daemon: do not forbid user relative paths unconditionally under --base-path
[git/git.git] / daemon.c
CommitLineData
eaa94919
LT
1#include <signal.h>
2#include <sys/wait.h>
a87e8be2 3#include <sys/socket.h>
3cd6ecda 4#include <sys/time.h>
6573faff 5#include <sys/poll.h>
df076bdb 6#include <netdb.h>
a87e8be2 7#include <netinet/in.h>
f8ff0c06 8#include <arpa/inet.h>
9048fe1c 9#include <syslog.h>
979e32fa
RS
10#include "pkt-line.h"
11#include "cache.h"
77cb17e9 12#include "exec_cmd.h"
f8ff0c06 13
9048fe1c 14static int log_syslog;
f8ff0c06
PB
15static int verbose;
16
960deccb
PA
17static const char daemon_usage[] =
18"git-daemon [--verbose] [--syslog] [--inetd | --port=n] [--export-all]\n"
b21c31c9
PB
19" [--timeout=n] [--init-timeout=n] [--strict-paths]\n"
20" [--base-path=path] [directory...]";
4ae95682
PA
21
22/* List of acceptable pathname prefixes */
23static char **ok_paths = NULL;
4dbd1352 24static int strict_paths = 0;
4ae95682
PA
25
26/* If this is set, git-daemon-export-ok is not required */
27static int export_all_trees = 0;
f8ff0c06 28
b21c31c9
PB
29/* Take all paths relative to this one if non-NULL */
30static char *base_path = NULL;
31
960deccb
PA
32/* Timeout, and initial timeout */
33static unsigned int timeout = 0;
34static unsigned int init_timeout = 0;
f8ff0c06 35
9048fe1c 36static void logreport(int priority, const char *err, va_list params)
f8ff0c06
PB
37{
38 /* We should do a single write so that it is atomic and output
39 * of several processes do not get intermingled. */
40 char buf[1024];
41 int buflen;
42 int maxlen, msglen;
43
44 /* sizeof(buf) should be big enough for "[pid] \n" */
1bedd4ca 45 buflen = snprintf(buf, sizeof(buf), "[%ld] ", (long) getpid());
f8ff0c06
PB
46
47 maxlen = sizeof(buf) - buflen - 1; /* -1 for our own LF */
48 msglen = vsnprintf(buf + buflen, maxlen, err, params);
49
9048fe1c
PB
50 if (log_syslog) {
51 syslog(priority, "%s", buf);
52 return;
53 }
54
f8ff0c06
PB
55 /* maxlen counted our own LF but also counts space given to
56 * vsnprintf for the terminating NUL. We want to make sure that
57 * we have space for our own LF and NUL after the "meat" of the
58 * message, so truncate it at maxlen - 1.
59 */
60 if (msglen > maxlen - 1)
61 msglen = maxlen - 1;
62 else if (msglen < 0)
63 msglen = 0; /* Protect against weird return values. */
64 buflen += msglen;
65
66 buf[buflen++] = '\n';
67 buf[buflen] = '\0';
68
69 write(2, buf, buflen);
70}
71
cdda4745 72static void logerror(const char *err, ...)
f8ff0c06
PB
73{
74 va_list params;
75 va_start(params, err);
9048fe1c 76 logreport(LOG_ERR, err, params);
f8ff0c06
PB
77 va_end(params);
78}
79
cdda4745 80static void loginfo(const char *err, ...)
f8ff0c06
PB
81{
82 va_list params;
83 if (!verbose)
84 return;
85 va_start(params, err);
9048fe1c 86 logreport(LOG_INFO, err, params);
f8ff0c06
PB
87 va_end(params);
88}
a87e8be2 89
d79374c7
JH
90static int avoid_alias(char *p)
91{
92 int sl, ndot;
93
94 /*
95 * This resurrects the belts and suspenders paranoia check by HPA
96 * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
97 * does not do getcwd() based path canonicalizations.
98 *
99 * sl becomes true immediately after seeing '/' and continues to
100 * be true as long as dots continue after that without intervening
101 * non-dot character.
