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-rw-r--r--daemon.c759
1 files changed, 759 insertions, 0 deletions
diff --git a/daemon.c b/daemon.c
new file mode 100644
index 0000000000..2f03f99d2d
--- /dev/null
+++ b/daemon.c
@@ -0,0 +1,759 @@
+#include <signal.h>
+#include <sys/wait.h>
+#include <sys/socket.h>
+#include <sys/time.h>
+#include <sys/poll.h>
+#include <netdb.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <syslog.h>
+#include "pkt-line.h"
+#include "cache.h"
+#include "exec_cmd.h"
+
+static int log_syslog;
+static int verbose;
+static int reuseaddr;
+
+static const char daemon_usage[] =
+"git-daemon [--verbose] [--syslog] [--inetd | --port=n] [--export-all]\n"
+" [--timeout=n] [--init-timeout=n] [--strict-paths]\n"
+" [--base-path=path] [--user-path | --user-path=path]\n"
+" [--reuseaddr] [directory...]";
+
+/* List of acceptable pathname prefixes */
+static char **ok_paths = NULL;
+static int strict_paths = 0;
+
+/* If this is set, git-daemon-export-ok is not required */
+static int export_all_trees = 0;
+
+/* Take all paths relative to this one if non-NULL */
+static char *base_path = NULL;
+
+/* If defined, ~user notation is allowed and the string is inserted
+ * after ~user/. E.g. a request to git://host/~alice/frotz would
+ * go to /home/alice/pub_git/frotz with --user-path=pub_git.
+ */
+static char *user_path = NULL;
+
+/* Timeout, and initial timeout */
+static unsigned int timeout = 0;
+static unsigned int init_timeout = 0;
+
+static void logreport(int priority, const char *err, va_list params)
+{
+ /* 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 avoid_alias(char *p)
+{
+ int sl, ndot;
+
+ /*
+ * This resurrects the belts and suspenders paranoia check by HPA
+ * done in <435560F7.4080006@zytor.com> thread, now enter_repo()
+ * does not do getcwd() based path canonicalizations.
+ *
+ * sl becomes true immediately after seeing '/' and continues to
+ * be true as long as dots continue after that without intervening
+ * non-dot character.
+ */
+ if (!p || (*p != '/' && *p != '~'))
+ return -1;
+ sl = 1; ndot = 0;
+ p++;
+
+ while (1) {
+ char ch = *p++;
+ if (sl) {
+ if (ch == '.')
+ ndot++;
+ else if (ch == '/') {
+ if (ndot < 3)
+ /* reject //, /./ and /../ */
+ return -1;
+ ndot = 0;
+ }
+ else if (ch == 0) {
+ if (0 < ndot && ndot < 3)
+ /* reject /.$ and /..$ */
+ return -1;
+ return 0;
+ }
+ else
+ sl = ndot = 0;
+ }
+ else if (ch == 0)
+ return 0;
+ else if (ch == '/') {
+ sl = 1;
+ ndot = 0;
+ }
+ }
+}
+
+static char *path_ok(char *dir)
+{
+ static char rpath[PATH_MAX];
+ char *path;
+
+ if (avoid_alias(dir)) {
+ logerror("'%s': aliased", dir);
+ return NULL;
+ }
+
+ if (*dir == '~') {
+ if (!user_path) {
+ logerror("'%s': User-path not allowed", dir);
+ return NULL;
+ }
+ if (*user_path) {
+ /* Got either "~alice" or "~alice/foo";
+ * rewrite them to "~alice/%s" or
+ * "~alice/%s/foo".
+ */
+ int namlen, restlen = strlen(dir);
+ char *slash = strchr(dir, '/');
+ if (!slash)
+ slash = dir + restlen;
+ namlen = slash - dir;
+ restlen -= namlen;
+ loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
+ snprintf(rpath, PATH_MAX, "%.*s/%s%.*s",
+ namlen, dir, user_path, restlen, slash);
+ dir = rpath;
+ }
+ }
+ else if (base_path) {
+ if (*dir != '/') {
+ /* Allow only absolute */
+ logerror("'%s': Non-absolute path denied (base-path active)", dir);
+ return NULL;
+ }
+ else {
+ snprintf(rpath, PATH_MAX, "%s%s", base_path, dir);
+ dir = rpath;
+ }
+ }
+
+ path = enter_repo(dir, strict_paths);
+
+ if (!path) {
+ logerror("'%s': unable to chdir or not a git archive", dir);
+ return NULL;
+ }
+
+ if ( ok_paths && *ok_paths ) {
+ char **pp;
+ int pathlen = strlen(path);
+
+ /* The validation is done on the paths after enter_repo
+ * appends optional {.git,.git/.git} and friends, but
+ * it does not use getcwd(). So if your /pub is
+ * a symlink to /mnt/pub, you can whitelist /pub and
+ * do not have to say /mnt/pub.
