Using the net-internal helper __sys_getsockname() allows us to avoid the
internal calls to the sys_getsockname() 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.ga17...@light.dominikbrodowski.net

Cc: David S. Miller <da...@davemloft.net>
Cc: net...@vger.kernel.org
Signed-off-by: Dominik Brodowski <li...@dominikbrodowski.net>
---
 include/linux/socket.h |  2 ++
 net/compat.c           |  2 +-
 net/socket.c           | 14 ++++++++++----
 3 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/include/linux/socket.h b/include/linux/socket.h
index 7e37af25509d..ef0226a61b03 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -368,5 +368,7 @@ extern int __sys_bind(int fd, struct sockaddr __user 
*umyaddr, int addrlen);
 extern int __sys_connect(int fd, struct sockaddr __user *uservaddr,
                         int addrlen);
 extern int __sys_listen(int fd, int backlog);
+extern int __sys_getsockname(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 c80cb973f383..efd28d02608c 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -826,7 +826,7 @@ COMPAT_SYSCALL_DEFINE2(socketcall, int, call, u32 __user *, 
args)
                ret = __sys_accept4(a0, compat_ptr(a1), compat_ptr(a[2]), 0);
                break;
        case SYS_GETSOCKNAME:
-               ret = sys_getsockname(a0, compat_ptr(a1), compat_ptr(a[2]));
+               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]));
diff --git a/net/socket.c b/net/socket.c
index 67d9d70a4734..b61e0d20f37b 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1675,8 +1675,8 @@ SYSCALL_DEFINE3(connect, int, fd, struct sockaddr __user 
*, uservaddr,
  *     name to user space.
  */
 
-SYSCALL_DEFINE3(getsockname, int, fd, struct sockaddr __user *, usockaddr,
-               int __user *, usockaddr_len)
+int __sys_getsockname(int fd, struct sockaddr __user *usockaddr,
+                     int __user *usockaddr_len)
 {
        struct socket *sock;
        struct sockaddr_storage address;
@@ -1701,6 +1701,12 @@ SYSCALL_DEFINE3(getsockname, int, fd, struct sockaddr 
__user *, usockaddr,
        return err;
 }
 
+SYSCALL_DEFINE3(getsockname, int, fd, struct sockaddr __user *, usockaddr,
+               int __user *, usockaddr_len)
+{
+       return __sys_getsockname(fd, usockaddr, usockaddr_len);
+}
+
 /*
  *     Get the remote address ('name') of a socket object. Move the obtained
  *     name to user space.
@@ -2500,8 +2506,8 @@ SYSCALL_DEFINE2(socketcall, int, call, unsigned long 
__user *, args)
                break;
        case SYS_GETSOCKNAME:
                err =
-                   sys_getsockname(a0, (struct sockaddr __user *)a1,
-                                   (int __user *)a[2]);
+                   __sys_getsockname(a0, (struct sockaddr __user *)a1,
+                                     (int __user *)a[2]);
                break;
        case SYS_GETPEERNAME:
                err =
-- 
2.16.3

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