102 */
103 if (!p || (*p != '/' && *p != '~'))
104 return -1;
105 sl = 1; ndot = 0;
106 p++;
107
108 while (1) {
109 char ch = *p++;
110 if (sl) {
111 if (ch == '.')
112 ndot++;
113 else if (ch == '/') {
114 if (ndot < 3)
115 /* reject //, /./ and /../ */
116 return -1;
117 ndot = 0;
118 }
119 else if (ch == 0) {
120 if (0 < ndot && ndot < 3)
121 /* reject /.$ and /..$ */
122 return -1;
123 return 0;
124 }
125 else
126 sl = ndot = 0;
127 }
128 else if (ch == 0)
129 return 0;
130 else if (ch == '/') {
131 sl = 1;
132 ndot = 0;
133 }
134 }
135}
136
4dbd1352 137static char *path_ok(char *dir)
4ae95682 138{
d79374c7
JH
139 char *path;
140
141 if (avoid_alias(dir)) {
142 logerror("'%s': aliased", dir);
143 return NULL;
144 }
145
b21c31c9
PB
146 if (base_path) {
147 static char rpath[PATH_MAX];
363f24c9
JH
148 if (!strict_paths && *dir == '~')
149 ; /* allow user relative paths */
150 else if (*dir != '/') {
151 /* otherwise allow only absolute */
1fda3d55 152 logerror("'%s': Non-absolute path denied (base-path active)", dir);
b21c31c9
PB
153 return NULL;
154 }
363f24c9
JH
155 else {
156 snprintf(rpath, PATH_MAX, "%s%s", base_path, dir);
157 dir = rpath;
158 }
b21c31c9
PB
159 }
160
d79374c7 161 path = enter_repo(dir, strict_paths);
3e04c62d 162
4dbd1352
AE
163 if (!path) {
164 logerror("'%s': unable to chdir or not a git archive", dir);
165 return NULL;
4ae95682
PA
166 }
167
168 if ( ok_paths && *ok_paths ) {
ce335fe0 169 char **pp;
4dbd1352 170 int pathlen = strlen(path);
4ae95682 171
ce335fe0 172 /* The validation is done on the paths after enter_repo
d79374c7
JH
173 * appends optional {.git,.git/.git} and friends, but
174 * it does not use getcwd(). So if your /pub is
175 * a symlink to /mnt/pub, you can whitelist /pub and
176 * do not have to say /mnt/pub.
177 * Do not say /pub/.
ce335fe0 178 */
4ae95682
PA
179 for ( pp = ok_paths ; *pp ; pp++ ) {
180 int len = strlen(*pp);
ce335fe0
JH
181 if (len <= pathlen &&
182 !memcmp(*pp, path, len) &&
183 (path[len] == '\0' ||
184 (!strict_paths && path[len] == '/')))
185 return path;
4ae95682 186 }
4dbd1352
AE
187 }
188 else {
189 /* be backwards compatible */
190 if (!strict_paths)
191 return path;
4ae95682
PA
192 }
193
4dbd1352
AE
194 logerror("'%s': not in whitelist", path);
195 return NULL; /* Fallthrough. Deny by default */
4ae95682 196}
a87e8be2 197
4dbd1352 198static int upload(char *dir)
a87e8be2 199{
4dbd1352
AE
200 /* Timeout as string */
201 char timeout_buf[64];
202 const char *path;
203
204 loginfo("Request for '%s'", dir);
4ae95682 205
4dbd1352 206 if (!(path = path_ok(dir)))
a87e8be2 207 return -1;
47888f0f 208
a87e8be2
LT
209 /*
210 * Security on the cheap.
211 *
a935c397 212 * We want a readable HEAD, usable "objects" directory, and
a87e8be2
LT
213 * a "git-daemon-export-ok" flag that says that the other side
214 * is ok with us doing this.
4dbd1352
AE
215 *
216 * path_ok() uses enter_repo() and does whitelist checking.
