[thirdparty/linux.git] / net / core / scm.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* scm.c - Socket level control messages processing.
 *
 * Author:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
 *              Alignment and value checking mods by Craig Metz
 */

#include <linux/module.h>
#include <linux/signal.h>
#include <linux/capability.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/sched/user.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_namespace.h>
#include <linux/pid.h>
#include <linux/nsproxy.h>
#include <linux/slab.h>
#include <linux/errqueue.h>

#include <linux/uaccess.h>

#include <net/protocol.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/compat.h>
#include <net/scm.h>
#include <net/cls_cgroup.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();
	kuid_t uid = make_kuid(cred->user_ns, creds->uid);
	kgid_t gid = make_kgid(cred->user_ns, creds->gid);

	if (!uid_valid(uid) || !gid_valid(gid))
		return -EINVAL;

	if ((creds->pid == task_tgid_vnr(current) ||
	     ns_capable(task_active_pid_ns(current)->user_ns, CAP_SYS_ADMIN)) &&
	    ((uid_eq(uid, cred->uid)   || uid_eq(uid, cred->euid) ||
	      uid_eq(uid, cred->suid)) || ns_capable(cred->user_ns, CAP_SETUID)) &&
	    ((gid_eq(gid, cred->gid)   || gid_eq(gid, cred->egid) ||
	      gid_eq(gid, cred->sgid)) || ns_capable(cred->user_ns, 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 - 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_ACCOUNT);
		if (!fpl)
			return -ENOMEM;
		*fplp = fpl;
		fpl->count = 0;
		fpl->max = SCM_MAX_FD;
		fpl->user = NULL;
	}
	fpp = &fpl->fp[fpl->count];

	if (fpl->count + num > fpl->max)
		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_raw(fd)))
			return -EBADF;
		*fpp++ = file;
		fpl->count++;
	}

	if (!fpl->user)
		fpl->user = get_uid(current_user());

	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]);
		free_uid(fpl->user);
		kfree(fpl);
	}
}
EXPORT_SYMBOL(__scm_destroy);

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

	for_each_cmsghdr(cmsg, msg) {
		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:
			if (!sock->ops || sock->ops->family != PF_UNIX)
				goto error;
			err=scm_fp_copy(cmsg, &p->fp);
			if (err<0)
				goto error;
			break;
		case SCM_CREDENTIALS:
		{
			struct ucred creds;
			kuid_t uid;
			kgid_t gid;
			if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
				goto error;
			memcpy(&creds, CMSG_DATA(cmsg), sizeof(struct ucred));
			err = scm_check_creds(&creds);
			if (err)
				goto error;

			p->creds.pid = creds.pid;
			if (!p->pid || pid_vnr(p->pid) != creds.pid) {
				struct pid *pid;
				err = -ESRCH;
				pid = find_get_pid(creds.pid);
				if (!pid)
					goto error;
				put_pid(p->pid);
				p->pid = pid;
			}

			err = -EINVAL;
			uid = make_kuid(current_user_ns(), creds.uid);
			gid = make_kgid(current_user_ns(), creds.gid);
			if (!uid_valid(uid) || !gid_valid(gid))
				goto error;

			p->creds.uid = uid;
			p->creds.gid = gid;
			break;
		}
		default:
			goto error;
		}
	}

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

error:
	scm_destroy(p);
	return err;
}
EXPORT_SYMBOL(__scm_send);

int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
{
	int cmlen = CMSG_LEN(len);

	if (msg->msg_flags & MSG_CMSG_COMPAT)
		return put_cmsg_compat(msg, level, type, len, data);

