svr-authpubkeyoptions.c - third_party/dropbear - Git at Google

 /*
  * Dropbear - a SSH2 server
  *
  * Copyright (c) 2008 Frederic Moulins
  * 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.
  *
  * This file incorporates work covered by the following copyright and
  * permission notice:
  *
  * 	Author: Tatu Ylonen <ylo@cs.hut.fi>
  * 	Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
  * 	              All rights reserved
  * 	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".
  *
  * This copyright and permission notice applies to the code parsing public keys
  * options string which can also be found in OpenSSH auth-options.c file
  * (auth_parse_options).
  *
  */

 /* Process pubkey options during a pubkey auth request */
 #include "includes.h"
 #include "session.h"
 #include "dbutil.h"
 #include "signkey.h"
 #include "auth.h"

 #ifdef ENABLE_SVR_PUBKEY_OPTIONS

 /* Returns 1 if pubkey allows agent forwarding,
  * 0 otherwise */
 int svr_pubkey_allows_agentfwd() {
 	if (ses.authstate.pubkey_options
 		&& ses.authstate.pubkey_options->no_agent_forwarding_flag) {
 		return 0;
 	}
 	return 1;
 }

 /* Returns 1 if pubkey allows tcp forwarding,
  * 0 otherwise */
 int svr_pubkey_allows_tcpfwd() {
 	if (ses.authstate.pubkey_options
 		&& ses.authstate.pubkey_options->no_port_forwarding_flag) {
 		return 0;
 	}
 	return 1;
 }

 /* Returns 1 if pubkey allows x11 forwarding,
  * 0 otherwise */
 int svr_pubkey_allows_x11fwd() {
 	if (ses.authstate.pubkey_options
 		&& ses.authstate.pubkey_options->no_x11_forwarding_flag) {
 		return 0;
 	}
 	return 1;
 }

 /* Returns 1 if pubkey allows pty, 0 otherwise */
 int svr_pubkey_allows_pty() {
 	if (ses.authstate.pubkey_options
 		&& ses.authstate.pubkey_options->no_pty_flag) {
 		return 0;
 	}
 	return 1;
 }

 /* Set chansession command to the one forced
  * by any 'command' public key option. */
 void svr_pubkey_set_forced_command(struct ChanSess *chansess) {
 	if (ses.authstate.pubkey_options) {
 		if (chansess->cmd) {
 			/* original_command takes ownership */
 			chansess->original_command = chansess->cmd;
 		} else {
 			chansess->original_command = m_strdup("");
 		}
 		chansess->cmd = m_strdup(ses.authstate.pubkey_options->forced_command);
 #ifdef LOG_COMMANDS
 		dropbear_log(LOG_INFO, "Command forced to '%s'", chansess->original_command);
 #endif
 	}
 }

 /* Free potential public key options */
 void svr_pubkey_options_cleanup() {
 	if (ses.authstate.pubkey_options) {
 		m_free(ses.authstate.pubkey_options);
 		ses.authstate.pubkey_options = NULL;
 	}
 }

 /* helper for svr_add_pubkey_options. returns DROPBEAR_SUCCESS if the option is matched,
    and increments the options_buf */
 static int match_option(buffer *options_buf, const char *opt_name) {
 	const unsigned int len = strlen(opt_name);
 	if (options_buf->len - options_buf->pos < len) {
 		return DROPBEAR_FAILURE;
 	}
 	if (strncasecmp(buf_getptr(options_buf, len), opt_name, len) == 0) {
 		buf_incrpos(options_buf, len);
 		return DROPBEAR_SUCCESS;
 	}
 	return DROPBEAR_FAILURE;
 }

 /* Parse pubkey options and set ses.authstate.pubkey_options accordingly.
  * Returns DROPBEAR_SUCCESS if key is ok for auth, DROPBEAR_FAILURE otherwise */
 int svr_add_pubkey_options(buffer *options_buf, int line_num, const char* filename) {
 	int ret = DROPBEAR_FAILURE;

 	TRACE(("enter addpubkeyoptions"))

 	ses.authstate.pubkey_options = (struct PubKeyOptions*)m_malloc(sizeof( struct PubKeyOptions ));

