[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)
{
	if ((creds->pid == task_tgid_vnr(current) || capable(CAP_SYS_ADMIN)) &&
	    ((creds->uid == current->uid || creds->uid == current->euid ||
	      creds->uid == current->suid) || capable(CAP_SETUID)) &&
	    ((creds->gid == current->gid || creds->gid == current->egid ||
	      creds->gid == current->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;
		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;
		for (i=fpl->count-1; i>=0; i--)
			fput(fpl->fp[i]);
		kfree(fpl);
	}
}

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) {
		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	{
b488893a	47	if ((creds->pid == task_tgid_vnr(current) \|\| capable(CAP_SYS_ADMIN)) &&
1da177e4 LT	48	((creds->uid == current->uid \|\| creds->uid == current->euid \|\|
	49	creds->uid == current->suid) \|\| capable(CAP_SETUID)) &&
	50	((creds->gid == current->gid \|\| creds->gid == current->egid \|\|
	51	creds->gid == current->sgid) \|\| capable(CAP_SETGID))) {
	52	return 0;
	53	}
	54	return -EPERM;
	55	}
	56
	57	static int scm_fp_copy(struct cmsghdr cmsg, struct scm_fp_list *fplp)
	58	{
	59	int fdp = (int)CMSG_DATA(cmsg);
	60	struct scm_fp_list fpl = fplp;
	61	struct file **fpp;
	62	int i, num;
	63
	64	num = (cmsg->cmsg_len - CMSG_ALIGN(sizeof(struct cmsghdr)))/sizeof(int);
	65
	66	if (num <= 0)
	67	return 0;
	68
	69	if (num > SCM_MAX_FD)
	70	return -EINVAL;
	71
	72	if (!fpl)
	73	{
	74	fpl = kmalloc(sizeof(struct scm_fp_list), GFP_KERNEL);
	75	if (!fpl)
	76	return -ENOMEM;
	77	*fplp = fpl;
	78	fpl->count = 0;
	79	}
	80	fpp = &fpl->fp[fpl->count];
	81
	82	if (fpl->count + num > SCM_MAX_FD)
	83	return -EINVAL;
4ec93edb	84
1da177e4 LT	85	/*
	86	* Verify the descriptors and increment the usage count.
	87	*/
4ec93edb	88
1da177e4 LT	89	for (i=0; i< num; i++)
	90	{
	91	int fd = fdp[i];
	92	struct file *file;
	93
	94	if (fd < 0 \|\| !(file = fget(fd)))
	95	return -EBADF;
	96	*fpp++ = file;
	97	fpl->count++;
	98	}
	99	return num;
	100	}
	101
	102	void __scm_destroy(struct scm_cookie *scm)
	103	{
	104	struct scm_fp_list *fpl = scm->fp;
	105	int i;
	106
	107	if (fpl) {
	108	scm->fp = NULL;
	109	for (i=fpl->count-1; i>=0; i--)
	110	fput(fpl->fp[i]);
	111	kfree(fpl);
	112	}
	113	}
	114
	115	int __scm_send(struct socket sock, struct msghdr msg, struct scm_cookie *p)
	116	{
	117	struct cmsghdr *cmsg;
	118	int err;
	119
	120	for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg))
	121	{
	122	err = -EINVAL;
	123
	124	/* Verify that cmsg_len is at least sizeof(struct cmsghdr) */
	125	/* The first check was omitted in <= 2.2.5. The reasoning was
	126	that parser checks cmsg_len in any case, so that
	127	additional check would be work duplication.
4ec93edb	128	But if cmsg_level is not SOL_SOCKET, we do not check
1da177e4 LT	129	for too short ancillary data object at all! Oops.
