Sven Schnelle | aef4c1e | 2008-01-20 13:45:16 +0000 | [diff] [blame] | 1 | /* |
| 2 | * Shared library add-on to iptables to add TCPOPTSTRIP target support. |
| 3 | * Copyright (c) 2007 Sven Schnelle <svens@bitebene.org> |
| 4 | * Copyright © CC Computer Consultants GmbH, 2007 |
| 5 | * Jan Engelhardt <jengelh@computergmbh.de> |
| 6 | */ |
| 7 | #include <getopt.h> |
| 8 | #include <stdbool.h> |
| 9 | #include <stdio.h> |
| 10 | #include <string.h> |
| 11 | #include <stdlib.h> |
| 12 | #include <xtables.h> |
Jan Engelhardt | ef18e81 | 2008-08-04 12:47:48 +0200 | [diff] [blame] | 13 | #include <netinet/tcp.h> |
Sven Schnelle | aef4c1e | 2008-01-20 13:45:16 +0000 | [diff] [blame] | 14 | #include <linux/netfilter/x_tables.h> |
| 15 | #include <linux/netfilter/xt_TCPOPTSTRIP.h> |
| 16 | #ifndef TCPOPT_MD5SIG |
| 17 | # define TCPOPT_MD5SIG 19 |
| 18 | #endif |
| 19 | |
| 20 | enum { |
| 21 | FLAG_STRIP = 1 << 0, |
| 22 | }; |
| 23 | |
| 24 | struct tcp_optionmap { |
| 25 | const char *name, *desc; |
Jan Engelhardt | 7a236f4 | 2008-03-03 12:30:41 +0100 | [diff] [blame] | 26 | const unsigned int option; |
Sven Schnelle | aef4c1e | 2008-01-20 13:45:16 +0000 | [diff] [blame] | 27 | }; |
| 28 | |
| 29 | static const struct option tcpoptstrip_tg_opts[] = { |
| 30 | {.name = "strip-options", .has_arg = true, .val = 's'}, |
Max Kellermann | 9ee386a | 2008-01-29 13:48:05 +0000 | [diff] [blame] | 31 | { .name = NULL } |
Sven Schnelle | aef4c1e | 2008-01-20 13:45:16 +0000 | [diff] [blame] | 32 | }; |
| 33 | |
| 34 | static const struct tcp_optionmap tcp_optionmap[] = { |
| 35 | {"wscale", "Window scale", TCPOPT_WINDOW}, |
| 36 | {"mss", "Maximum Segment Size", TCPOPT_MAXSEG}, |
| 37 | {"sack-permitted", "SACK permitted", TCPOPT_SACK_PERMITTED}, |
| 38 | {"sack", "Selective ACK", TCPOPT_SACK}, |
| 39 | {"timestamp", "Timestamp", TCPOPT_TIMESTAMP}, |
| 40 | {"md5", "MD5 signature", TCPOPT_MD5SIG}, |
Max Kellermann | 9ee386a | 2008-01-29 13:48:05 +0000 | [diff] [blame] | 41 | { .name = NULL } |
Sven Schnelle | aef4c1e | 2008-01-20 13:45:16 +0000 | [diff] [blame] | 42 | }; |
| 43 | |
| 44 | static void tcpoptstrip_tg_help(void) |
| 45 | { |
| 46 | const struct tcp_optionmap *w; |
| 47 | |
| 48 | printf( |
| 49 | "TCPOPTSTRIP target options:\n" |
| 50 | " --strip-options value strip specified TCP options denoted by value\n" |
| 51 | " (separated by comma) from TCP header\n" |
| 52 | " Instead of the numeric value, you can also use the following names:\n" |
| 53 | ); |
| 54 | |
| 55 | for (w = tcp_optionmap; w->name != NULL; ++w) |
| 56 | printf(" %-14s strip \"%s\" option\n", w->name, w->desc); |
| 57 | } |
| 58 | |
| 59 | static void tcpoptstrip_tg_init(struct xt_entry_target *t) |
| 60 | { |
| 61 | struct xt_tcpoptstrip_target_info *info = (void *)t->data; |
| 62 | |
| 63 | /* strictly necessary? play safe for now. */ |
| 64 | memset(info->strip_bmap, 0, sizeof(info->strip_bmap)); |
| 65 | } |
| 66 | |
| 67 | static void parse_list(struct xt_tcpoptstrip_target_info *info, char *arg) |
| 68 | { |
| 69 | unsigned int option; |
| 70 | char *p; |
| 71 | int i; |
| 72 | |
| 73 | while (true) { |
| 74 | p = strchr(arg, ','); |
| 75 | if (p != NULL) |
| 76 | *p = '\0'; |
| 77 | |
| 78 | option = 0; |
| 79 | for (i = 0; tcp_optionmap[i].name != NULL; ++i) |