 	buf_setpos(options_buf, 0);
 	while (options_buf->pos < options_buf->len) {
 		if (match_option(options_buf, "no-port-forwarding") == DROPBEAR_SUCCESS) {
 			dropbear_log(LOG_WARNING, "Port forwarding disabled.");
 			ses.authstate.pubkey_options->no_port_forwarding_flag = 1;
 			goto next_option;
 		}
 #ifdef ENABLE_SVR_AGENTFWD
 		if (match_option(options_buf, "no-agent-forwarding") == DROPBEAR_SUCCESS) {
 			dropbear_log(LOG_WARNING, "Agent forwarding disabled.");
 			ses.authstate.pubkey_options->no_agent_forwarding_flag = 1;
 			goto next_option;
 		}
 #endif
 #ifdef ENABLE_X11FWD
 		if (match_option(options_buf, "no-X11-forwarding") == DROPBEAR_SUCCESS) {
 			dropbear_log(LOG_WARNING, "X11 forwarding disabled.");
 			ses.authstate.pubkey_options->no_x11_forwarding_flag = 1;
 			goto next_option;
 		}
 #endif
 		if (match_option(options_buf, "no-pty") == DROPBEAR_SUCCESS) {
 			dropbear_log(LOG_WARNING, "Pty allocation disabled.");
 			ses.authstate.pubkey_options->no_pty_flag = 1;
 			goto next_option;
 		}
 		if (match_option(options_buf, "command=\"") == DROPBEAR_SUCCESS) {
 			int escaped = 0;
 			const unsigned char* command_start = buf_getptr(options_buf, 0);
 			while (options_buf->pos < options_buf->len) {
 				const char c = buf_getbyte(options_buf);
 				if (!escaped && c == '"') {
 					const int command_len = buf_getptr(options_buf, 0) - command_start;
 					ses.authstate.pubkey_options->forced_command = m_malloc(command_len);
 					memcpy(ses.authstate.pubkey_options->forced_command,
 							command_start, command_len-1);
 					ses.authstate.pubkey_options->forced_command[command_len-1] = '\0';
 					dropbear_log(LOG_WARNING, "Forced command '%s'",
 						ses.authstate.pubkey_options->forced_command);
 					goto next_option;
 				}
 				escaped = (!escaped && c == '\\');
 			}
 			dropbear_log(LOG_WARNING, "Badly formatted command= authorized_keys option");
 			goto bad_option;
 		}

 next_option:
 		/*
 		 * Skip the comma, and move to the next option
 		 * (or break out if there are no more).
 		 */
 		if (options_buf->pos < options_buf->len
 				&& buf_getbyte(options_buf) != ',') {
 			goto bad_option;
 		}
 		/* Process the next option. */
 	}
 	/* parsed all options with no problem */
 	ret = DROPBEAR_SUCCESS;
 	goto end;

 bad_option:
 	ret = DROPBEAR_FAILURE;
 	m_free(ses.authstate.pubkey_options);
 	ses.authstate.pubkey_options = NULL;
 	dropbear_log(LOG_WARNING, "Bad public key options at %s:%d", filename, line_num);

 end:
 	TRACE(("leave addpubkeyoptions"))
 	return ret;
 }

 #endif
	/*
	* Dropbear - a SSH2 server
	*
	* Copyright (c) 2008 Frederic Moulins
	* 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.
	*
	* This file incorporates work covered by the following copyright and
	* permission notice:
	*
	* Author: Tatu Ylonen <ylo@cs.hut.fi>
	* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
	* All rights reserved
	* 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".
	*
	* This copyright and permission notice applies to the code parsing public keys
	* options string which can also be found in OpenSSH auth-options.c file
	* (auth_parse_options).
	*
	*/

	/* Process pubkey options during a pubkey auth request */
	#include "includes.h"
	#include "session.h"
	#include "dbutil.h"
	#include "signkey.h"
	#include "auth.h"

	#ifdef ENABLE_SVR_PUBKEY_OPTIONS

	/* Returns 1 if pubkey allows agent forwarding,
	* 0 otherwise */
	int svr_pubkey_allows_agentfwd() {
	if (ses.authstate.pubkey_options
	&& ses.authstate.pubkey_options->no_agent_forwarding_flag) {
	return 0;
	}
	return 1;
	}

	/* Returns 1 if pubkey allows tcp forwarding,
	* 0 otherwise */
	int svr_pubkey_allows_tcpfwd() {
	if (ses.authstate.pubkey_options
	&& ses.authstate.pubkey_options->no_port_forwarding_flag) {
	return 0;
	}
	return 1;
	}

	/* Returns 1 if pubkey allows x11 forwarding,
	* 0 otherwise */
	int svr_pubkey_allows_x11fwd() {
	if (ses.authstate.pubkey_options
	&& ses.authstate.pubkey_options->no_x11_forwarding_flag) {
	return 0;
	}
	return 1;
	}

	/* Returns 1 if pubkey allows pty, 0 otherwise */
	int svr_pubkey_allows_pty() {
	if (ses.authstate.pubkey_options
	&& ses.authstate.pubkey_options->no_pty_flag) {
	return 0;
	}
	return 1;
	}

