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 for (i
=fpl
->count
-1; i
>=0; i
--)
117 EXPORT_SYMBOL(__scm_destroy
);
119 int __scm_send(struct socket
*sock
, struct msghdr
*msg
, struct scm_cookie
*p
)
121 struct cmsghdr
*cmsg
;
124 for (cmsg
= CMSG_FIRSTHDR(msg
); cmsg
; cmsg
= CMSG_NXTHDR(msg
, cmsg
))
128 /* Verify that cmsg_len is at least sizeof(struct cmsghdr) */
129 /* The first check was omitted in <= 2.2.5. The reasoning was
130 that parser checks cmsg_len in any case, so that
131 additional check would be work duplication.
132 But if cmsg_level is not SOL_SOCKET, we do not check
133 for too short ancillary data object at all! Oops.
136 if (!CMSG_OK(msg
, cmsg
))
139 if (cmsg
->cmsg_level
!= SOL_SOCKET
)
142 switch (cmsg
->cmsg_type
)
145 if (!sock
->ops
|| sock
->ops
->family
!= PF_UNIX
)
147 err
=scm_fp_copy(cmsg
, &p
->fp
);
151 case SCM_CREDENTIALS
:
152 if (cmsg
->cmsg_len
!= CMSG_LEN(sizeof(struct ucred
)))
154 memcpy(&p
->creds
, CMSG_DATA(cmsg
), sizeof(struct ucred
));
155 err
= scm_check_creds(&p
->creds
);
159 if (!p
->pid
|| pid_vnr(p
->pid
) != p
->creds
.pid
) {
162 pid
= find_get_pid(p
->creds
.pid
);
170 (p
->cred
->euid
!= p
->creds
.uid
) ||
171 (p
->cred
->egid
!= p
->creds
.gid
)) {
174 cred
= prepare_creds();
178 cred
->uid
= cred
->euid
= p
->creds
.uid
;
179 cred
->gid
= cred
->egid
= p
->creds
.gid
;
190 if (p
->fp
&& !p
->fp
->count
)
201 EXPORT_SYMBOL(__scm_send
);
203 int put_cmsg(struct msghdr
* msg
, int level
, int type
, int len
, void *data
)
205 struct cmsghdr __user
*cm
206 = (__force
struct cmsghdr __user
*)msg
->msg_control
;
207 struct cmsghdr cmhdr
;
208 int cmlen
= CMSG_LEN(len
);
211 if (MSG_CMSG_COMPAT
& msg
->msg_flags
)
212 return put_cmsg_compat(msg
, level
, type
, len
, data
);
214 if (cm
==NULL
|| msg
->msg_controllen
< sizeof(*cm
)) {
215 msg
->msg_flags
|= MSG_CTRUNC
;
216 return 0; /* XXX: return error? check spec. */
218 if (msg
->msg_controllen
< cmlen
) {
219 msg
->msg_flags
|= MSG_CTRUNC
;
220 cmlen
= msg
->msg_controllen
;
222 cmhdr
.cmsg_level
= level
;
223 cmhdr
.cmsg_type
= type
;
224 cmhdr
.cmsg_len
= cmlen
;
227 if (copy_to_user(cm
, &cmhdr
, sizeof cmhdr
))
229 if (copy_to_user(CMSG_DATA(cm
), data
, cmlen
- sizeof(struct cmsghdr
)))
231 cmlen
= CMSG_SPACE(len
);
232 if (msg
->msg_controllen
< cmlen
)
233 cmlen
= msg
->msg_controllen
;
234 msg
->msg_control
+= cmlen
;
235 msg
->msg_controllen
-= cmlen
;
240 EXPORT_SYMBOL(put_cmsg
);
242 void scm_detach_fds(struct msghdr
*msg
, struct scm_cookie
*scm
)
244 struct cmsghdr __user
*cm
245 = (__force
struct cmsghdr __user
*)msg
->msg_control
;
248 int fdnum
= scm
->fp
->count
;
249 struct file
**fp
= scm
->fp
->fp
;
253 if (MSG_CMSG_COMPAT
& msg
->msg_flags
) {
254 scm_detach_fds_compat(msg
, scm
);
258 if (msg
->msg_controllen
> sizeof(struct cmsghdr
))
259 fdmax
= ((msg
->msg_controllen
- sizeof(struct cmsghdr
))
265 for (i
=0, cmfptr
=(__force
int __user
*)CMSG_DATA(cm
); i
<fdmax
;
269 err
= security_file_receive(fp
[i
]);
272 err
= get_unused_fd_flags(MSG_CMSG_CLOEXEC
& msg
->msg_flags
277 err
= put_user(new_fd
, cmfptr
);
279 put_unused_fd(new_fd
);
282 /* Bump the usage count and install the file. */
284 fd_install(new_fd
, fp
[i
]);
289 int cmlen
= CMSG_LEN(i
*sizeof(int));
290 err
= put_user(SOL_SOCKET
, &cm
->cmsg_level
);
292 err
= put_user(SCM_RIGHTS
, &cm
->cmsg_type
);
294 err
= put_user(cmlen
, &cm
->cmsg_len
);
296 cmlen
= CMSG_SPACE(i
*sizeof(int));
297 msg
->msg_control
+= cmlen
;
298 msg
->msg_controllen
-= cmlen
;
301 if (i
< fdnum
|| (fdnum
&& fdmax
<= 0))
302 msg
->msg_flags
|= MSG_CTRUNC
;
305 * All of the files that fit in the message have had their
306 * usage counts incremented, so we just free the list.
310 EXPORT_SYMBOL(scm_detach_fds
);
312 struct scm_fp_list
*scm_fp_dup(struct scm_fp_list
*fpl
)
314 struct scm_fp_list
*new_fpl
;
320 new_fpl
= kmemdup(fpl
, offsetof(struct scm_fp_list
, fp
[fpl
->count
]),
323 for (i
= 0; i
< fpl
->count
; i
++)
324 get_file(fpl
->fp
[i
]);
325 new_fpl
->max
= new_fpl
->count
;
329 EXPORT_SYMBOL(scm_fp_dup
);
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