libip6t_ipv6header.c revision 80fe35d6339b53a12ddaec41885613e4e37ed031 
1/* ipv6header match - matches IPv6 packets based
2on whether they contain certain headers */
3
4/* Original idea: Brad Chapman
5 * Rewritten by: Andras Kis-Szabo <kisza@sch.bme.hu> */
6
7#include <getopt.h>
8#include <ip6tables.h>
9#include <stddef.h>
10#include <stdio.h>
11#include <stdlib.h>
12#include <string.h>
13#include <netdb.h>
14#include <sys/types.h>
15
16#include <linux/netfilter_ipv6/ip6_tables.h>
17#include <linux/netfilter_ipv6/ip6t_ipv6header.h>
18
19/* This maybe required
20#include <linux/in.h>
21#include <linux/in6.h>
22*/
23
24
25/* A few hardcoded protocols for 'all' and in case the user has no
26 *    /etc/protocols */
27struct pprot {
28	char *name;
29	u_int8_t num;
30};
31
32struct numflag {
33	u_int8_t proto;
34	u_int8_t flag;
35};
36
37static const struct pprot chain_protos[] = {
38	{ "hop-by-hop", IPPROTO_HOPOPTS },
39	{ "protocol", IPPROTO_RAW },
40	{ "hop", IPPROTO_HOPOPTS },
41	{ "dst", IPPROTO_DSTOPTS },
42	{ "route", IPPROTO_ROUTING },
43	{ "frag", IPPROTO_FRAGMENT },
44	{ "auth", IPPROTO_AH },
45	{ "esp", IPPROTO_ESP },
46	{ "none", IPPROTO_NONE },
47	{ "prot", IPPROTO_RAW },
48	{ "0", IPPROTO_HOPOPTS },
49	{ "60", IPPROTO_DSTOPTS },
50	{ "43", IPPROTO_ROUTING },
51	{ "44", IPPROTO_FRAGMENT },
52	{ "51", IPPROTO_AH },
53	{ "50", IPPROTO_ESP },
54	{ "59", IPPROTO_NONE },
55	{ "255", IPPROTO_RAW },
56	/* { "all", 0 }, */
57};
58
59static const struct numflag chain_flags[] = {
60	{ IPPROTO_HOPOPTS, MASK_HOPOPTS },
61	{ IPPROTO_DSTOPTS, MASK_DSTOPTS },
62	{ IPPROTO_ROUTING, MASK_ROUTING },
63	{ IPPROTO_FRAGMENT, MASK_FRAGMENT },
64	{ IPPROTO_AH, MASK_AH },
65	{ IPPROTO_ESP, MASK_ESP },
66	{ IPPROTO_NONE, MASK_NONE },
67	{ IPPROTO_RAW, MASK_PROTO },
68};
69
70static char *
71proto_to_name(u_int8_t proto, int nolookup)
72{
73        unsigned int i;
74
75        if (proto && !nolookup) {
76                struct protoent *pent = getprotobynumber(proto);
77                if (pent)
78                        return pent->p_name;
79        }
80
81        for (i = 0; i < sizeof(chain_protos)/sizeof(struct pprot); i++)
82                if (chain_protos[i].num == proto)
83                        return chain_protos[i].name;
84
85        return NULL;
86}
87
88static u_int16_t
89name_to_proto(const char *s)
90{
91        unsigned int proto=0;
92        struct protoent *pent;
93
94        if ((pent = getprotobyname(s)))
95        	proto = pent->p_proto;
96        else {
97        	unsigned int i;
98        	for (i = 0;
99        		i < sizeof(chain_protos)/sizeof(struct pprot);
100        		i++) {
101        		if (strcmp(s, chain_protos[i].name) == 0) {
102        			proto = chain_protos[i].num;
103        			break;
104        		}
105        	}
106
107        	if (i == sizeof(chain_protos)/sizeof(struct pprot))
108        		exit_error(PARAMETER_PROBLEM,
109        			"unknown header `%s' specified",
110        			s);
111        }
112
113        return (u_int16_t)proto;
114}
115
116static unsigned int
117add_proto_to_mask(int proto){
118	unsigned int i=0, flag=0;
119
120	for (i = 0;
121		i < sizeof(chain_flags)/sizeof(struct numflag);
122		i++) {
123			if (proto == chain_flags[i].proto){
124				flag = chain_flags[i].flag;
125				break;
126			}
127	}
128
129	if (i == sizeof(chain_flags)/sizeof(struct numflag))
130		exit_error(PARAMETER_PROBLEM,
131		"unknown header `%d' specified",
132		proto);
133
134	return flag;
135}
136
137static void
138help(void)
139{
140	printf(
141"ipv6header v%s match options:\n"
142"--header [!] headers     Type of header to match, by name\n"
143"                         names: hop,dst,route,frag,auth,esp,none,proto\n"
144"                    long names: hop-by-hop,ipv6-opts,ipv6-route,\n"
145"                                ipv6-frag,ah,esp,ipv6-nonxt,protocol\n"
146"                       numbers: 0,60,43,44,51,50,59\n"
147"--soft                    The header CONTAINS the specified extensions\n",
148	IPTABLES_VERSION);
149}
150
151static struct option opts[] = {
152	{ "header", 1, 0, '1' },
153	{ "soft", 0, 0, '2' },
154	{ 0 }
155};
156
157static void
