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v4.17
 
  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>
 14#include <linux/capability.h>
 15#include <linux/errno.h>
 16#include <linux/sched.h>
 17#include <linux/sched/user.h>
 18#include <linux/mm.h>
 19#include <linux/kernel.h>
 20#include <linux/stat.h>
 21#include <linux/socket.h>
 22#include <linux/file.h>
 23#include <linux/fcntl.h>
 24#include <linux/net.h>
 25#include <linux/interrupt.h>
 26#include <linux/netdevice.h>
 27#include <linux/security.h>
 28#include <linux/pid_namespace.h>
 29#include <linux/pid.h>
 30#include <linux/nsproxy.h>
 31#include <linux/slab.h>
 
 
 32
 33#include <linux/uaccess.h>
 34
 35#include <net/protocol.h>
 36#include <linux/skbuff.h>
 37#include <net/sock.h>
 38#include <net/compat.h>
 39#include <net/scm.h>
 40#include <net/cls_cgroup.h>
 
 41
 42
 43/*
 44 *	Only allow a user to send credentials, that they could set with
 45 *	setu(g)id.
 46 */
 47
 48static __inline__ int scm_check_creds(struct ucred *creds)
 49{
 50	const struct cred *cred = current_cred();
 51	kuid_t uid = make_kuid(cred->user_ns, creds->uid);
 52	kgid_t gid = make_kgid(cred->user_ns, creds->gid);
 53
 54	if (!uid_valid(uid) || !gid_valid(gid))
 55		return -EINVAL;
 56
 57	if ((creds->pid == task_tgid_vnr(current) ||
 58	     ns_capable(task_active_pid_ns(current)->user_ns, CAP_SYS_ADMIN)) &&
 59	    ((uid_eq(uid, cred->uid)   || uid_eq(uid, cred->euid) ||
 60	      uid_eq(uid, cred->suid)) || ns_capable(cred->user_ns, CAP_SETUID)) &&
 61	    ((gid_eq(gid, cred->gid)   || gid_eq(gid, cred->egid) ||
 62	      gid_eq(gid, cred->sgid)) || ns_capable(cred->user_ns, CAP_SETGID))) {
 63	       return 0;
 64	}
 65	return -EPERM;
 66}
 67
 68static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp)
 69{
 70	int *fdp = (int*)CMSG_DATA(cmsg);
 71	struct scm_fp_list *fpl = *fplp;
 72	struct file **fpp;
 73	int i, num;
 74
 75	num = (cmsg->cmsg_len - sizeof(struct cmsghdr))/sizeof(int);
 76
 77	if (num <= 0)
 78		return 0;
 79
 80	if (num > SCM_MAX_FD)
 81		return -EINVAL;
 82
 83	if (!fpl)
 84	{
 85		fpl = kmalloc(sizeof(struct scm_fp_list), GFP_KERNEL);
 86		if (!fpl)
 87			return -ENOMEM;
 88		*fplp = fpl;
 89		fpl->count = 0;
 
 90		fpl->max = SCM_MAX_FD;
 91		fpl->user = NULL;
 92	}
 93	fpp = &fpl->fp[fpl->count];
 94
 95	if (fpl->count + num > fpl->max)
 96		return -EINVAL;
 97
 98	/*
 99	 *	Verify the descriptors and increment the usage count.
100	 */
101
102	for (i=0; i< num; i++)
103	{
104		int fd = fdp[i];
105		struct file *file;
106
107		if (fd < 0 || !(file = fget_raw(fd)))
108			return -EBADF;
 
 
 
 
 
 
 
 
109		*fpp++ = file;
110		fpl->count++;
111	}
112
113	if (!fpl->user)
114		fpl->user = get_uid(current_user());
115
116	return num;
117}
118
119void __scm_destroy(struct scm_cookie *scm)
120{
121	struct scm_fp_list *fpl = scm->fp;
122	int i;
123
124	if (fpl) {
125		scm->fp = NULL;
126		for (i=fpl->count-1; i>=0; i--)
127			fput(fpl->fp[i]);
128		free_uid(fpl->user);
129		kfree(fpl);
130	}
131}
132EXPORT_SYMBOL(__scm_destroy);
133
134int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
135{
 
