1: /*
2: * Routines to authenticate access to a daemon (hosts allow/deny).
3: *
4: * Copyright (C) 1998 Andrew Tridgell
5: * Copyright (C) 2004-2020 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 "ifuncs.h"
23:
24: static int allow_forward_dns;
25:
26: extern const char undetermined_hostname[];
27:
28: static int match_hostname(const char **host_ptr, const char *addr, const char *tok)
29: {
30: struct hostent *hp;
31: unsigned int i;
32: const char *host = *host_ptr;
33:
34: if (!host || !*host)
35: return 0;
36:
37: #ifdef HAVE_INNETGR
38: if (*tok == '@' && tok[1])
39: return innetgr(tok + 1, host, NULL, NULL);
40: #endif
41:
42: /* First check if the reverse-DNS-determined hostname matches. */
43: if (iwildmatch(tok, host))
44: return 1;
45:
46: if (!allow_forward_dns)
47: return 0;
48:
49: /* Fail quietly if tok is an address or wildcarded entry, not a simple hostname. */
50: if (!tok[strspn(tok, ".0123456789")] || tok[strcspn(tok, ":/*?[")])
51: return 0;
52:
53: /* Now try forward-DNS on the token (config-specified hostname) and see if the IP matches. */
54: if (!(hp = gethostbyname(tok)))
55: return 0;
56:
57: for (i = 0; hp->h_addr_list[i] != NULL; i++) {
58: if (strcmp(addr, inet_ntoa(*(struct in_addr*)(hp->h_addr_list[i]))) == 0) {
59: /* If reverse lookups are off, we'll use the conf-specified
60: * hostname in preference to UNDETERMINED. */
61: if (host == undetermined_hostname)
62: *host_ptr = strdup(tok);
63: return 1;
64: }
65: }
66:
67: return 0;
68: }
69:
70: static int match_binary(const char *b1, const char *b2, const char *mask, int addrlen)
71: {
72: int i;
73:
74: for (i = 0; i < addrlen; i++) {
75: if ((b1[i] ^ b2[i]) & mask[i])
76: return 0;
77: }
78:
79: return 1;
80: }
81:
82: static void make_mask(char *mask, int plen, int addrlen)
83: {
84: int w, b;
85:
86: w = plen >> 3;
87: b = plen & 0x7;
88:
89: if (w)
90: memset(mask, 0xff, w);
91: if (w < addrlen)
92: mask[w] = 0xff & (0xff<<(8-b));
93: if (w+1 < addrlen)
94: memset(mask+w+1, 0, addrlen-w-1);
95:
96: return;
97: }
98:
99: static int match_address(const char *addr, const char *tok)
100: {
101: char *p;
102: struct addrinfo hints, *resa, *rest;
103: int gai;
104: int ret = 0;
105: int addrlen = 0;
106: #ifdef HAVE_STRTOL
107: long int bits;
108: #else
109: int bits;
110: #endif
111: char mask[16];
112: char *a = NULL, *t = NULL;
113:
114: if (!addr || !*addr)
115: return 0;
116:
117: p = strchr(tok,'/');
118: if (p)
119: *p = '\0';
120:
121: /* Fail quietly if tok is a hostname, not an address. */
122: if (tok[strspn(tok, ".0123456789")] && strchr(tok, ':') == NULL) {
123: if (p)
124: *p = '/';
125: return 0;
126: }
127:
128: memset(&hints, 0, sizeof(hints));
129: hints.ai_family = PF_UNSPEC;
130: hints.ai_socktype = SOCK_STREAM;
131: #ifdef AI_NUMERICHOST
132: hints.ai_flags = AI_NUMERICHOST;
133: #endif
134:
135: if (getaddrinfo(addr, NULL, &hints, &resa) != 0) {
136: if (p)
137: *p = '/';
138: return 0;
139: }
140:
141: gai = getaddrinfo(tok, NULL, &hints, &rest);
142: if (p)
143: *p++ = '/';
144: if (gai != 0) {
145: rprintf(FLOG, "error matching address %s: %s\n",
146: tok, gai_strerror(gai));
147: freeaddrinfo(resa);
148: return 0;
149: }
150:
151: if (rest->ai_family != resa->ai_family) {
152: ret = 0;
