Lines Matching defs:*
0 /* Shared library add-on to iptables to add string matching support.
3 * Copyright (C) 2000 Emmanuel Roger <winfield@freegates.be>
5 * 2005-08-05 Pablo Neira Ayuso <pablo@eurodev.net>
6 * - reimplemented to use new string matching iptables match
7 * - add functionality to match packets by using window offsets
8 * - add functionality to select the string matching algorithm
10 * ChangeLog
11 * 29.12.2003: Michael Rash <mbr@cipherdyne.org>
12 * Fixed iptables save/restore for ascii strings
13 * that contain space chars, and hex strings that
14 * contain embedded NULL chars. Updated to print
15 * strings in hex mode if any non-printable char
16 * is contained within the string.
18 * 27.01.2001: Gianni Tedesco <gianni@ecsc.co.uk>
19 * Changed --tos to --string in save(). Also
20 * updated to work with slightly modified
21 * ipt_string_info.
23 #define _GNU_SOURCE 1 /* strnlen for older glibcs */
24 #include <stdio.h>
25 #include <string.h>
26 #include <stdlib.h>
27 #include <ctype.h>
28 #include <xtables.h>
29 #include <linux/netfilter/xt_string.h>
31 enum {
32 O_FROM = 0,
33 O_TO,
34 O_ALGO,
35 O_ICASE,
36 O_STRING,
37 O_HEX_STRING,
38 F_STRING = 1 << O_STRING,
39 F_HEX_STRING = 1 << O_HEX_STRING,
40 F_OP_ANY = F_STRING | F_HEX_STRING,
43 static void string_help(void)
45 printf(
46 "string match options:\n"
47 "--from Offset to start searching from\n"
48 "--to Offset to stop searching\n"
49 "--algo Algorithm\n"
50 "--icase Ignore case (default: 0)\n"
51 "[!] --string string Match a string in a packet\n"
52 "[!] --hex-string string Match a hex string in a packet\n");
55 #define s struct xt_string_info
56 static const struct xt_option_entry string_opts[] = {
57 {.name = "from", .id = O_FROM, .type = XTTYPE_UINT16,
58 .flags = XTOPT_PUT, XTOPT_POINTER(s, from_offset)},
59 {.name = "to", .id = O_TO, .type = XTTYPE_UINT16,
60 .flags = XTOPT_PUT, XTOPT_POINTER(s, to_offset)},
61 {.name = "algo", .id = O_ALGO, .type = XTTYPE_STRING,
62 .flags = XTOPT_MAND | XTOPT_PUT, XTOPT_POINTER(s, algo)},
63 {.name = "string", .id = O_STRING, .type = XTTYPE_STRING,
64 .flags = XTOPT_INVERT, .excl = F_HEX_STRING},
65 {.name = "hex-string", .id = O_HEX_STRING, .type = XTTYPE_STRING,
66 .flags = XTOPT_INVERT, .excl = F_STRING},
67 {.name = "icase", .id = O_ICASE, .type = XTTYPE_NONE},
68 XTOPT_TABLEEND,
70 #undef s
72 static void string_init(struct xt_entry_match *m)
74 struct xt_string_info *i = (struct xt_string_info *) m->data;
76 i->to_offset = UINT16_MAX;
79 static void
80 parse_string(const char *s, struct xt_string_info *info)
82 /* xt_string does not need \0 at the end of the pattern */
83 if (strlen(s) <= XT_STRING_MAX_PATTERN_SIZE) {
84 strncpy(info->pattern, s, XT_STRING_MAX_PATTERN_SIZE);
85 info->patlen = strnlen(s, XT_STRING_MAX_PATTERN_SIZE);
86 return;
88 xtables_error(PARAMETER_PROBLEM, "STRING too long \"%s\"", s);
91 static void
92 parse_hex_string(const char *s, struct xt_string_info *info)
94 int i=0, slen, sindex=0, schar;
95 short hex_f = 0, literal_f = 0;
96 char hextmp[3];
98 slen = strlen(s);
100 if (slen == 0) {
101 xtables_error(PARAMETER_PROBLEM,
102 "STRING must contain at least one char");
105 while (i < slen) {
106 if (s[i] == '\\' && !hex_f) {
107 literal_f = 1;