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

	if (msg->msg_control_is_user) {
		struct cmsghdr __user *cm = msg->msg_control_user;

		check_object_size(data, cmlen - sizeof(*cm), true);

		if (!user_write_access_begin(cm, cmlen))
			goto efault;

		unsafe_put_user(cmlen, &cm->cmsg_len, efault_end);
		unsafe_put_user(level, &cm->cmsg_level, efault_end);
		unsafe_put_user(type, &cm->cmsg_type, efault_end);
		unsafe_copy_to_user(CMSG_USER_DATA(cm), data,
				    cmlen - sizeof(*cm), efault_end);
		user_write_access_end();
	} 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));
	}

	cmlen = min(CMSG_SPACE(len), msg->msg_controllen);
	if (msg->msg_control_is_user)
		msg->msg_control_user += cmlen;
	else
		msg->msg_control += cmlen;
	msg->msg_controllen -= cmlen;
	return 0;

efault_end:
	user_write_access_end();
efault:
	return -EFAULT;
}
EXPORT_SYMBOL(put_cmsg);

void put_cmsg_scm_timestamping64(struct msghdr *msg, struct scm_timestamping_internal *tss_internal)
{
	struct scm_timestamping64 tss;
	int i;

	for (i = 0; i < ARRAY_SIZE(tss.ts); i++) {
		tss.ts[i].tv_sec = tss_internal->ts[i].tv_sec;
		tss.ts[i].tv_nsec = tss_internal->ts[i].tv_nsec;
	}

	put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMPING_NEW, sizeof(tss), &tss);
}
EXPORT_SYMBOL(put_cmsg_scm_timestamping64);

void put_cmsg_scm_timestamping(struct msghdr *msg, struct scm_timestamping_internal *tss_internal)
{
	struct scm_timestamping tss;
	int i;

	for (i = 0; i < ARRAY_SIZE(tss.ts); i++) {
		tss.ts[i].tv_sec = tss_internal->ts[i].tv_sec;
		tss.ts[i].tv_nsec = tss_internal->ts[i].tv_nsec;
	}

	put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMPING_OLD, sizeof(tss), &tss);
}
EXPORT_SYMBOL(put_cmsg_scm_timestamping);

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_user;
	unsigned 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;

	/* no use for FD passing from kernel space callers */
	if (WARN_ON_ONCE(!msg->msg_control_is_user))
		return;

	if (msg->msg_flags & MSG_CMSG_COMPAT) {
		scm_detach_fds_compat(msg, scm);
		return;
	}

	for (i = 0; i < fdmax; i++) {
		err = receive_fd_user(scm->fp->fp[i], cmsg_data + i, o_flags);
		if (err < 0)
			break;
	}

	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));
			if (msg->msg_controllen < cmlen)
				cmlen = msg->msg_controllen;
			msg->msg_control_user += cmlen;
			msg->msg_controllen -= cmlen;
		}
	}

	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.
	 */
	__scm_destroy(scm);
}
EXPORT_SYMBOL(scm_detach_fds);

