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

Using the net-internal helper __sys_socketpair() allows us to avoid the
internal calls to the sys_socketpair() 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 9ba003e92fea0a914f5555071465d1a9b147255f..dbdddf0d079ecff1c1d9180860c88f81e01eaa6d 100644 (file)
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -372,5 +372,7 @@ extern int __sys_getsockname(int fd, struct sockaddr __user *usockaddr,
                             int __user *usockaddr_len);
 extern int __sys_getpeername(int fd, struct sockaddr __user *usockaddr,
                             int __user *usockaddr_len);
+extern int __sys_socketpair(int family, int type, int protocol,
+                           int __user *usockvec);
 
 #endif /* _LINUX_SOCKET_H */

diff --git a/net/compat.c b/net/compat.c
index 74017f618eb19c6da1b35b7b2e8fe40ffb8e20e0..04db26316438542cd9b542ce156b74d1d38b8f24 100644 (file)
--- a/net/compat.c
+++ b/net/compat.c
@@ -832,7 +832,7 @@ COMPAT_SYSCALL_DEFINE2(socketcall, int, call, u32 __user *, args)
                ret = __sys_getpeername(a0, compat_ptr(a1), compat_ptr(a[2]));
                break;
        case SYS_SOCKETPAIR:
-               ret = sys_socketpair(a0, a1, a[2], compat_ptr(a[3]));
+               ret = __sys_socketpair(a0, a1, a[2], compat_ptr(a[3]));
                break;
        case SYS_SEND:
                ret = sys_send(a0, compat_ptr(a1), a[2], a[3]);

diff --git a/net/socket.c b/net/socket.c
index 007fb94832792af72c72a6e1d36f11c45f8fa6b8..5861821f46f536a01b62063a4efd1c975dc07475 100644 (file)
--- a/net/socket.c
+++ b/net/socket.c
@@ -1368,8 +1368,7 @@ SYSCALL_DEFINE3(socket, int, family, int, type, int, protocol)
  *     Create a pair of connected sockets.
  */
 
-SYSCALL_DEFINE4(socketpair, int, family, int, type, int, protocol,
-               int __user *, usockvec)
+int __sys_socketpair(int family, int type, int protocol, int __user *usockvec)
 {
        struct socket *sock1, *sock2;
        int fd1, fd2, err;
@@ -1454,6 +1453,12 @@ out:
        return err;
 }
 
+SYSCALL_DEFINE4(socketpair, int, family, int, type, int, protocol,
+               int __user *, usockvec)
+{
+       return __sys_socketpair(family, type, protocol, usockvec);
+}
+
 /*
  *     Bind a name to a socket. Nothing much to do here since it's
  *     the protocol's responsibility to handle the local address.
@@ -2521,7 +2526,7 @@ SYSCALL_DEFINE2(socketcall, int, call, unsigned long __user *, args)
                                      (int __user *)a[2]);
                break;
        case SYS_SOCKETPAIR:
-               err = sys_socketpair(a0, a1, a[2], (int __user *)a[3]);
+               err = __sys_socketpair(a0, a1, a[2], (int __user *)a[3]);
                break;
        case SYS_SEND:
                err = sys_send(a0, (void __user *)a1, a[2], a[3]);