/usr/src/xtables-addons-2.10/extensions/libxt_length2.c is in xtables-addons-dkms 2.10-1build1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 | #include <getopt.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <xtables.h>
#include "xt_length2.h"
#include "compat_user.h"
enum {
F_LAYER = 1 << 0,
F_LENGTH = 1 << 1,
XT_LENGTH_LAYER_MASK = XT_LENGTH_LAYER3 | XT_LENGTH_LAYER4 |
XT_LENGTH_LAYER5 | XT_LENGTH_LAYER7,
};
static void length_mt_help(void)
{
printf(
"length match options:\n"
" --layer3 Match against layer3 size (e.g. L4 + IPv6 header)\n"
" --layer4 Match against layer4 size (e.g. L5 + SCTP header)\n"
" --layer5 Match against layer5 size (e.g. L7 + chunk headers)\n"
" --layer7 Match against layer7 payload (e.g. SCTP payload)\n"
"[!] --length n[:n] Match packet length against value or range\n"
" of values (inclusive)\n"
);
}
static const struct option length_mt_opts[] = {
{.name = "layer3", .has_arg = false, .val = '3'},
{.name = "layer4", .has_arg = false, .val = '4'},
{.name = "layer5", .has_arg = false, .val = '5'},
{.name = "layer7", .has_arg = false, .val = '7'},
{.name = "length", .has_arg = true, .val = '='},
{NULL},
};
static void length_mt_init(struct xt_entry_match *match)
{
struct xt_length_mtinfo2 *info = (void *)match->data;
info->flags = XT_LENGTH_LAYER3;
}
static int length_mt_parse(int c, char **argv, int invert, unsigned int *flags,
const void *entry, struct xt_entry_match **match)
{
struct xt_length_mtinfo2 *info = (void *)(*match)->data;
unsigned int from, to;
char *end;
switch (c) {
case '3': /* --layer3 */
xtables_param_act(XTF_ONLY_ONCE, "length", "--layer*", *flags & F_LAYER);
info->flags &= ~XT_LENGTH_LAYER_MASK;
info->flags |= XT_LENGTH_LAYER3;
*flags |= F_LAYER;
return true;
case '4': /* --layer4 */
xtables_param_act(XTF_ONLY_ONCE, "length", "--layer*", *flags & F_LAYER);
info->flags &= ~XT_LENGTH_LAYER_MASK;
info->flags |= XT_LENGTH_LAYER4;
*flags |= F_LAYER;
return true;
case '5': /* --layer5 */
xtables_param_act(XTF_ONLY_ONCE, "length", "--layer*", *flags & F_LAYER);
info->flags &= ~XT_LENGTH_LAYER_MASK;
info->flags |= XT_LENGTH_LAYER5;
*flags |= F_LAYER;
return true;
case '7': /* --layer7 */
xtables_param_act(XTF_ONLY_ONCE, "length", "--layer*", *flags & F_LAYER);
info->flags &= ~XT_LENGTH_LAYER_MASK;
info->flags |= XT_LENGTH_LAYER7;
*flags |= F_LAYER;
return true;
case '=': /* --length */
xtables_param_act(XTF_ONLY_ONCE, "length", "--length", *flags & F_LENGTH);
if (invert)
info->flags |= XT_LENGTH_INVERT;
if (!xtables_strtoui(optarg, &end, &from, 0, ~0U))
xtables_param_act(XTF_BAD_VALUE, "length", "--length", optarg);
to = from;
if (*end == ':')
if (!xtables_strtoui(end + 1, &end, &to, 0, ~0U))
xtables_param_act(XTF_BAD_VALUE, "length",
"--length", optarg);
if (*end != '\0')
xtables_param_act(XTF_BAD_VALUE, "length", "--length", optarg);
info->min = from;
info->max = to;
*flags |= F_LENGTH;
return true;
}
return false;
}
static void length_mt_check(unsigned int flags)
{
if (!(flags & F_LENGTH))
xtables_error(PARAMETER_PROBLEM,
"length: You must specify \"--length\"");
if (!(flags & F_LAYER))
fprintf(stderr, "iptables: length match: Defaulting to "
"--layer3. Consider specifying it explicitly.\n");
}
static void length_mt_save(const void *ip, const struct xt_entry_match *match)
{
const struct xt_length_mtinfo2 *info = (const void *)match->data;
if (info->flags & XT_LENGTH_LAYER3)
printf(" --layer3 ");
else if (info->flags & XT_LENGTH_LAYER4)
printf(" --layer4 ");
else if (info->flags & XT_LENGTH_LAYER5)
printf(" --layer5 ");
else if (info->flags & XT_LENGTH_LAYER7)
printf(" --layer7 ");
if (info->flags & XT_LENGTH_INVERT)
printf(" !");
printf(" --length ");
if (info->min == info->max)
printf("%u ", (unsigned int)info->min);
else
printf("%u:%u ", (unsigned int)info->min,
(unsigned int)info->max);
}
static void length_mt_print(const void *ip, const struct xt_entry_match *match,
int numeric)
{
printf(" -m length2");
length_mt_save(ip, match);
}
static struct xtables_match length2_mt_reg = {
.version = XTABLES_VERSION,
.name = "length2",
.revision = 2,
.family = NFPROTO_UNSPEC,
.size = XT_ALIGN(sizeof(struct xt_length_mtinfo2)),
.userspacesize = XT_ALIGN(sizeof(struct xt_length_mtinfo2)),
.init = length_mt_init,
.help = length_mt_help,
.parse = length_mt_parse,
.final_check = length_mt_check,
.print = length_mt_print,
.save = length_mt_save,
.extra_opts = length_mt_opts,
};
static void _init(void)
{
xtables_register_match(&length2_mt_reg);
}
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