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Commit e1834a32 authored by Dominik Brodowski's avatar Dominik Brodowski
Browse files

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: default avatarDominik Brodowski <linux@dominikbrodowski.net>
parent 1255e269

include/linux/socket.h

+9 −4
Original line number Original line Diff line number Diff line
@@ -346,13 +346,18 @@ extern int put_cmsg(struct msghdr*, int level, int type, int len, void *data); 




struct timespec;

struct timespec;





/* The __sys_...msg variants allow MSG_CMSG_COMPAT */

/* The __sys_...msg variants allow MSG_CMSG_COMPAT iff

extern long __sys_recvmsg(int fd, struct user_msghdr __user *msg, unsigned flags);

 * forbid_cmsg_compat==false

extern long __sys_sendmsg(int fd, struct user_msghdr __user *msg, unsigned flags);

 */

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,

extern int __sys_recvmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen,

			  unsigned int flags, struct timespec *timeout);

			  unsigned int flags, struct timespec *timeout);

extern int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg,

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 */

/* helpers which do the actual work for syscalls */

extern int __sys_recvfrom(int fd, void __user *ubuf, size_t size,

extern int __sys_recvfrom(int fd, void __user *ubuf, size_t size,

net/compat.c

+5 −3
Original line number Original line Diff line number Diff line
@@ -736,19 +736,21 @@ static unsigned char nas[21] = { 




COMPAT_SYSCALL_DEFINE3(sendmsg, int, fd, struct compat_msghdr __user *, msg, unsigned int, flags)

COMPAT_SYSCALL_DEFINE3(sendmsg, int, fd, struct compat_msghdr __user *, msg, unsigned int, flags)

{

{

	return __sys_sendmsg(fd, (struct user_msghdr __user *)msg, flags | MSG_CMSG_COMPAT);

	return __sys_sendmsg(fd, (struct user_msghdr __user *)msg,

			     flags | MSG_CMSG_COMPAT, false);

}

}





COMPAT_SYSCALL_DEFINE4(sendmmsg, int, fd, struct compat_mmsghdr __user *, mmsg,

COMPAT_SYSCALL_DEFINE4(sendmmsg, int, fd, struct compat_mmsghdr __user *, mmsg,

		       unsigned int, vlen, unsigned int, flags)

		       unsigned int, vlen, unsigned int, flags)

{

{

	return __sys_sendmmsg(fd, (struct mmsghdr __user *)mmsg, vlen,

	return __sys_sendmmsg(fd, (struct mmsghdr __user *)mmsg, vlen,

			      flags | MSG_CMSG_COMPAT);

			      flags | MSG_CMSG_COMPAT, false);

}

}





COMPAT_SYSCALL_DEFINE3(recvmsg, int, fd, struct compat_msghdr __user *, msg, unsigned int, flags)

COMPAT_SYSCALL_DEFINE3(recvmsg, int, fd, struct compat_msghdr __user *, msg, unsigned int, flags)

{

{

	return __sys_recvmsg(fd, (struct user_msghdr __user *)msg, flags | MSG_CMSG_COMPAT);

	return __sys_recvmsg(fd, (struct user_msghdr __user *)msg,

			     flags | MSG_CMSG_COMPAT, false);

}

}





COMPAT_SYSCALL_DEFINE4(recv, int, fd, void __user *, buf, compat_size_t, len, unsigned int, flags)

COMPAT_SYSCALL_DEFINE4(recv, int, fd, void __user *, buf, compat_size_t, len, unsigned int, flags)

net/socket.c

+23 −15
Original line number Original line Diff line number Diff line
@@ -2137,12 +2137,16 @@ static int ___sys_sendmsg(struct socket *sock, struct user_msghdr __user *msg, 
 *	BSD sendmsg interface

 *	BSD sendmsg interface

 */

 */





long __sys_sendmsg(int fd, struct user_msghdr __user *msg, unsigned flags)

long __sys_sendmsg(int fd, struct user_msghdr __user *msg, unsigned int flags,

		   bool forbid_cmsg_compat)

{

{

	int fput_needed, err;

	int fput_needed, err;

	struct msghdr msg_sys;

	struct msghdr msg_sys;

	struct socket *sock;

	struct socket *sock;





	if (forbid_cmsg_compat && (flags & MSG_CMSG_COMPAT))

		return -EINVAL;



	sock = sockfd_lookup_light(fd, &err, &fput_needed);

	sock = sockfd_lookup_light(fd, &err, &fput_needed);

	if (!sock)

	if (!sock)

		goto out;

		goto out;
@@ -2156,9 +2160,7 @@ long __sys_sendmsg(int fd, struct user_msghdr __user *msg, unsigned flags) 




SYSCALL_DEFINE3(sendmsg, int, fd, struct user_msghdr __user *, msg, unsigned int, flags)

SYSCALL_DEFINE3(sendmsg, int, fd, struct user_msghdr __user *, msg, unsigned int, flags)

