net: socket: add __sys_sendto() helper; remove in-kernel call to syscall

Using the net-internal helper __sys_sendto() allows us to avoid the
internal calls to the sys_sendto() syscall.

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: David S. Miller <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>

diff --git a/include/linux/socket.h b/include/linux/socket.h
index 40cc93b..54b85ab 100644 (file)
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -358,5 +358,8 @@ extern int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg,
 extern int __sys_recvfrom(int fd, void __user *ubuf, size_t size,
                          unsigned int flags, struct sockaddr __user *addr,
                          int __user *addr_len);
+extern int __sys_sendto(int fd, void __user *buff, size_t len,
+                       unsigned int flags, struct sockaddr __user *addr,
+                       int addr_len);
 
 #endif /* _LINUX_SOCKET_H */

diff --git a/net/compat.c b/net/compat.c
index 2d8186c..fc82982 100644 (file)
--- a/net/compat.c
+++ b/net/compat.c
@@ -838,7 +838,8 @@ COMPAT_SYSCALL_DEFINE2(socketcall, int, call, u32 __user *, args)
                ret = sys_send(a0, compat_ptr(a1), a[2], a[3]);
                break;
        case SYS_SENDTO:
-               ret = sys_sendto(a0, compat_ptr(a1), a[2], a[3], compat_ptr(a[4]), a[5]);
+               ret = __sys_sendto(a0, compat_ptr(a1), a[2], a[3],
+                                  compat_ptr(a[4]), a[5]);
                break;
        case SYS_RECV:
                ret = compat_sys_recv(a0, compat_ptr(a1), a[2], a[3]);

diff --git a/net/socket.c b/net/socket.c
index 712d99d..3f037a2 100644 (file)
--- a/net/socket.c
+++ b/net/socket.c
@@ -1711,10 +1711,8 @@ SYSCALL_DEFINE3(getpeername, int, fd, struct sockaddr __user *, usockaddr,
  *     space and check the user space data area is readable before invoking
  *     the protocol.
  */
-
-SYSCALL_DEFINE6(sendto, int, fd, void __user *, buff, size_t, len,
-               unsigned int, flags, struct sockaddr __user *, addr,
-               int, addr_len)
+int __sys_sendto(int fd, void __user *buff, size_t len, unsigned int flags,
+                struct sockaddr __user *addr,  int addr_len)
 {
        struct socket *sock;
        struct sockaddr_storage address;
@@ -1752,6 +1750,13 @@ out:
        return err;
 }
 
+SYSCALL_DEFINE6(sendto, int, fd, void __user *, buff, size_t, len,
+               unsigned int, flags, struct sockaddr __user *, addr,
+               int, addr_len)
+{
+       return __sys_sendto(fd, buff, len, flags, addr, addr_len);
+}
+
 /*
  *     Send a datagram down a socket.
  */
@@ -1759,7 +1764,7 @@ out:
 SYSCALL_DEFINE4(send, int, fd, void __user *, buff, size_t, len,
                unsigned int, flags)
 {
-       return sys_sendto(fd, buff, len, flags, NULL, 0);
+       return __sys_sendto(fd, buff, len, flags, NULL, 0);
 }
 
 /*
@@ -2484,8 +2489,8 @@ SYSCALL_DEFINE2(socketcall, int, call, unsigned long __user *, args)
                err = sys_send(a0, (void __user *)a1, a[2], a[3]);
                break;
        case SYS_SENDTO:
-               err = sys_sendto(a0, (void __user *)a1, a[2], a[3],
-                                (struct sockaddr __user *)a[4], a[5]);
+               err = __sys_sendto(a0, (void __user *)a1, a[2], a[3],
+                                  (struct sockaddr __user *)a[4], a[5]);
                break;
        case SYS_RECV:
                err = sys_recv(a0, (void __user *)a1, a[2], a[3]);