]>
Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* scm.c - Socket level control messages processing. |
2 | * | |
3 | * Author: Alexey Kuznetsov, <[email protected]> | |
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> | |
4fc268d2 | 14 | #include <linux/capability.h> |
1da177e4 LT |
15 | #include <linux/errno.h> |
16 | #include <linux/sched.h> | |
17 | #include <linux/mm.h> | |
18 | #include <linux/kernel.h> | |
1da177e4 LT |
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> | |
92f28d97 | 27 | #include <linux/pid_namespace.h> |
b488893a PE |
28 | #include <linux/pid.h> |
29 | #include <linux/nsproxy.h> | |
5a0e3ad6 | 30 | #include <linux/slab.h> |
1da177e4 | 31 | |
1da177e4 LT |
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> | |
d8429506 | 39 | #include <net/cls_cgroup.h> |
1da177e4 LT |
40 | |
41 | ||
42 | /* | |
4ec93edb | 43 | * Only allow a user to send credentials, that they could set with |
1da177e4 LT |
44 | * setu(g)id. |
45 | */ | |
46 | ||
47 | static __inline__ int scm_check_creds(struct ucred *creds) | |
48 | { | |
86a264ab | 49 | const struct cred *cred = current_cred(); |
b2e4f544 EB |
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; | |
b6dff3ec | 55 | |
92f28d97 | 56 | if ((creds->pid == task_tgid_vnr(current) || |
d661684c | 57 | ns_capable(task_active_pid_ns(current)->user_ns, CAP_SYS_ADMIN)) && |
b2e4f544 | 58 | ((uid_eq(uid, cred->uid) || uid_eq(uid, cred->euid) || |
c7b96acf | 59 | uid_eq(uid, cred->suid)) || ns_capable(cred->user_ns, CAP_SETUID)) && |
b2e4f544 | 60 | ((gid_eq(gid, cred->gid) || gid_eq(gid, cred->egid) || |
c7b96acf | 61 | gid_eq(gid, cred->sgid)) || ns_capable(cred->user_ns, CAP_SETGID))) { |
1da177e4 LT |
62 | return 0; |
63 | } | |
64 | return -EPERM; | |
65 | } | |
66 | ||
67 | static 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; | |
bba14de9 | 89 | fpl->max = SCM_MAX_FD; |
415e3d3e | 90 | fpl->user = NULL; |
1da177e4 LT |
91 | } |
92 | fpp = &fpl->fp[fpl->count]; | |
93 | ||
bba14de9 | 94 | if (fpl->count + num > fpl->max) |
1da177e4 | 95 | return -EINVAL; |
4ec93edb | 96 | |
1da177e4 LT |
97 | /* |
98 | * Verify the descriptors and increment the usage count. | |
99 | */ | |
4ec93edb | 100 | |
1da177e4 LT |
101 | for (i=0; i< num; i++) |
102 | { | |
103 | int fd = fdp[i]; | |
104 | struct file *file; | |
105 | ||
326be7b4 | 106 | if (fd < 0 || !(file = fget_raw(fd))) |
1da177e4 LT |
107 | return -EBADF; |
108 | *fpp++ = file; | |
109 | fpl->count++; | |
110 | } | |
415e3d3e HFS |
111 | |
112 | if (!fpl->user) | |
113 | fpl->user = get_uid(current_user()); | |
114 | ||
1da177e4 LT |
115 | return num; |
116 | } | |
117 | ||
118 | void __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; | |
6120d3db AV |
125 | for (i=fpl->count-1; i>=0; i--) |
126 | fput(fpl->fp[i]); | |
415e3d3e | 127 | free_uid(fpl->user); |
6120d3db | 128 | kfree(fpl); |
1da177e4 LT |
129 | } |
130 | } | |
9e34a5b5 | 131 | EXPORT_SYMBOL(__scm_destroy); |
1da177e4 LT |
132 | |
133 | int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p) | |
134 | { | |
135 | struct cmsghdr *cmsg; | |
136 | int err; | |
137 | ||
f95b414e | 138 | for_each_cmsghdr(cmsg, msg) { |
1da177e4 LT |
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. | |
4ec93edb | 145 | But if cmsg_level is not SOL_SOCKET, we do not check |
1da177e4 LT |
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: | |
76dadd76 EB |
158 | if (!sock->ops || sock->ops->family != PF_UNIX) |
159 | goto error; | |
1da177e4 LT |
160 | err=scm_fp_copy(cmsg, &p->fp); |
161 | if (err<0) | |
162 | goto error; | |
163 | break; | |
164 | case SCM_CREDENTIALS: | |
b2e4f544 | 165 | { |
dbe9a417 | 166 | struct ucred creds; |
b2e4f544 EB |
167 | kuid_t uid; |
168 | kgid_t gid; | |
1da177e4 LT |
169 | if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred))) |
170 | goto error; | |
dbe9a417 EB |
171 | memcpy(&creds, CMSG_DATA(cmsg), sizeof(struct ucred)); |