217 * We only need to make sure the repository is exported.
a87e8be2 218 */
4dbd1352 219
3e04c62d 220 if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
4dbd1352 221 logerror("'%s': repository not exported.", path);
3e04c62d
PA
222 errno = EACCES;
223 return -1;
224 }
225
02d57da4
LT
226 /*
227 * We'll ignore SIGTERM from now on, we have a
228 * good client.
229 */
230 signal(SIGTERM, SIG_IGN);
231
960deccb
PA
232 snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
233
a87e8be2 234 /* git-upload-pack only ever reads stuff, so this is safe */
77cb17e9 235 execl_git_cmd("upload-pack", "--strict", timeout_buf, ".", NULL);
a87e8be2
LT
236 return -1;
237}
238
7d80694a 239static int execute(void)
a87e8be2 240{
7d80694a
LT
241 static char line[1000];
242 int len;
243
960deccb 244 alarm(init_timeout ? init_timeout : timeout);
7d80694a 245 len = packet_read_line(0, line, sizeof(line));
960deccb 246 alarm(0);
7d80694a
LT
247
248 if (len && line[len-1] == '\n')
249 line[--len] = 0;
250
4dbd1352 251 if (!strncmp("git-upload-pack ", line, 16))
3e04c62d 252 return upload(line+16);
a87e8be2 253
f8ff0c06 254 logerror("Protocol error: '%s'", line);
a87e8be2
LT
255 return -1;
256}
257
66e631de
LT
258
259/*
260 * We count spawned/reaped separately, just to avoid any
261 * races when updating them from signals. The SIGCHLD handler
262 * will only update children_reaped, and the fork logic will
263 * only update children_spawned.
264 *
265 * MAX_CHILDREN should be a power-of-two to make the modulus
266 * operation cheap. It should also be at least twice
267 * the maximum number of connections we will ever allow.
268 */
269#define MAX_CHILDREN 128
270
271static int max_connections = 25;
272
273/* These are updated by the signal handler */
274static volatile unsigned int children_reaped = 0;
4d8fa916 275static pid_t dead_child[MAX_CHILDREN];
66e631de
LT
276
277/* These are updated by the main loop */
278static unsigned int children_spawned = 0;
279static unsigned int children_deleted = 0;
280
4d8fa916 281static struct child {
66e631de 282 pid_t pid;
7fa09084 283 int addrlen;
df076bdb 284 struct sockaddr_storage address;
66e631de
LT
285} live_child[MAX_CHILDREN];
286
7fa09084 287static void add_child(int idx, pid_t pid, struct sockaddr *addr, int addrlen)
66e631de
LT
288{
289 live_child[idx].pid = pid;
290 live_child[idx].addrlen = addrlen;
df076bdb 291 memcpy(&live_child[idx].address, addr, addrlen);
66e631de
LT
292}
293
294/*
295 * Walk from "deleted" to "spawned", and remove child "pid".
296 *
297 * We move everything up by one, since the new "deleted" will
298 * be one higher.
299 */
300static void remove_child(pid_t pid, unsigned deleted, unsigned spawned)
301{
302 struct child n;
303
304 deleted %= MAX_CHILDREN;
305 spawned %= MAX_CHILDREN;
306 if (live_child[deleted].pid == pid) {
307 live_child[deleted].pid = -1;
308 return;
309 }
310 n = live_child[deleted];
311 for (;;) {
312 struct child m;
313 deleted = (deleted + 1) % MAX_CHILDREN;
314 if (deleted == spawned)
315 die("could not find dead child %d\n", pid);
316 m = live_child[deleted];
317 live_child[deleted] = n;
318 if (m.pid == pid)
319 return;
320 n = m;
321 }
322}
323
324/*
325 * This gets called if the number of connections grows
326 * past "max_connections".
327 *
328 * We _should_ start off by searching for connections
329 * from the same IP, and if there is some address wth
330 * multiple connections, we should kill that first.
331 *
332 * As it is, we just "randomly" kill 25% of the connections,
333 * and our pseudo-random generator sucks too. I have no
334 * shame.
335 *
336 * Really, this is just a place-holder for a _real_ algorithm.
