* Patch from Frédéric Moulins adding options to authorized_keys.

Needs review.

--HG--
branch : pubkey-options
extra : convert_revision : 26872f944d79ddacff1070aab32115a6d726392c

Makefile.in

@@ -23,7 +23,7 @@ COMMONOBJS=dbutil.o buffer.o \
 		atomicio.o compat.o  fake-rfc2553.o
 
 SVROBJS=svr-kex.o svr-algo.o svr-auth.o sshpty.o \
-		svr-authpasswd.o svr-authpubkey.o svr-session.o svr-service.o \
+		svr-authpasswd.o svr-authpubkey.o svr-authpubkeyoptions.o svr-session.o svr-service.o \
 		svr-chansession.o svr-runopts.o svr-agentfwd.o svr-main.o svr-x11fwd.o\
 		svr-tcpfwd.o svr-authpam.o
 

auth.h

@@ -26,6 +26,7 @@
 #define _AUTH_H_
 
 #include "includes.h"
+#include "chansession.h"
 
 void svr_authinitialise();
 void cli_authinitialise();
@@ -38,6 +39,25 @@ void svr_auth_password();
 void svr_auth_pubkey();
 void svr_auth_pam();
 
+#ifdef ENABLE_SVR_PUBKEY_OPTIONS
+int svr_pubkey_allows_agentfwd();
+int svr_pubkey_allows_tcpfwd();
+int svr_pubkey_allows_x11fwd();
+int svr_pubkey_allows_pty();
+void svr_pubkey_set_forced_command(struct ChanSess *chansess);
+void svr_pubkey_options_cleanup();
+int svr_add_pubkey_options(const char* opts);
+#else
+/* no option : success */
+#define svr_pubkey_allows_agentfwd() 1
+#define svr_pubkey_allows_tcpfwd() 1
+#define svr_pubkey_allows_x11fwd() 1
+#define svr_pubkey_allows_pty() 1
+static inline void svr_pubkey_set_forced_command(struct ChanSess *chansess) { }
+static inline void svr_pubkey_options_cleanup() { }
+#define svr_add_pubkey_options(x) DROPBEAR_SUCCESS
+#endif
+
 /* Client functions */
 void recv_msg_userauth_failure();
 void recv_msg_userauth_success();
@@ -97,6 +117,10 @@ struct AuthState {
 	char *pw_shell;
 	char *pw_name;
 	char *pw_passwd;
+#ifdef ENABLE_SVR_PUBKEY_OPTIONS
+	struct PubKeyOptions* pubkey_options;
+#endif
+
 };
 
 struct SignKeyList;
@@ -111,4 +135,18 @@ struct SignKeyList {
 
 };
 
+#ifdef ENABLE_SVR_PUBKEY_OPTIONS
+struct PubKeyOptions;
+struct PubKeyOptions {
+	/* Flags */
+	int no_port_forwarding_flag;
+	int no_agent_forwarding_flag;
+	int no_x11_forwarding_flag;
+	int no_pty_flag;
+	/* "command=" option. */
+	unsigned char * forced_command;
+
+};
+#endif
+
 #endif /* _AUTH_H_ */

options.h

@@ -136,6 +136,11 @@ etc) slower (perhaps by 50%). Recommended for most small systems. */
 /*#define ENABLE_SVR_PAM_AUTH */ /* requires ./configure --enable-pam */
 #define ENABLE_SVR_PUBKEY_AUTH
 
+/* Wether to ake public key options in authorized_keys file into account */
+#ifdef ENABLE_SVR_PUBKEY_AUTH
+#define ENABLE_SVR_PUBKEY_OPTIONS
+#endif
+
 #define ENABLE_CLI_PASSWORD_AUTH
 #define ENABLE_CLI_PUBKEY_AUTH
 #define ENABLE_CLI_INTERACT_AUTH

svr-agentfwd.c

@@ -39,6 +39,7 @@
 #include "buffer.h"
 #include "random.h"
 #include "listener.h"
+#include "auth.h"
 
 #define AGENTDIRPREFIX "/tmp/dropbear-"
 
@@ -52,6 +53,10 @@ int agentreq(struct ChanSess * chansess) {
 
 	int fd;
 
