Commit | Line | Data |
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1da177e4 LT |
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> | |
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; |
1da177e4 LT |
90 | } |
91 | fpp = &fpl->fp[fpl->count]; | |
92 | ||
bba14de9 | 93 | if (fpl->count + num > fpl->max) |
1da177e4 | 94 | return -EINVAL; |
4ec93edb | 95 | |
1da177e4 LT |
96 | /* |
97 | * Verify the descriptors and increment the usage count. | |
98 | */ | |
4ec93edb | 99 | |
1da177e4 LT |
100 | for (i=0; i< num; i++) |
101 | { | |
102 | int fd = fdp[i]; | |
103 | struct file *file; | |
104 | ||
326be7b4 | 105 | if (fd < 0 || !(file = fget_raw(fd))) |
1da177e4 LT |
106 | return -EBADF; |
107 | *fpp++ = file; | |
108 | fpl->count++; | |
109 | } | |
110 | return num; | |
111 | } | |
112 | ||
113 | void __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; | |
6120d3db AV |
120 | for (i=fpl->count-1; i>=0; i--) |
121 | fput(fpl->fp[i]); | |
122 | kfree(fpl); | |
1da177e4 LT |
123 | } |
124 | } | |
9e34a5b5 | 125 | EXPORT_SYMBOL(__scm_destroy); |
1da177e4 LT |
126 | |
127 | int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p) | |
128 | { | |
129 | struct cmsghdr *cmsg; | |
130 | int err; | |
131 | ||
f95b414e | 132 | for_each_cmsghdr(cmsg, msg) { |
1da177e4 LT |
133 | err = -EINVAL; |
134 | ||
135 | /* Verify that cmsg_len is at least sizeof(struct cmsghdr) */ | |
136 | /* The first check was omitted in <= 2.2.5. The reasoning was | |
137 | that parser checks cmsg_len in any case, so that | |
138 | additional check would be work duplication. | |
4ec93edb | 139 | But if cmsg_level is not SOL_SOCKET, we do not check |
1da177e4 LT |
140 | for too short ancillary data object at all! Oops. |
141 | OK, let's add it... | |
142 | */ | |
143 | if (!CMSG_OK(msg, cmsg)) | |
144 | goto error; | |
145 | ||
146 | if (cmsg->cmsg_level != SOL_SOCKET) | |
147 | continue; | |
148 | ||
149 | switch (cmsg->cmsg_type) | |
150 | { | |
151 | case SCM_RIGHTS: | |
76dadd76 EB |
152 | if (!sock->ops || sock->ops->family != PF_UNIX) |
153 | goto error; | |
1da177e4 LT |
154 | err=scm_fp_copy(cmsg, &p->fp); |
155 | if (err<0) | |
156 | goto error; | |
157 | break; | |
158 | case SCM_CREDENTIALS: | |
b2e4f544 | 159 | { |
dbe9a417 | 160 | struct ucred creds; |
b2e4f544 EB |
161 | kuid_t uid; |
162 | kgid_t gid; | |
1da177e4 LT |
163 | if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred))) |
164 | goto error; | |
dbe9a417 EB |
165 | memcpy(&creds, CMSG_DATA(cmsg), sizeof(struct ucred)); |
166 | err = scm_check_creds(&creds); | |
1da177e4 LT |
167 | if (err) |
168 | goto error; | |
257b5358 | 169 | |
dbe9a417 EB |
170 | p->creds.pid = creds.pid; |
171 | if (!p->pid || pid_vnr(p->pid) != creds.pid) { | |
257b5358 EB |
172 | struct pid *pid; |
173 | err = -ESRCH; | |
dbe9a417 | 174 | pid = find_get_pid(creds.pid); |
257b5358 EB |
175 | if (!pid) |
176 | goto error; | |
177 | put_pid(p->pid); | |
178 | p->pid = pid; | |
179 | } | |
180 | ||
b2e4f544 | 181 | err = -EINVAL; |
dbe9a417 EB |
182 | uid = make_kuid(current_user_ns(), creds.uid); |
183 | gid = make_kgid(current_user_ns(), creds.gid); | |
b2e4f544 EB |
184 | if (!uid_valid(uid) || !gid_valid(gid)) |
185 | goto error; | |
186 | ||
dbe9a417 EB |
187 | p->creds.uid = uid; |
188 | p->creds.gid = gid; | |
1da177e4 | 189 | break; |
b2e4f544 | 190 | } |
1da177e4 LT |
191 | default: |
192 | goto error; | |
193 | } | |
194 | } | |
195 | ||
196 | if (p->fp && !p->fp->count) | |
197 | { | |
198 | kfree(p->fp); | |
199 | p->fp = NULL; | |
200 | } | |
201 | return 0; | |
4ec93edb | 202 | |
1da177e4 LT |
203 | error: |
204 | scm_destroy(p); | |
205 | return err; | |
206 | } | |
9e34a5b5 | 207 | EXPORT_SYMBOL(__scm_send); |
1da177e4 LT |
208 | |
209 | int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data) | |
210 | { | |
cfcabdcc SH |
211 | struct cmsghdr __user *cm |
212 | = (__force struct cmsghdr __user *)msg->msg_control; | |
1da177e4 LT |
213 | struct cmsghdr cmhdr; |
214 | int cmlen = CMSG_LEN(len); | |
215 | int err; | |
216 | ||
217 | if (MSG_CMSG_COMPAT & msg->msg_flags) | |
218 | return put_cmsg_compat(msg, level, type, len, data); | |
219 | ||