337 */
02d57da4 338static void kill_some_children(int signo, unsigned start, unsigned stop)
66e631de
LT
339{
340 start %= MAX_CHILDREN;
341 stop %= MAX_CHILDREN;
342 while (start != stop) {
343 if (!(start & 3))
02d57da4 344 kill(live_child[start].pid, signo);
66e631de
LT
345 start = (start + 1) % MAX_CHILDREN;
346 }
347}
348
02d57da4 349static void check_max_connections(void)
a87e8be2 350{
02d57da4 351 for (;;) {
eaa94919 352 int active;
66e631de 353 unsigned spawned, reaped, deleted;
eaa94919 354
66e631de 355 spawned = children_spawned;
66e631de
LT
356 reaped = children_reaped;
357 deleted = children_deleted;
358
359 while (deleted < reaped) {
360 pid_t pid = dead_child[deleted % MAX_CHILDREN];
361 remove_child(pid, deleted, spawned);
362 deleted++;
363 }
364 children_deleted = deleted;
365
366 active = spawned - deleted;
02d57da4
LT
367 if (active <= max_connections)
368 break;
66e631de 369
02d57da4
LT
370 /* Kill some unstarted connections with SIGTERM */
371 kill_some_children(SIGTERM, deleted, spawned);
372 if (active <= max_connections << 1)
373 break;
374
375 /* If the SIGTERM thing isn't helping use SIGKILL */
376 kill_some_children(SIGKILL, deleted, spawned);
377 sleep(1);
378 }
379}
380
7fa09084 381static void handle(int incoming, struct sockaddr *addr, int addrlen)
02d57da4
LT
382{
383 pid_t pid = fork();
f8ff0c06
PB
384 char addrbuf[256] = "";
385 int port = -1;
02d57da4
LT
386
387 if (pid) {
388 unsigned idx;
389
390 close(incoming);
391 if (pid < 0)
392 return;
393
394 idx = children_spawned % MAX_CHILDREN;
395 children_spawned++;
396 add_child(idx, pid, addr, addrlen);
66e631de 397
02d57da4 398 check_max_connections();
a87e8be2
LT
399 return;
400 }
401
402 dup2(incoming, 0);
403 dup2(incoming, 1);
404 close(incoming);
f8ff0c06
PB
405
406 if (addr->sa_family == AF_INET) {
407 struct sockaddr_in *sin_addr = (void *) addr;
408 inet_ntop(AF_INET, &sin_addr->sin_addr, addrbuf, sizeof(addrbuf));
409 port = sin_addr->sin_port;
410
6573faff 411#ifndef NO_IPV6
f8ff0c06
PB
412 } else if (addr->sa_family == AF_INET6) {
413 struct sockaddr_in6 *sin6_addr = (void *) addr;
414
415 char *buf = addrbuf;
416 *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
417 inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(addrbuf) - 1);
418 strcat(buf, "]");
419
420 port = sin6_addr->sin6_port;
6573faff 421#endif
f8ff0c06 422 }
da38641d 423 loginfo("Connection from %s:%d", addrbuf, port);
f8ff0c06 424
7d80694a 425 exit(execute());
a87e8be2
LT
426}
427
eaa94919
LT
428static void child_handler(int signo)
429{
430 for (;;) {
9048fe1c
PB
431 int status;
432 pid_t pid = waitpid(-1, &status, WNOHANG);
66e631de
LT
433
434 if (pid > 0) {
435 unsigned reaped = children_reaped;
436 dead_child[reaped % MAX_CHILDREN] = pid;
437 children_reaped = reaped + 1;
f8ff0c06 438 /* XXX: Custom logging, since we don't wanna getpid() */
9048fe1c
PB
439 if (verbose) {
440 char *dead = "";
441 if (!WIFEXITED(status) || WEXITSTATUS(status) > 0)
442 dead = " (with error)";
443 if (log_syslog)
