1: /*
2: * Support rsync daemon authentication.
3: *
4: * Copyright (C) 1998-2000 Andrew Tridgell
5: * Copyright (C) 2002-2015 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: #include "itypes.h"
23:
24: extern int read_only;
25: extern char *password_file;
26:
27: /***************************************************************************
28: encode a buffer using base64 - simple and slow algorithm. null terminates
29: the result.
30: ***************************************************************************/
31: void base64_encode(const char *buf, int len, char *out, int pad)
32: {
33: char *b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
34: int bit_offset, byte_offset, idx, i;
35: const uchar *d = (const uchar *)buf;
36: int bytes = (len*8 + 5)/6;
37:
38: for (i = 0; i < bytes; i++) {
39: byte_offset = (i*6)/8;
40: bit_offset = (i*6)%8;
41: if (bit_offset < 3) {
42: idx = (d[byte_offset] >> (2-bit_offset)) & 0x3F;
43: } else {
44: idx = (d[byte_offset] << (bit_offset-2)) & 0x3F;
45: if (byte_offset+1 < len) {
46: idx |= (d[byte_offset+1] >> (8-(bit_offset-2)));
47: }
48: }
49: out[i] = b64[idx];
50: }
51:
52: while (pad && (i % 4))
53: out[i++] = '=';
54:
55: out[i] = '\0';
56: }
57:
58: /* Generate a challenge buffer and return it base64-encoded. */
59: static void gen_challenge(const char *addr, char *challenge)
60: {
61: char input[32];
62: char digest[MAX_DIGEST_LEN];
63: struct timeval tv;
64: int len;
65:
66: memset(input, 0, sizeof input);
67:
68: strlcpy(input, addr, 17);
69: sys_gettimeofday(&tv);
70: SIVAL(input, 16, tv.tv_sec);
71: SIVAL(input, 20, tv.tv_usec);
72: SIVAL(input, 24, getpid());
73:
74: sum_init(0);
75: sum_update(input, sizeof input);
76: len = sum_end(digest);
77:
78: base64_encode(digest, len, challenge, 0);
79: }
80:
81: /* Generate an MD4 hash created from the combination of the password
82: * and the challenge string and return it base64-encoded. */
83: static void generate_hash(const char *in, const char *challenge, char *out)
84: {
85: char buf[MAX_DIGEST_LEN];
86: int len;
87:
88: sum_init(0);
89: sum_update(in, strlen(in));
90: sum_update(challenge, strlen(challenge));
91: len = sum_end(buf);
92:
93: base64_encode(buf, len, out, 0);
94: }
95:
96: /* Return the secret for a user from the secret file, null terminated.
97: * Maximum length is len (not counting the null). */
98: static const char *check_secret(int module, const char *user, const char *group,
99: const char *challenge, const char *pass)
100: {
101: char line[1024];
102: char pass2[MAX_DIGEST_LEN*2];
103: const char *fname = lp_secrets_file(module);
104: STRUCT_STAT st;
105: int ok = 1;
106: int user_len = strlen(user);
107: int group_len = group ? strlen(group) : 0;
108: char *err;
109: FILE *fh;
110:
111: if (!fname || !*fname || (fh = fopen(fname, "r")) == NULL)
112: return "no secrets file";
113:
114: if (do_fstat(fileno(fh), &st) == -1) {
115: rsyserr(FLOG, errno, "fstat(%s)", fname);
116: ok = 0;
117: } else if (lp_strict_modes(module)) {
118: if ((st.st_mode & 06) != 0) {
119: rprintf(FLOG, "secrets file must not be other-accessible (see strict modes option)\n");
120: ok = 0;
121: } else if (MY_UID() == 0 && st.st_uid != 0) {
122: rprintf(FLOG, "secrets file must be owned by root when running as root (see strict modes)\n");
123: ok = 0;
124: }
125: }
126: if (!ok) {
127: fclose(fh);
128: return "ignoring secrets file";
129: }
130:
131: if (*user == '#') {
