[PATCH 017/109] net: socket: add __sys_socketpair() helper; remove in-kernel call to syscall

From: Dominik Brodowski
Date: Thu Mar 29 2018 - 08:00:58 EST


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@xxxxxxxxxxxxxxxxxxxxxxxxxx

Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: netdev@xxxxxxxxxxxxxxx
Signed-off-by: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/socket.h | 2 ++
net/compat.c | 2 +-
net/socket.c | 11 ++++++++---
3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/include/linux/socket.h b/include/linux/socket.h
index 9ba003e92fea..dbdddf0d079e 100644
--- 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 74017f618eb1..04db26316438 100644
--- 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 007fb9483279..5861821f46f5 100644
--- 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 @@ SYSCALL_DEFINE4(socketpair, int, family, int, type, int, protocol,
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]);
--
2.16.3