clientserver.c

Rsync 3.0.5 source code

/*
 * The socket based protocol for setting up a connection with rsyncd.
 *
 * Copyright (C) 1998-2001 Andrew Tridgell <[e-mail]>
 * Copyright (C) 2001-2002 Martin Pool <[e-mail]>
 * Copyright (C) 2002-2008 Wayne Davison
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, visit the http://fsf.org website.
 */

#include "rsync.h"
#include "ifuncs.h"

extern int quiet;
extern int verbose;
extern int dry_run;
extern int output_motd;
extern int list_only;
extern int am_sender;
extern int am_server;
extern int am_daemon;
extern int am_root;
extern int rsync_port;
extern int protect_args;
extern int ignore_errors;
extern int preserve_xattrs;
extern int kluge_around_eof;
extern int daemon_over_rsh;
extern int sanitize_paths;
extern int numeric_ids;
extern int filesfrom_fd;
extern int remote_protocol;
extern int protocol_version;
extern int io_timeout;
extern int no_detach;
extern int write_batch;
extern int default_af_hint;
extern int logfile_format_has_i;
extern int logfile_format_has_o_or_i;
extern mode_t orig_umask;
extern char *bind_address;
extern char *sockopts;
extern char *config_file;
extern char *logfile_format;
extern char *files_from;
extern char *tmpdir;
extern struct chmod_mode_struct *chmod_modes;
extern struct filter_list_struct daemon_filter_list;
extern char curr_dir[];
#ifdef ICONV_OPTION
extern char *iconv_opt;
extern iconv_t ic_send, ic_recv;
#endif

char *auth_user;
int read_only = 0;
int module_id = -1;
int munge_symlinks = 0;
struct chmod_mode_struct *daemon_chmod_modes;

/* module_dirlen is the length of the module_dir string when in daemon
 * mode and module_dir is not "/"; otherwise 0.  (Note that a chroot-
 * enabled module can have a non-"/" module_dir these days.) */
char *module_dir = NULL;
unsigned int module_dirlen = 0;

char *full_module_path;

static int rl_nulls = 0;

#ifdef HAVE_SIGACTION
static struct sigaction sigact;
#endif

/**
 * Run a client connected to an rsyncd.  The alternative to this
 * function for remote-shell connections is do_cmd().
 *
 * After negotiating which module to use and reading the server's
 * motd, this hands over to client_run().  Telling the server the
 * module will cause it to chroot/setuid/etc.
 *
 * Instead of doing a transfer, the client may at this stage instead
 * get a listing of remote modules and exit.
 *
 * @return -1 for error in startup, or the result of client_run().
 * Either way, it eventually gets passed to exit_cleanup().
 **/
int start_socket_client(char *host, int remote_argc, char *remote_argv[],
			int argc, char *argv[])
{
	int fd, ret;
	char *p, *user = NULL;

	/* This is redundant with code in start_inband_exchange(), but this
	 * short-circuits a problem in the client before we open a socket,
	 * and the extra check won't hurt. */
	if (**remote_argv == '/') {
		rprintf(FERROR,
			"ERROR: The remote path must start with a module name not a /\n");
		return -1;
	}

	if ((p = strrchr(host, '@')) != NULL) {
		user = host;
		host = p+1;
		*p = '\0';
	}

	fd = open_socket_out_wrapped(host, rsync_port, bind_address,
				     default_af_hint);
	if (fd == -1)
		exit_cleanup(RERR_SOCKETIO);

#ifdef ICONV_CONST
	setup_iconv();
#endif

	ret = start_inband_exchange(fd, fd, user, remote_argc, remote_argv);

	return ret ? ret : client_run(fd, fd, -1, argc, argv);
}

static int exchange_protocols(int f_in, int f_out, char *buf, size_t bufsiz, int am_client)
{
	int remote_sub = -1;
#if SUBPROTOCOL_VERSION != 0
	int our_sub = protocol_version < PROTOCOL_VERSION ? 0 : SUBPROTOCOL_VERSION;
#else
	int our_sub = 0;
#endif
	char *motd;

	io_printf(f_out, "@RSYNCD: %d.%d\n", protocol_version, our_sub);

	if (!am_client) {
		motd = lp_motd_file();
		if (motd && *motd) {
			FILE *f = fopen(motd,"r");
			while (f && !feof(f)) {
				int len = fread(buf, 1, bufsiz - 1, f);
				if (len > 0)
					write_buf(f_out, buf, len);
			}
			if (f)
				fclose(f);
			write_sbuf(f_out, "\n");
		}
	}