136	struct cmsghdr *cmsg;
137	int err;
138
139	for_each_cmsghdr(cmsg, msg) {
140		err = -EINVAL;
141
142		/* Verify that cmsg_len is at least sizeof(struct cmsghdr) */
143		/* The first check was omitted in <= 2.2.5. The reasoning was
144		   that parser checks cmsg_len in any case, so that
145		   additional check would be work duplication.
146		   But if cmsg_level is not SOL_SOCKET, we do not check
147		   for too short ancillary data object at all! Oops.
148		   OK, let's add it...
149		 */
150		if (!CMSG_OK(msg, cmsg))
151			goto error;
152
153		if (cmsg->cmsg_level != SOL_SOCKET)
154			continue;
155
156		switch (cmsg->cmsg_type)
157		{
158		case SCM_RIGHTS:
159			if (!sock->ops || sock->ops->family != PF_UNIX)
160				goto error;
161			err=scm_fp_copy(cmsg, &p->fp);
162			if (err<0)
163				goto error;
164			break;
165		case SCM_CREDENTIALS:
166		{
167			struct ucred creds;
168			kuid_t uid;
169			kgid_t gid;
170			if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
171				goto error;
172			memcpy(&creds, CMSG_DATA(cmsg), sizeof(struct ucred));
173			err = scm_check_creds(&creds);
174			if (err)
175				goto error;
176
177			p->creds.pid = creds.pid;
178			if (!p->pid || pid_vnr(p->pid) != creds.pid) {
179				struct pid *pid;
180				err = -ESRCH;
181				pid = find_get_pid(creds.pid);
182				if (!pid)
183					goto error;
184				put_pid(p->pid);
185				p->pid = pid;
186			}
187
188			err = -EINVAL;
189			uid = make_kuid(current_user_ns(), creds.uid);
190			gid = make_kgid(current_user_ns(), creds.gid);
191			if (!uid_valid(uid) || !gid_valid(gid))
192				goto error;
193
194			p->creds.uid = uid;
195			p->creds.gid = gid;
196			break;
197		}
198		default:
199			goto error;
200		}
201	}
202
203	if (p->fp && !p->fp->count)
204	{
205		kfree(p->fp);
206		p->fp = NULL;
207	}
208	return 0;
209
210error:
211	scm_destroy(p);
212	return err;
213}
214EXPORT_SYMBOL(__scm_send);
215
216int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
217{
218	struct cmsghdr __user *cm
219		= (__force struct cmsghdr __user *)msg->msg_control;
220	struct cmsghdr cmhdr;
221	int cmlen = CMSG_LEN(len);
222	int err;
223
224	if (MSG_CMSG_COMPAT & msg->msg_flags)
225		return put_cmsg_compat(msg, level, type, len, data);
226
227	if (cm==NULL || msg->msg_controllen < sizeof(*cm)) {
228		msg->msg_flags |= MSG_CTRUNC;
229		return 0; /* XXX: return error? check spec. */
230	}
231	if (msg->msg_controllen < cmlen) {
232		msg->msg_flags |= MSG_CTRUNC;
233		cmlen = msg->msg_controllen;
234	}
235	cmhdr.cmsg_level = level;
236	cmhdr.cmsg_type = type;
237	cmhdr.cmsg_len = cmlen;
238
239	err = -EFAULT;
240	if (copy_to_user(cm, &cmhdr, sizeof cmhdr))
241		goto out;
242	if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr)))
243		goto out;
244	cmlen = CMSG_SPACE(len);
245	if (msg->msg_controllen < cmlen)
246		cmlen = msg->msg_controllen;
247	msg->msg_control += cmlen;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
248	msg->msg_controllen -= cmlen;
249	err = 0;
250out:
251	return err;
 
 
 
