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[] = "git-daemon [--verbose] [--syslog] [--inetd | --port=n] [--export-all] [directory...]";
16
17/* List of acceptable pathname prefixes */
18static char **ok_paths = NULL;
19
20/* If this is set, git-daemon-export-ok is not required */
21static int export_all_trees = 0;
22
23
24static void logreport(int priority, const char *err, va_list params)
25{
26 /* We should do a single write so that it is atomic and output
27 * of several processes do not get intermingled. */
28 char buf[1024];
29 int buflen;
30 int maxlen, msglen;
31
32 /* sizeof(buf) should be big enough for "[pid] \n" */
33 buflen = snprintf(buf, sizeof(buf), "[%ld] ", (long) getpid());
34
35 maxlen = sizeof(buf) - buflen - 1; /* -1 for our own LF */
36 msglen = vsnprintf(buf + buflen, maxlen, err, params);
37
38 if (log_syslog) {
39 syslog(priority, "%s", buf);
40 return;
41 }
42
43 /* maxlen counted our own LF but also counts space given to
44 * vsnprintf for the terminating NUL. We want to make sure that
45 * we have space for our own LF and NUL after the "meat" of the
46 * message, so truncate it at maxlen - 1.
47 */
48 if (msglen > maxlen - 1)
49 msglen = maxlen - 1;
50 else if (msglen < 0)
51 msglen = 0; /* Protect against weird return values. */
52 buflen += msglen;
53
54 buf[buflen++] = '\n';
55 buf[buflen] = '\0';
56
57 write(2, buf, buflen);
58}
59
60void logerror(const char *err, ...)
61{
62 va_list params;
63 va_start(params, err);
64 logreport(LOG_ERR, err, params);
65 va_end(params);
66}
67
68void loginfo(const char *err, ...)
69{
70 va_list params;
71 if (!verbose)
72 return;
73 va_start(params, err);
74 logreport(LOG_INFO, err, params);
75 va_end(params);
76}
77
78static int path_ok(const char *dir)
79{
80 const char *p = dir;
81 char **pp;
82 int sl = 1, ndot = 0;
83
84 for (;;) {
85 if ( *p == '.' ) {
86 ndot++;
87 } else if ( *p == '/' || *p == '\0' ) {
88 if ( sl && ndot > 0 && ndot < 3 )
89 return 0; /* . or .. in path */
90 sl = 1;
91 if ( *p == '\0' )
92 break; /* End of string and all is good */
93 } else {
94 sl = ndot = 0;
95 }
96 p++;
97 }
98
99 if ( ok_paths && *ok_paths ) {
100 int ok = 0;
101 int dirlen = strlen(dir); /* read_packet_line can return embedded \0 */
102
103 for ( pp = ok_paths ; *pp ; pp++ ) {
104 int len = strlen(*pp);
105 if ( len <= dirlen &&
106 !strncmp(*pp, dir, len) &&
107 (dir[len] == '/' || dir[len] == '\0') ) {
108 ok = 1;
109 break;
110 }
111 }
112
113 if ( !ok )
114 return 0; /* Path not in whitelist */
115 }
116
117 return 1; /* Path acceptable */
118}
119
120static int upload(char *dir, int dirlen)
121{
122 loginfo("Request for '%s'", dir);
123
124 if (!path_ok(dir)) {
125 logerror("Forbidden directory: %s\n", dir);
126 return -1;
127 }
128
129 if (chdir(dir) < 0) {
130 logerror("Cannot chdir('%s'): %s", dir, strerror(errno));
131 return -1;
132 }
133
134 /*
135 * Security on the cheap.
136 *
137 * We want a readable HEAD, usable "objects" directory, and
138 * a "git-daemon-export-ok" flag that says that the other side
139 * is ok with us doing this.
140 */
141 if ((!export_all_trees && access("git-daemon-export-ok", F_OK)) ||
142 access("objects/00", X_OK) ||
143 access("HEAD", R_OK)) {
144 logerror("Not a valid git-daemon-enabled repository: '%s'", dir);
145 return -1;
146 }
147
148 /*
149 * We'll ignore SIGTERM from now on, we have a
150 * good client.
151 */
152 signal(SIGTERM, SIG_IGN);
153
154 /* git-upload-pack only ever reads stuff, so this is safe */
155 execlp("git-upload-pack", "git-upload-pack", ".", NULL);
156 return -1;
157}
158
159static int execute(void)
160{
161 static char line[1000];
162 int len;
163
164 len = packet_read_line(0, line, sizeof(line));
165
166 if (len && line[len-1] == '\n')
167 line[--len] = 0;
168
169 if (!strncmp("git-upload-pack /", line, 17))
170 return upload(line + 16, len - 16);
171
172 logerror("Protocol error: '%s'", line);
173 return -1;
174}
175
176
177/*
178 * We count spawned/reaped separately, just to avoid any
179 * races when updating them from signals. The SIGCHLD handler
180 * will only update children_reaped, and the fork logic will
181 * only update children_spawned.
