5 Author: Tatu Ylonen <ylo@cs.hut.fi>
7 Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
10 Created: Fri Mar 17 17:09:37 1995 ylo
12 Generic header file for ssh.
21 #include <netinet/in.h> /* For struct sockaddr_in */
22 #include <pwd.h> /* For struct pw */
23 #include <stdarg.h> /* For va_list */
28 /* The default cipher used if IDEA is not supported by the remote host.
29 It is recommended that this be one of the mandatory ciphers (DES, 3DES),
30 though that is not required. */
31 #define SSH_FALLBACK_CIPHER SSH_CIPHER_3DES
33 /* Cipher used for encrypting authentication files. */
34 #define SSH_AUTHFILE_CIPHER SSH_CIPHER_3DES
36 /* Default port number. */
37 #define SSH_DEFAULT_PORT 22
39 /* Maximum number of TCP/IP ports forwarded per direction. */
40 #define SSH_MAX_FORWARDS_PER_DIRECTION 100
42 /* Maximum number of RSA authentication identity files that can be specified
43 in configuration files or on the command line. */
44 #define SSH_MAX_IDENTITY_FILES 100
46 /* Major protocol version. Different version indicates major incompatiblity
47 that prevents communication. */
48 #define PROTOCOL_MAJOR 1
50 /* Minor protocol version. Different version indicates minor incompatibility
51 that does not prevent interoperation. */
52 #define PROTOCOL_MINOR 5
54 /* Name for the service. The port named by this service overrides the default
56 #define SSH_SERVICE_NAME "ssh"
62 #define PIDDIR "/var/run"
64 /* System-wide file containing host keys of known hosts. This file should be
66 #define SSH_SYSTEM_HOSTFILE ETCDIR "/ssh_known_hosts"
68 /* HOST_KEY_FILE /etc/ssh_host_key,
69 SERVER_CONFIG_FILE /etc/sshd_config,
70 and HOST_CONFIG_FILE /etc/ssh_config
71 are all defined in Makefile.in. Of these, ssh_host_key should be readable
72 only by root, whereas ssh_config should be world-readable. */
74 #define HOST_KEY_FILE ETCDIR "/ssh_host_key"
75 #define SERVER_CONFIG_FILE ETCDIR "/sshd_config"
76 #define HOST_CONFIG_FILE ETCDIR "/ssh_config"
79 #define SSH_PROGRAM "/usr/bin/ssh"
80 #endif /* SSH_PROGRAM */
83 #define LOGIN_PROGRAM "/usr/bin/login"
84 #endif /* LOGIN_PROGRAM */
86 #ifndef ASKPASS_PROGRAM
87 #define ASKPASS_PROGRAM "/usr/lib/ssh/ssh-askpass"
88 #endif /* ASKPASS_PROGRAM */
90 /* The process id of the daemon listening for connections is saved
91 here to make it easier to kill the correct daemon when necessary. */
92 #define SSH_DAEMON_PID_FILE PIDDIR "/sshd.pid"
94 /* The directory in user\'s home directory in which the files reside.
95 The directory should be world-readable (though not all files are). */
96 #define SSH_USER_DIR ".ssh"
98 /* Per-user file containing host keys of known hosts. This file need
99 not be readable by anyone except the user him/herself, though this does
100 not contain anything particularly secret. */
101 #define SSH_USER_HOSTFILE "~/.ssh/known_hosts"
103 /* Name of the default file containing client-side authentication key.
