1 files changed, 176 insertions, 114 deletions

diff --git a/daemon.c b/daemon.c
index 4b02184576..be70cd4da0 100644
--- a/daemon.c
+++ b/daemon.c
@@ -43,9 +43,6 @@ static const char *base_path;
 static const char *interpolated_path;
 static int base_path_relaxed;
 
-/* Flag indicating client sent extra args. */
-static int saw_extended_args;
-
 /* 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.
@@ -56,10 +53,28 @@ static const char *user_path;
 static unsigned int timeout;
 static unsigned int init_timeout;
 
-static char *hostname;
-static char *canon_hostname;
-static char *ip_address;
-static char *tcp_port;
+struct hostinfo {
+	struct strbuf hostname;
+	struct strbuf canon_hostname;
+	struct strbuf ip_address;
+	struct strbuf tcp_port;
+	unsigned int hostname_lookup_done:1;
+	unsigned int saw_extended_args:1;
+};
+
+static void lookup_hostname(struct hostinfo *hi);
+
+static const char *get_canon_hostname(struct hostinfo *hi)
+{
+	lookup_hostname(hi);
+	return hi->canon_hostname.buf;
+}
+
+static const char *get_ip_address(struct hostinfo *hi)
+{
+	lookup_hostname(hi);
+	return hi->ip_address.buf;
+}
 
 static void logreport(int priority, const char *err, va_list params)
 {
@@ -106,7 +121,43 @@ static void NORETURN daemon_die(const char *err, va_list params)
 	exit(1);
 }
 
-static const char *path_ok(const char *directory)
+struct expand_path_context {
+	const char *directory;
+	struct hostinfo *hostinfo;
+};
+
+static size_t expand_path(struct strbuf *sb, const char *placeholder, void *ctx)
+{
+	struct expand_path_context *context = ctx;
+	struct hostinfo *hi = context->hostinfo;
+
+	switch (placeholder[0]) {
+	case 'H':
+		strbuf_addbuf(sb, &hi->hostname);
+		return 1;
+	case 'C':
+		if (placeholder[1] == 'H') {
+			strbuf_addstr(sb, get_canon_hostname(hi));
+			return 2;
+		}
+		break;
+	case 'I':
+		if (placeholder[1] == 'P') {
+			strbuf_addstr(sb, get_ip_address(hi));
+			return 2;
+		}
+		break;
+	case 'P':
+		strbuf_addbuf(sb, &hi->tcp_port);
+		return 1;
+	case 'D':
+		strbuf_addstr(sb, context->directory);
+		return 1;
+	}
+	return 0;
+}
+
+static const char *path_ok(const char *directory, struct hostinfo *hi)
 {
 	static char rpath[PATH_MAX];
 	static char interp_path[PATH_MAX];
@@ -142,16 +193,13 @@ static const char *path_ok(const char *directory)
 			dir = rpath;
 		}
 	}
-	else if (interpolated_path && saw_extended_args) {
+	else if (interpolated_path && hi->saw_extended_args) {
 		struct strbuf expanded_path = STRBUF_INIT;
-		struct strbuf_expand_dict_entry dict[6];
-
-		dict[0].placeholder = "H"; dict[0].value = hostname;
-		dict[1].placeholder = "CH"; dict[1].value = canon_hostname;
-		dict[2].placeholder = "IP"; dict[2].value = ip_address;
-		dict[3].placeholder = "P"; dict[3].value = tcp_port;
-		dict[4].placeholder = "D"; dict[4].value = directory;
-		dict[5].placeholder = NULL; dict[5].value = NULL;
+		struct expand_path_context context;
+
+		context.directory = directory;
+		context.hostinfo = hi;
+
 		if (*dir != '/') {
 			/* Allow only absolute */
 			logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
@@ -159,7 +207,7 @@ static const char *path_ok(const char *directory)
 		}
 
 		strbuf_expand(&expanded_path, interpolated_path,
-				strbuf_expand_dict_cb, &dict);
+			      expand_path, &context);
 		strlcpy(interp_path, expanded_path.buf, PATH_MAX);
 		strbuf_release(&expanded_path);
 		loginfo("Interpolated dir '%s'", interp_path);
@@ -230,23 +278,6 @@ struct daemon_service {
 	int overridable;
 };
 
