- stevesk@cvs.openbsd.org 2006/08/01 23:36:12

[openssh-git.git] / servconf.c

/* $OpenBSD: servconf.c,v 1.163 2006/08/01 23:36:12 stevesk Exp $ */
/*
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 *
 * As far as I am concerned, the code I have written for this software
 * can be used freely for any purpose.  Any derived versions of this
 * software must be clearly marked as such, and if the derived work is
 * incompatible with the protocol description in the RFC file, it must be
 * called by a name other than "ssh" or "Secure Shell".
 */

#include "includes.h"

#include <sys/types.h>
#include <sys/socket.h>

#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "ssh.h"
#include "log.h"
#include "servconf.h"
#include "xmalloc.h"
#include "compat.h"
#include "pathnames.h"
#include "misc.h"
#include "cipher.h"
#include "kex.h"
#include "mac.h"
#include "match.h"
#include "channels.h"

static void add_listen_addr(ServerOptions *, char *, u_short);
static void add_one_listen_addr(ServerOptions *, char *, u_short);

/* Use of privilege separation or not */
extern int use_privsep;
extern Buffer cfg;

/* Initializes the server options to their default values. */

void
initialize_server_options(ServerOptions *options)
{
        memset(options, 0, sizeof(*options));

        /* Portable-specific options */
        options->use_pam = -1;

        /* Standard Options */
        options->num_ports = 0;
        options->ports_from_cmdline = 0;
        options->listen_addrs = NULL;
        options->address_family = -1;
        options->num_host_key_files = 0;
        options->pid_file = NULL;
        options->server_key_bits = -1;
        options->login_grace_time = -1;
        options->key_regeneration_time = -1;
        options->permit_root_login = PERMIT_NOT_SET;
        options->ignore_rhosts = -1;
        options->ignore_user_known_hosts = -1;
        options->print_motd = -1;
        options->print_lastlog = -1;
        options->x11_forwarding = -1;
        options->x11_display_offset = -1;
        options->x11_use_localhost = -1;
        options->xauth_location = NULL;
        options->strict_modes = -1;
        options->tcp_keep_alive = -1;
        options->log_facility = SYSLOG_FACILITY_NOT_SET;
        options->log_level = SYSLOG_LEVEL_NOT_SET;
        options->rhosts_rsa_authentication = -1;
        options->hostbased_authentication = -1;
        options->hostbased_uses_name_from_packet_only = -1;
        options->rsa_authentication = -1;
        options->pubkey_authentication = -1;
        options->kerberos_authentication = -1;
        options->kerberos_or_local_passwd = -1;
        options->kerberos_ticket_cleanup = -1;
        options->kerberos_get_afs_token = -1;
        options->gss_authentication=-1;
        options->gss_cleanup_creds = -1;
        options->password_authentication = -1;
        options->kbd_interactive_authentication = -1;
        options->challenge_response_authentication = -1;
        options->permit_empty_passwd = -1;
        options->permit_user_env = -1;
        options->use_login = -1;
        options->compression = -1;
        options->allow_tcp_forwarding = -1;
        options->num_allow_users = 0;
        options->num_deny_users = 0;
        options->num_allow_groups = 0;
        options->num_deny_groups = 0;
        options->ciphers = NULL;
        options->macs = NULL;
        options->protocol = SSH_PROTO_UNKNOWN;
        options->gateway_ports = -1;
        options->num_subsystems = 0;
        options->max_startups_begin = -1;
        options->max_startups_rate = -1;
        options->max_startups = -1;
        options->max_authtries = -1;
        options->banner = NULL;
        options->use_dns = -1;
        options->client_alive_interval = -1;
        options->client_alive_count_max = -1;
        options->authorized_keys_file = NULL;
        options->authorized_keys_file2 = NULL;
        options->num_accept_env = 0;
        options->permit_tun = -1;
        options->num_permitted_opens = -1;
        options->adm_forced_command = NULL;
}

void
fill_default_server_options(ServerOptions *options)
{
        /* Portable-specific options */
        if (options->use_pam == -1)
                options->use_pam = 0;