104 This file should only be readable by the user him/herself. */
105 #define SSH_CLIENT_IDENTITY ".ssh/identity"
107 /* Configuration file in user\'s home directory. This file need not be
108 readable by anyone but the user him/herself, but does not contain
109 anything particularly secret. If the user\'s home directory resides
110 on an NFS volume where root is mapped to nobody, this may need to be
112 #define SSH_USER_CONFFILE ".ssh/config"
114 /* File containing a list of those rsa keys that permit logging in as
115 this user. This file need not be
116 readable by anyone but the user him/herself, but does not contain
117 anything particularly secret. If the user\'s home directory resides
118 on an NFS volume where root is mapped to nobody, this may need to be
119 world-readable. (This file is read by the daemon which is running as
121 #define SSH_USER_PERMITTED_KEYS ".ssh/authorized_keys"
123 /* Per-user and system-wide ssh "rc" files. These files are executed with
124 /bin/sh before starting the shell or command if they exist. They
125 will be passed "proto cookie" as arguments if X11 forwarding with
126 spoofing is in use. xauth will be run if neither of these exists. */
127 #define SSH_USER_RC ".ssh/rc"
128 #define SSH_SYSTEM_RC ETCDIR "/sshrc"
130 /* Ssh-only version of /etc/hosts.equiv. */
131 #define SSH_HOSTS_EQUIV ETCDIR "/shosts.equiv"
133 /* Additionally, the daemon may use ~/.rhosts and /etc/hosts.equiv if
134 rhosts authentication is enabled. */
136 /* Name of the environment variable containing the pathname of the
137 authentication socket. */
138 #define SSH_AUTHSOCKET_ENV_NAME "SSH_AUTH_SOCK"
140 /* Name of the environment variable containing the pathname of the
141 authentication socket. */
142 #define SSH_AGENTPID_ENV_NAME "SSH_AGENT_PID"
144 /* Force host key length and server key length to differ by at least this
145 many bits. This is to make double encryption with rsaref work. */
146 #define SSH_KEY_BITS_RESERVED 128
148 /* Length of the session key in bytes. (Specified as 256 bits in the
150 #define SSH_SESSION_KEY_LENGTH 32
152 /* Name of Kerberos service for SSH to use. */
153 #define KRB4_SERVICE_NAME "rcmd"
155 /* Authentication methods. New types can be added, but old types should not
156 be removed for compatibility. The maximum allowed value is 31. */
157 #define SSH_AUTH_RHOSTS 1
158 #define SSH_AUTH_RSA 2
159 #define SSH_AUTH_PASSWORD 3
160 #define SSH_AUTH_RHOSTS_RSA 4
162 #define SSH_AUTH_KERBEROS 6
163 #define SSH_PASS_KERBEROS_TGT 7
164 /* 8 to 15 are reserved */
165 #define SSH_PASS_AFS_TOKEN 21
167 /* Protocol flags. These are bit masks. */
168 #define SSH_PROTOFLAG_SCREEN_NUMBER 1 /* X11 forwarding includes screen */
169 #define SSH_PROTOFLAG_HOST_IN_FWD_OPEN 2 /* forwarding opens contain host */
171 /* Definition of message types. New values can be added, but old values
172 should not be removed or without careful consideration of the consequences
173 for compatibility. The maximum value is 254; value 255 is reserved
174 for future extension. */
175 /* Message name */ /* msg code */ /* arguments */
176 #define SSH_MSG_NONE 0 /* no message */
177 #define SSH_MSG_DISCONNECT 1 /* cause (string) */
178 #define SSH_SMSG_PUBLIC_KEY 2 /* ck,msk,srvk,hostk */
179 #define SSH_CMSG_SESSION_KEY 3 /* key (BIGNUM) */
180 #define SSH_CMSG_USER 4 /* user (string) */
181 #define SSH_CMSG_AUTH_RHOSTS 5 /* user (string) */
182 #define SSH_CMSG_AUTH_RSA 6 /* modulus (BIGNUM) */
183 #define SSH_SMSG_AUTH_RSA_CHALLENGE 7 /* int (BIGNUM) */
184 #define SSH_CMSG_AUTH_RSA_RESPONSE 8 /* int (BIGNUM) */
185 #define SSH_CMSG_AUTH_PASSWORD 9 /* pass (string) */
