/* * * ssh.h * * Author: Tatu Ylonen * * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland * All rights reserved * * Created: Fri Mar 17 17:09:37 1995 ylo * * Generic header file for ssh. * */ /* RCSID("$Id: ssh.h,v 1.30 1999/12/06 20:15:29 deraadt Exp $"); */ #ifndef SSH_H #define SSH_H #include "rsa.h" #include "cipher.h" /* * The default cipher used if IDEA is not supported by the remote host. It is * recommended that this be one of the mandatory ciphers (DES, 3DES), though * that is not required. */ #define SSH_FALLBACK_CIPHER SSH_CIPHER_3DES /* Cipher used for encrypting authentication files. */ #define SSH_AUTHFILE_CIPHER SSH_CIPHER_3DES /* Default port number. */ #define SSH_DEFAULT_PORT 22 /* Maximum number of TCP/IP ports forwarded per direction. */ #define SSH_MAX_FORWARDS_PER_DIRECTION 100 /* * Maximum number of RSA authentication identity files that can be specified * in configuration files or on the command line. */ #define SSH_MAX_IDENTITY_FILES 100 /* * Major protocol version. Different version indicates major incompatiblity * that prevents communication. */ #define PROTOCOL_MAJOR 1 /* * Minor protocol version. Different version indicates minor incompatibility * that does not prevent interoperation. */ #define PROTOCOL_MINOR 5 /* * Name for the service. The port named by this service overrides the * default port if present. */ #define SSH_SERVICE_NAME "ssh" #define ETCDIR "/etc" #define PIDDIR "/var/run" /* * System-wide file containing host keys of known hosts. This file should be * world-readable. */ #define SSH_SYSTEM_HOSTFILE ETCDIR "/ssh_known_hosts" /* * Of these, ssh_host_key must be readable only by root, whereas ssh_config * should be world-readable. */ #define HOST_KEY_FILE ETCDIR "/ssh_host_key" #define SERVER_CONFIG_FILE ETCDIR "/sshd_config" #define HOST_CONFIG_FILE ETCDIR "/ssh_config" #define SSH_PROGRAM "/usr/bin/ssh" /* * The process id of the daemon listening for connections is saved here to * make it easier to kill the correct daemon when necessary. */ #define SSH_DAEMON_PID_FILE PIDDIR "/sshd.pid" /* * The directory in user\'s home directory in which the files reside. The * directory should be world-readable (though not all files are). */ #define SSH_USER_DIR ".ssh" /* * Per-user file containing host keys of known hosts. This file need not be * readable by anyone except the user him/herself, though this does not * contain anything particularly secret. */ #define SSH_USER_HOSTFILE "~/.ssh/known_hosts" /* * Name of the default file containing client-side authentication key. This * file should only be readable by the user him/herself. */ #define SSH_CLIENT_IDENTITY ".ssh/identity" /* * Configuration file in user\'s home directory. This file need not be * readable by anyone but the user him/herself, but does not contain anything * particularly secret. If the user\'s home directory resides on an NFS * volume where root is mapped to nobody, this may need to be world-readable. */ #define SSH_USER_CONFFILE ".ssh/config" /* * File containing a list of those rsa keys that permit logging in as this * user. This file need not be readable by anyone but the user him/herself, * but does not contain anything particularly secret. If the user\'s home * directory resides on an NFS volume where root is mapped to nobody, this * may need to be world-readable. (This file is read by the daemon which is * running as root.) */ #define SSH_USER_PERMITTED_KEYS ".ssh/authorized_keys" /* * Per-user and system-wide ssh "rc" files. These files are executed with * /bin/sh before starting the shell or command if they exist. They will be * passed "proto cookie" as arguments if X11 forwarding with spoofing is in * use. xauth will be run if neither of these exists. */ #define SSH_USER_RC ".ssh/rc" #define SSH_SYSTEM_RC ETCDIR "/sshrc" /* * Ssh-only version of /etc/hosts.equiv. Additionally, the daemon may use * ~/.rhosts and /etc/hosts.equiv if rhosts authentication is enabled. */ #define