Commit 4257c8ca authored by Jens Axboe's avatar Jens Axboe
Browse files

net: separate out the msghdr copy from ___sys_{send,recv}msg() 



This is in preparation for enabling the io_uring helpers for sendmsg
and recvmsg to first copy the header for validation before continuing
with the operation.

There should be no functional changes in this patch.

Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 8042d6ce

net/socket.c

+95 −46
Original line number Diff line number Diff line
@@ -2264,15 +2264,10 @@ static int copy_msghdr_from_user(struct msghdr *kmsg, 
	return err < 0 ? err : 0;

}



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

			 struct msghdr *msg_sys, unsigned int flags,

			 struct used_address *used_address,

static int ____sys_sendmsg(struct socket *sock, struct msghdr *msg_sys,

			   unsigned int flags, struct used_address *used_address,

			   unsigned int allowed_msghdr_flags)

{

	struct compat_msghdr __user *msg_compat =

	    (struct compat_msghdr __user *)msg;

	struct sockaddr_storage address;

	struct iovec iovstack[UIO_FASTIOV], *iov = iovstack;

	unsigned char ctl[sizeof(struct cmsghdr) + 20]

				__aligned(sizeof(__kernel_size_t));

	/* 20 is size of ipv6_pktinfo */
@@ -2280,19 +2275,10 @@ static int ___sys_sendmsg(struct socket *sock, struct user_msghdr __user *msg, 
	int ctl_len;

	ssize_t err;



	msg_sys->msg_name = &address;



	if (MSG_CMSG_COMPAT & flags)

		err = get_compat_msghdr(msg_sys, msg_compat, NULL, &iov);

	else

		err = copy_msghdr_from_user(msg_sys, msg, NULL, &iov);

	if (err < 0)

		return err;



	err = -ENOBUFS;



	if (msg_sys->msg_controllen > INT_MAX)

		goto out_freeiov;

		goto out;

	flags |= (msg_sys->msg_flags & allowed_msghdr_flags);

	ctl_len = msg_sys->msg_controllen;

	if ((MSG_CMSG_COMPAT & flags) && ctl_len) {
@@ -2300,7 +2286,7 @@ static int ___sys_sendmsg(struct socket *sock, struct user_msghdr __user *msg, 
		    cmsghdr_from_user_compat_to_kern(msg_sys, sock->sk, ctl,

						     sizeof(ctl));

		if (err)

			goto out_freeiov;

			goto out;

		ctl_buf = msg_sys->msg_control;

		ctl_len = msg_sys->msg_controllen;

	} else if (ctl_len) {
@@ -2309,7 +2295,7 @@ static int ___sys_sendmsg(struct socket *sock, struct user_msghdr __user *msg, 
		if (ctl_len > sizeof(ctl)) {

			ctl_buf = sock_kmalloc(sock->sk, ctl_len, GFP_KERNEL);

			if (ctl_buf == NULL)

				goto out_freeiov;

				goto out;

		}

		err = -EFAULT;

		/*
@@ -2355,7 +2341,47 @@ static int ___sys_sendmsg(struct socket *sock, struct user_msghdr __user *msg, 
out_freectl:

	if (ctl_buf != ctl)

		sock_kfree_s(sock->sk, ctl_buf, ctl_len);

out_freeiov:

out:

	return err;

}



static int sendmsg_copy_msghdr(struct msghdr *msg,

			       struct user_msghdr __user *umsg, unsigned flags,

			       struct iovec **iov)

{

	int err;



	if (flags & MSG_CMSG_COMPAT) {

		struct compat_msghdr __user *msg_compat;



		msg_compat = (struct compat_msghdr __user *) umsg;

		err = get_compat_msghdr(msg, msg_compat, NULL, iov);

	} else {

		err = copy_msghdr_from_user(msg, umsg, NULL, iov);

	}

	if (err < 0)

		return err;



	return 0;

}



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

			 struct msghdr *msg_sys, unsigned int flags,

			 struct used_address *used_address,

			 unsigned int allowed_msghdr_flags)

{

	struct sockaddr_storage address;

	struct iovec iovstack[UIO_FASTIOV], *iov = iovstack;

	ssize_t err;



	msg_sys->msg_name = &address;



	err = sendmsg_copy_msghdr(msg_sys, msg, flags, &iov);

	if (err < 0)

		return err;



	err = ____sys_sendmsg(sock, msg_sys, flags, used_address,

				allowed_msghdr_flags);

	kfree(iov);

	return err;

