Commit | Line | Data |
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9da480be MW |
1 | /* -*-c-*- |
2 | * | |
3 | * Main daemon | |
4 | * | |
5 | * (c) 2012 Straylight/Edgeware | |
6 | */ | |
7 | ||
8 | /*----- Licensing notice --------------------------------------------------* | |
9 | * | |
10 | * This file is part of Yet Another Ident Daemon (YAID). | |
11 | * | |
12 | * YAID is free software; you can redistribute it and/or modify | |
13 | * it under the terms of the GNU General Public License as published by | |
14 | * the Free Software Foundation; either version 2 of the License, or | |
15 | * (at your option) any later version. | |
16 | * | |
17 | * YAID is distributed in the hope that it will be useful, | |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | * GNU General Public License for more details. | |
21 | * | |
22 | * You should have received a copy of the GNU General Public License | |
23 | * along with YAID; if not, write to the Free Software Foundation, | |
24 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
25 | */ | |
26 | ||
27 | /*----- Header files ------------------------------------------------------*/ | |
28 | ||
29 | #include "yaid.h" | |
30 | ||
31 | /*----- Data structures ---------------------------------------------------*/ | |
32 | ||
c3794524 MW |
33 | /* A write buffer is the gadget which keeps track of our output and writes |
34 | * portions of it out as and when connections are ready for it. | |
35 | */ | |
9da480be MW |
36 | #define WRBUFSZ 1024 |
37 | struct writebuf { | |
c3794524 MW |
38 | size_t o; /* Offset of remaining data */ |
39 | size_t n; /* Length of remaining data */ | |
40 | sel_file wr; /* Write selector */ | |
41 | void (*func)(int /*err*/, void *); /* Function to call on completion */ | |
42 | void *p; /* Context for `func' */ | |
43 | unsigned char buf[WRBUFSZ]; /* Output buffer */ | |
9da480be MW |
44 | }; |
45 | ||
c3794524 MW |
46 | /* Structure for a listening socket. There's one of these for each address |
47 | * family we're looking after. | |
48 | */ | |
49 | struct listen { | |
50 | const struct addrops *ao; /* Address family operations */ | |
51 | sel_file f; /* Watch for incoming connections */ | |
9da480be MW |
52 | }; |
53 | ||
c3794524 | 54 | /* The main structure for a client. */ |
9da480be | 55 | struct client { |
c3794524 MW |
56 | int fd; /* The connection to the client */ |
57 | selbuf b; /* Accumulate lines of input */ | |
58 | struct query q; /* The clients query and our reply */ | |
4f8fdcc1 | 59 | struct sel_timer t; /* Timeout for idle or doomed conn */ |
c3794524 MW |
60 | struct listen *l; /* Back to the listener (and ops) */ |
61 | struct writebuf wb; /* Write buffer for our reply */ | |
62 | struct proxy *px; /* Proxy if conn goes via NAT */ | |
63 | }; | |
64 | ||
65 | /* A proxy connection. */ | |
66 | struct proxy { | |
67 | int fd; /* Connection; -1 if in progress */ | |
68 | struct client *c; /* Back to the client */ | |
69 | conn cn; /* Nonblocking connection */ | |
70 | selbuf b; /* Accumulate the response line */ | |
71 | struct writebuf wb; /* Write buffer for query */ | |
72 | char nat[ADDRLEN]; /* Server address, as text */ | |
9da480be MW |
73 | }; |
74 | ||
75 | /*----- Static variables --------------------------------------------------*/ | |
76 | ||
c3794524 | 77 | static sel_state sel; /* I/O multiplexer state */ |
9da480be | 78 | |
c3794524 MW |
79 | static const struct policy default_policy = POLICY_INIT(A_NAME); |
80 | static policy_v policy = DA_INIT; /* Vector of global policy rules */ | |
81 | static fwatch polfw; /* Watch policy file for changes */ | |
9da480be | 82 | |
c3794524 MW |
83 | static unsigned char tokenbuf[4096]; /* Random-ish data for tokens */ |
84 | static size_t tokenptr = sizeof(tokenbuf); /* Current read position */ | |
85 | static int randfd; /* File descriptor for random data */ | |
9da480be | 86 | |
c3794524 | 87 | /*----- Ident protocol parsing --------------------------------------------*/ |
9da480be | 88 | |
c3794524 MW |
89 | /* Advance *PP over whitespace characters. */ |
90 | static void skipws(const char **pp) | |
91 | { while (isspace((unsigned char )**pp)) (*pp)++; } | |
92 | ||
93 | /* Copy a token of no more than N bytes starting at *PP into Q, advancing *PP | |
94 | * over it. | |
95 | */ | |
96 | static int idtoken(const char **pp, char *q, size_t n) | |
9da480be | 97 | { |
c3794524 | 98 | const char *p = *pp; |
9da480be | 99 | |
c3794524 MW |
100 | skipws(&p); |
101 | n--; | |
102 | for (;;) { | |