153: goto out;
154: }
155:
156: switch(resa->ai_family) {
157: case PF_INET:
158: a = (char *)&((struct sockaddr_in *)resa->ai_addr)->sin_addr;
159: t = (char *)&((struct sockaddr_in *)rest->ai_addr)->sin_addr;
160: addrlen = 4;
161:
162: break;
163:
164: #ifdef INET6
165: case PF_INET6: {
166: struct sockaddr_in6 *sin6a, *sin6t;
167:
168: sin6a = (struct sockaddr_in6 *)resa->ai_addr;
169: sin6t = (struct sockaddr_in6 *)rest->ai_addr;
170:
171: a = (char *)&sin6a->sin6_addr;
172: t = (char *)&sin6t->sin6_addr;
173:
174: addrlen = 16;
175:
176: #ifdef HAVE_SOCKADDR_IN6_SCOPE_ID
177: if (sin6t->sin6_scope_id && sin6a->sin6_scope_id != sin6t->sin6_scope_id) {
178: ret = 0;
179: goto out;
180: }
181: #endif
182:
183: break;
184: }
185: #endif
186: default:
187: rprintf(FLOG, "unknown family %u\n", rest->ai_family);
188: ret = 0;
189: goto out;
190: }
191:
192: bits = -1;
193: if (p) {
194: if (inet_pton(resa->ai_addr->sa_family, p, mask) <= 0) {
195: #ifdef HAVE_STRTOL
196: char *ep = NULL;
197: #else
198: unsigned char *pp;
199: #endif
200:
201: #ifdef HAVE_STRTOL
202: bits = strtol(p, &ep, 10);
203: if (!*p || *ep) {
204: rprintf(FLOG, "malformed mask in %s\n", tok);
205: ret = 0;
206: goto out;
207: }
208: #else
209: for (pp = (unsigned char *)p; *pp; pp++) {
210: if (!isascii(*pp) || !isdigit(*pp)) {
211: rprintf(FLOG, "malformed mask in %s\n", tok);
212: ret = 0;
213: goto out;
214: }
215: }
216: bits = atoi(p);
217: #endif
218: if (bits == 0) {
219: ret = 1;
220: goto out;
221: }
222: if (bits < 0 || bits > (addrlen << 3)) {
223: rprintf(FLOG, "malformed mask in %s\n", tok);
224: ret = 0;
225: goto out;
226: }
227: }
228: } else {
229: bits = 128;
230: }
231:
232: if (bits >= 0)
233: make_mask(mask, bits, addrlen);
234:
235: ret = match_binary(a, t, mask, addrlen);
236:
237: out:
238: freeaddrinfo(resa);
239: freeaddrinfo(rest);
240: return ret;
241: }
242:
243: static int access_match(const char *list, const char *addr, const char **host_ptr)
244: {
245: char *tok;
246: char *list2 = strdup(list);
247:
248: strlower(list2);
249:
250: for (tok = strtok(list2, " ,\t"); tok; tok = strtok(NULL, " ,\t")) {
251: if (match_hostname(host_ptr, addr, tok) || match_address(addr, tok)) {
252: free(list2);
253: return 1;
254: }
255: }
256:
257: free(list2);
258: return 0;
259: }
260:
261: int allow_access(const char *addr, const char **host_ptr, int i)
262: {
263: const char *allow_list = lp_hosts_allow(i);
264: const char *deny_list = lp_hosts_deny(i);
265:
266: if (allow_list && !*allow_list)
267: allow_list = NULL;
268: if (deny_list && !*deny_list)
269: deny_list = NULL;
270:
271: allow_forward_dns = lp_forward_lookup(i);
272:
273: /* If we match an allow-list item, we always allow access. */
274: if (allow_list) {
275: if (access_match(allow_list, addr, host_ptr))
276: return 1;
277: /* For an allow-list w/o a deny-list, disallow non-matches. */
278: if (!deny_list)
279: return 0;
280: }
281:
282: /* If we match a deny-list item (and got past any allow-list
283: * items), we always disallow access. */
284: if (deny_list && access_match(deny_list, addr, host_ptr))
285: return 0;
286:
287: /* Allow all other access. */
288: return 1;
289: }
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