Loading...
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 fpl->user = NULL;
91 }
92 fpp = &fpl->fp[fpl->count];
93
94 if (fpl->count + num > fpl->max)
95 return -EINVAL;
96
97 /*
98 * Verify the descriptors and increment the usage count.
99 */
100
101 for (i=0; i< num; i++)
102 {
103 int fd = fdp[i];
104 struct file *file;
105
106 if (fd < 0 || !(file = fget_raw(fd)))
107 return -EBADF;
108 *fpp++ = file;
109 fpl->count++;
110 }
111
112 if (!fpl->user)
113 fpl->user = get_uid(current_user());
114
115 return num;
116}
117
118void __scm_destroy(struct scm_cookie *scm)
119{
120 struct scm_fp_list *fpl = scm->fp;
121 int i;
122
123 if (fpl) {
124 scm->fp = NULL;
125 for (i=fpl->count-1; i>=0; i--)
126 fput(fpl->fp[i]);
127 free_uid(fpl->user);
128 kfree(fpl);
129 }
130}
131EXPORT_SYMBOL(__scm_destroy);
132
133int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
134{
135 struct cmsghdr *cmsg;
136 int err;
137
138 for_each_cmsghdr(cmsg, msg) {
139 err = -EINVAL;
140
141 /* Verify that cmsg_len is at least sizeof(struct cmsghdr) */
142 /* The first check was omitted in <= 2.2.5. The reasoning was
143 that parser checks cmsg_len in any case, so that
144 additional check would be work duplication.
145 But if cmsg_level is not SOL_SOCKET, we do not check
146 for too short ancillary data object at all! Oops.
147 OK, let's add it...
148 */
149 if (!CMSG_OK(msg, cmsg))
150 goto error;
151
152 if (cmsg->cmsg_level != SOL_SOCKET)
153 continue;
154
155 switch (cmsg->cmsg_type)
156 {
157 case SCM_RIGHTS:
158 if (!sock->ops || sock->ops->family != PF_UNIX)
159 goto error;
160 err=scm_fp_copy(cmsg, &p->fp);
161 if (err<0)
162 goto error;
163 break;
164 case SCM_CREDENTIALS:
165 {
166 struct ucred creds;
167 kuid_t uid;
168 kgid_t gid;
169 if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
170 goto error;
171 memcpy(&creds, CMSG_DATA(cmsg), sizeof(struct ucred));
172 err = scm_check_creds(&creds);
173 if (err)
174 goto error;
175
176 p->creds.pid = creds.pid;
177 if (!p->pid || pid_vnr(p->pid) != creds.pid) {
178 struct pid *pid;
179 err = -ESRCH;
180 pid = find_get_pid(creds.pid);
181 if (!pid)
182 goto error;
183 put_pid(p->pid);
184 p->pid = pid;
185 }
186
187 err = -EINVAL;
188 uid = make_kuid(current_user_ns(), creds.uid);
189 gid = make_kgid(current_user_ns(), creds.gid);
190 if (!uid_valid(uid) || !gid_valid(gid))
191 goto error;
192
193 p->creds.uid = uid;
194 p->creds.gid = gid;
195 break;
196 }
197 default:
198 goto error;
199 }
200 }
201
202 if (p->fp && !p->fp->count)
203 {
204 kfree(p->fp);
205 p->fp = NULL;
206 }
207 return 0;
208
209error:
210 scm_destroy(p);
211 return err;
212}
213EXPORT_SYMBOL(__scm_send);
214
215int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
216{
217 struct cmsghdr __user *cm
218 = (__force struct cmsghdr __user *)msg->msg_control;
219 struct cmsghdr cmhdr;
220 int cmlen = CMSG_LEN(len);
221 int err;
222
223 if (MSG_CMSG_COMPAT & msg->msg_flags)
224 return put_cmsg_compat(msg, level, type, len, data);
225
226 if (cm==NULL || msg->msg_controllen < sizeof(*cm)) {
227 msg->msg_flags |= MSG_CTRUNC;
228 return 0; /* XXX: return error? check spec. */