444 syslog(LOG_INFO, "[%d] Disconnected%s", pid, dead);
445 else
446 fprintf(stderr, "[%d] Disconnected%s\n", pid, dead);
447 }
eaa94919
LT
448 continue;
449 }
450 break;
451 }
452}
453
6573faff
PA
454#ifndef NO_IPV6
455
456static int socksetup(int port, int **socklist_p)
a87e8be2 457{
df076bdb
YH
458 int socknum = 0, *socklist = NULL;
459 int maxfd = -1;
df076bdb 460 char pbuf[NI_MAXSERV];
a87e8be2 461
6573faff
PA
462 struct addrinfo hints, *ai0, *ai;
463 int gai;
df076bdb
YH
464
465 sprintf(pbuf, "%d", port);
466 memset(&hints, 0, sizeof(hints));
467 hints.ai_family = AF_UNSPEC;
468 hints.ai_socktype = SOCK_STREAM;
469 hints.ai_protocol = IPPROTO_TCP;
470 hints.ai_flags = AI_PASSIVE;
471
472 gai = getaddrinfo(NULL, pbuf, &hints, &ai0);
473 if (gai)
474 die("getaddrinfo() failed: %s\n", gai_strerror(gai));
475
df076bdb
YH
476 for (ai = ai0; ai; ai = ai->ai_next) {
477 int sockfd;
478 int *newlist;
479
480 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
481 if (sockfd < 0)
482 continue;
483 if (sockfd >= FD_SETSIZE) {
484 error("too large socket descriptor.");
485 close(sockfd);
486 continue;
487 }
488
489#ifdef IPV6_V6ONLY
490 if (ai->ai_family == AF_INET6) {
491 int on = 1;
492 setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
493 &on, sizeof(on));
494 /* Note: error is not fatal */
495 }
496#endif
497
498 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
499 close(sockfd);
500 continue; /* not fatal */
501 }
502 if (listen(sockfd, 5) < 0) {
503 close(sockfd);
504 continue; /* not fatal */
505 }
506
507 newlist = realloc(socklist, sizeof(int) * (socknum + 1));
508 if (!newlist)
509 die("memory allocation failed: %s", strerror(errno));
510
511 socklist = newlist;
512 socklist[socknum++] = sockfd;
513
df076bdb
YH
514 if (maxfd < sockfd)
515 maxfd = sockfd;
516 }
517
518 freeaddrinfo(ai0);
519
6573faff
PA
520 *socklist_p = socklist;
521 return socknum;
522}
523
524#else /* NO_IPV6 */
525
526static int socksetup(int port, int **socklist_p)
527{
528 struct sockaddr_in sin;
529 int sockfd;
530
531 sockfd = socket(AF_INET, SOCK_STREAM, 0);
532 if (sockfd < 0)
533 return 0;
534
535 memset(&sin, 0, sizeof sin);
536 sin.sin_family = AF_INET;
537 sin.sin_addr.s_addr = htonl(INADDR_ANY);
538 sin.sin_port = htons(port);
539
540 if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
541 close(sockfd);
542 return 0;
543 }
a87e8be2 544
f35230fb
PS
545 if (listen(sockfd, 5) < 0) {
546 close(sockfd);
547 return 0;
548 }
549
1b4713fb 550 *socklist_p = xmalloc(sizeof(int));
6573faff 551 **socklist_p = sockfd;
f35230fb 552 return 1;
6573faff
PA
553}
554
555#endif
556
557static int service_loop(int socknum, int *socklist)
558{
559 struct pollfd *pfd;
560 int i;
561
1b4713fb 562 pfd = xcalloc(socknum, sizeof(struct pollfd));
6573faff
PA
563
564 for (i = 0; i < socknum; i++) {
565 pfd[i].fd = socklist[i];
566 pfd[i].events = POLLIN;
567 }
9220282a
PA
568
569 signal(SIGCHLD, child_handler);
a87e8be2
LT
570
571 for (;;) {
df076bdb 572 int i;
6573faff 573
7872e055 574 if (poll(pfd, socknum, -1) < 0) {
