libip6t_frag.c revision cea9f71f5618250a38acb21c31fbbf93a752f7d4 
1/* Shared library add-on to ip6tables to add Fragmentation header support. */
2#include <stdio.h>
3#include <netdb.h>
4#include <string.h>
5#include <stdlib.h>
6#include <getopt.h>
7#include <errno.h>
8#include <xtables.h>
9#include <linux/netfilter_ipv6/ip6t_frag.h>
10
11static void frag_help(void)
12{
13	printf(
14"frag match options:\n"
15"[!] --fragid id[:id]           match the id (range)\n"
16"[!] --fraglen length           total length of this header\n"
17" --fragres                     check the reserved filed, too\n"
18" --fragfirst                   matches on the first fragment\n"
19" [--fragmore|--fraglast]       there are more fragments or this\n"
20"                               is the last one\n");
21}
22
23static const struct option frag_opts[] = {
24	{ .name = "fragid",    .has_arg = 1, .val = '1' },
25	{ .name = "fraglen",   .has_arg = 1, .val = '2' },
26	{ .name = "fragres",   .has_arg = 0, .val = '3' },
27	{ .name = "fragfirst", .has_arg = 0, .val = '4' },
28	{ .name = "fragmore",  .has_arg = 0, .val = '5' },
29	{ .name = "fraglast",  .has_arg = 0, .val = '6' },
30	{ .name = NULL }
31};
32
33static u_int32_t
34parse_frag_id(const char *idstr, const char *typestr)
35{
36	unsigned long int id;
37	char* ep;
38
39	id = strtoul(idstr, &ep, 0);
40
41	if ( idstr == ep ) {
42		exit_error(PARAMETER_PROBLEM,
43			   "FRAG no valid digits in %s `%s'", typestr, idstr);
44	}
45	if ( id == ULONG_MAX  && errno == ERANGE ) {
46		exit_error(PARAMETER_PROBLEM,
47			   "%s `%s' specified too big: would overflow",
48			   typestr, idstr);
49	}
50	if ( *idstr != '\0'  && *ep != '\0' ) {
51		exit_error(PARAMETER_PROBLEM,
52			   "FRAG error parsing %s `%s'", typestr, idstr);
53	}
54	return (u_int32_t) id;
55}
56
57static void
58parse_frag_ids(const char *idstring, u_int32_t *ids)
59{
60	char *buffer;
61	char *cp;
62
63	buffer = strdup(idstring);
64	if ((cp = strchr(buffer, ':')) == NULL)
65		ids[0] = ids[1] = parse_frag_id(buffer,"id");
66	else {
67		*cp = '\0';
68		cp++;
69
70		ids[0] = buffer[0] ? parse_frag_id(buffer,"id") : 0;
71		ids[1] = cp[0] ? parse_frag_id(cp,"id") : 0xFFFFFFFF;
72	}
73	free(buffer);
74}
75
76static void frag_init(struct xt_entry_match *m)
77{
78	struct ip6t_frag *fraginfo = (struct ip6t_frag *)m->data;
79
80	fraginfo->ids[0] = 0x0L;
81	fraginfo->ids[1] = 0xFFFFFFFF;
82	fraginfo->hdrlen = 0;
83	fraginfo->flags = 0;
84	fraginfo->invflags = 0;
85}
86
87static int frag_parse(int c, char **argv, int invert, unsigned int *flags,
88                      const void *entry, struct xt_entry_match **match)
89{
90	struct ip6t_frag *fraginfo = (struct ip6t_frag *)(*match)->data;
91
92	switch (c) {
93	case '1':
94		if (*flags & IP6T_FRAG_IDS)
95			exit_error(PARAMETER_PROBLEM,
96				   "Only one `--fragid' allowed");
97		check_inverse(optarg, &invert, &optind, 0);
98		parse_frag_ids(argv[optind-1], fraginfo->ids);
99		if (invert)
100			fraginfo->invflags |= IP6T_FRAG_INV_IDS;
101		fraginfo->flags |= IP6T_FRAG_IDS;
102		*flags |= IP6T_FRAG_IDS;
103		break;
104	case '2':
105		if (*flags & IP6T_FRAG_LEN)
106			exit_error(PARAMETER_PROBLEM,
107				   "Only one `--fraglen' allowed");
108		check_inverse(optarg, &invert, &optind, 0);
109		fraginfo->hdrlen = parse_frag_id(argv[optind-1], "length");
110		if (invert)
111			fraginfo->invflags |= IP6T_FRAG_INV_LEN;
112		fraginfo->flags |= IP6T_FRAG_LEN;
113		*flags |= IP6T_FRAG_LEN;
114		break;
115	case '3':
116		if (*flags & IP6T_FRAG_RES)
117			exit_error(PARAMETER_PROBLEM,
118				   "Only one `--fragres' allowed");
