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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_namespace.h>
28#include <linux/pid.h>
29#include <linux/nsproxy.h>
30#include <linux/slab.h>
31
32#include <asm/uaccess.h>
33
34#include <net/protocol.h>
35#include <linux/skbuff.h>
36#include <net/sock.h>
37#include <net/compat.h>
38#include <net/scm.h>
39#include <net/cls_cgroup.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 - CMSG_ALIGN(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);
85 if (!fpl)
86 return -ENOMEM;
87 *fplp = fpl;
88 fpl->count = 0;
89 fpl->max = SCM_MAX_FD;
90 }
91 fpp = &fpl->fp[fpl->count];
92
93 if (fpl->count + num > fpl->max)
94 return -EINVAL;
95
96 /*
97 * Verify the descriptors and increment the usage count.
98 */
99
100 for (i=0; i< num; i++)
101 {
102 int fd = fdp[i];
103 struct file *file;
104
105 if (fd < 0 || !(file = fget_raw(fd)))
106 return -EBADF;
107 *fpp++ = file;
108 fpl->count++;
109 }
110 return num;
111}
112
113void __scm_destroy(struct scm_cookie *scm)
114{
115 struct scm_fp_list *fpl = scm->fp;
116 int i;
117
118 if (fpl) {
119 scm->fp = NULL;
120 for (i=fpl->count-1; i>=0; i--)
121 fput(fpl->fp[i]);
122 kfree(fpl);
123 }
124}
125EXPORT_SYMBOL(__scm_destroy);
126
127int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
128{
129 struct cmsghdr *cmsg;
130 int err;
131
132 for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg))
133 {
134 err = -EINVAL;
135
136 /* Verify that cmsg_len is at least sizeof(struct cmsghdr) */
137 /* The first check was omitted in <= 2.2.5. The reasoning was
138 that parser checks cmsg_len in any case, so that
139 additional check would be work duplication.
140 But if cmsg_level is not SOL_SOCKET, we do not check
141 for too short ancillary data object at all! Oops.
142 OK, let's add it...
143 */
144 if (!CMSG_OK(msg, cmsg))
145 goto error;
146
147 if (cmsg->cmsg_level != SOL_SOCKET)
148 continue;
149
150 switch (cmsg->cmsg_type)
151 {
152 case SCM_RIGHTS:
153 if (!sock->ops || sock->ops->family != PF_UNIX)
154 goto error;
155 err=scm_fp_copy(cmsg, &p->fp);
156 if (err<0)
157 goto error;
158 break;
159 case SCM_CREDENTIALS:
160 {
161 struct ucred creds;
162 kuid_t uid;
163 kgid_t gid;
164 if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
165 goto error;
166 memcpy(&creds, CMSG_DATA(cmsg), sizeof(struct ucred));
167 err = scm_check_creds(&creds);
168 if (err)
169 goto error;
170
171 p->creds.pid = creds.pid;
172 if (!p->pid || pid_vnr(p->pid) != creds.pid) {
173 struct pid *pid;
174 err = -ESRCH;
175 pid = find_get_pid(creds.pid);
176 if (!pid)
177 goto error;
178 put_pid(p->pid);
179 p->pid = pid;
180 }
181
182 err = -EINVAL;
183 uid = make_kuid(current_user_ns(), creds.uid);
184 gid = make_kgid(current_user_ns(), creds.gid);
185 if (!uid_valid(uid) || !gid_valid(gid))
186 goto error;
187
188 p->creds.uid = uid;
189 p->creds.gid = gid;
190 break;
191 }
192 default:
193 goto error;
194 }
195 }
196
197 if (p->fp && !p->fp->count)
198 {
199 kfree(p->fp);
200 p->fp = NULL;
201 }
202 return 0;
203
204error:
205 scm_destroy(p);
206 return err;
207}
208EXPORT_SYMBOL(__scm_send);
209
210int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
211{
212 struct cmsghdr __user *cm
213 = (__force struct cmsghdr __user *)msg->msg_control;