103 | if (*p == ':' || *p <= 32 || *p >= 127) break; | |
104 | if (!n) return (-1); | |
105 | *q++ = *p++; | |
106 | n--; | |
9da480be | 107 | } |
c3794524 MW |
108 | *q++ = 0; |
109 | *pp = p; | |
110 | return (0); | |
111 | } | |
112 | ||
113 | /* Read an unsigned decimal number from *PP, and store it in *II. Check that | |
114 | * it's between MIN and MAX, and advance *PP over it. Return zero for | |
115 | * success, or nonzero if something goes wrong. | |
116 | */ | |
117 | static int unum(const char **pp, unsigned *ii, unsigned min, unsigned max) | |
118 | { | |
119 | char *q; | |
120 | unsigned long i; | |
121 | int e; | |
122 | ||
123 | skipws(pp); | |
124 | if (!isdigit((unsigned char)**pp)) return (-1); | |
125 | e = errno; errno = 0; | |
126 | i = strtoul(*pp, &q, 10); | |
127 | if (errno) return (-1); | |
128 | *pp = q; | |
129 | errno = e; | |
130 | if (i < min || i > max) return (-1); | |
131 | *ii = i; | |
132 | return (0); | |
9da480be MW |
133 | } |
134 | ||
c3794524 MW |
135 | /*----- Asynchronous writing ----------------------------------------------*/ |
136 | ||
137 | /* Callback for actually writing stuff from a `writebuf'. */ | |
9da480be MW |
138 | static void write_out(int fd, unsigned mode, void *p) |
139 | { | |
140 | ssize_t n; | |
141 | struct writebuf *wb = p; | |
142 | ||
c3794524 | 143 | /* Try to write something. */ |
9da480be MW |
144 | if ((n = write(fd, wb->buf + wb->o, wb->n)) < 0) { |
145 | if (errno == EAGAIN || errno == EWOULDBLOCK) return; | |
146 | wb->n = 0; | |
147 | sel_rmfile(&wb->wr); | |
148 | wb->func(errno, wb->p); | |
149 | } | |
150 | wb->o += n; | |
151 | wb->n -= n; | |
c3794524 MW |
152 | |
153 | /* If there's nothing left then restore the buffer to its empty state. */ | |
9da480be MW |
154 | if (!wb->n) { |
155 | wb->o = 0; | |
156 | sel_rmfile(&wb->wr); | |
157 | wb->func(0, wb->p); | |
158 | } | |
159 | } | |
160 | ||
c3794524 | 161 | /* Queue N bytes starting at P to be written. */ |
9da480be MW |
162 | static int queue_write(struct writebuf *wb, const void *p, size_t n) |
163 | { | |
c3794524 | 164 | /* Maybe there's nothing to actually do. */ |
9da480be | 165 | if (!n) return (0); |
c3794524 MW |
166 | |
167 | /* Make sure it'll fit. */ | |
9da480be | 168 | if (wb->n - wb->o + n > WRBUFSZ) return (-1); |
c3794524 MW |
169 | |
170 | /* If there's anything there already, then make sure it's at the start of | |
171 | * the available space. | |
172 | */ | |
9da480be MW |
173 | if (wb->o) { |
174 | memmove(wb->buf, wb->buf + wb->o, wb->n); | |
175 | wb->o = 0; | |
176 | } | |
c3794524 MW |
177 | |
178 | /* If there's nothing currently there, then we're not requesting write | |
179 | * notifications, so set that up, and force an initial wake-up. | |
180 | */ | |
9da480be MW |
181 | if (!wb->n) { |
182 | sel_addfile(&wb->wr); | |
183 | sel_force(&wb->wr); | |
184 | } | |
c3794524 MW |
185 | |
186 | /* Copy the new material over. */ | |
187 | memcpy(wb->buf + wb->n, p, n); | |
9da480be | 188 | wb->n += n; |
c3794524 MW |
189 | |
190 | /* Done. */ | |
9da480be MW |
191 | return (0); |
192 | } | |
193 | ||
c3794524 | 194 | /* Release resources allocated to WB. */ |
9da480be MW |
195 | static void free_writebuf(struct writebuf *wb) |
196 | { if (wb->n) sel_rmfile(&wb->wr); } | |
197 | ||
c3794524 MW |
198 | /* Initialize a writebuf in *WB, writing to file descriptor FD. On |
199 | * completion, call FUNC, passing it P and an error indicator: either 0 for | |
200 | * success or an `errno' value on failure. | |
201 | */ | |
9da480be MW |
202 | static void init_writebuf(struct writebuf *wb, |
203 | int fd, void (*func)(int, void *), void *p) | |
204 | { | |
205 | sel_initfile(&sel, &wb->wr, fd, SEL_WRITE, write_out, wb); | |
206 | wb->func = func; | |
207 | wb->p = p; | |
208 | wb->n = wb->o = 0; | |
209 | } | |
210 | ||
c3794524 | 211 | /*----- General utilities -------------------------------------------------*/ |
9da480be | 212 | |
c3794524 MW |
213 | /* Format and log MSG somewhere sensible, at the syslog(3) priority PRIO. |
214 | * Prefix it with a description of the query Q, if non-null. | |
215 | */ | |
216 | void logmsg(const struct query *q, int prio, const char *msg, ...) | |
9da480be | 217 | { |
c3794524 MW |
218 | va_list ap; |
219 | dstr d = DSTR_INIT; | |
220 | ||
221 | va_start(ap, msg); | |
222 | if (q) { | |
223 | dputsock(&d, q->ao, &q->s[L]); | |
224 | dstr_puts(&d, " <-> "); | |
225 | dputsock(&d, q->ao, &q->s[R]); | |
226 | dstr_puts(&d, ": "); | |
227 | } | |
228 | dstr_vputf(&d, msg, &ap); | |