-static struct daemon_service *service_looking_at;
-static int service_enabled;
-
-static int git_daemon_config(const char *var, const char *value, void *cb)
-{
-	const char *service;
-
-	if (skip_prefix(var, "daemon.", &service) &&
-	    !strcmp(service, service_looking_at->config_name)) {
-		service_enabled = git_config_bool(var, value);
-		return 0;
-	}
-
-	/* we are not interested in parsing any other configuration here */
-	return 0;
-}
-
 static int daemon_error(const char *dir, const char *msg)
 {
 	if (!informative_errors)
@@ -257,27 +288,25 @@ static int daemon_error(const char *dir, const char *msg)
 
 static const char *access_hook;
 
-static int run_access_hook(struct daemon_service *service, const char *dir, const char *path)
+static int run_access_hook(struct daemon_service *service, const char *dir,
+			   const char *path, struct hostinfo *hi)
 {
-	struct child_process child;
+	struct child_process child = CHILD_PROCESS_INIT;
 	struct strbuf buf = STRBUF_INIT;
 	const char *argv[8];
 	const char **arg = argv;
 	char *eol;
 	int seen_errors = 0;
 
-#define STRARG(x) ((x) ? (x) : "")
 	*arg++ = access_hook;
 	*arg++ = service->name;
 	*arg++ = path;
-	*arg++ = STRARG(hostname);
-	*arg++ = STRARG(canon_hostname);
-	*arg++ = STRARG(ip_address);
-	*arg++ = STRARG(tcp_port);
+	*arg++ = hi->hostname.buf;
+	*arg++ = get_canon_hostname(hi);
+	*arg++ = get_ip_address(hi);
+	*arg++ = hi->tcp_port.buf;
 	*arg = NULL;
-#undef STRARG
 
-	memset(&child, 0, sizeof(child));
 	child.use_shell = 1;
 	child.argv = argv;
 	child.no_stdin = 1;
@@ -320,10 +349,12 @@ error_return:
 	return -1;
 }
 
-static int run_service(const char *dir, struct daemon_service *service)
+static int run_service(const char *dir, struct daemon_service *service,
+		       struct hostinfo *hi)
 {
 	const char *path;
 	int enabled = service->enabled;
+	struct strbuf var = STRBUF_INIT;
 
 	loginfo("Request %s for '%s'", service->name, dir);
 
@@ -333,7 +364,7 @@ static int run_service(const char *dir, struct daemon_service *service)
 		return daemon_error(dir, "service not enabled");
 	}
 
-	if (!(path = path_ok(dir)))
+	if (!(path = path_ok(dir, hi)))
 		return daemon_error(dir, "no such repository");
 
 	/*
@@ -354,11 +385,9 @@ static int run_service(const char *dir, struct daemon_service *service)
 	}
 
 	if (service->overridable) {
-		service_looking_at = service;
-		service_enabled = -1;
-		git_config(git_daemon_config, NULL);
-		if (0 <= service_enabled)
-			enabled = service_enabled;
+		strbuf_addf(&var, "daemon.%s", service->config_name);
+		git_config_get_bool(var.buf, &enabled);
+		strbuf_release(&var);
 	}
 	if (!enabled) {
 		logerror("'%s': service not enabled for '%s'",
@@ -371,7 +400,7 @@ static int run_service(const char *dir, struct daemon_service *service)
 	 * Optionally, a hook can choose to deny access to the
 	 * repository depending on the phase of the moon.
 	 */
-	if (access_hook && run_access_hook(service, dir, path))
+	if (access_hook && run_access_hook(service, dir, path, hi))
 		return -1;
 
 	/*
@@ -406,9 +435,8 @@ static void copy_to_log(int fd)
 
 static int run_service_command(const char **argv)
 {
-	struct child_process cld;
+	struct child_process cld = CHILD_PROCESS_INIT;
 
-	memset(&cld, 0, sizeof(cld));
 	cld.argv = argv;
 	cld.git_cmd = 1;
 	cld.err = -1;
@@ -505,16 +533,46 @@ static void parse_host_and_port(char *hostport, char **host,
 }
 
 /*
+ * Sanitize a string from the client so that it's OK to be inserted into a
+ * filesystem path. Specifically, we disallow slashes, runs of "..", and
+ * trailing and leading dots, which means that the client cannot escape
+ * our base path via ".." traversal.
+ */
+static void sanitize_client(struct strbuf *out, const char *in)
+{
+	for (; *in; in++) {
+		if (*in == '/')
+			continue;
+		if (*in == '.' && (!out->len || out->buf[out->len - 1] == '.'))
+			continue;
+		strbuf_addch(out, *in);
+	}
+
+	while (out->len && out->buf[out->len - 1] == '.')
+		strbuf_setlen(out, out->len - 1);
+}
+
+/*
+ * Like sanitize_client, but we also perform any canonicalization
+ * to make life easier on the admin.
+ */
+static void canonicalize_client(struct strbuf *out, const char *in)
+{
+	sanitize_client(out, in);
+	strbuf_tolower(out);
+}
+
+/*
  * Read the host as supplied by the client connection.
  */
-static void parse_host_arg(char *extra_args, int buflen)
+static void parse_host_arg(struct hostinfo *hi, char *extra_args, int buflen)
 {
 	char *val;
 	int vallen;
 	char *end = extra_args + buflen;
 
 	if (extra_args < end && *extra_args) {
-		saw_extended_args = 1;
+		hi->saw_extended_args = 1;
 		if (strncasecmp("host=", extra_args, 5) == 0) {
 			val = extra_args + 5;
 			vallen = strlen(val) + 1;
@@ -523,12 +581,10 @@ static void parse_host_arg(char *extra_args, int buflen)
 				char *host;
 				char *port;
 				parse_host_and_port(val, &host, &port);
-				if (port) {
-					free(tcp_port);
-					tcp_port = xstrdup(port);
-				}
-				free(hostname);
-				hostname = xstrdup_tolower(host);
+				if (port)
+					sanitize_client(&hi->tcp_port, port);
+				canonicalize_client(&hi->hostname, host);
+				hi->hostname_lookup_done = 0;
 			}
 
 			/* On to the next one */
@@ -537,11 +593,14 @@ static void parse_host_arg(char *extra_args, int buflen)
 		if (extra_args < end && *extra_args)
 			die("Invalid request");
 	}
+}
 
-	/*
-	 * Locate canonical hostname and its IP address.
-	 */
-	if (hostname) {
+/*
+ * Locate canonical hostname and its IP address.
+ */
+static void lookup_hostname(struct hostinfo *hi)
+{
+	if (!hi->hostname_lookup_done && hi->hostname.len) {
 #ifndef NO_IPV6
 		struct addrinfo hints;
 		struct addrinfo *ai;
@@ -551,18 +610,20 @@ static void parse_host_arg(char *extra_args, int buflen)
 		memset(&hints, 0, sizeof(hints));
 		hints.ai_flags = AI_CANONNAME;
 
-		gai = getaddrinfo(hostname, NULL, &hints, &ai);
+		gai = getaddrinfo(hi->hostname.buf, NULL, &hints, &ai);
 		if (!gai) {
 			struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 
 			inet_ntop(AF_INET, &sin_addr->sin_addr,
 				  addrbuf, sizeof(addrbuf));
-			free(ip_address);
-			ip_address = xstrdup(addrbuf);
+			strbuf_addstr(&hi->ip_address, addrbuf);
 
