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 <ip6tables.h>
9 #include <linux/netfilter_ipv6/ip6t_frag.h>
10
11 /* Function which prints out usage message. */
12 static void
help(void)13 help(void)
14 {
15 printf(
16 "FRAG v%s options:\n"
17 " --fragid [!] id[:id] match the id (range)\n"
18 " --fraglen [!] length total length of this header\n"
19 " --fragres check the reserved filed, too\n"
20 " --fragfirst matches on the first fragment\n"
21 " [--fragmore|--fraglast] there are more fragments or this\n"
22 " is the last one\n",
23 IPTABLES_VERSION);
24 }
25
26 static struct option opts[] = {
27 { .name = "fragid", .has_arg = 1, .flag = 0, .val = '1' },
28 { .name = "fraglen", .has_arg = 1, .flag = 0, .val = '2' },
29 { .name = "fragres", .has_arg = 0, .flag = 0, .val = '3' },
30 { .name = "fragfirst", .has_arg = 0, .flag = 0, .val = '4' },
31 { .name = "fragmore", .has_arg = 0, .flag = 0, .val = '5' },
32 { .name = "fraglast", .has_arg = 0, .flag = 0, .val = '6' },
33 { .name = 0 }
34 };
35
36 static u_int32_t
parse_frag_id(const char * idstr,const char * typestr)37 parse_frag_id(const char *idstr, const char *typestr)
38 {
39 unsigned long int id;
40 char* ep;
41
42 id = strtoul(idstr, &ep, 0);
43
44 if ( idstr == ep ) {
45 exit_error(PARAMETER_PROBLEM,
46 "FRAG no valid digits in %s `%s'", typestr, idstr);
47 }
48 if ( id == ULONG_MAX && errno == ERANGE ) {
49 exit_error(PARAMETER_PROBLEM,
50 "%s `%s' specified too big: would overflow",
51 typestr, idstr);
52 }
53 if ( *idstr != '\0' && *ep != '\0' ) {
54 exit_error(PARAMETER_PROBLEM,
55 "FRAG error parsing %s `%s'", typestr, idstr);
56 }
57 return (u_int32_t) id;
58 }
59
60 static void
parse_frag_ids(const char * idstring,u_int32_t * ids)61 parse_frag_ids(const char *idstring, u_int32_t *ids)
62 {
63 char *buffer;
64 char *cp;
65
66 buffer = strdup(idstring);
67 if ((cp = strchr(buffer, ':')) == NULL)
68 ids[0] = ids[1] = parse_frag_id(buffer,"id");
69 else {
70 *cp = '\0';
71 cp++;
72
73 ids[0] = buffer[0] ? parse_frag_id(buffer,"id") : 0;
74 ids[1] = cp[0] ? parse_frag_id(cp,"id") : 0xFFFFFFFF;
75 }
76 free(buffer);
77 }
78
79 /* Initialize the match. */
80 static void
init(struct ip6t_entry_match * m,unsigned int * nfcache)81 init(struct ip6t_entry_match *m, unsigned int *nfcache)
82 {
83 struct ip6t_frag *fraginfo = (struct ip6t_frag *)m->data;
84
85 fraginfo->ids[0] = 0x0L;
86 fraginfo->ids[1] = 0xFFFFFFFF;
87 fraginfo->hdrlen = 0;
88 fraginfo->flags = 0;
89 fraginfo->invflags = 0;
90 }
91
92 /* Function which parses command options; returns true if it
93 ate an option */
94 static int
parse(int c,char ** argv,int invert,unsigned int * flags,const struct ip6t_entry * entry,unsigned int * nfcache,struct ip6t_entry_match ** match)95 parse(int c, char **argv, int invert, unsigned int *flags,
96 const struct ip6t_entry *entry,
97 unsigned int *nfcache,
98 struct ip6t_entry_match **match)
99 {
100 struct ip6t_frag *fraginfo = (struct ip6t_frag *)(*match)->data;
101
102 switch (c) {
103 case '1':
104 if (*flags & IP6T_FRAG_IDS)
105 exit_error(PARAMETER_PROBLEM,
106 "Only one `--fragid' allowed");
107 check_inverse(optarg, &invert, &optind, 0);
108 parse_frag_ids(argv[optind-1], fraginfo->ids);
109 if (invert)
110 fraginfo->invflags |= IP6T_FRAG_INV_IDS;
111 fraginfo->flags |= IP6T_FRAG_IDS;
112 *flags |= IP6T_FRAG_IDS;
113 break;
114 case '2':
115 if (*flags & IP6T_FRAG_LEN)
116 exit_error(PARAMETER_PROBLEM,
117 "Only one `--fraglen' allowed");
118 check_inverse(optarg, &invert, &optind, 0);
119 fraginfo->hdrlen = parse_frag_id(argv[optind-1], "length");
120 if (invert)
121 fraginfo->invflags |= IP6T_FRAG_INV_LEN;
122 fraginfo->flags |= IP6T_FRAG_LEN;
123 *flags |= IP6T_FRAG_LEN;
124 break;
125 case '3':
126 if (*flags & IP6T_FRAG_RES)
127 exit_error(PARAMETER_PROBLEM,
128 "Only one `--fragres' allowed");