+	if (!svr_pubkey_allows_agentfwd()) {
+		return DROPBEAR_FAILURE;
+	}
+
 	if (chansess->agentlistener != NULL) {
 		return DROPBEAR_FAILURE;
 	}

svr-authpubkey.c

@@ -21,6 +21,37 @@
  * 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:
+ *
+ * 	Copyright (c) 2000 Markus Friedl.  All rights reserved.
+ * 	
+ * 	Redistribution and use in source and binary forms, with or without
+ * 	modification, are permitted provided that the following conditions
+ * 	are met:
+ * 	1. Redistributions of source code must retain the above copyright
+ * 	   notice, this list of conditions and the following disclaimer.
+ * 	2. Redistributions in binary form must reproduce the above copyright
+ * 	   notice, this list of conditions and the following disclaimer in the
+ * 	   documentation and/or other materials provided with the distribution.
+ * 	
+ * 	THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * 	IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * 	OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * 	IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * 	INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * 	NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * 	DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * 	THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * 	(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * 	THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This copyright and permission notice applies to the code parsing public keys
+ * options string which can also be found in OpenSSH auth2-pubkey.c file 
+ * (user_key_allowed2). It has been adapted to work with buffers.
+ *
+ */
 
 /* Process a pubkey auth request */
 
@@ -158,7 +189,8 @@ static int checkpubkey(unsigned char* algo, unsigned int algolen,
 	char * filename = NULL;
 	int ret = DROPBEAR_FAILURE;
 	buffer * line = NULL;
-	unsigned int len, pos;
+	unsigned int len, pos, quoted;
+	const char *options = NULL;
 
 	TRACE(("enter checkpubkey"))
 
@@ -196,6 +228,8 @@ static int checkpubkey(unsigned char* algo, unsigned int algolen,
 
 	/* iterate through the lines */
 	do {
+		/* new line : potentially new options */
+		options = NULL;
 
 		if (buf_getline(line, authfile) == DROPBEAR_FAILURE) {
 			/* EOF reached */
@@ -208,11 +242,40 @@ static int checkpubkey(unsigned char* algo, unsigned int algolen,
 			continue; /* line is too short for it to be a valid key */
 		}
 
-		/* check the key type - this also stops us from using keys
+		/* check the key type - will fail if there are options */
-		 * which have options with them */
+		if (strncmp(buf_getptr(line, algolen), algo, algolen) != 0) {
+			/* there may be options or a commented line */
+			if ('#' == line->data[line->pos]) continue;
+			/* no comment, skip to next space character */
+			len = 0;
+			pos = line->pos;
+			options = buf_getptr(line, 1);
+			quoted = 0;
+			while (line->data[pos] 
+				&& (quoted || (line->data[pos] != ' '
+						&& line->data[pos] != '\t'
+						&& line->data[pos] != '\n'
+						&& line->data[pos] != '\r'))) { 
+				pos++;
+				if (line->data[pos] == '\\' 
+					&& line->data[pos+1] == '"') { 
+					pos++;	/* skip both */ 
+				} else if (line->data[pos] == '"') 
+					quoted = !quoted; 
+			} /* line->data[pos] == ['\0'|' '|'\t'] */
+
+			/* skip line if there is nothing left */
+			if (pos >= line->len) continue;
+			/* skip line if it begins with a space or tab character */
+			if (pos == line->pos) continue;
+			/* set the position of the line after what we have read */
+			buf_setpos(line, pos+1);
+			/* give a second chance to the algo */
+			if (line->pos + algolen > line->len) continue;
 			if (strncmp(buf_getptr(line, algolen), algo, algolen) != 0) { 
 				continue;
 			 }
+		}
 		buf_incrpos(line, algolen);
 		
 		/* check for space (' ') character */
@@ -232,6 +295,11 @@ static int checkpubkey(unsigned char* algo, unsigned int algolen,
 		TRACE(("checkpubkey: line pos = %d len = %d", line->pos, line->len))
 
 		ret = cmp_base64_key(keyblob, keybloblen, algo, algolen, line, NULL);
+
+		if (ret == DROPBEAR_SUCCESS) {
+			ret = svr_add_pubkey_options(options);
+		}
+
 		if (ret == DROPBEAR_SUCCESS) {
 			break;
 		}
@@ -343,5 +411,4 @@ static int checkfileperm(char * filename) {
 	return DROPBEAR_SUCCESS;
 }
 
