servconf.h

/* $OpenBSD: servconf.h,v 1.123 2016/11/30 03:00:05 djm Exp $ */

/*
 * Author: Tatu Ylonen <[email protected]>
 * Copyright (c) 1995 Tatu Ylonen <[email protected]>, Espoo, Finland
 *                    All rights reserved
 * Definitions for server configuration data and for the functions reading it.
 *
 * 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".
 */

#ifndef SERVCONF_H
#define SERVCONF_H

#define MAX_PORTS       256 /* Max # ports. */

#define MAX_ALLOW_USERS     256 /* Max # users on allow list. */
#define MAX_DENY_USERS      256 /* Max # users on deny list. */
#define MAX_ALLOW_GROUPS    256 /* Max # groups on allow list. */
#define MAX_DENY_GROUPS     256 /* Max # groups on deny list. */
#define MAX_SUBSYSTEMS      256 /* Max # subsystems. */
#define MAX_HOSTKEYS        256 /* Max # hostkeys. */
#define MAX_HOSTCERTS       256 /* Max # host certificates. */
#define MAX_ACCEPT_ENV      256 /* Max # of env vars. */
#define MAX_MATCH_GROUPS    256 /* Max # of groups for Match. */
#define MAX_AUTHKEYS_FILES  256 /* Max # of authorized_keys files. */
#define MAX_AUTH_METHODS    256 /* Max # of AuthenticationMethods. */

/* permit_root_login */
#define PERMIT_NOT_SET      -1
#define PERMIT_NO       0
#define PERMIT_FORCED_ONLY  1
#define PERMIT_NO_PASSWD    2
#define PERMIT_YES      3

/* use_privsep */
#define PRIVSEP_OFF     0
#define PRIVSEP_ON      1
#define PRIVSEP_NOSANDBOX   2

/* AllowTCPForwarding */
#define FORWARD_DENY        0
#define FORWARD_REMOTE      (1)
#define FORWARD_LOCAL       (1<<1)
#define FORWARD_ALLOW       (FORWARD_REMOTE|FORWARD_LOCAL)

#define DEFAULT_AUTH_FAIL_MAX   6   /* Default for MaxAuthTries */
#define DEFAULT_SESSIONS_MAX    10  /* Default for MaxSessions */

/* Magic name for internal sftp-server */
#define INTERNAL_SFTP_NAME  "internal-sftp"

