[net-next-2.6.git] / net / core / scm.c

/* scm.c - Socket level control messages processing.
 *
 * Author:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
 *              Alignment and value checking mods by Craig Metz
 *
 *		This program is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/signal.h>
#include <linux/capability.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/kernel.h>
#include <linux/stat.h>
#include <linux/socket.h>
#include <linux/file.h>
#include <linux/fcntl.h>
#include <linux/net.h>
#include <linux/interrupt.h>
#include <linux/netdevice.h>
#include <linux/security.h>
#include <linux/pid.h>
#include <linux/nsproxy.h>

#include <asm/system.h>
#include <asm/uaccess.h>

#include <net/protocol.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/compat.h>
#include <net/scm.h>


/*
 *	Only allow a user to send credentials, that they could set with
 *	setu(g)id.
 */

static __inline__ int scm_check_creds(struct ucred *creds)
{
	const struct cred *cred = current_cred();

	if ((creds->pid == task_tgid_vnr(current) || capable(CAP_SYS_ADMIN)) &&
	    ((creds->uid == cred->uid   || creds->uid == cred->euid ||
	      creds->uid == cred->suid) || capable(CAP_SETUID)) &&
	    ((creds->gid == cred->gid   || creds->gid == cred->egid ||
	      creds->gid == cred->sgid) || capable(CAP_SETGID))) {
	       return 0;
	}
	return -EPERM;
}

static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp)
{
	int *fdp = (int*)CMSG_DATA(cmsg);
	struct scm_fp_list *fpl = *fplp;
	struct file **fpp;
	int i, num;

	num = (cmsg->cmsg_len - CMSG_ALIGN(sizeof(struct cmsghdr)))/sizeof(int);

	if (num <= 0)
		return 0;

	if (num > SCM_MAX_FD)
		return -EINVAL;

	if (!fpl)
	{
		fpl = kmalloc(sizeof(struct scm_fp_list), GFP_KERNEL);
		if (!fpl)
			return -ENOMEM;
		*fplp = fpl;
		INIT_LIST_HEAD(&fpl->list);
		fpl->count = 0;
	}
	fpp = &fpl->fp[fpl->count];

	if (fpl->count + num > SCM_MAX_FD)
		return -EINVAL;

	/*
	 *	Verify the descriptors and increment the usage count.
	 */

	for (i=0; i< num; i++)
	{
		int fd = fdp[i];
		struct file *file;

		if (fd < 0 || !(file = fget(fd)))
			return -EBADF;
		*fpp++ = file;
		fpl->count++;
	}
	return num;
}

void __scm_destroy(struct scm_cookie *scm)
{
	struct scm_fp_list *fpl = scm->fp;
	int i;

	if (fpl) {
		scm->fp = NULL;
		if (current->scm_work_list) {
			list_add_tail(&fpl->list, current->scm_work_list);
		} else {
			LIST_HEAD(work_list);

			current->scm_work_list = &work_list;

			list_add(&fpl->list, &work_list);
			while (!list_empty(&work_list)) {
				fpl = list_first_entry(&work_list, struct scm_fp_list, list);

				list_del(&fpl->list);
				for (i=fpl->count-1; i>=0; i--)
					fput(fpl->fp[i]);
				kfree(fpl);
			}

			current->scm_work_list = NULL;
		}
	}
}

int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
{
	struct cmsghdr *cmsg;
	int err;

	for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg))
	{
		err = -EINVAL;

		/* Verify that cmsg_len is at least sizeof(struct cmsghdr) */
		/* The first check was omitted in <= 2.2.5. The reasoning was
		   that parser checks cmsg_len in any case, so that
		   additional check would be work duplication.
		   But if cmsg_level is not SOL_SOCKET, we do not check
		   for too short ancillary data object at all! Oops.
		   OK, let's add it...
		 */
		if (!CMSG_OK(msg, cmsg))
			goto error;

		if (cmsg->cmsg_level != SOL_SOCKET)
			continue;

		switch (cmsg->cmsg_type)
		{
		case SCM_RIGHTS:
			err=scm_fp_copy(cmsg, &p->fp);
			if (err<0)
				goto error;
			break;
		case SCM_CREDENTIALS:
			if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
				goto error;
			memcpy(&p->creds, CMSG_DATA(cmsg), sizeof(struct ucred));
			err = scm_check_creds(&p->creds);
			if (err)
				goto error;
			break;
		default:
			goto error;
		}
	}

	if (p->fp && !p->fp->count)
	{
		kfree(p->fp);
		p->fp = NULL;
	}
	return 0;

error:
	scm_destroy(p);
	return err;
}

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

	if (cm==NULL || msg->msg_controllen < sizeof(*cm)) {
		msg->msg_flags |= MSG_CTRUNC;
		return 0; /* XXX: return error? check spec. */
	}
	if (msg->msg_controllen < cmlen) {
		msg->msg_flags |= MSG_CTRUNC;
		cmlen = msg->msg_controllen;
	}
	cmhdr.cmsg_level = level;
	cmhdr.cmsg_type = type;
	cmhdr.cmsg_len = cmlen;

