net: Introduce skb_send_sock() for sock_map

We only have skb_send_sock_locked() which requires callers
to use lock_sock(). Introduce a variant skb_send_sock()
which locks on its own, callers do not need to lock it
any more. This will save us from adding a ->sendmsg_locked
for each protocol.

To reuse the code, pass function pointers to __skb_send_sock()
and build skb_send_sock() and skb_send_sock_locked() on top.

Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20210331023237.41094-4-xiyou.wangcong@gmail.com

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index c8def85..dbf820a 100644 (file)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -3626,6 +3626,7 @@ int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
                    unsigned int flags);
 int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset,
                         int len);
+int skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, int len);
 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
 unsigned int skb_zerocopy_headlen(const struct sk_buff *from);
 int skb_zerocopy(struct sk_buff *to, struct sk_buff *from,

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index e8320b5..3ad9e84 100644 (file)
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2500,9 +2500,32 @@ int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
 }
 EXPORT_SYMBOL_GPL(skb_splice_bits);
 
-/* Send skb data on a socket. Socket must be locked. */
-int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset,
-                        int len)
+static int sendmsg_unlocked(struct sock *sk, struct msghdr *msg,
+                           struct kvec *vec, size_t num, size_t size)
+{
+       struct socket *sock = sk->sk_socket;
+
+       if (!sock)
+               return -EINVAL;
+       return kernel_sendmsg(sock, msg, vec, num, size);
+}
+
+static int sendpage_unlocked(struct sock *sk, struct page *page, int offset,
+                            size_t size, int flags)
+{
+       struct socket *sock = sk->sk_socket;
+
+       if (!sock)
+               return -EINVAL;
+       return kernel_sendpage(sock, page, offset, size, flags);
+}
+
+typedef int (*sendmsg_func)(struct sock *sk, struct msghdr *msg,
+                           struct kvec *vec, size_t num, size_t size);
+typedef int (*sendpage_func)(struct sock *sk, struct page *page, int offset,
+                            size_t size, int flags);
+static int __skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset,
+                          int len, sendmsg_func sendmsg, sendpage_func sendpage)
 {
        unsigned int orig_len = len;
        struct sk_buff *head = skb;
@@ -2522,7 +2545,8 @@ do_frag_list:
                memset(&msg, 0, sizeof(msg));
                msg.msg_flags = MSG_DONTWAIT;
 
-               ret = kernel_sendmsg_locked(sk, &msg, &kv, 1, slen);
+               ret = INDIRECT_CALL_2(sendmsg, kernel_sendmsg_locked,
+                                     sendmsg_unlocked, sk, &msg, &kv, 1, slen);
                if (ret <= 0)
                        goto error;
 
@@ -2553,9 +2577,11 @@ do_frag_list:
                slen = min_t(size_t, len, skb_frag_size(frag) - offset);
 
                while (slen) {
-                       ret = kernel_sendpage_locked(sk, skb_frag_page(frag),
-                                                    skb_frag_off(frag) + offset,
-                                                    slen, MSG_DONTWAIT);
+                       ret = INDIRECT_CALL_2(sendpage, kernel_sendpage_locked,
+                                             sendpage_unlocked, sk,
+                                             skb_frag_page(frag),
+                                             skb_frag_off(frag) + offset,
+                                             slen, MSG_DONTWAIT);
                        if (ret <= 0)
                                goto error;
 
@@ -2587,8 +2613,23 @@ out:
 error:
        return orig_len == len ? ret : orig_len - len;
 }
+
+/* Send skb data on a socket. Socket must be locked. */
+int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset,
+                        int len)
+{
+       return __skb_send_sock(sk, skb, offset, len, kernel_sendmsg_locked,
+                              kernel_sendpage_locked);
+}
 EXPORT_SYMBOL_GPL(skb_send_sock_locked);
 
+/* Send skb data on a socket. Socket must be unlocked. */
+int skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, int len)
+{
+       return __skb_send_sock(sk, skb, offset, len, sendmsg_unlocked,
+                              sendpage_unlocked);
+}
+
 /**
  *     skb_store_bits - store bits from kernel buffer to skb
  *     @skb: destination buffer