1#include "cache.h"
2#include "pkt-line.h"
3#include <signal.h>
4#include <sys/wait.h>
5#include <sys/socket.h>
6#include <sys/time.h>
7#include <netdb.h>
8#include <netinet/in.h>
9#include <arpa/inet.h>
10#include <syslog.h>
11
12static int log_syslog;
13static int verbose;
14
15static const char daemon_usage[] =
16"git-daemon [--verbose] [--syslog] [--inetd | --port=n] [--export-all]\n"
17" [--timeout=n] [--init-timeout=n] [directory...]";
18
19/* List of acceptable pathname prefixes */
20static char **ok_paths = NULL;
21
22/* If this is set, git-daemon-export-ok is not required */
23static int export_all_trees = 0;
24
25/* Timeout, and initial timeout */
26static unsigned int timeout = 0;
27static unsigned int init_timeout = 0;
28
29static void logreport(int priority, const char *err, va_list params)
30{
31 /* We should do a single write so that it is atomic and output
32 * of several processes do not get intermingled. */
33 char buf[1024];
34 int buflen;
35 int maxlen, msglen;
36
37 /* sizeof(buf) should be big enough for "[pid] \n" */
38 buflen = snprintf(buf, sizeof(buf), "[%ld] ", (long) getpid());
39
40 maxlen = sizeof(buf) - buflen - 1; /* -1 for our own LF */
41 msglen = vsnprintf(buf + buflen, maxlen, err, params);
42
43 if (log_syslog) {
44 syslog(priority, "%s", buf);
45 return;
46 }
47
48 /* maxlen counted our own LF but also counts space given to
49 * vsnprintf for the terminating NUL. We want to make sure that
50 * we have space for our own LF and NUL after the "meat" of the
51 * message, so truncate it at maxlen - 1.
52 */
53 if (msglen > maxlen - 1)
54 msglen = maxlen - 1;
55 else if (msglen < 0)
56 msglen = 0; /* Protect against weird return values. */
57 buflen += msglen;
58
59 buf[buflen++] = '\n';
60 buf[buflen] = '\0';
61
62 write(2, buf, buflen);
63}
64
65static void logerror(const char *err, ...)
66{
67 va_list params;
68 va_start(params, err);
69 logreport(LOG_ERR, err, params);
70 va_end(params);
71}
72
73static void loginfo(const char *err, ...)
74{
75 va_list params;
76 if (!verbose)
77 return;
78 va_start(params, err);
79 logreport(LOG_INFO, err, params);
80 va_end(params);
81}
82
83static int path_ok(const char *dir)
84{
85 const char *p = dir;
86 char **pp;
87 int sl, ndot;
88
89 /* The pathname here should be an absolute path. */
90 if ( *p++ != '/' )
91 return 0;
92
93 sl = 1; ndot = 0;
94
95 for (;;) {
96 if ( *p == '.' ) {
97 ndot++;
98 } else if ( *p == '\0' ) {
99 /* Reject "." and ".." at the end of the path */
100 if ( sl && ndot > 0 && ndot < 3 )
101 return 0;
102
103 /* Otherwise OK */
104 break;
105 } else if ( *p == '/' ) {
106 /* Refuse "", "." or ".." */
107 if ( sl && ndot < 3 )
108 return 0;
109 sl = 1;
110 ndot = 0;
111 } else {
112 sl = ndot = 0;
113 }
114 p++;
115 }
116
117 if ( ok_paths && *ok_paths ) {
118 int ok = 0;
119 int dirlen = strlen(dir);
120
121 for ( pp = ok_paths ; *pp ; pp++ ) {
122 int len = strlen(*pp);
123 if ( len <= dirlen &&
124 !strncmp(*pp, dir, len) &&
125 (dir[len] == '/' || dir[len] == '\0') ) {
126 ok = 1;
127 break;
128 }
129 }
130
131 if ( !ok )
132 return 0; /* Path not in whitelist */
133 }
134
135 return 1; /* Path acceptable */
136}
137
138static int set_dir(const char *dir)
139{
140 if (!path_ok(dir)) {
141 errno = EACCES;
142 return -1;
143 }
144
145 if ( chdir(dir) )
146 return -1;
147
148 /*
149 * Security on the cheap.
