3 * $Id: check.c,v 1.8 1998/06/18 15:10:44 mdw Exp $
5 * Check validity of requests
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of `become'
14 * `Become' is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU General Public License as published by
16 * the Free Software Foundation; either version 2 of the License, or
17 * (at your option) any later version.
19 * `Become' is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU General Public License for more details.
24 * You should have received a copy of the GNU General Public License
25 * along with `become'; if not, write to the Free Software Foundation,
26 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
29 /*----- Revision history --------------------------------------------------*
32 * Revision 1.8 1998/06/18 15:10:44 mdw
33 * SECURITY HOLE: the file descriptor for the secret key was left open and
34 * inherited by the target process. This is now fixed. Also set
35 * close-on-exec flags on key file, close config file carefully, and close
36 * UDP socket after receiving reply from server.
38 * Revision 1.7 1998/04/23 13:22:08 mdw
39 * Support no-network configuration option, and new interface to
40 * configuration file parser.
42 * Revision 1.6 1998/01/12 16:45:47 mdw
45 * Revision 1.5 1997/09/26 09:14:58 mdw
46 * Merged blowfish branch into trunk.
48 * Revision 1.4.2.1 1997/09/26 09:08:01 mdw
49 * Use the Blowfish encryption algorithm instead of IDEA. This is partly
50 * because I prefer Blowfish (without any particularly strong evidence) but
51 * mainly because IDEA is patented and Blowfish isn't.
53 * Revision 1.4 1997/08/07 09:52:05 mdw
54 * (Log entry for previous version is bogus.) Added support for multiple
57 * Revision 1.2 1997/08/04 10:24:20 mdw
58 * Sources placed under CVS control.
60 * Revision 1.1 1997/07/21 13:47:53 mdw
65 /*----- Header files ------------------------------------------------------*/
67 /* --- ANSI headers --- */
76 /* --- Unix headers --- */
79 #include <sys/types.h>
80 #include <sys/socket.h>
82 #include <netinet/in.h>
84 #include <arpa/inet.h>
90 /* --- Local headers --- */
105 /*----- Client-end network support ----------------------------------------*/
109 /* --- @check__send@ --- *
111 * Arguments: @unsigned char *crq@ = pointer to encrypted request
112 * @int fd@ = socket to send from
113 * @struct sockaddr_in *serv@ = pointer to table of servers
114 * @size_t n_serv@ = number of servers
118 * Use: Sends the request packet to the list of servers. If the
119 * message couldn't be sent to any of them, an error is
123 static void check__send(unsigned char *crq
, int fd
,
124 struct sockaddr_in
*serv
, size_t n_serv
)
130 for (i
= 0; i
< n_serv
; i
++) {
131 if (sendto(fd
, (char *)crq
, crq_size
, 0,
132 (struct sockaddr
*)(serv
+ i
), sizeof(serv
[i
])) < 0) {
133 T( trace(TRACE_CLIENT
, "client: send to %s failed: %s",
134 inet_ntoa(serv
[i
].sin_addr
), strerror(errno
)); )
141 die("couldn't send request to server: %s", strerror(err
));
144 /* --- @check__ask@ --- *
146 * Arguments: @request *rq@ = pointer to request buffer
147 * @struct sockaddr_in *serv@ = pointer to table of servers
148 * @size_t n_serv@ = number of servers
150 * Returns: Nonzero if OK, zero if forbidden
152 * Use: Contacts a number of servers to decide whether the request
156 static int check__ask(request
*rq
, struct sockaddr_in
*serv
, size_t n_serv
)
159 unsigned char crq
[crq_size
];
160 unsigned char sk
[BLOWFISH_KEYSIZE
];
164 /* --- First, build the encrypted request packet --- */
167 unsigned char k
[BLOWFISH_KEYSIZE
];
170 /* --- Read in the encryption key --- */
172 if ((fp
= fopen(file_KEY
, "r")) == 0) {
173 die("couldn't open key file `%s': %s", file_KEY
,
176 if (fcntl(fileno(fp
), F_SETFD
, 1) < 0) {
177 die("couldn't set close-on-exec on key file `%s': %s", file_KEY
,
180 tx_getBits(k
, 128, fp
);
183 /* --- Now build a request packet --- */
187 crypt_packRequest(rq
, crq
, t
, pid
, k
, sk
);
189 T( trace(TRACE_CLIENT
, "client: encrypted request packet"); )
192 /* --- Create my socket --- */
195 struct sockaddr_in sin
;
197 if ((fd
= socket(PF_INET
, SOCK_DGRAM
, 0)) < 0)
198 die("couldn't create socket: %s", strerror(errno
));
200 /* --- Bind myself to some address --- */
202 sin
.sin_family
= AF_INET
;
204 sin
.sin_addr
.s_addr
= htonl(INADDR_ANY
);
206 if (bind(fd
, (struct sockaddr
*)&sin
, sizeof(sin
)) < 0)
207 die("couldn't bind socket to address: %s", strerror(errno
));
210 /* --- Now wait for a reply --- */
214 struct timeval start
, now
, tv
;
218 /* --- State table for waiting for replies --- *
220 * For each number, send off the request to our servers, and wait for
221 * that many seconds to have elapsed since we started. If the number is
222 * %$-1$% then it's time to give up.
