[PATCH 011/109] net: socket: add __sys_socket() helper; remove in-kernel call to syscall

From: Dominik Brodowski
Date: Thu Mar 29 2018 - 07:37:06 EST


Using the net-internal helper __sys_socket() allows us to avoid the
internal calls to the sys_socket() 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 | 1 +
net/compat.c | 2 +-
net/socket.c | 9 +++++++--
3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/include/linux/socket.h b/include/linux/socket.h
index 6a9840271676..f8d040434a13 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -363,5 +363,6 @@ extern int __sys_sendto(int fd, void __user *buff, size_t len,
int addr_len);
extern int __sys_accept4(int fd, struct sockaddr __user *upeer_sockaddr,
int __user *upeer_addrlen, int flags);
+extern int __sys_socket(int family, int type, int protocol);

#endif /* _LINUX_SOCKET_H */
diff --git a/net/compat.c b/net/compat.c
index 0ff9f7451b6f..5b3b74c5812e 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -811,7 +811,7 @@ COMPAT_SYSCALL_DEFINE2(socketcall, int, call, u32 __user *, args)

switch (call) {
case SYS_SOCKET:
- ret = sys_socket(a0, a1, a[2]);
+ ret = __sys_socket(a0, a1, a[2]);
break;
case SYS_BIND:
ret = sys_bind(a0, compat_ptr(a1), a[2]);
diff --git a/net/socket.c b/net/socket.c
index 45f6ea0d57a5..07f379e50def 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1332,7 +1332,7 @@ int sock_create_kern(struct net *net, int family, int type, int protocol, struct
}
EXPORT_SYMBOL(sock_create_kern);

-SYSCALL_DEFINE3(socket, int, family, int, type, int, protocol)
+int __sys_socket(int family, int type, int protocol)
{
int retval;
struct socket *sock;
@@ -1359,6 +1359,11 @@ SYSCALL_DEFINE3(socket, int, family, int, type, int, protocol)
return sock_map_fd(sock, flags & (O_CLOEXEC | O_NONBLOCK));
}

+SYSCALL_DEFINE3(socket, int, family, int, type, int, protocol)
+{
+ return __sys_socket(family, type, protocol);
+}
+
/*
* Create a pair of connected sockets.
*/
@@ -2463,7 +2468,7 @@ SYSCALL_DEFINE2(socketcall, int, call, unsigned long __user *, args)

switch (call) {
case SYS_SOCKET:
- err = sys_socket(a0, a1, a[2]);
+ err = __sys_socket(a0, a1, a[2]);
break;
case SYS_BIND:
err = sys_bind(a0, (struct sockaddr __user *)a1, a[2]);
--
2.16.3