252}
253EXPORT_SYMBOL(put_cmsg);
254
255void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
256{
257	struct cmsghdr __user *cm
258		= (__force struct cmsghdr __user*)msg->msg_control;
259
260	int fdmax = 0;
261	int fdnum = scm->fp->count;
262	struct file **fp = scm->fp->fp;
263	int __user *cmfptr;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
264	int err = 0, i;
265
266	if (MSG_CMSG_COMPAT & msg->msg_flags) {
 
 
 
 
267		scm_detach_fds_compat(msg, scm);
268		return;
269	}
270
271	if (msg->msg_controllen > sizeof(struct cmsghdr))
272		fdmax = ((msg->msg_controllen - sizeof(struct cmsghdr))
273			 / sizeof(int));
274
275	if (fdnum < fdmax)
276		fdmax = fdnum;
277
278	for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax;
279	     i++, cmfptr++)
280	{
281		struct socket *sock;
282		int new_fd;
283		err = security_file_receive(fp[i]);
284		if (err)
285			break;
286		err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & msg->msg_flags
287					  ? O_CLOEXEC : 0);
288		if (err < 0)
289			break;
290		new_fd = err;
291		err = put_user(new_fd, cmfptr);
292		if (err) {
293			put_unused_fd(new_fd);
294			break;
295		}
296		/* Bump the usage count and install the file. */
297		sock = sock_from_file(fp[i], &err);
298		if (sock) {
299			sock_update_netprioidx(&sock->sk->sk_cgrp_data);
300			sock_update_classid(&sock->sk->sk_cgrp_data);
301		}
302		fd_install(new_fd, get_file(fp[i]));
303	}
304
305	if (i > 0)
306	{
307		int cmlen = CMSG_LEN(i*sizeof(int));
308		err = put_user(SOL_SOCKET, &cm->cmsg_level);
309		if (!err)
310			err = put_user(SCM_RIGHTS, &cm->cmsg_type);
311		if (!err)
312			err = put_user(cmlen, &cm->cmsg_len);
313		if (!err) {
314			cmlen = CMSG_SPACE(i*sizeof(int));
315			if (msg->msg_controllen < cmlen)
316				cmlen = msg->msg_controllen;
317			msg->msg_control += cmlen;
318			msg->msg_controllen -= cmlen;
319		}
320	}
321	if (i < fdnum || (fdnum && fdmax <= 0))
 
322		msg->msg_flags |= MSG_CTRUNC;
323
324	/*
325	 * All of the files that fit in the message have had their
326	 * usage counts incremented, so we just free the list.
327	 */
328	__scm_destroy(scm);
329}
330EXPORT_SYMBOL(scm_detach_fds);
331
332struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
333{
334	struct scm_fp_list *new_fpl;
335	int i;
336
337	if (!fpl)
338		return NULL;
339
340	new_fpl = kmemdup(fpl, offsetof(struct scm_fp_list, fp[fpl->count]),
341			  GFP_KERNEL);
342	if (new_fpl) {
343		for (i = 0; i < fpl->count; i++)
344			get_file(fpl->fp[i]);
345		new_fpl->max = new_fpl->count;
346		new_fpl->user = get_uid(fpl->user);
347	}
348	return new_fpl;
349}
350EXPORT_SYMBOL(scm_fp_dup);
v6.9.4
  1// SPDX-License-Identifier: GPL-2.0-or-later
  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
 
 
 
 
 
