1: /*
2: * Support rsync daemon authentication.
3: *
4: * Copyright (C) 1998-2000 Andrew Tridgell
5: * Copyright (C) 2002-2020 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: #include "ifuncs.h"
24:
25: extern int read_only;
26: extern char *password_file;
27:
28: /***************************************************************************
29: encode a buffer using base64 - simple and slow algorithm. null terminates
30: the result.
31: ***************************************************************************/
32: void base64_encode(const char *buf, int len, char *out, int pad)
33: {
34: char *b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
35: int bit_offset, byte_offset, idx, i;
36: const uchar *d = (const uchar *)buf;
37: int bytes = (len*8 + 5)/6;
38:
39: for (i = 0; i < bytes; i++) {
40: byte_offset = (i*6)/8;
41: bit_offset = (i*6)%8;
42: if (bit_offset < 3) {
43: idx = (d[byte_offset] >> (2-bit_offset)) & 0x3F;
44: } else {
45: idx = (d[byte_offset] << (bit_offset-2)) & 0x3F;
46: if (byte_offset+1 < len) {
47: idx |= (d[byte_offset+1] >> (8-(bit_offset-2)));
48: }
49: }
50: out[i] = b64[idx];
51: }
52:
53: while (pad && (i % 4))
54: out[i++] = '=';
55:
56: out[i] = '\0';
57: }
58:
59: /* Generate a challenge buffer and return it base64-encoded. */
60: static void gen_challenge(const char *addr, char *challenge)
61: {
62: char input[32];
63: char digest[MAX_DIGEST_LEN];
64: struct timeval tv;
65: int len;
66:
67: memset(input, 0, sizeof input);
68:
69: strlcpy(input, addr, 17);
70: sys_gettimeofday(&tv);
71: SIVAL(input, 16, tv.tv_sec);
72: SIVAL(input, 20, tv.tv_usec);
73: SIVAL(input, 24, getpid());
74:
75: sum_init(-1, 0);
76: sum_update(input, sizeof input);
77: len = sum_end(digest);
78:
79: base64_encode(digest, len, challenge, 0);
80: }
81:
82: /* Generate an MD4 hash created from the combination of the password
83: * and the challenge string and return it base64-encoded. */
84: static void generate_hash(const char *in, const char *challenge, char *out)
85: {
86: char buf[MAX_DIGEST_LEN];
87: int len;
88:
89: sum_init(-1, 0);
90: sum_update(in, strlen(in));
91: sum_update(challenge, strlen(challenge));
92: len = sum_end(buf);
93:
94: base64_encode(buf, len, out, 0);
95: }
96:
97: /* Return the secret for a user from the secret file, null terminated.
98: * Maximum length is len (not counting the null). */
99: static const char *check_secret(int module, const char *user, const char *group,
100: const char *challenge, const char *pass)
101: {
102: char line[1024];
103: char pass2[MAX_DIGEST_LEN*2];
104: const char *fname = lp_secrets_file(module);
105: STRUCT_STAT st;
106: int ok = 1;
107: int user_len = strlen(user);
108: int group_len = group ? strlen(group) : 0;
109: char *err;
110: FILE *fh;
111:
112: if (!fname || !*fname || (fh = fopen(fname, "r")) == NULL)
113: return "no secrets file";
114:
115: if (do_fstat(fileno(fh), &st) == -1) {
116: rsyserr(FLOG, errno, "fstat(%s)", fname);
117: ok = 0;
118: } else if (lp_strict_modes(module)) {
119: if ((st.st_mode & 06) != 0) {
120: rprintf(FLOG, "secrets file must not be other-accessible (see strict modes option)\n");
121: ok = 0;
122: } else if (MY_UID() == ROOT_UID && st.st_uid != ROOT_UID) {
123: rprintf(FLOG, "secrets file must be owned by root when running as root (see strict modes)\n");
124: ok = 0;
125: }
126: }
127: if (!ok) {
128: fclose(fh);
129: return "ignoring secrets file";
130: }
131:
132: if (*user == '#') {
133: /* Reject attempt to match a comment. */
134: fclose(fh);
135: return "invalid username";
136: }
137:
138: /* Try to find a line that starts with the user (or @group) name and a ':'. */
139: err = "secret not found";
140: while ((user || group) && fgets(line, sizeof line, fh) != NULL) {
141: const char **ptr, *s = strtok(line, "\n\r");
142: int len;
143: if (!s)
144: continue;
145: if (*s == '@') {
146: ptr = &group;
147: len = group_len;
148: s++;
149: } else {
150: ptr = &user;
151: len = user_len;
152: }
153: if (!*ptr || strncmp(s, *ptr, len) != 0 || s[len] != ':')
154: continue;
155: generate_hash(s+len+1, challenge, pass2);
156: if (strcmp(pass, pass2) == 0) {
157: err = NULL;
158: break;
159: }
160: err = "password mismatch";
161: *ptr = NULL; /* Don't look for name again. */
162: }
163:
164: fclose(fh);
165:
166: force_memzero(line, sizeof line);
167: force_memzero(pass2, sizeof pass2);
168:
169: return err;
170: }
171:
