Commit 97cf0ef9 authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'improve-msg_control-kernel-vs-user-pointer-handling' 



Christoph Hellwig says:

====================
improve msg_control kernel vs user pointer handling

this series replace the msg_control in the kernel msghdr structure
with an anonymous union and separate fields for kernel vs user
pointers.  In addition to helping a bit with type safety and reducing
sparse warnings, this also allows to remove the set_fs() in
kernel_recvmsg, helping with an eventual entire removal of set_fs().
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 3242956b 1f466e1f

include/linux/socket.h

+15 −2
Original line number Diff line number Diff line
@@ -50,7 +50,17 @@ struct msghdr { 
	void		*msg_name;	/* ptr to socket address structure */

	int		msg_namelen;	/* size of socket address structure */

	struct iov_iter	msg_iter;	/* data */

	void		*msg_control;	/* ancillary data */



	/*

	 * Ancillary data. msg_control_user is the user buffer used for the

	 * recv* side when msg_control_is_user is set, msg_control is the kernel

	 * buffer used for all other cases.

	 */

	union {

		void		*msg_control;

		void __user	*msg_control_user;

	};

	bool		msg_control_is_user : 1;

	__kernel_size_t	msg_controllen;	/* ancillary data buffer length */

	unsigned int	msg_flags;	/* flags on received message */

	struct kiocb	*msg_iocb;	/* ptr to iocb for async requests */
@@ -94,7 +104,10 @@ struct cmsghdr { 


#define CMSG_ALIGN(len) ( ((len)+sizeof(long)-1) & ~(sizeof(long)-1) )



#define CMSG_DATA(cmsg)	((void *)((char *)(cmsg) + sizeof(struct cmsghdr)))

#define CMSG_DATA(cmsg) \

	((void *)(cmsg) + sizeof(struct cmsghdr))

#define CMSG_USER_DATA(cmsg) \

	((void __user *)(cmsg) + sizeof(struct cmsghdr))

#define CMSG_SPACE(len) (sizeof(struct cmsghdr) + CMSG_ALIGN(len))

#define CMSG_LEN(len) (sizeof(struct cmsghdr) + (len))

net/compat.c

+3 −2
Original line number Diff line number Diff line
@@ -56,7 +56,8 @@ int __get_compat_msghdr(struct msghdr *kmsg, 
	if (kmsg->msg_namelen > sizeof(struct sockaddr_storage))

		kmsg->msg_namelen = sizeof(struct sockaddr_storage);



	kmsg->msg_control = compat_ptr(msg.msg_control);

	kmsg->msg_control_is_user = true;

	kmsg->msg_control_user = compat_ptr(msg.msg_control);

	kmsg->msg_controllen = msg.msg_controllen;



	if (save_addr)
@@ -121,7 +122,7 @@ int get_compat_msghdr(struct msghdr *kmsg, 
	((ucmlen) >= sizeof(struct compat_cmsghdr) && \

	 (ucmlen) <= (unsigned long) \

	 ((mhdr)->msg_controllen - \

	  ((char *)(ucmsg) - (char *)(mhdr)->msg_control)))

	  ((char __user *)(ucmsg) - (char __user *)(mhdr)->msg_control_user)))



static inline struct compat_cmsghdr __user *cmsg_compat_nxthdr(struct msghdr *msg,

		struct compat_cmsghdr __user *cmsg, int cmsg_len)

net/core/scm.c

+78 −63
Original line number Diff line number Diff line
@@ -212,16 +212,12 @@ EXPORT_SYMBOL(__scm_send); 


int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)

{

	struct cmsghdr __user *cm

		= (__force struct cmsghdr __user *)msg->msg_control;

	struct cmsghdr cmhdr;

	int cmlen = CMSG_LEN(len);

	int err;



	if (MSG_CMSG_COMPAT & msg->msg_flags)

	if (msg->msg_flags & MSG_CMSG_COMPAT)

		return put_cmsg_compat(msg, level, type, len, data);



	if (cm==NULL || msg->msg_controllen < sizeof(*cm)) {

	if (!msg->msg_control || msg->msg_controllen < sizeof(struct cmsghdr)) {

		msg->msg_flags |= MSG_CTRUNC;

		return 0; /* XXX: return error? check spec. */

	}
@@ -229,23 +225,30 @@ int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data) 
		msg->msg_flags |= MSG_CTRUNC;

		cmlen = msg->msg_controllen;

