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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/mm.h>
18#include <linux/kernel.h>
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>
27#include <linux/pid.h>
28#include <linux/nsproxy.h>
29#include <linux/slab.h>
30
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/*
41 * Only allow a user to send credentials, that they could set with
42 * setu(g)id.
43 */
44
45static __inline__ int scm_check_creds(struct ucred *creds)
46{
47 const struct cred *cred = current_cred();
48
49 if ((creds->pid == task_tgid_vnr(current) || capable(CAP_SYS_ADMIN)) &&
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))) {
54 return 0;
55 }
56 return -EPERM;
57}
58
59static 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;
80 fpl->count = 0;
81 fpl->max = SCM_MAX_FD;
82 }
83 fpp = &fpl->fp[fpl->count];
84
85 if (fpl->count + num > fpl->max)
86 return -EINVAL;
87
88 /*
89 * Verify the descriptors and increment the usage count.
90 */
91
92 for (i=0; i< num; i++)
93 {
94 int fd = fdp[i];
95 struct file *file;
96
97 if (fd < 0 || !(file = fget_raw(fd)))
98 return -EBADF;
99 *fpp++ = file;
100 fpl->count++;
101 }
102 return num;
103}
104
105void __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;
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 }
131 }
132}
133EXPORT_SYMBOL(__scm_destroy);
134
135int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
136{
137 struct cmsghdr *cmsg;
138 int err;
139
140 for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg))
141 {
142 err = -EINVAL;
143
144 /* Verify that cmsg_len is at least sizeof(struct cmsghdr) */
145 /* The first check was omitted in <= 2.2.5. The reasoning was
146 that parser checks cmsg_len in any case, so that
147 additional check would be work duplication.
148 But if cmsg_level is not SOL_SOCKET, we do not check
149 for too short ancillary data object at all! Oops.
150 OK, let's add it...
151 */
152 if (!CMSG_OK(msg, cmsg))
153 goto error;
154
155 if (cmsg->cmsg_level != SOL_SOCKET)
156 continue;
157
158 switch (cmsg->cmsg_type)
159 {
160 case SCM_RIGHTS:
161 if (!sock->ops || sock->ops->family != PF_UNIX)
162 goto error;
163 err=scm_fp_copy(cmsg, &p->fp);
164 if (err<0)
165 goto error;
166 break;
167 case SCM_CREDENTIALS:
168 if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
169 goto error;
170 memcpy(&p->creds, CMSG_DATA(cmsg), sizeof(struct ucred));
171 err = scm_check_creds(&p->creds);
172 if (err)
173 goto error;
174
175 if (!p->pid || pid_vnr(p->pid) != p->creds.pid) {
176 struct pid *pid;
177 err = -ESRCH;
178 pid = find_get_pid(p->creds.pid);
179 if (!pid)
180 goto error;
181 put_pid(p->pid);
182 p->pid = pid;
183 }
184
185 if (!p->cred ||
186 (p->cred->euid != p->creds.uid) ||
187 (p->cred->egid != p->creds.gid)) {
188 struct cred *cred;
189 err = -ENOMEM;
190 cred = prepare_creds();
191 if (!cred)
192 goto error;
193
194 cred->uid = cred->euid = p->creds.uid;
195 cred->gid = cred->egid = p->creds.gid;
196 if (p->cred)
197 put_cred(p->cred);
198 p->cred = cred;
199 }
200 break;
201 default:
202 goto error;
203 }
204 }
205
206 if (p->fp && !p->fp->count)
207 {
208 kfree(p->fp);
209 p->fp = NULL;
210 }
211 return 0;
212
213error:
214 scm_destroy(p);
215 return err;
216}
217EXPORT_SYMBOL(__scm_send);
218
219int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
220{
221 struct cmsghdr __user *cm