        /* Standard Options */
        if (options->protocol == SSH_PROTO_UNKNOWN)
                options->protocol = SSH_PROTO_1|SSH_PROTO_2;
        if (options->num_host_key_files == 0) {
                /* fill default hostkeys for protocols */
                if (options->protocol & SSH_PROTO_1)
                        options->host_key_files[options->num_host_key_files++] =
                            _PATH_HOST_KEY_FILE;
                if (options->protocol & SSH_PROTO_2) {
                        options->host_key_files[options->num_host_key_files++] =
                            _PATH_HOST_RSA_KEY_FILE;
                        options->host_key_files[options->num_host_key_files++] =
                            _PATH_HOST_DSA_KEY_FILE;
                }
        }
        if (options->num_ports == 0)
                options->ports[options->num_ports++] = SSH_DEFAULT_PORT;
        if (options->listen_addrs == NULL)
                add_listen_addr(options, NULL, 0);
        if (options->pid_file == NULL)
                options->pid_file = _PATH_SSH_DAEMON_PID_FILE;
        if (options->server_key_bits == -1)
                options->server_key_bits = 768;
        if (options->login_grace_time == -1)
                options->login_grace_time = 120;
        if (options->key_regeneration_time == -1)
                options->key_regeneration_time = 3600;
        if (options->permit_root_login == PERMIT_NOT_SET)
                options->permit_root_login = PERMIT_YES;
        if (options->ignore_rhosts == -1)
                options->ignore_rhosts = 1;
        if (options->ignore_user_known_hosts == -1)
                options->ignore_user_known_hosts = 0;
        if (options->print_motd == -1)
                options->print_motd = 1;
        if (options->print_lastlog == -1)
                options->print_lastlog = 1;
        if (options->x11_forwarding == -1)
                options->x11_forwarding = 0;
        if (options->x11_display_offset == -1)
                options->x11_display_offset = 10;
        if (options->x11_use_localhost == -1)
                options->x11_use_localhost = 1;
        if (options->xauth_location == NULL)
                options->xauth_location = _PATH_XAUTH;
        if (options->strict_modes == -1)
                options->strict_modes = 1;
        if (options->tcp_keep_alive == -1)
                options->tcp_keep_alive = 1;
        if (options->log_facility == SYSLOG_FACILITY_NOT_SET)
                options->log_facility = SYSLOG_FACILITY_AUTH;
        if (options->log_level == SYSLOG_LEVEL_NOT_SET)
                options->log_level = SYSLOG_LEVEL_INFO;
        if (options->rhosts_rsa_authentication == -1)
                options->rhosts_rsa_authentication = 0;
        if (options->hostbased_authentication == -1)
                options->hostbased_authentication = 0;
        if (options->hostbased_uses_name_from_packet_only == -1)
                options->hostbased_uses_name_from_packet_only = 0;
        if (options->rsa_authentication == -1)
                options->rsa_authentication = 1;
        if (options->pubkey_authentication == -1)
                options->pubkey_authentication = 1;
        if (options->kerberos_authentication == -1)
                options->kerberos_authentication = 0;
        if (options->kerberos_or_local_passwd == -1)
                options->kerberos_or_local_passwd = 1;
        if (options->kerberos_ticket_cleanup == -1)
                options->kerberos_ticket_cleanup = 1;
        if (options->kerberos_get_afs_token == -1)
                options->kerberos_get_afs_token = 0;
        if (options->gss_authentication == -1)
                options->gss_authentication = 0;
        if (options->gss_cleanup_creds == -1)
                options->gss_cleanup_creds = 1;
        if (options->password_authentication == -1)
                options->password_authentication = 1;
        if (options->kbd_interactive_authentication == -1)
                options->kbd_interactive_authentication = 0;
        if (options->challenge_response_authentication == -1)
                options->challenge_response_authentication = 1;
        if (options->permit_empty_passwd == -1)
                options->permit_empty_passwd = 0;
        if (options->permit_user_env == -1)
                options->permit_user_env = 0;
        if (options->use_login == -1)
                options->use_login = 0;
        if (options->compression == -1)
                options->compression = COMP_DELAYED;
        if (options->allow_tcp_forwarding == -1)
                options->allow_tcp_forwarding = 1;
        if (options->gateway_ports == -1)
                options->gateway_ports = 0;
        if (options->max_startups == -1)
                options->max_startups = 10;
        if (options->max_startups_rate == -1)
                options->max_startups_rate = 100;               /* 100% */
        if (options->max_startups_begin == -1)
                options->max_startups_begin = options->max_startups;
        if (options->max_authtries == -1)
                options->max_authtries = DEFAULT_AUTH_FAIL_MAX;
        if (options->use_dns == -1)
                options->use_dns = 1;
        if (options->client_alive_interval == -1)
                options->client_alive_interval = 0;
        if (options->client_alive_count_max == -1)
                options->client_alive_count_max = 3;
        if (options->authorized_keys_file2 == NULL) {
                /* authorized_keys_file2 falls back to authorized_keys_file */
                if (options->authorized_keys_file != NULL)
                        options->authorized_keys_file2 = options->authorized_keys_file;
                else
                        options->authorized_keys_file2 = _PATH_SSH_USER_PERMITTED_KEYS2;
        }
        if (options->authorized_keys_file == NULL)
                options->authorized_keys_file = _PATH_SSH_USER_PERMITTED_KEYS;
        if (options->permit_tun == -1)
                options->permit_tun = SSH_TUNMODE_NO;

        /* Turn privilege separation on by default */
        if (use_privsep == -1)
                use_privsep = 1;

#ifndef HAVE_MMAP
        if (use_privsep && options->compression == 1) {
                error("This platform does not support both privilege "
                    "separation and compression");
                error("Compression disabled");
                options->compression = 0;
        }
#endif

}

/* Keyword tokens. */
typedef enum {
        sBadOption,             /* == unknown option */
        /* Portable-specific options */
        sUsePAM,
        /* Standard Options */
        sPort, sHostKeyFile, sServerKeyBits, sLoginGraceTime, sKeyRegenerationTime,
        sPermitRootLogin, sLogFacility, sLogLevel,
        sRhostsRSAAuthentication, sRSAAuthentication,
        sKerberosAuthentication, sKerberosOrLocalPasswd, sKerberosTicketCleanup,
        sKerberosGetAFSToken,
        sKerberosTgtPassing, sChallengeResponseAuthentication,
        sPasswordAuthentication, sKbdInteractiveAuthentication,
        sListenAddress, sAddressFamily,
        sPrintMotd, sPrintLastLog, sIgnoreRhosts,
        sX11Forwarding, sX11DisplayOffset, sX11UseLocalhost,
        sStrictModes, sEmptyPasswd, sTCPKeepAlive,
        sPermitUserEnvironment, sUseLogin, sAllowTcpForwarding, sCompression,
        sAllowUsers, sDenyUsers, sAllowGroups, sDenyGroups,
        sIgnoreUserKnownHosts, sCiphers, sMacs, sProtocol, sPidFile,
        sGatewayPorts, sPubkeyAuthentication, sXAuthLocation, sSubsystem,
        sMaxStartups, sMaxAuthTries,
        sBanner, sUseDNS, sHostbasedAuthentication,
        sHostbasedUsesNameFromPacketOnly, sClientAliveInterval,
        sClientAliveCountMax, sAuthorizedKeysFile, sAuthorizedKeysFile2,
        sGssAuthentication, sGssCleanupCreds, sAcceptEnv, sPermitTunnel,
        sMatch, sPermitOpen, sForceCommand,
        sUsePrivilegeSeparation,
        sDeprecated, sUnsupported
} ServerOpCodes;

#define SSHCFG_GLOBAL   0x01    /* allowed in main section of sshd_config */
#define SSHCFG_MATCH    0x02    /* allowed inside a Match section */
#define SSHCFG_ALL      (SSHCFG_GLOBAL|SSHCFG_MATCH)