119		fraginfo->flags |= IP6T_FRAG_RES;
120		*flags |= IP6T_FRAG_RES;
121		break;
122	case '4':
123		if (*flags & IP6T_FRAG_FST)
124			exit_error(PARAMETER_PROBLEM,
125				   "Only one `--fragfirst' allowed");
126		fraginfo->flags |= IP6T_FRAG_FST;
127		*flags |= IP6T_FRAG_FST;
128		break;
129	case '5':
130		if (*flags & (IP6T_FRAG_MF|IP6T_FRAG_NMF))
131			exit_error(PARAMETER_PROBLEM,
132			   "Only one `--fragmore' or `--fraglast' allowed");
133		fraginfo->flags |= IP6T_FRAG_MF;
134		*flags |= IP6T_FRAG_MF;
135		break;
136	case '6':
137		if (*flags & (IP6T_FRAG_MF|IP6T_FRAG_NMF))
138			exit_error(PARAMETER_PROBLEM,
139			   "Only one `--fragmore' or `--fraglast' allowed");
140		fraginfo->flags |= IP6T_FRAG_NMF;
141		*flags |= IP6T_FRAG_NMF;
142		break;
143	default:
144		return 0;
145	}
146
147	return 1;
148}
149
150static void
151print_ids(const char *name, u_int32_t min, u_int32_t max,
152	    int invert)
153{
154	const char *inv = invert ? "!" : "";
155
156	if (min != 0 || max != 0xFFFFFFFF || invert) {
157		printf("%s", name);
158		if (min == max)
159			printf(":%s%u ", inv, min);
160		else
161			printf("s:%s%u:%u ", inv, min, max);
162	}
163}
164
165static void frag_print(const void *ip, const struct xt_entry_match *match,
166                       int numeric)
167{
168	const struct ip6t_frag *frag = (struct ip6t_frag *)match->data;
169
170	printf("frag ");
171	print_ids("id", frag->ids[0], frag->ids[1],
172		    frag->invflags & IP6T_FRAG_INV_IDS);
173
174	if (frag->flags & IP6T_FRAG_LEN) {
175		printf("length:%s%u ",
176			frag->invflags & IP6T_FRAG_INV_LEN ? "!" : "",
177			frag->hdrlen);
178	}
179
180	if (frag->flags & IP6T_FRAG_RES)
181		printf("reserved ");
182
183	if (frag->flags & IP6T_FRAG_FST)
184		printf("first ");
185
186	if (frag->flags & IP6T_FRAG_MF)
187		printf("more ");
188
189	if (frag->flags & IP6T_FRAG_NMF)
190		printf("last ");
191
192	if (frag->invflags & ~IP6T_FRAG_INV_MASK)
193		printf("Unknown invflags: 0x%X ",
194		       frag->invflags & ~IP6T_FRAG_INV_MASK);
195}
196
197static void frag_save(const void *ip, const struct xt_entry_match *match)
198{
199	const struct ip6t_frag *fraginfo = (struct ip6t_frag *)match->data;
200
201	if (!(fraginfo->ids[0] == 0
202	    && fraginfo->ids[1] == 0xFFFFFFFF)) {
203		printf("%s--fragid ",
204			(fraginfo->invflags & IP6T_FRAG_INV_IDS) ? "! " : "");
205		if (fraginfo->ids[0]
206		    != fraginfo->ids[1])
207			printf("%u:%u ",
208			       fraginfo->ids[0],
209			       fraginfo->ids[1]);
210		else
211			printf("%u ",
212			       fraginfo->ids[0]);
213	}
214
215	if (fraginfo->flags & IP6T_FRAG_LEN) {
216		printf("%s--fraglen %u ",
217			(fraginfo->invflags & IP6T_FRAG_INV_LEN) ? "! " : "",
218			fraginfo->hdrlen);
219	}
220
221	if (fraginfo->flags & IP6T_FRAG_RES)
222		printf("--fragres ");
223
224	if (fraginfo->flags & IP6T_FRAG_FST)
225		printf("--fragfirst ");
226
227	if (fraginfo->flags & IP6T_FRAG_MF)
228		printf("--fragmore ");
229
230	if (fraginfo->flags & IP6T_FRAG_NMF)
231		printf("--fraglast ");
232}
233
234static struct xtables_match frag_mt6_reg = {
235	.name          = "frag",
236	.version       = XTABLES_VERSION,
237	.family        = NFPROTO_IPV6,
238	.size          = XT_ALIGN(sizeof(struct ip6t_frag)),
239	.userspacesize = XT_ALIGN(sizeof(struct ip6t_frag)),
240	.help          = frag_help,
241	.init          = frag_init,
242	.parse         = frag_parse,
243	.print         = frag_print,
244	.save          = frag_save,
245	.extra_opts    = frag_opts,
246};
247
248void
249_init(void)
250{
251	xtables_register_match(&frag_mt6_reg);
252}
253