172: static const char *getpassf(const char *filename)
173: {
174: STRUCT_STAT st;
175: char buffer[512], *p;
176: int n;
177:
178: if (!filename)
179: return NULL;
180:
181: if (strcmp(filename, "-") == 0) {
182: n = fgets(buffer, sizeof buffer, stdin) == NULL ? -1 : (int)strlen(buffer);
183: } else {
184: int fd;
185:
186: if ((fd = open(filename,O_RDONLY)) < 0) {
187: rsyserr(FERROR, errno, "could not open password file %s", filename);
188: exit_cleanup(RERR_SYNTAX);
189: }
190:
191: if (do_stat(filename, &st) == -1) {
192: rsyserr(FERROR, errno, "stat(%s)", filename);
193: exit_cleanup(RERR_SYNTAX);
194: }
195: if ((st.st_mode & 06) != 0) {
196: rprintf(FERROR, "ERROR: password file must not be other-accessible\n");
197: exit_cleanup(RERR_SYNTAX);
198: }
199: if (MY_UID() == ROOT_UID && st.st_uid != ROOT_UID) {
200: rprintf(FERROR, "ERROR: password file must be owned by root when running as root\n");
201: exit_cleanup(RERR_SYNTAX);
202: }
203:
204: n = read(fd, buffer, sizeof buffer - 1);
205: close(fd);
206: }
207:
208: if (n > 0) {
209: buffer[n] = '\0';
210: if ((p = strtok(buffer, "\n\r")) != NULL)
211: return strdup(p);
212: }
213:
214: rprintf(FERROR, "ERROR: failed to read a password from %s\n", filename);
215: exit_cleanup(RERR_SYNTAX);
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: */
224: char *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: const char **auth_uid_groups = NULL;
231: int auth_uid_groups_cnt = -1;
232: const char *err = NULL;
233: int group_match = -1;
234: char *tok, *pass;
235: char opt_ch = '\0';
236:
237: /* if no auth list then allow anyone in! */
238: if (!users || !*users)
239: return "";
240:
241: gen_challenge(addr, challenge);
242:
243: io_printf(f_out, "%s%s\n", leader, challenge);
244:
245: if (!read_line_old(f_in, line, sizeof line, 0)
246: || (pass = strchr(line, ' ')) == NULL) {
247: rprintf(FLOG, "auth failed on module %s from %s (%s): "
248: "invalid challenge response\n",
249: lp_name(module), host, addr);
250: return NULL;
251: }
252: *pass++ = '\0';
253:
254: users = strdup(users);
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: auth_uid_groups = new_array(const char *, auth_uid_groups_cnt);
291: for (j = 0; j < auth_uid_groups_cnt; j++)
292: auth_uid_groups[j] = gid_to_group(gid_array[j]);
293: }
294: }
295: for (j = 0; j < auth_uid_groups_cnt; j++) {
296: if (auth_uid_groups[j] && wildmatch(tok+1, auth_uid_groups[j])) {
297: group_match = j;
298: break;
299: }
300: }
301: if (group_match >= 0)
302: break;
303: #else
304: rprintf(FLOG, "your computer doesn't support getgrouplist(), so no @group authorization is possible.\n");
305: #endif
306: }
307: }
308:
309: free(users);
310:
311: if (!tok)
312: err = "no matching rule";
313: else if (opt_ch == 'd')
314: err = "denied by rule";
315: else {
316: const char *group = group_match >= 0 ? auth_uid_groups[group_match] : NULL;
317: err = check_secret(module, line, group, challenge, pass);
318: }
319:
320: force_memzero(challenge, sizeof challenge);
321: force_memzero(pass, strlen(pass));
322:
323: if (auth_uid_groups) {
324: int j;
325: for (j = 0; j < auth_uid_groups_cnt; j++) {
326: if (auth_uid_groups[j])
327: free((char*)auth_uid_groups[j]);
328: }
329: free(auth_uid_groups);
330: }
331:
332: if (err) {
333: rprintf(FLOG, "auth failed on module %s from %s (%s) for %s: %s\n",
334: lp_name(module), host, addr, line, err);
335: return NULL;
336: }
337:
338: if (opt_ch == 'r')
339: read_only = 1;
340: else if (opt_ch == 'w')
341: read_only = 0;
342:
343: return strdup(line);
344: }
345:
346: void auth_client(int fd, const char *user, const char *challenge)
347: {
348: const char *pass;
349: char pass2[MAX_DIGEST_LEN*2];
350:
351: if (!user || !*user)
352: user = "nobody";
353:
354: if (!(pass = getpassf(password_file))
355: && !(pass = getenv("RSYNC_PASSWORD"))) {
356: /* XXX: cyeoh says that getpass is deprecated, because
357: * it may return a truncated password on some systems,
358: * and it is not in the LSB.
359: *
360: * Andrew Klein says that getpassphrase() is present
361: * on Solaris and reads up to 256 characters.
362: *
363: * OpenBSD has a readpassphrase() that might be more suitable.
364: */
365: pass = getpass("Password: ");
366: }
367:
368: if (!pass)
369: pass = "";
370:
371: generate_hash(pass, challenge, pass2);
372: io_printf(fd, "%s %s\n", user, pass2);
373: }
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