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 = kmemdup(fpl, offsetof(struct scm_fp_list, fp[fpl->count]),
			  GFP_KERNEL_ACCOUNT);
	if (new_fpl) {
		for (i = 0; i < fpl->count; i++)
			get_file(fpl->fp[i]);
		new_fpl->max = new_fpl->count;
		new_fpl->user = get_uid(fpl->user);
	}
	return new_fpl;
}
EXPORT_SYMBOL(scm_fp_dup);
Commit	Line	Data
2874c5fd	1	// SPDX-License-Identifier: GPL-2.0-or-later
1da177e4 LT	2	/* scm.c - Socket level control messages processing.
	3	*
	4	* Author: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
	5	* Alignment and value checking mods by Craig Metz
1da177e4 LT	6	*/
	7
	8	#include <linux/module.h>
	9	#include <linux/signal.h>
4fc268d2	10	#include <linux/capability.h>
1da177e4 LT	11	#include <linux/errno.h>
1da177e4 LT	12	#include <linux/sched.h>
8703e8a4	13	#include <linux/sched/user.h>
1da177e4 LT	14	#include <linux/mm.h>
1da177e4 LT	15	#include <linux/kernel.h>
1da177e4 LT	16	#include <linux/stat.h>
	17	#include <linux/socket.h>
	18	#include <linux/file.h>
	19	#include <linux/fcntl.h>
	20	#include <linux/net.h>
	21	#include <linux/interrupt.h>
	22	#include <linux/netdevice.h>
	23	#include <linux/security.h>
92f28d97	24	#include <linux/pid_namespace.h>
b488893a PE	25	#include <linux/pid.h>
b488893a PE	26	#include <linux/nsproxy.h>
5a0e3ad6	27	#include <linux/slab.h>
9718475e	28	#include <linux/errqueue.h>
1da177e4	29
7c0f6ba6	30	#include <linux/uaccess.h>
1da177e4 LT	31
	32	#include <net/protocol.h>
	33	#include <linux/skbuff.h>
	34	#include <net/sock.h>
	35	#include <net/compat.h>
	36	#include <net/scm.h>
d8429506	37	#include <net/cls_cgroup.h>
1da177e4 LT	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();
b2e4f544 EB	48	kuid_t uid = make_kuid(cred->user_ns, creds->uid);
	49	kgid_t gid = make_kgid(cred->user_ns, creds->gid);
	50
	51	if (!uid_valid(uid) \|\| !gid_valid(gid))
	52	return -EINVAL;
b6dff3ec	53
92f28d97	54	if ((creds->pid == task_tgid_vnr(current) \|\|
d661684c	55	ns_capable(task_active_pid_ns(current)->user_ns, CAP_SYS_ADMIN)) &&
b2e4f544	56	((uid_eq(uid, cred->uid) \|\| uid_eq(uid, cred->euid) \|\|
c7b96acf	57	uid_eq(uid, cred->suid)) \|\| ns_capable(cred->user_ns, CAP_SETUID)) &&
b2e4f544	58	((gid_eq(gid, cred->gid) \|\| gid_eq(gid, cred->egid) \|\|
c7b96acf	59	gid_eq(gid, cred->sgid)) \|\| ns_capable(cred->user_ns, CAP_SETGID))) {
1da177e4 LT	60	return 0;
	61	}
	62	return -EPERM;
	63	}
	64
	65	static int scm_fp_copy(struct cmsghdr cmsg, struct scm_fp_list *fplp)
	66	{
	67	int fdp = (int)CMSG_DATA(cmsg);
	68	struct scm_fp_list fpl = fplp;
	69	struct file **fpp;
	70	int i, num;
	71
1ff8cebf	72	num = (cmsg->cmsg_len - sizeof(struct cmsghdr))/sizeof(int);
1da177e4 LT	73
	74	if (num <= 0)
	75	return 0;
	76
	77	if (num > SCM_MAX_FD)
	78	return -EINVAL;
	79
	80	if (!fpl)
	81	{
2c6ad20b	82	fpl = kmalloc(sizeof(struct scm_fp_list), GFP_KERNEL_ACCOUNT);
1da177e4 LT	83	if (!fpl)
	84	return -ENOMEM;
	85	*fplp = fpl;
	86	fpl->count = 0;
