diff options
author | Ben Lindstrom <mouring@eviladmin.org> | 2002-06-06 20:27:55 +0000 |
---|---|---|
committer | Ben Lindstrom <mouring@eviladmin.org> | 2002-06-06 20:27:55 +0000 |
commit | 855bf3ac3cf395b282600700c1fd792af1f3fdcb (patch) | |
tree | effce712ac4bb1d7ef46cc3db4fdda2b74756298 /auth2-pubkey.c | |
parent | 4887da222b5dec4e36f85f724d836dfbb6d434c7 (diff) |
- markus@cvs.openbsd.org 2002/05/25 18:51:07
[auth.h auth2.c auth2-hostbased.c auth2-kbdint.c auth2-none.c
auth2-passwd.c auth2-pubkey.c Makefile.in]
split auth2.c into one file per method; ok provos@/deraadt@
NOTE: Merged back noticable cygwin and pam stuff. May need review to
ensure I did not miss anything.
Diffstat (limited to 'auth2-pubkey.c')
-rw-r--r-- | auth2-pubkey.c | 283 |
1 files changed, 283 insertions, 0 deletions
diff --git a/auth2-pubkey.c b/auth2-pubkey.c new file mode 100644 index 000000000..947bfed0b --- /dev/null +++ b/auth2-pubkey.c | |||
@@ -0,0 +1,283 @@ | |||
1 | /* | ||
2 | * Copyright (c) 2000 Markus Friedl. All rights reserved. | ||
3 | * | ||
4 | * Redistribution and use in source and binary forms, with or without | ||
5 | * modification, are permitted provided that the following conditions | ||
6 | * are met: | ||
7 | * 1. Redistributions of source code must retain the above copyright | ||
8 | * notice, this list of conditions and the following disclaimer. | ||
9 | * 2. Redistributions in binary form must reproduce the above copyright | ||
10 | * notice, this list of conditions and the following disclaimer in the | ||
11 | * documentation and/or other materials provided with the distribution. | ||
12 | * | ||
13 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | ||
14 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | ||
15 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | ||
16 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | ||
17 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | ||
18 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | ||
19 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | ||
20 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | ||
21 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | ||
22 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | ||
23 | */ | ||
24 | |||
25 | #include "includes.h" | ||
26 | RCSID("$OpenBSD: auth2-pubkey.c,v 1.2 2002/05/31 11:35:15 markus Exp $"); | ||
27 | |||
28 | #include "ssh2.h" | ||
29 | #include "xmalloc.h" | ||
30 | #include "packet.h" | ||
31 | #include "buffer.h" | ||
32 | #include "log.h" | ||
33 | #include "servconf.h" | ||
34 | #include "compat.h" | ||
35 | #include "bufaux.h" | ||
36 | #include "auth.h" | ||
37 | #include "key.h" | ||
38 | #include "pathnames.h" | ||
39 | #include "uidswap.h" | ||
40 | #include "auth-options.h" | ||
41 | #include "canohost.h" | ||
42 | #include "monitor_wrap.h" | ||
43 | |||
44 | /* import */ | ||
45 | extern ServerOptions options; | ||
46 | extern u_char *session_id2; | ||
47 | extern int session_id2_len; | ||
48 | |||
49 | static int | ||
50 | userauth_pubkey(Authctxt *authctxt) | ||
51 | { | ||
52 | Buffer b; | ||
53 | Key *key = NULL; | ||
54 | char *pkalg; | ||
55 | u_char *pkblob, *sig; | ||
56 | u_int alen, blen, slen; | ||
57 | int have_sig, pktype; | ||
58 | int authenticated = 0; | ||
59 | |||
60 | if (!authctxt->valid) { | ||
61 | debug2("userauth_pubkey: disabled because of invalid user"); | ||
62 | return 0; | ||
63 | } | ||
64 | have_sig = packet_get_char(); | ||
65 | if (datafellows & SSH_BUG_PKAUTH) { | ||
66 | debug2("userauth_pubkey: SSH_BUG_PKAUTH"); | ||
67 | /* no explicit pkalg given */ | ||
68 | pkblob = packet_get_string(&blen); | ||