	130	OK, let's add it...
	131	*/
	132	if (!CMSG_OK(msg, cmsg))
	133	goto error;
	134
	135	if (cmsg->cmsg_level != SOL_SOCKET)
	136	continue;
	137
	138	switch (cmsg->cmsg_type)
	139	{
	140	case SCM_RIGHTS:
	141	err=scm_fp_copy(cmsg, &p->fp);
	142	if (err<0)
	143	goto error;
	144	break;
	145	case SCM_CREDENTIALS:
	146	if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
	147	goto error;
	148	memcpy(&p->creds, CMSG_DATA(cmsg), sizeof(struct ucred));
	149	err = scm_check_creds(&p->creds);
	150	if (err)
	151	goto error;
	152	break;
	153	default:
	154	goto error;
	155	}
	156	}
	157
	158	if (p->fp && !p->fp->count)
	159	{
	160	kfree(p->fp);
	161	p->fp = NULL;
	162	}
	163	return 0;
4ec93edb	164
1da177e4 LT	165	error:
	166	scm_destroy(p);
	167	return err;
	168	}
	169
	170	int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
	171	{
cfcabdcc SH	172	struct cmsghdr __user *cm
cfcabdcc SH	173	= (__force struct cmsghdr __user *)msg->msg_control;
1da177e4 LT	174	struct cmsghdr cmhdr;
	175	int cmlen = CMSG_LEN(len);
	176	int err;
	177
	178	if (MSG_CMSG_COMPAT & msg->msg_flags)
	179	return put_cmsg_compat(msg, level, type, len, data);
	180
	181	if (cm==NULL \|\| msg->msg_controllen < sizeof(*cm)) {
	182	msg->msg_flags \|= MSG_CTRUNC;
	183	return 0; /* XXX: return error? check spec. */
	184	}
	185	if (msg->msg_controllen < cmlen) {
	186	msg->msg_flags \|= MSG_CTRUNC;
	187	cmlen = msg->msg_controllen;
	188	}
	189	cmhdr.cmsg_level = level;
	190	cmhdr.cmsg_type = type;
	191	cmhdr.cmsg_len = cmlen;
	192
	193	err = -EFAULT;
	194	if (copy_to_user(cm, &cmhdr, sizeof cmhdr))
4ec93edb	195	goto out;
1da177e4 LT	196	if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr)))
	197	goto out;
	198	cmlen = CMSG_SPACE(len);
1ac70e7a WY	199	if (msg->msg_controllen < cmlen)
1ac70e7a WY	200	cmlen = msg->msg_controllen;
1da177e4 LT	201	msg->msg_control += cmlen;
	202	msg->msg_controllen -= cmlen;
	203	err = 0;
	204	out:
	205	return err;
	206	}
	207
	208	void scm_detach_fds(struct msghdr msg, struct scm_cookie scm)
	209	{
cfcabdcc SH	210	struct cmsghdr __user *cm
cfcabdcc SH	211	= (__force struct cmsghdr __user*)msg->msg_control;
1da177e4 LT	212
	213	int fdmax = 0;
	214	int fdnum = scm->fp->count;
	215	struct file **fp = scm->fp->fp;
	216	int __user *cmfptr;
	217	int err = 0, i;
	218
	219	if (MSG_CMSG_COMPAT & msg->msg_flags) {
	220	scm_detach_fds_compat(msg, scm);
	221	return;
	222	}
	223
	224	if (msg->msg_controllen > sizeof(struct cmsghdr))
	225	fdmax = ((msg->msg_controllen - sizeof(struct cmsghdr))
	226	/ sizeof(int));
	227
	228	if (fdnum < fdmax)
	229	fdmax = fdnum;
	230
cfcabdcc SH	231	for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax;
cfcabdcc SH	232	i++, cmfptr++)
1da177e4 LT	233	{
	234	int new_fd;
	235	err = security_file_receive(fp[i]);
	236	if (err)
	237	break;
4a19542e UD	238	err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & msg->msg_flags
4a19542e UD	239	? O_CLOEXEC : 0);
1da177e4 LT	240	if (err < 0)
	241	break;
	242	new_fd = err;
	243	err = put_user(new_fd, cmfptr);
	244	if (err) {
	245	put_unused_fd(new_fd);
	246	break;
	247	}
	248	/* Bump the usage count and install the file. */
	249	get_file(fp[i]);
	250	fd_install(new_fd, fp[i]);
	251	}
	252
	253	if (i > 0)
	254	{
	255	int cmlen = CMSG_LEN(i*sizeof(int));
effee6a0	256	err = put_user(SOL_SOCKET, &cm->cmsg_level);
1da177e4 LT	257	if (!err)
	258	err = put_user(SCM_RIGHTS, &cm->cmsg_type);
	259	if (!err)
	260	err = put_user(cmlen, &cm->cmsg_len);
	261	if (!err) {
	262	cmlen = CMSG_SPACE(i*sizeof(int));
	263	msg->msg_control += cmlen;
	264	msg->msg_controllen -= cmlen;
	265	}
	266	}
	267	if (i < fdnum \|\| (fdnum && fdmax <= 0))
	268	msg->msg_flags \|= MSG_CTRUNC;
	269
	270	/*
	271	* All of the files that fit in the message have had their
	272	* usage counts incremented, so we just free the list.
	273	*/
	274	__scm_destroy(scm);
	275	}
	276
	277	struct scm_fp_list scm_fp_dup(struct scm_fp_list fpl)
	278	{
	279	struct scm_fp_list *new_fpl;
	280	int i;
	281
	282	if (!fpl)
	283	return NULL;
	284
	285	new_fpl = kmalloc(sizeof(*fpl), GFP_KERNEL);
	286	if (new_fpl) {
	287	for (i=fpl->count-1; i>=0; i--)
	288	get_file(fpl->fp[i]);
	289	memcpy(new_fpl, fpl, sizeof(*fpl));
	290	}
	291	return new_fpl;
	292	}
	293
	294	EXPORT_SYMBOL(__scm_destroy);
	295	EXPORT_SYMBOL(__scm_send);
	296	EXPORT_SYMBOL(put_cmsg);
	297	EXPORT_SYMBOL(scm_detach_fds);
	298	EXPORT_SYMBOL(scm_fp_dup);