229 | va_end(ap); | |
230 | fprintf(stderr, "yaid: %s\n", d.buf); | |
231 | dstr_destroy(&d); | |
9da480be MW |
232 | } |
233 | ||
c3794524 MW |
234 | /* Fix up a socket FD so that it won't bite us. Returns zero on success, or |
235 | * nonzero on error. | |
236 | */ | |
95df134c MW |
237 | static int fix_up_socket(int fd, const char *what) |
238 | { | |
239 | int yes = 1; | |
240 | ||
241 | if (fdflags(fd, O_NONBLOCK, O_NONBLOCK, 0, 0)) { | |
242 | logmsg(0, LOG_ERR, "failed to set %s connection nonblocking: %s", | |
243 | what, strerror(errno)); | |
244 | return (-1); | |
245 | } | |
246 | ||
247 | if (setsockopt(fd, SOL_SOCKET, SO_OOBINLINE, &yes, sizeof(yes))) { | |
248 | logmsg(0, LOG_ERR, | |
249 | "failed to disable `out-of-band' data on %s connection: %s", | |
250 | what, strerror(errno)); | |
251 | return (-1); | |
252 | } | |
253 | ||
254 | return (0); | |
255 | } | |
256 | ||
c3794524 MW |
257 | /*----- Client output functions -------------------------------------------*/ |
258 | ||
259 | static void disconnect_client(struct client *c); | |
260 | ||
261 | /* Notification that output has been written. If successful, re-enable the | |
262 | * input buffer and prepare for another query. | |
263 | */ | |
9da480be MW |
264 | static void done_client_write(int err, void *p) |
265 | { | |
266 | struct client *c = p; | |
267 | ||
268 | if (!err) | |
269 | selbuf_enable(&c->b); | |
270 | else { | |
271 | logmsg(&c->q, LOG_ERR, "failed to send reply: %s", strerror(err)); | |
272 | disconnect_client(c); | |
273 | } | |
274 | } | |
275 | ||
c3794524 MW |
276 | /* Format the message FMT and queue it to be sent to the client. Client |
277 | * input will be disabled until the write completes. | |
278 | */ | |
9da480be MW |
279 | static void write_to_client(struct client *c, const char *fmt, ...) |
280 | { | |
281 | va_list ap; | |
282 | char buf[WRBUFSZ]; | |
283 | ssize_t n; | |
284 | ||
285 | va_start(ap, fmt); | |
286 | n = vsnprintf(buf, sizeof(buf), fmt, ap); | |
287 | if (n < 0) { | |
288 | logmsg(&c->q, LOG_ERR, "failed to format output: %s", strerror(errno)); | |
289 | disconnect_client(c); | |
290 | return; | |
291 | } else if (n > sizeof(buf)) { | |
292 | logmsg(&c->q, LOG_ERR, "output too long for client send buffer"); | |
293 | disconnect_client(c); | |
294 | return; | |
295 | } | |
296 | ||
297 | selbuf_disable(&c->b); | |
298 | if (queue_write(&c->wb, buf, n)) { | |
299 | logmsg(&c->q, LOG_ERR, "write buffer overflow"); | |
300 | disconnect_client(c); | |
301 | } | |
302 | } | |
303 | ||
c3794524 MW |
304 | /* Format a reply to the client, with the form LPORT:RPORT:TY:TOK0[:TOK1]. |
305 | * Typically, TY will be `ERROR' or `USERID'. In the former case, TOK0 will | |
306 | * be the error token and TOK1 will be null; in the latter case, TOK0 will be | |
307 | * the operating system and TOK1 the user name. | |
308 | */ | |
c809f908 MW |
309 | static void reply(struct client *c, const char *ty, |
310 | const char *tok0, const char *tok1) | |
9da480be | 311 | { |
c809f908 MW |
312 | write_to_client(c, "%u,%u:%s:%s%s%s\r\n", |
313 | c->q.s[L].port, c->q.s[R].port, ty, | |
314 | tok0, tok1 ? ":" : "", tok1 ? tok1 : ""); | |
9da480be MW |
315 | } |
316 | ||
c3794524 | 317 | /* Mapping from error codes to their protocol tokens. */ |
bf4d9761 MW |
318 | const char *const errtok[] = { |
319 | #define DEFTOK(err, tok) tok, | |
320 | ERROR(DEFTOK) | |
321 | #undef DEFTOK | |
322 | }; | |
323 | ||
c3794524 | 324 | /* Report an error with code ERR to the client. */ |
9da480be MW |
325 | static void reply_error(struct client *c, unsigned err) |
326 | { | |
327 | assert(err < E_LIMIT); | |
c809f908 | 328 | reply(c, "ERROR", errtok[err], 0); |
9da480be MW |
329 | } |
330 | ||
c3794524 | 331 | /*----- NAT proxy functions -----------------------------------------------*/ |
9da480be | 332 | |
c3794524 MW |
333 | /* Cancel the proxy operation PX, closing the connection and releasing |
334 | * resources. This is used for both normal and unexpected closures. | |
335 | */ | |
336 | static void cancel_proxy(struct proxy *px) | |
9da480be | 337 | { |
c3794524 MW |
338 | if (px->fd == -1) |
339 | conn_kill(&px->cn); | |
340 | else { | |
341 | close(px->fd); | |
342 | selbuf_destroy(&px->b); | |
343 | free_writebuf(&px->wb); | |
9da480be | 344 | } |
c3794524 MW |
345 | selbuf_enable(&px->c->b); |
346 | px->c->px = 0; | |
347 | xfree(px); | |
9da480be MW |
348 | } |
349 | ||
c3794524 MW |
350 | /* Notification that a line (presumably a reply) has been received from the |