150 *
151 * We want a readable HEAD, usable "objects" directory, and
152 * a "git-daemon-export-ok" flag that says that the other side
153 * is ok with us doing this.
154 */
155 if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
156 errno = EACCES;
157 return -1;
158 }
159
160 if (access("objects/", X_OK) || access("HEAD", R_OK)) {
161 errno = EINVAL;
162 return -1;
163 }
164
165 /* If all this passed, we're OK */
166 return 0;
167}
168
169static int upload(char *dir)
170{
171 /* Try paths in this order */
172 static const char *paths[] = { "%s", "%s/.git", "%s.git", "%s.git/.git", NULL };
173 const char **pp;
174 /* Enough for the longest path above including final null */
175 int buflen = strlen(dir)+10;
176 char *dirbuf = xmalloc(buflen);
177 /* Timeout as string */
178 char timeout_buf[64];
179
180 loginfo("Request for '%s'", dir);
181
182 for ( pp = paths ; *pp ; pp++ ) {
183 snprintf(dirbuf, buflen, *pp, dir);
184 if ( !set_dir(dirbuf) )
185 break;
186 }
187
188 if ( !*pp ) {
189 logerror("Cannot set directory '%s': %s", dir, strerror(errno));
190 return -1;
191 }
192
193 /*
194 * We'll ignore SIGTERM from now on, we have a
195 * good client.
196 */
197 signal(SIGTERM, SIG_IGN);
198
199 snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
200
201 /* git-upload-pack only ever reads stuff, so this is safe */
202 execlp("git-upload-pack", "git-upload-pack", "--strict", timeout_buf, ".", NULL);
203 return -1;
204}
205
206static int execute(void)
207{
208 static char line[1000];
209 int len;
210
211 alarm(init_timeout ? init_timeout : timeout);
212 len = packet_read_line(0, line, sizeof(line));
213 alarm(0);
214
215 if (len && line[len-1] == '\n')
216 line[--len] = 0;
217
218 if (!strncmp("git-upload-pack /", line, 17))
219 return upload(line+16);
220
221 logerror("Protocol error: '%s'", line);
222 return -1;
223}
224
225
226/*
227 * We count spawned/reaped separately, just to avoid any
228 * races when updating them from signals. The SIGCHLD handler
229 * will only update children_reaped, and the fork logic will
230 * only update children_spawned.
231 *
232 * MAX_CHILDREN should be a power-of-two to make the modulus
233 * operation cheap. It should also be at least twice
234 * the maximum number of connections we will ever allow.
235 */
236#define MAX_CHILDREN 128
237
238static int max_connections = 25;
239
240/* These are updated by the signal handler */
241static volatile unsigned int children_reaped = 0;
242static pid_t dead_child[MAX_CHILDREN];
243
244/* These are updated by the main loop */
245static unsigned int children_spawned = 0;
246static unsigned int children_deleted = 0;
247
248static struct child {
249 pid_t pid;
250 int addrlen;
251 struct sockaddr_storage address;
252} live_child[MAX_CHILDREN];
253
254static void add_child(int idx, pid_t pid, struct sockaddr *addr, int addrlen)
255{
256 live_child[idx].pid = pid;
257 live_child[idx].addrlen = addrlen;
258 memcpy(&live_child[idx].address, addr, addrlen);
259}
260
261/*
262 * Walk from "deleted" to "spawned", and remove child "pid".
263 *
264 * We move everything up by one, since the new "deleted" will
265 * be one higher.
266 */
267static void remove_child(pid_t pid, unsigned deleted, unsigned spawned)
268{
269 struct child n;
270
271 deleted %= MAX_CHILDREN;
272 spawned %= MAX_CHILDREN;
273 if (live_child[deleted].pid == pid) {
274 live_child[deleted].pid = -1;
275 return;
276 }
277 n = live_child[deleted];
278 for (;;) {
279 struct child m;
280 deleted = (deleted + 1) % MAX_CHILDREN;
281 if (deleted == spawned)
282 die("could not find dead child %d\n", pid);
283 m = live_child[deleted];
284 live_child[deleted] = n;
285 if (m.pid == pid)
286 return;
287 n = m;
288 }
289}
290
291/*
292 * This gets called if the number of connections grows
293 * past "max_connections".
