netfilter: nfnetlink_queue: enable classid socket info retrieval

This enables associating a socket with a v1 net_cls cgroup. Useful for
applying a per-cgroup policy when processing packets in userspace.

Signed-off-by: Eric Sage <eric_sage@apple.com>
Signed-off-by: Florian Westphal <fw@strlen.de>

diff --git a/include/uapi/linux/netfilter/nfnetlink_queue.h b/include/uapi/linux/netfilter/nfnetlink_queue.h
index ef7c97f..efcb7c0 100644 (file)
--- a/include/uapi/linux/netfilter/nfnetlink_queue.h
+++ b/include/uapi/linux/netfilter/nfnetlink_queue.h
@@ -62,6 +62,7 @@ enum nfqnl_attr_type {
        NFQA_VLAN,                      /* nested attribute: packet vlan info */
        NFQA_L2HDR,                     /* full L2 header */
        NFQA_PRIORITY,                  /* skb->priority */
+       NFQA_CGROUP_CLASSID,            /* __u32 cgroup classid */
 
        __NFQA_MAX
 };

diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
index 87a9009..e311462 100644 (file)
--- a/net/netfilter/nfnetlink_queue.c
+++ b/net/netfilter/nfnetlink_queue.c
@@ -29,6 +29,7 @@
 #include <linux/netfilter/nfnetlink_queue.h>
 #include <linux/netfilter/nf_conntrack_common.h>
 #include <linux/list.h>
+#include <linux/cgroup-defs.h>
 #include <net/sock.h>
 #include <net/tcp_states.h>
 #include <net/netfilter/nf_queue.h>
@@ -301,6 +302,19 @@ nla_put_failure:
        return -1;
 }
 
+static int nfqnl_put_sk_classid(struct sk_buff *skb, struct sock *sk)
+{
+#if IS_ENABLED(CONFIG_CGROUP_NET_CLASSID)
+       if (sk && sk_fullsock(sk)) {
+               u32 classid = sock_cgroup_classid(&sk->sk_cgrp_data);
+
+               if (classid && nla_put_be32(skb, NFQA_CGROUP_CLASSID, htonl(classid)))
+                       return -1;
+       }
+#endif
+       return 0;
+}
+
 static u32 nfqnl_get_sk_secctx(struct sk_buff *skb, char **secdata)
 {
        u32 seclen = 0;
@@ -406,6 +420,9 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
                + nla_total_size(sizeof(u_int32_t))     /* priority */
                + nla_total_size(sizeof(struct nfqnl_msg_packet_hw))
                + nla_total_size(sizeof(u_int32_t))     /* skbinfo */
+#if IS_ENABLED(CONFIG_CGROUP_NET_CLASSID)
+               + nla_total_size(sizeof(u_int32_t))     /* classid */
+#endif
                + nla_total_size(sizeof(u_int32_t));    /* cap_len */
 
        tstamp = skb_tstamp_cond(entskb, false);
@@ -599,6 +616,9 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
            nfqnl_put_sk_uidgid(skb, entskb->sk) < 0)
                goto nla_put_failure;
 
+       if (nfqnl_put_sk_classid(skb, entskb->sk) < 0)
+               goto nla_put_failure;
+
        if (seclen && nla_put(skb, NFQA_SECCTX, seclen, secdata))
                goto nla_put_failure;