SSH_HOSTS_EQUIV ETCDIR "/shosts.equiv" /* * Name of the environment variable containing the pathname of the * authentication socket. */ #define SSH_AUTHSOCKET_ENV_NAME "SSH_AUTH_SOCK" /* * Name of the environment variable containing the pathname of the * authentication socket. */ #define SSH_AGENTPID_ENV_NAME "SSH_AGENT_PID" /* * Default path to ssh-askpass used by ssh-add, * environment variable for overwriting the default location */ #define SSH_ASKPASS_DEFAULT "/usr/X11R6/bin/ssh-askpass" #define SSH_ASKPASS_ENV "SSH_ASKPASS" /* * Force host key length and server key length to differ by at least this * many bits. This is to make double encryption with rsaref work. */ #define SSH_KEY_BITS_RESERVED 128 /* * Length of the session key in bytes. (Specified as 256 bits in the * protocol.) */ #define SSH_SESSION_KEY_LENGTH 32 /* Name of Kerberos service for SSH to use. */ #define KRB4_SERVICE_NAME "rcmd" /* * Authentication methods. New types can be added, but old types should not * be removed for compatibility. The maximum allowed value is 31. */ #define SSH_AUTH_RHOSTS 1 #define SSH_AUTH_RSA 2 #define SSH_AUTH_PASSWORD 3 #define SSH_AUTH_RHOSTS_RSA 4 #define SSH_AUTH_TIS 5 #define SSH_AUTH_KERBEROS 6 #define SSH_PASS_KERBEROS_TGT 7 /* 8 to 15 are reserved */ #define SSH_PASS_AFS_TOKEN 21 /* Protocol flags. These are bit masks. */ #define SSH_PROTOFLAG_SCREEN_NUMBER 1 /* X11 forwarding includes screen */ #define SSH_PROTOFLAG_HOST_IN_FWD_OPEN 2 /* forwarding opens contain host */ /* * Definition of message types. New values can be added, but old values * should not be removed or without careful consideration of the consequences * for compatibility. The maximum value is 254; value 255 is reserved for * future extension. */ /* Message name */ /* msg code */ /* arguments */ #define SSH_MSG_NONE 0 /* no message */ #define SSH_MSG_DISCONNECT 1 /* cause (string) */ #define SSH_SMSG_PUBLIC_KEY 2 /* ck,msk,srvk,hostk */ #define SSH_CMSG_SESSION_KEY 3 /* key (BIGNUM) */ #define SSH_CMSG_USER 4 /* user (string) */ #define SSH_CMSG_AUTH_RHOSTS 5 /* user (string) */ #define SSH_CMSG_AUTH_RSA 6 /* modulus (BIGNUM) */ #define SSH_SMSG_AUTH_RSA_CHALLENGE 7 /* int (BIGNUM) */ #define SSH_CMSG_AUTH_RSA_RESPONSE 8 /* int (BIGNUM) */ #define SSH_CMSG_AUTH_PASSWORD 9 /* pass (string) */ #define SSH_CMSG_REQUEST_PTY 10 /* TERM, tty modes */ #define SSH_CMSG_WINDOW_SIZE 11 /* row,col,xpix,ypix */ #define SSH_CMSG_EXEC_SHELL 12 /* */ #define SSH_CMSG_EXEC_CMD 13 /* cmd (string) */ #define SSH_SMSG_SUCCESS 14 /* */ #define SSH_SMSG_FAILURE 15 /* */ #define SSH_CMSG_STDIN_DATA 16 /* data (string) */ #define SSH_SMSG_STDOUT_DATA 17 /* data (string) */ #define SSH_SMSG_STDERR_DATA 18 /* data (string) */ #define SSH_CMSG_EOF 19 /* */ #define SSH_SMSG_EXITSTATUS 20 /* status (int) */ #define SSH_MSG_CHANNEL_OPEN_CONFIRMATION 21 /* channel (int) */ #define SSH_MSG_CHANNEL_OPEN_FAILURE 22 /* channel (int) */ #define SSH_MSG_CHANNEL_DATA 23 /* ch,data (int,str) */ #define SSH_MSG_CHANNEL_CLOSE 24 /* channel (int) */ #define SSH_MSG_CHANNEL_CLOSE_CONFIRMATION 25 /* channel (int) */ /* SSH_CMSG_X11_REQUEST_FORWARDING 26 OBSOLETE */ #define SSH_SMSG_X11_OPEN 27 /* channel (int) */ #define SSH_CMSG_PORT_FORWARD_REQUEST 28 /* p,host,hp (i,s,i) */ #define SSH_MSG_PORT_OPEN 29 /* ch,h,p (i,s,i) */ #define SSH_CMSG_AGENT_REQUEST_FORWARDING 30 /* */ #define SSH_SMSG_AGENT_OPEN 31 /* port (int) */ #define SSH_MSG_IGNORE 32 /* string */ #define SSH_CMSG_EXIT_CONFIRMATION 33 /* */ #define SSH_CMSG_X11_REQUEST_FORWARDING 34 /* proto,data (s,s) */ #define SSH_CMSG_AUTH_RHOSTS_RSA 35 /* user,mod (s,mpi) */ #define SSH_MSG_DEBUG 36 /* string */ #define SSH_CMSG_REQUEST_COMPRESSION 37 /* level 1-9 (int) */ #define SSH_CMSG_MAX_PACKET_SIZE 38 /* size 4k-1024k (int) */ #define SSH_CMSG_AUTH_TIS 39 /* we use this for s/key */ #define SSH_SMSG_AUTH_TIS_CHALLENGE 40 /* challenge (string) */ #define SSH_CMSG_AUTH_TIS_RESPONSE 41 /* response (string) */ #define SSH_CMSG_AUTH_KERBEROS 42 /* (KTEXT) */ #define SSH_SMSG_AUTH_KERBEROS_RESPONSE 43 /* (KTEXT) */ #define SSH_CMSG_HAVE_KERBEROS_TGT 44 /* credentials (s) */ #define SSH_CMSG_HAVE_AFS_TOKEN 65 /* token (s) */ /*------------ definitions for login.c -------------*/ /* * Returns the time when the user last logged in. Returns 0 if the * information is not available. This must be called before record_login. * The host from which the user logged in is stored in buf. */ unsigned long get_last_login_time(uid_t uid, const char *logname, char *buf, unsigned int bufsize); /* * Records that the user has logged in. This does many things normally done * by login(1). */ void record_login(int pid, const char *ttyname, const char *user, uid_t uid, const char *host, struct sockaddr_in * addr); /* * Records that the user has logged out. This does many thigs normally done * by login(1) or init. */ void record_logout(int pid, const char *ttyname); /*------------ definitions for sshconnect.c ----------*/ /* * Opens a TCP/IP connection to the remote server on the given host. If port * is 0, the default port will be used. If anonymous is zero, a privileged * port will be allocated to make the connection. This requires super-user * privileges if anonymous is false. Connection_attempts specifies the * maximum number of tries, one per second. This returns true on success, * and zero on failure. If the connection is successful, this calls * packet_set_connection for the connection. */ int ssh_connect(const char *host, struct sockaddr_in * hostaddr, u_short port, int connection_attempts, int anonymous, uid_t original_real_uid, const char *proxy_command); /* * Starts a dialog with the server, and authenticates the current user on the * server. This does not need any extra privileges. The basic connection to * the server must already have been established before this is called. If * login fails, this function prints an error and never returns. This * initializes the random state, and leaves it initialized (it will also have * references from the packet module). */ void ssh_login(int host_key_valid, RSA * host_key, const char *host, struct sockaddr_in * hostaddr, uid_t original_real_uid); /*------------ Definitions for various authentication methods. -------*/ /* * Tries to authenticate the user using the .rhosts file. Returns true if * authentication succeeds. If ignore_rhosts is non-zero, this will not * consider .rhosts and .shosts (/etc/hosts.equiv will still be used). */ int auth_rhosts(struct passwd * pw, const char *client_user); /* * Tries to authenticate the user using the .rhosts file and the host using * its host key. Returns true if authentication succeeds. */ int auth_rhosts_rsa(struct passwd * pw, const char *client_user, BIGNUM * client_host_key_e, BIGNUM * client_host_key_n); /* * Tries to authenticate the user using password. Returns true if * authentication succeeds. */ int auth_password(struct passwd * pw, const char *password); /* * Performs the RSA authentication dialog with the client. This returns 0 if * the client could not be authenticated, and 1 if authentication was * successful. This may exit if there is a serious protocol violation. */ int auth_rsa(struct passwd * pw, BIGNUM * client_n); /* * Parses an RSA key (number of bits, e, n) from a string. Moves the pointer * over the key. Skips any whitespace at the beginning and at end. */ int auth_rsa_read_key(char **cpp, unsigned int *bitsp, BIGNUM * e, BIGNUM * n); /* * Returns the name of the machine at the other end of the socket. The * returned string should be freed by the caller. */ char *get_remote_hostname(int socket); /* * Return the canonical name of the host in the other side of the current * connection (as returned by packet_get_connection). The host name is * cached, so it is efficient to call this several times. */ const char *get_canonical_hostname(void); /* * Returns the remote IP address as an ascii string. The value need not be * freed by the caller. */ const char *get_remote_ipaddr(void); /* Returns the port number of the peer of the socket. */ int get_peer_port(int sock); /* Returns the port number of the remote host. */ int get_remote_port(void); /* * Tries to match the host name (which must be in all lowercase) against the * comma-separated sequence of subpatterns (each possibly preceded by ! to * indicate negation). Returns true if there is a positive match; zero * otherwise. */ int match_hostname(const char *host, const char *pattern, unsigned int len); /* * Checks whether the given host is already in the list of our known hosts. * Returns HOST_OK if the host is known and has the specified key, HOST_NEW * if the host is not known, and HOST_CHANGED if the host is known but used * to have a different host key. The host must be in all lowercase. */ typedef enum { HOST_OK, HOST_NEW, HOST_CHANGED } HostStatus; HostStatus check_host_in_hostfile(const char *filename, const char *host, BIGNUM * e, BIGNUM * n, BIGNUM * ke, BIGNUM * kn); /* * Appends an entry to the host file. Returns false if the entry could not * be appended. */ int add_host_to_hostfile(const char *filename, const char *host, BIGNUM * e, BIGNUM * n); /* * Performs the RSA authentication challenge-response dialog with the client, * and returns true (non-zero) if the client gave the correct answer to our * challenge; returns zero if the client gives a wrong answer. */ int auth_rsa_challenge_dialog(BIGNUM * e, BIGNUM * n); /* * Reads a passphrase from /dev/tty with echo turned off. Returns the * passphrase (allocated with xmalloc). Exits if EOF is encountered. If * from_stdin is true, the passphrase will be read from stdin instead. */ char *read_passphrase(const char *prompt, int from_stdin); /* * Saves the authentication (private) key in a file, encrypting it with * passphrase. The identification of the file (lowest 64 bits of n) will * precede the key to provide identification of the key without needing a * passphrase. */ int save_private_key(const char *filename, const char *passphrase, RSA * private_key, const char *comment); /* * Loads the public part of the key file (public key and comment). Returns 0 * if an error occurred; zero if the public key was successfully read. The * comment of the key is returned in comment_return if it is non-NULL; the * caller must free the value with xfree. */ int load_public_key(const char *filename, RSA * pub, char **comment_return); /* * Loads the private key from the file. Returns 0 if an error is encountered * (file does not exist or is not readable, or passphrase is bad). This * initializes the private key. The comment of the key is returned in * comment_return if it is non-NULL; the caller must free the value with * xfree. */ int load_private_key(const char *filename, const char *passphrase, RSA * private_key, char **comment_return); /*------------ Definitions for logging. -----------------------*/ /* Supported syslog facilities and levels. */ typedef enum { SYSLOG_FACILITY_DAEMON, SYSLOG_FACILITY_USER, SYSLOG_FACILITY_AUTH, SYSLOG_FACILITY_LOCAL0, SYSLOG_FACILITY_LOCAL1, SYSLOG_FACILITY_LOCAL2, SYSLOG_FACILITY_LOCAL3, SYSLOG_FACILITY_LOCAL4, SYSLOG_FACILITY_LOCAL5, SYSLOG_FACILITY_LOCAL6, SYSLOG_FACILITY_LOCAL7 } SyslogFacility; typedef enum { SYSLOG_LEVEL_QUIET, SYSLOG_LEVEL_FATAL, SYSLOG_LEVEL_ERROR, SYSLOG_LEVEL_INFO, SYSLOG_LEVEL_VERBOSE, SYSLOG_LEVEL_DEBUG } LogLevel; /* Initializes logging. */ void log_init(char *av0, LogLevel level, SyslogFacility facility, int on_stderr); /* Logging implementation, depending on server or client */ void do_log(LogLevel level, const char *fmt, va_list args); /* name to facility/level */ SyslogFacility log_facility_number(char *name); LogLevel log_level_number(char *name); /* Output a message to syslog or stderr */ void fatal(const char *fmt,...) __attribute__((format(printf, 1, 2))); void error(const char *fmt,...) __attribute__((format(printf, 1, 2))); void log(const char *fmt,...) __attribute__((format(printf, 1, 2))); void verbose(const char *fmt,...) __attribute__((format(printf, 1, 2))); void debug(const char *fmt,...) __attribute__((format(printf, 1, 2))); /* same as fatal() but w/o logging */ void fatal_cleanup(void); /* * Registers a cleanup function to be called by fatal()/fatal_cleanup() * before exiting. It is permissible to call fatal_remove_cleanup for the * function itself from the function. */ void fatal_add_cleanup(void (*proc) (void *context), void *context); /* Removes a cleanup function to be called at fatal(). */ void fatal_remove_cleanup(void (*proc) (void *context), void *context); /*---------------- definitions for channels ------------------*/ /* Sets specific protocol options. */ void channel_set_options(int hostname_in_open); /* * Allocate a new channel object and set its type and socket. Remote_name * must have been allocated with xmalloc; this will free it when the channel * is freed. */ int channel_allocate(int type, int sock, char *remote_name); /* Free the channel and close its socket. */ void channel_free(int channel); /* Add any bits relevant to channels in select bitmasks. */ void channel_prepare_select(fd_set * readset, fd_set * writeset); /* * After select, perform any appropriate operations for channels which have * events pending. */ void channel_after_select(fd_set * readset, fd_set * writeset); /* If there is data to send to the connection, send some of it now. */ void channel_output_poll(void); /* * This is called when a packet of type CHANNEL_DATA has just been received. * The message type has already been consumed, but channel number and data is * still there. */ void channel_input_data(int payload_len); /* Returns true if no channel has too much buffered data. */ int channel_not_very_much_buffered_data(void); /* This is called after receiving CHANNEL_CLOSE. */ void channel_input_close(void); /* This is called after receiving CHANNEL_CLOSE_CONFIRMATION. */ void channel_input_close_confirmation(void); /* This is called after receiving CHANNEL_OPEN_CONFIRMATION. */ void channel_input_open_confirmation(void); /* This is called after receiving CHANNEL_OPEN_FAILURE from the other side. */ void channel_input_open_failure(void); /* This closes any sockets that are listening for connections; this removes any unix domain sockets. */ void channel_stop_listening(void); /* * Closes the sockets of all channels. This is used to close extra file * descriptors after a fork. */ void channel_close_all(void); /* Returns the maximum file descriptor number used by the channels. */ int channel_max_fd(void); /* Returns true if there is still an open channel over the connection. */ int channel_still_open(void); /* * Returns a string containing a list of all open channels. The list is * suitable for displaying to the user. It uses crlf instead of newlines. * The caller should free the string with xfree. */ char *channel_open_message(void); /* * Initiate forwarding of connections to local port "port" through the secure * channel to host:port from remote side. This never returns if there was an * error. */ void channel_request_local_forwarding(u_short port, const char *host, u_short remote_port); /* * Initiate forwarding of connections to port "port" on remote host through * the secure channel to host:port from local side. This never returns if * there was an error. This registers that open requests for that port are * permitted. */ void channel_request_remote_forwarding(u_short port, const char *host, u_short remote_port); /* * Permits opening to any host/port in SSH_MSG_PORT_OPEN. This is usually * called by the server, because the user could connect to any port anyway, * and the server has no way to know but to trust the client anyway. */ void channel_permit_all_opens(void); /* * This is called after receiving CHANNEL_FORWARDING_REQUEST. This initates * listening for the port, and sends back a success reply (or disconnect * message if there was an