1eef0b33 575 if (errno != EINTR) {
6573faff 576 error("poll failed, resuming: %s",
1eef0b33
JH
577 strerror(errno));
578 sleep(1);
579 }
df076bdb
YH
580 continue;
581 }
582
583 for (i = 0; i < socknum; i++) {
6573faff 584 if (pfd[i].revents & POLLIN) {
df076bdb 585 struct sockaddr_storage ss;
7626e49e 586 unsigned int sslen = sizeof(ss);
6573faff 587 int incoming = accept(pfd[i].fd, (struct sockaddr *)&ss, &sslen);
df076bdb
YH
588 if (incoming < 0) {
589 switch (errno) {
590 case EAGAIN:
591 case EINTR:
592 case ECONNABORTED:
593 continue;
594 default:
595 die("accept returned %s", strerror(errno));
596 }
597 }
598 handle(incoming, (struct sockaddr *)&ss, sslen);
a87e8be2
LT
599 }
600 }
a87e8be2
LT
601 }
602}
603
6573faff
PA
604static int serve(int port)
605{
606 int socknum, *socklist;
4ae22d96 607
6573faff
PA
608 socknum = socksetup(port, &socklist);
609 if (socknum == 0)
610 die("unable to allocate any listen sockets on port %u", port);
4ae22d96 611
6573faff 612 return service_loop(socknum, socklist);
4ae22d96 613}
6573faff 614
a87e8be2
LT
615int main(int argc, char **argv)
616{
617 int port = DEFAULT_GIT_PORT;
e64e1b79 618 int inetd_mode = 0;
a87e8be2
LT
619 int i;
620
621 for (i = 1; i < argc; i++) {
622 char *arg = argv[i];
623
624 if (!strncmp(arg, "--port=", 7)) {
625 char *end;
626 unsigned long n;
627 n = strtoul(arg+7, &end, 0);
628 if (arg[7] && !*end) {
629 port = n;
630 continue;
631 }
632 }
e64e1b79
LT
633 if (!strcmp(arg, "--inetd")) {
634 inetd_mode = 1;
a8883288 635 log_syslog = 1;
e64e1b79
LT
636 continue;
637 }
f8ff0c06
PB
638 if (!strcmp(arg, "--verbose")) {
639 verbose = 1;
640 continue;
641 }
9048fe1c
PB
642 if (!strcmp(arg, "--syslog")) {
643 log_syslog = 1;
9048fe1c
PB
644 continue;
645 }
4ae95682
PA
646 if (!strcmp(arg, "--export-all")) {
647 export_all_trees = 1;
648 continue;
649 }
960deccb
PA
650 if (!strncmp(arg, "--timeout=", 10)) {
651 timeout = atoi(arg+10);
a8883288 652 continue;
960deccb 653 }
54e31a20 654 if (!strncmp(arg, "--init-timeout=", 15)) {
960deccb 655 init_timeout = atoi(arg+15);
a8883288 656 continue;
960deccb 657 }
4dbd1352
AE
658 if (!strcmp(arg, "--strict-paths")) {
659 strict_paths = 1;
660 continue;
661 }
b21c31c9
PB
662 if (!strncmp(arg, "--base-path=", 12)) {
663 base_path = arg+12;
664 continue;
665 }
4ae95682
PA
666 if (!strcmp(arg, "--")) {
667 ok_paths = &argv[i+1];
668 break;
669 } else if (arg[0] != '-') {
670 ok_paths = &argv[i];
671 break;
672 }
e64e1b79 673
a87e8be2
LT
674 usage(daemon_usage);
675 }
676
a8883288
AE
677 if (log_syslog)
678 openlog("git-daemon", 0, LOG_DAEMON);
679
4dbd1352
AE
680 if (strict_paths && (!ok_paths || !*ok_paths)) {
681 if (!inetd_mode)
682 die("git-daemon: option --strict-paths requires a whitelist");
683
684 logerror("option --strict-paths requires a whitelist");
685 exit (1);
686 }
687
7c3693f1
LD
688 if (inetd_mode) {
689 fclose(stderr); //FIXME: workaround
e64e1b79 690 return execute();
7c3693f1 691 }
bce8230d
AE
692
693 return serve(port);
a87e8be2 694}