225 static int tbl
[] = { 0, 5, 10, 20, -1 };
227 /* --- Find out when we are --- */
229 gettimeofday(&start
, 0);
232 /* --- Now loop until everything's done --- */
235 gettimeofday(&now
, 0);
237 /* --- If the current timer has expired, find one that hasn't --- *
239 * Also resend the request after I've found a timer which is still
240 * extant. If there aren't any, report an error.
243 if (now
.tv_sec
>= start
.tv_sec
+ tbl
[ind
] &&
244 now
.tv_usec
>= start
.tv_usec
) {
248 die("no reply from servers");
249 } while (now
.tv_sec
>= start
.tv_sec
+ tbl
[ind
] &&
250 now
.tv_usec
>= start
.tv_usec
);
251 check__send(crq
, fd
, serv
, n_serv
);
252 T( trace(TRACE_CLIENT
, "client: send request to servers"); )
255 /* --- Now wait for a packet to arrive --- */
257 if (now
.tv_usec
> start
.tv_usec
) {
258 now
.tv_usec
-= 1000000;
261 tv
.tv_sec
= start
.tv_sec
+ tbl
[ind
] - now
.tv_sec
;
262 tv
.tv_usec
= start
.tv_usec
- now
.tv_usec
;
264 /* --- Sort out file descriptors to watch --- */
269 /* --- Wait for them --- */
271 i
= select(FD_SETSIZE
, &fds
, 0, 0, &tv
);
272 if (i
== 0 || (i
< 0 && errno
== EINTR
))
275 die("error waiting for reply: %s", strerror(errno
));
277 /* --- A reply should be waiting now --- */
280 struct sockaddr_in sin
;
281 int slen
= sizeof(sin
);
282 unsigned char buff
[256];
285 /* --- Read the reply data --- */
287 if (recvfrom(fd
, (char *)buff
, sizeof(buff
), 0,
288 (struct sockaddr
*)&sin
, &slen
) < 0)
289 die("error reading server's reply: %s", strerror(errno
));
291 IF_TRACING(TRACE_CLIENT
, {
292 struct hostent
*h
= gethostbyaddr((char *)&sin
.sin_addr
,
293 sizeof(sin
.sin_addr
), AF_INET
);
294 trace(TRACE_CLIENT
, "client: reply received from %s port %i",
295 h ? h
->h_name
: inet_ntoa(sin
.sin_addr
),
296 ntohs(sin
.sin_port
));
299 /* --- Verify the sender --- *
301 * This is more to avoid confusion than for security: an active
302 * attacker is quite capable of forging the source address. We rely
303 * on the checksum in the reply packet for authentication.
306 for (i
= 0; i
< n_serv
; i
++) {
307 if (sin
.sin_addr
.s_addr
== serv
[i
].sin_addr
.s_addr
&&
308 sin
.sin_port
== serv
[i
].sin_port
)
312 T( trace(TRACE_CLIENT
, "client: reply from unknown host"); )
316 /* --- Unpack and verify the response --- */
318 answer
= crypt_unpackReply(buff
, sk
, t
, pid
);
320 T( trace(TRACE_CLIENT
,
321 "client: invalid or corrupt reply packet"); )
330 die("internal error: can't get here in check__ask");
334 /* --- @check__client@ --- *
336 * Arguments: @request *rq@ = pointer to a request block
337 * @FILE *fp@ = file containing server configuration
339 * Returns: Nonzero if OK, zero if forbidden
341 * Use: Asks one or several servers whether a request is acceptable.
344 int check__client(request
*rq
, FILE *fp
)
346 /* --- Format of the file --- *
348 * The `servers' file contains entries of the form
350 * %%\syntax{<host> [`:' <port>]}%%
352 * separates by whitespace. I build them all into an array of socket
353 * addresses and pass the whole lot to another function.