351 | * server. We should check it, log it, and propagate the answer back. | |
352 | * Whatever happens, this proxy operation is now complete. | |
353 | */ | |
9da480be MW |
354 | static void proxy_line(char *line, size_t sz, void *p) |
355 | { | |
356 | struct proxy *px = p; | |
357 | char buf[1024]; | |
358 | const char *q = line; | |
359 | unsigned lp, rp; | |
360 | ||
c3794524 | 361 | /* Trim trailing space. */ |
9da480be | 362 | while (sz && isspace((unsigned char)line[sz - 1])) sz--; |
9da480be | 363 | |
c3794524 | 364 | /* Parse the port numbers. These should match the request. */ |
9da480be MW |
365 | if (unum(&q, &lp, 1, 65535)) goto syntax; |
366 | skipws(&q); if (*q != ',') goto syntax; q++; | |
367 | if (unum(&q, &rp, 1, 65535)) goto syntax; | |
368 | skipws(&q); if (*q != ':') goto syntax; q++; | |
369 | if (lp != px->c->q.u.nat.port || rp != px->c->q.s[R].port) goto syntax; | |
c3794524 MW |
370 | |
371 | /* Find out what kind of reply this is. */ | |
9da480be MW |
372 | if (idtoken(&q, buf, sizeof(buf))) goto syntax; |
373 | skipws(&q); if (*q != ':') goto syntax; q++; | |
c3794524 | 374 | |
9da480be | 375 | if (strcmp(buf, "ERROR") == 0) { |
c3794524 MW |
376 | |
377 | /* Report the error without interpreting it. It might be meaningful to | |
378 | * the client. | |
379 | */ | |
9da480be MW |
380 | skipws(&q); |
381 | logmsg(&px->c->q, LOG_ERR, "proxy error from %s: %s", px->nat, q); | |
c809f908 | 382 | reply(px->c, "ERROR", q, 0); |
c3794524 | 383 | |
9da480be | 384 | } else if (strcmp(buf, "USERID") == 0) { |
c3794524 MW |
385 | |
386 | /* Parse out the operating system and user name, and pass them on. */ | |
9da480be MW |
387 | if (idtoken(&q, buf, sizeof(buf))) goto syntax; |
388 | skipws(&q); if (*q != ':') goto syntax; q++; | |
389 | skipws(&q); | |
390 | logmsg(&px->c->q, LOG_ERR, "user `%s'; proxy = %s, os = %s", | |
391 | q, px->nat, buf); | |
c809f908 | 392 | reply(px->c, "USERID", buf, q); |
c3794524 | 393 | |
9da480be MW |
394 | } else |
395 | goto syntax; | |
396 | goto done; | |
397 | ||
398 | syntax: | |
c3794524 | 399 | /* We didn't understand the message from the client. */ |
9da480be MW |
400 | logmsg(&px->c->q, LOG_ERR, "failed to parse response from %s", px->nat); |
401 | reply_error(px->c, E_UNKNOWN); | |
402 | done: | |
c3794524 | 403 | /* All finished, no matter what. */ |
9da480be MW |
404 | cancel_proxy(px); |
405 | } | |
406 | ||
c3794524 MW |
407 | /* Notification that we have written the query to the server. Await a |
408 | * response if successful. | |
409 | */ | |
9da480be MW |
410 | static void done_proxy_write(int err, void *p) |
411 | { | |
412 | struct proxy *px = p; | |
413 | ||
414 | if (err) { | |
415 | logmsg(&px->c->q, LOG_ERR, "failed to proxy query to %s: %s", | |
416 | px->nat, strerror(errno)); | |
417 | reply_error(px->c, E_UNKNOWN); | |
418 | cancel_proxy(px); | |
419 | return; | |
420 | } | |
421 | selbuf_enable(&px->b); | |
422 | } | |
423 | ||
c3794524 MW |
424 | /* Notification that the connection to the server is either established or |
425 | * failed. In the former case, queue the right query. | |
426 | */ | |
9da480be MW |
427 | static void proxy_connected(int fd, void *p) |
428 | { | |
429 | struct proxy *px = p; | |
430 | char buf[16]; | |
431 | int n; | |
432 | ||
c3794524 | 433 | /* If the connection failed then report the problem and give up. */ |
9da480be MW |
434 | if (fd < 0) { |
435 | logmsg(&px->c->q, LOG_ERR, | |
436 | "failed to make %s proxy connection to %s: %s", | |
bf4d9761 | 437 | px->c->l->ao->name, px->nat, strerror(errno)); |
9da480be MW |
438 | reply_error(px->c, E_UNKNOWN); |
439 | cancel_proxy(px); | |
440 | return; | |
441 | } | |
442 | ||
c3794524 | 443 | /* We're now ready to go, so set things up. */ |
9da480be MW |
444 | px->fd = fd; |
445 | selbuf_init(&px->b, &sel, fd, proxy_line, px); | |
446 | selbuf_setsize(&px->b, 1024); | |
447 | selbuf_disable(&px->b); | |
448 | init_writebuf(&px->wb, fd, done_proxy_write, px); | |
449 | ||
c3794524 MW |
450 | /* Write the query. This buffer is large enough because we've already |
451 | * range-checked the remote the port number and the local one came from the | |
452 | * kernel, which we trust not to do anything stupid. | |
453 | */ | |
9da480be MW |
454 | n = sprintf(buf, "%u,%u\r\n", px->c->q.u.nat.port, px->c->q.s[R].port); |
455 | queue_write(&px->wb, buf, n); | |
456 | } | |
457 | ||
c3794524 MW |
458 | /* Proxy the query through to a client machine for which we're providing NAT |
459 | * disservice. | |
460 | */ | |
9da480be MW |
