1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
23  * Use is subject to license terms.
24  */
25 
26 /*
27  * All routines necessary to deal the "netmasks" database.  The sources
28  * contain mappings between 32 bit Internet addresses and corresponding
29  * 32 bit Internet address masks. The addresses are in dotted internet
30  * address notation.
31  */
32 
33 #include <stdio.h>
34 #include <ctype.h>
35 #include <string.h>
36 #include <stdlib.h>
37 #include <sys/types.h>
38 #include <sys/socket.h>
39 #include <net/if.h>
40 #include <netinet/in.h>
41 #include <arpa/inet.h>
42 #include <nss_dbdefs.h>
43 
44 int str2addr(const char *, int, void *, char *, int);
45 
46 static DEFINE_NSS_DB_ROOT(db_root);
47 
48 void
_nss_initf_netmasks(nss_db_params_t * p)49 _nss_initf_netmasks(nss_db_params_t *p)
50 {
51 	p->name = NSS_DBNAM_NETMASKS;
52 	p->default_config = NSS_DEFCONF_NETMASKS;
53 }
54 
55 /*
56  * Print a network number such as 129.144 as well as an IP address.
57  * Assumes network byte order for both IP addresses and network numbers
58  * (Network numbers are normally passed around in host byte order).
59  * to be MT safe, use a passed in buffer like otherget*_r APIs.
60  */
61 static char *
inet_nettoa(struct in_addr in,char * result,int len)62 inet_nettoa(struct in_addr in, char *result, int len)
63 {
64 	uint32_t addr = in.s_addr;
65 	uchar_t *up = (uchar_t *)&addr;
66 
67 	if (result == NULL)
68 		return (NULL);
69 
70 	/* Omit leading zeros */
71 	if (up[0]) {
72 		(void) snprintf(result, len, "%d.%d.%d.%d",
73 		    up[0], up[1], up[2], up[3]);
74 	} else if (up[1]) {
75 		(void) snprintf(result, len, "%d.%d.%d", up[1], up[2], up[3]);
76 	} else if (up[2]) {
77 		(void) snprintf(result, len, "%d.%d", up[2], up[3]);
78 	} else {
79 		(void) snprintf(result, len, "%d", up[3]);
80 	}
81 	return (result);
82 }
83 
84 /*
85  * Given a 32 bit key look it up in the netmasks database
86  * based on the "netmasks" policy in /etc/nsswitch.conf.
87  * If the key is a network number with the trailing zero's removed
88  * (e.g. "192.9.200") this routine can't use inet_ntoa to convert
89  * the address to the string key.
90  * Returns zero if successful, non-zero otherwise.
91  */
92 static int
getnetmaskbykey(const struct in_addr addr,struct in_addr * mask)93 getnetmaskbykey(const struct in_addr addr, struct in_addr *mask)
94 {
95 	nss_XbyY_args_t arg;
96 	nss_status_t	res;
97 	char		tmp[NSS_LINELEN_NETMASKS];
98 
99 	/*
100 	 * let the backend do the allocation to store stuff for parsing.
101 	 * To simplify things, we put the dotted internet address form of
102 	 * the network address in the 'name' field as a filter to speed
103 	 * up the lookup.
104 	 */
105 	if (inet_nettoa(addr, tmp, NSS_LINELEN_NETMASKS) == NULL)
106 		return (NSS_NOTFOUND);
107 
108 	NSS_XbyY_INIT(&arg, mask, NULL, 0, str2addr);
109 	arg.key.name = tmp;
110 	res = nss_search(&db_root, _nss_initf_netmasks,
111 			NSS_DBOP_NETMASKS_BYNET, &arg);
112 	(void) NSS_XbyY_FINI(&arg);
113 	return (arg.status = res);
114 }
115 
116 /*
117  * Given a 32 bit internet network number, it finds the corresponding netmask
118  * address based on the "netmasks" policy in /etc/nsswitch.conf.
119  * Returns zero if successful, non-zero otherwise.
120  * Check both for the (masked) network number and the shifted network
121  * number (e.g., both "10.0.0.0" and "10").
122  * Assumes that the caller passes in an unshifted number (or an IP address).
123  */
124 int
getnetmaskbynet(const struct in_addr net,struct in_addr * mask)125 getnetmaskbynet(const struct in_addr net, struct in_addr *mask)
126 {
127 	struct in_addr net1, net2;
128 	uint32_t i;
129 
130 	i = ntohl(net.s_addr);
131 
132 	/*
133 	 * Try looking for the network number both with and without
134 	 * the trailing zeros.
