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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#if IS_ENABLED(CONFIG_UNIX)
93 fpl->inflight = false;
94 fpl->dead = false;
95 fpl->edges = NULL;
96 INIT_LIST_HEAD(&fpl->vertices);
97#endif
98 }
99 fpp = &fpl->fp[fpl->count];
100
101 if (fpl->count + num > fpl->max)
102 return -EINVAL;
103
104 /*
105 * Verify the descriptors and increment the usage count.
106 */
107
108 for (i=0; i< num; i++)
109 {
110 int fd = fdp[i];
111 struct file *file;
112
113 if (fd < 0 || !(file = fget_raw(fd)))
114 return -EBADF;
115 /* don't allow io_uring files */
116 if (io_is_uring_fops(file)) {
117 fput(file);
118 return -EINVAL;
119 }
120 if (unix_get_socket(file))
121 fpl->count_unix++;
122
123 *fpp++ = file;
124 fpl->count++;
125 }
126
127 if (!fpl->user)
128 fpl->user = get_uid(current_user());
129
130 return num;
131}
132
133void __scm_destroy(struct scm_cookie *scm)
134{
135 struct scm_fp_list *fpl = scm->fp;
136 int i;
137
138 if (fpl) {
139 scm->fp = NULL;
140 for (i=fpl->count-1; i>=0; i--)
141 fput(fpl->fp[i]);
142 free_uid(fpl->user);
143 kfree(fpl);
144 }
145}
146EXPORT_SYMBOL(__scm_destroy);
147
148int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
149{
150 const struct proto_ops *ops = READ_ONCE(sock->ops);
151 struct cmsghdr *cmsg;
152 int err;
153
154 for_each_cmsghdr(cmsg, msg) {
155 err = -EINVAL;
156
157 /* Verify that cmsg_len is at least sizeof(struct cmsghdr) */
158 /* The first check was omitted in <= 2.2.5. The reasoning was
159 that parser checks cmsg_len in any case, so that
160 additional check would be work duplication.
161 But if cmsg_level is not SOL_SOCKET, we do not check
162 for too short ancillary data object at all! Oops.
163 OK, let's add it...
164 */
165 if (!CMSG_OK(msg, cmsg))
166 goto error;
167
168 if (cmsg->cmsg_level != SOL_SOCKET)
169 continue;
170
171 switch (cmsg->cmsg_type)
172 {
173 case SCM_RIGHTS:
174 if (!ops || ops->family != PF_UNIX)
175 goto error;
176 err=scm_fp_copy(cmsg, &p->fp);
177 if (err<0)
178 goto error;
179 break;
180 case SCM_CREDENTIALS:
181 {
182 struct ucred creds;
183 kuid_t uid;
184 kgid_t gid;
185 if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
186 goto error;
187 memcpy(&creds, CMSG_DATA(cmsg), sizeof(struct ucred));
188 err = scm_check_creds(&creds);
189 if (err)
190 goto error;
191
192 p->creds.pid = creds.pid;
193 if (!p->pid || pid_vnr(p->pid) != creds.pid) {
194 struct pid *pid;
195 err = -ESRCH;
196 pid = find_get_pid(creds.pid);
197 if (!pid)
198 goto error;
199 put_pid(p->pid);
200 p->pid = pid;
201 }
202
203 err = -EINVAL;
204 uid = make_kuid(current_user_ns(), creds.uid);
205 gid = make_kgid(current_user_ns(), creds.gid);
206 if (!uid_valid(uid) || !gid_valid(gid))
207 goto error;
208
209 p->creds.uid = uid;
210 p->creds.gid = gid;
211 break;
212 }
213 default:
214 goto error;
215 }
216 }
217
218 if (p->fp && !p->fp->count)
219 {
220 kfree(p->fp);
221 p->fp = NULL;
222 }
223 return 0;
224
225error:
226 scm_destroy(p);
227 return err;
228}
229EXPORT_SYMBOL(__scm_send);
230
231int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
232{
233 int cmlen = CMSG_LEN(len);
234
235 if (msg->msg_flags & MSG_CMSG_COMPAT)
236 return put_cmsg_compat(msg, level, type, len, data);
237
238 if (!msg->msg_control || msg->msg_controllen < sizeof(struct cmsghdr)) {
239 msg->msg_flags |= MSG_CTRUNC;
240 return 0; /* XXX: return error? check spec. */
241 }
242 if (msg->msg_controllen < cmlen) {
243 msg->msg_flags |= MSG_CTRUNC;
244 cmlen = msg->msg_controllen;
245 }
246
247 if (msg->msg_control_is_user) {
248 struct cmsghdr __user *cm = msg->msg_control_user;
249
250 check_object_size(data, cmlen - sizeof(*cm), true);
251
252 if (!user_write_access_begin(cm, cmlen))
253 goto efault;
254
255 unsafe_put_user(cmlen, &cm->cmsg_len, efault_end);
256 unsafe_put_user(level, &cm->cmsg_level, efault_end);
257 unsafe_put_user(type, &cm->cmsg_type, efault_end);
258 unsafe_copy_to_user(CMSG_USER_DATA(cm), data,
259 cmlen - sizeof(*cm), efault_end);
260 user_write_access_end();
261 } else {