229 }
230 if (msg->msg_controllen < cmlen) {
231 msg->msg_flags |= MSG_CTRUNC;
232 cmlen = msg->msg_controllen;
233 }
234 cmhdr.cmsg_level = level;
235 cmhdr.cmsg_type = type;
236 cmhdr.cmsg_len = cmlen;
237
238 err = -EFAULT;
239 if (copy_to_user(cm, &cmhdr, sizeof cmhdr))
240 goto out;
241 if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr)))
242 goto out;
243 cmlen = CMSG_SPACE(len);
244 if (msg->msg_controllen < cmlen)
245 cmlen = msg->msg_controllen;
246 msg->msg_control += cmlen;
247 msg->msg_controllen -= cmlen;
248 err = 0;
249out:
250 return err;
251}
252EXPORT_SYMBOL(put_cmsg);
253
254void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
255{
256 struct cmsghdr __user *cm
257 = (__force struct cmsghdr __user*)msg->msg_control;
258
259 int fdmax = 0;
260 int fdnum = scm->fp->count;
261 struct file **fp = scm->fp->fp;
262 int __user *cmfptr;
263 int err = 0, i;
264
265 if (MSG_CMSG_COMPAT & msg->msg_flags) {
266 scm_detach_fds_compat(msg, scm);
267 return;
268 }
269
270 if (msg->msg_controllen > sizeof(struct cmsghdr))
271 fdmax = ((msg->msg_controllen - sizeof(struct cmsghdr))
272 / sizeof(int));
273
274 if (fdnum < fdmax)
275 fdmax = fdnum;
276
277 for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax;
278 i++, cmfptr++)
279 {
280 struct socket *sock;
281 int new_fd;
282 err = security_file_receive(fp[i]);
283 if (err)
284 break;
285 err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & msg->msg_flags
286 ? O_CLOEXEC : 0);
287 if (err < 0)
288 break;
289 new_fd = err;
290 err = put_user(new_fd, cmfptr);
291 if (err) {
292 put_unused_fd(new_fd);
293 break;
294 }
295 /* Bump the usage count and install the file. */
296 sock = sock_from_file(fp[i], &err);
297 if (sock) {
298 sock_update_netprioidx(&sock->sk->sk_cgrp_data);
299 sock_update_classid(&sock->sk->sk_cgrp_data);
300 }
301 fd_install(new_fd, get_file(fp[i]));
302 }
303
304 if (i > 0)
305 {
306 int cmlen = CMSG_LEN(i*sizeof(int));
307 err = put_user(SOL_SOCKET, &cm->cmsg_level);
308 if (!err)
309 err = put_user(SCM_RIGHTS, &cm->cmsg_type);
310 if (!err)
311 err = put_user(cmlen, &cm->cmsg_len);
312 if (!err) {
313 cmlen = CMSG_SPACE(i*sizeof(int));
314 if (msg->msg_controllen < cmlen)
315 cmlen = msg->msg_controllen;
316 msg->msg_control += cmlen;
317 msg->msg_controllen -= cmlen;
318 }
319 }
320 if (i < fdnum || (fdnum && fdmax <= 0))
321 msg->msg_flags |= MSG_CTRUNC;
322
323 /*
324 * All of the files that fit in the message have had their
325 * usage counts incremented, so we just free the list.
326 */
327 __scm_destroy(scm);
328}
329EXPORT_SYMBOL(scm_detach_fds);
330
331struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
332{
333 struct scm_fp_list *new_fpl;
334 int i;
335
336 if (!fpl)
337 return NULL;
338
339 new_fpl = kmemdup(fpl, offsetof(struct scm_fp_list, fp[fpl->count]),
340 GFP_KERNEL);
341 if (new_fpl) {
342 for (i = 0; i < fpl->count; i++)
343 get_file(fpl->fp[i]);
344 new_fpl->max = new_fpl->count;
345 new_fpl->user = get_uid(fpl->user);
346 }
347 return new_fpl;
348}
349EXPORT_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/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);