356 struct sockaddr_in
*serv
; /* Array of servers */
357 size_t n_serv
, max_serv
; /* Number and maximum number */
359 /* --- Initialise the server array --- */
361 T( trace(TRACE_CLIENT
, "client: reading server definitions"); )
362 n_serv
= 0; max_serv
= 4; /* Four seems reasonable */
363 serv
= xmalloc(sizeof(*serv
) * max_serv
);
365 /* --- Start reading the file --- */
368 char buff
[256], *p
, *l
; /* A buffer and pointers for it */
369 int port
; /* Default port for servers */
370 int state
; /* Current parser state */
371 struct in_addr t_host
; /* Temp place for an address*/
372 int t_port
; /* Temp place for a port */
373 int ch
; /* The current character */
375 /* --- Parser states --- */
378 st_start
, /* Waiting to begin */
379 st_host
, /* Reading a new hostname */
380 st_colon
, /* Expecting a colon, maybe */
381 st_preport
, /* Waiting before reading port */
382 st_port
, /* Reading a port number */
383 st_commit
, /* Commit a newly read server */
384 st_done
/* Finished reading the file */
387 /* --- Find a default port --- */
390 struct servent
*s
= getservbyname(quis(), "udp");
391 port
= (s ? s
->s_port
: -1);
394 /* --- Initialise for scanning the file --- */
398 l
= buff
+ sizeof(buff
);
402 /* --- Go for it --- */
404 while (state
!= st_done
) {
407 /* --- Initial whitespace before hostname --- */
412 else if (isspace((unsigned char)ch
))
418 /* --- Read a host name --- */
422 die("string too long in `" file_SERVER
"'");
423 if (ch
!= EOF
&& !isspace((unsigned char)ch
) && ch
!= ':') {
430 if ((h
= gethostbyname(buff
)) == 0)
431 die("unknown host `%s' in `" file_SERVER
"'", buff
);
432 memcpy(&t_host
, h
->h_addr
, sizeof(t_host
));
437 /* --- Waiting for a colon coming up --- */
442 else if (isspace((unsigned char)ch
))
444 else if (ch
== ':') {
452 /* --- Clearing whitespace before a port number --- */
457 else if (isspace((unsigned char)ch
))
465 /* --- Read a port number --- */
469 die("string too long in `" file_SERVER
"'");
470 if (ch
!= EOF
&& !isspace((unsigned char)ch
) && ch
!= ':') {
477 s
= getservbyname(buff
, "udp");
478 if (!s
&& isdigit((unsigned char)buff
[0]))
479 t_port
= htons(atoi(buff
));
481 die("unknown service `%s' in `" file_SERVER
"'", buff
);
488 /* --- A server has been read successfully --- */
491 if (n_serv
== max_serv
) {
493 serv
= xrealloc(serv
, max_serv
* sizeof(*serv
));
495 serv
[n_serv
].sin_family
= AF_INET
;
496 serv
[n_serv
].sin_addr
= t_host
;
497 serv
[n_serv
].sin_port
= t_port
;
504 /* --- A safety net for a broken parser --- */
507 die("internal error: can't get here in check__client");
515 /* --- Now start sending requests --- */
518 die("no servers specified in `" file_SERVER
"'");
520 IF_TRACING(TRACE_CLIENT
, {
523 for (i
= 0; i
< n_serv
; i
++) {
524 trace(TRACE_CLIENT
, "client: server %s port %i",
525 inet_ntoa(serv
[i
].sin_addr
), ntohs(serv
[i
].sin_port
));
528 return (check__ask(rq
, serv
, n_serv
));
533 /*----- Main checking function --------------------------------------------*/
537 * Arguments: @request *rq@ = pointer to request buffer
539 * Returns: Nonzero if OK, zero if forbidden
541 * Use: Checks to see if the request is acceptable.
544 int check(request
*rq
)
548 /* --- Check if we need to talk to a server --- */
551 if ((fp
= fopen(file_SERVER
, "r")) != 0)
552 return (check__client(rq
, fp
));
555 /* --- Otherwise do this all the old-fashioned way --- */
557 if ((fp
= fopen(file_RULES
, "r")) == 0) {
558 die("couldn't read configuration file `%s': %s",
559 file_RULES
, strerror(errno
));
572 return (rule_check(rq
));
575 /*----- That's all, folks -------------------------------------------------*/