  6 */
  7
  8#include <linux/module.h>
  9#include <linux/signal.h>
 10#include <linux/capability.h>
 11#include <linux/errno.h>
 12#include <linux/sched.h>
 13#include <linux/sched/user.h>
 14#include <linux/mm.h>
 15#include <linux/kernel.h>
 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>
 24#include <linux/pid_namespace.h>
 25#include <linux/pid.h>
 26#include <linux/nsproxy.h>
 27#include <linux/slab.h>
 28#include <linux/errqueue.h>
 29#include <linux/io_uring.h>
 30
 31#include <linux/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#include <net/cls_cgroup.h>
 39#include <net/af_unix.h>
 40
 41
 42/*
 43 *	Only allow a user to send credentials, that they could set with
 44 *	setu(g)id.
 45 */
 46
 47static __inline__ int scm_check_creds(struct ucred *creds)
 48{
 49	const struct cred *cred = current_cred();
 50	kuid_t uid = make_kuid(cred->user_ns, creds->uid);
 51	kgid_t gid = make_kgid(cred->user_ns, creds->gid);
 52
 53	if (!uid_valid(uid) || !gid_valid(gid))
 54		return -EINVAL;
 55
 56	if ((creds->pid == task_tgid_vnr(current) ||
 57	     ns_capable(task_active_pid_ns(current)->user_ns, CAP_SYS_ADMIN)) &&
 58	    ((uid_eq(uid, cred->uid)   || uid_eq(uid, cred->euid) ||
 59	      uid_eq(uid, cred->suid)) || ns_capable(cred->user_ns, CAP_SETUID)) &&
 60	    ((gid_eq(gid, cred->gid)   || gid_eq(gid, cred->egid) ||
 61	      gid_eq(gid, cred->sgid)) || ns_capable(cred->user_ns, CAP_SETGID))) {
 62	       return 0;
 63	}
 64	return -EPERM;
 65}
 66
 67static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp)
 68{
 69	int *fdp = (int*)CMSG_DATA(cmsg);
 70	struct scm_fp_list *fpl = *fplp;
 71	struct file **fpp;
 72	int i, num;
 73
 74	num = (cmsg->cmsg_len - sizeof(struct cmsghdr))/sizeof(int);
 75
 76	if (num <= 0)
 77		return 0;
 78
 79	if (num > SCM_MAX_FD)
 80		return -EINVAL;
 81
 82	if (!fpl)
 83	{
 84		fpl = kmalloc(sizeof(struct scm_fp_list), GFP_KERNEL_ACCOUNT);
 85		if (!fpl)
 86			return -ENOMEM;
 87		*fplp = fpl;
 88		fpl->count = 0;
 89		fpl->count_unix = 0;
 90		fpl->max = SCM_MAX_FD;
 91		fpl->user = NULL;
 92	}
 93	fpp = &fpl->fp[fpl->count];
 94
 95	if (fpl->count + num > fpl->max)
 96		return -EINVAL;
 97
 98	/*
 99	 *	Verify the descriptors and increment the usage count.
100	 */
101
102	for (i=0; i< num; i++)
103	{
104		int fd = fdp[i];
105		struct file *file;
106
107		if (fd < 0 || !(file = fget_raw(fd)))
108			return -EBADF;
109		/* don't allow io_uring files */
110		if (io_is_uring_fops(file)) {
111			fput(file);
112			return -EINVAL;
113		}
114		if (unix_get_socket(file))