186 #define SSH_CMSG_REQUEST_PTY 10 /* TERM, tty modes */
187 #define SSH_CMSG_WINDOW_SIZE 11 /* row,col,xpix,ypix */
188 #define SSH_CMSG_EXEC_SHELL 12 /* */
189 #define SSH_CMSG_EXEC_CMD 13 /* cmd (string) */
190 #define SSH_SMSG_SUCCESS 14 /* */
191 #define SSH_SMSG_FAILURE 15 /* */
192 #define SSH_CMSG_STDIN_DATA 16 /* data (string) */
193 #define SSH_SMSG_STDOUT_DATA 17 /* data (string) */
194 #define SSH_SMSG_STDERR_DATA 18 /* data (string) */
195 #define SSH_CMSG_EOF 19 /* */
196 #define SSH_SMSG_EXITSTATUS 20 /* status (int) */
197 #define SSH_MSG_CHANNEL_OPEN_CONFIRMATION 21 /* channel (int) */
198 #define SSH_MSG_CHANNEL_OPEN_FAILURE 22 /* channel (int) */
199 #define SSH_MSG_CHANNEL_DATA 23 /* ch,data (int,str) */
200 #define SSH_MSG_CHANNEL_CLOSE 24 /* channel (int) */
201 #define SSH_MSG_CHANNEL_CLOSE_CONFIRMATION 25 /* channel (int) */
202 /* SSH_CMSG_X11_REQUEST_FORWARDING 26 OBSOLETE */
203 #define SSH_SMSG_X11_OPEN 27 /* channel (int) */
204 #define SSH_CMSG_PORT_FORWARD_REQUEST 28 /* p,host,hp (i,s,i) */
205 #define SSH_MSG_PORT_OPEN 29 /* ch,h,p (i,s,i) */
206 #define SSH_CMSG_AGENT_REQUEST_FORWARDING 30 /* */
207 #define SSH_SMSG_AGENT_OPEN 31 /* port (int) */
208 #define SSH_MSG_IGNORE 32 /* string */
209 #define SSH_CMSG_EXIT_CONFIRMATION 33 /* */
210 #define SSH_CMSG_X11_REQUEST_FORWARDING 34 /* proto,data (s,s) */
211 #define SSH_CMSG_AUTH_RHOSTS_RSA 35 /* user,mod (s,mpi) */
212 #define SSH_MSG_DEBUG 36 /* string */
213 #define SSH_CMSG_REQUEST_COMPRESSION 37 /* level 1-9 (int) */
214 #define SSH_CMSG_MAX_PACKET_SIZE 38 /* size 4k-1024k (int) */
215 #define SSH_CMSG_AUTH_TIS 39 /* this is proto-1.5, but we ignore TIS */
216 #define SSH_SMSG_AUTH_TIS_CHALLENGE 40
217 #define SSH_CMSG_AUTH_TIS_RESPONSE 41
219 #define SSH_CMSG_AUTH_KERBEROS 42 /* (KTEXT) */
220 #define SSH_SMSG_AUTH_KERBEROS_RESPONSE 43 /* (KTEXT) */
221 #define SSH_CMSG_HAVE_KERBEROS_TGT 44 /* credentials (s) */
222 #define SSH_CMSG_HAVE_AFS_TOKEN 65 /* token (s) */
224 /*------------ definitions for login.c -------------*/
226 /* Returns the time when the user last logged in. Returns 0 if the
227 information is not available. This must be called before record_login.
228 The host from which the user logged in is stored in buf. */
229 unsigned long get_last_login_time(uid_t uid, const char *logname,
230 char *buf, unsigned int bufsize);
232 /* Records that the user has logged in. This does many things normally
234 void record_login(int pid, const char *ttyname, const char *user, uid_t uid,
235 const char *host, struct sockaddr_in *addr);
237 /* Records that the user has logged out. This does many thigs normally
238 done by login(1) or init. */
239 void record_logout(int pid, const char *ttyname);
241 /*------------ definitions for sshconnect.c ----------*/
243 /* Opens a TCP/IP connection to the remote server on the given host. If
244 port is 0, the default port will be used. If anonymous is zero,
245 a privileged port will be allocated to make the connection.
246 This requires super-user privileges if anonymous is false.
247 Connection_attempts specifies the maximum number of tries, one per
248 second. This returns true on success, and zero on failure. If the
249 connection is successful, this calls packet_set_connection for the
251 int ssh_connect(const char *host, struct sockaddr_in *hostaddr,
252 int port, int connection_attempts,
253 int anonymous, uid_t original_real_uid,
254 const char *proxy_command);
256 /* Starts a dialog with the server, and authenticates the current user on the
257 server. This does not need any extra privileges. The basic connection
258 to the server must already have been established before this is called.
