linux-kernel - [PATCH -next 21/22] net: socket: add __compat_sys_recvmmsg() helper; remove in-kernel call to compat syscall

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Date:   Fri, 16 Mar 2018 18:06:13 +0100
From:   Dominik Brodowski <linux@...inikbrodowski.net>
To:     linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
        davem@...emloft.net
Cc:     netdev@...r.kernel.org
Subject: [PATCH -next 21/22] net: socket: add __compat_sys_recvmmsg() helper; remove in-kernel call to compat syscall

Using the net-internal helper __compat_sys_recvmmsg() allows us to avoid
the internal calls to the compat_sys_recvmmsg() syscall.

Cc: David S. Miller <davem@...emloft.net>
Cc: netdev@...r.kernel.org
Signed-off-by: Dominik Brodowski <linux@...inikbrodowski.net>
---
 net/compat.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/net/compat.c b/net/compat.c
index cdf5b0c1b962..7b2ae42a1598 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -787,9 +787,9 @@ COMPAT_SYSCALL_DEFINE6(recvfrom, int, fd, void __user *, buf, compat_size_t, len
 	return __compat_sys_recvfrom(fd, buf, len, flags, addr, addrlen);
 }
 
-COMPAT_SYSCALL_DEFINE5(recvmmsg, int, fd, struct compat_mmsghdr __user *, mmsg,
-		       unsigned int, vlen, unsigned int, flags,
-		       struct compat_timespec __user *, timeout)
+static int __compat_sys_recvmmsg(int fd, struct compat_mmsghdr __user *mmsg,
+				 unsigned int vlen, unsigned int flags,
+				 struct compat_timespec __user *timeout)
 {
 	int datagrams;
 	struct timespec ktspec;
@@ -809,6 +809,13 @@ COMPAT_SYSCALL_DEFINE5(recvmmsg, int, fd, struct compat_mmsghdr __user *, mmsg,
 	return datagrams;
 }
 
+COMPAT_SYSCALL_DEFINE5(recvmmsg, int, fd, struct compat_mmsghdr __user *, mmsg,
+		       unsigned int, vlen, unsigned int, flags,
+		       struct compat_timespec __user *, timeout)
+{
+	return __compat_sys_recvmmsg(fd, mmsg, vlen, flags, timeout);
+}
+
 COMPAT_SYSCALL_DEFINE2(socketcall, int, call, u32 __user *, args)
 {
 	u32 a[AUDITSC_ARGS];
@@ -895,8 +902,8 @@ COMPAT_SYSCALL_DEFINE2(socketcall, int, call, u32 __user *, args)
 		ret = compat_sys_recvmsg(a0, compat_ptr(a1), a[2]);
 		break;
 	case SYS_RECVMMSG:
-		ret = compat_sys_recvmmsg(a0, compat_ptr(a1), a[2], a[3],
-					  compat_ptr(a[4]));
+		ret = __compat_sys_recvmmsg(a0, compat_ptr(a1), a[2], a[3],
+					    compat_ptr(a[4]));
 		break;
 	case SYS_ACCEPT4:
 		ret = __sys_accept4(a0, compat_ptr(a1), compat_ptr(a[2]), a[3]);
-- 
2.16.2