{

{

	if (flags & MSG_CMSG_COMPAT)

	return __sys_sendmsg(fd, msg, flags, true);

		return -EINVAL;

	return __sys_sendmsg(fd, msg, flags);

}

}





/*

/*
@@ -2166,7 +2168,7 @@ SYSCALL_DEFINE3(sendmsg, int, fd, struct user_msghdr __user *, msg, unsigned int 
 */

 */





int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen,

int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen,

		   unsigned int flags)

		   unsigned int flags, bool forbid_cmsg_compat)

{

{

	int fput_needed, err, datagrams;

	int fput_needed, err, datagrams;

	struct socket *sock;

	struct socket *sock;
@@ -2176,6 +2178,9 @@ int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen, 
	struct used_address used_address;

	struct used_address used_address;

	unsigned int oflags = flags;

	unsigned int oflags = flags;





	if (forbid_cmsg_compat && (flags & MSG_CMSG_COMPAT))

		return -EINVAL;



	if (vlen > UIO_MAXIOV)

	if (vlen > UIO_MAXIOV)

		vlen = UIO_MAXIOV;

		vlen = UIO_MAXIOV;
@@ -2232,9 +2237,7 @@ int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen, 
SYSCALL_DEFINE4(sendmmsg, int, fd, struct mmsghdr __user *, mmsg,

SYSCALL_DEFINE4(sendmmsg, int, fd, struct mmsghdr __user *, mmsg,

		unsigned int, vlen, unsigned int, flags)

		unsigned int, vlen, unsigned int, flags)

{

{

	if (flags & MSG_CMSG_COMPAT)

	return __sys_sendmmsg(fd, mmsg, vlen, flags, true);

		return -EINVAL;

	return __sys_sendmmsg(fd, mmsg, vlen, flags);

}

}





static int ___sys_recvmsg(struct socket *sock, struct user_msghdr __user *msg,

static int ___sys_recvmsg(struct socket *sock, struct user_msghdr __user *msg,
@@ -2307,12 +2310,16 @@ static int ___sys_recvmsg(struct socket *sock, struct user_msghdr __user *msg, 
 *	BSD recvmsg interface

 *	BSD recvmsg interface

 */

 */





long __sys_recvmsg(int fd, struct user_msghdr __user *msg, unsigned flags)

long __sys_recvmsg(int fd, struct user_msghdr __user *msg, unsigned int flags,

		   bool forbid_cmsg_compat)

{

{

	int fput_needed, err;

	int fput_needed, err;

	struct msghdr msg_sys;

	struct msghdr msg_sys;

	struct socket *sock;

	struct socket *sock;





	if (forbid_cmsg_compat && (flags & MSG_CMSG_COMPAT))

		return -EINVAL;



	sock = sockfd_lookup_light(fd, &err, &fput_needed);

	sock = sockfd_lookup_light(fd, &err, &fput_needed);

	if (!sock)

	if (!sock)

		goto out;

		goto out;
@@ -2327,9 +2334,7 @@ long __sys_recvmsg(int fd, struct user_msghdr __user *msg, unsigned flags) 
SYSCALL_DEFINE3(recvmsg, int, fd, struct user_msghdr __user *, msg,

SYSCALL_DEFINE3(recvmsg, int, fd, struct user_msghdr __user *, msg,

		unsigned int, flags)

		unsigned int, flags)

{

{

	if (flags & MSG_CMSG_COMPAT)

	return __sys_recvmsg(fd, msg, flags, true);

		return -EINVAL;

	return __sys_recvmsg(fd, msg, flags);

}

}





/*

/*
@@ -2580,13 +2585,16 @@ SYSCALL_DEFINE2(socketcall, int, call, unsigned long __user *, args) 
				     (int __user *)a[4]);

				     (int __user *)a[4]);

		break;

		break;

	case SYS_SENDMSG:

	case SYS_SENDMSG:

		err = sys_sendmsg(a0, (struct user_msghdr __user *)a1, a[2]);

		err = __sys_sendmsg(a0, (struct user_msghdr __user *)a1,

				    a[2], true);

		break;

		break;

	case SYS_SENDMMSG:

	case SYS_SENDMMSG:

		err = sys_sendmmsg(a0, (struct mmsghdr __user *)a1, a[2], a[3]);

		err = __sys_sendmmsg(a0, (struct mmsghdr __user *)a1, a[2],

				     a[3], true);

		break;

		break;

	case SYS_RECVMSG:

	case SYS_RECVMSG:

		err = sys_recvmsg(a0, (struct user_msghdr __user *)a1, a[2]);

		err = __sys_recvmsg(a0, (struct user_msghdr __user *)a1,

				    a[2], true);

		break;

		break;

	case SYS_RECVMMSG:

	case SYS_RECVMMSG:

		err = do_sys_recvmmsg(a0, (struct mmsghdr __user *)a1, a[2],

		err = do_sys_recvmmsg(a0, (struct mmsghdr __user *)a1, a[2],