error). This never returns if there was an error. */ void channel_input_port_forward_request(int is_root); /* * This is called after receiving PORT_OPEN message. This attempts to * connect to the given host:port, and sends back CHANNEL_OPEN_CONFIRMATION * or CHANNEL_OPEN_FAILURE. */ void channel_input_port_open(int payload_len); /* * Creates a port for X11 connections, and starts listening for it. Returns * the display name, or NULL if an error was encountered. */ char *x11_create_display(int screen); /* * Creates an internet domain socket for listening for X11 connections. * Returns a suitable value for the DISPLAY variable, or NULL if an error * occurs. */ char *x11_create_display_inet(int screen); /* * This is called when SSH_SMSG_X11_OPEN is received. The packet contains * the remote channel number. We should do whatever we want, and respond * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE. */ void x11_input_open(int payload_len); /* * Requests forwarding of X11 connections. This should be called on the * client only. */ void x11_request_forwarding(void); /* * Requests forwarding for X11 connections, with authentication spoofing. * This should be called in the client only. */ void x11_request_forwarding_with_spoofing(const char *proto, const char *data); /* Sends a message to the server to request authentication fd forwarding. */ void auth_request_forwarding(void); /* * Returns the name of the forwarded authentication socket. Returns NULL if * there is no forwarded authentication socket. The returned value points to * a static buffer. */ char *auth_get_socket_name(void); /* * This if called to process SSH_CMSG_AGENT_REQUEST_FORWARDING on the server. * This starts forwarding authentication requests. */ void auth_input_request_forwarding(struct passwd * pw); /* This is called to process an SSH_SMSG_AGENT_OPEN message. */ void auth_input_open_request(void); /* * Returns true if the given string matches the pattern (which may contain ? * and * as wildcards), and zero if it does not match. */ int match_pattern(const char *s, const char *pattern); /* * Expands tildes in the file name. Returns data allocated by xmalloc. * Warning: this calls getpw*. */ char *tilde_expand_filename(const char *filename, uid_t my_uid); /* * Performs the interactive session. This handles data transmission between * the client and the program. Note that the notion of stdin, stdout, and * stderr in this function is sort of reversed: this function writes to stdin * (of the child program), and reads from stdout and stderr (of the child * program). */ void server_loop(int pid, int fdin, int fdout, int fderr); /* Client side main loop for the interactive session. */ int client_loop(int have_pty, int escape_char); /* Linked list of custom environment strings (see auth-rsa.c). */ struct envstring { struct envstring *next; char *s; }; /* * Ensure all of data on socket comes through. f==read || f==write */ int atomicio(int (*f)(), int fd, void *s, size_t n); #ifdef KRB4 #include /* * Performs Kerberos v4 mutual authentication with the client. This returns 0 * if the client could not be authenticated, and 1 if authentication was * successful. This may exit if there is a serious protocol violation. */ int auth_krb4(const char *server_user, KTEXT auth, char **client); int krb4_init(uid_t uid); void krb4_cleanup_proc(void *ignore); int auth_krb4_password(struct passwd * pw, const char *password); #ifdef AFS #include /* Accept passed Kerberos v4 ticket-granting ticket and AFS tokens. */ int auth_kerberos_tgt(struct passwd * pw, const char *string); int auth_afs_token(struct passwd * pw, const char *token_string); int creds_to_radix(CREDENTIALS * creds, unsigned char *buf); int radix_to_creds(const char *buf, CREDENTIALS * creds); #endif /* AFS */ #endif /* KRB4 */ #ifdef SKEY #include char *skey_fake_keyinfo(char *username); int auth_skey_password(struct passwd * pw, const char *password); #endif /* SKEY */ #endif /* SSH_H */