132: /* Reject attempt to match a comment. */
133: fclose(fh);
134: return "invalid username";
135: }
136:
137: /* Try to find a line that starts with the user (or @group) name and a ':'. */
138: err = "secret not found";
139: while ((user || group) && fgets(line, sizeof line, fh) != NULL) {
140: const char **ptr, *s = strtok(line, "\n\r");
141: int len;
142: if (!s)
143: continue;
144: if (*s == '@') {
145: ptr = &group;
146: len = group_len;
147: s++;
148: } else {
149: ptr = &user;
150: len = user_len;
151: }
152: if (!*ptr || strncmp(s, *ptr, len) != 0 || s[len] != ':')
153: continue;
154: generate_hash(s+len+1, challenge, pass2);
155: if (strcmp(pass, pass2) == 0) {
156: err = NULL;
157: break;
158: }
159: err = "password mismatch";
160: *ptr = NULL; /* Don't look for name again. */
161: }
162:
163: fclose(fh);
164:
165: memset(line, 0, sizeof line);
166: memset(pass2, 0, sizeof pass2);
167:
168: return err;
169: }
170:
171: static const char *getpassf(const char *filename)
172: {
173: STRUCT_STAT st;
174: char buffer[512], *p;
175: int n;
176:
177: if (!filename)
178: return NULL;
179:
180: if (strcmp(filename, "-") == 0) {
181: n = fgets(buffer, sizeof buffer, stdin) == NULL ? -1 : (int)strlen(buffer);
182: } else {
183: int fd;
184:
185: if ((fd = open(filename,O_RDONLY)) < 0) {
186: rsyserr(FERROR, errno, "could not open password file %s", filename);
187: exit_cleanup(RERR_SYNTAX);
188: }
189:
190: if (do_stat(filename, &st) == -1) {
191: rsyserr(FERROR, errno, "stat(%s)", filename);
192: exit_cleanup(RERR_SYNTAX);
193: }
194: if ((st.st_mode & 06) != 0) {
195: rprintf(FERROR, "ERROR: password file must not be other-accessible\n");
196: exit_cleanup(RERR_SYNTAX);
197: }
198: if (MY_UID() == 0 && st.st_uid != 0) {
199: rprintf(FERROR, "ERROR: password file must be owned by root when running as root\n");
200: exit_cleanup(RERR_SYNTAX);
201: }
202:
203: n = read(fd, buffer, sizeof buffer - 1);
204: close(fd);
205: }
206:
207: if (n > 0) {
208: buffer[n] = '\0';
209: if ((p = strtok(buffer, "\n\r")) != NULL)
210: return strdup(p);
211: }
212:
213: rprintf(FERROR, "ERROR: failed to read a password from %s\n", filename);
214: exit_cleanup(RERR_SYNTAX);
215: }
216:
217: /* Possibly negotiate authentication with the client. Use "leader" to
218: * start off the auth if necessary.
219: *
220: * Return NULL if authentication failed. Return "" if anonymous access.
221: * Otherwise return username.
222: */
223: char *auth_server(int f_in, int f_out, int module, const char *host,
224: const char *addr, const char *leader)
225: {
226: char *users = lp_auth_users(module);
227: char challenge[MAX_DIGEST_LEN*2];
228: char line[BIGPATHBUFLEN];
229: char **auth_uid_groups = NULL;
230: int auth_uid_groups_cnt = -1;
231: const char *err = NULL;
232: int group_match = -1;
233: char *tok, *pass;
234: char opt_ch = '\0';
235:
236: /* if no auth list then allow anyone in! */
237: if (!users || !*users)
238: return "";
239:
240: gen_challenge(addr, challenge);
241:
242: io_printf(f_out, "%s%s\n", leader, challenge);
243:
244: if (!read_line_old(f_in, line, sizeof line, 0)
245: || (pass = strchr(line, ' ')) == NULL) {
246: rprintf(FLOG, "auth failed on module %s from %s (%s): "
247: "invalid challenge response\n",
248: lp_name(module), host, addr);
249: return NULL;
250: }
251: *pass++ = '\0';
252:
253: if (!(users = strdup(users)))
254: out_of_memory("auth_server");
255:
256: for (tok = strtok(users, " ,\t"); tok; tok = strtok(NULL, " ,\t")) {
