[openssh.git] / auth-options.c

/*
 * Author: Tatu Ylonen <ylo@cs.hut.fi>
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 * RSA-based authentication.  This code determines whether to admit a login
 * based on RSA authentication.  This file also contains functions to check
 * validity of the host key.
 *
 * 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".
 */

#include "includes.h"
RCSID("$OpenBSD: auth-options.c,v 1.4 2000/09/07 21:13:36 markus Exp $");

#include "ssh.h"
#include "packet.h"
#include "xmalloc.h"
#include "match.h"

/* Flags set authorized_keys flags */
int no_port_forwarding_flag = 0;
int no_agent_forwarding_flag = 0;
int no_x11_forwarding_flag = 0;
int no_pty_flag = 0;

/* "command=" option. */
char *forced_command = NULL;

/* "environment=" options. */
struct envstring *custom_environment = NULL;

/* return 1 if access is granted, 0 if not. side effect: sets key option flags */
int
auth_parse_options(struct passwd *pw, char *options, unsigned long linenum)
{
	const char *cp;
	if (!options)
		return 1;
	while (*options && *options != ' ' && *options != '\t') {
		cp = "no-port-forwarding";
		if (strncmp(options, cp, strlen(cp)) == 0) {
			packet_send_debug("Port forwarding disabled.");
			no_port_forwarding_flag = 1;
			options += strlen(cp);
			goto next_option;
		}
		cp = "no-agent-forwarding";
		if (strncmp(options, cp, strlen(cp)) == 0) {
			packet_send_debug("Agent forwarding disabled.");
			no_agent_forwarding_flag = 1;
			options += strlen(cp);
			goto next_option;
		}
		cp = "no-X11-forwarding";
		if (strncmp(options, cp, strlen(cp)) == 0) {
			packet_send_debug("X11 forwarding disabled.");
			no_x11_forwarding_flag = 1;
			options += strlen(cp);
			goto next_option;
		}
		cp = "no-pty";
		if (strncmp(options, cp, strlen(cp)) == 0) {
			packet_send_debug("Pty allocation disabled.");
			no_pty_flag = 1;
			options += strlen(cp);
			goto next_option;
		}
		cp = "command=\"";
		if (strncmp(options, cp, strlen(cp)) == 0) {
			int i;
			options += strlen(cp);
			forced_command = xmalloc(strlen(options) + 1);
			i = 0;
			while (*options) {
				if (*options == '"')
					break;
				if (*options == '\\' && options[1] == '"') {
					options += 2;
					forced_command[i++] = '"';
					continue;
				}
				forced_command[i++] = *options++;
			}
			if (!*options) {
				debug("%.100s, line %lu: missing end quote",
				      SSH_USER_PERMITTED_KEYS, linenum);
				packet_send_debug("%.100s, line %lu: missing end quote",
						  SSH_USER_PERMITTED_KEYS, linenum);
				continue;
			}
			forced_command[i] = 0;
			packet_send_debug("Forced command: %.900s", forced_command);
			options++;
			goto next_option;
		}
		cp = "environment=\"";
		if (strncmp(options, cp, strlen(cp)) == 0) {
			int i;
			char *s;
			struct envstring *new_envstring;
			options += strlen(cp);
			s = xmalloc(strlen(options) + 1);
			i = 0;
			while (*options) {
				if (*options == '"')
					break;
				if (*options == '\\' && options[1] == '"') {
					options += 2;
					s[i++] = '"';
					continue;
				}
				s[i++] = *options++;
			}
			if (!*options) {
				debug("%.100s, line %lu: missing end quote",
				      SSH_USER_PERMITTED_KEYS, linenum);
				packet_send_debug("%.100s, line %lu: missing end quote",
						  SSH_USER_PERMITTED_KEYS, linenum);
				continue;
			}
			s[i] = 0;
			packet_send_debug("Adding to environment: %.900s", s);
			debug("Adding to environment: %.900s", s);
			options++;
			new_envstring = xmalloc(sizeof(struct envstring));
			new_envstring->s = s;
			new_envstring->next = custom_environment;
			custom_environment = new_envstring;
			goto next_option;
		}
		cp = "from=\"";
		if (strncmp(options, cp, strlen(cp)) == 0) {
			int mname, mip;
			char *patterns = xmalloc(strlen(options) + 1);
			int i;
			options += strlen(cp);
			i = 0;
			while (*options) {
				if (*options == '"')
					break;
				if (*options == '\\' && options[1] == '"') {
					options += 2;
					patterns[i++] = '"';
					continue;
				}
				patterns[i++] = *options++;
			}
			if (!*options) {
				debug("%.100s, line %lu: missing end quote",
				    SSH_USER_PERMITTED_KEYS, linenum);
				packet_send_debug("%.100s, line %lu: missing end quote",
				    SSH_USER_PERMITTED_KEYS, linenum);
				continue;
			}
			patterns[i] = 0;
			options++;
			/*
			 * Deny access if we get a negative
			 * match for the hostname or the ip
			 * or if we get not match at all
			 */
			mname = match_hostname(get_canonical_hostname(),
			    patterns, strlen(patterns));
			mip = match_hostname(get_remote_ipaddr(),
			    patterns, strlen(patterns));
			xfree(patterns);
			if (mname == -1 || mip == -1 ||
			    (mname != 1 && mip != 1)) {
				log("Authentication tried for %.100s with correct key but not from a permitted host (host=%.200s, ip=%.200s).",
				    pw->pw_name, get_canonical_hostname(),
				    get_remote_ipaddr());
				packet_send_debug("Your host '%.200s' is not permitted to use this key for login.",
				get_canonical_hostname());
				/* key invalid for this host, reset flags */
				no_agent_forwarding_flag = 0;
				no_port_forwarding_flag = 0;
				no_pty_flag = 0;
				no_x11_forwarding_flag = 0;
				while (custom_environment) {
					struct envstring *ce = custom_environment;
					custom_environment = ce->next;
					xfree(ce->s);
					xfree(ce);
				}
				if (forced_command) {
					xfree(forced_command);
					forced_command = NULL;
				}
				/* deny access */
				return 0;
			}
			/* Host name matches. */
			goto next_option;
		}
next_option:
		/*
		 * Skip the comma, and move to the next option
		 * (or break out if there are no more).
		 */
		if (!*options)
			fatal("Bugs in auth-options.c option processing.");
		if (*options == ' ' || *options == '\t')
			break;		/* End of options. */
		if (*options != ',')
			goto bad_option;
		options++;
		/* Process the next option. */
	}
	/* grant access */
	return 1;