222 = (__force struct cmsghdr __user *)msg->msg_control;
223 struct cmsghdr cmhdr;
224 int cmlen = CMSG_LEN(len);
225 int err;
226
227 if (MSG_CMSG_COMPAT & msg->msg_flags)
228 return put_cmsg_compat(msg, level, type, len, data);
229
230 if (cm==NULL || msg->msg_controllen < sizeof(*cm)) {
231 msg->msg_flags |= MSG_CTRUNC;
232 return 0; /* XXX: return error? check spec. */
233 }
234 if (msg->msg_controllen < cmlen) {
235 msg->msg_flags |= MSG_CTRUNC;
236 cmlen = msg->msg_controllen;
237 }
238 cmhdr.cmsg_level = level;
239 cmhdr.cmsg_type = type;
240 cmhdr.cmsg_len = cmlen;
241
242 err = -EFAULT;
243 if (copy_to_user(cm, &cmhdr, sizeof cmhdr))
244 goto out;
245 if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr)))
246 goto out;
247 cmlen = CMSG_SPACE(len);
248 if (msg->msg_controllen < cmlen)
249 cmlen = msg->msg_controllen;
250 msg->msg_control += cmlen;
251 msg->msg_controllen -= cmlen;
252 err = 0;
253out:
254 return err;
255}
256EXPORT_SYMBOL(put_cmsg);
257
258void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
259{
260 struct cmsghdr __user *cm
261 = (__force struct cmsghdr __user*)msg->msg_control;
262
263 int fdmax = 0;
264 int fdnum = scm->fp->count;
265 struct file **fp = scm->fp->fp;
266 int __user *cmfptr;
267 int err = 0, i;
268
269 if (MSG_CMSG_COMPAT & msg->msg_flags) {
270 scm_detach_fds_compat(msg, scm);
271 return;
272 }
273
274 if (msg->msg_controllen > sizeof(struct cmsghdr))
275 fdmax = ((msg->msg_controllen - sizeof(struct cmsghdr))
276 / sizeof(int));
277
278 if (fdnum < fdmax)
279 fdmax = fdnum;
280
281 for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax;
282 i++, cmfptr++)
283 {
284 int new_fd;
285 err = security_file_receive(fp[i]);
286 if (err)
287 break;
288 err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & msg->msg_flags
289 ? O_CLOEXEC : 0);
290 if (err < 0)
291 break;
292 new_fd = err;
293 err = put_user(new_fd, cmfptr);
294 if (err) {
295 put_unused_fd(new_fd);
296 break;
297 }
298 /* Bump the usage count and install the file. */
299 get_file(fp[i]);
300 fd_install(new_fd, fp[i]);
301 }
302
303 if (i > 0)
304 {
305 int cmlen = CMSG_LEN(i*sizeof(int));
306 err = put_user(SOL_SOCKET, &cm->cmsg_level);
307 if (!err)
308 err = put_user(SCM_RIGHTS, &cm->cmsg_type);
309 if (!err)
310 err = put_user(cmlen, &cm->cmsg_len);
311 if (!err) {
312 cmlen = CMSG_SPACE(i*sizeof(int));
313 msg->msg_control += cmlen;
314 msg->msg_controllen -= cmlen;
315 }
316 }
317 if (i < fdnum || (fdnum && fdmax <= 0))
318 msg->msg_flags |= MSG_CTRUNC;
319
320 /*
321 * All of the files that fit in the message have had their
322 * usage counts incremented, so we just free the list.
323 */
324 __scm_destroy(scm);
325}
326EXPORT_SYMBOL(scm_detach_fds);
327
328struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
329{
330 struct scm_fp_list *new_fpl;
331 int i;
332
333 if (!fpl)
334 return NULL;
335
336 new_fpl = kmemdup(fpl, offsetof(struct scm_fp_list, fp[fpl->count]),
337 GFP_KERNEL);
338 if (new_fpl) {
339 for (i = 0; i < fpl->count; i++)
340 get_file(fpl->fp[i]);
341 new_fpl->max = new_fpl->count;
342 }
343 return new_fpl;
344}
345EXPORT_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
30#include <linux/uaccess.h>
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>
37#include <net/cls_cgroup.h>
38
39
40/*
41 * Only allow a user to send credentials, that they could set with
42 * setu(g)id.