	}



	if (msg->msg_control_is_user) {

		struct cmsghdr __user *cm = msg->msg_control_user;

		struct cmsghdr cmhdr;



		cmhdr.cmsg_level = level;

		cmhdr.cmsg_type = type;

		cmhdr.cmsg_len = cmlen;

		if (copy_to_user(cm, &cmhdr, sizeof cmhdr) ||

		    copy_to_user(CMSG_USER_DATA(cm), data, cmlen - sizeof(*cm)))

			return -EFAULT;

	} else {

		struct cmsghdr *cm = msg->msg_control;



		cm->cmsg_level = level;

		cm->cmsg_type = type;

		cm->cmsg_len = cmlen;

		memcpy(CMSG_DATA(cm), data, cmlen - sizeof(*cm));

	}



	err = -EFAULT;

	if (copy_to_user(cm, &cmhdr, sizeof cmhdr))

		goto out;

	if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr)))

		goto out;

	cmlen = CMSG_SPACE(len);

	if (msg->msg_controllen < cmlen)

		cmlen = msg->msg_controllen;

	cmlen = min(CMSG_SPACE(len), msg->msg_controllen);

	msg->msg_control += cmlen;

	msg->msg_controllen -= cmlen;

	err = 0;

out:

	return err;

	return 0;

}

EXPORT_SYMBOL(put_cmsg);
@@ -277,59 +280,70 @@ void put_cmsg_scm_timestamping(struct msghdr *msg, struct scm_timestamping_inter 
}

EXPORT_SYMBOL(put_cmsg_scm_timestamping);



static int __scm_install_fd(struct file *file, int __user *ufd, int o_flags)

{

	struct socket *sock;

	int new_fd;

	int error;



	error = security_file_receive(file);

	if (error)

		return error;



	new_fd = get_unused_fd_flags(o_flags);

	if (new_fd < 0)

		return new_fd;



	error = put_user(new_fd, ufd);

	if (error) {

		put_unused_fd(new_fd);

		return error;

	}



	/* Bump the usage count and install the file. */

	sock = sock_from_file(file, &error);

	if (sock) {

		sock_update_netprioidx(&sock->sk->sk_cgrp_data);

		sock_update_classid(&sock->sk->sk_cgrp_data);

	}

	fd_install(new_fd, get_file(file));

	return error;

}



static int scm_max_fds(struct msghdr *msg)

{

	if (msg->msg_controllen <= sizeof(struct cmsghdr))

		return 0;

	return (msg->msg_controllen - sizeof(struct cmsghdr)) / sizeof(int);

}



void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)

{

	struct cmsghdr __user *cm

		= (__force struct cmsghdr __user*)msg->msg_control;



	int fdmax = 0;

	int fdnum = scm->fp->count;

	struct file **fp = scm->fp->fp;

	int __user *cmfptr;

	int o_flags = (msg->msg_flags & MSG_CMSG_CLOEXEC) ? O_CLOEXEC : 0;

	int fdmax = min_t(int, scm_max_fds(msg), scm->fp->count);

	int __user *cmsg_data = CMSG_USER_DATA(cm);

	int err = 0, i;



	if (MSG_CMSG_COMPAT & msg->msg_flags) {

	if (msg->msg_flags & MSG_CMSG_COMPAT) {

		scm_detach_fds_compat(msg, scm);

		return;

	}



	if (msg->msg_controllen > sizeof(struct cmsghdr))

		fdmax = ((msg->msg_controllen - sizeof(struct cmsghdr))

			 / sizeof(int));



	if (fdnum < fdmax)

		fdmax = fdnum;

	/* no use for FD passing from kernel space callers */

	if (WARN_ON_ONCE(!msg->msg_control_is_user))

		return;



	for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax;

	     i++, cmfptr++)