	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;
	msg->msg_control += cmlen;
	msg->msg_controllen -= cmlen;
	err = 0;
out:
	return err;
}

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 err = 0, i;

	if (MSG_CMSG_COMPAT & msg->msg_flags) {
		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;

	for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax;
	     i++, cmfptr++)
	{
		int new_fd;
		err = security_file_receive(fp[i]);
		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. */
		get_file(fp[i]);
		fd_install(new_fd, fp[i]);
	}

	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);
		if (!err)
			err = put_user(cmlen, &cm->cmsg_len);
		if (!err) {
			cmlen = CMSG_SPACE(i*sizeof(int));
			msg->msg_control += cmlen;
			msg->msg_controllen -= cmlen;
		}
	}
	if (i < fdnum || (fdnum && 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.
	 */
	__scm_destroy(scm);
}

struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
{
	struct scm_fp_list *new_fpl;
	int i;

	if (!fpl)
		return NULL;

	new_fpl = kmalloc(sizeof(*fpl), GFP_KERNEL);
	if (new_fpl) {
		INIT_LIST_HEAD(&new_fpl->list);
		for (i=fpl->count-1; i>=0; i--)
			get_file(fpl->fp[i]);
		memcpy(new_fpl, fpl, sizeof(*fpl));
	}
	return new_fpl;
}