461 | static void proxy_query(struct client *c) |
462 | { | |
463 | struct socket s; | |
464 | struct sockaddr_storage ss; | |
465 | size_t ssz; | |
466 | struct proxy *px; | |
9da480be MW |
467 | int fd; |
468 | ||
c3794524 | 469 | /* Allocate the context structure for the NAT. */ |
9da480be | 470 | px = xmalloc(sizeof(*px)); |
c3794524 MW |
471 | |
472 | /* We'll use the client host's address in lots of log messages, so we may | |
473 | * as well format it once and use it over and over. | |
474 | */ | |
bf4d9761 | 475 | inet_ntop(c->q.ao->af, &c->q.u.nat.addr, px->nat, sizeof(px->nat)); |
9da480be | 476 | |
c3794524 | 477 | /* Create the socket for the connection. */ |
bf4d9761 | 478 | if ((fd = socket(c->q.ao->af, SOCK_STREAM, 0)) < 0) { |
9da480be | 479 | logmsg(&c->q, LOG_ERR, "failed to make %s socket for proxy: %s", |
bf4d9761 | 480 | c->l->ao->name, strerror(errno)); |
9da480be MW |
481 | goto err_0; |
482 | } | |
95df134c | 483 | if (fix_up_socket(fd, "proxy")) goto err_1; |
9da480be | 484 | |
c3794524 MW |
485 | /* Set up the connection to the client host. The connection interface is a |
486 | * bit broken: if the connection completes immediately, then the callback | |
487 | * function is called synchronously, and that might decide to shut | |
488 | * everything down. So we must have fully initialized our context before | |
489 | * calling `conn_init', and mustn't touch it again afterwards -- since the | |
490 | * block may have been freed. | |
491 | */ | |
9da480be MW |
492 | s = c->q.u.nat; |
493 | s.port = 113; | |
bf4d9761 | 494 | c->l->ao->socket_to_sockaddr(&s, &ss, &ssz); |
9da480be | 495 | selbuf_disable(&c->b); |
79805e61 MW |
496 | c->px = px; px->c = c; |
497 | px->fd = -1; | |
9da480be MW |
498 | if (conn_init(&px->cn, &sel, fd, (struct sockaddr *)&ss, ssz, |
499 | proxy_connected, px)) { | |
500 | logmsg(&c->q, LOG_ERR, "failed to make %s proxy connection to %s: %s", | |
bf4d9761 | 501 | c->l->ao->name, px->nat, strerror(errno)); |
9da480be MW |
502 | goto err_2; |
503 | } | |
504 | ||
c3794524 | 505 | /* All ready to go. */ |
9da480be MW |
506 | return; |
507 | ||
c3794524 | 508 | /* Tidy up after various kinds of failures. */ |
9da480be MW |
509 | err_2: |
510 | selbuf_enable(&c->b); | |
511 | err_1: | |
512 | close(px->fd); | |
513 | err_0: | |
514 | xfree(px); | |
515 | reply_error(c, E_UNKNOWN); | |
516 | } | |
517 | ||
c3794524 MW |
518 | /*----- Client connection functions ---------------------------------------*/ |
519 | ||
520 | /* Disconnect a client, freeing up any associated resources. */ | |
521 | static void disconnect_client(struct client *c) | |
522 | { | |
523 | close(c->fd); | |
524 | selbuf_destroy(&c->b); | |
4f8fdcc1 | 525 | sel_rmtimer(&c->t); |
c3794524 MW |
526 | free_writebuf(&c->wb); |
527 | if (c->px) cancel_proxy(c->px); | |
528 | xfree(c); | |
529 | } | |
9da480be | 530 | |
4f8fdcc1 MW |
531 | /* Time out a client because it's been idle for too long. */ |
532 | static void timeout_client(struct timeval *tv, void *p) | |
533 | { | |
534 | struct client *c = p; | |
535 | logmsg(&c->q, LOG_NOTICE, "timing out idle or stuck client"); | |
536 | sel_addtimer(&sel, &c->t, tv, timeout_client, 0); | |
537 | disconnect_client(c); | |
538 | } | |
539 | ||
540 | /* Reset the client idle timer, as a result of activity. Set EXISTP if | |
541 | * there is an existing timer which needs to be removed. | |
542 | */ | |
543 | static void reset_client_timer(struct client *c, int existp) | |
544 | { | |
545 | struct timeval tv; | |
546 | ||
547 | gettimeofday(&tv, 0); | |
548 | tv.tv_sec += 30; | |
549 | if (existp) sel_rmtimer(&c->t); | |
550 | sel_addtimer(&sel, &c->t, &tv, timeout_client, c); | |
551 | } | |
552 | ||
c3794524 MW |
553 | /* Write a pseudorandom token into the buffer at P, which must have space for |
554 | * at least TOKENSZ bytes. | |
555 | */ | |
556 | #define TOKENRANDSZ 8 | |
557 | #define TOKENSZ ((4*TOKENRANDSZ + 5)/3) | |
9da480be MW |
558 | static void user_token(char *p) |
559 | { | |
9da480be MW |
560 | unsigned a = 0; |
561 | unsigned b = 0; | |
562 | int i; | |
c3794524 MW |
563 | static const char tokmap[64] = |
564 | "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789.-"; | |
9da480be | 565 | |
c3794524 MW |
566 | /* If there's not enough pseudorandom stuff lying around, then read more |
567 | * from the kernel. | |
568 | */ | |
569 | if (tokenptr + TOKENRANDSZ >= sizeof(tokenbuf)) { | |
9da480be MW |
570 | if (read(randfd, tokenbuf, sizeof(tokenbuf)) < sizeof(tokenbuf)) |