typedef struct {
    u_int   num_ports;
    u_int   ports_from_cmdline;
    int ports[MAX_PORTS];   /* Port number to listen on. */
    u_int   num_queued_listens;
    char   **queued_listen_addrs;
    int    *queued_listen_ports;
    struct addrinfo *listen_addrs;  /* Addresses on which the server listens. */
    int     address_family;     /* Address family used by the server. */
    char   *host_key_files[MAX_HOSTKEYS];   /* Files containing host keys. */
    int     num_host_key_files;     /* Number of files for host keys. */
    char   *host_cert_files[MAX_HOSTCERTS]; /* Files containing host certs. */
    int     num_host_cert_files;     /* Number of files for host certs. */
    char   *host_key_agent;      /* ssh-agent socket for host keys. */
    char   *pid_file;   /* Where to put our pid */
    int     login_grace_time;   /* Disconnect if no auth in this time
                     * (sec). */
    int     permit_root_login;  /* PERMIT_*, see above */
    int     ignore_rhosts;  /* Ignore .rhosts and .shosts. */
    int     ignore_user_known_hosts;    /* Ignore ~/.ssh/known_hosts
                         * for RhostsRsaAuth */
    int     print_motd; /* If true, print /etc/motd. */
    int print_lastlog;  /* If true, print lastlog */
    int     x11_forwarding; /* If true, permit inet (spoofing) X11 fwd. */
    int     x11_display_offset; /* What DISPLAY number to start
                     * searching at */
    int     x11_use_localhost;  /* If true, use localhost for fake X11 server. */
    char   *xauth_location; /* Location of xauth program */
    int permit_tty; /* If false, deny pty allocation */
    int permit_user_rc; /* If false, deny ~/.ssh/rc execution */
    int     strict_modes;   /* If true, require string home dir modes. */
    int     tcp_keep_alive; /* If true, set SO_KEEPALIVE. */
    int ip_qos_interactive; /* IP ToS/DSCP/class for interactive */
    int ip_qos_bulk;        /* IP ToS/DSCP/class for bulk traffic */
    char   *ciphers;    /* Supported SSH2 ciphers. */
    char   *macs;       /* Supported SSH2 macs. */
    char   *kex_algorithms; /* SSH2 kex methods in order of preference. */
    struct ForwardOptions fwd_opts; /* forwarding options */
    SyslogFacility log_facility;    /* Facility for system logging. */
    LogLevel log_level; /* Level for system logging. */
    int     hostbased_authentication;   /* If true, permit ssh2 hostbased auth */
    int     hostbased_uses_name_from_packet_only; /* experimental */
    char   *hostbased_key_types;    /* Key types allowed for hostbased */
    char   *hostkeyalgorithms;  /* SSH2 server key types */
    int     pubkey_authentication;  /* If true, permit ssh2 pubkey authentication. */
    char   *pubkey_key_types;   /* Key types allowed for public key */
    int     kerberos_authentication;    /* If true, permit Kerberos
                         * authentication. */
    int     kerberos_or_local_passwd;   /* If true, permit kerberos
                         * and any other password
                         * authentication mechanism,
                         * such as SecurID or
                         * /etc/passwd */
    int     kerberos_ticket_cleanup;    /* If true, destroy ticket
                         * file on logout. */
#ifdef SESSION_HOOKS
        int     session_hooks_allow;        /* If true, permit user hooks */
        char*   session_hooks_startup_cmd;  /* cmd to be executed before */
        char*   session_hooks_shutdown_cmd; /* cmd to be executed after */
#endif
    int     kerberos_get_afs_token;     /* If true, try to get AFS token if
                         * authenticated with Kerberos. */
    int     gsi_allow_limited_proxy;    /* If true, accept limited proxies */
    int     gss_authentication; /* If true, permit GSSAPI authentication */
    int     gss_deleg_creds;    /* If true, store delegated GSSAPI credentials*/
    int     gss_keyex;      /* If true, permit GSSAPI key exchange */
    int     gss_cleanup_creds;  /* If true, destroy cred cache on logout */
    char*   gss_creds_path; /* If true, destroy cred cache on logout */
    int     gss_strict_acceptor;    /* If true, restrict the GSSAPI acceptor name */
    int     gss_store_rekey;
    int     password_authentication;    /* If true, permit password
                         * authentication. */
    int     kbd_interactive_authentication; /* If true, permit */
    int     challenge_response_authentication;
    int     permit_empty_passwd;    /* If false, do not permit empty
                     * passwords. */
    int     permit_user_env;    /* If true, read ~/.ssh/environment */
    int     compression;    /* If true, compression is allowed */
    int allow_tcp_forwarding; /* One of FORWARD_* */
    int allow_streamlocal_forwarding; /* One of FORWARD_* */
    int allow_agent_forwarding;
    int disable_forwarding;
    u_int num_allow_users;
    char   *allow_users[MAX_ALLOW_USERS];
    u_int num_deny_users;
    char   *deny_users[MAX_DENY_USERS];
    u_int num_allow_groups;
    char   *allow_groups[MAX_ALLOW_GROUPS];
    u_int num_deny_groups;
    char   *deny_groups[MAX_DENY_GROUPS];

    u_int num_subsystems;
    char   *subsystem_name[MAX_SUBSYSTEMS];
    char   *subsystem_command[MAX_SUBSYSTEMS];
    char   *subsystem_args[MAX_SUBSYSTEMS];

    u_int num_accept_env;
    char   *accept_env[MAX_ACCEPT_ENV];

    int max_startups_begin;
    int max_startups_rate;
    int max_startups;
    int max_authtries;
    int max_sessions;
    char   *banner;         /* SSH-2 banner message */
    int use_dns;
    int client_alive_interval;  /*
                     * poke the client this often to
                     * see if it's still there
                     */
    int client_alive_count_max; /*
                     * If the client is unresponsive
                     * for this many intervals above,
                     * disconnect the session
                     */

