X-Git-Url: https://git.octo.it/?a=blobdiff_plain;f=daemon.c;h=08e3b15225691ac0077ed222552ec09875f56d51;hb=750a09a7de63c92868cff41a3151eac320c77fa0;hp=e6fbab6bc9d6b0c2358841b0ca3b821b8a68189b;hpb=eaa9491955ef645bd2d3ca989f17bb80b9896d23;p=git.git diff --git a/daemon.c b/daemon.c index e6fbab6b..08e3b152 100644 --- a/daemon.c +++ b/daemon.c @@ -3,28 +3,143 @@ #include #include #include +#include +#include #include +#include +#include -static const char daemon_usage[] = "git-daemon [--inetd | --port=n]"; +static int log_syslog; +static int verbose; -/* We don't actually do anything about this yet */ -static int max_connections = 10; +static const char daemon_usage[] = "git-daemon [--verbose] [--syslog] [--inetd | --port=n] [--export-all] [directory...]"; -/* - * We count spawned/reaped separately, just to avoid any - * races when updating them from signals. The SIGCHLD handler - * will only update children_reaped, and the fork logic will - * only update children_spawned. - */ -static unsigned int children_spawned = 0; -static unsigned int children_reaped = 0; +/* List of acceptable pathname prefixes */ +static char **ok_paths = NULL; + +/* If this is set, git-daemon-export-ok is not required */ +static int export_all_trees = 0; -static int upload(char *dir, int dirlen) + +static void logreport(int priority, const char *err, va_list params) { - if (chdir(dir) < 0) + /* We should do a single write so that it is atomic and output + * of several processes do not get intermingled. */ + char buf[1024]; + int buflen; + int maxlen, msglen; + + /* sizeof(buf) should be big enough for "[pid] \n" */ + buflen = snprintf(buf, sizeof(buf), "[%ld] ", (long) getpid()); + + maxlen = sizeof(buf) - buflen - 1; /* -1 for our own LF */ + msglen = vsnprintf(buf + buflen, maxlen, err, params); + + if (log_syslog) { + syslog(priority, "%s", buf); + return; + } + + /* maxlen counted our own LF but also counts space given to + * vsnprintf for the terminating NUL. We want to make sure that + * we have space for our own LF and NUL after the "meat" of the + * message, so truncate it at maxlen - 1. + */ + if (msglen > maxlen - 1) + msglen = maxlen - 1; + else if (msglen < 0) + msglen = 0; /* Protect against weird return values. */ + buflen += msglen; + + buf[buflen++] = '\n'; + buf[buflen] = '\0'; + + write(2, buf, buflen); +} + +static void logerror(const char *err, ...) +{ + va_list params; + va_start(params, err); + logreport(LOG_ERR, err, params); + va_end(params); +} + +static void loginfo(const char *err, ...) +{ + va_list params; + if (!verbose) + return; + va_start(params, err); + logreport(LOG_INFO, err, params); + va_end(params); +} + +static int path_ok(const char *dir) +{ + const char *p = dir; + char **pp; + int sl, ndot; + + /* The pathname here should be an absolute path. */ + if ( *p++ != '/' ) + return 0; + + sl = 1; ndot = 0; + + for (;;) { + if ( *p == '.' ) { + ndot++; + } else if ( *p == '\0' ) { + /* Reject "." and ".." at the end of the path */ + if ( sl && ndot > 0 && ndot < 3 ) + return 0; + + /* Otherwise OK */ + break; + } else if ( *p == '/' ) { + /* Refuse "", "." or ".." */ + if ( sl && ndot < 3 ) + return 0; + sl = 1; + ndot = 0; + } else { + sl = ndot = 0; + } + p++; + } + + if ( ok_paths && *ok_paths ) { + int ok = 0; + int dirlen = strlen(dir); + + for ( pp = ok_paths ; *pp ; pp++ ) { + int len = strlen(*pp); + if ( len <= dirlen && + !strncmp(*pp, dir, len) && + (dir[len] == '/' || dir[len] == '\0') ) { + ok = 1; + break; + } + } + + if ( !ok ) + return 0; /* Path not in whitelist */ + } + + return 1; /* Path acceptable */ +} + +static int set_dir(const char *dir) +{ + if (!path_ok(dir)) { + errno = EACCES; return -1; - chdir(".git"); + } + if ( chdir(dir) ) + return -1; + /* * Security on the cheap. * @@ -32,10 +147,47 @@ static int upload(char *dir, int dirlen) * a "git-daemon-export-ok" flag that says that the other side * is ok with us doing this. */ - if (access("git-daemon-export-ok", F_OK) || - access("objects/00", X_OK) || - access("HEAD", R_OK)) + if (!export_all_trees && access("git-daemon-export-ok", F_OK)) { + errno = EACCES; + return -1; + } + + if (access("objects/", X_OK) || access("HEAD", R_OK)) { + errno = EINVAL; + return -1; + } + + /* If all this passed, we're OK */ + return 0; +} + +static int upload(char *dir) +{ + /* Try paths in this order */ + static const char *paths[] = { "%s", "%s/.git", "%s.git", "%s.git/.git", NULL }; + const char **pp; + /* Enough for the longest path above including final null */ + int buflen = strlen(dir)+10; + char *dirbuf = xmalloc(buflen); + + loginfo("Request for '%s'", dir); + + for ( pp = paths ; *pp ; pp++ ) { + snprintf(dirbuf, buflen, *pp, dir); + if ( !set_dir(dirbuf) ) + break; + } + + if ( !*pp ) { + logerror("Cannot set directory '%s': %s", dir, strerror(errno)); return -1; + } + + /* + * We'll ignore SIGTERM from now on, we have a + * good client. + */ + signal(SIGTERM, SIG_IGN); /* git-upload-pack only ever reads stuff, so this is safe */ execlp("git-upload-pack", "git-upload-pack", ".", NULL); @@ -53,46 +205,200 @@ static int execute(void) line[--len] = 0; if (!strncmp("git-upload-pack /", line, 17)) - return upload(line + 16, len - 16); + return upload(line+16); - fprintf(stderr, "got bad connection '%s'\n", line); + logerror("Protocol error: '%s'", line); return -1; } -static void handle(int incoming, struct sockaddr_in *addr, int addrlen) + +/* + * We count spawned/reaped separately, just to avoid any + * races when updating them from signals. The SIGCHLD handler + * will only update children_reaped, and the fork logic will + * only update children_spawned. + * + * MAX_CHILDREN should be a power-of-two to make the modulus + * operation cheap. It should also be at least twice + * the maximum number of connections we will ever allow. + */ +#define MAX_CHILDREN 128 + +static int max_connections = 25; + +/* These are updated by the signal handler */ +static volatile unsigned int children_reaped = 0; +static pid_t dead_child[MAX_CHILDREN]; + +/* These are updated by the main loop */ +static unsigned int children_spawned = 0; +static unsigned int children_deleted = 0; + +static struct child { + pid_t pid; + int addrlen; + struct sockaddr_storage address; +} live_child[MAX_CHILDREN]; + +static void add_child(int idx, pid_t pid, struct sockaddr *addr, int addrlen) +{ + live_child[idx].pid = pid; + live_child[idx].addrlen = addrlen; + memcpy(&live_child[idx].address, addr, addrlen); +} + +/* + * Walk from "deleted" to "spawned", and remove child "pid". + * + * We move everything up by one, since the new "deleted" will + * be one higher. + */ +static void remove_child(pid_t pid, unsigned deleted, unsigned spawned) +{ + struct child n; + + deleted %= MAX_CHILDREN; + spawned %= MAX_CHILDREN; + if (live_child[deleted].pid == pid) { + live_child[deleted].pid = -1; + return; + } + n = live_child[deleted]; + for (;;) { + struct child m; + deleted = (deleted + 1) % MAX_CHILDREN; + if (deleted == spawned) + die("could not find dead child %d\n", pid); + m = live_child[deleted]; + live_child[deleted] = n; + if (m.pid == pid) + return; + n = m; + } +} + +/* + * This gets called if the number of connections grows + * past "max_connections". + * + * We _should_ start off by searching for connections + * from the same IP, and if there is some address wth + * multiple connections, we should kill that first. + * + * As it is, we just "randomly" kill 25% of the connections, + * and our pseudo-random generator sucks too. I have no + * shame. + * + * Really, this is just a place-holder for a _real_ algorithm. + */ +static void kill_some_children(int signo, unsigned start, unsigned stop) +{ + start %= MAX_CHILDREN; + stop %= MAX_CHILDREN; + while (start != stop) { + if (!(start & 3)) + kill(live_child[start].pid, signo); + start = (start + 1) % MAX_CHILDREN; + } +} + +static void check_max_connections(void) +{ + for (;;) { + int active; + unsigned spawned, reaped, deleted; + + spawned = children_spawned; + reaped = children_reaped; + deleted = children_deleted; + + while (deleted < reaped) { + pid_t pid = dead_child[deleted % MAX_CHILDREN]; + remove_child(pid, deleted, spawned); + deleted++; + } + children_deleted = deleted; + + active = spawned - deleted; + if (active <= max_connections) + break; + + /* Kill some unstarted connections with SIGTERM */ + kill_some_children(SIGTERM, deleted, spawned); + if (active <= max_connections << 1) + break; + + /* If the SIGTERM thing isn't helping use SIGKILL */ + kill_some_children(SIGKILL, deleted, spawned); + sleep(1); + } +} + +static void handle(int incoming, struct sockaddr *addr, int addrlen) { pid_t pid = fork(); + char addrbuf[256] = ""; + int port = -1; if (pid) { - int active; + unsigned idx; close(incoming); if (pid < 0) return; - active = ++children_spawned - children_reaped; - if (active > max_connections) { - /* - * Fixme! This is where you'd have to do something to - * limit the number of children. Like killing off random - * ones, or at least the ones that haven't even gotten - * started yet. - */ - } + idx = children_spawned % MAX_CHILDREN; + children_spawned++; + add_child(idx, pid, addr, addrlen); + + check_max_connections(); return; } dup2(incoming, 0); dup2(incoming, 1); close(incoming); + + if (addr->sa_family == AF_INET) { + struct sockaddr_in *sin_addr = (void *) addr; + inet_ntop(AF_INET, &sin_addr->sin_addr, addrbuf, sizeof(addrbuf)); + port = sin_addr->sin_port; + + } else if (addr->sa_family == AF_INET6) { + struct sockaddr_in6 *sin6_addr = (void *) addr; + + char *buf = addrbuf; + *buf++ = '['; *buf = '\0'; /* stpcpy() is cool */ + inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(addrbuf) - 1); + strcat(buf, "]"); + + port = sin6_addr->sin6_port; + } + loginfo("Connection from %s:%d", addrbuf, port); + exit(execute()); } static void child_handler(int signo) { for (;;) { - if (waitpid(-1, NULL, WNOHANG) > 0) { - children_reaped++; + int status; + pid_t pid = waitpid(-1, &status, WNOHANG); + + if (pid > 0) { + unsigned reaped = children_reaped; + dead_child[reaped % MAX_CHILDREN] = pid; + children_reaped = reaped + 1; + /* XXX: Custom logging, since we don't wanna getpid() */ + if (verbose) { + char *dead = ""; + if (!WIFEXITED(status) || WEXITSTATUS(status) > 0) + dead = " (with error)"; + if (log_syslog) + syslog(LOG_INFO, "[%d] Disconnected%s", pid, dead); + else + fprintf(stderr, "[%d] Disconnected%s\n", pid, dead); + } continue; } break; @@ -101,37 +407,109 @@ static void child_handler(int signo) static int serve(int port) { - int sockfd; - struct sockaddr_in addr; + struct addrinfo hints, *ai0, *ai; + int gai; + int