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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/system.h>
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
40
41/*
42 * Only allow a user to send credentials, that they could set with
43 * setu(g)id.
44 */
45
46static __inline__ int scm_check_creds(struct ucred *creds)
47{
48 const struct cred *cred = current_cred();
49
50 if ((creds->pid == task_tgid_vnr(current) || capable(CAP_SYS_ADMIN)) &&
51 ((creds->uid == cred->uid || creds->uid == cred->euid ||
52 creds->uid == cred->suid) || capable(CAP_SETUID)) &&
53 ((creds->gid == cred->gid || creds->gid == cred->egid ||
54 creds->gid == cred->sgid) || capable(CAP_SETGID))) {
55 return 0;
56 }
57 return -EPERM;
58}
59
60static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp)
61{
62 int *fdp = (int*)CMSG_DATA(cmsg);
63 struct scm_fp_list *fpl = *fplp;
64 struct file **fpp;
65 int i, num;
66
67 num = (cmsg->cmsg_len - CMSG_ALIGN(sizeof(struct cmsghdr)))/sizeof(int);
68
69 if (num <= 0)
70 return 0;
71
72 if (num > SCM_MAX_FD)
73 return -EINVAL;
74
75 if (!fpl)
76 {
77 fpl = kmalloc(sizeof(struct scm_fp_list), GFP_KERNEL);
78 if (!fpl)
79 return -ENOMEM;
80 *fplp = fpl;
81 fpl->count = 0;
82 fpl->max = SCM_MAX_FD;
83 }
84 fpp = &fpl->fp[fpl->count];
85
86 if (fpl->count + num > fpl->max)
87 return -EINVAL;
88
89 /*
90 * Verify the descriptors and increment the usage count.
91 */
92
93 for (i=0; i< num; i++)
94 {
95 int fd = fdp[i];
96 struct file *file;
97
98 if (fd < 0 || !(file = fget_raw(fd)))
99 return -EBADF;
100 *fpp++ = file;
101 fpl->count++;
102 }
103 return num;
104}
105
106void __scm_destroy(struct scm_cookie *scm)
107{
108 struct scm_fp_list *fpl = scm->fp;
109 int i;
110
111 if (fpl) {
112 scm->fp = NULL;
113 if (current->scm_work_list) {
114 list_add_tail(&fpl->list, current->scm_work_list);
115 } else {
116 LIST_HEAD(work_list);
117
118 current->scm_work_list = &work_list;
119
120 list_add(&fpl->list, &work_list);
121 while (!list_empty(&work_list)) {
122 fpl = list_first_entry(&work_list, struct scm_fp_list, list);
123
124 list_del(&fpl->list);
125 for (i=fpl->count-1; i>=0; i--)
126 fput(fpl->fp[i]);
127 kfree(fpl);
128 }
129
130 current->scm_work_list = NULL;
131 }
132 }
133}
134EXPORT_SYMBOL(__scm_destroy);
135
136int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
137{
138 struct cmsghdr *cmsg;
139 int err;
140
141 for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg))
142 {
143 err = -EINVAL;
144
145 /* Verify that cmsg_len is at least sizeof(struct cmsghdr) */
146 /* The first check was omitted in <= 2.2.5. The reasoning was
147 that parser checks cmsg_len in any case, so that
148 additional check would be work duplication.
149 But if cmsg_level is not SOL_SOCKET, we do not check
150 for too short ancillary data object at all! Oops.