294 *
295 * We _should_ start off by searching for connections
296 * from the same IP, and if there is some address wth
297 * multiple connections, we should kill that first.
298 *
299 * As it is, we just "randomly" kill 25% of the connections,
300 * and our pseudo-random generator sucks too. I have no
301 * shame.
302 *
303 * Really, this is just a place-holder for a _real_ algorithm.
304 */
305static void kill_some_children(int signo, unsigned start, unsigned stop)
306{
307 start %= MAX_CHILDREN;
308 stop %= MAX_CHILDREN;
309 while (start != stop) {
310 if (!(start & 3))
311 kill(live_child[start].pid, signo);
312 start = (start + 1) % MAX_CHILDREN;
313 }
314}
315
316static void check_max_connections(void)
317{
318 for (;;) {
319 int active;
320 unsigned spawned, reaped, deleted;
321
322 spawned = children_spawned;
323 reaped = children_reaped;
324 deleted = children_deleted;
325
326 while (deleted < reaped) {
327 pid_t pid = dead_child[deleted % MAX_CHILDREN];
328 remove_child(pid, deleted, spawned);
329 deleted++;
330 }
331 children_deleted = deleted;
332
333 active = spawned - deleted;
334 if (active <= max_connections)
335 break;
336
337 /* Kill some unstarted connections with SIGTERM */
338 kill_some_children(SIGTERM, deleted, spawned);
339 if (active <= max_connections << 1)
340 break;
341
342 /* If the SIGTERM thing isn't helping use SIGKILL */
343 kill_some_children(SIGKILL, deleted, spawned);
344 sleep(1);
345 }
346}
347
348static void handle(int incoming, struct sockaddr *addr, int addrlen)
349{
350 pid_t pid = fork();
351 char addrbuf[256] = "";
352 int port = -1;
353
354 if (pid) {
355 unsigned idx;
356
357 close(incoming);
358 if (pid < 0)
359 return;
360
361 idx = children_spawned % MAX_CHILDREN;
362 children_spawned++;
363 add_child(idx, pid, addr, addrlen);
364
365 check_max_connections();
366 return;
367 }
368
369 dup2(incoming, 0);
370 dup2(incoming, 1);
371 close(incoming);
372
373 if (addr->sa_family == AF_INET) {
374 struct sockaddr_in *sin_addr = (void *) addr;
375 inet_ntop(AF_INET, &sin_addr->sin_addr, addrbuf, sizeof(addrbuf));
376 port = sin_addr->sin_port;
377
378 } else if (addr->sa_family == AF_INET6) {
379 struct sockaddr_in6 *sin6_addr = (void *) addr;
380
381 char *buf = addrbuf;
382 *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
383 inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(addrbuf) - 1);
384 strcat(buf, "]");
385
386 port = sin6_addr->sin6_port;
387 }
388 loginfo("Connection from %s:%d", addrbuf, port);
389
390 exit(execute());
391}
392
393static void child_handler(int signo)
394{
395 for (;;) {
396 int status;
397 pid_t pid = waitpid(-1, &status, WNOHANG);
398
399 if (pid > 0) {
400 unsigned reaped = children_reaped;
401 dead_child[reaped % MAX_CHILDREN] = pid;
402 children_reaped = reaped + 1;
403 /* XXX: Custom logging, since we don't wanna getpid() */
404 if (verbose) {
405 char *dead = "";
406 if (!WIFEXITED(status) || WEXITSTATUS(status) > 0)
407 dead = " (with error)";
408 if (log_syslog)
409 syslog(LOG_INFO, "[%d] Disconnected%s", pid, dead);
410 else
411 fprintf(stderr, "[%d] Disconnected%s\n", pid, dead);
412 }
413 continue;
414 }
415 break;
416 }
417}
418
419static int serve(int port)
420{
421 struct addrinfo hints, *ai0, *ai;
422 int gai;
423 int socknum = 0, *socklist = NULL;
424 int maxfd = -1;
425 fd_set fds_init, fds;
426 char pbuf[NI_MAXSERV];
427
428 signal(SIGCHLD, child_handler);