220 | if (cm==NULL || msg->msg_controllen < sizeof(*cm)) { | |
221 | msg->msg_flags |= MSG_CTRUNC; | |
222 | return 0; /* XXX: return error? check spec. */ | |
223 | } | |
224 | if (msg->msg_controllen < cmlen) { | |
225 | msg->msg_flags |= MSG_CTRUNC; | |
226 | cmlen = msg->msg_controllen; | |
227 | } | |
228 | cmhdr.cmsg_level = level; | |
229 | cmhdr.cmsg_type = type; | |
230 | cmhdr.cmsg_len = cmlen; | |
231 | ||
232 | err = -EFAULT; | |
233 | if (copy_to_user(cm, &cmhdr, sizeof cmhdr)) | |
4ec93edb | 234 | goto out; |
1da177e4 LT |
235 | if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr))) |
236 | goto out; | |
237 | cmlen = CMSG_SPACE(len); | |
1ac70e7a WY |
238 | if (msg->msg_controllen < cmlen) |
239 | cmlen = msg->msg_controllen; | |
1da177e4 LT |
240 | msg->msg_control += cmlen; |
241 | msg->msg_controllen -= cmlen; | |
242 | err = 0; | |
243 | out: | |
244 | return err; | |
245 | } | |
9e34a5b5 | 246 | EXPORT_SYMBOL(put_cmsg); |
1da177e4 LT |
247 | |
248 | void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm) | |
249 | { | |
cfcabdcc SH |
250 | struct cmsghdr __user *cm |
251 | = (__force struct cmsghdr __user*)msg->msg_control; | |
1da177e4 LT |
252 | |
253 | int fdmax = 0; | |
254 | int fdnum = scm->fp->count; | |
255 | struct file **fp = scm->fp->fp; | |
256 | int __user *cmfptr; | |
257 | int err = 0, i; | |
258 | ||
259 | if (MSG_CMSG_COMPAT & msg->msg_flags) { | |
260 | scm_detach_fds_compat(msg, scm); | |
261 | return; | |
262 | } | |
263 | ||
264 | if (msg->msg_controllen > sizeof(struct cmsghdr)) | |
265 | fdmax = ((msg->msg_controllen - sizeof(struct cmsghdr)) | |
266 | / sizeof(int)); | |
267 | ||
268 | if (fdnum < fdmax) | |
269 | fdmax = fdnum; | |
270 | ||
cfcabdcc SH |
271 | for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax; |
272 | i++, cmfptr++) | |
1da177e4 | 273 | { |
48a87cc2 | 274 | struct socket *sock; |
1da177e4 LT |
275 | int new_fd; |
276 | err = security_file_receive(fp[i]); | |
277 | if (err) | |
278 | break; | |
4a19542e UD |
279 | err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & msg->msg_flags |
280 | ? O_CLOEXEC : 0); | |
1da177e4 LT |
281 | if (err < 0) |
282 | break; | |
283 | new_fd = err; | |
284 | err = put_user(new_fd, cmfptr); | |
285 | if (err) { | |
286 | put_unused_fd(new_fd); | |
287 | break; | |
288 | } | |
289 | /* Bump the usage count and install the file. */ | |
48a87cc2 | 290 | sock = sock_from_file(fp[i], &err); |
d8429506 | 291 | if (sock) { |
6ffd4641 | 292 | sock_update_netprioidx(sock->sk); |
211d2f97 | 293 | sock_update_classid(sock->sk); |
d8429506 | 294 | } |
cb0942b8 | 295 | fd_install(new_fd, get_file(fp[i])); |
1da177e4 LT |
296 | } |
297 | ||
298 | if (i > 0) | |
299 | { | |
300 | int cmlen = CMSG_LEN(i*sizeof(int)); | |
effee6a0 | 301 | err = put_user(SOL_SOCKET, &cm->cmsg_level); |
1da177e4 LT |
302 | if (!err) |
303 | err = put_user(SCM_RIGHTS, &cm->cmsg_type); | |
304 | if (!err) | |
305 | err = put_user(cmlen, &cm->cmsg_len); | |
306 | if (!err) { | |
307 | cmlen = CMSG_SPACE(i*sizeof(int)); | |
6900317f DB |
308 | if (msg->msg_controllen < cmlen) |
309 | cmlen = msg->msg_controllen; | |
1da177e4 LT |
310 | msg->msg_control += cmlen; |
311 | msg->msg_controllen -= cmlen; | |
312 | } | |
313 | } | |
314 | if (i < fdnum || (fdnum && fdmax <= 0)) | |
315 | msg->msg_flags |= MSG_CTRUNC; | |
316 | ||
317 | /* | |
318 | * All of the files that fit in the message have had their | |
319 | * usage counts incremented, so we just free the list. | |
320 | */ | |
321 | __scm_destroy(scm); | |
322 | } | |
9e34a5b5 | 323 | EXPORT_SYMBOL(scm_detach_fds); |
1da177e4 LT |
324 | |
325 | struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl) | |
326 | { | |
327 | struct scm_fp_list *new_fpl; | |
328 | int i; | |
329 | ||
330 | if (!fpl) | |
331 | return NULL; | |
332 | ||
bba14de9 ED |
333 | new_fpl = kmemdup(fpl, offsetof(struct scm_fp_list, fp[fpl->count]), |
334 | GFP_KERNEL); | |
1da177e4 | 335 | if (new_fpl) { |
bba14de9 | 336 | for (i = 0; i < fpl->count; i++) |
1da177e4 | 337 | get_file(fpl->fp[i]); |
bba14de9 | 338 | new_fpl->max = new_fpl->count; |
1da177e4 LT |
339 | } |
340 | return new_fpl; | |
341 | } | |
1da177e4 | 342 | EXPORT_SYMBOL(scm_fp_dup); |