259 If login fails, this function prints an error and never returns.
260 This initializes the random state, and leaves it initialized (it will also
261 have references from the packet module). */
263 void ssh_login(int host_key_valid, RSA *host_key, const char *host,
264 struct sockaddr_in *hostaddr, uid_t original_real_uid);
266 /*------------ Definitions for various authentication methods. -------*/
268 /* Tries to authenticate the user using the .rhosts file. Returns true if
269 authentication succeeds. If ignore_rhosts is non-zero, this will not
270 consider .rhosts and .shosts (/etc/hosts.equiv will still be used). */
271 int auth_rhosts(struct passwd *pw, const char *client_user);
273 /* Tries to authenticate the user using the .rhosts file and the host using
274 its host key. Returns true if authentication succeeds. */
275 int auth_rhosts_rsa(struct passwd *pw, const char *client_user,
276 BIGNUM *client_host_key_e, BIGNUM *client_host_key_n);
278 /* Tries to authenticate the user using password. Returns true if
279 authentication succeeds. */
280 int auth_password(struct passwd *pw, const char *password);
282 /* Performs the RSA authentication dialog with the client. This returns
283 0 if the client could not be authenticated, and 1 if authentication was
284 successful. This may exit if there is a serious protocol violation. */
285 int auth_rsa(struct passwd *pw, BIGNUM *client_n);
287 /* Parses an RSA key (number of bits, e, n) from a string. Moves the pointer
288 over the key. Skips any whitespace at the beginning and at end. */
289 int auth_rsa_read_key(char **cpp, unsigned int *bitsp, BIGNUM *e, BIGNUM *n);
291 /* Returns the name of the machine at the other end of the socket. The
292 returned string should be freed by the caller. */
293 char *get_remote_hostname(int socket);
295 /* Return the canonical name of the host in the other side of the current
296 connection (as returned by packet_get_connection). The host name is
297 cached, so it is efficient to call this several times. */
298 const char *get_canonical_hostname(void);
300 /* Returns the remote IP address as an ascii string. The value need not be
301 freed by the caller. */
302 const char *get_remote_ipaddr(void);
304 /* Returns the port number of the peer of the socket. */
305 int get_peer_port(int sock);
307 /* Returns the port number of the remote host. */
308 int get_remote_port(void);
310 /* Tries to match the host name (which must be in all lowercase) against the
311 comma-separated sequence of subpatterns (each possibly preceded by ! to
312 indicate negation). Returns true if there is a positive match; zero
314 int match_hostname(const char *host, const char *pattern, unsigned int len);
316 /* Checks whether the given host is already in the list of our known hosts.
317 Returns HOST_OK if the host is known and has the specified key,
318 HOST_NEW if the host is not known, and HOST_CHANGED if the host is known
319 but used to have a different host key. The host must be in all lowercase. */
320 typedef enum { HOST_OK, HOST_NEW, HOST_CHANGED } HostStatus;
321 HostStatus check_host_in_hostfile(const char *filename, const char *host,
322 BIGNUM *e, BIGNUM *n, BIGNUM *ke, BIGNUM *kn);
324 /* Appends an entry to the host file. Returns false if the entry
325 could not be appended. */
326 int add_host_to_hostfile(const char *filename, const char *host,
327 BIGNUM *e, BIGNUM *n);
329 /* Performs the RSA authentication challenge-response dialog with the client,
330 and returns true (non-zero) if the client gave the correct answer to
331 our challenge; returns zero if the client gives a wrong answer. */
332 int auth_rsa_challenge_dialog(BIGNUM *e, BIGNUM *n);
334 /* Reads a passphrase from /dev/tty with echo turned off. Returns the
335 passphrase (allocated with xmalloc). Exits if EOF is encountered.
336 If from_stdin is true, the passphrase will be read from stdin instead. */
337 char *read_passphrase(const char *prompt, int from_stdin);
339 /* Saves the authentication (private) key in a file, encrypting it with
340 passphrase. The identification of the file (lowest 64 bits of n)
341 will precede the key to provide identification of the key without
342 needing a passphrase. */
343 int save_private_key(const char *filename, const char *passphrase,
344 RSA *private_key, const char *comment);
346 /* Loads the public part of the key file (public key and comment).
347 Returns 0 if an error occurred; zero if the public key was successfully
348 read. The comment of the key is returned in comment_return if it is
349 non-NULL; the caller must free the value with xfree. */
350 int load_public_key(const char *filename, RSA *pub,
351 char **comment_return);
353 /* Loads the private key from the file. Returns 0 if an error is encountered
354 (file does not exist or is not readable, or passphrase is bad).
