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

Using the net-internal helper __sys_getpeername() allows us to avoid the
internal calls to the sys_getpeername() 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 ef0226a..9ba003e 100644 (file)
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -370,5 +370,7 @@ extern int __sys_connect(int fd, struct sockaddr __user *uservaddr,
 extern int __sys_listen(int fd, int backlog);
 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);
 
 #endif /* _LINUX_SOCKET_H */

diff --git a/net/compat.c b/net/compat.c
index efd28d0..74017f6 100644 (file)
--- a/net/compat.c
+++ b/net/compat.c
@@ -829,7 +829,7 @@ COMPAT_SYSCALL_DEFINE2(socketcall, int, call, u32 __user *, args)
                ret = __sys_getsockname(a0, compat_ptr(a1), compat_ptr(a[2]));
                break;
        case SYS_GETPEERNAME:
-               ret = sys_getpeername(a0, compat_ptr(a1), compat_ptr(a[2]));
+               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]));

diff --git a/net/socket.c b/net/socket.c
index b61e0d2..007fb94 100644 (file)
--- a/net/socket.c
+++ b/net/socket.c
@@ -1712,8 +1712,8 @@ SYSCALL_DEFINE3(getsockname, int, fd, struct sockaddr __user *, usockaddr,
  *     name to user space.
  */
 
-SYSCALL_DEFINE3(getpeername, int, fd, struct sockaddr __user *, usockaddr,
-               int __user *, usockaddr_len)
+int __sys_getpeername(int fd, struct sockaddr __user *usockaddr,
+                     int __user *usockaddr_len)
 {
        struct socket *sock;
        struct sockaddr_storage address;
@@ -1738,6 +1738,12 @@ SYSCALL_DEFINE3(getpeername, int, fd, struct sockaddr __user *, usockaddr,
        return err;
 }
 
+SYSCALL_DEFINE3(getpeername, int, fd, struct sockaddr __user *, usockaddr,
+               int __user *, usockaddr_len)
+{
+       return __sys_getpeername(fd, usockaddr, usockaddr_len);
+}
+
 /*
  *     Send a datagram to a given address. We move the address into kernel
  *     space and check the user space data area is readable before invoking
@@ -2511,8 +2517,8 @@ SYSCALL_DEFINE2(socketcall, int, call, unsigned long __user *, args)
                break;
        case SYS_GETPEERNAME:
                err =
-                   sys_getpeername(a0, (struct sockaddr __user *)a1,
-                                   (int __user *)a[2]);
+                   __sys_getpeername(a0, (struct sockaddr __user *)a1,
+                                     (int __user *)a[2]);
                break;
        case SYS_SOCKETPAIR:
                err = sys_socketpair(a0, a1, a[2], (int __user *)a[3]);