bba14de9	87	fpl->max = SCM_MAX_FD;
415e3d3e	88	fpl->user = NULL;
1da177e4 LT	89	}
	90	fpp = &fpl->fp[fpl->count];
	91
bba14de9	92	if (fpl->count + num > fpl->max)
1da177e4	93	return -EINVAL;
4ec93edb	94
1da177e4 LT	95	/*
	96	* Verify the descriptors and increment the usage count.
	97	*/
4ec93edb	98
1da177e4 LT	99	for (i=0; i< num; i++)
	100	{
	101	int fd = fdp[i];
	102	struct file *file;
	103
326be7b4	104	if (fd < 0 \|\| !(file = fget_raw(fd)))
1da177e4 LT	105	return -EBADF;
	106	*fpp++ = file;
	107	fpl->count++;
	108	}
415e3d3e HFS	109
	110	if (!fpl->user)
	111	fpl->user = get_uid(current_user());
	112
1da177e4 LT	113	return num;
	114	}
	115
	116	void __scm_destroy(struct scm_cookie *scm)
	117	{
	118	struct scm_fp_list *fpl = scm->fp;
	119	int i;
	120
	121	if (fpl) {
	122	scm->fp = NULL;
6120d3db AV	123	for (i=fpl->count-1; i>=0; i--)
6120d3db AV	124	fput(fpl->fp[i]);
415e3d3e	125	free_uid(fpl->user);
6120d3db	126	kfree(fpl);
1da177e4 LT	127	}
1da177e4 LT	128	}
9e34a5b5	129	EXPORT_SYMBOL(__scm_destroy);
1da177e4 LT	130
	131	int __scm_send(struct socket sock, struct msghdr msg, struct scm_cookie *p)
	132	{
	133	struct cmsghdr *cmsg;
	134	int err;
	135
f95b414e	136	for_each_cmsghdr(cmsg, msg) {
1da177e4 LT	137	err = -EINVAL;
	138
	139	/* Verify that cmsg_len is at least sizeof(struct cmsghdr) */
	140	/* The first check was omitted in <= 2.2.5. The reasoning was
	141	that parser checks cmsg_len in any case, so that
	142	additional check would be work duplication.
4ec93edb	143	But if cmsg_level is not SOL_SOCKET, we do not check
1da177e4 LT	144	for too short ancillary data object at all! Oops.
	145	OK, let's add it...
	146	*/
	147	if (!CMSG_OK(msg, cmsg))
	148	goto error;
	149
	150	if (cmsg->cmsg_level != SOL_SOCKET)
	151	continue;
	152
	153	switch (cmsg->cmsg_type)
	154	{
	155	case SCM_RIGHTS:
76dadd76 EB	156	if (!sock->ops \|\| sock->ops->family != PF_UNIX)
76dadd76 EB	157	goto error;
1da177e4 LT	158	err=scm_fp_copy(cmsg, &p->fp);
	159	if (err<0)
	160	goto error;
	161	break;
	162	case SCM_CREDENTIALS:
b2e4f544	163	{
dbe9a417	164	struct ucred creds;
b2e4f544 EB	165	kuid_t uid;
b2e4f544 EB	166	kgid_t gid;
1da177e4 LT	167	if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
1da177e4 LT	168	goto error;
dbe9a417 EB	169	memcpy(&creds, CMSG_DATA(cmsg), sizeof(struct ucred));
dbe9a417 EB	170	err = scm_check_creds(&creds);
1da177e4 LT	171	if (err)
1da177e4 LT	172	goto error;
257b5358	173
dbe9a417 EB	174	p->creds.pid = creds.pid;
dbe9a417 EB	175	if (!p->pid \|\| pid_vnr(p->pid) != creds.pid) {
257b5358 EB	176	struct pid *pid;
257b5358 EB	177	err = -ESRCH;
dbe9a417	178	pid = find_get_pid(creds.pid);
257b5358 EB	179	if (!pid)
	180	goto error;
	181	put_pid(p->pid);
	182	p->pid = pid;
	183	}
	184
b2e4f544	185	err = -EINVAL;
dbe9a417 EB	186	uid = make_kuid(current_user_ns(), creds.uid);
dbe9a417 EB	187	gid = make_kgid(current_user_ns(), creds.gid);
b2e4f544 EB	188	if (!uid_valid(uid) \|\| !gid_valid(gid))