257: char *opts;
258: /* See if the user appended :deny, :ro, or :rw. */
259: if ((opts = strchr(tok, ':')) != NULL) {
260: *opts++ = '\0';
261: opt_ch = isUpper(opts) ? toLower(opts) : *opts;
262: if (opt_ch == 'r') { /* handle ro and rw */
263: opt_ch = isUpper(opts+1) ? toLower(opts+1) : opts[1];
264: if (opt_ch == 'o')
265: opt_ch = 'r';
266: else if (opt_ch != 'w')
267: opt_ch = '\0';
268: } else if (opt_ch != 'd') /* if it's not deny, ignore it */
269: opt_ch = '\0';
270: } else
271: opt_ch = '\0';
272: if (*tok != '@') {
273: /* Match the username */
274: if (wildmatch(tok, line))
275: break;
276: } else {
277: #ifdef HAVE_GETGROUPLIST
278: int j;
279: /* See if authorizing user is a real user, and if so, see
280: * if it is in a group that matches tok+1 wildmat. */
281: if (auth_uid_groups_cnt < 0) {
282: item_list gid_list = EMPTY_ITEM_LIST;
283: uid_t auth_uid;
284: if (!user_to_uid(line, &auth_uid, False)
285: || getallgroups(auth_uid, &gid_list) != NULL)
286: auth_uid_groups_cnt = 0;
287: else {
288: gid_t *gid_array = gid_list.items;
289: auth_uid_groups_cnt = gid_list.count;
290: if ((auth_uid_groups = new_array(char *, auth_uid_groups_cnt)) == NULL)
291: out_of_memory("auth_server");
292: for (j = 0; j < auth_uid_groups_cnt; j++)
293: auth_uid_groups[j] = gid_to_group(gid_array[j]);
294: }
295: }
296: for (j = 0; j < auth_uid_groups_cnt; j++) {
297: if (auth_uid_groups[j] && wildmatch(tok+1, auth_uid_groups[j])) {
298: group_match = j;
299: break;
300: }
301: }
302: if (group_match >= 0)
303: break;
304: #else
305: rprintf(FLOG, "your computer doesn't support getgrouplist(), so no @group authorization is possible.\n");
306: #endif
307: }
308: }
309:
310: free(users);
311:
312: if (!tok)
313: err = "no matching rule";
314: else if (opt_ch == 'd')
315: err = "denied by rule";
316: else {
317: char *group = group_match >= 0 ? auth_uid_groups[group_match] : NULL;
318: err = check_secret(module, line, group, challenge, pass);
319: }
320:
321: memset(challenge, 0, sizeof challenge);
322: memset(pass, 0, strlen(pass));
323:
324: if (auth_uid_groups) {
325: int j;
326: for (j = 0; j < auth_uid_groups_cnt; j++) {
327: if (auth_uid_groups[j])
328: free(auth_uid_groups[j]);
329: }
330: free(auth_uid_groups);
331: }
332:
333: if (err) {
334: rprintf(FLOG, "auth failed on module %s from %s (%s) for %s: %s\n",
335: lp_name(module), host, addr, line, err);
336: return NULL;
337: }
338:
339: if (opt_ch == 'r')
340: read_only = 1;
341: else if (opt_ch == 'w')
342: read_only = 0;
343:
344: return strdup(line);
345: }
346:
347: void auth_client(int fd, const char *user, const char *challenge)
348: {
349: const char *pass;
350: char pass2[MAX_DIGEST_LEN*2];
351:
352: if (!user || !*user)
353: user = "nobody";
354:
355: if (!(pass = getpassf(password_file))
356: && !(pass = getenv("RSYNC_PASSWORD"))) {
357: /* XXX: cyeoh says that getpass is deprecated, because
358: * it may return a truncated password on some systems,
359: * and it is not in the LSB.
360: *
361: * Andrew Klein says that getpassphrase() is present
362: * on Solaris and reads up to 256 characters.
363: *
364: * OpenBSD has a readpassphrase() that might be more suitable.
365: */
366: pass = getpass("Password: ");
367: }
368:
369: if (!pass)
370: pass = "";
371:
372: generate_hash(pass, challenge, pass2);
373: io_printf(fd, "%s %s\n", user, pass2);
374: }
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