/* Textual representation of the tokens. */
static struct {
        const char *name;
        ServerOpCodes opcode;
        u_int flags;
} keywords[] = {
        /* Portable-specific options */
#ifdef USE_PAM
        { "usepam", sUsePAM, SSHCFG_GLOBAL },
#else
        { "usepam", sUnsupported, SSHCFG_GLOBAL },
#endif
        { "pamauthenticationviakbdint", sDeprecated, SSHCFG_GLOBAL },
        /* Standard Options */
        { "port", sPort, SSHCFG_GLOBAL },
        { "hostkey", sHostKeyFile, SSHCFG_GLOBAL },
        { "hostdsakey", sHostKeyFile, SSHCFG_GLOBAL },          /* alias */
        { "pidfile", sPidFile, SSHCFG_GLOBAL },
        { "serverkeybits", sServerKeyBits, SSHCFG_GLOBAL },
        { "logingracetime", sLoginGraceTime, SSHCFG_GLOBAL },
        { "keyregenerationinterval", sKeyRegenerationTime, SSHCFG_GLOBAL },
        { "permitrootlogin", sPermitRootLogin, SSHCFG_GLOBAL },
        { "syslogfacility", sLogFacility, SSHCFG_GLOBAL },
        { "loglevel", sLogLevel, SSHCFG_GLOBAL },
        { "rhostsauthentication", sDeprecated, SSHCFG_GLOBAL },
        { "rhostsrsaauthentication", sRhostsRSAAuthentication, SSHCFG_GLOBAL },
        { "hostbasedauthentication", sHostbasedAuthentication, SSHCFG_GLOBAL },
        { "hostbasedusesnamefrompacketonly", sHostbasedUsesNameFromPacketOnly, SSHCFG_GLOBAL },
        { "rsaauthentication", sRSAAuthentication, SSHCFG_GLOBAL },
        { "pubkeyauthentication", sPubkeyAuthentication, SSHCFG_GLOBAL },
        { "dsaauthentication", sPubkeyAuthentication, SSHCFG_GLOBAL },  /* alias */
#ifdef KRB5
        { "kerberosauthentication", sKerberosAuthentication, SSHCFG_GLOBAL },
        { "kerberosorlocalpasswd", sKerberosOrLocalPasswd, SSHCFG_GLOBAL },
        { "kerberosticketcleanup", sKerberosTicketCleanup, SSHCFG_GLOBAL },
#ifdef USE_AFS
        { "kerberosgetafstoken", sKerberosGetAFSToken, SSHCFG_GLOBAL },
#else
        { "kerberosgetafstoken", sUnsupported, SSHCFG_GLOBAL },
#endif
#else
        { "kerberosauthentication", sUnsupported, SSHCFG_GLOBAL },
        { "kerberosorlocalpasswd", sUnsupported, SSHCFG_GLOBAL },
        { "kerberosticketcleanup", sUnsupported, SSHCFG_GLOBAL },
        { "kerberosgetafstoken", sUnsupported, SSHCFG_GLOBAL },
#endif
        { "kerberostgtpassing", sUnsupported, SSHCFG_GLOBAL },
        { "afstokenpassing", sUnsupported, SSHCFG_GLOBAL },
#ifdef GSSAPI
        { "gssapiauthentication", sGssAuthentication, SSHCFG_GLOBAL },
        { "gssapicleanupcredentials", sGssCleanupCreds, SSHCFG_GLOBAL },
#else
        { "gssapiauthentication", sUnsupported, SSHCFG_GLOBAL },
        { "gssapicleanupcredentials", sUnsupported, SSHCFG_GLOBAL },
#endif
        { "passwordauthentication", sPasswordAuthentication, SSHCFG_GLOBAL },
        { "kbdinteractiveauthentication", sKbdInteractiveAuthentication, SSHCFG_GLOBAL },
        { "challengeresponseauthentication", sChallengeResponseAuthentication, SSHCFG_GLOBAL },
        { "skeyauthentication", sChallengeResponseAuthentication, SSHCFG_GLOBAL }, /* alias */
        { "checkmail", sDeprecated, SSHCFG_GLOBAL },
        { "listenaddress", sListenAddress, SSHCFG_GLOBAL },
        { "addressfamily", sAddressFamily, SSHCFG_GLOBAL },
        { "printmotd", sPrintMotd, SSHCFG_GLOBAL },
        { "printlastlog", sPrintLastLog, SSHCFG_GLOBAL },
        { "ignorerhosts", sIgnoreRhosts, SSHCFG_GLOBAL },
        { "ignoreuserknownhosts", sIgnoreUserKnownHosts, SSHCFG_GLOBAL },
        { "x11forwarding", sX11Forwarding, SSHCFG_ALL },
        { "x11displayoffset", sX11DisplayOffset, SSHCFG_ALL },
        { "x11uselocalhost", sX11UseLocalhost, SSHCFG_ALL },
        { "xauthlocation", sXAuthLocation, SSHCFG_GLOBAL },
        { "strictmodes", sStrictModes, SSHCFG_GLOBAL },
        { "permitemptypasswords", sEmptyPasswd, SSHCFG_GLOBAL },
        { "permituserenvironment", sPermitUserEnvironment, SSHCFG_GLOBAL },
        { "uselogin", sUseLogin, SSHCFG_GLOBAL },
        { "compression", sCompression, SSHCFG_GLOBAL },
        { "tcpkeepalive", sTCPKeepAlive, SSHCFG_GLOBAL },
        { "keepalive", sTCPKeepAlive, SSHCFG_GLOBAL },  /* obsolete alias */
        { "allowtcpforwarding", sAllowTcpForwarding, SSHCFG_ALL },
        { "allowusers", sAllowUsers, SSHCFG_GLOBAL },
        { "denyusers", sDenyUsers, SSHCFG_GLOBAL },
        { "allowgroups", sAllowGroups, SSHCFG_GLOBAL },
        { "denygroups", sDenyGroups, SSHCFG_GLOBAL },
        { "ciphers", sCiphers, SSHCFG_GLOBAL },
        { "macs", sMacs, SSHCFG_GLOBAL },
        { "protocol", sProtocol, SSHCFG_GLOBAL },
        { "gatewayports", sGatewayPorts, SSHCFG_ALL },
        { "subsystem", sSubsystem, SSHCFG_GLOBAL },
        { "maxstartups", sMaxStartups, SSHCFG_GLOBAL },
        { "maxauthtries", sMaxAuthTries, SSHCFG_GLOBAL },
        { "banner", sBanner, SSHCFG_GLOBAL },
        { "usedns", sUseDNS, SSHCFG_GLOBAL },
        { "verifyreversemapping", sDeprecated, SSHCFG_GLOBAL },
        { "reversemappingcheck", sDeprecated, SSHCFG_GLOBAL },
        { "clientaliveinterval", sClientAliveInterval, SSHCFG_GLOBAL },
        { "clientalivecountmax", sClientAliveCountMax, SSHCFG_GLOBAL },
        { "authorizedkeysfile", sAuthorizedKeysFile, SSHCFG_GLOBAL },
        { "authorizedkeysfile2", sAuthorizedKeysFile2, SSHCFG_GLOBAL },
        { "useprivilegeseparation", sUsePrivilegeSeparation, SSHCFG_GLOBAL },
        { "acceptenv", sAcceptEnv, SSHCFG_GLOBAL },
        { "permittunnel", sPermitTunnel, SSHCFG_GLOBAL },
        { "match", sMatch, SSHCFG_ALL },
        { "permitopen", sPermitOpen, SSHCFG_ALL },
        { "forcecommand", sForceCommand, SSHCFG_ALL },
        { NULL, sBadOption, 0 }
};

