224 lines
6.3 KiB
C
224 lines
6.3 KiB
C
/*
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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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* RSA-based authentication. This code determines whether to admit a login
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* based on RSA authentication. This file also contains functions to check
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* validity of the host key.
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*
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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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#include "includes.h"
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RCSID("$OpenBSD: auth-options.c,v 1.4 2000/09/07 21:13:36 markus Exp $");
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#include "ssh.h"
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#include "packet.h"
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#include "xmalloc.h"
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#include "match.h"
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/* Flags set authorized_keys flags */
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int no_port_forwarding_flag = 0;
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int no_agent_forwarding_flag = 0;
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int no_x11_forwarding_flag = 0;
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int no_pty_flag = 0;
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/* "command=" option. */
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char *forced_command = NULL;
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/* "environment=" options. */
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struct envstring *custom_environment = NULL;
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/* return 1 if access is granted, 0 if not. side effect: sets key option flags */
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int
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auth_parse_options(struct passwd *pw, char *options, unsigned long linenum)
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{
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const char *cp;
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if (!options)
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return 1;
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while (*options && *options != ' ' && *options != '\t') {
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cp = "no-port-forwarding";
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if (strncmp(options, cp, strlen(cp)) == 0) {
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packet_send_debug("Port forwarding disabled.");
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no_port_forwarding_flag = 1;
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options += strlen(cp);
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goto next_option;
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}
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cp = "no-agent-forwarding";
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if (strncmp(options, cp, strlen(cp)) == 0) {
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packet_send_debug("Agent forwarding disabled.");
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no_agent_forwarding_flag = 1;
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options += strlen(cp);
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goto next_option;
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}
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cp = "no-X11-forwarding";
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if (strncmp(options, cp, strlen(cp)) == 0) {
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packet_send_debug("X11 forwarding disabled.");
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no_x11_forwarding_flag = 1;
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options += strlen(cp);
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goto next_option;
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}
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cp = "no-pty";
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if (strncmp(options, cp, strlen(cp)) == 0) {
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packet_send_debug("Pty allocation disabled.");
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no_pty_flag = 1;
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options += strlen(cp);
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goto next_option;
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}
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cp = "command=\"";
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if (strncmp(options, cp, strlen(cp)) == 0) {
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int i;
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options += strlen(cp);
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forced_command = xmalloc(strlen(options) + 1);
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i = 0;
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while (*options) {
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if (*options == '"')
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break;
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if (*options == '\\' && options[1] == '"') {
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options += 2;
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forced_command[i++] = '"';
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continue;
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}
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forced_command[i++] = *options++;
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}
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if (!*options) {
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debug("%.100s, line %lu: missing end quote",
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SSH_USER_PERMITTED_KEYS, linenum);
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packet_send_debug("%.100s, line %lu: missing end quote",
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SSH_USER_PERMITTED_KEYS, linenum);
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continue;
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}
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forced_command[i] = 0;
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packet_send_debug("Forced command: %.900s", forced_command);
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options++;
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goto next_option;
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}
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cp = "environment=\"";
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if (strncmp(options, cp, strlen(cp)) == 0) {
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int i;
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char *s;
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struct envstring *new_envstring;
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options += strlen(cp);
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s = xmalloc(strlen(options) + 1);
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i = 0;
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while (*options) {
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if (*options == '"')
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break;
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if (*options == '\\' && options[1] == '"') {
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options += 2;
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s[i++] = '"';
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continue;
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}
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s[i++] = *options++;
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}
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if (!*options) {
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debug("%.100s, line %lu: missing end quote",
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SSH_USER_PERMITTED_KEYS, linenum);
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packet_send_debug("%.100s, line %lu: missing end quote",
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SSH_USER_PERMITTED_KEYS, linenum);
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continue;
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}
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s[i] = 0;
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packet_send_debug("Adding to environment: %.900s", s);
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debug("Adding to environment: %.900s", s);
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options++;
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new_envstring = xmalloc(sizeof(struct envstring));
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new_envstring->s = s;
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new_envstring->next = custom_environment;
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custom_environment = new_envstring;
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goto next_option;
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}
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cp = "from=\"";
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if (strncmp(options, cp, strlen(cp)) == 0) {
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int mname, mip;
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char *patterns = xmalloc(strlen(options) + 1);
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int i;
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options += strlen(cp);
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i = 0;
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while (*options) {
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if (*options == '"')
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break;
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if (*options == '\\' && options[1] == '"') {
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options += 2;
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patterns[i++] = '"';
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continue;
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}
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patterns[i++] = *options++;
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}
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if (!*options) {
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debug("%.100s, line %lu: missing end quote",
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SSH_USER_PERMITTED_KEYS, linenum);
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packet_send_debug("%.100s, line %lu: missing end quote",
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SSH_USER_PERMITTED_KEYS, linenum);
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continue;
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}
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patterns[i] = 0;
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options++;
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/*
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* Deny access if we get a negative
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* match for the hostname or the ip
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* or if we get not match at all
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*/
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mname = match_hostname(get_canonical_hostname(),
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patterns, strlen(patterns));
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mip = match_hostname(get_remote_ipaddr(),
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patterns, strlen(patterns));
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xfree(patterns);
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if (mname == -1 || mip == -1 ||
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(mname != 1 && mip != 1)) {
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log("Authentication tried for %.100s with correct key but not from a permitted host (host=%.200s, ip=%.200s).",
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pw->pw_name, get_canonical_hostname(),
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get_remote_ipaddr());
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packet_send_debug("Your host '%.200s' is not permitted to use this key for login.",
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get_canonical_hostname());
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/* key invalid for this host, reset flags */
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no_agent_forwarding_flag = 0;
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no_port_forwarding_flag = 0;
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no_pty_flag = 0;
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no_x11_forwarding_flag = 0;
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while (custom_environment) {
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struct envstring *ce = custom_environment;
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custom_environment = ce->next;
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xfree(ce->s);
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xfree(ce);
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}
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if (forced_command) {
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xfree(forced_command);
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forced_command = NULL;
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}
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/* deny access */
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return 0;
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}
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/* Host name matches. */
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goto next_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)
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fatal("Bugs in auth-options.c option processing.");
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if (*options == ' ' || *options == '\t')
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break; /* End of options. */
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if (*options != ',')
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goto bad_option;
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options++;
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/* Process the next option. */
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}
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/* grant access */
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return 1;
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bad_option:
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log("Bad options in %.100s file, line %lu: %.50s",
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SSH_USER_PERMITTED_KEYS, linenum, options);
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packet_send_debug("Bad options in %.100s file, line %lu: %.50s",
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SSH_USER_PERMITTED_KEYS, linenum, options);
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/* deny access */
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return 0;
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}
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