571 | die(1, "unexpected short read or error from `/dev/urandom'"); | |
572 | tokenptr = 0; | |
573 | } | |
574 | ||
c3794524 MW |
575 | /* Now encode the bytes using a slightly tweaked base-64 encoding. Read |
576 | * bytes into the accumulator and write out characters while there's | |
577 | * enough material. | |
578 | */ | |
579 | for (i = 0; i < TOKENRANDSZ; i++) { | |
9da480be MW |
580 | a = (a << 8) | tokenbuf[tokenptr++]; b += 8; |
581 | while (b >= 6) { | |
582 | b -= 6; | |
583 | *p++ = tokmap[(a >> b) & 0x3f]; | |
584 | } | |
585 | } | |
c3794524 MW |
586 | |
587 | /* If there's anything left in the accumulator then flush it out. */ | |
9da480be MW |
588 | if (b) |
589 | *p++ = tokmap[(a << (6 - b)) & 0x3f]; | |
c3794524 MW |
590 | |
591 | /* Null-terminate the token. */ | |
9da480be MW |
592 | *p++ = 0; |
593 | } | |
594 | ||
c3794524 MW |
595 | /* Notification that a line has been received from the client. Parse it, |
596 | * find out about the connection it's referring to, apply the relevant | |
597 | * policy rules, and produce a response. This is where almost everything | |
598 | * interesting happens. | |
599 | */ | |
9da480be MW |
600 | static void client_line(char *line, size_t len, void *p) |
601 | { | |
602 | struct client *c = p; | |
603 | const char *q; | |
604 | struct passwd *pw = 0; | |
605 | const struct policy *pol; | |
606 | dstr d = DSTR_INIT; | |
607 | struct policy upol = POLICY_INIT(A_LIMIT); | |
608 | struct policy_file pf; | |
609 | char buf[16]; | |
610 | int i; | |
611 | ||
c3794524 | 612 | /* If the connection has closed, then tidy stuff away. */ |
9da480be MW |
613 | c->q.s[L].port = c->q.s[R].port = 0; |
614 | if (!line) { | |
615 | disconnect_client(c); | |
616 | return; | |
617 | } | |
618 | ||
4f8fdcc1 MW |
619 | /* Client activity, so update the timer. */ |
620 | reset_client_timer(c, 1); | |
621 | ||
c3794524 MW |
622 | /* See if the policy file has changed since we last looked. If so, try to |
623 | * read the new version. | |
624 | */ | |
9da480be MW |
625 | if (fwatch_update(&polfw, "yaid.policy")) { |
626 | logmsg(0, LOG_INFO, "reload master policy file `%s'", "yaid.policy"); | |
627 | load_policy_file("yaid.policy", &policy); | |
628 | } | |
629 | ||
c3794524 | 630 | /* Read the local and remote port numbers into the query structure. */ |
9da480be MW |
631 | q = line; |
632 | if (unum(&q, &c->q.s[L].port, 1, 65535)) goto bad; | |
633 | skipws(&q); if (*q != ',') goto bad; q++; | |
634 | if (unum(&q, &c->q.s[R].port, 1, 65535)) goto bad; | |
635 | skipws(&q); if (*q) goto bad; | |
636 | ||
c3794524 | 637 | /* Identify the connection. Act on the result. */ |
9da480be MW |
638 | identify(&c->q); |
639 | switch (c->q.resp) { | |
c3794524 | 640 | |
9da480be | 641 | case R_UID: |
c3794524 MW |
642 | /* We found a user. Track down the user's password entry, because |
643 | * we'll want that later. Most of the processing for this case is | |
644 | * below. | |
645 | */ | |
9da480be MW |
646 | if ((pw = getpwuid(c->q.u.uid)) == 0) { |
647 | logmsg(&c->q, LOG_ERR, "no passwd entry for user %d", c->q.u.uid); | |
648 | reply_error(c, E_NOUSER); | |
649 | return; | |
650 | } | |
651 | break; | |
c3794524 | 652 | |
9da480be | 653 | case R_NAT: |
c3794524 MW |
654 | /* We've acted as a NAT for this connection. Proxy the query through |
655 | * to the actal client host. | |
656 | */ | |
9da480be MW |
657 | proxy_query(c); |
658 | return; | |
c3794524 | 659 | |
9da480be | 660 | case R_ERROR: |
c3794524 MW |
661 | /* We failed to identify the connection for some reason. We should |
662 | * already have logged an error, so there's not much to do here. | |
663 | */ | |
9da480be MW |
664 | reply_error(c, c->q.u.error); |
665 | return; | |
c3794524 | 666 | |
9da480be | 667 | default: |
c3794524 | 668 | /* Something happened that we don't understand. */ |
9da480be MW |
669 | abort(); |
670 | } | |
671 | ||
c3794524 | 672 | /* Search the table of policy rules to find a match. */ |
9da480be MW |
673 | for (i = 0; i < DA_LEN(&policy); i++) { |
674 | pol = &DA(&policy)[i]; | |
675 | if (!match_policy(pol, &c->q)) continue; | |
c3794524 MW |
676 | |
677 | /* If this is something simple, then apply the resulting policy rule. */ | |
678 | if (pol->act.act != A_USER) goto match; | |
679 | ||
680 | /* The global policy has decided to let the user have a say, so we must | |
681 | * parse the user file. | |
682 | */ | |
9da480be MW |
683 | DRESET(&d); |
684 | dstr_putf(&d, "%s/.yaid.policy", pw->pw_dir); | |
685 | if (open_policy_file(&pf, d.buf, "user policy file", &c->q)) | |