262 struct cmsghdr *cm = msg->msg_control;
263
264 cm->cmsg_level = level;
265 cm->cmsg_type = type;
266 cm->cmsg_len = cmlen;
267 memcpy(CMSG_DATA(cm), data, cmlen - sizeof(*cm));
268 }
269
270 cmlen = min(CMSG_SPACE(len), msg->msg_controllen);
271 if (msg->msg_control_is_user)
272 msg->msg_control_user += cmlen;
273 else
274 msg->msg_control += cmlen;
275 msg->msg_controllen -= cmlen;
276 return 0;
277
278efault_end:
279 user_write_access_end();
280efault:
281 return -EFAULT;
282}
283EXPORT_SYMBOL(put_cmsg);
284
285int put_cmsg_notrunc(struct msghdr *msg, int level, int type, int len,
286 void *data)
287{
288 /* Don't produce truncated CMSGs */
289 if (!msg->msg_control || msg->msg_controllen < CMSG_LEN(len))
290 return -ETOOSMALL;
291
292 return put_cmsg(msg, level, type, len, data);
293}
294
295void put_cmsg_scm_timestamping64(struct msghdr *msg, struct scm_timestamping_internal *tss_internal)
296{
297 struct scm_timestamping64 tss;
298 int i;
299
300 for (i = 0; i < ARRAY_SIZE(tss.ts); i++) {
301 tss.ts[i].tv_sec = tss_internal->ts[i].tv_sec;
302 tss.ts[i].tv_nsec = tss_internal->ts[i].tv_nsec;
303 }
304
305 put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMPING_NEW, sizeof(tss), &tss);
306}
307EXPORT_SYMBOL(put_cmsg_scm_timestamping64);
308
309void put_cmsg_scm_timestamping(struct msghdr *msg, struct scm_timestamping_internal *tss_internal)
310{
311 struct scm_timestamping tss;
312 int i;
313
314 for (i = 0; i < ARRAY_SIZE(tss.ts); i++) {
315 tss.ts[i].tv_sec = tss_internal->ts[i].tv_sec;
316 tss.ts[i].tv_nsec = tss_internal->ts[i].tv_nsec;
317 }
318
319 put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMPING_OLD, sizeof(tss), &tss);
320}
321EXPORT_SYMBOL(put_cmsg_scm_timestamping);
322
323static int scm_max_fds(struct msghdr *msg)
324{
325 if (msg->msg_controllen <= sizeof(struct cmsghdr))
326 return 0;
327 return (msg->msg_controllen - sizeof(struct cmsghdr)) / sizeof(int);
328}
329
330void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
331{
332 struct cmsghdr __user *cm =
333 (__force struct cmsghdr __user *)msg->msg_control_user;
334 unsigned int o_flags = (msg->msg_flags & MSG_CMSG_CLOEXEC) ? O_CLOEXEC : 0;
335 int fdmax = min_t(int, scm_max_fds(msg), scm->fp->count);
336 int __user *cmsg_data = CMSG_USER_DATA(cm);
337 int err = 0, i;
338
339 /* no use for FD passing from kernel space callers */
340 if (WARN_ON_ONCE(!msg->msg_control_is_user))
341 return;
342
343 if (msg->msg_flags & MSG_CMSG_COMPAT) {
344 scm_detach_fds_compat(msg, scm);
345 return;
346 }
347
348 for (i = 0; i < fdmax; i++) {
349 err = scm_recv_one_fd(scm->fp->fp[i], cmsg_data + i, o_flags);
350 if (err < 0)
351 break;
352 }
353
354 if (i > 0) {
355 int cmlen = CMSG_LEN(i * sizeof(int));
356
357 err = put_user(SOL_SOCKET, &cm->cmsg_level);
358 if (!err)
359 err = put_user(SCM_RIGHTS, &cm->cmsg_type);
360 if (!err)
361 err = put_user(cmlen, &cm->cmsg_len);
362 if (!err) {
363 cmlen = CMSG_SPACE(i * sizeof(int));
364 if (msg->msg_controllen < cmlen)
365 cmlen = msg->msg_controllen;
366 msg->msg_control_user += cmlen;
367 msg->msg_controllen -= cmlen;
368 }
369 }
370
371 if (i < scm->fp->count || (scm->fp->count && fdmax <= 0))
372 msg->msg_flags |= MSG_CTRUNC;
373
374 /*
375 * All of the files that fit in the message have had their usage counts
376 * incremented, so we just free the list.
377 */
378 __scm_destroy(scm);
379}
380EXPORT_SYMBOL(scm_detach_fds);
381
382struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
383{
384 struct scm_fp_list *new_fpl;
385 int i;
386
387 if (!fpl)
388 return NULL;
389
390 new_fpl = kmemdup(fpl, offsetof(struct scm_fp_list, fp[fpl->count]),
391 GFP_KERNEL_ACCOUNT);
392 if (new_fpl) {
393 for (i = 0; i < fpl->count; i++)
394 get_file(fpl->fp[i]);
395
396 new_fpl->max = new_fpl->count;
397 new_fpl->user = get_uid(fpl->user);
398#if IS_ENABLED(CONFIG_UNIX)
399 new_fpl->inflight = false;
400 new_fpl->edges = NULL;
401 INIT_LIST_HEAD(&new_fpl->vertices);
402#endif
403 }
404 return new_fpl;
405}
406EXPORT_SYMBOL(scm_fp_dup);
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);