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b12be54a RK |
1 | /* |
2 | * This file is part of DisOrder | |
3 | * Copyright (C) 2007 Richard Kettlewell | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify | |
6 | * it under the terms of the GNU General Public License as published by | |
7 | * the Free Software Foundation; either version 2 of the License, or | |
8 | * (at your option) any later version. | |
9 | * | |
10 | * This program is distributed in the hope that it will be useful, but | |
11 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 | * General Public License for more details. | |
14 | * | |
15 | * You should have received a copy of the GNU General Public License | |
16 | * along with this program; if not, write to the Free Software | |
17 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 | |
18 | * USA | |
19 | */ | |
20 | /** @file lib/cookies.c | |
21 | * @brief Cookie support | |
22 | */ | |
23 | ||
24 | #include <config.h> | |
25 | #include "types.h" | |
26 | ||
27 | #include <stdlib.h> | |
28 | #include <string.h> | |
29 | #include <stdio.h> | |
30 | #include <errno.h> | |
31 | #include <time.h> | |
32 | #include <gcrypt.h> | |
f0feb22e | 33 | #include <pcre.h> |
b12be54a | 34 | |
eb5dc014 | 35 | #include "rights.h" |
b12be54a RK |
36 | #include "cookies.h" |
37 | #include "hash.h" | |
38 | #include "mem.h" | |
39 | #include "log.h" | |
40 | #include "printf.h" | |
fce810c2 | 41 | #include "base64.h" |
b12be54a RK |
42 | #include "configuration.h" |
43 | #include "kvp.h" | |
5df73aeb | 44 | #include "rights.h" |
f0feb22e | 45 | #include "trackdb.h" |
b12be54a RK |
46 | |
47 | /** @brief Hash function used in signing HMAC */ | |
48 | #define ALGO GCRY_MD_SHA1 | |
49 | ||
50 | /** @brief Size of key to use */ | |
51 | #define HASHSIZE 20 | |
52 | ||
53 | /** @brief Signing key */ | |
54 | static uint8_t signing_key[HASHSIZE]; | |
55 | ||
56 | /** @brief Previous signing key */ | |
57 | static uint8_t old_signing_key[HASHSIZE]; | |
58 | ||
59 | /** @brief Signing key validity limit or 0 if none */ | |
60 | static time_t signing_key_validity_limit; | |
61 | ||
62 | /** @brief Hash of revoked cookies */ | |
63 | static hash *revoked; | |
64 | ||
65 | /** @brief Callback to expire revocation list */ | |
66 | static int revoked_cleanup_callback(const char *key, void *value, | |
67 | void *u) { | |
68 | if(*(time_t *)value < *(time_t *)u) | |
69 | hash_remove(revoked, key); | |
70 | return 0; | |
71 | } | |
72 | ||
73 | /** @brief Generate a new key */ | |
74 | static void newkey(void) { | |
75 | time_t now; | |
76 | ||
77 | time(&now); | |
78 | memcpy(old_signing_key, signing_key, HASHSIZE); | |
79 | gcry_randomize(signing_key, HASHSIZE, GCRY_STRONG_RANDOM); | |
80 | signing_key_validity_limit = now + config->cookie_key_lifetime; | |
81 | /* Now is a good time to clean up the revocation list... */ | |
82 | if(revoked) | |
83 | hash_foreach(revoked, revoked_cleanup_callback, &now); | |
84 | } | |
85 | ||
86 | /** @brief Sign @p subject with @p key and return the base64 of the result | |
87 | * @param key Key to sign with (@ref HASHSIZE bytes) | |
88 | * @param subject Subject string | |
89 | * @return Base64-encoded signature or NULL | |
90 | */ | |
91 | static char *sign(const uint8_t *key, | |
92 | const char *subject) { | |
93 | gcry_error_t e; | |
94 | gcry_md_hd_t h; | |
95 | uint8_t *sig; | |
96 | char *sig64; | |
97 | ||
98 | if((e = gcry_md_open(&h, ALGO, GCRY_MD_FLAG_HMAC))) { | |
99 | error(0, "gcry_md_open: %s", gcry_strerror(e)); | |
100 | return 0; | |
101 | } | |
102 | if((e = gcry_md_setkey(h, key, HASHSIZE))) { | |
103 | error(0, "gcry_md_setkey: %s", gcry_strerror(e)); | |
104 | gcry_md_close(h); | |
105 | return 0; | |
106 | } | |
107 | gcry_md_write(h, subject, strlen(subject)); | |
108 | sig = gcry_md_read(h, ALGO); | |
109 | sig64 = mime_to_base64(sig, HASHSIZE); | |
110 | gcry_md_close(h); | |
111 | return sig64; | |
112 | } | |
113 | ||
114 | /** @brief Create a login cookie | |
115 | * @param user Username | |
116 | * @return Cookie or NULL | |
117 | */ | |
118 | char *make_cookie(const char *user) { | |
f0feb22e | 119 | const char *password; |
b12be54a RK |
120 | time_t now; |
121 | char *b, *bp, *c, *g; | |
b12be54a RK |
122 | |
123 | /* semicolons aren't allowed in usernames */ | |
124 | if(strchr(user, ';')) { | |
125 | error(0, "make_cookie for username with semicolon"); | |
126 | return 0; | |