EXPORT_SYMBOL(__scm_destroy);
EXPORT_SYMBOL(__scm_send);
EXPORT_SYMBOL(put_cmsg);
EXPORT_SYMBOL(scm_detach_fds);
EXPORT_SYMBOL(scm_fp_dup);
Commit	Line	Data
1da177e4 LT	1	/* scm.c - Socket level control messages processing.
	2	*
	3	* Author: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
	4	* Alignment and value checking mods by Craig Metz
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public License
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the License, or (at your option) any later version.
	10	*/
	11
	12	#include <linux/module.h>
	13	#include <linux/signal.h>
4fc268d2	14	#include <linux/capability.h>
1da177e4 LT	15	#include <linux/errno.h>
	16	#include <linux/sched.h>
	17	#include <linux/mm.h>
	18	#include <linux/kernel.h>
1da177e4 LT	19	#include <linux/stat.h>
	20	#include <linux/socket.h>
	21	#include <linux/file.h>
	22	#include <linux/fcntl.h>
	23	#include <linux/net.h>
	24	#include <linux/interrupt.h>
	25	#include <linux/netdevice.h>
	26	#include <linux/security.h>
b488893a PE	27	#include <linux/pid.h>
b488893a PE	28	#include <linux/nsproxy.h>
1da177e4 LT	29
	30	#include <asm/system.h>
	31	#include <asm/uaccess.h>
	32
	33	#include <net/protocol.h>
	34	#include <linux/skbuff.h>
	35	#include <net/sock.h>
	36	#include <net/compat.h>
	37	#include <net/scm.h>
	38
	39
	40	/*
4ec93edb	41	* Only allow a user to send credentials, that they could set with
1da177e4 LT	42	* setu(g)id.
	43	*/
	44
	45	static __inline__ int scm_check_creds(struct ucred *creds)
	46	{
86a264ab	47	const struct cred *cred = current_cred();
b6dff3ec	48
b488893a	49	if ((creds->pid == task_tgid_vnr(current) \|\| capable(CAP_SYS_ADMIN)) &&
b6dff3ec DH	50	((creds->uid == cred->uid \|\| creds->uid == cred->euid \|\|
	51	creds->uid == cred->suid) \|\| capable(CAP_SETUID)) &&
	52	((creds->gid == cred->gid \|\| creds->gid == cred->egid \|\|
	53	creds->gid == cred->sgid) \|\| capable(CAP_SETGID))) {
1da177e4 LT	54	return 0;
	55	}
	56	return -EPERM;
	57	}
	58
	59	static int scm_fp_copy(struct cmsghdr cmsg, struct scm_fp_list *fplp)
	60	{
	61	int fdp = (int)CMSG_DATA(cmsg);
	62	struct scm_fp_list fpl = fplp;
	63	struct file **fpp;
	64	int i, num;
	65
	66	num = (cmsg->cmsg_len - CMSG_ALIGN(sizeof(struct cmsghdr)))/sizeof(int);
	67
	68	if (num <= 0)
	69	return 0;
	70
	71	if (num > SCM_MAX_FD)
	72	return -EINVAL;
	73
	74	if (!fpl)
	75	{
	76	fpl = kmalloc(sizeof(struct scm_fp_list), GFP_KERNEL);
	77	if (!fpl)
	78	return -ENOMEM;
	79	*fplp = fpl;
f8d570a4	80	INIT_LIST_HEAD(&fpl->list);
1da177e4 LT	81	fpl->count = 0;
	82	}
	83	fpp = &fpl->fp[fpl->count];
	84
	85	if (fpl->count + num > SCM_MAX_FD)
	86	return -EINVAL;
4ec93edb	87
1da177e4 LT	88	/*
	89	* Verify the descriptors and increment the usage count.
	90	*/
4ec93edb	91
1da177e4 LT	92	for (i=0; i< num; i++)
	93	{
	94	int fd = fdp[i];
	95	struct file *file;
	96
	97	if (fd < 0 \|\| !(file = fget(fd)))
	98	return -EBADF;
	99	*fpp++ = file;
	100	fpl->count++;
	101	}
	102	return num;
	103	}
	104
	105	void __scm_destroy(struct scm_cookie *scm)
	106	{
	107	struct scm_fp_list *fpl = scm->fp;
	108	int i;
	109
	110	if (fpl) {
	111	scm->fp = NULL;
f8d570a4 DM	112	if (current->scm_work_list) {
	113	list_add_tail(&fpl->list, current->scm_work_list);
	114	} else {
	115	LIST_HEAD(work_list);
	116
	117	current->scm_work_list = &work_list;
	118
	119	list_add(&fpl->list, &work_list);
	120	while (!list_empty(&work_list)) {
	121	fpl = list_first_entry(&work_list, struct scm_fp_list, list);
	122
	123	list_del(&fpl->list);
	124	for (i=fpl->count-1; i>=0; i--)
	125	fput(fpl->fp[i]);
	126	kfree(fpl);
	127	}
	128
	129	current->scm_work_list = NULL;
	130	}
1da177e4 LT	131	}
	132	}
	133
	134	int __scm_send(struct socket sock, struct msghdr msg, struct scm_cookie *p)
	135	{
	136	struct cmsghdr *cmsg;
	137	int err;
	138
	139	for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg))
	140	{
	141	err = -EINVAL;
	142
	143	/* Verify that cmsg_len is at least sizeof(struct cmsghdr) */
	144	/* The first check was omitted in <= 2.2.5. The reasoning was
	145	that parser checks cmsg_len in any case, so that
	146	additional check would be work duplication.
4ec93edb	147	But if cmsg_level is not SOL_SOCKET, we do not check
1da177e4 LT	148	for too short ancillary data object at all! Oops.
	149	OK, let's add it...
	150	*/
	151	if (!CMSG_OK(msg, cmsg))
	152	goto error;
	153