158init(struct ip6t_entry_match *m, unsigned int *nfcache)
159{
160	struct ip6t_ipv6header_info *info = (struct ip6t_ipv6header_info *)m->data;
161
162	info->matchflags = 0x00;
163	info->invflags = 0x00;
164	info->modeflag = 0x00;
165	/* No caching (yet) */
166	*nfcache |= NFC_UNKNOWN;
167}
168
169static unsigned int
170parse_header(const char *flags) {
171        unsigned int ret = 0;
172        char *ptr;
173        char *buffer;
174
175        buffer = strdup(flags);
176
177        for (ptr = strtok(buffer, ","); ptr; ptr = strtok(NULL, ","))
178		ret |= add_proto_to_mask(name_to_proto(ptr));
179
180        free(buffer);
181        return ret;
182}
183
184#define IPV6_HDR_HEADER	0x01
185#define IPV6_HDR_SOFT	0x02
186
187/* Parses command options; returns 0 if it ate an option */
188static int
189parse(int c, char **argv, int invert, unsigned int *flags,
190      const struct ip6t_entry *entry,
191      unsigned int *nfcache,
192      struct ip6t_entry_match **match)
193{
194	struct ip6t_ipv6header_info *info = (struct ip6t_ipv6header_info *)(*match)->data;
195
196	switch (c) {
197		case '1' :
198			/* Parse the provided header names */
199			if (*flags & IPV6_HDR_HEADER)
200				exit_error(PARAMETER_PROBLEM,
201					"Only one `--header' allowed");
202
203			check_inverse(optarg, &invert, &optind, 0);
204
205			if (! (info->matchflags = parse_header(argv[optind-1])) )
206				exit_error(PARAMETER_PROBLEM, "ip6t_ipv6header: cannot parse header names");
207
208			if (invert)
209				info->invflags |= 0xFF;
210			*flags |= IPV6_HDR_HEADER;
211			break;
212		case '2' :
213			/* Soft-mode requested? */
214			if (*flags & IPV6_HDR_SOFT)
215				exit_error(PARAMETER_PROBLEM,
216					"Only one `--soft' allowed");
217
218			info->modeflag |= 0xFF;
219			*flags |= IPV6_HDR_SOFT;
220			break;
221		default:
222			return 0;
223	}
224
225	return 1;
226}
227
228/* Checks the flags variable */
229static void
230final_check(unsigned int flags)
231{
232	if (!flags) exit_error(PARAMETER_PROBLEM, "ip6t_ipv6header: no options specified");
233}
234
235static void
236print_header(u_int8_t flags){
237        int have_flag = 0;
238
239        while (flags) {
240                unsigned int i;
241
242                for (i = 0; (flags & chain_flags[i].flag) == 0; i++);
243
244                if (have_flag)
245                        printf(",");
246
247                printf("%s", proto_to_name(chain_flags[i].proto,0));
248                have_flag = 1;
249
250                flags &= ~chain_flags[i].flag;
251        }
252
253        if (!have_flag)
254                printf("NONE");
255}
256
257/* Prints out the match */
258static void
259print(const struct ip6t_ip6 *ip,
260      const struct ip6t_entry_match *match,
261      int numeric)
262{
263	const struct ip6t_ipv6header_info *info = (const struct ip6t_ipv6header_info *)match->data;
264	printf("ipv6header ");
265
266        if (info->matchflags || info->invflags) {
267                printf("flags:%s", info->invflags ? "!" : "");
268                if (numeric)
269                        printf("0x%02X ", info->matchflags);
270                else {
271                        print_header(info->matchflags);
272                        printf(" ");
273                }
274        }
275
276	if (info->modeflag)
277		printf("soft ");
278
279	return;
280}
281
282/* Saves the match */
283static void
284save(const struct ip6t_ip6 *ip,
285     const struct ip6t_entry_match *match)
286{
287
288	const struct ip6t_ipv6header_info *info = (const struct ip6t_ipv6header_info *)match->data;
289
290	printf("--header ");
291	printf("%s", info->invflags ? "!" : "");
292	print_header(info->matchflags);
293	printf(" ");
294	if (info->modeflag)
295		printf("--soft ");
296
297	return;
298}
299
300static
301struct ip6tables_match ipv6header
302= { NULL,
303    "ipv6header",
304    IPTABLES_VERSION,
305    IP6T_ALIGN(sizeof(struct ip6t_ipv6header_info)),
306    IP6T_ALIGN(sizeof(struct ip6t_ipv6header_info)),
307    &help,
308    &init,
309    &parse,
310    &final_check,
311    &print,
312    &save,
313    opts
314};
315
316void _init(void)
317{
318	register_match6(&ipv6header);
319}
320