	189	goto error;
	190
dbe9a417 EB	191	p->creds.uid = uid;
dbe9a417 EB	192	p->creds.gid = gid;
1da177e4	193	break;
b2e4f544	194	}
1da177e4 LT	195	default:
	196	goto error;
	197	}
	198	}
	199
	200	if (p->fp && !p->fp->count)
	201	{
	202	kfree(p->fp);
	203	p->fp = NULL;
	204	}
	205	return 0;
4ec93edb	206
1da177e4 LT	207	error:
	208	scm_destroy(p);
	209	return err;
	210	}
9e34a5b5	211	EXPORT_SYMBOL(__scm_send);
1da177e4 LT	212
	213	int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
	214	{
1da177e4	215	int cmlen = CMSG_LEN(len);
1da177e4	216
1f466e1f	217	if (msg->msg_flags & MSG_CMSG_COMPAT)
1da177e4 LT	218	return put_cmsg_compat(msg, level, type, len, data);
1da177e4 LT	219
1f466e1f	220	if (!msg->msg_control \|\| msg->msg_controllen < sizeof(struct cmsghdr)) {
1da177e4 LT	221	msg->msg_flags \|= MSG_CTRUNC;
	222	return 0; /* XXX: return error? check spec. */
	223	}
	224	if (msg->msg_controllen < cmlen) {
	225	msg->msg_flags \|= MSG_CTRUNC;
	226	cmlen = msg->msg_controllen;
	227	}
1f466e1f CH	228
	229	if (msg->msg_control_is_user) {
	230	struct cmsghdr __user *cm = msg->msg_control_user;
38ebcf50	231
5f1eb1ff ED	232	check_object_size(data, cmlen - sizeof(*cm), true);
5f1eb1ff ED	233
38ebcf50 ED	234	if (!user_write_access_begin(cm, cmlen))
	235	goto efault;
	236
e7ad33fa	237	unsafe_put_user(cmlen, &cm->cmsg_len, efault_end);
38ebcf50 ED	238	unsafe_put_user(level, &cm->cmsg_level, efault_end);
	239	unsafe_put_user(type, &cm->cmsg_type, efault_end);
	240	unsafe_copy_to_user(CMSG_USER_DATA(cm), data,
	241	cmlen - sizeof(*cm), efault_end);
	242	user_write_access_end();
1f466e1f CH	243	} else {
	244	struct cmsghdr *cm = msg->msg_control;
	245
	246	cm->cmsg_level = level;
	247	cm->cmsg_type = type;
	248	cm->cmsg_len = cmlen;
	249	memcpy(CMSG_DATA(cm), data, cmlen - sizeof(*cm));
	250	}
	251
	252	cmlen = min(CMSG_SPACE(len), msg->msg_controllen);
c39ef213 KB	253	if (msg->msg_control_is_user)
	254	msg->msg_control_user += cmlen;
	255	else
	256	msg->msg_control += cmlen;
1da177e4	257	msg->msg_controllen -= cmlen;
1f466e1f	258	return 0;
38ebcf50 ED	259
	260	efault_end:
	261	user_write_access_end();
	262	efault:
	263	return -EFAULT;
1da177e4	264	}
9e34a5b5	265	EXPORT_SYMBOL(put_cmsg);
1da177e4	266
9718475e DD	267	void put_cmsg_scm_timestamping64(struct msghdr msg, struct scm_timestamping_internal tss_internal)
	268	{
	269	struct scm_timestamping64 tss;
	270	int i;
	271
	272	for (i = 0; i < ARRAY_SIZE(tss.ts); i++) {
	273	tss.ts[i].tv_sec = tss_internal->ts[i].tv_sec;
	274	tss.ts[i].tv_nsec = tss_internal->ts[i].tv_nsec;
	275	}
	276
	277	put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMPING_NEW, sizeof(tss), &tss);
	278	}
	279	EXPORT_SYMBOL(put_cmsg_scm_timestamping64);
	280
	281	void put_cmsg_scm_timestamping(struct msghdr msg, struct scm_timestamping_internal tss_internal)
	282	{
	283	struct scm_timestamping tss;
	284	int i;
	285
0309f98f AB	286	for (i = 0; i < ARRAY_SIZE(tss.ts); i++) {
