Adding a support script that can be used to make the checked-out
[rsync/rsync.git] / authenticate.c
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1/*
2 * Support rsync daemon authentication.
3 *
4 * Copyright (C) 1998-2000 Andrew Tridgell
5 * Copyright (C) 2002-2007 Wayne Davison
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 3 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License along
18 * with this program; if not, visit the http://fsf.org website.
19 */
20
21#include "rsync.h"
22
23extern char *password_file;
24extern int log_got_error;
25
26/***************************************************************************
27encode a buffer using base64 - simple and slow algorithm. null terminates
28the result.
29 ***************************************************************************/
30void base64_encode(const char *buf, int len, char *out, int pad)
31{
32 char *b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
33 int bit_offset, byte_offset, idx, i;
34 const uchar *d = (const uchar *)buf;
35 int bytes = (len*8 + 5)/6;
36
37 for (i = 0; i < bytes; i++) {
38 byte_offset = (i*6)/8;
39 bit_offset = (i*6)%8;
40 if (bit_offset < 3) {
41 idx = (d[byte_offset] >> (2-bit_offset)) & 0x3F;
42 } else {
43 idx = (d[byte_offset] << (bit_offset-2)) & 0x3F;
44 if (byte_offset+1 < len) {
45 idx |= (d[byte_offset+1] >> (8-(bit_offset-2)));
46 }
47 }
48 out[i] = b64[idx];
49 }
50
51 while (pad && (i % 4))
52 out[i++] = '=';
53
54 out[i] = '\0';
55}
56
57/* Generate a challenge buffer and return it base64-encoded. */
58static void gen_challenge(const char *addr, char *challenge)
59{
60 char input[32];
61 char digest[MAX_DIGEST_LEN];
62 struct timeval tv;
63 int len;
64
65 memset(input, 0, sizeof input);
66
67 strlcpy(input, addr, 17);
68 sys_gettimeofday(&tv);
69 SIVAL(input, 16, tv.tv_sec);
70 SIVAL(input, 20, tv.tv_usec);
71 SIVAL(input, 24, getpid());
72
73 sum_init(0);
74 sum_update(input, sizeof input);
75 len = sum_end(digest);
76
77 base64_encode(digest, len, challenge, 0);
78}
79
80
81/* Return the secret for a user from the secret file, null terminated.
82 * Maximum length is len (not counting the null). */
83static int get_secret(int module, const char *user, char *secret, int len)
84{
85 const char *fname = lp_secrets_file(module);
86 STRUCT_STAT st;
87 int fd, ok = 1;
88 const char *p;
89 char ch, *s;
90
91 if (!fname || !*fname)
92 return 0;
93
94 if ((fd = open(fname, O_RDONLY)) < 0)
95 return 0;
96
97 if (do_stat(fname, &st) == -1) {
98 rsyserr(FLOG, errno, "stat(%s)", fname);
99 ok = 0;
100 } else if (lp_strict_modes(module)) {
101 if ((st.st_mode & 06) != 0) {
102 rprintf(FLOG, "secrets file must not be other-accessible (see strict modes option)\n");
103 ok = 0;
104 } else if (MY_UID() == 0 && st.st_uid != 0) {
105 rprintf(FLOG, "secrets file must be owned by root when running as root (see strict modes)\n");
106 ok = 0;
107 }
108 }
109 if (!ok) {
110 rprintf(FLOG, "continuing without secrets file\n");
111 close(fd);
112 return 0;
113 }
114
115 if (*user == '#') {
116 /* Reject attempt to match a comment. */
117 close(fd);
118 return 0;
119 }
120
121 /* Try to find a line that starts with the user name and a ':'. */
122 p = user;
123 while (1) {
124 if (read(fd, &ch, 1) != 1) {
125 close(fd);
126 return 0;
127 }
128 if (ch == '\n')
129 p = user;
130 else if (p) {
131 if (*p == ch)
132 p++;
133 else if (!*p && ch == ':')
134 break;
135 else
136 p = NULL;
137 }
138 }
139
140 /* Slurp the secret into the "secret" buffer. */
141 s = secret;
142 while (len > 0) {
143 if (read(fd, s, 1) != 1 || *s == '\n')
144 break;
145 if (*s == '\r')
146 continue;
147 s++;
148 len--;
149 }
150 *s = '\0';
151 close(fd);
152
153 return 1;
154}
155
156static const char *getpassf(const char *filename)
157{
158 STRUCT_STAT st;
159 char buffer[512], *p;
160 int fd, n, ok = 1;
161 const char *envpw = getenv("RSYNC_PASSWORD");
162
163 if (!filename)
164 return NULL;
165
166 if ((fd = open(filename,O_RDONLY)) < 0) {
167 rsyserr(FERROR, errno, "could not open password file \"%s\"",
168 filename);
169 if (envpw)
170 rprintf(FINFO, "falling back to RSYNC_PASSWORD environment variable.\n");
