1#include <stdint.h>
2#include <stdio.h>
3#include <string.h>
4#include <xtables.h>
5#include <limits.h> /* INT_MAX in ip6_tables.h */
6#include <linux/netfilter_ipv4/ip_tables.h>
7
8/* special hack for icmp-type 'any':
9 * Up to kernel <=2.4.20 the problem was:
10 * '-p icmp ' matches all icmp packets
11 * '-p icmp -m icmp' matches _only_ ICMP type 0 :(
12 * This is now fixed by initializing the field * to icmp type 0xFF
13 * See: https://bugzilla.netfilter.org/cgi-bin/bugzilla/show_bug.cgi?id=37
14 */
15
16enum {
17	O_ICMP_TYPE = 0,
18};
19
20struct icmp_names {
21	const char *name;
22	uint8_t type;
23	uint8_t code_min, code_max;
24};
25
26static const struct icmp_names icmp_codes[] = {
27	{ "any", 0xFF, 0, 0xFF },
28	{ "echo-reply", 0, 0, 0xFF },
29	/* Alias */ { "pong", 0, 0, 0xFF },
30
31	{ "destination-unreachable", 3, 0, 0xFF },
32	{   "network-unreachable", 3, 0, 0 },
33	{   "host-unreachable", 3, 1, 1 },
34	{   "protocol-unreachable", 3, 2, 2 },
35	{   "port-unreachable", 3, 3, 3 },
36	{   "fragmentation-needed", 3, 4, 4 },
37	{   "source-route-failed", 3, 5, 5 },
38	{   "network-unknown", 3, 6, 6 },
39	{   "host-unknown", 3, 7, 7 },
40	{   "network-prohibited", 3, 9, 9 },
41	{   "host-prohibited", 3, 10, 10 },
42	{   "TOS-network-unreachable", 3, 11, 11 },
43	{   "TOS-host-unreachable", 3, 12, 12 },
44	{   "communication-prohibited", 3, 13, 13 },
45	{   "host-precedence-violation", 3, 14, 14 },
46	{   "precedence-cutoff", 3, 15, 15 },
47
48	{ "source-quench", 4, 0, 0xFF },
49
50	{ "redirect", 5, 0, 0xFF },
51	{   "network-redirect", 5, 0, 0 },
52	{   "host-redirect", 5, 1, 1 },
53	{   "TOS-network-redirect", 5, 2, 2 },
54	{   "TOS-host-redirect", 5, 3, 3 },
55
56	{ "echo-request", 8, 0, 0xFF },
57	/* Alias */ { "ping", 8, 0, 0xFF },
58
59	{ "router-advertisement", 9, 0, 0xFF },
60
61	{ "router-solicitation", 10, 0, 0xFF },
62
63	{ "time-exceeded", 11, 0, 0xFF },
64	/* Alias */ { "ttl-exceeded", 11, 0, 0xFF },
65	{   "ttl-zero-during-transit", 11, 0, 0 },
66	{   "ttl-zero-during-reassembly", 11, 1, 1 },
67
68	{ "parameter-problem", 12, 0, 0xFF },
69	{   "ip-header-bad", 12, 0, 0 },
70	{   "required-option-missing", 12, 1, 1 },
71
72	{ "timestamp-request", 13, 0, 0xFF },
73
74	{ "timestamp-reply", 14, 0, 0xFF },
75
76	{ "address-mask-request", 17, 0, 0xFF },
77
78	{ "address-mask-reply", 18, 0, 0xFF }
79};
80
81static void
82print_icmptypes(void)
83{
84	unsigned int i;
85	printf("Valid ICMP Types:");
86
87	for (i = 0; i < ARRAY_SIZE(icmp_codes); ++i) {
88		if (i && icmp_codes[i].type == icmp_codes[i-1].type) {
89			if (icmp_codes[i].code_min == icmp_codes[i-1].code_min
90			    && (icmp_codes[i].code_max
91				== icmp_codes[i-1].code_max))
92				printf(" (%s)", icmp_codes[i].name);
93			else
94				printf("\n   %s", icmp_codes[i].name);
95		}
96		else
97			printf("\n%s", icmp_codes[i].name);
98	}
99	printf("\n");
100}
101
102static void icmp_help(void)
103{
104	printf(
105"icmp match options:\n"
106"[!] --icmp-type typename	match icmp type\n"
107"[!] --icmp-type type[/code]	(or numeric type or type/code)\n");
108	print_icmptypes();
109}
110
111static const struct xt_option_entry icmp_opts[] = {
112	{.name = "icmp-type", .id = O_ICMP_TYPE, .type = XTTYPE_STRING,
113	 .flags = XTOPT_MAND | XTOPT_INVERT},
114	XTOPT_TABLEEND,
115};
116
117static void
118parse_icmp(const char *icmptype, uint8_t *type, uint8_t code[])
119{
120	static const unsigned int limit = ARRAY_SIZE(icmp_codes);
121	unsigned int match = limit;
122	unsigned int i;
123
124	for (i = 0; i < limit; i++) {
125		if (strncasecmp(icmp_codes[i].name, icmptype, strlen(icmptype))
126		    == 0) {
127			if (match != limit)
128				xtables_error(PARAMETER_PROBLEM,