/*
 * Returns the number of the token pointed to by cp or sBadOption.
 */

static ServerOpCodes
parse_token(const char *cp, const char *filename,
            int linenum, u_int *flags)
{
        u_int i;

        for (i = 0; keywords[i].name; i++)
                if (strcasecmp(cp, keywords[i].name) == 0) {
                        *flags = keywords[i].flags;
                        return keywords[i].opcode;
                }

        error("%s: line %d: Bad configuration option: %s",
            filename, linenum, cp);
        return sBadOption;
}

static void
add_listen_addr(ServerOptions *options, char *addr, u_short port)
{
        u_int i;

        if (options->num_ports == 0)
                options->ports[options->num_ports++] = SSH_DEFAULT_PORT;
        if (options->address_family == -1)
                options->address_family = AF_UNSPEC;
        if (port == 0)
                for (i = 0; i < options->num_ports; i++)
                        add_one_listen_addr(options, addr, options->ports[i]);
        else
                add_one_listen_addr(options, addr, port);
}

static void
add_one_listen_addr(ServerOptions *options, char *addr, u_short port)
{
        struct addrinfo hints, *ai, *aitop;
        char strport[NI_MAXSERV];
        int gaierr;

        memset(&hints, 0, sizeof(hints));
        hints.ai_family = options->address_family;
        hints.ai_socktype = SOCK_STREAM;
        hints.ai_flags = (addr == NULL) ? AI_PASSIVE : 0;
        snprintf(strport, sizeof strport, "%u", port);
        if ((gaierr = getaddrinfo(addr, strport, &hints, &aitop)) != 0)
                fatal("bad addr or host: %s (%s)",
                    addr ? addr : "<NULL>",
                    gai_strerror(gaierr));
        for (ai = aitop; ai->ai_next; ai = ai->ai_next)
                ;
        ai->ai_next = options->listen_addrs;
        options->listen_addrs = aitop;
}

/*
 * The strategy for the Match blocks is that the config file is parsed twice.
 *
 * The first time is at startup.  activep is initialized to 1 and the
 * directives in the global context are processed and acted on.  Hitting a
 * Match directive unsets activep and the directives inside the block are
 * checked for syntax only.
 *
 * The second time is after a connection has been established but before
 * authentication.  activep is initialized to 2 and global config directives
 * are ignored since they have already been processed.  If the criteria in a
 * Match block is met, activep is set and the subsequent directives
 * processed and actioned until EOF or another Match block unsets it.  Any
 * options set are copied into the main server config.
 *
 * Potential additions/improvements:
 *  - Add Match support for pre-kex directives, eg Protocol, Ciphers.
 *
 *  - Add a Tag directive (idea from David Leonard) ala pf, eg:
 *      Match Address 192.168.0.*
 *              Tag trusted
 *      Match Group wheel
 *              Tag trusted
 *      Match Tag trusted
 *              AllowTcpForwarding yes
 *              GatewayPorts clientspecified
 *              [...]
 *
 *  - Add a PermittedChannelRequests directive
 *      Match Group shell
 *              PermittedChannelRequests session,forwarded-tcpip
 */

static int
match_cfg_line(char **condition, int line, const char *user, const char *host,
    const char *address)
{
        int result = 1;
        char *arg, *attrib, *cp = *condition;
        size_t len;

        if (user == NULL)
                debug3("checking syntax for 'Match %s'", cp);
        else
                debug3("checking match for '%s' user %s host %s addr %s", cp,
                    user ? user : "(null)", host ? host : "(null)",
                    address ? address : "(null)");

        while ((attrib = strdelim(&cp)) && *attrib != '\0') {
                if ((arg = strdelim(&cp)) == NULL || *arg == '\0') {
                        error("Missing Match criteria for %s", attrib);
                        return -1;
                }
                len = strlen(arg);
                if (strcasecmp(attrib, "user") == 0) {
                        if (!user) {
                                result = 0;
                                continue;
                        }
                        if (match_pattern_list(user, arg, len, 0) != 1)
                                result = 0;
                        else
                                debug("user %.100s matched 'User %.100s' at "
                                    "line %d", user, arg, line);
                } else if (strcasecmp(attrib, "host") == 0) {
                        if (!host) {
                                result = 0;
                                continue;
                        }
                        if (match_hostname(host, arg, len) != 1)
                                result = 0;
                        else
                                debug("connection from %.100s matched 'Host "
                                    "%.100s' at line %d", host, arg, line);
                } else if (strcasecmp(attrib, "address") == 0) {
                        debug("address '%s' arg '%s'", address, arg);
                        if (!address) {
                                result = 0;
                                continue;
                        }
                        if (match_hostname(address, arg, len) != 1)
                                result = 0;
                        else
                                debug("connection from %.100s matched 'Address "
                                    "%.100s' at line %d", address, arg, line);
                } else {
                        error("Unsupported Match attribute %s", attrib);
                        return -1;
                }
        }
        if (user != NULL)
                debug3("match %sfound", result ? "" : "not ");
        *condition = cp;
        return result;
}

