net: socket: move check for forbid_cmsg_compat to __sys_...msg()

The non-compat codepaths for sys_...msg() verify that MSG_CMSG_COMPAT
is not set. By moving this check to the __sys_...msg() functions
(and making it dependent on a static flag passed to this function), we
can call the __sys...msg() functions instead of the syscall functions
in all cases. __sys_recvmmsg() does not need this trickery, as the
check is handled within the do_sys_recvmmsg() function internal to
net/socket.c.

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: Dominik Brodowski <linux@dominikbrodowski.net>
This commit is contained in:
Dominik Brodowski
2018-03-13 20:35:57 +01:00
parent 1255e26906
commit e1834a329d
3 changed files with 37 additions and 22 deletions

View File

@@ -346,13 +346,18 @@ extern int put_cmsg(struct msghdr*, int level, int type, int len, void *data);
struct timespec;
/* The __sys_...msg variants allow MSG_CMSG_COMPAT */
extern long __sys_recvmsg(int fd, struct user_msghdr __user *msg, unsigned flags);
extern long __sys_sendmsg(int fd, struct user_msghdr __user *msg, unsigned flags);
/* The __sys_...msg variants allow MSG_CMSG_COMPAT iff
* forbid_cmsg_compat==false
*/
extern long __sys_recvmsg(int fd, struct user_msghdr __user *msg,
unsigned int flags, bool forbid_cmsg_compat);
extern long __sys_sendmsg(int fd, struct user_msghdr __user *msg,
unsigned int flags, bool forbid_cmsg_compat);
extern int __sys_recvmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen,
unsigned int flags, struct timespec *timeout);
extern int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg,
unsigned int vlen, unsigned int flags);
unsigned int vlen, unsigned int flags,
bool forbid_cmsg_compat);
/* helpers which do the actual work for syscalls */
extern int __sys_recvfrom(int fd, void __user *ubuf, size_t size,