43 */
44
45static __inline__ int scm_check_creds(struct ucred *creds)
46{
47 const struct cred *cred = current_cred();
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;
53
54 if ((creds->pid == task_tgid_vnr(current) ||
55 ns_capable(task_active_pid_ns(current)->user_ns, CAP_SYS_ADMIN)) &&
56 ((uid_eq(uid, cred->uid) || uid_eq(uid, cred->euid) ||
57 uid_eq(uid, cred->suid)) || ns_capable(cred->user_ns, CAP_SETUID)) &&
58 ((gid_eq(gid, cred->gid) || gid_eq(gid, cred->egid) ||
59 gid_eq(gid, cred->sgid)) || ns_capable(cred->user_ns, CAP_SETGID))) {
60 return 0;
61 }
62 return -EPERM;
63}
64
65static 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
72 num = (cmsg->cmsg_len - sizeof(struct cmsghdr))/sizeof(int);
73
74 if (num <= 0)
75 return 0;
76
77 if (num > SCM_MAX_FD)
78 return -EINVAL;
79
80 if (!fpl)
81 {
82 fpl = kmalloc(sizeof(struct scm_fp_list), GFP_KERNEL);
83 if (!fpl)
84 return -ENOMEM;
85 *fplp = fpl;
86 fpl->count = 0;
87 fpl->max = SCM_MAX_FD;
88 fpl->user = NULL;
89 }
90 fpp = &fpl->fp[fpl->count];
91
92 if (fpl->count + num > fpl->max)
93 return -EINVAL;
94
95 /*
96 * Verify the descriptors and increment the usage count.
97 */
98
99 for (i=0; i< num; i++)
100 {
101 int fd = fdp[i];
102 struct file *file;
103
104 if (fd < 0 || !(file = fget_raw(fd)))
105 return -EBADF;
106 *fpp++ = file;
107 fpl->count++;
108 }
109
110 if (!fpl->user)
111 fpl->user = get_uid(current_user());
112
113 return num;
114}
115
116void __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;
123 for (i=fpl->count-1; i>=0; i--)
124 fput(fpl->fp[i]);
125 free_uid(fpl->user);
126 kfree(fpl);
127 }
128}
129EXPORT_SYMBOL(__scm_destroy);
130
131int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
132{
133 struct cmsghdr *cmsg;
134 int err;
135
136 for_each_cmsghdr(cmsg, msg) {
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.
143 But if cmsg_level is not SOL_SOCKET, we do not check
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:
156 if (!sock->ops || sock->ops->family != PF_UNIX)
157 goto error;
158 err=scm_fp_copy(cmsg, &p->fp);
159 if (err<0)
160 goto error;
161 break;
162 case SCM_CREDENTIALS:
163 {
164 struct ucred creds;
165 kuid_t uid;
166 kgid_t gid;
167 if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
168 goto error;
169 memcpy(&creds, CMSG_DATA(cmsg), sizeof(struct ucred));
170 err = scm_check_creds(&creds);
171 if (err)
172 goto error;
173
174 p->creds.pid = creds.pid;
175 if (!p->pid || pid_vnr(p->pid) != creds.pid) {
176 struct pid *pid;
177 err = -ESRCH;
178 pid = find_get_pid(creds.pid);
179 if (!pid)
180 goto error;
181 put_pid(p->pid);
182 p->pid = pid;
183 }
184
185 err = -EINVAL;
186 uid = make_kuid(current_user_ns(), creds.uid);
187 gid = make_kgid(current_user_ns(), creds.gid);
188 if (!uid_valid(uid) || !gid_valid(gid))
189 goto error;
190
191 p->creds.uid = uid;
192 p->creds.gid = gid;
193 break;
194 }
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;
206
207error:
208 scm_destroy(p);
209 return err;
210}
211EXPORT_SYMBOL(__scm_send);
212
213int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
214{
215 struct cmsghdr __user *cm
216 = (__force struct cmsghdr __user *)msg->msg_control;
217 struct cmsghdr cmhdr;
218 int cmlen = CMSG_LEN(len);
219 int err;
220
221 if (MSG_CMSG_COMPAT & msg->msg_flags)
222 return put_cmsg_compat(msg, level, type, len, data);
223
224 if (cm==NULL || msg->msg_controllen < sizeof(*cm)) {
225 msg->msg_flags |= MSG_CTRUNC;
226 return 0; /* XXX: return error? check spec. */
227 }
228 if (msg->msg_controllen < cmlen) {
229 msg->msg_flags |= MSG_CTRUNC;
230 cmlen = msg->msg_controllen;
231 }
232 cmhdr.cmsg_level = level;
233 cmhdr.cmsg_type = type;
234 cmhdr.cmsg_len = cmlen;
235