-
 #endif

svr-authpubkeyoptions.c

@@ -0,0 +1,223 @@
+/*
+ * 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 'command' public key option */
+void svr_pubkey_set_forced_command(struct ChanSess *chansess) {
+	if (ses.authstate.pubkey_options)
+		chansess->cmd = ses.authstate.pubkey_options->forced_command;
+}
+
+/* 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;
+	}
+}
+
+/* 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(const char* opts) {
+	const char *cp;
+	int i;
+	int ret = DROPBEAR_FAILURE;
+
+	TRACE(("enter addpubkeyoptions"))
+
+	if (!opts || *opts == ' ') {
+		/* no option, success */
+		ret = DROPBEAR_SUCCESS;
+		goto end;
+	}
+	
+	ses.authstate.pubkey_options = (struct PubKeyOptions*)m_malloc(sizeof( struct PubKeyOptions ));
+
+	while (*opts && *opts != ' ' && *opts != '\t') {
+		cp = "no-port-forwarding";
+		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
+			dropbear_log(LOG_WARNING, "Port forwarding disabled.");
+			ses.authstate.pubkey_options->no_port_forwarding_flag = 1;
+			opts += strlen(cp);
+			goto next_option;
+		}
+#ifdef ENABLE_AGENTFWD
+		cp = "no-agent-forwarding";
+		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
+			dropbear_log(LOG_WARNING, "Agent forwarding disabled.");
+			ses.authstate.pubkey_options->no_agent_forwarding_flag = 1;
+			opts += strlen(cp);
+			goto next_option;
+		}
+#endif
+#ifdef ENABLE_X11FWD
+		cp = "no-X11-forwarding";
+		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
+			dropbear_log(LOG_WARNING, "X11 forwarding disabled.");
+			ses.authstate.pubkey_options->no_x11_forwarding_flag = 1;
+			opts += strlen(cp);
+			goto next_option;
+		}
+#endif
+		cp = "no-pty";
+		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
+			dropbear_log(LOG_WARNING, "Pty allocation disabled.");
+			ses.authstate.pubkey_options->no_pty_flag = 1;
+			opts += strlen(cp);
+			goto next_option;
+		}
+		cp = "command=\"";
+		if (strncasecmp(opts, cp, strlen(cp)) == 0) {
+			opts += strlen(cp);
+			ses.authstate.pubkey_options->forced_command = (char*)m_malloc(strlen(opts) + 1);
+			i = 0;
+			while (*opts) {
+				if (*opts == '"')
+					break;
+				if (*opts == '\\' && opts[1] == '"') {
+					opts += 2;
+					ses.authstate.pubkey_options->forced_command[i++] = '"';
+					continue;
+				}
+				ses.authstate.pubkey_options->forced_command[i++] = *opts++;
+			}
+			if (!*opts) {
+				dropbear_log(LOG_WARNING, 
+						"Missing end quote in public key command option");
+				m_free(ses.authstate.pubkey_options->forced_command);
+				ses.authstate.pubkey_options->forced_command = NULL;
+				goto bad_option;
+			}
+			ses.authstate.pubkey_options->forced_command[i] = '\0';
+			if (strlen(ses.authstate.pubkey_options->forced_command) > MAX_CMD_LEN) {
+				dropbear_log(LOG_WARNING, 
+						"Public key option command too long (>MAX_CMD_LEN).");
+				m_free(ses.authstate.pubkey_options->forced_command);
+				ses.authstate.pubkey_options->forced_command = NULL;
+				goto bad_option;
+			}
+			dropbear_log(LOG_WARNING, "Forced command '%s'", 
+				ses.authstate.pubkey_options->forced_command);
+			opts++;
+			goto next_option;
+		}
+		next_option:
+		/*
+		 * Skip the comma, and move to the next option
+		 * (or break out if there are no more).
+		 */
+		if (!*opts) {
+			TRACE(("Bugs in svr-chansession.c pubkey option processing."))
+		}
+		if (*opts == ' ' || *opts == '\t') {
+			break;		/* End of options. */
+		}
+		if (*opts != ',') {
+			goto bad_option;
+		}
+		opts++;
+		/* 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 : '%.50s'", opts);
+
+end:
+	TRACE(("leave addpubkeyoptions"))
+	return ret;
+
+}
+
+#endif

svr-chansession.c

@@ -37,6 +37,7 @@
 #include "x11fwd.h"
 #include "agentfwd.h"
 #include "runopts.h"
+#include "auth.h"
 
