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Commit 4541e805 authored by Dominik Brodowski's avatar Dominik Brodowski
Browse files

net: socket: add __sys_accept4() helper; remove in-kernel call to syscall 

Using the net-internal helper __sys_accept4() allows us to avoid the
internal calls to the sys_accept4() 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: default avatarDominik Brodowski <linux@dominikbrodowski.net>
parent 211b634b

include/linux/socket.h

+2 −0
Original line number Diff line number Diff line
@@ -361,5 +361,7 @@ extern int __sys_recvfrom(int fd, void __user *ubuf, size_t size, 
extern int __sys_sendto(int fd, void __user *buff, size_t len,

			unsigned int flags, struct sockaddr __user *addr,

			int addr_len);

extern int __sys_accept4(int fd, struct sockaddr __user *upeer_sockaddr,

			 int __user *upeer_addrlen, int flags);



#endif /* _LINUX_SOCKET_H */

net/compat.c

+2 −2
Original line number Diff line number Diff line
@@ -823,7 +823,7 @@ COMPAT_SYSCALL_DEFINE2(socketcall, int, call, u32 __user *, args) 
		ret = sys_listen(a0, a1);

		break;

	case SYS_ACCEPT:

		ret = sys_accept4(a0, compat_ptr(a1), compat_ptr(a[2]), 0);

		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]));
@@ -873,7 +873,7 @@ COMPAT_SYSCALL_DEFINE2(socketcall, int, call, u32 __user *, args) 
					  compat_ptr(a[4]));

		break;

	case SYS_ACCEPT4:

		ret = sys_accept4(a0, compat_ptr(a1), compat_ptr(a[2]), a[3]);

		ret = __sys_accept4(a0, compat_ptr(a1), compat_ptr(a[2]), a[3]);

		break;

	default:

		ret = -EINVAL;

net/socket.c

+13 −7
Original line number Diff line number Diff line
@@ -1519,8 +1519,8 @@ SYSCALL_DEFINE2(listen, int, fd, int, backlog) 
 *	clean when we restucture accept also.

 */



SYSCALL_DEFINE4(accept4, int, fd, struct sockaddr __user *, upeer_sockaddr,

		int __user *, upeer_addrlen, int, flags)

int __sys_accept4(int fd, struct sockaddr __user *upeer_sockaddr,

		  int __user *upeer_addrlen, int flags)

{

	struct socket *sock, *newsock;

	struct file *newfile;
@@ -1599,10 +1599,16 @@ SYSCALL_DEFINE4(accept4, int, fd, struct sockaddr __user *, upeer_sockaddr, 
	goto out_put;

}



SYSCALL_DEFINE4(accept4, int, fd, struct sockaddr __user *, upeer_sockaddr,

		int __user *, upeer_addrlen, int, flags)

{

	return __sys_accept4(fd, upeer_sockaddr, upeer_addrlen, flags);

}



SYSCALL_DEFINE3(accept, int, fd, struct sockaddr __user *, upeer_sockaddr,

		int __user *, upeer_addrlen)

{

	return sys_accept4(fd, upeer_sockaddr, upeer_addrlen, 0);

	return __sys_accept4(fd, upeer_sockaddr, upeer_addrlen, 0);

}



/*
@@ -2469,7 +2475,7 @@ SYSCALL_DEFINE2(socketcall, int, call, unsigned long __user *, args) 
		err = sys_listen(a0, a1);

		break;

	case SYS_ACCEPT:

		err = sys_accept4(a0, (struct sockaddr __user *)a1,

		err = __sys_accept4(a0, (struct sockaddr __user *)a1,

				    (int __user *)a[2], 0);

		break;

	case SYS_GETSOCKNAME:
@@ -2525,7 +2531,7 @@ SYSCALL_DEFINE2(socketcall, int, call, unsigned long __user *, args) 
				   (struct timespec __user *)a[4]);

		break;

	case SYS_ACCEPT4:

		err = sys_accept4(a0, (struct sockaddr __user *)a1,

		err = __sys_accept4(a0, (struct sockaddr __user *)a1,

				    (int __user *)a[2], a[3]);

		break;

	default: