213 lines
7.0 KiB
C
213 lines
7.0 KiB
C
/*
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* Dropbear - a SSH2 server
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*
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* Copyright (c) 2008 Frederic Moulins
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* All rights reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*
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* This file incorporates work covered by the following copyright and
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* permission notice:
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*
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* Author: Tatu Ylonen <ylo@cs.hut.fi>
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* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
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* All rights reserved
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* As far as I am concerned, the code I have written for this software
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* can be used freely for any purpose. Any derived versions of this
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* software must be clearly marked as such, and if the derived work is
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* incompatible with the protocol description in the RFC file, it must be
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* called by a name other than "ssh" or "Secure Shell".
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*
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* This copyright and permission notice applies to the code parsing public keys
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* options string which can also be found in OpenSSH auth-options.c file
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* (auth_parse_options).
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*
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*/
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/* Process pubkey options during a pubkey auth request */
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#include "includes.h"
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#include "session.h"
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#include "dbutil.h"
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#include "signkey.h"
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#include "auth.h"
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#ifdef ENABLE_SVR_PUBKEY_OPTIONS
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/* Returns 1 if pubkey allows agent forwarding,
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* 0 otherwise */
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int svr_pubkey_allows_agentfwd() {
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if (ses.authstate.pubkey_options
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&& ses.authstate.pubkey_options->no_agent_forwarding_flag) {
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return 0;
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}
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return 1;
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}
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/* Returns 1 if pubkey allows tcp forwarding,
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* 0 otherwise */
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int svr_pubkey_allows_tcpfwd() {
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if (ses.authstate.pubkey_options
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&& ses.authstate.pubkey_options->no_port_forwarding_flag) {
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return 0;
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}
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return 1;
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}
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/* Returns 1 if pubkey allows x11 forwarding,
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* 0 otherwise */
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int svr_pubkey_allows_x11fwd() {
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if (ses.authstate.pubkey_options
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&& ses.authstate.pubkey_options->no_x11_forwarding_flag) {
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return 0;
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}
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return 1;
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}
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/* Returns 1 if pubkey allows pty, 0 otherwise */
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int svr_pubkey_allows_pty() {
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if (ses.authstate.pubkey_options
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&& ses.authstate.pubkey_options->no_pty_flag) {
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return 0;
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}
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return 1;
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}
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/* Set chansession command to the one forced
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* by any 'command' public key option. */
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void svr_pubkey_set_forced_command(struct ChanSess *chansess) {
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if (ses.authstate.pubkey_options) {
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if (chansess->cmd) {
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/* original_command takes ownership */
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chansess->original_command = chansess->cmd;
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} else {
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chansess->original_command = m_strdup("");
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}
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chansess->cmd = m_strdup(ses.authstate.pubkey_options->forced_command);
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#ifdef LOG_COMMANDS
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dropbear_log(LOG_INFO, "Command forced to '%s'", chansess->original_command);
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#endif
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}
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}
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/* Free potential public key options */
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void svr_pubkey_options_cleanup() {
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if (ses.authstate.pubkey_options) {
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m_free(ses.authstate.pubkey_options);
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ses.authstate.pubkey_options = NULL;
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}
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}
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/* helper for svr_add_pubkey_options. returns DROPBEAR_SUCCESS if the option is matched,
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and increments the options_buf */
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static int match_option(buffer *options_buf, const char *opt_name) {
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const unsigned int len = strlen(opt_name);
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if (options_buf->len - options_buf->pos < len) {
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return DROPBEAR_FAILURE;
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}
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if (strncasecmp(buf_getptr(options_buf, len), opt_name, len) == 0) {
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buf_incrpos(options_buf, len);
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return DROPBEAR_SUCCESS;
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}
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return DROPBEAR_FAILURE;
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}
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/* Parse pubkey options and set ses.authstate.pubkey_options accordingly.
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* Returns DROPBEAR_SUCCESS if key is ok for auth, DROPBEAR_FAILURE otherwise */
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int svr_add_pubkey_options(buffer *options_buf, int line_num, const char* filename) {
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int ret = DROPBEAR_FAILURE;
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TRACE(("enter addpubkeyoptions"))
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ses.authstate.pubkey_options = (struct PubKeyOptions*)m_malloc(sizeof( struct PubKeyOptions ));
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buf_setpos(options_buf, 0);
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while (options_buf->pos < options_buf->len) {
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if (match_option(options_buf, "no-port-forwarding") == DROPBEAR_SUCCESS) {
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dropbear_log(LOG_WARNING, "Port forwarding disabled.");
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ses.authstate.pubkey_options->no_port_forwarding_flag = 1;
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goto next_option;
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}
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#ifdef ENABLE_AGENTFWD
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if (match_option(options_buf, "no-agent-forwarding") == DROPBEAR_SUCCESS) {
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dropbear_log(LOG_WARNING, "Agent forwarding disabled.");
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ses.authstate.pubkey_options->no_agent_forwarding_flag = 1;
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goto next_option;
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}
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#endif
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#ifdef ENABLE_X11FWD
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if (match_option(options_buf, "no-X11-forwarding") == DROPBEAR_SUCCESS) {
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dropbear_log(LOG_WARNING, "X11 forwarding disabled.");
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ses.authstate.pubkey_options->no_x11_forwarding_flag = 1;
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goto next_option;
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}
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#endif
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if (match_option(options_buf, "no-pty") == DROPBEAR_SUCCESS) {
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dropbear_log(LOG_WARNING, "Pty allocation disabled.");
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ses.authstate.pubkey_options->no_pty_flag = 1;
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goto next_option;
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}
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if (match_option(options_buf, "command=\"") == DROPBEAR_SUCCESS) {
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int escaped = 0;
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const unsigned char* command_start = buf_getptr(options_buf, 0);
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while (options_buf->pos < options_buf->len) {
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const char c = buf_getbyte(options_buf);
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if (!escaped && c == '"') {
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const int command_len = buf_getptr(options_buf, 0) - command_start;
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ses.authstate.pubkey_options->forced_command = m_malloc(command_len);
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memcpy(ses.authstate.pubkey_options->forced_command,
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command_start, command_len-1);
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ses.authstate.pubkey_options->forced_command[command_len-1] = '\0';
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dropbear_log(LOG_WARNING, "Forced command '%s'",
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ses.authstate.pubkey_options->forced_command);
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goto next_option;
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}
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escaped = (!escaped && c == '\\');
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}
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dropbear_log(LOG_WARNING, "Badly formatted command= authorized_keys option");
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goto bad_option;
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}
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next_option:
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/*
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* Skip the comma, and move to the next option
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* (or break out if there are no more).
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*/
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if (options_buf->pos < options_buf->len
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&& buf_getbyte(options_buf) != ',') {
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goto bad_option;
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}
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/* Process the next option. */
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}
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/* parsed all options with no problem */
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ret = DROPBEAR_SUCCESS;
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goto end;
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bad_option:
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ret = DROPBEAR_FAILURE;
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m_free(ses.authstate.pubkey_options);
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ses.authstate.pubkey_options = NULL;
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dropbear_log(LOG_WARNING, "Bad public key options at %s:%d", filename, line_num);
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end:
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TRACE(("leave addpubkeyoptions"))
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return ret;
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}
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#endif
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