429
430 sprintf(pbuf, "%d", port);
431 memset(&hints, 0, sizeof(hints));
432 hints.ai_family = AF_UNSPEC;
433 hints.ai_socktype = SOCK_STREAM;
434 hints.ai_protocol = IPPROTO_TCP;
435 hints.ai_flags = AI_PASSIVE;
436
437 gai = getaddrinfo(NULL, pbuf, &hints, &ai0);
438 if (gai)
439 die("getaddrinfo() failed: %s\n", gai_strerror(gai));
440
441 FD_ZERO(&fds_init);
442
443 for (ai = ai0; ai; ai = ai->ai_next) {
444 int sockfd;
445 int *newlist;
446
447 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
448 if (sockfd < 0)
449 continue;
450 if (sockfd >= FD_SETSIZE) {
451 error("too large socket descriptor.");
452 close(sockfd);
453 continue;
454 }
455
456#ifdef IPV6_V6ONLY
457 if (ai->ai_family == AF_INET6) {
458 int on = 1;
459 setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
460 &on, sizeof(on));
461 /* Note: error is not fatal */
462 }
463#endif
464
465 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
466 close(sockfd);
467 continue; /* not fatal */
468 }
469 if (listen(sockfd, 5) < 0) {
470 close(sockfd);
471 continue; /* not fatal */
472 }
473
474 newlist = realloc(socklist, sizeof(int) * (socknum + 1));
475 if (!newlist)
476 die("memory allocation failed: %s", strerror(errno));
477
478 socklist = newlist;
479 socklist[socknum++] = sockfd;
480
481 FD_SET(sockfd, &fds_init);
482 if (maxfd < sockfd)
483 maxfd = sockfd;
484 }
485
486 freeaddrinfo(ai0);
487
488 if (socknum == 0)
489 die("unable to allocate any listen sockets on port %u", port);
490
491 for (;;) {
492 int i;
493 fds = fds_init;
494
495 if (select(maxfd + 1, &fds, NULL, NULL, NULL) < 0) {
496 if (errno != EINTR) {
497 error("select failed, resuming: %s",
498 strerror(errno));
499 sleep(1);
500 }
501 continue;
502 }
503
504 for (i = 0; i < socknum; i++) {
505 int sockfd = socklist[i];
506
507 if (FD_ISSET(sockfd, &fds)) {
508 struct sockaddr_storage ss;
509 int sslen = sizeof(ss);
510 int incoming = accept(sockfd, (struct sockaddr *)&ss, &sslen);
511 if (incoming < 0) {
512 switch (errno) {
513 case EAGAIN:
514 case EINTR:
515 case ECONNABORTED:
516 continue;
517 default:
518 die("accept returned %s", strerror(errno));
519 }
520 }
521 handle(incoming, (struct sockaddr *)&ss, sslen);
522 }
523 }
524 }
525}
526
527int main(int argc, char **argv)
528{
529 int port = DEFAULT_GIT_PORT;
530 int inetd_mode = 0;
531 int i;
532
533 for (i = 1; i < argc; i++) {
534 char *arg = argv[i];
535
536 if (!strncmp(arg, "--port=", 7)) {
537 char *end;
538 unsigned long n;
539 n = strtoul(arg+7, &end, 0);
540 if (arg[7] && !*end) {
541 port = n;
542 continue;
543 }
544 }
545 if (!strcmp(arg, "--inetd")) {
546 inetd_mode = 1;
547 continue;
548 }
549 if (!strcmp(arg, "--verbose")) {
550 verbose = 1;
551 continue;
552 }
553 if (!strcmp(arg, "--syslog")) {
554 log_syslog = 1;
555 openlog("git-daemon", 0, LOG_DAEMON);
556 continue;
557 }
558 if (!strcmp(arg, "--export-all")) {
559 export_all_trees = 1;
560 continue;
561 }
562 if (!strncmp(arg, "--timeout=", 10)) {
563 timeout = atoi(arg+10);
564 }
565 if (!strncmp(arg, "--init-timeout=", 15)) {
566 init_timeout = atoi(arg+15);
567 }
568 if (!strcmp(arg, "--")) {
569 ok_paths = &argv[i+1];
570 break;
571 } else if (arg[0] != '-') {
572 ok_paths = &argv[i];
573 break;
574 }
575
576 usage(daemon_usage);
577 }
578
579 if (inetd_mode) {
580 fclose(stderr); //FIXME: workaround
581 return execute();
582 }
583
584 return serve(port);
585}