214 struct cmsghdr cmhdr;
215 int cmlen = CMSG_LEN(len);
216 int err;
217
218 if (MSG_CMSG_COMPAT & msg->msg_flags)
219 return put_cmsg_compat(msg, level, type, len, data);
220
221 if (cm==NULL || msg->msg_controllen < sizeof(*cm)) {
222 msg->msg_flags |= MSG_CTRUNC;
223 return 0; /* XXX: return error? check spec. */
224 }
225 if (msg->msg_controllen < cmlen) {
226 msg->msg_flags |= MSG_CTRUNC;
227 cmlen = msg->msg_controllen;
228 }
229 cmhdr.cmsg_level = level;
230 cmhdr.cmsg_type = type;
231 cmhdr.cmsg_len = cmlen;
232
233 err = -EFAULT;
234 if (copy_to_user(cm, &cmhdr, sizeof cmhdr))
235 goto out;
236 if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr)))
237 goto out;
238 cmlen = CMSG_SPACE(len);
239 if (msg->msg_controllen < cmlen)
240 cmlen = msg->msg_controllen;
241 msg->msg_control += cmlen;
242 msg->msg_controllen -= cmlen;
243 err = 0;
244out:
245 return err;
246}
247EXPORT_SYMBOL(put_cmsg);
248
249void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
250{
251 struct cmsghdr __user *cm
252 = (__force struct cmsghdr __user*)msg->msg_control;
253
254 int fdmax = 0;
255 int fdnum = scm->fp->count;
256 struct file **fp = scm->fp->fp;
257 int __user *cmfptr;
258 int err = 0, i;
259
260 if (MSG_CMSG_COMPAT & msg->msg_flags) {
261 scm_detach_fds_compat(msg, scm);
262 return;
263 }
264
265 if (msg->msg_controllen > sizeof(struct cmsghdr))
266 fdmax = ((msg->msg_controllen - sizeof(struct cmsghdr))
267 / sizeof(int));
268
269 if (fdnum < fdmax)
270 fdmax = fdnum;
271
272 for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax;
273 i++, cmfptr++)
274 {
275 struct socket *sock;
276 int new_fd;
277 err = security_file_receive(fp[i]);
278 if (err)
279 break;
280 err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & msg->msg_flags
281 ? O_CLOEXEC : 0);
282 if (err < 0)
283 break;
284 new_fd = err;
285 err = put_user(new_fd, cmfptr);
286 if (err) {
287 put_unused_fd(new_fd);
288 break;
289 }
290 /* Bump the usage count and install the file. */
291 sock = sock_from_file(fp[i], &err);
292 if (sock) {
293 sock_update_netprioidx(sock->sk);
294 sock_update_classid(sock->sk);
295 }
296 fd_install(new_fd, get_file(fp[i]));
297 }
298
299 if (i > 0)
300 {
301 int cmlen = CMSG_LEN(i*sizeof(int));
302 err = put_user(SOL_SOCKET, &cm->cmsg_level);
303 if (!err)
304 err = put_user(SCM_RIGHTS, &cm->cmsg_type);
305 if (!err)
306 err = put_user(cmlen, &cm->cmsg_len);
307 if (!err) {
308 cmlen = CMSG_SPACE(i*sizeof(int));
309 msg->msg_control += cmlen;
310 msg->msg_controllen -= cmlen;
311 }
312 }
313 if (i < fdnum || (fdnum && fdmax <= 0))
314 msg->msg_flags |= MSG_CTRUNC;
315
316 /*
317 * All of the files that fit in the message have had their
318 * usage counts incremented, so we just free the list.
319 */
320 __scm_destroy(scm);
321}
322EXPORT_SYMBOL(scm_detach_fds);
323
324struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
325{
326 struct scm_fp_list *new_fpl;
327 int i;
328
329 if (!fpl)
330 return NULL;
331
332 new_fpl = kmemdup(fpl, offsetof(struct scm_fp_list, fp[fpl->count]),
333 GFP_KERNEL);
334 if (new_fpl) {
335 for (i = 0; i < fpl->count; i++)
336 get_file(fpl->fp[i]);
337 new_fpl->max = new_fpl->count;
338 }
339 return new_fpl;
340}
341EXPORT_SYMBOL(scm_fp_dup);
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);