[PATCH net-next 1/8] sock: break up sock_cmsg_snd into __sock_cmsg_snd and loop

[Soheil Hassas Yeganeh]

From: Willem de Bruijn <will...@google.com>

To process cmsg's of the SOL_SOCKET level in addition to
cmsgs of another level, protocols can call sock_cmsg_send().
This causes a double walk on the cmsghdr list, one for SOL_SOCKET
and one for the other level.

Extract the inner demultiplex logic from the loop that walks the list,
to allow having this called directly from a walker in the protocol
specific code.

Signed-off-by: Willem de Bruijn <will...@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soh...@google.com>
---
 include/net/sock.h |  2 ++
 net/core/sock.c    | 33 ++++++++++++++++++++++-----------
 2 files changed, 24 insertions(+), 11 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index 255d3e0..03772d4 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1420,6 +1420,8 @@ struct sockcm_cookie {
        u32 mark;
 };
 
+int __sock_cmsg_send(struct sock *sk, struct msghdr *msg, struct cmsghdr *cmsg,
+                    struct sockcm_cookie *sockc);
 int sock_cmsg_send(struct sock *sk, struct msghdr *msg,
                   struct sockcm_cookie *sockc);
 
diff --git a/net/core/sock.c b/net/core/sock.c
index b67b9ae..66976f8 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1866,27 +1866,38 @@ 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 cmsghdr *cmsg,
+                    struct sockcm_cookie *sockc)
+{
+       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);
+
 int sock_cmsg_send(struct sock *sk, struct msghdr *msg,
                   struct sockcm_cookie *sockc)
 {
        struct cmsghdr *cmsg;
+       int ret;
 
        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;
-               }
+               ret = __sock_cmsg_send(sk, msg, cmsg, sockc);
+               if (ret)
+                       return ret;
        }
        return 0;
 }
-- 
2.8.0.rc3.226.g39d4020