#define WHITESPACE " \t\r\n"

int
process_server_config_line(ServerOptions *options, char *line,
    const char *filename, int linenum, int *activep, const char *user,
    const char *host, const char *address)
{
        char *cp, **charptr, *arg, *p;
        int cmdline = 0, *intptr, value, n;
        ServerOpCodes opcode;
        u_short port;
        u_int i, flags = 0;
        size_t len;

        cp = line;
        if ((arg = strdelim(&cp)) == NULL)
                return 0;
        /* Ignore leading whitespace */
        if (*arg == '\0')
                arg = strdelim(&cp);
        if (!arg || !*arg || *arg == '#')
                return 0;
        intptr = NULL;
        charptr = NULL;
        opcode = parse_token(arg, filename, linenum, &flags);

        if (activep == NULL) { /* We are processing a command line directive */
                cmdline = 1;
                activep = &cmdline;
        }
        if (*activep && opcode != sMatch)
                debug3("%s:%d setting %s %s", filename, linenum, arg, cp);
        if (*activep == 0 && !(flags & SSHCFG_MATCH)) {
                if (user == NULL) {
                        fatal("%s line %d: Directive '%s' is not allowed "
                            "within a Match block", filename, linenum, arg);
                } else { /* this is a directive we have already processed */
                        while (arg)
                                arg = strdelim(&cp);
                        return 0;
                }
        }

        switch (opcode) {
        /* Portable-specific options */
        case sUsePAM:
                intptr = &options->use_pam;
                goto parse_flag;

        /* Standard Options */
        case sBadOption:
                return -1;
        case sPort:
                /* ignore ports from configfile if cmdline specifies ports */
                if (options->ports_from_cmdline)
                        return 0;
                if (options->listen_addrs != NULL)
                        fatal("%s line %d: ports must be specified before "
                            "ListenAddress.", filename, linenum);
                if (options->num_ports >= MAX_PORTS)
                        fatal("%s line %d: too many ports.",
                            filename, linenum);
                arg = strdelim(&cp);
                if (!arg || *arg == '\0')
                        fatal("%s line %d: missing port number.",
                            filename, linenum);
                options->ports[options->num_ports++] = a2port(arg);
                if (options->ports[options->num_ports-1] == 0)
                        fatal("%s line %d: Badly formatted port number.",
                            filename, linenum);
                break;

        case sServerKeyBits:
                intptr = &options->server_key_bits;
parse_int:
                arg = strdelim(&cp);
                if (!arg || *arg == '\0')
                        fatal("%s line %d: missing integer value.",
                            filename, linenum);
                value = atoi(arg);
                if (*activep && *intptr == -1)
                        *intptr = value;
                break;

        case sLoginGraceTime:
                intptr = &options->login_grace_time;
parse_time:
                arg = strdelim(&cp);
                if (!arg || *arg == '\0')
                        fatal("%s line %d: missing time value.",
                            filename, linenum);
                if ((value = convtime(arg)) == -1)
                        fatal("%s line %d: invalid time value.",
                            filename, linenum);
                if (*intptr == -1)
                        *intptr = value;
                break;

        case sKeyRegenerationTime:
                intptr = &options->key_regeneration_time;
                goto parse_time;

        case sListenAddress:
                arg = strdelim(&cp);
                if (arg == NULL || *arg == '\0')
                        fatal("%s line %d: missing address",
                            filename, linenum);
                /* check for bare IPv6 address: no "[]" and 2 or more ":" */
                if (strchr(arg, '[') == NULL && (p = strchr(arg, ':')) != NULL
                    && strchr(p+1, ':') != NULL) {
                        add_listen_addr(options, arg, 0);
                        break;
                }
                p = hpdelim(&arg);
                if (p == NULL)
                        fatal("%s line %d: bad address:port usage",
                            filename, linenum);
                p = cleanhostname(p);
                if (arg == NULL)
                        port = 0;
                else if ((port = a2port(arg)) == 0)
                        fatal("%s line %d: bad port number", filename, linenum);

                add_listen_addr(options, p, port);

                break;

        case sAddressFamily:
                arg = strdelim(&cp);
                if (!arg || *arg == '\0')
                        fatal("%s line %d: missing address family.",
                            filename, linenum);
                intptr = &options->address_family;
                if (options->listen_addrs != NULL)
                        fatal("%s line %d: address family must be specified before "
                            "ListenAddress.", filename, linenum);
                if (strcasecmp(arg, "inet") == 0)
                        value = AF_INET;
                else if (strcasecmp(arg, "inet6") == 0)
                        value = AF_INET6;
                else if (strcasecmp(arg, "any") == 0)
                        value = AF_UNSPEC;
                else
                        fatal("%s line %d: unsupported address family \"%s\".",
                            filename, linenum, arg);
                if (*intptr == -1)
                        *intptr = value;
                break;

        case sHostKeyFile:
                intptr = &options->num_host_key_files;
                if (*intptr >= MAX_HOSTKEYS)
                        fatal("%s line %d: too many host keys specified (max %d).",
                            filename, linenum, MAX_HOSTKEYS);
                charptr = &options->host_key_files[*intptr];
parse_filename:
                arg = strdelim(&cp);
                if (!arg || *arg == '\0')
                        fatal("%s line %d: missing file name.",
                            filename, linenum);
                if (*activep && *charptr == NULL) {
                        *charptr = tilde_expand_filename(arg, getuid());
                        /* increase optional counter */
                        if (intptr != NULL)
                                *intptr = *intptr + 1;
                }
                break;

        case sPidFile:
                charptr = &options->pid_file;
                goto parse_filename;

        case sPermitRootLogin:
                intptr = &options->permit_root_login;
                arg = strdelim(&cp);
                if (!arg || *arg == '\0')
                        fatal("%s line %d: missing yes/"
                            "without-password/forced-commands-only/no "
                            "argument.", filename, linenum);
                value = 0;      /* silence compiler */
                if (strcmp(arg, "without-password") == 0)
                        value = PERMIT_NO_PASSWD;
                else if (strcmp(arg, "forced-commands-only") == 0)
                        value = PERMIT_FORCED_ONLY;
                else if (strcmp(arg, "yes") == 0)
                        value = PERMIT_YES;
                else if (strcmp(arg, "no") == 0)
                        value = PERMIT_NO;
                else
                        fatal("%s line %d: Bad yes/"
                            "without-password/forced-commands-only/no "
                            "argument: %s", filename, linenum, arg);
                if (*intptr == -1)
                        *intptr = value;
                break;