108 } else if (s[i] == '\\') {
109 xtables_error(PARAMETER_PROBLEM,
110 "Cannot include literals in hex data");
111 } else if (s[i] == '|') {
112 if (hex_f)
113 hex_f = 0;
114 else {
115 hex_f = 1;
116 /* get past any initial whitespace just after the '|' */
117 while (s[i+1] == ' ')
118 i++;
120 if (i+1 >= slen)
121 break;
122 else
123 i++; /* advance to the next character */
126 if (literal_f) {
127 if (i+1 >= slen) {
128 xtables_error(PARAMETER_PROBLEM,
129 "Bad literal placement at end of string");
131 info->pattern[sindex] = s[i+1];
132 i += 2; /* skip over literal char */
133 literal_f = 0;
134 } else if (hex_f) {
135 if (i+1 >= slen) {
136 xtables_error(PARAMETER_PROBLEM,
137 "Odd number of hex digits");
139 if (i+2 >= slen) {
140 /* must end with a "|" */
141 xtables_error(PARAMETER_PROBLEM, "Invalid hex block");
143 if (! isxdigit(s[i])) /* check for valid hex char */
144 xtables_error(PARAMETER_PROBLEM, "Invalid hex char '%c'", s[i]);
145 if (! isxdigit(s[i+1])) /* check for valid hex char */
146 xtables_error(PARAMETER_PROBLEM, "Invalid hex char '%c'", s[i+1]);
147 hextmp[0] = s[i];
148 hextmp[1] = s[i+1];
149 hextmp[2] = '\0';
150 if (! sscanf(hextmp, "%x", &schar))
151 xtables_error(PARAMETER_PROBLEM,
152 "Invalid hex char `%c'", s[i]);
153 info->pattern[sindex] = (char) schar;
154 if (s[i+2] == ' ')
155 i += 3; /* spaces included in the hex block */
156 else
157 i += 2;
158 } else { /* the char is not part of hex data, so just copy */
159 info->pattern[sindex] = s[i];
160 i++;
162 if (sindex > XT_STRING_MAX_PATTERN_SIZE)
163 xtables_error(PARAMETER_PROBLEM, "STRING too long \"%s\"", s);
164 sindex++;
166 info->patlen = sindex;
169 static void string_parse(struct xt_option_call *cb)
171 struct xt_string_info *stringinfo = cb->data;
172 const unsigned int revision = (*cb->match)->u.user.revision;
174 xtables_option_parse(cb);
175 switch (cb->entry->id) {
176 case O_STRING:
177 parse_string(cb->arg, stringinfo);
178 if (cb->invert) {
179 if (revision == 0)
180 stringinfo->u.v0.invert = 1;
181 else
182 stringinfo->u.v1.flags |= XT_STRING_FLAG_INVERT;
184 break;
185 case O_HEX_STRING:
186 parse_hex_string(cb->arg, stringinfo); /* sets length */
187 if (cb->invert) {
188 if (revision == 0)
189 stringinfo->u.v0.invert = 1;
190 else
191 stringinfo->u.v1.flags |= XT_STRING_FLAG_INVERT;
193 break;
194 case O_ICASE:
195 if (revision == 0)
196 xtables_error(VERSION_PROBLEM,
197 "Kernel doesn't support --icase");
199 stringinfo->u.v1.flags |= XT_STRING_FLAG_IGNORECASE;
200 break;
204 static void string_check(struct xt_fcheck_call *cb)
206 if (!(cb->xflags & F_OP_ANY))
207 xtables_error(PARAMETER_PROBLEM,
208 "STRING match: You must specify `--string' or "
209 "`--hex-string'");
212 /* Test to see if the string contains non-printable chars or quotes */
213 static unsigned short int
214 is_hex_string(const char *str, const unsigned short int len)
216 unsigned int i;
217 for (i=0; i < len; i++)
218 if (! isprint(str[i]))
219 return 1; /* string contains at least one non-printable char */
220 /* use hex output if the last char is a "\" */
221 if (str[len-1] == '\\')
222 return 1;
223 return 0;
226 /* Print string with "|" chars included as one would pass to --hex-string */
227 static void
