netfilter: nfnetlink_queue: add security context information

This patch adds an additional attribute when sending
packet information via netlink in netfilter_queue module.
It will send additional security context data, so that
userspace applications can verify this context against
their own security databases.

Signed-off-by: Roman Kubiak <r.kubiak@samsung.com>
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/include/uapi/linux/netfilter/nfnetlink_queue.h b/include/uapi/linux/netfilter/nfnetlink_queue.h
index 8dd819e..b67a853 100644 (file)
--- a/include/uapi/linux/netfilter/nfnetlink_queue.h
+++ b/include/uapi/linux/netfilter/nfnetlink_queue.h
@@ -49,6 +49,7 @@ enum nfqnl_attr_type {
        NFQA_EXP,                       /* nf_conntrack_netlink.h */
        NFQA_UID,                       /* __u32 sk uid */
        NFQA_GID,                       /* __u32 sk gid */
+       NFQA_SECCTX,                    /* security context string */
 
        __NFQA_MAX
 };
@@ -102,7 +103,8 @@ enum nfqnl_attr_config {
 #define NFQA_CFG_F_CONNTRACK                   (1 << 1)
 #define NFQA_CFG_F_GSO                         (1 << 2)
 #define NFQA_CFG_F_UID_GID                     (1 << 3)
-#define NFQA_CFG_F_MAX                         (1 << 4)
+#define NFQA_CFG_F_SECCTX                      (1 << 4)
+#define NFQA_CFG_F_MAX                         (1 << 5)
 
 /* flags for NFQA_SKB_INFO */
 /* packet appears to have wrong checksums, but they are ok */

diff --git a/net/netfilter/nfnetlink_queue_core.c b/net/netfilter/nfnetlink_queue_core.c
index 22a5ac7..6eccf0f 100644 (file)
--- a/net/netfilter/nfnetlink_queue_core.c
+++ b/net/netfilter/nfnetlink_queue_core.c
@@ -278,6 +278,23 @@ nla_put_failure:
        return -1;
 }
 
+static u32 nfqnl_get_sk_secctx(struct sk_buff *skb, char **secdata)
+{
+       u32 seclen = 0;
+#if IS_ENABLED(CONFIG_NETWORK_SECMARK)
+       if (!skb || !sk_fullsock(skb->sk))
+               return 0;
+
+       read_lock_bh(&skb->sk->sk_callback_lock);
+
+       if (skb->secmark)
+               security_secid_to_secctx(skb->secmark, secdata, &seclen);
+
+       read_unlock_bh(&skb->sk->sk_callback_lock);
+#endif
+       return seclen;
+}
+
 static struct sk_buff *
 nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
                           struct nf_queue_entry *entry,
@@ -297,6 +314,8 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
        struct nf_conn *ct = NULL;
        enum ip_conntrack_info uninitialized_var(ctinfo);
        bool csum_verify;
+       char *secdata = NULL;
+       u32 seclen = 0;
 
        size =    nlmsg_total_size(sizeof(struct nfgenmsg))
                + nla_total_size(sizeof(struct nfqnl_msg_packet_hdr))
@@ -352,6 +371,12 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
                        + nla_total_size(sizeof(u_int32_t)));   /* gid */
        }
 
+       if ((queue->flags & NFQA_CFG_F_SECCTX) && entskb->sk) {
+               seclen = nfqnl_get_sk_secctx(entskb, &secdata);
+               if (seclen)
+                       size += nla_total_size(seclen);
+       }
+
        skb = nfnetlink_alloc_skb(net, size, queue->peer_portid,
                                  GFP_ATOMIC);
        if (!skb) {
@@ -479,6 +504,9 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
            nfqnl_put_sk_uidgid(skb, entskb->sk) < 0)
                goto nla_put_failure;
 
+       if (seclen && nla_put(skb, NFQA_SECCTX, seclen, secdata))
+               goto nla_put_failure;
+
        if (ct && nfqnl_ct_put(skb, ct, ctinfo) < 0)
                goto nla_put_failure;
 
@@ -1142,7 +1170,12 @@ nfqnl_recv_config(struct sock *ctnl, struct sk_buff *skb,
                        ret = -EOPNOTSUPP;
                        goto err_out_unlock;
                }
-
+#if !IS_ENABLED(CONFIG_NETWORK_SECMARK)
+               if (flags & mask & NFQA_CFG_F_SECCTX) {
+                       ret = -EOPNOTSUPP;
+                       goto err_out_unlock;
+               }
+#endif
                spin_lock_bh(&queue->lock);
                queue->flags &= ~mask;
                queue->flags |= flags & mask;