-			free(canon_hostname);
-			canon_hostname = xstrdup(ai->ai_canonname ?
-						 ai->ai_canonname : ip_address);
+			if (ai->ai_canonname)
+				sanitize_client(&hi->canon_hostname,
+						ai->ai_canonname);
+			else
+				strbuf_addbuf(&hi->canon_hostname,
+					      &hi->ip_address);
 
 			freeaddrinfo(ai);
 		}
@@ -572,7 +633,7 @@ static void parse_host_arg(char *extra_args, int buflen)
 		char **ap;
 		static char addrbuf[HOST_NAME_MAX + 1];
 
-		hent = gethostbyname(hostname);
+		hent = gethostbyname(hi->hostname.buf);
 		if (hent) {
 			ap = hent->h_addr_list;
 			memset(&sa, 0, sizeof sa);
@@ -583,21 +644,39 @@ static void parse_host_arg(char *extra_args, int buflen)
 			inet_ntop(hent->h_addrtype, &sa.sin_addr,
 				  addrbuf, sizeof(addrbuf));
 
-			free(canon_hostname);
-			canon_hostname = xstrdup(hent->h_name);
-			free(ip_address);
-			ip_address = xstrdup(addrbuf);
+			sanitize_client(&hi->canon_hostname, hent->h_name);
+			strbuf_addstr(&hi->ip_address, addrbuf);
 		}
 #endif
+		hi->hostname_lookup_done = 1;
 	}
 }
 
+static void hostinfo_init(struct hostinfo *hi)
+{
+	memset(hi, 0, sizeof(*hi));
+	strbuf_init(&hi->hostname, 0);
+	strbuf_init(&hi->canon_hostname, 0);
+	strbuf_init(&hi->ip_address, 0);
+	strbuf_init(&hi->tcp_port, 0);
+}
+
+static void hostinfo_clear(struct hostinfo *hi)
+{
+	strbuf_release(&hi->hostname);
+	strbuf_release(&hi->canon_hostname);
+	strbuf_release(&hi->ip_address);
+	strbuf_release(&hi->tcp_port);
+}
 
 static int execute(void)
 {
 	char *line = packet_buffer;
 	int pktlen, len, i;
 	char *addr = getenv("REMOTE_ADDR"), *port = getenv("REMOTE_PORT");
+	struct hostinfo hi;
+
+	hostinfo_init(&hi);
 
 	if (addr)
 		loginfo("Connection from %s:%s", addr, port);
@@ -616,14 +695,8 @@ static int execute(void)
 		pktlen--;
 	}
 
-	free(hostname);
-	free(canon_hostname);
-	free(ip_address);
-	free(tcp_port);
-	hostname = canon_hostname = ip_address = tcp_port = NULL;
-
 	if (len != pktlen)
-		parse_host_arg(line + len + 1, pktlen - len - 1);
+		parse_host_arg(&hi, line + len + 1, pktlen - len - 1);
 
 	for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 		struct daemon_service *s = &(daemon_service[i]);
@@ -636,10 +709,13 @@ static int execute(void)
 			 * Note: The directory here is probably context sensitive,
 			 * and might depend on the actual service being performed.
 			 */
-			return run_service(arg, s);
+			int rc = run_service(arg, s, &hi);
+			hostinfo_clear(&hi);
+			return rc;
 		}
 	}
 
+	hostinfo_clear(&hi);
 	logerror("Protocol error: '%s'", line);
 	return -1;
 }
@@ -726,6 +802,7 @@ static void check_dead_children(void)
 			/* remove the child */
 			*cradle = blanket->next;
 			live_children--;
+			child_process_clear(&blanket->cld);
 			free(blanket);
 		} else
 			cradle = &blanket->next;
@@ -734,9 +811,7 @@ static void check_dead_children(void)
 static char **cld_argv;
 static void handle(int incoming, struct sockaddr *addr, socklen_t addrlen)
 {
-	struct child_process cld = { NULL };
-	char addrbuf[300] = "REMOTE_ADDR=", portbuf[300];
-	char *env[] = { addrbuf, portbuf, NULL };
+	struct child_process cld = CHILD_PROCESS_INIT;
 
