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1.3 deraadt 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:
1.1 markus 16: #include "includes.h"
1.7 ! markus 17: RCSID("$OpenBSD: auth-options.c,v 1.6 2000/11/15 22:31:36 markus Exp $");
1.1 markus 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:
1.5 markus 36: void
37: auth_clear_options(void)
38: {
39: no_agent_forwarding_flag = 0;
40: no_port_forwarding_flag = 0;
41: no_pty_flag = 0;
42: no_x11_forwarding_flag = 0;
43: while (custom_environment) {
44: struct envstring *ce = custom_environment;
45: custom_environment = ce->next;
46: xfree(ce->s);
47: xfree(ce);
48: }
49: if (forced_command) {
50: xfree(forced_command);
51: forced_command = NULL;
52: }
53: }
54:
1.1 markus 55: /* return 1 if access is granted, 0 if not. side effect: sets key option flags */
56: int
1.7 ! markus 57: auth_parse_options(struct passwd *pw, char *options, u_long linenum)
1.1 markus 58: {
59: const char *cp;
60: if (!options)
61: return 1;
1.5 markus 62:
63: /* reset options */
64: auth_clear_options();
65:
1.1 markus 66: while (*options && *options != ' ' && *options != '\t') {
67: cp = "no-port-forwarding";
1.6 markus 68: if (strncasecmp(options, cp, strlen(cp)) == 0) {
1.1 markus 69: packet_send_debug("Port forwarding disabled.");
70: no_port_forwarding_flag = 1;
71: options += strlen(cp);
72: goto next_option;
73: }
74: cp = "no-agent-forwarding";
1.6 markus 75: if (strncasecmp(options, cp, strlen(cp)) == 0) {
1.1 markus 76: packet_send_debug("Agent forwarding disabled.");
77: no_agent_forwarding_flag = 1;
78: options += strlen(cp);
79: goto next_option;
80: }
81: cp = "no-X11-forwarding";
1.6 markus 82: if (strncasecmp(options, cp, strlen(cp)) == 0) {
1.1 markus 83: packet_send_debug("X11 forwarding disabled.");
84: no_x11_forwarding_flag = 1;
85: options += strlen(cp);
86: goto next_option;
87: }
88: cp = "no-pty";
1.6 markus 89: if (strncasecmp(options, cp, strlen(cp)) == 0) {
1.1 markus 90: packet_send_debug("Pty allocation disabled.");
91: no_pty_flag = 1;
92: options += strlen(cp);
93: goto next_option;
94: }
95: cp = "command=\"";
1.6 markus 96: if (strncasecmp(options, cp, strlen(cp)) == 0) {
1.1 markus 97: int i;
98: options += strlen(cp);
99: forced_command = xmalloc(strlen(options) + 1);
100: i = 0;
101: while (*options) {
102: if (*options == '"')
103: break;
104: if (*options == '\\' && options[1] == '"') {
105: options += 2;
106: forced_command[i++] = '"';
107: continue;
108: }
109: forced_command[i++] = *options++;
110: }
111: if (!*options) {
112: debug("%.100s, line %lu: missing end quote",
1.5 markus 113: SSH_USER_PERMITTED_KEYS, linenum);
1.1 markus 114: packet_send_debug("%.100s, line %lu: missing end quote",
1.5 markus 115: SSH_USER_PERMITTED_KEYS, linenum);
1.1 markus 116: continue;
117: }
118: forced_command[i] = 0;
119: packet_send_debug("Forced command: %.900s", forced_command);
120: options++;
121: goto next_option;
122: }
123: cp = "environment=\"";
1.6 markus 124: if (strncasecmp(options, cp, strlen(cp)) == 0) {
1.1 markus 125: int i;
126: char *s;
127: struct envstring *new_envstring;
128: options += strlen(cp);
129: s = xmalloc(strlen(options) + 1);
130: i = 0;
131: while (*options) {
132: if (*options == '"')
133: break;
134: if (*options == '\\' && options[1] == '"') {
135: options += 2;
136: s[i++] = '"';
137: continue;
138: }
139: s[i++] = *options++;
140: }
141: if (!*options) {
142: debug("%.100s, line %lu: missing end quote",
1.5 markus 143: SSH_USER_PERMITTED_KEYS, linenum);
1.1 markus 144: packet_send_debug("%.100s, line %lu: missing end quote",
1.5 markus 145: SSH_USER_PERMITTED_KEYS, linenum);
1.1 markus 146: continue;
147: }
148: s[i] = 0;
149: packet_send_debug("Adding to environment: %.900s", s);
150: debug("Adding to environment: %.900s", s);
151: options++;
152: new_envstring = xmalloc(sizeof(struct envstring));
153: new_envstring->s = s;
154: new_envstring->next = custom_environment;
155: custom_environment = new_envstring;
156: goto next_option;
157: }
158: cp = "from=\"";
1.6 markus 159: if (strncasecmp(options, cp, strlen(cp)) == 0) {
1.1 markus 160: int mname, mip;
161: char *patterns = xmalloc(strlen(options) + 1);
162: int i;
163: options += strlen(cp);
164: i = 0;
165: while (*options) {
166: if (*options == '"')
167: break;
168: if (*options == '\\' && options[1] == '"') {
169: options += 2;
170: patterns[i++] = '"';
171: continue;
172: }
173: patterns[i++] = *options++;
174: }
175: if (!*options) {
176: debug("%.100s, line %lu: missing end quote",
177: SSH_USER_PERMITTED_KEYS, linenum);
178: packet_send_debug("%.100s, line %lu: missing end quote",
179: SSH_USER_PERMITTED_KEYS, linenum);
180: continue;
181: }
182: patterns[i] = 0;
183: options++;
184: /*
185: * Deny access if we get a negative
186: * match for the hostname or the ip
187: * or if we get not match at all
188: */
189: mname = match_hostname(get_canonical_hostname(),
190: patterns, strlen(patterns));
191: mip = match_hostname(get_remote_ipaddr(),
192: patterns, strlen(patterns));
193: xfree(patterns);
194: if (mname == -1 || mip == -1 ||
195: (mname != 1 && mip != 1)) {
196: log("Authentication tried for %.100s with correct key but not from a permitted host (host=%.200s, ip=%.200s).",
197: pw->pw_name, get_canonical_hostname(),
198: get_remote_ipaddr());
199: packet_send_debug("Your host '%.200s' is not permitted to use this key for login.",
200: get_canonical_hostname());
201: /* deny access */
202: return 0;
203: }
204: /* Host name matches. */
205: goto next_option;
206: }
207: next_option:
208: /*
209: * Skip the comma, and move to the next option
210: * (or break out if there are no more).
211: */
212: if (!*options)
213: fatal("Bugs in auth-options.c option processing.");
214: if (*options == ' ' || *options == '\t')
215: break; /* End of options. */
216: if (*options != ',')
217: goto bad_option;
218: options++;
219: /* Process the next option. */
220: }
221: /* grant access */
222: return 1;
223:
224: bad_option:
225: log("Bad options in %.100s file, line %lu: %.50s",
226: SSH_USER_PERMITTED_KEYS, linenum, options);
227: packet_send_debug("Bad options in %.100s file, line %lu: %.50s",
228: SSH_USER_PERMITTED_KEYS, linenum, options);
229: /* deny access */
230: return 0;
231: }