236 err = -EFAULT;
237 if (copy_to_user(cm, &cmhdr, sizeof cmhdr))
238 goto out;
239 if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr)))
240 goto out;
241 cmlen = CMSG_SPACE(len);
242 if (msg->msg_controllen < cmlen)
243 cmlen = msg->msg_controllen;
244 msg->msg_control += cmlen;
245 msg->msg_controllen -= cmlen;
246 err = 0;
247out:
248 return err;
249}
250EXPORT_SYMBOL(put_cmsg);
251
252void put_cmsg_scm_timestamping64(struct msghdr *msg, struct scm_timestamping_internal *tss_internal)
253{
254 struct scm_timestamping64 tss;
255 int i;
256
257 for (i = 0; i < ARRAY_SIZE(tss.ts); i++) {
258 tss.ts[i].tv_sec = tss_internal->ts[i].tv_sec;
259 tss.ts[i].tv_nsec = tss_internal->ts[i].tv_nsec;
260 }
261
262 put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMPING_NEW, sizeof(tss), &tss);
263}
264EXPORT_SYMBOL(put_cmsg_scm_timestamping64);
265
266void put_cmsg_scm_timestamping(struct msghdr *msg, struct scm_timestamping_internal *tss_internal)
267{
268 struct scm_timestamping tss;
269 int i;
270
271 for (i = 0; i < ARRAY_SIZE(tss.ts); i++)
272 tss.ts[i] = timespec64_to_timespec(tss_internal->ts[i]);
273
274 put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMPING_OLD, sizeof(tss), &tss);
275}
276EXPORT_SYMBOL(put_cmsg_scm_timestamping);
277
278void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
279{
280 struct cmsghdr __user *cm
281 = (__force struct cmsghdr __user*)msg->msg_control;
282
283 int fdmax = 0;
284 int fdnum = scm->fp->count;
285 struct file **fp = scm->fp->fp;
286 int __user *cmfptr;
287 int err = 0, i;
288
289 if (MSG_CMSG_COMPAT & msg->msg_flags) {
290 scm_detach_fds_compat(msg, scm);
291 return;
292 }
293
294 if (msg->msg_controllen > sizeof(struct cmsghdr))
295 fdmax = ((msg->msg_controllen - sizeof(struct cmsghdr))
296 / sizeof(int));
297
298 if (fdnum < fdmax)
299 fdmax = fdnum;
300
301 for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax;
302 i++, cmfptr++)
303 {
304 struct socket *sock;
305 int new_fd;
306 err = security_file_receive(fp[i]);
307 if (err)
308 break;
309 err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & msg->msg_flags
310 ? O_CLOEXEC : 0);
311 if (err < 0)
312 break;
313 new_fd = err;
314 err = put_user(new_fd, cmfptr);
315 if (err) {
316 put_unused_fd(new_fd);
317 break;
318 }
319 /* Bump the usage count and install the file. */
320 sock = sock_from_file(fp[i], &err);
321 if (sock) {
322 sock_update_netprioidx(&sock->sk->sk_cgrp_data);
323 sock_update_classid(&sock->sk->sk_cgrp_data);
324 }
325 fd_install(new_fd, get_file(fp[i]));
326 }
327
328 if (i > 0)
329 {
330 int cmlen = CMSG_LEN(i*sizeof(int));
331 err = put_user(SOL_SOCKET, &cm->cmsg_level);
332 if (!err)
333 err = put_user(SCM_RIGHTS, &cm->cmsg_type);
334 if (!err)
335 err = put_user(cmlen, &cm->cmsg_len);
336 if (!err) {
337 cmlen = CMSG_SPACE(i*sizeof(int));
338 if (msg->msg_controllen < cmlen)
339 cmlen = msg->msg_controllen;
340 msg->msg_control += cmlen;
341 msg->msg_controllen -= cmlen;
342 }
343 }
344 if (i < fdnum || (fdnum && fdmax <= 0))
345 msg->msg_flags |= MSG_CTRUNC;
346
347 /*
348 * All of the files that fit in the message have had their
349 * usage counts incremented, so we just free the list.
350 */
351 __scm_destroy(scm);
352}
353EXPORT_SYMBOL(scm_detach_fds);
354
355struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
356{
357 struct scm_fp_list *new_fpl;
358 int i;
359
360 if (!fpl)
361 return NULL;
362
363 new_fpl = kmemdup(fpl, offsetof(struct scm_fp_list, fp[fpl->count]),
364 GFP_KERNEL);
365 if (new_fpl) {
366 for (i = 0; i < fpl->count; i++)
367 get_file(fpl->fp[i]);
368 new_fpl->max = new_fpl->count;
369 new_fpl->user = get_uid(fpl->user);
370 }
371 return new_fpl;
372}
373EXPORT_SYMBOL(scm_fp_dup);