127 | } | |
128 | /* look up the password */ | |
f0feb22e RK |
129 | password = trackdb_get_password(user); |
130 | if(!password) { | |
b12be54a RK |
131 | error(0, "make_cookie for nonexistent user"); |
132 | return 0; | |
133 | } | |
b12be54a RK |
134 | /* make sure we have a valid signing key */ |
135 | time(&now); | |
136 | if(now >= signing_key_validity_limit) | |
137 | newkey(); | |
138 | /* construct the subject */ | |
139 | byte_xasprintf(&b, "%jx;%s;", (intmax_t)now + config->cookie_login_lifetime, | |
140 | urlencodestring(user)); | |
141 | byte_xasprintf(&bp, "%s%s", b, password); | |
142 | /* sign it */ | |
143 | if(!(g = sign(signing_key, bp))) | |
144 | return 0; | |
145 | /* put together the final cookie */ | |
146 | byte_xasprintf(&c, "%s%s", b, g); | |
147 | return c; | |
148 | } | |
149 | ||
150 | /** @brief Verify a cookie | |
151 | * @param cookie Cookie to verify | |
eb5dc014 | 152 | * @param rights Where to store rights value |
b12be54a RK |
153 | * @return Verified user or NULL |
154 | */ | |
eb5dc014 | 155 | char *verify_cookie(const char *cookie, rights_type *rights) { |
b12be54a RK |
156 | char *c1, *c2; |
157 | intmax_t t; | |
158 | time_t now; | |
f0feb22e RK |
159 | char *user, *bp, *sig; |
160 | const char *password; | |
eb5dc014 | 161 | struct kvp *k; |
b12be54a RK |
162 | |
163 | /* check the revocation list */ | |
164 | if(revoked && hash_find(revoked, cookie)) { | |
165 | error(0, "attempt to log in with revoked cookie"); | |
166 | return 0; | |
167 | } | |
168 | /* parse the cookie */ | |
169 | errno = 0; | |
170 | t = strtoimax(cookie, &c1, 16); | |
171 | if(errno) { | |
172 | error(errno, "error parsing cookie timestamp"); | |
173 | return 0; | |
174 | } | |
175 | if(*c1 != ';') { | |
176 | error(0, "invalid cookie timestamp"); | |
177 | return 0; | |
178 | } | |
179 | /* There'd better be two semicolons */ | |
180 | c2 = strchr(c1 + 1, ';'); | |
181 | if(c2 == 0) { | |
182 | error(0, "invalid cookie syntax"); | |
183 | return 0; | |
184 | } | |
185 | /* Extract the username */ | |
186 | user = xstrndup(c1 + 1, c2 - (c1 + 1)); | |
187 | /* check expiry */ | |
188 | time(&now); | |
189 | if(now >= t) { | |
190 | error(0, "cookie has expired"); | |
191 | return 0; | |
192 | } | |
193 | /* look up the password */ | |
eb5dc014 RK |
194 | k = trackdb_getuserinfo(user); |
195 | if(!k) { | |
b12be54a RK |
196 | error(0, "verify_cookie for nonexistent user"); |
197 | return 0; | |
198 | } | |
eb5dc014 RK |
199 | password = kvp_get(k, "password"); |
200 | if(!password) password = ""; | |
0f55e905 | 201 | if(parse_rights(kvp_get(k, "rights"), rights, 1)) |
eb5dc014 | 202 | return 0; |
b12be54a RK |
203 | /* construct the expected subject. We re-encode the timestamp and the |
204 | * password. */ | |
205 | byte_xasprintf(&bp, "%jx;%s;%s", t, urlencodestring(user), password); | |
206 | /* Compute the expected signature. NB we base64 the expected signature and | |
207 | * compare that rather than exposing our base64 parser to the cookie. */ | |
208 | if(!(sig = sign(signing_key, bp))) | |
209 | return 0; | |
210 | if(!strcmp(sig, c2 + 1)) | |
211 | return user; | |
212 | /* that didn't match, try the old key */ | |
213 | if(!(sig = sign(old_signing_key, bp))) | |
214 | return 0; | |
215 | if(!strcmp(sig, c2 + 1)) | |
216 | return user; | |
217 | /* that didn't match either */ | |
218 | error(0, "cookie signature does not match"); | |
219 | return 0; | |
220 | } | |
221 | ||
222 | /** @brief Revoke a cookie | |
223 | * @param cookie Cookie to revoke | |
224 | * | |
225 | * Further attempts to log in with @p cookie will fail. | |
226 | */ | |
227 | void revoke_cookie(const char *cookie) { | |
228 | time_t when; | |
229 | char *ptr; | |
230 | ||
231 | /* find the cookie's expiry time */ | |
232 | errno = 0; | |
233 | when = (time_t)strtoimax(cookie, &ptr, 16); | |
234 | /* reject bogus cookies */ | |
235 | if(errno) | |
236 | return; | |
237 | if(*ptr != ';') | |
238 | return; | |
239 | /* make sure the revocation list exists */ | |
240 | if(!revoked) | |
241 | revoked = hash_new(sizeof(time_t)); | |
242 | /* add the cookie to it; its value is the expiry time */ | |
243 | hash_add(revoked, cookie, &when, HASH_INSERT); | |
244 | } | |
245 | ||
246 | /* | |
247 | Local Variables: | |
248 | c-basic-offset:2 | |
249 | comment-column:40 | |
250 | fill-column:79 | |
251 | indent-tabs-mode:nil | |
252 | End: | |
253 | */ |