1 /* scm.c - Socket level control messages processing.
3 * Author: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
4 * Alignment and value checking mods by Craig Metz
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.
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>
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>
31 #include <asm/uaccess.h>
33 #include <net/protocol.h>
34 #include <linux/skbuff.h>
36 #include <net/compat.h>
41 * Only allow a user to send credentials, that they could set with
45 static __inline__
int scm_check_creds(struct ucred
*creds
)
47 const struct cred
*cred
= current_cred();
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
))) {
59 static int scm_fp_copy(struct cmsghdr
*cmsg
, struct scm_fp_list
**fplp
)
61 int *fdp
= (int*)CMSG_DATA(cmsg
);
62 struct scm_fp_list
*fpl
= *fplp
;
66 num
= (cmsg
->cmsg_len
- CMSG_ALIGN(sizeof(struct cmsghdr
)))/sizeof(int);
76 fpl
= kmalloc(sizeof(struct scm_fp_list
), GFP_KERNEL
);
81 fpl
->max
= SCM_MAX_FD
;
83 fpp
= &fpl
->fp
[fpl
->count
];
85 if (fpl
->count
+ num
> fpl
->max
)
89 * Verify the descriptors and increment the usage count.
92 for (i
=0; i
< num
; i
++)
97 if (fd
< 0 || !(file
= fget_raw(fd
)))
105 void __scm_destroy(struct scm_cookie
*scm
)
107 struct scm_fp_list
*fpl
= scm
->fp
;
112 if (current
->scm_work_list
) {
113 list_add_tail(&fpl
->list
, current
->scm_work_list
);
115 LIST_HEAD(work_list
);
117 current
->scm_work_list
= &work_list
;
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
);
123 list_del(&fpl
->list
);
124 for (i
=fpl
->count
-1; i
>=0; i
--)
129 current
->scm_work_list
= NULL
;
133 EXPORT_SYMBOL(__scm_destroy
);
135 int __scm_send(struct socket
*sock
, struct msghdr
*msg
, struct scm_cookie
*p
)
137 struct cmsghdr
*cmsg
;
140 for (cmsg
= CMSG_FIRSTHDR(msg
); cmsg
; cmsg
= CMSG_NXTHDR(msg
, cmsg
))
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.
152 if (!CMSG_OK(msg
, cmsg
))
155 if (cmsg
->cmsg_level
!= SOL_SOCKET
)
158 switch (cmsg
->cmsg_type
)
161 if (!sock
->ops
|| sock
->ops
->family
!= PF_UNIX
)
163 err
=scm_fp_copy(cmsg
, &p
->fp
);
167 case SCM_CREDENTIALS
:
168 if (cmsg
->cmsg_len
!= CMSG_LEN(sizeof(struct ucred
)))
170 memcpy(&p
->creds
, CMSG_DATA(cmsg
), sizeof(struct ucred
));
171 err
= scm_check_creds(&p
->creds
);
175 if (!p
->pid
|| pid_vnr(p
->pid
) != p
->creds
.pid
) {
178 pid
= find_get_pid(p
->creds
.pid
);
186 (p
->cred
->euid
!= p
->creds
.uid
) ||
187 (p
->cred
->egid
!= p
->creds
.gid
)) {
190 cred
= prepare_creds();
194 cred
->uid
= cred
->euid
= p
->creds
.uid
;
195 cred
->gid
= cred
->egid
= p
->creds
.gid
;
206 if (p
->fp
&& !p
->fp
->count
)
217 EXPORT_SYMBOL(__scm_send
);
219 int put_cmsg(struct msghdr
* msg
, int level
, int type
, int len
, void *data
)
221 struct cmsghdr __user
*cm
222 = (__force
struct cmsghdr __user
*)msg
->msg_control
;
223 struct cmsghdr cmhdr
;
224 int cmlen
= CMSG_LEN(len
);
227 if (MSG_CMSG_COMPAT
& msg
->msg_flags
)
228 return put_cmsg_compat(msg
, level
, type
, len
, data
);
230 if (cm
==NULL
|| msg
->msg_controllen
< sizeof(*cm
)) {
231 msg
->msg_flags
|= MSG_CTRUNC
;
232 return 0; /* XXX: return error? check spec. */
234 if (msg
->msg_controllen
< cmlen
) {
235 msg
->msg_flags
|= MSG_CTRUNC
;
236 cmlen
= msg
->msg_controllen
;
238 cmhdr
.cmsg_level
= level
;
239 cmhdr
.cmsg_type
= type
;
240 cmhdr
.cmsg_len
= cmlen
;
243 if (copy_to_user(cm
, &cmhdr
, sizeof cmhdr
))
245 if (copy_to_user(CMSG_DATA(cm
), data
, cmlen
- sizeof(struct cmsghdr
)))
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
;
256 EXPORT_SYMBOL(put_cmsg
);
258 void scm_detach_fds(struct msghdr
*msg
, struct scm_cookie
*scm
)
260 struct cmsghdr __user
*cm
261 = (__force
struct cmsghdr __user
*)msg
->msg_control
;
264 int fdnum
= scm
->fp
->count
;
265 struct file
**fp
= scm
->fp
->fp
;
269 if (MSG_CMSG_COMPAT
& msg
->msg_flags
) {
270 scm_detach_fds_compat(msg
, scm
);
274 if (msg
->msg_controllen
> sizeof(struct cmsghdr
))
275 fdmax
= ((msg
->msg_controllen
- sizeof(struct cmsghdr
))
281 for (i
=0, cmfptr
=(__force
int __user
*)CMSG_DATA(cm
); i
<fdmax
;
285 err
= security_file_receive(fp
[i
]);
288 err
= get_unused_fd_flags(MSG_CMSG_CLOEXEC
& msg
->msg_flags
293 err
= put_user(new_fd
, cmfptr
);
295 put_unused_fd(new_fd
);
298 /* Bump the usage count and install the file. */
300 fd_install(new_fd
, fp
[i
]);
305 int cmlen
= CMSG_LEN(i
*sizeof(int));
306 err
= put_user(SOL_SOCKET
, &cm
->cmsg_level
);
308 err
= put_user(SCM_RIGHTS
, &cm
->cmsg_type
);
310 err
= put_user(cmlen
, &cm
->cmsg_len
);
312 cmlen
= CMSG_SPACE(i
*sizeof(int));
313 msg
->msg_control
+= cmlen
;
314 msg
->msg_controllen
-= cmlen
;
317 if (i
< fdnum
|| (fdnum
&& fdmax
<= 0))
318 msg
->msg_flags
|= MSG_CTRUNC
;
321 * All of the files that fit in the message have had their
322 * usage counts incremented, so we just free the list.
326 EXPORT_SYMBOL(scm_detach_fds
);
328 struct scm_fp_list
*scm_fp_dup(struct scm_fp_list
*fpl
)
330 struct scm_fp_list
*new_fpl
;
336 new_fpl
= kmemdup(fpl
, offsetof(struct scm_fp_list
, fp
[fpl
->count
]),
339 for (i
= 0; i
< fpl
->count
; i
++)
340 get_file(fpl
->fp
[i
]);
341 new_fpl
->max
= new_fpl
->count
;
345 EXPORT_SYMBOL(scm_fp_dup
);