228 print_hex_string(const char *str, const unsigned short int len)
230 unsigned int i;
231 /* start hex block */
232 printf(" \"|");
233 for (i=0; i < len; i++)
234 printf("%02x", (unsigned char)str[i]);
235 /* close hex block */
236 printf("|\"");
239 static void
240 print_string(const char *str, const unsigned short int len)
242 unsigned int i;
243 printf(" \"");
244 for (i=0; i < len; i++) {
245 if (str[i] == '\"' || str[i] == '\\')
246 putchar('\\');
247 printf("%c", (unsigned char) str[i]);
249 printf("\""); /* closing quote */
252 static void
253 string_print(const void *ip, const struct xt_entry_match *match, int numeric)
255 const struct xt_string_info *info =
256 (const struct xt_string_info*) match->data;
257 const int revision = match->u.user.revision;
258 int invert = (revision == 0 ? info->u.v0.invert :
259 info->u.v1.flags & XT_STRING_FLAG_INVERT);
261 if (is_hex_string(info->pattern, info->patlen)) {
262 printf(" STRING match %s", invert ? "!" : "");
263 print_hex_string(info->pattern, info->patlen);
264 } else {
265 printf(" STRING match %s", invert ? "!" : "");
266 print_string(info->pattern, info->patlen);
268 printf(" ALGO name %s", info->algo);
269 if (info->from_offset != 0)
270 printf(" FROM %u", info->from_offset);
271 if (info->to_offset != 0)
272 printf(" TO %u", info->to_offset);
273 if (revision > 0 && info->u.v1.flags & XT_STRING_FLAG_IGNORECASE)
274 printf(" ICASE");
277 static void string_save(const void *ip, const struct xt_entry_match *match)
279 const struct xt_string_info *info =
280 (const struct xt_string_info*) match->data;
281 const int revision = match->u.user.revision;
282 int invert = (revision == 0 ? info->u.v0.invert :
283 info->u.v1.flags & XT_STRING_FLAG_INVERT);
285 if (is_hex_string(info->pattern, info->patlen)) {
286 printf("%s --hex-string", (invert) ? " !" : "");
287 print_hex_string(info->pattern, info->patlen);
288 } else {
289 printf("%s --string", (invert) ? " !": "");
290 print_string(info->pattern, info->patlen);
292 printf(" --algo %s", info->algo);
293 if (info->from_offset != 0)
294 printf(" --from %u", info->from_offset);
295 if (info->to_offset != 0)
296 printf(" --to %u", info->to_offset);
297 if (revision > 0 && info->u.v1.flags & XT_STRING_FLAG_IGNORECASE)
298 printf(" --icase");
302 static struct xtables_match string_mt_reg[] = {
304 .name = "string",
305 .revision = 0,
306 .family = NFPROTO_UNSPEC,
307 .version = XTABLES_VERSION,
308 .size = XT_ALIGN(sizeof(struct xt_string_info)),
309 .userspacesize = offsetof(struct xt_string_info, config),
310 .help = string_help,
311 .init = string_init,
312 .print = string_print,
313 .save = string_save,
314 .x6_parse = string_parse,
315 .x6_fcheck = string_check,
316 .x6_options = string_opts,
319 .name = "string",
320 .revision = 1,
321 .family = NFPROTO_UNSPEC,
322 .version = XTABLES_VERSION,
323 .size = XT_ALIGN(sizeof(struct xt_string_info)),
324 .userspacesize = offsetof(struct xt_string_info, config),
325 .help = string_help,
326 .init = string_init,
327 .print = string_print,
328 .save = string_save,
329 .x6_parse = string_parse,
330 .x6_fcheck = string_check,
331 .x6_options = string_opts,
335 void _init(void)
337 xtables_register_matches(string_mt_reg, ARRAY_SIZE(string_mt_reg));