        case sIgnoreRhosts:
                intptr = &options->ignore_rhosts;
parse_flag:
                arg = strdelim(&cp);
                if (!arg || *arg == '\0')
                        fatal("%s line %d: missing yes/no argument.",
                            filename, linenum);
                value = 0;      /* silence compiler */
                if (strcmp(arg, "yes") == 0)
                        value = 1;
                else if (strcmp(arg, "no") == 0)
                        value = 0;
                else
                        fatal("%s line %d: Bad yes/no argument: %s",
                                filename, linenum, arg);
                if (*activep && *intptr == -1)
                        *intptr = value;
                break;

        case sIgnoreUserKnownHosts:
                intptr = &options->ignore_user_known_hosts;
                goto parse_flag;

        case sRhostsRSAAuthentication:
                intptr = &options->rhosts_rsa_authentication;
                goto parse_flag;

        case sHostbasedAuthentication:
                intptr = &options->hostbased_authentication;
                goto parse_flag;

        case sHostbasedUsesNameFromPacketOnly:
                intptr = &options->hostbased_uses_name_from_packet_only;
                goto parse_flag;

        case sRSAAuthentication:
                intptr = &options->rsa_authentication;
                goto parse_flag;

        case sPubkeyAuthentication:
                intptr = &options->pubkey_authentication;
                goto parse_flag;

        case sKerberosAuthentication:
                intptr = &options->kerberos_authentication;
                goto parse_flag;

        case sKerberosOrLocalPasswd:
                intptr = &options->kerberos_or_local_passwd;
                goto parse_flag;

        case sKerberosTicketCleanup:
                intptr = &options->kerberos_ticket_cleanup;
                goto parse_flag;

        case sKerberosGetAFSToken:
                intptr = &options->kerberos_get_afs_token;
                goto parse_flag;

        case sGssAuthentication:
                intptr = &options->gss_authentication;
                goto parse_flag;

        case sGssCleanupCreds:
                intptr = &options->gss_cleanup_creds;
                goto parse_flag;

        case sPasswordAuthentication:
                intptr = &options->password_authentication;
                goto parse_flag;

        case sKbdInteractiveAuthentication:
                intptr = &options->kbd_interactive_authentication;
                goto parse_flag;

        case sChallengeResponseAuthentication:
                intptr = &options->challenge_response_authentication;
                goto parse_flag;

        case sPrintMotd:
                intptr = &options->print_motd;
                goto parse_flag;

        case sPrintLastLog:
                intptr = &options->print_lastlog;
                goto parse_flag;

        case sX11Forwarding:
                intptr = &options->x11_forwarding;
                goto parse_flag;

        case sX11DisplayOffset:
                intptr = &options->x11_display_offset;
                goto parse_int;

        case sX11UseLocalhost:
                intptr = &options->x11_use_localhost;
                goto parse_flag;

        case sXAuthLocation:
                charptr = &options->xauth_location;
                goto parse_filename;

        case sStrictModes:
                intptr = &options->strict_modes;
                goto parse_flag;

        case sTCPKeepAlive:
                intptr = &options->tcp_keep_alive;
                goto parse_flag;

        case sEmptyPasswd:
                intptr = &options->permit_empty_passwd;
                goto parse_flag;

        case sPermitUserEnvironment:
                intptr = &options->permit_user_env;
                goto parse_flag;

        case sUseLogin:
                intptr = &options->use_login;
                goto parse_flag;

        case sCompression:
                intptr = &options->compression;
                arg = strdelim(&cp);
                if (!arg || *arg == '\0')
                        fatal("%s line %d: missing yes/no/delayed "
                            "argument.", filename, linenum);
                value = 0;      /* silence compiler */
                if (strcmp(arg, "delayed") == 0)
                        value = COMP_DELAYED;
                else if (strcmp(arg, "yes") == 0)
                        value = COMP_ZLIB;
                else if (strcmp(arg, "no") == 0)
                        value = COMP_NONE;
                else
                        fatal("%s line %d: Bad yes/no/delayed "
                            "argument: %s", filename, linenum, arg);
                if (*intptr == -1)
                        *intptr = value;
                break;

        case sGatewayPorts:
                intptr = &options->gateway_ports;
                arg = strdelim(&cp);
                if (!arg || *arg == '\0')
                        fatal("%s line %d: missing yes/no/clientspecified "
                            "argument.", filename, linenum);
                value = 0;      /* silence compiler */
                if (strcmp(arg, "clientspecified") == 0)
                        value = 2;
                else if (strcmp(arg, "yes") == 0)
                        value = 1;
                else if (strcmp(arg, "no") == 0)
                        value = 0;
                else
                        fatal("%s line %d: Bad yes/no/clientspecified "
                            "argument: %s", filename, linenum, arg);
                if (*intptr == -1)
                        *intptr = value;
                break;

        case sUseDNS:
                intptr = &options->use_dns;
                goto parse_flag;

        case sLogFacility:
                intptr = (int *) &options->log_facility;
                arg = strdelim(&cp);
                value = log_facility_number(arg);
                if (value == SYSLOG_FACILITY_NOT_SET)
                        fatal("%.200s line %d: unsupported log facility '%s'",
                            filename, linenum, arg ? arg : "<NONE>");
                if (*intptr == -1)
                        *intptr = (SyslogFacility) value;
                break;

        case sLogLevel:
                intptr = (int *) &options->log_level;
                arg = strdelim(&cp);
                value = log_level_number(arg);
                if (value == SYSLOG_LEVEL_NOT_SET)
                        fatal("%.200s line %d: unsupported log level '%s'",
                            filename, linenum, arg ? arg : "<NONE>");
                if (*intptr == -1)
                        *intptr = (LogLevel) value;
                break;

        case sAllowTcpForwarding:
                intptr = &options->allow_tcp_forwarding;
                goto parse_flag;

        case sUsePrivilegeSeparation:
                intptr = &use_privsep;
                goto parse_flag;