	287	tss.ts[i].tv_sec = tss_internal->ts[i].tv_sec;
	288	tss.ts[i].tv_nsec = tss_internal->ts[i].tv_nsec;
	289	}
9718475e DD	290
	291	put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMPING_OLD, sizeof(tss), &tss);
	292	}
	293	EXPORT_SYMBOL(put_cmsg_scm_timestamping);
	294
2618d530 CH	295	static int scm_max_fds(struct msghdr *msg)
	296	{
	297	if (msg->msg_controllen <= sizeof(struct cmsghdr))
	298	return 0;
	299	return (msg->msg_controllen - sizeof(struct cmsghdr)) / sizeof(int);
	300	}
	301
1da177e4 LT	302	void scm_detach_fds(struct msghdr msg, struct scm_cookie scm)
1da177e4 LT	303	{
c0029de5	304	struct cmsghdr __user *cm =
c39ef213	305	(__force struct cmsghdr __user *)msg->msg_control_user;
c0029de5	306	unsigned int o_flags = (msg->msg_flags & MSG_CMSG_CLOEXEC) ? O_CLOEXEC : 0;
2618d530 CH	307	int fdmax = min_t(int, scm_max_fds(msg), scm->fp->count);
2618d530 CH	308	int __user *cmsg_data = CMSG_USER_DATA(cm);
1da177e4 LT	309	int err = 0, i;
1da177e4 LT	310
c0029de5 KC	311	/* no use for FD passing from kernel space callers */
	312	if (WARN_ON_ONCE(!msg->msg_control_is_user))
	313	return;
	314
2618d530	315	if (msg->msg_flags & MSG_CMSG_COMPAT) {
1da177e4 LT	316	scm_detach_fds_compat(msg, scm);
	317	return;
	318	}
	319
2618d530	320	for (i = 0; i < fdmax; i++) {
66590610	321	err = receive_fd_user(scm->fp->fp[i], cmsg_data + i, o_flags);
deefa7f3	322	if (err < 0)
1da177e4	323	break;
1da177e4 LT	324	}
1da177e4 LT	325
c0029de5	326	if (i > 0) {
2618d530 CH	327	int cmlen = CMSG_LEN(i * sizeof(int));
2618d530 CH	328
effee6a0	329	err = put_user(SOL_SOCKET, &cm->cmsg_level);
1da177e4 LT	330	if (!err)
	331	err = put_user(SCM_RIGHTS, &cm->cmsg_type);
	332	if (!err)
	333	err = put_user(cmlen, &cm->cmsg_len);
	334	if (!err) {
2618d530	335	cmlen = CMSG_SPACE(i * sizeof(int));
6900317f DB	336	if (msg->msg_controllen < cmlen)
6900317f DB	337	cmlen = msg->msg_controllen;
c39ef213	338	msg->msg_control_user += cmlen;
1da177e4 LT	339	msg->msg_controllen -= cmlen;
	340	}
	341	}
2618d530 CH	342
2618d530 CH	343	if (i < scm->fp->count \|\| (scm->fp->count && fdmax <= 0))
1da177e4 LT	344	msg->msg_flags \|= MSG_CTRUNC;
	345
	346	/*
2618d530 CH	347	* All of the files that fit in the message have had their usage counts
2618d530 CH	348	* incremented, so we just free the list.
1da177e4 LT	349	*/
	350	__scm_destroy(scm);
	351	}
9e34a5b5	352	EXPORT_SYMBOL(scm_detach_fds);
1da177e4 LT	353
	354	struct scm_fp_list scm_fp_dup(struct scm_fp_list fpl)
	355	{
	356	struct scm_fp_list *new_fpl;
	357	int i;
	358
	359	if (!fpl)
	360	return NULL;
	361
bba14de9	362	new_fpl = kmemdup(fpl, offsetof(struct scm_fp_list, fp[fpl->count]),
2c6ad20b	363	GFP_KERNEL_ACCOUNT);
1da177e4	364	if (new_fpl) {
bba14de9	365	for (i = 0; i < fpl->count; i++)
1da177e4	366	get_file(fpl->fp[i]);
bba14de9	367	new_fpl->max = new_fpl->count;
415e3d3e	368	new_fpl->user = get_uid(fpl->user);
1da177e4 LT	369	}
	370	return new_fpl;
	371	}
1da177e4	372	EXPORT_SYMBOL(scm_fp_dup);