}
@@ -2474,33 +2500,41 @@ SYSCALL_DEFINE4(sendmmsg, int, fd, struct mmsghdr __user *, mmsg, 
	return __sys_sendmmsg(fd, mmsg, vlen, flags, true);

}



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

			 struct msghdr *msg_sys, unsigned int flags, int nosec)

static int recvmsg_copy_msghdr(struct msghdr *msg,

			       struct user_msghdr __user *umsg, unsigned flags,

			       struct sockaddr __user **uaddr,

			       struct iovec **iov)

{

	ssize_t err;



	if (MSG_CMSG_COMPAT & flags) {

		struct compat_msghdr __user *msg_compat;



		msg_compat = (struct compat_msghdr __user *) umsg;

		err = get_compat_msghdr(msg, msg_compat, uaddr, iov);

	} else {

		err = copy_msghdr_from_user(msg, umsg, uaddr, iov);

	}

	if (err < 0)

		return err;



	return 0;

}



static int ____sys_recvmsg(struct socket *sock, struct msghdr *msg_sys,

			   struct user_msghdr __user *msg,

			   struct sockaddr __user *uaddr,

			   unsigned int flags, int nosec)

{

	struct compat_msghdr __user *msg_compat =

					(struct compat_msghdr __user *) msg;

	struct iovec iovstack[UIO_FASTIOV];

	struct iovec *iov = iovstack;

	int __user *uaddr_len = COMPAT_NAMELEN(msg);

	struct sockaddr_storage addr;

	unsigned long cmsg_ptr;

	int len;

	ssize_t err;



	/* kernel mode address */

	struct sockaddr_storage addr;



	/* user mode address pointers */

	struct sockaddr __user *uaddr;

	int __user *uaddr_len = COMPAT_NAMELEN(msg);



	msg_sys->msg_name = &addr;



	if (MSG_CMSG_COMPAT & flags)

		err = get_compat_msghdr(msg_sys, msg_compat, &uaddr, &iov);

	else

		err = copy_msghdr_from_user(msg_sys, msg, &uaddr, &iov);

	if (err < 0)

		return err;



	cmsg_ptr = (unsigned long)msg_sys->msg_control;

	msg_sys->msg_flags = flags & (MSG_CMSG_CLOEXEC|MSG_CMSG_COMPAT);
@@ -2511,7 +2545,7 @@ static int ___sys_recvmsg(struct socket *sock, struct user_msghdr __user *msg, 
		flags |= MSG_DONTWAIT;

	err = (nosec ? sock_recvmsg_nosec : sock_recvmsg)(sock, msg_sys, flags);

	if (err < 0)

		goto out_freeiov;

		goto out;

	len = err;



	if (uaddr != NULL) {
@@ -2519,12 +2553,12 @@ static int ___sys_recvmsg(struct socket *sock, struct user_msghdr __user *msg, 
					msg_sys->msg_namelen, uaddr,

					uaddr_len);

		if (err < 0)

			goto out_freeiov;

			goto out;

	}

	err = __put_user((msg_sys->msg_flags & ~MSG_CMSG_COMPAT),

			 COMPAT_FLAGS(msg));

	if (err)

		goto out_freeiov;

		goto out;

	if (MSG_CMSG_COMPAT & flags)

		err = __put_user((unsigned long)msg_sys->msg_control - cmsg_ptr,

				 &msg_compat->msg_controllen);
@@ -2532,10 +2566,25 @@ static int ___sys_recvmsg(struct socket *sock, struct user_msghdr __user *msg, 
		err = __put_user((unsigned long)msg_sys->msg_control - cmsg_ptr,

				 &msg->msg_controllen);

	if (err)

		goto out_freeiov;

		goto out;

	err = len;

out:

	return err;

}



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

			 struct msghdr *msg_sys, unsigned int flags, int nosec)

{

	struct iovec iovstack[UIO_FASTIOV], *iov = iovstack;

	/* user mode address pointers */

	struct sockaddr __user *uaddr;

	ssize_t err;



	err = recvmsg_copy_msghdr(msg_sys, msg, flags, &uaddr, &iov);

	if (err < 0)

		return err;



out_freeiov:

	err = ____sys_recvmsg(sock, msg_sys, msg, uaddr, flags, nosec);

	kfree(iov);

	return err;

}