	/* This strips the \n. */
	if (!read_line_old(f_in, buf, bufsiz)) {
		if (am_client)
			rprintf(FERROR, "rsync: did not see server greeting\n");
		return -1;
	}

	if (sscanf(buf, "@RSYNCD: %d.%d", &remote_protocol, &remote_sub) < 1) {
		if (am_client)
			rprintf(FERROR, "rsync: server sent \"%s\" rather than greeting\n", buf);
		else
			io_printf(f_out, "@ERROR: protocol startup error\n");
		return -1;
	}

	if (remote_sub < 0) {
		if (remote_protocol == 30) {
			if (am_client)
				rprintf(FERROR, "rsync: server is speaking an incompatible beta of protocol 30\n");
			else
				io_printf(f_out, "@ERROR: your client is speaking an incompatible beta of protocol 30\n");
			return -1;
		}
		remote_sub = 0;
	}

	if (protocol_version > remote_protocol) {
		protocol_version = remote_protocol;
		if (remote_sub)
			protocol_version--;
	} else if (protocol_version == remote_protocol) {
		if (remote_sub != our_sub)
			protocol_version--;
	}
#if SUBPROTOCOL_VERSION != 0
	else if (protocol_version < remote_protocol) {
		if (our_sub)
			protocol_version--;
	}
#endif

	if (protocol_version >= 30)
		rl_nulls = 1;

	return 0;
}

int start_inband_exchange(int f_in, int f_out, const char *user, int argc, char *argv[])
{
	int i, modlen;
	char line[BIGPATHBUFLEN];
	char *sargs[MAX_ARGS];
	int sargc = 0;
	char *p, *modname;

	assert(argc > 0 && *argv != NULL);

	if (**argv == '/') {
		rprintf(FERROR,
			"ERROR: The remote path must start with a module name\n");
		return -1;
	}

	if (!(p = strchr(*argv, '/')))
		modlen = strlen(*argv);
	else
		modlen = p - *argv;

	if (!(modname = new_array(char, modlen+1+1))) /* room for '/' & '\0' */
		out_of_memory("start_inband_exchange");
	strlcpy(modname, *argv, modlen + 1);
	modname[modlen] = '/';
	modname[modlen+1] = '\0';

	if (!user)
		user = getenv("USER");
	if (!user)
		user = getenv("LOGNAME");

	if (exchange_protocols(f_in, f_out, line, sizeof line, 1) < 0)
		return -1;

	/* set daemon_over_rsh to false since we need to build the
	 * true set of args passed through the rsh/ssh connection;
	 * this is a no-op for direct-socket-connection mode */
	daemon_over_rsh = 0;
	server_options(sargs, &sargc);

	if (sargc >= MAX_ARGS - 2)
		goto arg_overflow;

	sargs[sargc++] = ".";

	while (argc > 0) {
		if (sargc >= MAX_ARGS - 1) {
		  arg_overflow:
			rprintf(FERROR, "internal: args[] overflowed in do_cmd()\n");
			exit_cleanup(RERR_SYNTAX);
		}
		if (strncmp(*argv, modname, modlen) == 0
		 && argv[0][modlen] == '\0')
			sargs[sargc++] = modname; /* we send "modname/" */
		else
			sargs[sargc++] = *argv;
		argv++;
		argc--;
	}

	sargs[sargc] = NULL;

	if (verbose > 1)
		print_child_argv("sending daemon args:", sargs);

	io_printf(f_out, "%.*s\n", modlen, modname);