	/* Set chansession command to the one forced
	* by any 'command' public key option. */
	void svr_pubkey_set_forced_command(struct ChanSess *chansess) {
	if (ses.authstate.pubkey_options) {
	if (chansess->cmd) {
	/* original_command takes ownership */
	chansess->original_command = chansess->cmd;
	} else {
	chansess->original_command = m_strdup("");
	}
	chansess->cmd = m_strdup(ses.authstate.pubkey_options->forced_command);
	#ifdef LOG_COMMANDS
	dropbear_log(LOG_INFO, "Command forced to '%s'", chansess->original_command);
	#endif
	}
	}

	/* Free potential public key options */
	void svr_pubkey_options_cleanup() {
	if (ses.authstate.pubkey_options) {
	m_free(ses.authstate.pubkey_options);
	ses.authstate.pubkey_options = NULL;
	}
	}

	/* helper for svr_add_pubkey_options. returns DROPBEAR_SUCCESS if the option is matched,
	and increments the options_buf */
	static int match_option(buffer options_buf, const char opt_name) {
	const unsigned int len = strlen(opt_name);
	if (options_buf->len - options_buf->pos < len) {
	return DROPBEAR_FAILURE;
	}
	if (strncasecmp(buf_getptr(options_buf, len), opt_name, len) == 0) {
	buf_incrpos(options_buf, len);
	return DROPBEAR_SUCCESS;
	}
	return DROPBEAR_FAILURE;
	}

	/* Parse pubkey options and set ses.authstate.pubkey_options accordingly.
	* Returns DROPBEAR_SUCCESS if key is ok for auth, DROPBEAR_FAILURE otherwise */
	int svr_add_pubkey_options(buffer options_buf, int line_num, const char filename) {
	int ret = DROPBEAR_FAILURE;

	TRACE(("enter addpubkeyoptions"))

	ses.authstate.pubkey_options = (struct PubKeyOptions*)m_malloc(sizeof( struct PubKeyOptions ));

	buf_setpos(options_buf, 0);
	while (options_buf->pos < options_buf->len) {
	if (match_option(options_buf, "no-port-forwarding") == DROPBEAR_SUCCESS) {
	dropbear_log(LOG_WARNING, "Port forwarding disabled.");
	ses.authstate.pubkey_options->no_port_forwarding_flag = 1;
	goto next_option;
	}
	#ifdef ENABLE_SVR_AGENTFWD
	if (match_option(options_buf, "no-agent-forwarding") == DROPBEAR_SUCCESS) {
	dropbear_log(LOG_WARNING, "Agent forwarding disabled.");
	ses.authstate.pubkey_options->no_agent_forwarding_flag = 1;
	goto next_option;
	}
	#endif
	#ifdef ENABLE_X11FWD
	if (match_option(options_buf, "no-X11-forwarding") == DROPBEAR_SUCCESS) {
	dropbear_log(LOG_WARNING, "X11 forwarding disabled.");
	ses.authstate.pubkey_options->no_x11_forwarding_flag = 1;
	goto next_option;
	}
	#endif
	if (match_option(options_buf, "no-pty") == DROPBEAR_SUCCESS) {
	dropbear_log(LOG_WARNING, "Pty allocation disabled.");
	ses.authstate.pubkey_options->no_pty_flag = 1;
	goto next_option;
	}
	if (match_option(options_buf, "command=\"") == DROPBEAR_SUCCESS) {
	int escaped = 0;
	const unsigned char* command_start = buf_getptr(options_buf, 0);
	while (options_buf->pos < options_buf->len) {
	const char c = buf_getbyte(options_buf);
	if (!escaped && c == '"') {
	const int command_len = buf_getptr(options_buf, 0) - command_start;
	ses.authstate.pubkey_options->forced_command = m_malloc(command_len);
	memcpy(ses.authstate.pubkey_options->forced_command,
	command_start, command_len-1);
	ses.authstate.pubkey_options->forced_command[command_len-1] = '\0';
	dropbear_log(LOG_WARNING, "Forced command '%s'",
	ses.authstate.pubkey_options->forced_command);
	goto next_option;
	}
	escaped = (!escaped && c == '\\');
	}
	dropbear_log(LOG_WARNING, "Badly formatted command= authorized_keys option");
	goto bad_option;
	}

	next_option:
	/*
	* Skip the comma, and move to the next option
	* (or break out if there are no more).
	*/
	if (options_buf->pos < options_buf->len
	&& buf_getbyte(options_buf) != ',') {
	goto bad_option;
	}
	/* Process the next option. */
	}
	/* parsed all options with no problem */
	ret = DROPBEAR_SUCCESS;
	goto end;

	bad_option:
	ret = DROPBEAR_FAILURE;
	m_free(ses.authstate.pubkey_options);
	ses.authstate.pubkey_options = NULL;
	dropbear_log(LOG_WARNING, "Bad public key options at %s:%d", filename, line_num);

	end:
	TRACE(("leave addpubkeyoptions"))
	return ret;
	}

	#endif