171 return NULL;
172 }
173
174 if (do_stat(filename, &st) == -1) {
175 rsyserr(FERROR, errno, "stat(%s)", filename);
176 ok = 0;
177 } else if ((st.st_mode & 06) != 0) {
178 rprintf(FERROR, "password file must not be other-accessible\n");
179 ok = 0;
180 } else if (MY_UID() == 0 && st.st_uid != 0) {
181 rprintf(FERROR, "password file must be owned by root when running as root\n");
182 ok = 0;
183 }
184 if (!ok) {
185 close(fd);
186 rprintf(FERROR, "continuing without password file\n");
187 if (envpw)
188 rprintf(FINFO, "falling back to RSYNC_PASSWORD environment variable.\n");
189 return NULL;
190 }
191
192 n = read(fd, buffer, sizeof buffer - 1);
193 close(fd);
194 if (n > 0) {
195 buffer[n] = '\0';
196 if ((p = strtok(buffer, "\n\r")) != NULL)
197 return strdup(p);
198 }
199
200 return NULL;
201}
202
203/* Generate an MD4 hash created from the combination of the password
204 * and the challenge string and return it base64-encoded. */
205static void generate_hash(const char *in, const char *challenge, char *out)
206{
207 char buf[MAX_DIGEST_LEN];
208 int len;
209
210 sum_init(0);
211 sum_update(in, strlen(in));
212 sum_update(challenge, strlen(challenge));
213 len = sum_end(buf);
214
215 base64_encode(buf, len, out, 0);
216}
217
218/* Possibly negotiate authentication with the client. Use "leader" to
219 * start off the auth if necessary.
220 *
221 * Return NULL if authentication failed. Return "" if anonymous access.
222 * Otherwise return username.
223 */
224char *auth_server(int f_in, int f_out, int module, const char *host,
225 const char *addr, const char *leader)
226{
227 char *users = lp_auth_users(module);
228 char challenge[MAX_DIGEST_LEN*2];
229 char line[BIGPATHBUFLEN];
230 char secret[512];
231 char pass2[MAX_DIGEST_LEN*2];
232 char *tok, *pass;
233
234 /* if no auth list then allow anyone in! */
235 if (!users || !*users)
236 return "";
237
238 gen_challenge(addr, challenge);
239
240 io_printf(f_out, "%s%s\n", leader, challenge);
241
242 if (!read_line_old(f_in, line, sizeof line)
243 || (pass = strchr(line, ' ')) == NULL) {
244 rprintf(FLOG, "auth failed on module %s from %s (%s): "
245 "invalid challenge response\n",
246 lp_name(module), host, addr);
247 return NULL;
248 }
249 *pass++ = '\0';
250
251 if (!(users = strdup(users)))
252 out_of_memory("auth_server");
253
254 for (tok = strtok(users, " ,\t"); tok; tok = strtok(NULL, " ,\t")) {
255 if (wildmatch(tok, line))
256 break;
257 }
258 free(users);
259
260 if (!tok) {
261 rprintf(FLOG, "auth failed on module %s from %s (%s): "
262 "unauthorized user\n",
263 lp_name(module), host, addr);
264 return NULL;
265 }
266
267 memset(secret, 0, sizeof secret);
268 if (!get_secret(module, line, secret, sizeof secret - 1)) {
269 memset(secret, 0, sizeof secret);
270 rprintf(FLOG, "auth failed on module %s from %s (%s): "
271 "missing secret for user \"%s\"\n",
272 lp_name(module), host, addr, line);
273 return NULL;
274 }
275
276 generate_hash(secret, challenge, pass2);
277 memset(secret, 0, sizeof secret);
278
279 if (strcmp(pass, pass2) != 0) {
280 rprintf(FLOG, "auth failed on module %s from %s (%s): "
281 "password mismatch\n",
282 lp_name(module), host, addr);
283 return NULL;
284 }
285
286 return strdup(line);
287}
288
289void auth_client(int fd, const char *user, const char *challenge)
290{
291 const char *pass;
292 char pass2[MAX_DIGEST_LEN*2];
293
294 if (!user || !*user)
295 user = "nobody";
296
297 if (!(pass = getpassf(password_file))
298 && !(pass = getenv("RSYNC_PASSWORD"))) {
299 /* XXX: cyeoh says that getpass is deprecated, because
300 * it may return a truncated password on some systems,
301 * and it is not in the LSB.
302 *
303 * Andrew Klein says that getpassphrase() is present
304 * on Solaris and reads up to 256 characters.
305 *
306 * OpenBSD has a readpassphrase() that might be more suitable.
307 */
308 pass = getpass("Password: ");
309 }
310
311 /* Any errors output during password handling aren't transfer errors. */
312 log_got_error = 0;
313
314 if (!pass)
315 pass = "";
316
317 generate_hash(pass, challenge, pass2);
318 io_printf(fd, "%s %s\n", user, pass2);
319}