 /* Handles sessions (either shells or programs) requested by the client */
 
@@ -527,6 +528,12 @@ static int sessionpty(struct ChanSess * chansess) {
 	struct passwd * pw = NULL;
 
 	TRACE(("enter sessionpty"))
+
+	if (!svr_pubkey_allows_pty()) {
+		TRACE(("leave sessionpty : pty forbidden by public key option"))
+		return DROPBEAR_FAILURE;
+	}
+
 	chansess->term = buf_getstring(ses.payload, &termlen);
 	if (termlen > MAX_TERM_LEN) {
 		/* TODO send disconnect ? */
@@ -582,8 +589,12 @@ static int sessioncommand(struct Channel *channel, struct ChanSess *chansess,
 		return DROPBEAR_FAILURE;
 	}
 
+	/* take public key option 'command' into account */
+	svr_pubkey_set_forced_command(chansess);
+
 	if (iscmd) {
 		/* "exec" */
+		if (chansess->cmd == NULL) {
 			chansess->cmd = buf_getstring(ses.payload, &cmdlen);
 
 			if (cmdlen > MAX_CMD_LEN) {
@@ -591,6 +602,7 @@ static int sessioncommand(struct Channel *channel, struct ChanSess *chansess,
 				/* TODO - send error - too long ? */
 				return DROPBEAR_FAILURE;
 			}
+		}
 		if (issubsys) {
 #ifdef SFTPSERVER_PATH
 			if ((cmdlen == 4) && strncmp(chansess->cmd, "sftp", 4) == 0) {

svr-session.c

@@ -144,6 +144,9 @@ void svr_dropbear_exit(int exitcode, const char* format, va_list param) {
 
 	_dropbear_log(LOG_INFO, fmtbuf, param);
 
+	/* free potential public key options */
+	svr_pubkey_options_cleanup();
+
 	/* must be after we've done with username etc */
 	common_session_cleanup();
 

svr-tcpfwd.c

@@ -32,6 +32,7 @@
 #include "packet.h"
 #include "listener.h"
 #include "runopts.h"
+#include "auth.h"
 
 #ifdef ENABLE_SVR_REMOTETCPFWD
 
@@ -72,7 +73,7 @@ void recv_msg_global_request_remotetcp() {
 
 	TRACE(("enter recv_msg_global_request_remotetcp"))
 
-	if (svr_opts.noremotetcp) {
+	if (svr_opts.noremotetcp || !svr_pubkey_allows_tcpfwd()) {
 		TRACE(("leave recv_msg_global_request_remotetcp: remote tcp forwarding disabled"))
 		goto out;
 	}
@@ -236,7 +237,7 @@ static int newtcpdirect(struct Channel * channel) {
 	int len;
 	int err = SSH_OPEN_ADMINISTRATIVELY_PROHIBITED;
 
-	if (svr_opts.nolocaltcp) {
+	if (svr_opts.nolocaltcp || !svr_pubkey_allows_tcpfwd()) {
 		TRACE(("leave newtcpdirect: local tcp forwarding disabled"))
 		goto out;
 	}

svr-x11fwd.c

@@ -33,6 +33,7 @@
 #include "channel.h"
 #include "packet.h"
 #include "buffer.h"
+#include "auth.h"
 
 #define X11BASEPORT 6000
 #define X11BINDBASE 6010
@@ -47,6 +48,10 @@ int x11req(struct ChanSess * chansess) {
 
 	int fd;
 
+	if (!svr_pubkey_allows_x11fwd()) {
+		return DROPBEAR_FAILURE;
+	}
+
 	/* we already have an x11 connection */
 	if (chansess->x11listener != NULL) {
 		return DROPBEAR_FAILURE;

tcpfwd.h

@@ -55,6 +55,7 @@ struct TCPFwdList {
 
 /* Server */
 void recv_msg_global_request_remotetcp();
+
 extern const struct ChanType svr_chan_tcpdirect;
 
 /* Client */