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openssh/ssh.h
Damien Miller d4a8b7e34d Initial revision
1999-10-27 13:42:43 +10:00

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/*
ssh.h
Author: Tatu Ylonen <ylo@cs.hut.fi>
Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
All rights reserved
Created: Fri Mar 17 17:09:37 1995 ylo
Generic header file for ssh.
*/
/* RCSID("$Id: ssh.h,v 1.1 1999/10/27 03:42:45 damien 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"
#ifndef ETCDIR
#define ETCDIR "/etc"
#endif /* ETCDIR */
#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"
/* HOST_KEY_FILE /etc/ssh_host_key,
SERVER_CONFIG_FILE /etc/sshd_config,
and HOST_CONFIG_FILE /etc/ssh_config
are all defined in Makefile.in. Of these, ssh_host_key should 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. */
#define SSH_HOSTS_EQUIV ETCDIR "/shosts.equiv"
/* Additionally, the daemon may use ~/.rhosts and /etc/hosts.equiv if
rhosts authentication is enabled. */
/* Name of the environment variable containing the pathname of the
authentication socket. */
#define SSH_AUTHSOCKET_ENV_NAME "SSH_AUTH_SOCK"
/* 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
/* 5 is TIS */
#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 /* this is proto-1.5, but we ignore TIS */
#define SSH_SMSG_AUTH_TIS_CHALLENGE 40
#define SSH_CMSG_AUTH_TIS_RESPONSE 41
#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) */
/* Includes that need definitions above. */
#include "readconf.h"
/*------------ 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,
int 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, Options *options,
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).
If strict_modes is true, checks ownership and modes of .rhosts/.shosts. */
int auth_rhosts(struct passwd *pw, const char *client_user,
int ignore_rhosts, int strict_modes);
/* 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,
unsigned int bits, BIGNUM *client_host_key_e,
BIGNUM *client_host_key_n, int ignore_rhosts,
int strict_modes);
/* 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, int strict_modes);
/* 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, unsigned int bits,
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,
unsigned int bits, 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(unsigned int bits, 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. */
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;
/* Initializes logging. If debug is non-zero, debug() will output something.
If quiet is non-zero, none of these will log send anything to syslog
(but maybe to stderr). */
void log_init(char *av0, int on_stderr, int debug, int quiet,
SyslogFacility facility);
/* Outputs a message to syslog or stderr, depending on the implementation.
The format must guarantee that the final message does not exceed 1024
characters. The message should not contain newline. */
void log(const char *fmt, ...);
/* Outputs a message to syslog or stderr, depending on the implementation.
The format must guarantee that the final message does not exceed 1024
characters. The message should not contain newline. */
void debug(const char *fmt, ...);
/* Outputs a message to syslog or stderr, depending on the implementation.
The format must guarantee that the final message does not exceed 1024
characters. The message should not contain newline. */
void error(const char *fmt, ...);
/* Outputs a message to syslog or stderr, depending on the implementation.
The format must guarantee that the final message does not exceed 1024
characters. The message should not contain newline.
This call never returns. */
void fatal(const char *fmt, ...);
/* Registers a cleanup function to be called by fatal() 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 frunction 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(int port, const char *host,
int 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(int port, const char *host,
int 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);
/* Local Xauthority file (server only). */
extern char *xauthfile;
/* 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;
};
#ifdef KRB4
#include <krb.h>
/* 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 ssh_tf_init(uid_t uid);
#ifdef AFS
#include <kafs.h>
/* Accept passed Kerberos v4 ticket-granting ticket and AFS tokens. */
int auth_kerberos_tgt(struct passwd *pw, const char *string);
int auth_afs_token(char *server_user, uid_t uid, const char *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 <skey.h>
char *skey_fake_keyinfo(char *username);
#endif /* SKEY */
#endif /* SSH_H */
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