355 This initializes the private key. The comment of the key is returned
356 in comment_return if it is non-NULL; the caller must free the value
358 int load_private_key(const char *filename, const char *passphrase,
359 RSA *private_key, char **comment_return);
361 /*------------ Definitions for logging. -----------------------*/
363 /* Supported syslog facilities and levels. */
366 SYSLOG_FACILITY_DAEMON,
367 SYSLOG_FACILITY_USER,
368 SYSLOG_FACILITY_AUTH,
369 SYSLOG_FACILITY_LOCAL0,
370 SYSLOG_FACILITY_LOCAL1,
371 SYSLOG_FACILITY_LOCAL2,
372 SYSLOG_FACILITY_LOCAL3,
373 SYSLOG_FACILITY_LOCAL4,
374 SYSLOG_FACILITY_LOCAL5,
375 SYSLOG_FACILITY_LOCAL6,
376 SYSLOG_FACILITY_LOCAL7
389 /* Initializes logging. */
390 void log_init(char *av0, LogLevel level, SyslogFacility facility, int on_stderr);
392 /* Logging implementation, depending on server or client */
393 void do_log(LogLevel level, const char *fmt, va_list args);
395 /* Output a message to syslog or stderr */
396 void fatal(const char *fmt, ...);
397 void error(const char *fmt, ...);
398 void log(const char *fmt, ...);
399 void chat(const char *fmt, ...);
400 void debug(const char *fmt, ...);
402 /* same as fatal() but w/o logging */
403 void fatal_cleanup(void);
405 /* Registers a cleanup function to be called by fatal()/fatal_cleanup() before exiting.
406 It is permissible to call fatal_remove_cleanup for the function itself
407 from the function. */
408 void fatal_add_cleanup(void (*proc)(void *context), void *context);
410 /* Removes a cleanup function to be called at fatal(). */
411 void fatal_remove_cleanup(void (*proc)(void *context), void *context);
413 /*---------------- definitions for channels ------------------*/
415 /* Sets specific protocol options. */
416 void channel_set_options(int hostname_in_open);
418 /* Allocate a new channel object and set its type and socket. Remote_name
419 must have been allocated with xmalloc; this will free it when the channel
421 int channel_allocate(int type, int sock, char *remote_name);
423 /* Free the channel and close its socket. */
424 void channel_free(int channel);
426 /* Add any bits relevant to channels in select bitmasks. */
427 void channel_prepare_select(fd_set *readset, fd_set *writeset);
429 /* After select, perform any appropriate operations for channels which
430 have events pending. */
431 void channel_after_select(fd_set *readset, fd_set *writeset);
433 /* If there is data to send to the connection, send some of it now. */
434 void channel_output_poll(void);
436 /* This is called when a packet of type CHANNEL_DATA has just been received.
437 The message type has already been consumed, but channel number and data
439 void channel_input_data(int payload_len);
441 /* Returns true if no channel has too much buffered data. */
442 int channel_not_very_much_buffered_data(void);
444 /* This is called after receiving CHANNEL_CLOSE. */
445 void channel_input_close(void);
447 /* This is called after receiving CHANNEL_CLOSE_CONFIRMATION. */
448 void channel_input_close_confirmation(void);
450 /* This is called after receiving CHANNEL_OPEN_CONFIRMATION. */
451 void channel_input_open_confirmation(void);
453 /* This is called after receiving CHANNEL_OPEN_FAILURE from the other side. */
454 void channel_input_open_failure(void);
456 /* This closes any sockets that are listening for connections; this removes
457 any unix domain sockets. */
458 void channel_stop_listening(void);
460 /* Closes the sockets of all channels. This is used to close extra file
461 descriptors after a fork. */
462 void channel_close_all(void);
464 /* Returns the maximum file descriptor number used by the channels. */
465 int channel_max_fd(void);
467 /* Returns true if there is still an open channel over the connection. */
468 int channel_still_open(void);
470 /* Returns a string containing a list of all open channels. The list is
471 suitable for displaying to the user. It uses crlf instead of newlines.