686 | continue; | |
687 | while (!read_policy_file(&pf)) { | |
c3794524 MW |
688 | |
689 | /* Give up after 100 lines. If the user's policy is that complicated, | |
690 | * something's gone very wrong. Or there's too much commentary or | |
691 | * something. | |
692 | */ | |
9da480be MW |
693 | if (pf.lno > 100) { |
694 | logmsg(&c->q, LOG_ERR, "%s:%d: user policy file too long", | |
695 | pf.name, pf.lno); | |
696 | break; | |
697 | } | |
c3794524 MW |
698 | |
699 | /* If this isn't a match, go around for the next rule. */ | |
9da480be | 700 | if (!match_policy(&pf.p, &c->q)) continue; |
c3794524 MW |
701 | |
702 | /* Check that the user is allowed to request this action. If not, see | |
703 | * if there's a more acceptable action later on. | |
704 | */ | |
9da480be MW |
705 | if (!(pol->act.u.user & (1 << pf.p.act.act))) { |
706 | logmsg(&c->q, LOG_ERR, | |
707 | "%s:%d: user action forbidden by global policy", | |
708 | pf.name, pf.lno); | |
709 | continue; | |
710 | } | |
c3794524 MW |
711 | |
712 | /* We've found a match, so grab it, close the file, and say we're | |
713 | * done. | |
714 | */ | |
9da480be MW |
715 | upol = pf.p; pol = &upol; |
716 | init_policy(&pf.p); | |
717 | close_policy_file(&pf); | |
c3794524 | 718 | DDESTROY(&d); |
9da480be MW |
719 | goto match; |
720 | } | |
721 | close_policy_file(&pf); | |
c3794524 | 722 | DDESTROY(&d); |
9da480be | 723 | } |
c3794524 MW |
724 | |
725 | /* No match: apply the built-in default policy. */ | |
9da480be MW |
726 | pol = &default_policy; |
727 | ||
728 | match: | |
9da480be | 729 | switch (pol->act.act) { |
c3794524 | 730 | |
9da480be | 731 | case A_NAME: |
c3794524 | 732 | /* Report the actual user's name. */ |
9da480be | 733 | logmsg(&c->q, LOG_INFO, "user `%s' (%d)", pw->pw_name, c->q.u.uid); |
c809f908 | 734 | reply(c, "USERID", "UNIX", pw->pw_name); |
9da480be | 735 | break; |
c3794524 | 736 | |
9da480be | 737 | case A_TOKEN: |
c3794524 | 738 | /* Report an arbitrary token which we can look up in our log file. */ |
9da480be MW |
739 | user_token(buf); |
740 | logmsg(&c->q, LOG_INFO, "user `%s' (%d); token = %s", | |
741 | pw->pw_name, c->q.u.uid, buf); | |
c809f908 | 742 | reply(c, "USERID", "OTHER", buf); |
9da480be | 743 | break; |
c3794524 | 744 | |
9da480be | 745 | case A_DENY: |
c3794524 | 746 | /* Deny that there's anyone there at all. */ |
9da480be MW |
747 | logmsg(&c->q, LOG_INFO, "user `%s' (%d); denying", |
748 | pw->pw_name, c->q.u.uid); | |
749 | break; | |
c3794524 | 750 | |
9da480be | 751 | case A_HIDE: |
c3794524 | 752 | /* Report the user as being hidden. */ |
9da480be MW |
753 | logmsg(&c->q, LOG_INFO, "user `%s' (%d); hiding", |
754 | pw->pw_name, c->q.u.uid); | |
755 | reply_error(c, E_HIDDEN); | |
756 | break; | |
c3794524 | 757 | |
9da480be | 758 | case A_LIE: |
c3794524 | 759 | /* Tell an egregious lie about who the user is. */ |
9da480be MW |
760 | logmsg(&c->q, LOG_INFO, "user `%s' (%d); lie = `%s'", |
761 | pw->pw_name, c->q.u.uid, pol->act.u.lie); | |
c809f908 | 762 | reply(c, "USERID", "UNIX", pol->act.u.lie); |
9da480be | 763 | break; |
c3794524 | 764 | |
9da480be | 765 | default: |
c3794524 | 766 | /* Something has gone very wrong. */ |
9da480be MW |
767 | abort(); |
768 | } | |
769 | ||
c3794524 | 770 | /* All done. */ |
9da480be MW |
771 | free_policy(&upol); |
772 | return; | |
773 | ||
774 | bad: | |
775 | logmsg(&c->q, LOG_ERR, "failed to parse query from client"); | |
776 | disconnect_client(c); | |
777 | } | |
778 | ||
c3794524 | 779 | /* Notification that a new client has connected. Prepare to read a query. */ |
9da480be MW |
780 | static void accept_client(int fd, unsigned mode, void *p) |
781 | { | |
782 | struct listen *l = p; | |
783 | struct client *c; | |
784 | struct sockaddr_storage ssr, ssl; | |
785 | size_t ssz = sizeof(ssr); | |
786 | int sk; | |
787 | ||
c3794524 | 788 | /* Accept the new connection. */ |
9da480be MW |
789 | if ((sk = accept(fd, (struct sockaddr *)&ssr, &ssz)) < 0) { |
790 | if (errno != EAGAIN && errno == EWOULDBLOCK) { | |
791 | logmsg(0, LOG_ERR, "failed to accept incoming %s connection: %s", | |
bf4d9761 | 792 | l->ao->name, strerror(errno)); |
9da480be MW |
793 | } |
794 | return; | |
795 | } | |
95df134c | 796 | if (fix_up_socket(sk, "incoming client")) { close(sk); return; } |
9da480be | 797 | |
c3794524 | 798 | /* Build a client block and fill it in. */ |
9da480be MW |
799 | c = xmalloc(sizeof(*c)); |
800 | c->l = l; | |
bf4d9761 | 801 | c->q.ao = l->ao; |
c3794524 MW |
802 | |
