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