135 	 */
136 	if ((i & IN_CLASSA_NET) == 0) {
137 		/* Assume already a right-shifted network number */
138 		net2.s_addr = htonl(i);
139 		if ((i & IN_CLASSB_NET) != 0) {
140 			net1.s_addr = htonl(i << IN_CLASSC_NSHIFT);
141 		} else if ((i & IN_CLASSC_NET) != 0) {
142 			net1.s_addr = htonl(i << IN_CLASSB_NSHIFT);
143 		} else {
144 			net1.s_addr = htonl(i << IN_CLASSA_NSHIFT);
145 		}
146 	} else if (IN_CLASSA(i)) {
147 		net1.s_addr = htonl(i & IN_CLASSA_NET);
148 		net2.s_addr = htonl(i >> IN_CLASSA_NSHIFT);
149 	} else if (IN_CLASSB(i)) {
150 		net1.s_addr = htonl(i & IN_CLASSB_NET);
151 		net2.s_addr = htonl(i >> IN_CLASSB_NSHIFT);
152 	} else {
153 		net1.s_addr = htonl(i & IN_CLASSC_NET);
154 		net2.s_addr = htonl(i >> IN_CLASSC_NSHIFT);
155 	}
156 
157 	if (getnetmaskbykey(net1, mask) == 0) {
158 		return (0);
159 	}
160 	if (getnetmaskbykey(net2, mask) == 0) {
161 		return (0);
162 	}
163 	return (-1);
164 }
165 
166 /*
167  * Find the netmask used for an IP address.
168  * Returns zero if successful, non-zero otherwise.
169  *
170  * Support Variable Length Subnetmasks by looking for the longest
171  * matching subnetmask in the database.
172  * Start by looking for a match for the full IP address and
173  * mask off one rightmost bit after another until we find a match.
174  * Note that for a match the found netmask must match what was used
175  * for the lookup masking.
176  * As a fallback for compatibility finally lookup the network
177  * number with and without the trailing zeros.
178  * In order to suppress redundant lookups in the name service
179  * we keep the previous lookup key and compare against it before
180  * doing the lookup.
181  */
182 int
getnetmaskbyaddr(const struct in_addr addr,struct in_addr * mask)183 getnetmaskbyaddr(const struct in_addr addr, struct in_addr *mask)
184 {
185 	struct in_addr prevnet, net;
186 	uint32_t i, maskoff;
187 
188 	i = ntohl(addr.s_addr);
189 	prevnet.s_addr = 0;
190 	mask->s_addr = 0;
191 
192 	for (maskoff = 0xFFFFFFFF; maskoff != 0; maskoff = maskoff << 1) {
193 		net.s_addr = htonl(i & maskoff);
194 
195 		if (net.s_addr != prevnet.s_addr) {
196 			if (getnetmaskbykey(net, mask) != 0) {
197 				mask->s_addr = 0;
198 			}
199 		}
200 		if (htonl(maskoff) == mask->s_addr)
201 			return (0);
202 
203 		prevnet.s_addr = net.s_addr;
204 	}
205 
206 	/*
207 	 * Non-VLSM fallback.
208 	 * Try looking for the network number with and without the trailing
209 	 * zeros.
210 	 */
211 	return (getnetmaskbynet(addr, mask));
212 }
213 
214 /*
215  * Parse netmasks entry into its components. The network address is placed
216  * in buffer for use by check_addr for 'files' backend, to match the network
217  * address. The network address is placed in the buffer as a network order
218  * internet address, if buffer is non null. The network order form of the mask
219  * itself is placed in 'ent'.
220  */
221 int
str2addr(const char * instr,int lenstr,void * ent,char * buffer,int buflen)222 str2addr(const char *instr, int lenstr, void *ent, char *buffer, int buflen)
223 {
224 	int	retval;
225 	struct in_addr	*mask = (struct in_addr *)ent;
226 	const char	*p, *limit, *start;
227 	struct in_addr	addr;
228 	int		i;
229 	char		tmp[NSS_LINELEN_NETMASKS];
230 
231 	p = instr;
232 	limit = p + lenstr;
233 	retval = NSS_STR_PARSE_PARSE;
234 
235 	while (p < limit && isspace(*p))	/* skip leading whitespace */
236 		p++;
237 
238 	if (buffer) {	/* for 'files' backend verification */
239 		for (start = p, i = 0; p < limit && !isspace(*p); p++)
240 			i++;
241 		if (p < limit && i < buflen) {
242 			(void) memcpy(tmp, start, i);
243 			tmp[i] = '\0';
244 			addr.s_addr = inet_addr(tmp);
245 			/* Addr will always be an ipv4 address (32bits) */
246 			if (addr.s_addr == 0xffffffffUL)
247 				return (NSS_STR_PARSE_PARSE);
248 			else {
249 				(void) memcpy(buffer, (char *)&addr,
250 				    sizeof (struct in_addr));
251 			}
252 		} else
253 			return (NSS_STR_PARSE_ERANGE);
254 	}
255 
256 	while (p < limit && isspace(*p))	/* skip intermediate */
257 		p++;
258 
259 	if (mask) {
260 		for (start = p, i = 0; p < limit && !isspace(*p); p++)
261 			i++;
262 		if (p <= limit) {
263 			if ((i + 1) > NSS_LINELEN_NETMASKS)
264 				return (NSS_STR_PARSE_ERANGE);
265 			(void) memcpy(tmp, start, i);
266 			tmp[i] = '\0';
267 			addr.s_addr = inet_addr(tmp);
268 			/* Addr will always be an ipv4 address (32bits) */
269 			if (addr.s_addr == 0xffffffffUL)
270 				retval = NSS_STR_PARSE_PARSE;
271 			else {
272 				mask->s_addr = addr.s_addr;
273 				retval = NSS_STR_PARSE_SUCCESS;
274 			}
275 		}
276 	}
277 
278 	return (retval);
279 }
280