    u_int num_authkeys_files;   /* Files containing public keys */
    char   *authorized_keys_files[MAX_AUTHKEYS_FILES];

    char   *adm_forced_command;

    int use_pam;        /* Enable auth via PAM */
    int tcp_rcv_buf_poll;   /* poll tcp rcv window in autotuning kernels*/
    int permit_pam_user_change; /* Allow PAM to change user name */
    int hpn_disabled;       /* disable hpn functionality. false by default */
    int hpn_buffer_size;    /* set the hpn buffer size - default 3MB */

    int none_enabled;       /* Enable NONE cipher switch */

    int audit_disabled;     /* disable SSHD instrumentation */
    int     disable_multithreaded;  /*disable multithreaded aes-ctr cipher */
    
    int permit_tun;

    int num_permitted_opens;

    char   *chroot_directory;
    char   *revoked_keys_file;
    char   *trusted_user_ca_keys;
    char   *authorized_keys_command;
    char   *authorized_keys_command_user;
    char   *authorized_principals_file;
    char   *authorized_principals_command;
    char   *authorized_principals_command_user;

    int64_t rekey_limit;
    int rekey_interval;

    char   *version_addendum;   /* Appended to SSH banner */

    u_int   num_auth_methods;
    char   *auth_methods[MAX_AUTH_METHODS];

    int fingerprint_hash;
}       ServerOptions;

/* Information about the incoming connection as used by Match */
struct connection_info {
    const char *user;
    const char *host;   /* possibly resolved hostname */
    const char *address;    /* remote address */
    const char *laddress;   /* local address */
    int lport;      /* local port */
};


/*
 * These are string config options that must be copied between the
 * Match sub-config and the main config, and must be sent from the
 * privsep slave to the privsep master. We use a macro to ensure all
 * the options are copied and the copies are done in the correct order.
 *
 * NB. an option must appear in servconf.c:copy_set_server_options() or
 * COPY_MATCH_STRING_OPTS here but never both.
 */
#define COPY_MATCH_STRING_OPTS() do { \
        M_CP_STROPT(banner); \
        M_CP_STROPT(trusted_user_ca_keys); \
        M_CP_STROPT(revoked_keys_file); \
        M_CP_STROPT(authorized_keys_command); \
        M_CP_STROPT(authorized_keys_command_user); \
        M_CP_STROPT(authorized_principals_file); \
        M_CP_STROPT(authorized_principals_command); \
        M_CP_STROPT(authorized_principals_command_user); \
        M_CP_STROPT(hostbased_key_types); \
        M_CP_STROPT(pubkey_key_types); \
        M_CP_STRARRAYOPT(authorized_keys_files, num_authkeys_files); \
        M_CP_STRARRAYOPT(allow_users, num_allow_users); \
        M_CP_STRARRAYOPT(deny_users, num_deny_users); \
        M_CP_STRARRAYOPT(allow_groups, num_allow_groups); \
        M_CP_STRARRAYOPT(deny_groups, num_deny_groups); \
        M_CP_STRARRAYOPT(accept_env, num_accept_env); \
        M_CP_STRARRAYOPT(auth_methods, num_auth_methods); \
    } while (0)

struct connection_info *get_connection_info(int, int);
void     initialize_server_options(ServerOptions *);
void     fill_default_server_options(ServerOptions *);
int  process_server_config_line(ServerOptions *, char *, const char *, int,
         int *, struct connection_info *);
void     load_server_config(const char *, Buffer *);
void     parse_server_config(ServerOptions *, const char *, Buffer *,
         struct connection_info *);
void     parse_server_match_config(ServerOptions *, struct connection_info *);
int  parse_server_match_testspec(struct connection_info *, char *);
int  server_match_spec_complete(struct connection_info *);
void     copy_set_server_options(ServerOptions *, ServerOptions *, int);
void     dump_config(ServerOptions *);
char    *derelativise_path(const char *);

#endif              /* SERVCONF_H */