	154	if (cmsg->cmsg_level != SOL_SOCKET)
	155	continue;
	156
	157	switch (cmsg->cmsg_type)
	158	{
	159	case SCM_RIGHTS:
	160	err=scm_fp_copy(cmsg, &p->fp);
	161	if (err<0)
	162	goto error;
	163	break;
	164	case SCM_CREDENTIALS:
	165	if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
	166	goto error;
	167	memcpy(&p->creds, CMSG_DATA(cmsg), sizeof(struct ucred));
	168	err = scm_check_creds(&p->creds);
	169	if (err)
	170	goto error;
	171	break;
	172	default:
	173	goto error;
	174	}
	175	}
	176
	177	if (p->fp && !p->fp->count)
	178	{
	179	kfree(p->fp);
	180	p->fp = NULL;
	181	}
	182	return 0;
4ec93edb	183
1da177e4 LT	184	error:
	185	scm_destroy(p);
	186	return err;
	187	}
	188
	189	int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
	190	{
cfcabdcc SH	191	struct cmsghdr __user *cm
cfcabdcc SH	192	= (__force struct cmsghdr __user *)msg->msg_control;
1da177e4 LT	193	struct cmsghdr cmhdr;
	194	int cmlen = CMSG_LEN(len);
	195	int err;
	196
	197	if (MSG_CMSG_COMPAT & msg->msg_flags)
	198	return put_cmsg_compat(msg, level, type, len, data);
	199
	200	if (cm==NULL \|\| msg->msg_controllen < sizeof(*cm)) {
	201	msg->msg_flags \|= MSG_CTRUNC;
	202	return 0; /* XXX: return error? check spec. */
	203	}
	204	if (msg->msg_controllen < cmlen) {
	205	msg->msg_flags \|= MSG_CTRUNC;
	206	cmlen = msg->msg_controllen;
	207	}
	208	cmhdr.cmsg_level = level;
	209	cmhdr.cmsg_type = type;
	210	cmhdr.cmsg_len = cmlen;
	211
	212	err = -EFAULT;
	213	if (copy_to_user(cm, &cmhdr, sizeof cmhdr))
4ec93edb	214	goto out;
1da177e4 LT	215	if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr)))
	216	goto out;
	217	cmlen = CMSG_SPACE(len);
1ac70e7a WY	218	if (msg->msg_controllen < cmlen)
1ac70e7a WY	219	cmlen = msg->msg_controllen;
1da177e4 LT	220	msg->msg_control += cmlen;
	221	msg->msg_controllen -= cmlen;
	222	err = 0;
	223	out:
	224	return err;
	225	}
	226
	227	void scm_detach_fds(struct msghdr msg, struct scm_cookie scm)
	228	{
cfcabdcc SH	229	struct cmsghdr __user *cm
cfcabdcc SH	230	= (__force struct cmsghdr __user*)msg->msg_control;
1da177e4 LT	231
	232	int fdmax = 0;
	233	int fdnum = scm->fp->count;
	234	struct file **fp = scm->fp->fp;
	235	int __user *cmfptr;
	236	int err = 0, i;
	237
	238	if (MSG_CMSG_COMPAT & msg->msg_flags) {
	239	scm_detach_fds_compat(msg, scm);
	240	return;
	241	}
	242
	243	if (msg->msg_controllen > sizeof(struct cmsghdr))
	244	fdmax = ((msg->msg_controllen - sizeof(struct cmsghdr))
	245	/ sizeof(int));
	246
	247	if (fdnum < fdmax)
	248	fdmax = fdnum;
	249
cfcabdcc SH	250	for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax;
cfcabdcc SH	251	i++, cmfptr++)
1da177e4 LT	252	{
	253	int new_fd;
	254	err = security_file_receive(fp[i]);
	255	if (err)
	256	break;
4a19542e UD	257	err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & msg->msg_flags
4a19542e UD	258	? O_CLOEXEC : 0);
1da177e4 LT	259	if (err < 0)
	260	break;
	261	new_fd = err;
	262	err = put_user(new_fd, cmfptr);
	263	if (err) {
	264	put_unused_fd(new_fd);
	265	break;
	266	}
	267	/* Bump the usage count and install the file. */
	268	get_file(fp[i]);
	269	fd_install(new_fd, fp[i]);
	270	}
	271
	272	if (i > 0)
	273	{
	274	int cmlen = CMSG_LEN(i*sizeof(int));
effee6a0	275	err = put_user(SOL_SOCKET, &cm->cmsg_level);
1da177e4 LT	276	if (!err)
	277	err = put_user(SCM_RIGHTS, &cm->cmsg_type);
	278	if (!err)
	279	err = put_user(cmlen, &cm->cmsg_len);
	280	if (!err) {
	281	cmlen = CMSG_SPACE(i*sizeof(int));
	282	msg->msg_control += cmlen;
	283	msg->msg_controllen -= cmlen;
	284	}
	285	}
	286	if (i < fdnum \|\| (fdnum && fdmax <= 0))
	287	msg->msg_flags \|= MSG_CTRUNC;
	288
	289	/*
	290	* All of the files that fit in the message have had their
	291	* usage counts incremented, so we just free the list.
	292	*/
	293	__scm_destroy(scm);
	294	}
	295
	296	struct scm_fp_list scm_fp_dup(struct scm_fp_list fpl)
	297	{
	298	struct scm_fp_list *new_fpl;
	299	int i;
	300
	301	if (!fpl)
	302	return NULL;
	303
	304	new_fpl = kmalloc(sizeof(*fpl), GFP_KERNEL);
	305	if (new_fpl) {
f8d570a4	306	INIT_LIST_HEAD(&new_fpl->list);
1da177e4 LT	307	for (i=fpl->count-1; i>=0; i--)
	308	get_file(fpl->fp[i]);
	309	memcpy(new_fpl, fpl, sizeof(*fpl));
	310	}
	311	return new_fpl;
	312	}
	313
	314	EXPORT_SYMBOL(__scm_destroy);
	315	EXPORT_SYMBOL(__scm_send);
	316	EXPORT_SYMBOL(put_cmsg);
	317	EXPORT_SYMBOL(scm_detach_fds);
	318	EXPORT_SYMBOL(scm_fp_dup);