	{

		struct socket *sock;

		int new_fd;

		err = security_file_receive(fp[i]);

	for (i = 0; i < fdmax; i++) {

		err = __scm_install_fd(scm->fp->fp[i], cmsg_data + i, o_flags);

		if (err)

			break;

		err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & msg->msg_flags

					  ? O_CLOEXEC : 0);

		if (err < 0)

			break;

		new_fd = err;

		err = put_user(new_fd, cmfptr);

		if (err) {

			put_unused_fd(new_fd);

			break;

		}

		/* Bump the usage count and install the file. */

		sock = sock_from_file(fp[i], &err);

		if (sock) {

			sock_update_netprioidx(&sock->sk->sk_cgrp_data);

			sock_update_classid(&sock->sk->sk_cgrp_data);

		}

		fd_install(new_fd, get_file(fp[i]));

	}



	if (i > 0)

	{

	if (i > 0)  {

		int cmlen = CMSG_LEN(i * sizeof(int));



		err = put_user(SOL_SOCKET, &cm->cmsg_level);

		if (!err)

			err = put_user(SCM_RIGHTS, &cm->cmsg_type);
@@ -343,12 +357,13 @@ void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm) 
			msg->msg_controllen -= cmlen;

		}

	}

	if (i < fdnum || (fdnum && fdmax <= 0))



	if (i < scm->fp->count || (scm->fp->count && fdmax <= 0))

		msg->msg_flags |= MSG_CTRUNC;



	/*

	 * All of the files that fit in the message have had their

	 * usage counts incremented, so we just free the list.

	 * All of the files that fit in the message have had their usage counts

	 * incremented, so we just free the list.

	 */

	__scm_destroy(scm);

}

net/ipv4/ip_sockglue.c

+2 −1
Original line number Diff line number Diff line
@@ -1492,7 +1492,8 @@ static int do_ip_getsockopt(struct sock *sk, int level, int optname, 
		if (sk->sk_type != SOCK_STREAM)

			return -ENOPROTOOPT;



		msg.msg_control = (__force void *) optval;

		msg.msg_control_is_user = true;

		msg.msg_control_user = optval;

		msg.msg_controllen = len;

		msg.msg_flags = flags;

net/socket.c

+6 −16
Original line number Diff line number Diff line
@@ -924,14 +924,9 @@ EXPORT_SYMBOL(sock_recvmsg); 
int kernel_recvmsg(struct socket *sock, struct msghdr *msg,

		   struct kvec *vec, size_t num, size_t size, int flags)

{

	mm_segment_t oldfs = get_fs();

	int result;



	msg->msg_control_is_user = false;

	iov_iter_kvec(&msg->msg_iter, READ, vec, num, size);

	set_fs(KERNEL_DS);

	result = sock_recvmsg(sock, msg, flags);

	set_fs(oldfs);

	return result;

	return sock_recvmsg(sock, msg, flags);

}

EXPORT_SYMBOL(kernel_recvmsg);
@@ -2239,7 +2234,8 @@ int __copy_msghdr_from_user(struct msghdr *kmsg, 
	if (copy_from_user(&msg, umsg, sizeof(*umsg)))

		return -EFAULT;



	kmsg->msg_control = (void __force *)msg.msg_control;

	kmsg->msg_control_is_user = true;

	kmsg->msg_control_user = msg.msg_control;

	kmsg->msg_controllen = msg.msg_controllen;

	kmsg->msg_flags = msg.msg_flags;
@@ -2331,16 +2327,10 @@ static int ____sys_sendmsg(struct socket *sock, struct msghdr *msg_sys, 
				goto out;

		}

		err = -EFAULT;

		/*

		 * Careful! Before this, msg_sys->msg_control contains a user pointer.

		 * Afterwards, it will be a kernel pointer. Thus the compiler-assisted

		 * checking falls down on this.

		 */

		if (copy_from_user(ctl_buf,

				   (void __user __force *)msg_sys->msg_control,

				   ctl_len))

		if (copy_from_user(ctl_buf, msg_sys->msg_control_user, ctl_len))

			goto out_freectl;

		msg_sys->msg_control = ctl_buf;

		msg_sys->msg_control_is_user = false;

	}

	msg_sys->msg_flags = flags;

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