	/* Old servers may just drop the connection here,
	 rather than sending a proper EXIT command.  Yuck. */
	kluge_around_eof = list_only && protocol_version < 25 ? 1 : 0;

	while (1) {
		if (!read_line_old(f_in, line, sizeof line)) {
			rprintf(FERROR, "rsync: didn't get server startup line\n");
			return -1;
		}

		if (strncmp(line,"@RSYNCD: AUTHREQD ",18) == 0) {
			auth_client(f_out, user, line+18);
			continue;
		}

		if (strcmp(line,"@RSYNCD: OK") == 0)
			break;

		if (strcmp(line,"@RSYNCD: EXIT") == 0) {
			/* This is sent by recent versions of the
			 * server to terminate the listing of modules.
			 * We don't want to go on and transfer
			 * anything; just exit. */
			exit(0);
		}

		if (strncmp(line, "@ERROR", 6) == 0) {
			rprintf(FERROR, "%s\n", line);
			/* This is always fatal; the server will now
			 * close the socket. */
			return -1;
		}

		/* This might be a MOTD line or a module listing, but there is
		 * no way to differentiate it.  The manpage mentions this. */
		if (output_motd)
			rprintf(FINFO, "%s\n", line);
	}
	kluge_around_eof = 0;

	if (rl_nulls) {
		for (i = 0; i < sargc; i++) {
			if (!sargs[i]) /* stop at --protect-args NULL */
				break;
			write_sbuf(f_out, sargs[i]);
			write_byte(f_out, 0);
		}
		write_byte(f_out, 0);
	} else {
		for (i = 0; i < sargc; i++)
			io_printf(f_out, "%s\n", sargs[i]);
		write_sbuf(f_out, "\n");
	}

	if (protect_args)
		send_protected_args(f_out, sargs);

	if (protocol_version < 23) {
		if (protocol_version == 22 || !am_sender)
			io_start_multiplex_in();
	}

	free(modname);

	return 0;
}

static char *finish_pre_exec(pid_t pid, int fd, char *request,
			     char **early_argv, char **argv)
{
	int j = 0, status = -1;

	if (!request)
		request = "(NONE)";

	write_buf(fd, request, strlen(request)+1);
	if (early_argv) {
		for ( ; *early_argv; early_argv++)
			write_buf(fd, *early_argv, strlen(*early_argv)+1);
		j = 1; /* Skip arg0 name in argv. */
	}
	for ( ; argv[j]; j++) {
		write_buf(fd, argv[j], strlen(argv[j])+1);
		if (argv[j][0] == '.' && argv[j][1] == '\0')
			break;
	}
	write_byte(fd, 0);

	close(fd);

	if (wait_process(pid, &status, 0) < 0
	 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) {
		char *e;
		if (asprintf(&e, "pre-xfer exec returned failure (%d)%s%s\n",
			     status, status < 0 ? ": " : "",
			     status < 0 ? strerror(errno) : "") < 0)
			out_of_memory("finish_pre_exec");
		return e;
	}
	return NULL;
}

static int read_arg_from_pipe(int fd, char *buf, int limit)
{
	char *bp = buf, *eob = buf + limit - 1;

	while (1) {
	    int got = read(fd, bp, 1);
	    if (got != 1) {
		if (got < 0 && errno == EINTR)
			continue;
		return -1;
	    }
	    if (*bp == '\0')
		break;
	    if (bp < eob)
		bp++;
	}
	*bp = '\0';

	return bp - buf;
}

static int path_failure(int f_out, const char *dir, BOOL was_chdir)
{
	if (was_chdir)
		rsyserr(FLOG, errno, "chdir %s failed\n", dir);
	else
		rprintf(FLOG, "normalize_path(%s) failed\n", dir);
	io_printf(f_out, "@ERROR: chdir failed\n");
	return -1;
}

static int rsync_module(int f_in, int f_out, int i, char *addr, char *host)
{
	int argc;
	char **argv, **orig_argv, **orig_early_argv, *module_chdir;
	char line[BIGPATHBUFLEN];
	uid_t uid = (uid_t)-2;  /* canonically "nobody" */
	gid_t gid = (gid_t)-2;
	char *p, *err_msg = NULL;
	char *name = lp_name(i);
	int use_chroot = lp_use_chroot(i);
	int ret, pre_exec_fd = -1;
	pid_t pre_exec_pid = 0;
	char *request = NULL;