129					   "Ambiguous ICMP type `%s':"
130					   " `%s' or `%s'?",
131					   icmptype,
132					   icmp_codes[match].name,
133					   icmp_codes[i].name);
134			match = i;
135		}
136	}
137
138	if (match != limit) {
139		*type = icmp_codes[match].type;
140		code[0] = icmp_codes[match].code_min;
141		code[1] = icmp_codes[match].code_max;
142	} else {
143		char *slash;
144		char buffer[strlen(icmptype) + 1];
145		unsigned int number;
146
147		strcpy(buffer, icmptype);
148		slash = strchr(buffer, '/');
149
150		if (slash)
151			*slash = '\0';
152
153		if (!xtables_strtoui(buffer, NULL, &number, 0, UINT8_MAX))
154			xtables_error(PARAMETER_PROBLEM,
155				   "Invalid ICMP type `%s'\n", buffer);
156		*type = number;
157		if (slash) {
158			if (!xtables_strtoui(slash+1, NULL, &number, 0, UINT8_MAX))
159				xtables_error(PARAMETER_PROBLEM,
160					   "Invalid ICMP code `%s'\n",
161					   slash+1);
162			code[0] = code[1] = number;
163		} else {
164			code[0] = 0;
165			code[1] = 0xFF;
166		}
167	}
168}
169
170static void icmp_init(struct xt_entry_match *m)
171{
172	struct ipt_icmp *icmpinfo = (struct ipt_icmp *)m->data;
173
174	icmpinfo->type = 0xFF;
175	icmpinfo->code[1] = 0xFF;
176}
177
178static void icmp_parse(struct xt_option_call *cb)
179{
180	struct ipt_icmp *icmpinfo = cb->data;
181
182	xtables_option_parse(cb);
183	parse_icmp(cb->arg, &icmpinfo->type, icmpinfo->code);
184	if (cb->invert)
185		icmpinfo->invflags |= IPT_ICMP_INV;
186}
187
188static void print_icmptype(uint8_t type,
189			   uint8_t code_min, uint8_t code_max,
190			   int invert,
191			   int numeric)
192{
193	if (!numeric) {
194		unsigned int i;
195
196		for (i = 0; i < ARRAY_SIZE(icmp_codes); ++i)
197			if (icmp_codes[i].type == type
198			    && icmp_codes[i].code_min == code_min
199			    && icmp_codes[i].code_max == code_max)
200				break;
201
202		if (i != ARRAY_SIZE(icmp_codes)) {
203			printf(" %s%s",
204			       invert ? "!" : "",
205			       icmp_codes[i].name);
206			return;
207		}
208	}
209
210	if (invert)
211		printf(" !");
212
213	printf("type %u", type);
214	if (code_min == code_max)
215		printf(" code %u", code_min);
216	else if (code_min != 0 || code_max != 0xFF)
217		printf(" codes %u-%u", code_min, code_max);
218}
219
220static void icmp_print(const void *ip, const struct xt_entry_match *match,
221                       int numeric)
222{
223	const struct ipt_icmp *icmp = (struct ipt_icmp *)match->data;
224
225	printf(" icmp");
226	print_icmptype(icmp->type, icmp->code[0], icmp->code[1],
227		       icmp->invflags & IPT_ICMP_INV,
228		       numeric);
229
230	if (icmp->invflags & ~IPT_ICMP_INV)
231		printf(" Unknown invflags: 0x%X",
232		       icmp->invflags & ~IPT_ICMP_INV);
233}
234
235static void icmp_save(const void *ip, const struct xt_entry_match *match)
236{
237	const struct ipt_icmp *icmp = (struct ipt_icmp *)match->data;
238
239	if (icmp->invflags & IPT_ICMP_INV)
240		printf(" !");
241
242	/* special hack for 'any' case */
243	if (icmp->type == 0xFF) {
244		printf(" --icmp-type any");
245	} else {
246		printf(" --icmp-type %u", icmp->type);
247		if (icmp->code[0] != 0 || icmp->code[1] != 0xFF)
248			printf("/%u", icmp->code[0]);
249	}
250}
251
252static struct xtables_match icmp_mt_reg = {
253	.name		= "icmp",
254	.version	= XTABLES_VERSION,
255	.family		= NFPROTO_IPV4,
256	.size		= XT_ALIGN(sizeof(struct ipt_icmp)),
257	.userspacesize	= XT_ALIGN(sizeof(struct ipt_icmp)),
258	.help		= icmp_help,
259	.init		= icmp_init,
260	.print		= icmp_print,
261	.save		= icmp_save,
262	.x6_parse	= icmp_parse,
263	.x6_options	= icmp_opts,
264};
265
266void _init(void)
267{
268	xtables_register_match(&icmp_mt_reg);
269}
270