472 The caller should free the string with xfree. */
473 char *channel_open_message(void);
475 /* Initiate forwarding of connections to local port "port" through the secure
476 channel to host:port from remote side. This never returns if there
478 void channel_request_local_forwarding(int port, const char *host,
481 /* Initiate forwarding of connections to port "port" on remote host through
482 the secure channel to host:port from local side. This never returns
483 if there was an error. This registers that open requests for that
484 port are permitted. */
485 void channel_request_remote_forwarding(int port, const char *host,
488 /* Permits opening to any host/port in SSH_MSG_PORT_OPEN. This is usually
489 called by the server, because the user could connect to any port anyway,
490 and the server has no way to know but to trust the client anyway. */
491 void channel_permit_all_opens(void);
493 /* This is called after receiving CHANNEL_FORWARDING_REQUEST. This initates
494 listening for the port, and sends back a success reply (or disconnect
495 message if there was an error). This never returns if there was an
497 void channel_input_port_forward_request(int is_root);
499 /* This is called after receiving PORT_OPEN message. This attempts to connect
500 to the given host:port, and sends back CHANNEL_OPEN_CONFIRMATION or
501 CHANNEL_OPEN_FAILURE. */
502 void channel_input_port_open(int payload_len);
504 /* Creates a port for X11 connections, and starts listening for it.
505 Returns the display name, or NULL if an error was encountered. */
506 char *x11_create_display(int screen);
508 /* Creates an internet domain socket for listening for X11 connections.
509 Returns a suitable value for the DISPLAY variable, or NULL if an error
511 char *x11_create_display_inet(int screen);
513 /* This is called when SSH_SMSG_X11_OPEN is received. The packet contains
514 the remote channel number. We should do whatever we want, and respond
515 with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE. */
516 void x11_input_open(int payload_len);
518 /* Requests forwarding of X11 connections. This should be called on the
520 void x11_request_forwarding(void);
522 /* Requests forwarding for X11 connections, with authentication spoofing.
523 This should be called in the client only. */
524 void x11_request_forwarding_with_spoofing(const char *proto, const char *data);
526 /* Sends a message to the server to request authentication fd forwarding. */
527 void auth_request_forwarding(void);
529 /* Returns the name of the forwarded authentication socket. Returns NULL
530 if there is no forwarded authentication socket. The returned value points
531 to a static buffer. */
532 char *auth_get_socket_name(void);
534 /* This if called to process SSH_CMSG_AGENT_REQUEST_FORWARDING on the server.
535 This starts forwarding authentication requests. */
536 void auth_input_request_forwarding(struct passwd *pw);
538 /* This is called to process an SSH_SMSG_AGENT_OPEN message. */
539 void auth_input_open_request(void);
541 /* Returns true if the given string matches the pattern (which may contain
542 ? and * as wildcards), and zero if it does not match. */
543 int match_pattern(const char *s, const char *pattern);
545 /* Expands tildes in the file name. Returns data allocated by xmalloc.
546 Warning: this calls getpw*. */
547 char *tilde_expand_filename(const char *filename, uid_t my_uid);
549 /* Performs the interactive session. This handles data transmission between
550 the client and the program. Note that the notion of stdin, stdout, and
551 stderr in this function is sort of reversed: this function writes to
552 stdin (of the child program), and reads from stdout and stderr (of the
554 void server_loop(int pid, int fdin, int fdout, int fderr);
556 /* Client side main loop for the interactive session. */
557 int client_loop(int have_pty, int escape_char);
559 /* Linked list of custom environment strings (see auth-rsa.c). */
561 struct envstring *next;
568 /* Performs Kerberos v4 mutual authentication with the client. This returns
569 0 if the client could not be authenticated, and 1 if authentication was
570 successful. This may exit if there is a serious protocol violation. */
571 int auth_krb4(const char *server_user, KTEXT auth, char **client);
572 int krb4_init(uid_t uid);
573 void krb4_cleanup_proc(void *ignore);
578 /* Accept passed Kerberos v4 ticket-granting ticket and AFS tokens. */
579 int auth_kerberos_tgt(struct passwd *pw, const char *string);
580 int auth_afs_token(struct passwd *pw, const char *token_string);
582 int creds_to_radix(CREDENTIALS *creds, unsigned char *buf);
583 int radix_to_creds(const char *buf, CREDENTIALS *creds);
590 char *skey_fake_keyinfo(char *username);