115			fpl->count_unix++;
116
117		*fpp++ = file;
118		fpl->count++;
119	}
120
121	if (!fpl->user)
122		fpl->user = get_uid(current_user());
123
124	return num;
125}
126
127void __scm_destroy(struct scm_cookie *scm)
128{
129	struct scm_fp_list *fpl = scm->fp;
130	int i;
131
132	if (fpl) {
133		scm->fp = NULL;
134		for (i=fpl->count-1; i>=0; i--)
135			fput(fpl->fp[i]);
136		free_uid(fpl->user);
137		kfree(fpl);
138	}
139}
140EXPORT_SYMBOL(__scm_destroy);
141
142int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
143{
144	const struct proto_ops *ops = READ_ONCE(sock->ops);
145	struct cmsghdr *cmsg;
146	int err;
147
148	for_each_cmsghdr(cmsg, msg) {
149		err = -EINVAL;
150
151		/* Verify that cmsg_len is at least sizeof(struct cmsghdr) */
152		/* The first check was omitted in <= 2.2.5. The reasoning was
153		   that parser checks cmsg_len in any case, so that
154		   additional check would be work duplication.
155		   But if cmsg_level is not SOL_SOCKET, we do not check
156		   for too short ancillary data object at all! Oops.
157		   OK, let's add it...
158		 */
159		if (!CMSG_OK(msg, cmsg))
160			goto error;
161
162		if (cmsg->cmsg_level != SOL_SOCKET)
163			continue;
164
165		switch (cmsg->cmsg_type)
166		{
167		case SCM_RIGHTS:
168			if (!ops || ops->family != PF_UNIX)
169				goto error;
170			err=scm_fp_copy(cmsg, &p->fp);
171			if (err<0)
172				goto error;
173			break;
174		case SCM_CREDENTIALS:
175		{
176			struct ucred creds;
177			kuid_t uid;
178			kgid_t gid;
179			if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
180				goto error;
181			memcpy(&creds, CMSG_DATA(cmsg), sizeof(struct ucred));
182			err = scm_check_creds(&creds);
183			if (err)
184				goto error;
185
186			p->creds.pid = creds.pid;
187			if (!p->pid || pid_vnr(p->pid) != creds.pid) {
188				struct pid *pid;
189				err = -ESRCH;
190				pid = find_get_pid(creds.pid);
191				if (!pid)
192					goto error;
193				put_pid(p->pid);
194				p->pid = pid;
195			}
196
197			err = -EINVAL;
198			uid = make_kuid(current_user_ns(), creds.uid);
199			gid = make_kgid(current_user_ns(), creds.gid);
200			if (!uid_valid(uid) || !gid_valid(gid))
201				goto error;
202
203			p->creds.uid = uid;
204			p->creds.gid = gid;
205			break;
206		}
207		default:
208			goto error;
209		}
210	}
211
212	if (p->fp && !p->fp->count)
213	{
214		kfree(p->fp);
215		p->fp = NULL;
216	}
217	return 0;
218
219error:
220	scm_destroy(p);
221	return err;
222}
223EXPORT_SYMBOL(__scm_send);
224
225int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
226{
 