151 OK, let's add it...
152 */
153 if (!CMSG_OK(msg, cmsg))
154 goto error;
155
156 if (cmsg->cmsg_level != SOL_SOCKET)
157 continue;
158
159 switch (cmsg->cmsg_type)
160 {
161 case SCM_RIGHTS:
162 if (!sock->ops || sock->ops->family != PF_UNIX)
163 goto error;
164 err=scm_fp_copy(cmsg, &p->fp);
165 if (err<0)
166 goto error;
167 break;
168 case SCM_CREDENTIALS:
169 if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
170 goto error;
171 memcpy(&p->creds, CMSG_DATA(cmsg), sizeof(struct ucred));
172 err = scm_check_creds(&p->creds);
173 if (err)
174 goto error;
175
176 if (pid_vnr(p->pid) != p->creds.pid) {
177 struct pid *pid;
178 err = -ESRCH;
179 pid = find_get_pid(p->creds.pid);
180 if (!pid)
181 goto error;
182 put_pid(p->pid);
183 p->pid = pid;
184 }
185
186 if ((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 put_cred(p->cred);
197 p->cred = cred;
198 }
199 break;
200 default:
201 goto error;
202 }
203 }
204
205 if (p->fp && !p->fp->count)
206 {
207 kfree(p->fp);
208 p->fp = NULL;
209 }
210 return 0;
211
212error:
213 scm_destroy(p);
214 return err;
215}
216EXPORT_SYMBOL(__scm_send);
217
218int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
219{
220 struct cmsghdr __user *cm
221 = (__force struct cmsghdr __user *)msg->msg_control;
222 struct cmsghdr cmhdr;
223 int cmlen = CMSG_LEN(len);
224 int err;
225
226 if (MSG_CMSG_COMPAT & msg->msg_flags)
227 return put_cmsg_compat(msg, level, type, len, data);
228
229 if (cm==NULL || msg->msg_controllen < sizeof(*cm)) {
230 msg->msg_flags |= MSG_CTRUNC;
231 return 0; /* XXX: return error? check spec. */
232 }
233 if (msg->msg_controllen < cmlen) {
234 msg->msg_flags |= MSG_CTRUNC;
235 cmlen = msg->msg_controllen;
236 }
237 cmhdr.cmsg_level = level;
238 cmhdr.cmsg_type = type;
239 cmhdr.cmsg_len = cmlen;
240
241 err = -EFAULT;
242 if (copy_to_user(cm, &cmhdr, sizeof cmhdr))
243 goto out;
244 if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr)))
245 goto out;
246 cmlen = CMSG_SPACE(len);
247 if (msg->msg_controllen < cmlen)
248 cmlen = msg->msg_controllen;
249 msg->msg_control += cmlen;
250 msg->msg_controllen -= cmlen;
251 err = 0;
252out:
253 return err;
254}
255EXPORT_SYMBOL(put_cmsg);
256
257void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
258{
259 struct cmsghdr __user *cm
260 = (__force struct cmsghdr __user*)msg->msg_control;
261
262 int fdmax = 0;
263 int fdnum = scm->fp->count;
264 struct file **fp = scm->fp->fp;
265 int __user *cmfptr;
266 int err = 0, i;
267
268 if (MSG_CMSG_COMPAT & msg->msg_flags) {
269 scm_detach_fds_compat(msg, scm);
270 return;
271 }
272
273 if (msg->msg_controllen > sizeof(struct cmsghdr))
274 fdmax = ((msg->msg_controllen - sizeof(struct cmsghdr))
275 / sizeof(int));
276
277 if (fdnum < fdmax)
278 fdmax = fdnum;
279
280 for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax;
281 i++, cmfptr++)
282 {
283 int new_fd;
284 err = security_file_receive(fp[i]);
285 if (err)
286 break;
287 err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & msg->msg_flags
288 ? O_CLOEXEC : 0);
289 if (err < 0)
290 break;
291 new_fd = err;
292 err = put_user(new_fd, cmfptr);
293 if (err) {
294 put_unused_fd(new_fd);
295 break;
296 }
297 /* Bump the usage count and install the file. */
298 get_file(fp[i]);
299 fd_install(new_fd, fp[i]);
300 }
301
302 if (i > 0)
303 {
304 int cmlen = CMSG_LEN(i*sizeof(int));
305 err = put_user(SOL_SOCKET, &cm->cmsg_level);
306 if (!err)
307 err = put_user(SCM_RIGHTS, &cm->cmsg_type);
308 if (!err)
309 err = put_user(cmlen, &cm->cmsg_len);
310 if (!err) {
311 cmlen = CMSG_SPACE(i*sizeof(int));
312 msg->msg_control += cmlen;
313 msg->msg_controllen -= cmlen;
314 }
315 }
316 if (i < fdnum || (fdnum && fdmax <= 0))
317 msg->msg_flags |= MSG_CTRUNC;
318
319 /*
320 * All of the files that fit in the message have had their
321 * usage counts incremented, so we just free the list.
322 */
323 __scm_destroy(scm);
324}
325EXPORT_SYMBOL(scm_detach_fds);
326
327struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
328{
329 struct scm_fp_list *new_fpl;
330 int i;
331
332 if (!fpl)
333 return NULL;
334
335 new_fpl = kmemdup(fpl, offsetof(struct scm_fp_list, fp[fpl->count]),
336 GFP_KERNEL);
337 if (new_fpl) {
338 for (i = 0; i < fpl->count; i++)
339 get_file(fpl->fp[i]);
340 new_fpl->max = new_fpl->count;
341 }
342 return new_fpl;
343}
344EXPORT_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);