 	if (max_connections && live_children >= max_connections) {
 		kill_some_child();
@@ -750,27 +825,23 @@ static void handle(int incoming, struct sockaddr *addr, socklen_t addrlen)
 	}
 
 	if (addr->sa_family == AF_INET) {
+		char buf[128] = "";
 		struct sockaddr_in *sin_addr = (void *) addr;
-		inet_ntop(addr->sa_family, &sin_addr->sin_addr, addrbuf + 12,
-		    sizeof(addrbuf) - 12);
-		snprintf(portbuf, sizeof(portbuf), "REMOTE_PORT=%d",
-		    ntohs(sin_addr->sin_port));
+		inet_ntop(addr->sa_family, &sin_addr->sin_addr, buf, sizeof(buf));
+		argv_array_pushf(&cld.env_array, "REMOTE_ADDR=%s", buf);
+		argv_array_pushf(&cld.env_array, "REMOTE_PORT=%d",
+				 ntohs(sin_addr->sin_port));
 #ifndef NO_IPV6
 	} else if (addr->sa_family == AF_INET6) {
+		char buf[128] = "";
 		struct sockaddr_in6 *sin6_addr = (void *) addr;
-
-		char *buf = addrbuf + 12;
-		*buf++ = '['; *buf = '\0'; /* stpcpy() is cool */
-		inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf,
-		    sizeof(addrbuf) - 13);
-		strcat(buf, "]");
-
-		snprintf(portbuf, sizeof(portbuf), "REMOTE_PORT=%d",
-		    ntohs(sin6_addr->sin6_port));
+		inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(buf));
+		argv_array_pushf(&cld.env_array, "REMOTE_ADDR=[%s]", buf);
+		argv_array_pushf(&cld.env_array, "REMOTE_PORT=%d",
+				 ntohs(sin6_addr->sin6_port));
 #endif
 	}
 
-	cld.env = (const char **)env;
 	cld.argv = (const char **)cld_argv;
 	cld.in = incoming;
 	cld.out = dup(incoming);
@@ -825,7 +896,7 @@ static const char *ip2str(int family, struct sockaddr *sin, socklen_t len)
 		inet_ntop(family, &((struct sockaddr_in*)sin)->sin_addr, ip, len);
 		break;
 	default:
-		strcpy(ip, "<unknown>");
+		xsnprintf(ip, sizeof(ip), "<unknown>");
 	}
 	return ip;
 }
@@ -840,7 +911,7 @@ static int setup_named_sock(char *listen_addr, int listen_port, struct socketlis
 	int gai;
 	long flags;
 
-	sprintf(pbuf, "%d", listen_port);
+	xsnprintf(pbuf, sizeof(pbuf), "%d", listen_port);
 	memset(&hints, 0, sizeof(hints));
 	hints.ai_family = AF_UNSPEC;
 	hints.ai_socktype = SOCK_STREAM;
@@ -1090,15 +1161,6 @@ static struct credentials *prepare_credentials(const char *user_name,
 }
 #endif
 
-static void store_pid(const char *path)
-{
-	FILE *f = fopen(path, "w");
-	if (!f)
-		die_errno("cannot open pid file '%s'", path);
-	if (fprintf(f, "%"PRIuMAX"\n", (uintmax_t) getpid()) < 0 || fclose(f) != 0)
-		die_errno("failed to write pid file '%s'", path);
-}
-
 static int serve(struct string_list *listen_addr, int listen_port,
     struct credentials *cred)
 {
@@ -1309,7 +1371,7 @@ int main(int argc, char **argv)
 		sanitize_stdfds();
 
 	if (pid_file)
-		store_pid(pid_file);
+		write_file(pid_file, "%"PRIuMAX, (uintmax_t) getpid());
 
 	/* prepare argv for serving-processes */
 	cld_argv = xmalloc(sizeof (char *) * (argc + 2));