182 *
183 * MAX_CHILDREN should be a power-of-two to make the modulus
184 * operation cheap. It should also be at least twice
185 * the maximum number of connections we will ever allow.
186 */
187#define MAX_CHILDREN 128
188
189static int max_connections = 25;
190
191/* These are updated by the signal handler */
192static volatile unsigned int children_reaped = 0;
193static pid_t dead_child[MAX_CHILDREN];
194
195/* These are updated by the main loop */
196static unsigned int children_spawned = 0;
197static unsigned int children_deleted = 0;
198
199static struct child {
200 pid_t pid;
201 int addrlen;
202 struct sockaddr_storage address;
203} live_child[MAX_CHILDREN];
204
205static void add_child(int idx, pid_t pid, struct sockaddr *addr, int addrlen)
206{
207 live_child[idx].pid = pid;
208 live_child[idx].addrlen = addrlen;
209 memcpy(&live_child[idx].address, addr, addrlen);
210}
211
212/*
213 * Walk from "deleted" to "spawned", and remove child "pid".
214 *
215 * We move everything up by one, since the new "deleted" will
216 * be one higher.
217 */
218static void remove_child(pid_t pid, unsigned deleted, unsigned spawned)
219{
220 struct child n;
221
222 deleted %= MAX_CHILDREN;
223 spawned %= MAX_CHILDREN;
224 if (live_child[deleted].pid == pid) {
225 live_child[deleted].pid = -1;
226 return;
227 }
228 n = live_child[deleted];
229 for (;;) {
230 struct child m;
231 deleted = (deleted + 1) % MAX_CHILDREN;
232 if (deleted == spawned)
233 die("could not find dead child %d\n", pid);
234 m = live_child[deleted];
235 live_child[deleted] = n;
236 if (m.pid == pid)
237 return;
238 n = m;
239 }
240}
241
242/*
243 * This gets called if the number of connections grows
244 * past "max_connections".
245 *
246 * We _should_ start off by searching for connections
247 * from the same IP, and if there is some address wth
248 * multiple connections, we should kill that first.
249 *
250 * As it is, we just "randomly" kill 25% of the connections,
251 * and our pseudo-random generator sucks too. I have no
252 * shame.
253 *
254 * Really, this is just a place-holder for a _real_ algorithm.
255 */
256static void kill_some_children(int signo, unsigned start, unsigned stop)
257{
258 start %= MAX_CHILDREN;
259 stop %= MAX_CHILDREN;
260 while (start != stop) {
261 if (!(start & 3))
262 kill(live_child[start].pid, signo);
263 start = (start + 1) % MAX_CHILDREN;
264 }
265}
266
267static void check_max_connections(void)
268{
269 for (;;) {
270 int active;
271 unsigned spawned, reaped, deleted;
272
273 spawned = children_spawned;
274 reaped = children_reaped;
275 deleted = children_deleted;
276
277 while (deleted < reaped) {
278 pid_t pid = dead_child[deleted % MAX_CHILDREN];
279 remove_child(pid, deleted, spawned);
280 deleted++;
281 }
282 children_deleted = deleted;
283
284 active = spawned - deleted;
285 if (active <= max_connections)
286 break;
287
288 /* Kill some unstarted connections with SIGTERM */
289 kill_some_children(SIGTERM, deleted, spawned);
290 if (active <= max_connections << 1)
291 break;
292
293 /* If the SIGTERM thing isn't helping use SIGKILL */
294 kill_some_children(SIGKILL, deleted, spawned);
295 sleep(1);
296 }
297}
298
299static void handle(int incoming, struct sockaddr *addr, int addrlen)
300{
301 pid_t pid = fork();
302 char addrbuf[256] = "";
303 int port = -1;
304
305 if (pid) {
306 unsigned idx;
307
308 close(incoming);
309 if (pid < 0)
310 return;
311
312 idx = children_spawned % MAX_CHILDREN;
313 children_spawned++;
314 add_child(idx, pid, addr, addrlen);
315
316 check_max_connections();
317 return;
318 }
319
320 dup2(incoming, 0);
321 dup2(incoming, 1);
322 close(incoming);
323
324 if (addr->sa_family == AF_INET) {
325 struct sockaddr_in *sin_addr = (void *) addr;
326 inet_ntop(AF_INET, &sin_addr->sin_addr, addrbuf, sizeof(addrbuf));
327 port = sin_addr->sin_port;
328
329 } else if (addr->sa_family == AF_INET6) {
330 struct sockaddr_in6 *sin6_addr = (void *) addr;
331
332 char *buf = addrbuf;
333 *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
334 inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(addrbuf) - 1);
335 strcat(buf, "]");
336
337 port = sin6_addr->sin6_port;
338 }