172 | err = scm_check_creds(&creds); | |
1da177e4 LT |
173 | if (err) |
174 | goto error; | |
257b5358 | 175 | |
dbe9a417 EB |
176 | p->creds.pid = creds.pid; |
177 | if (!p->pid || pid_vnr(p->pid) != creds.pid) { | |
257b5358 EB |
178 | struct pid *pid; |
179 | err = -ESRCH; | |
dbe9a417 | 180 | pid = find_get_pid(creds.pid); |
257b5358 EB |
181 | if (!pid) |
182 | goto error; | |
183 | put_pid(p->pid); | |
184 | p->pid = pid; | |
185 | } | |
186 | ||
b2e4f544 | 187 | err = -EINVAL; |
dbe9a417 EB |
188 | uid = make_kuid(current_user_ns(), creds.uid); |
189 | gid = make_kgid(current_user_ns(), creds.gid); | |
b2e4f544 EB |
190 | if (!uid_valid(uid) || !gid_valid(gid)) |
191 | goto error; | |
192 | ||
dbe9a417 EB |
193 | p->creds.uid = uid; |
194 | p->creds.gid = gid; | |
1da177e4 | 195 | break; |
b2e4f544 | 196 | } |
1da177e4 LT |
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; | |
4ec93edb | 208 | |
1da177e4 LT |
209 | error: |
210 | scm_destroy(p); | |
211 | return err; | |
212 | } | |
9e34a5b5 | 213 | EXPORT_SYMBOL(__scm_send); |
1da177e4 LT |
214 | |
215 | int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data) | |
216 | { | |
cfcabdcc SH |
217 | struct cmsghdr __user *cm |
218 | = (__force struct cmsghdr __user *)msg->msg_control; | |
1da177e4 LT |
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)) | |
4ec93edb | 240 | goto out; |
1da177e4 LT |
241 | if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr))) |
242 | goto out; | |
243 | cmlen = CMSG_SPACE(len); | |
1ac70e7a WY |
244 | if (msg->msg_controllen < cmlen) |
245 | cmlen = msg->msg_controllen; | |
1da177e4 LT |
246 | msg->msg_control += cmlen; |
247 | msg->msg_controllen -= cmlen; | |
248 | err = 0; | |
249 | out: | |
250 | return err; | |
251 | } | |
9e34a5b5 | 252 | EXPORT_SYMBOL(put_cmsg); |
1da177e4 LT |
253 | |
254 | void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm) | |
255 | { | |
cfcabdcc SH |
256 | struct cmsghdr __user *cm |
257 | = (__force struct cmsghdr __user*)msg->msg_control; | |
1da177e4 LT |
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 | ||
cfcabdcc SH |
277 | for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax; |
278 | i++, cmfptr++) | |
1da177e4 | 279 | { |
48a87cc2 | 280 | struct socket *sock; |
1da177e4 LT |
281 | int new_fd; |
282 | err = security_file_receive(fp[i]); | |
283 | if (err) | |
284 | break; | |
4a19542e UD |
285 | err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & msg->msg_flags |
286 | ? O_CLOEXEC : 0); | |
1da177e4 LT |
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. */ | |
48a87cc2 | 296 | sock = sock_from_file(fp[i], &err); |
d8429506 | 297 | if (sock) { |
2a56a1fe TH |
298 | sock_update_netprioidx(&sock->sk->sk_cgrp_data); |
299 | sock_update_classid(&sock->sk->sk_cgrp_data); | |
d8429506 | 300 | } |
cb0942b8 | 301 | fd_install(new_fd, get_file(fp[i])); |
1da177e4 LT |
302 | } |
303 | ||
304 | if (i > 0) | |
305 | { | |
306 | int cmlen = CMSG_LEN(i*sizeof(int)); | |
effee6a0 | 307 | err = put_user(SOL_SOCKET, &cm->cmsg_level); |
1da177e4 LT |
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)); | |
6900317f DB |
314 | if (msg->msg_controllen < cmlen) |
315 | cmlen = msg->msg_controllen; | |
1da177e4 LT |
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 | } | |
9e34a5b5 | 329 | EXPORT_SYMBOL(scm_detach_fds); |
1da177e4 LT |
330 | |
331 | struct 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 | ||
bba14de9 ED |
339 | new_fpl = kmemdup(fpl, offsetof(struct scm_fp_list, fp[fpl->count]), |
340 | GFP_KERNEL); | |
1da177e4 | 341 | if (new_fpl) { |
bba14de9 | 342 | for (i = 0; i < fpl->count; i++) |
1da177e4 | 343 | get_file(fpl->fp[i]); |
bba14de9 | 344 | new_fpl->max = new_fpl->count; |
415e3d3e | 345 | new_fpl->user = get_uid(fpl->user); |
1da177e4 LT |
346 | } |
347 | return new_fpl; | |
348 | } | |
1da177e4 | 349 | EXPORT_SYMBOL(scm_fp_dup); |