        case sAllowUsers:
                while ((arg = strdelim(&cp)) && *arg != '\0') {
                        if (options->num_allow_users >= MAX_ALLOW_USERS)
                                fatal("%s line %d: too many allow users.",
                                    filename, linenum);
                        options->allow_users[options->num_allow_users++] =
                            xstrdup(arg);
                }
                break;

        case sDenyUsers:
                while ((arg = strdelim(&cp)) && *arg != '\0') {
                        if (options->num_deny_users >= MAX_DENY_USERS)
                                fatal("%s line %d: too many deny users.",
                                    filename, linenum);
                        options->deny_users[options->num_deny_users++] =
                            xstrdup(arg);
                }
                break;

        case sAllowGroups:
                while ((arg = strdelim(&cp)) && *arg != '\0') {
                        if (options->num_allow_groups >= MAX_ALLOW_GROUPS)
                                fatal("%s line %d: too many allow groups.",
                                    filename, linenum);
                        options->allow_groups[options->num_allow_groups++] =
                            xstrdup(arg);
                }
                break;

        case sDenyGroups:
                while ((arg = strdelim(&cp)) && *arg != '\0') {
                        if (options->num_deny_groups >= MAX_DENY_GROUPS)
                                fatal("%s line %d: too many deny groups.",
                                    filename, linenum);
                        options->deny_groups[options->num_deny_groups++] = xstrdup(arg);
                }
                break;

        case sCiphers:
                arg = strdelim(&cp);
                if (!arg || *arg == '\0')
                        fatal("%s line %d: Missing argument.", filename, linenum);
                if (!ciphers_valid(arg))
                        fatal("%s line %d: Bad SSH2 cipher spec '%s'.",
                            filename, linenum, arg ? arg : "<NONE>");
                if (options->ciphers == NULL)
                        options->ciphers = xstrdup(arg);
                break;

        case sMacs:
                arg = strdelim(&cp);
                if (!arg || *arg == '\0')
                        fatal("%s line %d: Missing argument.", filename, linenum);
                if (!mac_valid(arg))
                        fatal("%s line %d: Bad SSH2 mac spec '%s'.",
                            filename, linenum, arg ? arg : "<NONE>");
                if (options->macs == NULL)
                        options->macs = xstrdup(arg);
                break;

        case sProtocol:
                intptr = &options->protocol;
                arg = strdelim(&cp);
                if (!arg || *arg == '\0')
                        fatal("%s line %d: Missing argument.", filename, linenum);
                value = proto_spec(arg);
                if (value == SSH_PROTO_UNKNOWN)
                        fatal("%s line %d: Bad protocol spec '%s'.",
                            filename, linenum, arg ? arg : "<NONE>");
                if (*intptr == SSH_PROTO_UNKNOWN)
                        *intptr = value;
                break;

        case sSubsystem:
                if (options->num_subsystems >= MAX_SUBSYSTEMS) {
                        fatal("%s line %d: too many subsystems defined.",
                            filename, linenum);
                }
                arg = strdelim(&cp);
                if (!arg || *arg == '\0')
                        fatal("%s line %d: Missing subsystem name.",
                            filename, linenum);
                if (!*activep) {
                        arg = strdelim(&cp);
                        break;
                }
                for (i = 0; i < options->num_subsystems; i++)
                        if (strcmp(arg, options->subsystem_name[i]) == 0)
                                fatal("%s line %d: Subsystem '%s' already defined.",
                                    filename, linenum, arg);
                options->subsystem_name[options->num_subsystems] = xstrdup(arg);
                arg = strdelim(&cp);
                if (!arg || *arg == '\0')
                        fatal("%s line %d: Missing subsystem command.",
                            filename, linenum);
                options->subsystem_command[options->num_subsystems] = xstrdup(arg);

                /* Collect arguments (separate to executable) */
                p = xstrdup(arg);
                len = strlen(p) + 1;
                while ((arg = strdelim(&cp)) != NULL && *arg != '\0') {
                        len += 1 + strlen(arg);
                        p = xrealloc(p, 1, len);
                        strlcat(p, " ", len);
                        strlcat(p, arg, len);
                }
                options->subsystem_args[options->num_subsystems] = p;
                options->num_subsystems++;
                break;

        case sMaxStartups:
                arg = strdelim(&cp);
                if (!arg || *arg == '\0')
                        fatal("%s line %d: Missing MaxStartups spec.",
                            filename, linenum);
                if ((n = sscanf(arg, "%d:%d:%d",
                    &options->max_startups_begin,
                    &options->max_startups_rate,
                    &options->max_startups)) == 3) {
                        if (options->max_startups_begin >
                            options->max_startups ||
                            options->max_startups_rate > 100 ||
                            options->max_startups_rate < 1)
                                fatal("%s line %d: Illegal MaxStartups spec.",
                                    filename, linenum);
                } else if (n != 1)
                        fatal("%s line %d: Illegal MaxStartups spec.",
                            filename, linenum);
                else
                        options->max_startups = options->max_startups_begin;
                break;

        case sMaxAuthTries:
                intptr = &options->max_authtries;
                goto parse_int;

        case sBanner:
                charptr = &options->banner;
                goto parse_filename;
        /*
         * These options can contain %X options expanded at
         * connect time, so that you can specify paths like:
         *
         * AuthorizedKeysFile   /etc/ssh_keys/%u
         */
        case sAuthorizedKeysFile:
        case sAuthorizedKeysFile2:
                charptr = (opcode == sAuthorizedKeysFile) ?
                    &options->authorized_keys_file :
                    &options->authorized_keys_file2;
                goto parse_filename;

        case sClientAliveInterval:
                intptr = &options->client_alive_interval;
                goto parse_time;

        case sClientAliveCountMax:
                intptr = &options->client_alive_count_max;
                goto parse_int;

        case sAcceptEnv:
                while ((arg = strdelim(&cp)) && *arg != '\0') {
                        if (strchr(arg, '=') != NULL)
                                fatal("%s line %d: Invalid environment name.",
                                    filename, linenum);
                        if (options->num_accept_env >= MAX_ACCEPT_ENV)
                                fatal("%s line %d: too many allow env.",
                                    filename, linenum);
                        if (!*activep)
                                break;
                        options->accept_env[options->num_accept_env++] =
                            xstrdup(arg);
                }
                break;