129 fraginfo->flags |= IP6T_FRAG_RES;
130 *flags |= IP6T_FRAG_RES;
131 break;
132 case '4':
133 if (*flags & IP6T_FRAG_FST)
134 exit_error(PARAMETER_PROBLEM,
135 "Only one `--fragfirst' allowed");
136 fraginfo->flags |= IP6T_FRAG_FST;
137 *flags |= IP6T_FRAG_FST;
138 break;
139 case '5':
140 if (*flags & (IP6T_FRAG_MF|IP6T_FRAG_NMF))
141 exit_error(PARAMETER_PROBLEM,
142 "Only one `--fragmore' or `--fraglast' allowed");
143 fraginfo->flags |= IP6T_FRAG_MF;
144 *flags |= IP6T_FRAG_MF;
145 break;
146 case '6':
147 if (*flags & (IP6T_FRAG_MF|IP6T_FRAG_NMF))
148 exit_error(PARAMETER_PROBLEM,
149 "Only one `--fragmore' or `--fraglast' allowed");
150 fraginfo->flags |= IP6T_FRAG_NMF;
151 *flags |= IP6T_FRAG_NMF;
152 break;
153 default:
154 return 0;
155 }
156
157 return 1;
158 }
159
160 /* Final check; we don't care. */
161 static void
final_check(unsigned int flags)162 final_check(unsigned int flags)
163 {
164 }
165
166 static void
print_ids(const char * name,u_int32_t min,u_int32_t max,int invert)167 print_ids(const char *name, u_int32_t min, u_int32_t max,
168 int invert)
169 {
170 const char *inv = invert ? "!" : "";
171
172 if (min != 0 || max != 0xFFFFFFFF || invert) {
173 printf("%s", name);
174 if (min == max)
175 printf(":%s%u ", inv, min);
176 else
177 printf("s:%s%u:%u ", inv, min, max);
178 }
179 }
180
181 /* Prints out the union ip6t_matchinfo. */
182 static void
print(const struct ip6t_ip6 * ip,const struct ip6t_entry_match * match,int numeric)183 print(const struct ip6t_ip6 *ip,
184 const struct ip6t_entry_match *match, int numeric)
185 {
186 const struct ip6t_frag *frag = (struct ip6t_frag *)match->data;
187
188 printf("frag ");
189 print_ids("id", frag->ids[0], frag->ids[1],
190 frag->invflags & IP6T_FRAG_INV_IDS);
191
192 if (frag->flags & IP6T_FRAG_LEN) {
193 printf("length:%s%u ",
194 frag->invflags & IP6T_FRAG_INV_LEN ? "!" : "",
195 frag->hdrlen);
196 }
197
198 if (frag->flags & IP6T_FRAG_RES)
199 printf("reserved ");
200
201 if (frag->flags & IP6T_FRAG_FST)
202 printf("first ");
203
204 if (frag->flags & IP6T_FRAG_MF)
205 printf("more ");
206
207 if (frag->flags & IP6T_FRAG_NMF)
208 printf("last ");
209
210 if (frag->invflags & ~IP6T_FRAG_INV_MASK)
211 printf("Unknown invflags: 0x%X ",
212 frag->invflags & ~IP6T_FRAG_INV_MASK);
213 }
214
215 /* Saves the union ip6t_matchinfo in parsable form to stdout. */
save(const struct ip6t_ip6 * ip,const struct ip6t_entry_match * match)216 static void save(const struct ip6t_ip6 *ip, const struct ip6t_entry_match *match)
217 {
218 const struct ip6t_frag *fraginfo = (struct ip6t_frag *)match->data;
219
220 if (!(fraginfo->ids[0] == 0
221 && fraginfo->ids[1] == 0xFFFFFFFF)) {
222 printf("--fragid %s",
223 (fraginfo->invflags & IP6T_FRAG_INV_IDS) ? "! " : "");
224 if (fraginfo->ids[0]
225 != fraginfo->ids[1])
226 printf("%u:%u ",
227 fraginfo->ids[0],
228 fraginfo->ids[1]);
229 else
230 printf("%u ",
231 fraginfo->ids[0]);
232 }
233
234 if (fraginfo->flags & IP6T_FRAG_LEN) {
235 printf("--fraglen %s%u ",
236 (fraginfo->invflags & IP6T_FRAG_INV_LEN) ? "! " : "",
237 fraginfo->hdrlen);
238 }
239
240 if (fraginfo->flags & IP6T_FRAG_RES)
241 printf("--fragres ");
242
243 if (fraginfo->flags & IP6T_FRAG_FST)
244 printf("--fragfirst ");
245
246 if (fraginfo->flags & IP6T_FRAG_MF)
247 printf("--fragmore ");
248
249 if (fraginfo->flags & IP6T_FRAG_NMF)
250 printf("--fraglast ");
251 }
252
253 static
254 struct ip6tables_match frag = {
255 .name = "frag",
256 .version = IPTABLES_VERSION,
257 .size = IP6T_ALIGN(sizeof(struct ip6t_frag)),
258 .userspacesize = IP6T_ALIGN(sizeof(struct ip6t_frag)),
259 .help = &help,
260 .init = &init,
261 .parse = &parse,
262 .final_check = &final_check,
263 .print = &print,
264 .save = &save,
265 .extra_opts = opts
266 };
267
268 void
_init(void)269 _init(void)
270 {
271 register_match6(&frag);
272 }
273