+ * Do not say /pub/.
+ */
+ for ( pp = ok_paths ; *pp ; pp++ ) {
+ int len = strlen(*pp);
+ if (len <= pathlen &&
+ !memcmp(*pp, path, len) &&
+ (path[len] == '\0' ||
+ (!strict_paths && path[len] == '/')))
+ return path;
+ }
+ }
+ else {
+ /* be backwards compatible */
+ if (!strict_paths)
+ return path;
+ }
+
+ logerror("'%s': not in whitelist", path);
+ return NULL; /* Fallthrough. Deny by default */
+}
+
+static int upload(char *dir)
+{
+ /* Timeout as string */
+ char timeout_buf[64];
+ const char *path;
+
+ loginfo("Request for '%s'", dir);
+
+ if (!(path = path_ok(dir)))
+ return -1;
+
+ /*
+ * Security on the cheap.
+ *
+ * We want a readable HEAD, usable "objects" directory, and
+ * a "git-daemon-export-ok" flag that says that the other side
+ * is ok with us doing this.
+ *
+ * path_ok() uses enter_repo() and does whitelist checking.
+ * We only need to make sure the repository is exported.
+ */
+
+ if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
+ logerror("'%s': repository not exported.", path);
+ errno = EACCES;
+ return -1;
+ }
+
+ /*
+ * We'll ignore SIGTERM from now on, we have a
+ * good client.
+ */
+ signal(SIGTERM, SIG_IGN);
+
+ snprintf(timeout_buf, sizeof timeout_buf, "--timeout=%u", timeout);
+
+ /* git-upload-pack only ever reads stuff, so this is safe */
+ execl_git_cmd("upload-pack", "--strict", timeout_buf, ".", NULL);
+ return -1;
+}
+
+static int execute(void)
+{
+ static char line[1000];
+ int pktlen, len;
+
+ alarm(init_timeout ? init_timeout : timeout);
+ pktlen = packet_read_line(0, line, sizeof(line));
+ alarm(0);
+
+ len = strlen(line);
+ if (pktlen != len)
+ loginfo("Extended attributes (%d bytes) exist <%.*s>",
+ (int) pktlen - len,
+ (int) pktlen - len, line + len + 1);
+ if (len && line[len-1] == '\n')
+ line[--len] = 0;
+
+ if (!strncmp("git-upload-pack ", line, 16))
+ return upload(line+16);
+
+ logerror("Protocol error: '%s'", line);
+ return -1;
+}
+
+
+/*
+ * 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) {
+ unsigned idx;
+
+ close(incoming);
+ if (pid < 0)
+ return;
+
+ 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;
+
+#ifndef NO_IPV6
+ } 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;
+#endif
+ }
+ loginfo("Connection from %s:%d", addrbuf, port);
+
+ exit(execute());
+}
+
+static void child_handler(int signo)
+{
+ for (;;) {
+ 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;
+ }
+}
+
+static int set_reuse_addr(int sockfd)
+{
+ int on = 1;
+
+ if (!reuseaddr)
+ return 0;
+ return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
+ &on, sizeof(on));
+}
+
+#ifndef NO_IPV6
+
+static int socksetup(int port, int **socklist_p)
+{
+ int socknum = 0, *socklist = NULL;
+ int maxfd = -1;
+ char pbuf[NI_MAXSERV];
+
+ struct addrinfo hints, *ai0, *ai;
+ int gai;
+
+ 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));
+
+ 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 (set_reuse_addr(sockfd)) {
+ close(sockfd);
+ continue;
+ }
+
+ 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;
+
+ if (maxfd < sockfd)
+ maxfd = sockfd;
+ }
+
+ freeaddrinfo(ai0);
+
+ *socklist_p = socklist;
+ return socknum;
+}
+
+#else /* NO_IPV6 */
+
+static int socksetup(int port, int **socklist_p)
+{
+ struct sockaddr_in sin;