        case sPermitTunnel:
                intptr = &options->permit_tun;
                arg = strdelim(&cp);
                if (!arg || *arg == '\0')
                        fatal("%s line %d: Missing yes/point-to-point/"
                            "ethernet/no argument.", filename, linenum);
                value = 0;      /* silence compiler */
                if (strcasecmp(arg, "ethernet") == 0)
                        value = SSH_TUNMODE_ETHERNET;
                else if (strcasecmp(arg, "point-to-point") == 0)
                        value = SSH_TUNMODE_POINTOPOINT;
                else if (strcasecmp(arg, "yes") == 0)
                        value = SSH_TUNMODE_YES;
                else if (strcasecmp(arg, "no") == 0)
                        value = SSH_TUNMODE_NO;
                else
                        fatal("%s line %d: Bad yes/point-to-point/ethernet/"
                            "no argument: %s", filename, linenum, arg);
                if (*intptr == -1)
                        *intptr = value;
                break;

        case sMatch:
                if (cmdline)
                        fatal("Match directive not supported as a command-line "
                           "option");
                value = match_cfg_line(&cp, linenum, user, host, address);
                if (value < 0)
                        fatal("%s line %d: Bad Match condition", filename,
                            linenum);
                *activep = value;
                break;

        case sPermitOpen:
                arg = strdelim(&cp);
                if (!arg || *arg == '\0')
                        fatal("%s line %d: missing PermitOpen specification",
                            filename, linenum);
                if (strcmp(arg, "any") == 0) {
                        if (*activep) {
                                channel_clear_adm_permitted_opens();
                                options->num_permitted_opens = 0;
                        }
                        break;
                }
                for (; arg != NULL && *arg != '\0'; arg = strdelim(&cp)) {
                        p = hpdelim(&arg);
                        if (p == NULL)
                                fatal("%s line %d: missing host in PermitOpen",
                                    filename, linenum);
                        p = cleanhostname(p);
                        if (arg == NULL || (port = a2port(arg)) == 0)
                                fatal("%s line %d: bad port number in "
                                    "PermitOpen", filename, linenum);
                        if (*activep && options->num_permitted_opens == -1) {
                                channel_clear_adm_permitted_opens();
                                options->num_permitted_opens =
                                    channel_add_adm_permitted_opens(p, port);
                        }
                }
                break;

        case sForceCommand:
                if (cp == NULL)
                        fatal("%.200s line %d: Missing argument.", filename,
                            linenum);
                len = strspn(cp, WHITESPACE);
                if (*activep && options->adm_forced_command == NULL)
                        options->adm_forced_command = xstrdup(cp + len);
                return 0;

        case sDeprecated:
                logit("%s line %d: Deprecated option %s",
                    filename, linenum, arg);
                while (arg)
                    arg = strdelim(&cp);
                break;

        case sUnsupported:
                logit("%s line %d: Unsupported option %s",
                    filename, linenum, arg);
                while (arg)
                    arg = strdelim(&cp);
                break;

        default:
                fatal("%s line %d: Missing handler for opcode %s (%d)",
                    filename, linenum, arg, opcode);
        }
        if ((arg = strdelim(&cp)) != NULL && *arg != '\0')
                fatal("%s line %d: garbage at end of line; \"%.200s\".",
                    filename, linenum, arg);
        return 0;
}

/* Reads the server configuration file. */

void
load_server_config(const char *filename, Buffer *conf)
{
        char line[1024], *cp;
        FILE *f;

        debug2("%s: filename %s", __func__, filename);
        if ((f = fopen(filename, "r")) == NULL) {
                perror(filename);
                exit(1);
        }
        buffer_clear(conf);
        while (fgets(line, sizeof(line), f)) {
                /*
                 * Trim out comments and strip whitespace
                 * NB - preserve newlines, they are needed to reproduce
                 * line numbers later for error messages
                 */
                if ((cp = strchr(line, '#')) != NULL)
                        memcpy(cp, "\n", 2);
                cp = line + strspn(line, " \t\r");

                buffer_append(conf, cp, strlen(cp));
        }
        buffer_append(conf, "\0", 1);
        fclose(f);
        debug2("%s: done config len = %d", __func__, buffer_len(conf));
}

void
parse_server_match_config(ServerOptions *options, const char *user,
    const char *host, const char *address)
{
        ServerOptions mo;

        initialize_server_options(&mo);
        parse_server_config(&mo, "reprocess config", &cfg, user, host, address);
        copy_set_server_options(options, &mo);
}

/* Copy any (supported) values that are set */
void
copy_set_server_options(ServerOptions *dst, ServerOptions *src)
{
        if (src->allow_tcp_forwarding != -1)
                dst->allow_tcp_forwarding = src->allow_tcp_forwarding;
        if (src->gateway_ports != -1)
                dst->gateway_ports = src->gateway_ports;
        if (src->adm_forced_command != NULL) {
                if (dst->adm_forced_command != NULL)
                        xfree(dst->adm_forced_command);
                dst->adm_forced_command = src->adm_forced_command;
        }
        if (src->x11_display_offset != -1)
                dst->x11_display_offset = src->x11_display_offset;
        if (src->x11_forwarding != -1)
                dst->x11_forwarding = src->x11_forwarding;
        if (src->x11_use_localhost != -1)
                dst->x11_use_localhost = src->x11_use_localhost;
}

void
parse_server_config(ServerOptions *options, const char *filename, Buffer *conf,
    const char *user, const char *host, const char *address)
{
        int active, linenum, bad_options = 0;
        char *cp, *obuf, *cbuf;

        debug2("%s: config %s len %d", __func__, filename, buffer_len(conf));

        obuf = cbuf = xstrdup(buffer_ptr(conf));
        active = user ? 0 : 1;
        linenum = 1;
        while ((cp = strsep(&cbuf, "\n")) != NULL) {
                if (process_server_config_line(options, cp, filename,
                    linenum++, &active, user, host, address) != 0)
                        bad_options++;
        }
        xfree(obuf);
        if (bad_options > 0)
                fatal("%s: terminating, %d bad configuration options",
                    filename, bad_options);
}