sock: support per-packet fwmark

It's useful to allow users to set fwmark for an individual packet, without changing the socket state. The function this patch adds in sock layer can be used by the protocols that need such a feature. Signed-off-by: Edward Hyunkoo Jee <[email protected]> Signed-off-by: Eric Dumazet <[email protected]> Cc: Willem de Bruijn <[email protected]> Signed-off-by: David S. Miller <[email protected]>
mrcsosa · Oct 13, 2015 · f28ea36 · f28ea36
1 parent c1bf5fe
commit f28ea36
Show file tree

Hide file tree

Showing 2 changed files with 33 additions and 0 deletions.
diff --git a/include/net/sock.h b/include/net/sock.h
@@ -1514,6 +1514,13 @@ void sock_kfree_s(struct sock *sk, void *mem, int size);
 void sock_kzfree_s(struct sock *sk, void *mem, int size);
 void sk_send_sigurg(struct sock *sk);
 
+struct sockcm_cookie {
+	u32 mark;
+};
+
+int sock_cmsg_send(struct sock *sk, struct msghdr *msg,
+		   struct sockcm_cookie *sockc);
+
 /*
  * Functions to fill in entries in struct proto_ops when a protocol
  * does not implement a particular function.

diff --git a/net/core/sock.c b/net/core/sock.c
@@ -1852,6 +1852,32 @@ struct sk_buff *sock_alloc_send_skb(struct sock *sk, unsigned long size,
 }
 EXPORT_SYMBOL(sock_alloc_send_skb);
 
+int sock_cmsg_send(struct sock *sk, struct msghdr *msg,
+		   struct sockcm_cookie *sockc)
+{
+	struct cmsghdr *cmsg;
+
+	for_each_cmsghdr(cmsg, msg) {
+		if (!CMSG_OK(msg, cmsg))
+			return -EINVAL;
+		if (cmsg->cmsg_level != SOL_SOCKET)
+			continue;
+		switch (cmsg->cmsg_type) {
+		case SO_MARK:
+			if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
+				return -EPERM;
+			if (cmsg->cmsg_len != CMSG_LEN(sizeof(u32)))
+				return -EINVAL;
+			sockc->mark = *(u32 *)CMSG_DATA(cmsg);
+			break;
+		default:
+			return -EINVAL;
+		}
+	}
+	return 0;
+}
+EXPORT_SYMBOL(sock_cmsg_send);
+
 /* On 32bit arches, an skb frag is limited to 2^15 */
 #define SKB_FRAG_PAGE_ORDER	get_order(32768)