session.h 8.63 KB
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/*
 * Dropbear - a SSH2 server
 * 
 * Copyright (c) 2002,2003 Matt Johnston
 * All rights reserved.
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE. */

#ifndef _SESSION_H_
#define _SESSION_H_

#include "includes.h"
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#include "options.h"
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#include "buffer.h"
#include "signkey.h"
#include "kex.h"
#include "auth.h"
#include "channel.h"
#include "queue.h"
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#include "listener.h"
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#include "packet.h"
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#include "tcpfwd.h"
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#include "chansession.h"
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extern int sessinitdone; /* Is set to 0 somewhere */
extern int exitflag;

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void common_session_init(int sock_in, int sock_out);
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void session_loop(void(*loophandler)());
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void common_session_cleanup();
void session_identification();
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void send_msg_ignore();
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const char* get_user_shell();
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void fill_passwd(const char* username);
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/* Server */
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void svr_session(int sock, int childpipe);
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void svr_dropbear_exit(int exitcode, const char* format, va_list param);
void svr_dropbear_log(int priority, const char* format, va_list param);

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/* Client */
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void cli_session(int sock_in, int sock_out);
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void cli_session_cleanup();
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void cleantext(unsigned char* dirtytext);
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/* crypto parameters that are stored individually for transmit and receive */
struct key_context_directional {
	const struct dropbear_cipher *algo_crypt; /* NULL for none */
	const struct dropbear_cipher_mode *crypt_mode;
	const struct dropbear_hash *algo_mac; /* NULL for none */
	int hash_index; /* lookup for libtomcrypt */
	char algo_comp; /* compression */
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#ifndef DISABLE_ZLIB
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	z_streamp zstream;
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#endif
	/* actual keys */
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	union {
		symmetric_CBC cbc;
#ifdef DROPBEAR_ENABLE_CTR_MODE
		symmetric_CTR ctr;
#endif
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	} cipher_state;
	unsigned char mackey[MAX_MAC_KEY];
};

struct key_context {

	struct key_context_directional recv;
	struct key_context_directional trans;
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	char algo_kex;
	char algo_hostkey;

	int allow_compress; /* whether compression has started (useful in 
							[email protected] delayed compression case) */
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};

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struct packetlist;
struct packetlist {
	struct packetlist *next;
	buffer * payload;
};

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struct sshsession {

	/* Is it a client or server? */
	unsigned char isserver;

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	time_t connect_time; /* time the connection was established
							(cleared after auth once we're not
							respecting AUTH_TIMEOUT any more) */
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	int sock_in;
	int sock_out;
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	unsigned char *remoteident;

	int maxfd; /* the maximum file descriptor to check with select() */


	/* Packet buffers/values etc */
	buffer *writepayload; /* Unencrypted payload to write - this is used
							 throughout the code, as handlers fill out this
							 buffer with the packet to send. */
	struct Queue writequeue; /* A queue of encrypted packets to send */
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	buffer *readbuf; /* From the wire, decrypted in-place */
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	buffer *payload; /* Post-decompression, the actual SSH packet */
	unsigned int transseq, recvseq; /* Sequence IDs */

	/* Packet-handling flags */
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	const packettype * packettypes; /* Packet handler mappings for this
										session, see process-packet.c */

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	unsigned dataallowed : 1; /* whether we can send data packets or we are in
								 the middle of a KEX or something */

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	unsigned char requirenext; /* byte indicating what packet we require next, 
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								or 0x00 for any */

	unsigned char ignorenext; /* whether to ignore the next packet,
								 used for kex_follows stuff */
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	unsigned char lastpacket; /* What the last received packet type was */
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	int signal_pipe[2]; /* stores endpoints of a self-pipe used for
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						   race-free signal handling */
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	time_t last_trx_packet_time; /* time of the last packet transmission, for
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							keepalive purposes */
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	time_t last_packet_time; /* time of the last packet transmission or receive, for
								idle timeout purposes */