803 | /* Collect the local and remote addresses. */ | |
bf4d9761 | 804 | l->ao->sockaddr_to_addr(&ssr, &c->q.s[R].addr); |
9da480be MW |
805 | ssz = sizeof(ssl); |
806 | if (getsockname(sk, (struct sockaddr *)&ssl, &ssz)) { | |
807 | logmsg(0, LOG_ERR, | |
808 | "failed to read local address for incoming %s connection: %s", | |
bf4d9761 | 809 | l->ao->name, strerror(errno)); |
9da480be MW |
810 | close(sk); |
811 | xfree(c); | |
812 | return; | |
813 | } | |
bf4d9761 | 814 | l->ao->sockaddr_to_addr(&ssl, &c->q.s[L].addr); |
9da480be MW |
815 | c->q.s[L].port = c->q.s[R].port = 0; |
816 | ||
c3794524 | 817 | /* Set stuff up for reading the query and sending responses. */ |
9da480be MW |
818 | selbuf_init(&c->b, &sel, sk, client_line, c); |
819 | selbuf_setsize(&c->b, 1024); | |
4f8fdcc1 | 820 | reset_client_timer(c, 0); |
9da480be MW |
821 | c->fd = sk; |
822 | c->px = 0; | |
823 | init_writebuf(&c->wb, sk, done_client_write, c); | |
824 | } | |
825 | ||
c3794524 MW |
826 | /*----- Main code ---------------------------------------------------------*/ |
827 | ||
828 | /* Set up a listening socket for the address family described by AO, | |
829 | * listening on PORT. | |
830 | */ | |
bf4d9761 | 831 | static int make_listening_socket(const struct addrops *ao, int port) |
9da480be MW |
832 | { |
833 | int fd; | |
bf4d9761 MW |
834 | int yes = 1; |
835 | struct socket s; | |
9da480be MW |
836 | struct sockaddr_storage ss; |
837 | struct listen *l; | |
838 | size_t ssz; | |
839 | ||
c3794524 | 840 | /* Make the socket. */ |
bf4d9761 | 841 | if ((fd = socket(ao->af, SOCK_STREAM, 0)) < 0) { |
a20696ca | 842 | if (errno == EAFNOSUPPORT) return (-1); |
9da480be | 843 | die(1, "failed to create %s listening socket: %s", |
bf4d9761 | 844 | ao->name, strerror(errno)); |
9da480be | 845 | } |
c3794524 MW |
846 | |
847 | /* Build the appropriate local address. */ | |
bf4d9761 MW |
848 | s.addr = *ao->any; |
849 | s.port = port; | |
850 | ao->socket_to_sockaddr(&s, &ss, &ssz); | |
c3794524 MW |
851 | |
852 | /* Perform any initialization specific to the address type. */ | |
bf4d9761 MW |
853 | if (ao->init_listen_socket(fd)) { |
854 | die(1, "failed to initialize %s listening socket: %s", | |
855 | ao->name, strerror(errno)); | |
856 | } | |
c3794524 MW |
857 | |
858 | /* Bind to the address. */ | |
859 | setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)); | |
bf4d9761 MW |
860 | if (bind(fd, (struct sockaddr *)&ss, ssz)) { |
861 | die(1, "failed to bind %s listening socket: %s", | |
862 | ao->name, strerror(errno)); | |
9da480be | 863 | } |
c3794524 MW |
864 | |
865 | /* Avoid unpleasant race conditions. */ | |
bf4d9761 | 866 | if (fdflags(fd, O_NONBLOCK, O_NONBLOCK, 0, 0)) { |
9da480be | 867 | die(1, "failed to set %s listening socket nonblocking: %s", |
bf4d9761 | 868 | ao->name, strerror(errno)); |
9da480be | 869 | } |
c3794524 MW |
870 | |
871 | /* Prepare to listen. */ | |
9da480be | 872 | if (listen(fd, 5)) |
bf4d9761 | 873 | die(1, "failed to listen for %s: %s", ao->name, strerror(errno)); |
9da480be | 874 | |
c3794524 | 875 | /* Make a record of all of this. */ |
9da480be | 876 | l = xmalloc(sizeof(*l)); |
bf4d9761 | 877 | l->ao = ao; |
9da480be MW |
878 | sel_initfile(&sel, &l->f, fd, SEL_READ, accept_client, l); |
879 | sel_addfile(&l->f); | |
880 | ||
c3794524 | 881 | /* Done. */ |
a20696ca | 882 | return (0); |
9da480be MW |
883 | } |
884 | ||
885 | int main(int argc, char *argv[]) | |
886 | { | |
887 | int port = 113; | |
bf4d9761 MW |
888 | const struct addrops *ao; |
889 | int any = 0; | |
9da480be MW |
890 | |
891 | ego(argv[0]); | |
892 | ||
893 | fwatch_init(&polfw, "yaid.policy"); | |
b093b41d | 894 | init_sys(); |
9da480be MW |
895 | if (load_policy_file("yaid.policy", &policy)) |
896 | exit(1); | |
897 | { int i; | |
898 | for (i = 0; i < DA_LEN(&policy); i++) | |
899 | print_policy(&DA(&policy)[i]); | |
900 | } | |
901 | ||
902 | if ((randfd = open("/dev/urandom", O_RDONLY)) < 0) { | |
903 | die(1, "failed to open `/dev/urandom' for reading: %s", | |
904 | strerror(errno)); | |
905 | } | |
906 | ||
9da480be | 907 | sel_init(&sel); |
bf4d9761 MW |
908 | for (ao = addroptab; ao->name; ao++) |
909 | if (!make_listening_socket(ao, port)) any = 1; | |
910 | if (!any) | |
a20696ca | 911 | die(1, "no IP protocols supported"); |
9da480be MW |
912 | |
913 | for (;;) | |
914 | if (sel_select(&sel)) die(1, "select failed: %s", strerror(errno)); | |
915 | ||
916 | return (0); | |
917 | } | |
918 | ||
919 | /*----- That's all, folks -------------------------------------------------*/ |