 
 
227	int cmlen = CMSG_LEN(len);
 
228
229	if (msg->msg_flags & MSG_CMSG_COMPAT)
230		return put_cmsg_compat(msg, level, type, len, data);
231
232	if (!msg->msg_control || msg->msg_controllen < sizeof(struct cmsghdr)) {
233		msg->msg_flags |= MSG_CTRUNC;
234		return 0; /* XXX: return error? check spec. */
235	}
236	if (msg->msg_controllen < cmlen) {
237		msg->msg_flags |= MSG_CTRUNC;
238		cmlen = msg->msg_controllen;
239	}
240
241	if (msg->msg_control_is_user) {
242		struct cmsghdr __user *cm = msg->msg_control_user;
243
244		check_object_size(data, cmlen - sizeof(*cm), true);
245
246		if (!user_write_access_begin(cm, cmlen))
247			goto efault;
248
249		unsafe_put_user(cmlen, &cm->cmsg_len, efault_end);
250		unsafe_put_user(level, &cm->cmsg_level, efault_end);
251		unsafe_put_user(type, &cm->cmsg_type, efault_end);
252		unsafe_copy_to_user(CMSG_USER_DATA(cm), data,
253				    cmlen - sizeof(*cm), efault_end);
254		user_write_access_end();
255	} else {
256		struct cmsghdr *cm = msg->msg_control;
257
258		cm->cmsg_level = level;
259		cm->cmsg_type = type;
260		cm->cmsg_len = cmlen;
261		memcpy(CMSG_DATA(cm), data, cmlen - sizeof(*cm));
262	}
263
264	cmlen = min(CMSG_SPACE(len), msg->msg_controllen);
265	if (msg->msg_control_is_user)
266		msg->msg_control_user += cmlen;
267	else
268		msg->msg_control += cmlen;
269	msg->msg_controllen -= cmlen;
270	return 0;
271
272efault_end:
273	user_write_access_end();
274efault:
275	return -EFAULT;
276}
277EXPORT_SYMBOL(put_cmsg);
278
279void put_cmsg_scm_timestamping64(struct msghdr *msg, struct scm_timestamping_internal *tss_internal)
280{
281	struct scm_timestamping64 tss;
282	int i;
283
284	for (i = 0; i < ARRAY_SIZE(tss.ts); i++) {
285		tss.ts[i].tv_sec = tss_internal->ts[i].tv_sec;
286		tss.ts[i].tv_nsec = tss_internal->ts[i].tv_nsec;
287	}
288
289	put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMPING_NEW, sizeof(tss), &tss);
290}
291EXPORT_SYMBOL(put_cmsg_scm_timestamping64);
292
293void put_cmsg_scm_timestamping(struct msghdr *msg, struct scm_timestamping_internal *tss_internal)
294{
295	struct scm_timestamping tss;
296	int i;
297
298	for (i = 0; i < ARRAY_SIZE(tss.ts); i++) {
299		tss.ts[i].tv_sec = tss_internal->ts[i].tv_sec;
300		tss.ts[i].tv_nsec = tss_internal->ts[i].tv_nsec;
301	}
302
303	put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMPING_OLD, sizeof(tss), &tss);
304}
305EXPORT_SYMBOL(put_cmsg_scm_timestamping);
306
307static int scm_max_fds(struct msghdr *msg)
308{
309	if (msg->msg_controllen <= sizeof(struct cmsghdr))
310		return 0;
311	return (msg->msg_controllen - sizeof(struct cmsghdr)) / sizeof(int);
312}
313
314void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
315{
316	struct cmsghdr __user *cm =
317		(__force struct cmsghdr __user *)msg->msg_control_user;
318	unsigned int o_flags = (msg->msg_flags & MSG_CMSG_CLOEXEC) ? O_CLOEXEC : 0;
319	int fdmax = min_t(int, scm_max_fds(msg), scm->fp->count);
320	int __user *cmsg_data = CMSG_USER_DATA(cm);
321	int err = 0, i;
322
323	/* no use for FD passing from kernel space callers */
324	if (WARN_ON_ONCE(!msg->msg_control_is_user))
325		return;
326
327	if (msg->msg_flags & MSG_CMSG_COMPAT) {
328		scm_detach_fds_compat(msg, scm);
329		return;
330	}
331
332	for (i = 0; i < fdmax; i++) {
333		err = scm_recv_one_fd(scm->fp->fp[i], cmsg_data + i, o_flags);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
334		if (err < 0)
335			break;
 
 
 
 
 
 
 
 
 
 
 
 
 
336	}
337
338	if (i > 0) {
339		int cmlen = CMSG_LEN(i * sizeof(int));
340
341		err = put_user(SOL_SOCKET, &cm->cmsg_level);
342		if (!err)
343			err = put_user(SCM_RIGHTS, &cm->cmsg_type);
344		if (!err)
345			err = put_user(cmlen, &cm->cmsg_len);
346		if (!err) {
347			cmlen = CMSG_SPACE(i * sizeof(int));
348			if (msg->msg_controllen < cmlen)
349				cmlen = msg->msg_controllen;
350			msg->msg_control_user += cmlen;
351			msg->msg_controllen -= cmlen;
352		}
353	}
354
355	if (i < scm->fp->count || (scm->fp->count && fdmax <= 0))
356		msg->msg_flags |= MSG_CTRUNC;
357
358	/*
359	 * All of the files that fit in the message have had their usage counts
360	 * incremented, so we just free the list.
361	 */
362	__scm_destroy(scm);
363}
364EXPORT_SYMBOL(scm_detach_fds);
365
366struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
367{
368	struct scm_fp_list *new_fpl;
369	int i;
370
371	if (!fpl)
372		return NULL;
373
374	new_fpl = kmemdup(fpl, offsetof(struct scm_fp_list, fp[fpl->count]),
375			  GFP_KERNEL_ACCOUNT);
376	if (new_fpl) {
377		for (i = 0; i < fpl->count; i++)
378			get_file(fpl->fp[i]);
379		new_fpl->max = new_fpl->count;
380		new_fpl->user = get_uid(fpl->user);
381	}
382	return new_fpl;
383}
384EXPORT_SYMBOL(scm_fp_dup);