+ int sockfd;
+
+ sockfd = socket(AF_INET, SOCK_STREAM, 0);
+ if (sockfd < 0)
+ return 0;
+
+ memset(&sin, 0, sizeof sin);
+ sin.sin_family = AF_INET;
+ sin.sin_addr.s_addr = htonl(INADDR_ANY);
+ sin.sin_port = htons(port);
+
+ if (set_reuse_addr(sockfd)) {
+ close(sockfd);
+ return 0;
+ }
+
+ if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
+ close(sockfd);
+ return 0;
+ }
+
+ if (listen(sockfd, 5) < 0) {
+ close(sockfd);
+ return 0;
+ }
+
+ *socklist_p = xmalloc(sizeof(int));
+ **socklist_p = sockfd;
+ return 1;
+}
+
+#endif
+
+static int service_loop(int socknum, int *socklist)
+{
+ struct pollfd *pfd;
+ int i;
+
+ pfd = xcalloc(socknum, sizeof(struct pollfd));
+
+ for (i = 0; i < socknum; i++) {
+ pfd[i].fd = socklist[i];
+ pfd[i].events = POLLIN;
+ }
+
+ signal(SIGCHLD, child_handler);
+
+ for (;;) {
+ int i;
+
+ if (poll(pfd, socknum, -1) < 0) {
+ if (errno != EINTR) {
+ error("poll failed, resuming: %s",
+ strerror(errno));
+ sleep(1);
+ }
+ continue;
+ }
+
+ for (i = 0; i < socknum; i++) {
+ if (pfd[i].revents & POLLIN) {
+ struct sockaddr_storage ss;
+ unsigned int sslen = sizeof(ss);
+ int incoming = accept(pfd[i].fd, (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);
+ }
+ }
+ }
+}
+
+static int serve(int port)
+{
+ int socknum, *socklist;
+
+ socknum = socksetup(port, &socklist);
+ if (socknum == 0)
+ die("unable to allocate any listen sockets on port %u", port);
+
+ return service_loop(socknum, socklist);
+}
+
+int main(int argc, char **argv)
+{
+ int port = DEFAULT_GIT_PORT;
+ int inetd_mode = 0;
+ int i;
+
+ for (i = 1; i < argc; i++) {
+ char *arg = argv[i];
+
+ if (!strncmp(arg, "--port=", 7)) {
+ char *end;
+ unsigned long n;
+ n = strtoul(arg+7, &end, 0);
+ if (arg[7] && !*end) {
+ port = n;
+ continue;
+ }
+ }
+ if (!strcmp(arg, "--inetd")) {
+ inetd_mode = 1;
+ log_syslog = 1;
+ continue;
+ }
+ if (!strcmp(arg, "--verbose")) {
+ verbose = 1;
+ continue;
+ }
+ if (!strcmp(arg, "--syslog")) {
+ log_syslog = 1;
+ continue;
+ }
+ if (!strcmp(arg, "--export-all")) {
+ export_all_trees = 1;
+ continue;
+ }
+ if (!strncmp(arg, "--timeout=", 10)) {
+ timeout = atoi(arg+10);
+ continue;
+ }
+ if (!strncmp(arg, "--init-timeout=", 15)) {
+ init_timeout = atoi(arg+15);
+ continue;
+ }
+ if (!strcmp(arg, "--strict-paths")) {
+ strict_paths = 1;
+ continue;
+ }
+ if (!strncmp(arg, "--base-path=", 12)) {
+ base_path = arg+12;
+ continue;
+ }
+ if (!strcmp(arg, "--reuseaddr")) {
+ reuseaddr = 1;
+ continue;
+ }
+ if (!strcmp(arg, "--user-path")) {
+ user_path = "";
+ continue;
+ }
+ if (!strncmp(arg, "--user-path=", 12)) {
+ user_path = arg + 12;
+ continue;
+ }
+ if (!strcmp(arg, "--")) {
+ ok_paths = &argv[i+1];
+ break;
+ } else if (arg[0] != '-') {
+ ok_paths = &argv[i];
+ break;
+ }
+
+ usage(daemon_usage);
+ }
+
+ if (log_syslog)
+ openlog("git-daemon", 0, LOG_DAEMON);
+
+ if (strict_paths && (!ok_paths || !*ok_paths)) {
+ if (!inetd_mode)
+ die("git-daemon: option --strict-paths requires a whitelist");
+
+ logerror("option --strict-paths requires a whitelist");
+ exit (1);
+ }
+
+ if (inetd_mode) {
+ fclose(stderr); //FIXME: workaround
+ return execute();
+ }
+
+ return serve(port);
+}
generated by cgit 1.2.3-korg (git 2.39.0) at 2024-05-17 20:26:27 +0000