69 | buffer_init(&b); | ||
70 | buffer_append(&b, pkblob, blen); | ||
71 | /* so we have to extract the pkalg from the pkblob */ | ||
72 | pkalg = buffer_get_string(&b, &alen); | ||
73 | buffer_free(&b); | ||
74 | } else { | ||
75 | pkalg = packet_get_string(&alen); | ||
76 | pkblob = packet_get_string(&blen); | ||
77 | } | ||
78 | pktype = key_type_from_name(pkalg); | ||
79 | if (pktype == KEY_UNSPEC) { | ||
80 | /* this is perfectly legal */ | ||
81 | log("userauth_pubkey: unsupported public key algorithm: %s", | ||
82 | pkalg); | ||
83 | goto done; | ||
84 | } | ||
85 | key = key_from_blob(pkblob, blen); | ||
86 | if (key == NULL) { | ||
87 | error("userauth_pubkey: cannot decode key: %s", pkalg); | ||
88 | goto done; | ||
89 | } | ||
90 | if (key->type != pktype) { | ||
91 | error("userauth_pubkey: type mismatch for decoded key " | ||
92 | "(received %d, expected %d)", key->type, pktype); | ||
93 | goto done; | ||
94 | } | ||
95 | if (have_sig) { | ||
96 | sig = packet_get_string(&slen); | ||
97 | packet_check_eom(); | ||
98 | buffer_init(&b); | ||
99 | if (datafellows & SSH_OLD_SESSIONID) { | ||
100 | buffer_append(&b, session_id2, session_id2_len); | ||
101 | } else { | ||
102 | buffer_put_string(&b, session_id2, session_id2_len); | ||
103 | } | ||
104 | /* reconstruct packet */ | ||
105 | buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); | ||
106 | buffer_put_cstring(&b, authctxt->user); | ||
107 | buffer_put_cstring(&b, | ||
108 | datafellows & SSH_BUG_PKSERVICE ? | ||
109 | "ssh-userauth" : | ||
110 | authctxt->service); | ||
111 | if (datafellows & SSH_BUG_PKAUTH) { | ||
112 | buffer_put_char(&b, have_sig); | ||
113 | } else { | ||
114 | buffer_put_cstring(&b, "publickey"); | ||
115 | buffer_put_char(&b, have_sig); | ||
116 | buffer_put_cstring(&b, pkalg); | ||
117 | } | ||
118 | buffer_put_string(&b, pkblob, blen); | ||
119 | #ifdef DEBUG_PK | ||
120 | buffer_dump(&b); | ||
121 | #endif | ||
122 | /* test for correct signature */ | ||
123 | authenticated = 0; | ||
124 | if (PRIVSEP(user_key_allowed(authctxt->pw, key)) && | ||
125 | PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b), | ||
126 | buffer_len(&b))) == 1) | ||
127 | authenticated = 1; | ||
128 | buffer_clear(&b); | ||
129 | xfree(sig); | ||
130 | } else { | ||
131 | debug("test whether pkalg/pkblob are acceptable"); | ||
132 | packet_check_eom(); | ||
133 | |||
134 | /* XXX fake reply and always send PK_OK ? */ | ||
135 | /* | ||
136 | * XXX this allows testing whether a user is allowed | ||
137 | * to login: if you happen to have a valid pubkey this | ||
138 | * message is sent. the message is NEVER sent at all | ||
139 | * if a user is not allowed to login. is this an | ||
140 | * issue? -markus | ||
141 | */ | ||
142 | if (PRIVSEP(user_key_allowed(authctxt->pw, key))) { | ||
143 | packet_start(SSH2_MSG_USERAUTH_PK_OK); | ||
144 | packet_put_string(pkalg, alen); | ||
145 | packet_put_string(pkblob, blen); | ||
146 | packet_send(); | ||
147 | packet_write_wait(); | ||
148 | authctxt->postponed = 1; | ||
149 | } | ||
150 | } | ||
151 | if (authenticated != 1) | ||
152 | auth_clear_options(); | ||
153 | done: | ||
154 | debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg); | ||
155 | if (key != NULL) | ||
156 | key_free(key); | ||
157 | xfree(pkalg); | ||
158 | xfree(pkblob); | ||
159 | #ifdef HAVE_CYGWIN | ||
160 | if (check_nt_auth(0, authctxt->pw) == 0) | ||
161 | return(0); | ||
162 | #endif | ||
163 | return authenticated; | ||
164 | } | ||
165 | |||
166 | /* return 1 if user allows given key */ | ||
167 | static int | ||
168 | user_key_allowed2(struct passwd *pw, Key *key, char *file) | ||