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	/* KEX/encryption related */
	struct KEXState kexstate;
	struct key_context *keys;
	struct key_context *newkeys;
	unsigned char *session_id; /* this is the hash from the first kex */
	/* The below are used temorarily during kex, are freed after use */
	mp_int * dh_K; /* SSH_MSG_KEXDH_REPLY and sending SSH_MSH_NEWKEYS */
	unsigned char hash[SHA1_HASH_SIZE]; /* the hash*/
	buffer* kexhashbuf; /* session hash buffer calculated from various packets*/
	buffer* transkexinit; /* the kexinit packet we send should be kept so we
							 can add it to the hash when generating keys */
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	/* a list of queued replies that should be sent after a KEX has
	   concluded (ie, while dataallowed was unset)*/
	struct packetlist *reply_queue_head, *reply_queue_tail;
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	algo_type*(*buf_match_algo)(buffer*buf, algo_type localalgos[],
			int *goodguess); /* The function to use to choose which algorithm
								to use from the ones presented by the remote
								side. Is specific to the client/server mode,
								hence the function-pointer callback.*/
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	void(*remoteclosed)(); /* A callback to handle closure of the
									  remote connection */


	struct AuthState authstate; /* Common amongst client and server, since most
								   struct elements are common */
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	/* Channel related */
	struct Channel ** channels; /* these pointers may be null */
	unsigned int chansize; /* the number of Channel*s allocated for channels */
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	unsigned int chancount; /* the number of Channel*s in use */
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	const struct ChanType **chantypes; /* The valid channel types */
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	/* TCP forwarding - where manage listeners */
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	struct Listener ** listeners;
	unsigned int listensize;
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	/* Whether to allow binding to privileged ports (<1024). This doesn't
	 * really belong here, but nowhere else fits nicely */
	int allowprivport;
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};

struct serversession {

	/* Server specific options */
	int childpipe; /* kept open until we successfully authenticate */
	/* userauth */

	struct ChildPid * childpids; /* array of mappings childpid<->channel */
	unsigned int childpidsize;

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	/* Used to avoid a race in the exit returncode handling - see
	 * svr-chansession.c for details */
	struct exitinfo lastexit;

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	/* The numeric address they connected from, used for logging */
	char * addrstring;

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	/* The resolved remote address, used for lastlog etc */
	char *remotehost;

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#ifdef __uClinux__
	pid_t server_pid;
#endif

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};

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typedef enum {
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	KEX_NOTHING,
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	KEXINIT_RCVD,
	KEXDH_INIT_SENT,
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	KEXDONE
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} cli_kex_state;

typedef enum {
	STATE_NOTHING,
	SERVICE_AUTH_REQ_SENT,
	SERVICE_AUTH_ACCEPT_RCVD,
	SERVICE_CONN_REQ_SENT,
	SERVICE_CONN_ACCEPT_RCVD,
	USERAUTH_REQ_SENT,
	USERAUTH_FAIL_RCVD,
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	USERAUTH_SUCCESS_RCVD,
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	SESSION_RUNNING
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} cli_state;
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struct clientsession {

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	mp_int *dh_e, *dh_x; /* Used during KEX */
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	cli_kex_state kex_state; /* Used for progressing KEX */
	cli_state state; /* Used to progress auth/channelsession etc */
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	unsigned donefirstkex : 1; /* Set when we set sentnewkeys, never reset */
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	int tty_raw_mode; /* Whether we're in raw mode (and have to clean up) */
	struct termios saved_tio;
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	int stdincopy;
	int stdinflags;
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	int stdoutcopy;
	int stdoutflags;
	int stderrcopy;
	int stderrflags;
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	int winchange; /* Set to 1 when a windowchange signal happens */

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	int lastauthtype; /* either AUTH_TYPE_PUBKEY or AUTH_TYPE_PASSWORD,
						 for the last type of auth we tried */
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#ifdef ENABLE_CLI_INTERACT_AUTH
	int auth_interact_failed; /* flag whether interactive auth can still
								 be used */
	int interact_request_received; /* flag whether we've received an 
									  info request from the server for
									  interactive auth.*/
#endif
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	sign_key *lastprivkey;
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	int retval; /* What the command exit status was - we emulate it */
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#if 0
	TODO
	struct AgentkeyList *agentkeys; /* Keys to use for public-key auth */
#endif

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};

/* Global structs storing the state */
extern struct sshsession ses;

#ifdef DROPBEAR_SERVER
extern struct serversession svr_ses;
#endif /* DROPBEAR_SERVER */

#ifdef DROPBEAR_CLIENT
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extern struct clientsession cli_ses;
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#endif /* DROPBEAR_CLIENT */

#endif /* _SESSION_H_ */