bad_option:
	log("Bad options in %.100s file, line %lu: %.50s",
	    SSH_USER_PERMITTED_KEYS, linenum, options);
	packet_send_debug("Bad options in %.100s file, line %lu: %.50s",
	    SSH_USER_PERMITTED_KEYS, linenum, options);
	/* deny access */
	return 0;
}
Commit	Line	Data
bcbf86ec	1	/*
	2	* Author: Tatu Ylonen <ylo@cs.hut.fi>
	3	* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
	4	* All rights reserved
	5	* RSA-based authentication. This code determines whether to admit a login
	6	* based on RSA authentication. This file also contains functions to check
	7	* validity of the host key.
	8	*
	9	* As far as I am concerned, the code I have written for this software
	10	* can be used freely for any purpose. Any derived versions of this
	11	* software must be clearly marked as such, and if the derived work is
	12	* incompatible with the protocol description in the RFC file, it must be
	13	* called by a name other than "ssh" or "Secure Shell".
	14	*/
	15
38c295d6	16	#include "includes.h"
bcbf86ec	17	RCSID("$OpenBSD: auth-options.c,v 1.4 2000/09/07 21:13:36 markus Exp $");
38c295d6	18
	19	#include "ssh.h"
	20	#include "packet.h"
	21	#include "xmalloc.h"
	22	#include "match.h"
	23
	24	/* Flags set authorized_keys flags */
	25	int no_port_forwarding_flag = 0;
	26	int no_agent_forwarding_flag = 0;
	27	int no_x11_forwarding_flag = 0;
	28	int no_pty_flag = 0;
	29
	30	/* "command=" option. */
	31	char *forced_command = NULL;
	32
	33	/* "environment=" options. */
	34	struct envstring *custom_environment = NULL;
	35
	36	/* return 1 if access is granted, 0 if not. side effect: sets key option flags */
	37	int
	38	auth_parse_options(struct passwd pw, char options, unsigned long linenum)
	39	{
	40	const char *cp;
	41	if (!options)
	42	return 1;
	43	while (options && options != ' ' && *options != '\t') {
	44	cp = "no-port-forwarding";
	45	if (strncmp(options, cp, strlen(cp)) == 0) {
	46	packet_send_debug("Port forwarding disabled.");
	47	no_port_forwarding_flag = 1;
	48	options += strlen(cp);
	49	goto next_option;
	50	}
	51	cp = "no-agent-forwarding";
	52	if (strncmp(options, cp, strlen(cp)) == 0) {
	53	packet_send_debug("Agent forwarding disabled.");
	54	no_agent_forwarding_flag = 1;
	55	options += strlen(cp);
	56	goto next_option;
	57	}
	58	cp = "no-X11-forwarding";
	59	if (strncmp(options, cp, strlen(cp)) == 0) {
	60	packet_send_debug("X11 forwarding disabled.");
	61	no_x11_forwarding_flag = 1;
	62	options += strlen(cp);
	63	goto next_option;
	64	}
	65	cp = "no-pty";
	66	if (strncmp(options, cp, strlen(cp)) == 0) {
	67	packet_send_debug("Pty allocation disabled.");
	68	no_pty_flag = 1;
	69	options += strlen(cp);
	70	goto next_option;
	71	}
	72	cp = "command=\"";
	73	if (strncmp(options, cp, strlen(cp)) == 0) {
	74	int i;
	75	options += strlen(cp);
	76	forced_command = xmalloc(strlen(options) + 1);
	77	i = 0;
	78	while (*options) {
	79	if (*options == '"')
	80	break;
	81	if (*options == '\\' && options[1] == '"') {
82	options += 2;
83	forced_command[i++] = '"';
84	continue;
85	}
86	forced_command[i++] = *options++;
87	}
88	if (!*options) {
89	debug("%.100s, line %lu: missing end quote",
90	SSH_USER_PERMITTED_KEYS, linenum);
91	packet_send_debug("%.100s, line %lu: missing end quote",
92	SSH_USER_PERMITTED_KEYS, linenum);
93	continue;
94	}
95	forced_command[i] = 0;
96	packet_send_debug("Forced command: %.900s", forced_command);
97	options++;
98	goto next_option;
99	}
100	cp = "environment=\"";
101	if (strncmp(options, cp, strlen(cp)) == 0) {