socknum = 0, *socklist = NULL; + int maxfd = -1; + fd_set fds_init, fds; + char pbuf[NI_MAXSERV]; signal(SIGCHLD, child_handler); - sockfd = socket(PF_INET, SOCK_STREAM, IPPROTO_IP); - if (sockfd < 0) - die("unable to open socket (%s)", strerror(errno)); - memset(&addr, 0, sizeof(addr)); - addr.sin_port = htons(port); - addr.sin_family = AF_INET; - if (bind(sockfd, (void *)&addr, sizeof(addr)) < 0) - die("unable to bind to port %d (%s)", port, strerror(errno)); - if (listen(sockfd, 5) < 0) - die("unable to listen to port %d (%s)", port, strerror(errno)); + + sprintf(pbuf, "%d", port); + memset(&hints, 0, sizeof(hints)); + hints.ai_family = AF_UNSPEC; + hints.ai_socktype = SOCK_STREAM; + hints.ai_protocol = IPPROTO_TCP; + hints.ai_flags = AI_PASSIVE; + + gai = getaddrinfo(NULL, pbuf, &hints, &ai0); + if (gai) + die("getaddrinfo() failed: %s\n", gai_strerror(gai)); + + FD_ZERO(&fds_init); + + for (ai = ai0; ai; ai = ai->ai_next) { + int sockfd; + int *newlist; + + sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); + if (sockfd < 0) + continue; + if (sockfd >= FD_SETSIZE) { + error("too large socket descriptor."); + close(sockfd); + continue; + } + +#ifdef IPV6_V6ONLY + if (ai->ai_family == AF_INET6) { + int on = 1; + setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY, + &on, sizeof(on)); + /* Note: error is not fatal */ + } +#endif + + if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) { + close(sockfd); + continue; /* not fatal */ + } + if (listen(sockfd, 5) < 0) { + close(sockfd); + continue; /* not fatal */ + } + + newlist = realloc(socklist, sizeof(int) * (socknum + 1)); + if (!newlist) + die("memory allocation failed: %s", strerror(errno)); + + socklist = newlist; + socklist[socknum++] = sockfd; + + FD_SET(sockfd, &fds_init); + if (maxfd < sockfd) + maxfd = sockfd; + } + + freeaddrinfo(ai0); + + if (socknum == 0) + die("unable to allocate any listen sockets on port %u", port); for (;;) { - struct sockaddr_in in; - socklen_t addrlen = sizeof(in); - int incoming = accept(sockfd, (void *)&in, &addrlen); - - if (incoming < 0) { - switch (errno) { - case EAGAIN: - case EINTR: - case ECONNABORTED: - continue; - default: - die("accept returned %s", strerror(errno)); + int i; + fds = fds_init; + + if (select(maxfd + 1, &fds, NULL, NULL, NULL) < 0) { + if (errno != EINTR) { + error("select failed, resuming: %s", + strerror(errno)); + sleep(1); + } + continue; + } + + for (i = 0; i < socknum; i++) { + int sockfd = socklist[i]; + + if (FD_ISSET(sockfd, &fds)) { + struct sockaddr_storage ss; + int sslen = sizeof(ss); + int incoming = accept(sockfd, (struct sockaddr *)&ss, &sslen); + if (incoming < 0) { + switch (errno) { + case EAGAIN: + case EINTR: + case ECONNABORTED: + continue; + default: + die("accept returned %s", strerror(errno)); + } + } + handle(incoming, (struct sockaddr *)&ss, sslen); } } - handle(incoming, &in, addrlen); } } @@ -153,17 +531,38 @@ int main(int argc, char **argv) continue; } } - if (!strcmp(arg, "--inetd")) { inetd_mode = 1; continue; } + if (!strcmp(arg, "--verbose")) { + verbose = 1; + continue; + } + if (!strcmp(arg, "--syslog")) { + log_syslog = 1; + openlog("git-daemon", 0, LOG_DAEMON); + continue; + } + if (!strcmp(arg, "--export-all")) { + export_all_trees = 1; + continue; + } + if (!strcmp(arg, "--")) { + ok_paths = &argv[i+1]; + break; + } else if (arg[0] != '-') { + ok_paths = &argv[i]; + break; + } usage(daemon_usage); } - if (inetd_mode) + if (inetd_mode) { + fclose(stderr); //FIXME: workaround return execute(); + } return serve(port); }