#ifdef ICONV_OPTION
	iconv_opt = lp_charset(i);
	if (*iconv_opt)
		setup_iconv();
	iconv_opt = NULL;
#endif

	if (!allow_access(addr, host, lp_hosts_allow(i), lp_hosts_deny(i))) {
		rprintf(FLOG, "rsync denied on module %s from %s (%s)\n",
			name, host, addr);
		if (!lp_list(i))
			io_printf(f_out, "@ERROR: Unknown module '%s'\n", name);
		else {
			io_printf(f_out,
				  "@ERROR: access denied to %s from %s (%s)\n",
				  name, host, addr);
		}
		return -1;
	}

	if (am_daemon && am_server) {
		rprintf(FLOG, "rsync allowed access on module %s from %s (%s)\n",
			name, host, addr);
	}

	if (!claim_connection(lp_lock_file(i), lp_max_connections(i))) {
		if (errno) {
			rsyserr(FLOG, errno, "failed to open lock file %s",
				lp_lock_file(i));
			io_printf(f_out, "@ERROR: failed to open lock file\n");
		} else {
			rprintf(FLOG, "max connections (%d) reached\n",
				lp_max_connections(i));
			io_printf(f_out, "@ERROR: max connections (%d) reached -- try again later\n",
				lp_max_connections(i));
		}
		return -1;
	}

	auth_user = auth_server(f_in, f_out, i, host, addr, "@RSYNCD: AUTHREQD ");

	if (!auth_user) {
		io_printf(f_out, "@ERROR: auth failed on module %s\n", name);
		return -1;
	}

	module_id = i;

	if (lp_read_only(i))
		read_only = 1;

	if (lp_transfer_logging(i) && !logfile_format)
		logfile_format = lp_log_format(i);
	if (log_format_has(logfile_format, 'i'))
		logfile_format_has_i = 1;
	if (logfile_format_has_i || log_format_has(logfile_format, 'o'))
		logfile_format_has_o_or_i = 1;

	am_root = (MY_UID() == 0);

	if (am_root) {
		p = lp_uid(i);
		if (!name_to_uid(p, &uid)) {
			if (!isDigit(p)) {
				rprintf(FLOG, "Invalid uid %s\n", p);
				io_printf(f_out, "@ERROR: invalid uid %s\n", p);
				return -1;
			}
			uid = atoi(p);
		}

		p = lp_gid(i);
		if (!name_to_gid(p, &gid)) {
			if (!isDigit(p)) {
				rprintf(FLOG, "Invalid gid %s\n", p);
				io_printf(f_out, "@ERROR: invalid gid %s\n", p);
				return -1;
			}
			gid = atoi(p);
		}
	}

	/* TODO: If we're not root, but the configuration requests
	 * that we change to some uid other than the current one, then
	 * log a warning. */

	/* TODO: Perhaps take a list of gids, and make them into the
	 * supplementary groups. */

	module_dir = lp_path(i);
	if (use_chroot) {
		if ((p = strstr(module_dir, "/./")) != NULL) {
			*p = '\0'; /* Temporary... */
			if (!(module_chdir = normalize_path(module_dir, True, NULL)))
				return path_failure(f_out, module_dir, False);
			*p = '/';
			if (!(p = normalize_path(p + 2, True, &module_dirlen)))
				return path_failure(f_out, strstr(module_dir, "/./"), False);
			if (!(full_module_path = normalize_path(module_dir, False, NULL)))
				full_module_path = module_dir;
			module_dir = p;
		} else {
			if (!(module_chdir = normalize_path(module_dir, False, NULL)))
				return path_failure(f_out, module_dir, False);
			full_module_path = module_chdir;
			module_dir = "/";
			module_dirlen = 1;
		}
	} else {
		if (!(module_chdir = normalize_path(module_dir, False, &module_dirlen)))
			return path_failure(f_out, module_dir, False);
		full_module_path = module_dir = module_chdir;