169 | { | ||
170 | char line[8192]; | ||
171 | int found_key = 0; | ||
172 | FILE *f; | ||
173 | u_long linenum = 0; | ||
174 | struct stat st; | ||
175 | Key *found; | ||
176 | char *fp; | ||
177 | |||
178 | if (pw == NULL) | ||
179 | return 0; | ||
180 | |||
181 | /* Temporarily use the user's uid. */ | ||
182 | temporarily_use_uid(pw); | ||
183 | |||
184 | debug("trying public key file %s", file); | ||
185 | |||
186 | /* Fail quietly if file does not exist */ | ||
187 | if (stat(file, &st) < 0) { | ||
188 | /* Restore the privileged uid. */ | ||
189 | restore_uid(); | ||
190 | return 0; | ||
191 | } | ||
192 | /* Open the file containing the authorized keys. */ | ||
193 | f = fopen(file, "r"); | ||
194 | if (!f) { | ||
195 | /* Restore the privileged uid. */ | ||
196 | restore_uid(); | ||
197 | return 0; | ||
198 | } | ||
199 | if (options.strict_modes && | ||
200 | secure_filename(f, file, pw, line, sizeof(line)) != 0) { | ||
201 | fclose(f); | ||
202 | log("Authentication refused: %s", line); | ||
203 | restore_uid(); | ||
204 | return 0; | ||
205 | } | ||
206 | |||
207 | found_key = 0; | ||
208 | found = key_new(key->type); | ||
209 | |||
210 | while (fgets(line, sizeof(line), f)) { | ||
211 | char *cp, *options = NULL; | ||
212 | linenum++; | ||
213 | /* Skip leading whitespace, empty and comment lines. */ | ||
214 | for (cp = line; *cp == ' ' || *cp == '\t'; cp++) | ||
215 | ; | ||
216 | if (!*cp || *cp == '\n' || *cp == '#') | ||
217 | continue; | ||
218 | |||
219 | if (key_read(found, &cp) != 1) { | ||
220 | /* no key? check if there are options for this key */ | ||
221 | int quoted = 0; | ||
222 | debug2("user_key_allowed: check options: '%s'", cp); | ||
223 | options = cp; | ||
224 | for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) { | ||
225 | if (*cp == '\\' && cp[1] == '"') | ||
226 | cp++; /* Skip both */ | ||
227 | else if (*cp == '"') | ||
228 | quoted = !quoted; | ||
229 | } | ||
230 | /* Skip remaining whitespace. */ | ||
231 | for (; *cp == ' ' || *cp == '\t'; cp++) | ||
232 | ; | ||
233 | if (key_read(found, &cp) != 1) { | ||
234 | debug2("user_key_allowed: advance: '%s'", cp); | ||
235 | /* still no key? advance to next line*/ | ||
236 | continue; | ||
237 | } | ||
238 | } | ||
239 | if (key_equal(found, key) && | ||
240 | auth_parse_options(pw, options, file, linenum) == 1) { | ||
241 | found_key = 1; | ||
242 | debug("matching key found: file %s, line %lu", | ||
243 | file, linenum); | ||
244 | fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX); | ||
245 | verbose("Found matching %s key: %s", | ||
246 | key_type(found), fp); | ||
247 | xfree(fp); | ||
248 | break; | ||
249 | } | ||
250 | } | ||
251 | restore_uid(); | ||
252 | fclose(f); | ||
253 | key_free(found); | ||
254 | if (!found_key) | ||
255 | debug2("key not found"); | ||
256 | return found_key; | ||
257 | } | ||
258 | |||
259 | /* check whether given key is in .ssh/authorized_keys* */ | ||
260 | int | ||
261 | user_key_allowed(struct passwd *pw, Key *key) | ||
262 | { | ||
263 | int success; | ||
264 | char *file; | ||
265 | |||
266 | file = authorized_keys_file(pw); | ||
267 | success = user_key_allowed2(pw, key, file); | ||
268 | xfree(file); | ||
269 | if (success) | ||
270 | return success; | ||
271 | |||
272 | /* try suffix "2" for backward compat, too */ | ||
273 | file = authorized_keys_file2(pw); | ||
274 | success = user_key_allowed2(pw, key, file); | ||
275 | xfree(file); | ||
276 | return success; | ||
277 | } | ||
278 | |||
279 | Authmethod method_pubkey = { | ||
280 | "publickey", | ||
281 | userauth_pubkey, | ||
282 | &options.pubkey_authentication | ||
283 | }; | ||