339 loginfo("Connection from %s:%d", addrbuf, port);
340
341 exit(execute());
342}
343
344static void child_handler(int signo)
345{
346 for (;;) {
347 int status;
348 pid_t pid = waitpid(-1, &status, WNOHANG);
349
350 if (pid > 0) {
351 unsigned reaped = children_reaped;
352 dead_child[reaped % MAX_CHILDREN] = pid;
353 children_reaped = reaped + 1;
354 /* XXX: Custom logging, since we don't wanna getpid() */
355 if (verbose) {
356 char *dead = "";
357 if (!WIFEXITED(status) || WEXITSTATUS(status) > 0)
358 dead = " (with error)";
359 if (log_syslog)
360 syslog(LOG_INFO, "[%d] Disconnected%s", pid, dead);
361 else
362 fprintf(stderr, "[%d] Disconnected%s\n", pid, dead);
363 }
364 continue;
365 }
366 break;
367 }
368}
369
370static int serve(int port)
371{
372 struct addrinfo hints, *ai0, *ai;
373 int gai;
374 int socknum = 0, *socklist = NULL;
375 int maxfd = -1;
376 fd_set fds_init, fds;
377 char pbuf[NI_MAXSERV];
378
379 signal(SIGCHLD, child_handler);
380
381 sprintf(pbuf, "%d", port);
382 memset(&hints, 0, sizeof(hints));
383 hints.ai_family = AF_UNSPEC;
384 hints.ai_socktype = SOCK_STREAM;
385 hints.ai_protocol = IPPROTO_TCP;
386 hints.ai_flags = AI_PASSIVE;
387
388 gai = getaddrinfo(NULL, pbuf, &hints, &ai0);
389 if (gai)
390 die("getaddrinfo() failed: %s\n", gai_strerror(gai));
391
392 FD_ZERO(&fds_init);
393
394 for (ai = ai0; ai; ai = ai->ai_next) {
395 int sockfd;
396 int *newlist;
397
398 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
399 if (sockfd < 0)
400 continue;
401 if (sockfd >= FD_SETSIZE) {
402 error("too large socket descriptor.");
403 close(sockfd);
404 continue;
405 }
406
407#ifdef IPV6_V6ONLY
408 if (ai->ai_family == AF_INET6) {
409 int on = 1;
410 setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
411 &on, sizeof(on));
412 /* Note: error is not fatal */
413 }
414#endif
415
416 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
417 close(sockfd);
418 continue; /* not fatal */
419 }
420 if (listen(sockfd, 5) < 0) {
421 close(sockfd);
422 continue; /* not fatal */
423 }
424
425 newlist = realloc(socklist, sizeof(int) * (socknum + 1));
426 if (!newlist)
427 die("memory allocation failed: %s", strerror(errno));
428
429 socklist = newlist;
430 socklist[socknum++] = sockfd;
431
432 FD_SET(sockfd, &fds_init);
433 if (maxfd < sockfd)
434 maxfd = sockfd;
435 }
436
437 freeaddrinfo(ai0);
438
439 if (socknum == 0)
440 die("unable to allocate any listen sockets on port %u", port);
441
442 for (;;) {
443 int i;
444 fds = fds_init;
445
446 if (select(maxfd + 1, &fds, NULL, NULL, NULL) < 0) {
447 if (errno != EINTR) {
448 error("select failed, resuming: %s",
449 strerror(errno));
450 sleep(1);
451 }
452 continue;
453 }
454
455 for (i = 0; i < socknum; i++) {
456 int sockfd = socklist[i];
457
458 if (FD_ISSET(sockfd, &fds)) {
459 struct sockaddr_storage ss;
460 int sslen = sizeof(ss);
461 int incoming = accept(sockfd, (struct sockaddr *)&ss, &sslen);
462 if (incoming < 0) {
463 switch (errno) {
464 case EAGAIN:
465 case EINTR:
466 case ECONNABORTED:
467 continue;
468 default:
469 die("accept returned %s", strerror(errno));
470 }
471 }
472 handle(incoming, (struct sockaddr *)&ss, sslen);
473 }
474 }
475 }
476}
477
478int main(int argc, char **argv)
479{
480 int port = DEFAULT_GIT_PORT;
481 int inetd_mode = 0;
482 int i;
483
484 for (i = 1; i < argc; i++) {
485 char *arg = argv[i];
486
487 if (!strncmp(arg, "--port=", 7)) {
488 char *end;
489 unsigned long n;
490 n = strtoul(arg+7, &end, 0);
491 if (arg[7] && !*end) {
492 port = n;
493 continue;
494 }
495 }
496 if (!strcmp(arg, "--inetd")) {
497 inetd_mode = 1;
498 continue;
499 }
500 if (!strcmp(arg, "--verbose")) {
501 verbose = 1;
502 continue;
503 }
504 if (!strcmp(arg, "--syslog")) {
505 log_syslog = 1;
506 openlog("git-daemon", 0, LOG_DAEMON);
507 continue;
508 }
509 if (!strcmp(arg, "--export-all")) {
510 export_all_trees = 1;
511 continue;
512 }
513 if (!strcmp(arg, "--")) {
514 ok_paths = &argv[i+1];
515 break;
516 } else if (arg[0] != '-') {
517 ok_paths = &argv[i];
518 break;
519 }
520
521 usage(daemon_usage);
522 }
523
524 if (inetd_mode) {
525 fclose(stderr); //FIXME: workaround
526 return execute();
527 }
528
529 return serve(port);
530}