFIG_IPV6)
      case PF_INET6:
-- 
2.7.4
--
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