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

From: Dominik Brodowski
Date: Fri Mar 16 2018 - 13:14:56 EST


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@xxxxxxxxxxxxx>
Cc: netdev@xxxxxxxxxxxxxxx
Signed-off-by: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx>
---
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