102	int i;
103	char *s;
104	struct envstring *new_envstring;
105	options += strlen(cp);
106	s = xmalloc(strlen(options) + 1);
107	i = 0;
108	while (*options) {
109	if (*options == '"')
110	break;
111	if (*options == '\\' && options[1] == '"') {
112	options += 2;
113	s[i++] = '"';
114	continue;
115	}
116	s[i++] = *options++;
117	}
118	if (!*options) {
119	debug("%.100s, line %lu: missing end quote",
120	SSH_USER_PERMITTED_KEYS, linenum);
121	packet_send_debug("%.100s, line %lu: missing end quote",
122	SSH_USER_PERMITTED_KEYS, linenum);
123	continue;
124	}
125	s[i] = 0;
126	packet_send_debug("Adding to environment: %.900s", s);
127	debug("Adding to environment: %.900s", s);
128	options++;
129	new_envstring = xmalloc(sizeof(struct envstring));
130	new_envstring->s = s;
131	new_envstring->next = custom_environment;
132	custom_environment = new_envstring;
133	goto next_option;
134	}
135	cp = "from=\"";
136	if (strncmp(options, cp, strlen(cp)) == 0) {
137	int mname, mip;
138	char *patterns = xmalloc(strlen(options) + 1);
139	int i;
140	options += strlen(cp);
141	i = 0;
142	while (*options) {
143	if (*options == '"')
144	break;
145	if (*options == '\\' && options[1] == '"') {
146	options += 2;
147	patterns[i++] = '"';
148	continue;
149	}
150	patterns[i++] = *options++;
151	}
152	if (!*options) {
153	debug("%.100s, line %lu: missing end quote",
154	SSH_USER_PERMITTED_KEYS, linenum);
155	packet_send_debug("%.100s, line %lu: missing end quote",
156	SSH_USER_PERMITTED_KEYS, linenum);
157	continue;
158	}
159	patterns[i] = 0;
160	options++;
161	/*
162	* Deny access if we get a negative
163	* match for the hostname or the ip
164	* or if we get not match at all
165	*/
166	mname = match_hostname(get_canonical_hostname(),
167	patterns, strlen(patterns));
168	mip = match_hostname(get_remote_ipaddr(),
169	patterns, strlen(patterns));
170	xfree(patterns);
171	if (mname == -1 \|\| mip == -1 \|\|
172	(mname != 1 && mip != 1)) {
173	log("Authentication tried for %.100s with correct key but not from a permitted host (host=%.200s, ip=%.200s).",
174	pw->pw_name, get_canonical_hostname(),
175	get_remote_ipaddr());
176	packet_send_debug("Your host '%.200s' is not permitted to use this key for login.",
177	get_canonical_hostname());
178	/* key invalid for this host, reset flags */
179	no_agent_forwarding_flag = 0;
180	no_port_forwarding_flag = 0;
181	no_pty_flag = 0;
182	no_x11_forwarding_flag = 0;
183	while (custom_environment) {
184	struct envstring *ce = custom_environment;
185	custom_environment = ce->next;
186	xfree(ce->s);
187	xfree(ce);
188	}
189	if (forced_command) {
190	xfree(forced_command);
191	forced_command = NULL;
192	}
193	/* deny access */
194	return 0;
195	}
196	/* Host name matches. */
197	goto next_option;
198	}
199	next_option:
200	/*
201	* Skip the comma, and move to the next option
202	* (or break out if there are no more).
203	*/
204	if (!*options)
205	fatal("Bugs in auth-options.c option processing.");
206	if (options == ' ' \|\| options == '\t')
207	break; /* End of options. */
208	if (*options != ',')
209	goto bad_option;
210	options++;
211	/* Process the next option. */
212	}
213	/* grant access */
214	return 1;
215
216	bad_option:
217	log("Bad options in %.100s file, line %lu: %.50s",
218	SSH_USER_PERMITTED_KEYS, linenum, options);
219	packet_send_debug("Bad options in %.100s file, line %lu: %.50s",
220	SSH_USER_PERMITTED_KEYS, linenum, options);
221	/* deny access */
222	return 0;
223	}