| 80 | if (strcmp(tcp_optionmap[i].name, arg) == 0) { |
| 81 | option = tcp_optionmap[i].option; |
| 82 | break; |
| 83 | } |
| 84 | |
Jan Engelhardt | 5f2922c | 2009-01-27 18:43:01 +0100 | [diff] [blame] | 85 | if (option == 0 && |
| 86 | !xtables_strtoui(arg, NULL, &option, 0, UINT8_MAX)) |
Sven Schnelle | aef4c1e | 2008-01-20 13:45:16 +0000 | [diff] [blame] | 87 | exit_error(PARAMETER_PROBLEM, |
| 88 | "Bad TCP option value \"%s\"", arg); |
| 89 | |
| 90 | if (option < 2) |
| 91 | exit_error(PARAMETER_PROBLEM, |
| 92 | "Option value may not be 0 or 1"); |
| 93 | |
| 94 | if (tcpoptstrip_test_bit(info->strip_bmap, option)) |
| 95 | exit_error(PARAMETER_PROBLEM, |
| 96 | "Option \"%s\" already specified", arg); |
| 97 | |
| 98 | tcpoptstrip_set_bit(info->strip_bmap, option); |
| 99 | if (p == NULL) |
| 100 | break; |
| 101 | arg = p + 1; |
| 102 | } |
| 103 | } |
| 104 | |
| 105 | static int tcpoptstrip_tg_parse(int c, char **argv, int invert, |
| 106 | unsigned int *flags, const void *entry, |
| 107 | struct xt_entry_target **target) |
| 108 | { |
| 109 | struct xt_tcpoptstrip_target_info *info = (void *)(*target)->data; |
| 110 | |
| 111 | switch (c) { |
| 112 | case 's': |
| 113 | if (*flags & FLAG_STRIP) |
| 114 | exit_error(PARAMETER_PROBLEM, |
| 115 | "You can specify --strip-options only once"); |
| 116 | parse_list(info, optarg); |
| 117 | *flags |= FLAG_STRIP; |
| 118 | return true; |
| 119 | } |
| 120 | |
| 121 | return false; |
| 122 | } |
| 123 | |
| 124 | static void tcpoptstrip_tg_check(unsigned int flags) |
| 125 | { |
| 126 | if (flags == 0) |
| 127 | exit_error(PARAMETER_PROBLEM, |
| 128 | "TCPOPTSTRIP: --strip-options parameter required"); |
| 129 | } |
| 130 | |
| 131 | static void |
| 132 | tcpoptstrip_print_list(const struct xt_tcpoptstrip_target_info *info, |
| 133 | bool numeric) |
| 134 | { |
| 135 | unsigned int i, j; |
| 136 | const char *name; |
| 137 | bool first = true; |
| 138 | |
| 139 | for (i = 0; i < 256; ++i) { |
| 140 | if (!tcpoptstrip_test_bit(info->strip_bmap, i)) |
| 141 | continue; |
| 142 | if (!first) |
| 143 | printf(","); |
| 144 | |
| 145 | first = false; |
| 146 | name = NULL; |
| 147 | if (!numeric) |
| 148 | for (j = 0; tcp_optionmap[j].name != NULL; ++j) |
| 149 | if (tcp_optionmap[j].option == i) |
| 150 | name = tcp_optionmap[j].name; |
| 151 | |
| 152 | if (name != NULL) |
| 153 | printf("%s", name); |
| 154 | else |
| 155 | printf("%u", i); |
| 156 | } |
| 157 | } |
| 158 | |
| 159 | static void |
| 160 | tcpoptstrip_tg_print(const void *ip, const struct xt_entry_target *target, |
| 161 | int numeric) |
| 162 | { |
| 163 | const struct xt_tcpoptstrip_target_info *info = |
| 164 | (const void *)target->data; |
| 165 | |
| 166 | printf("TCPOPTSTRIP options "); |
| 167 | tcpoptstrip_print_list(info, numeric); |
| 168 | } |
| 169 | |
| 170 | static void |
| 171 | tcpoptstrip_tg_save(const void *ip, const struct xt_entry_target *target) |
| 172 | { |
| 173 | const struct xt_tcpoptstrip_target_info *info = |
| 174 | (const void *)target->data; |
| 175 | |
| 176 | printf("--strip-options "); |
| 177 | tcpoptstrip_print_list(info, true); |
| 178 | } |
| 179 | |
| 180 | static struct xtables_target tcpoptstrip_tg_reg = { |
Jan Engelhardt | 8b7c64d | 2008-04-15 11:48:25 +0200 | [diff] [blame] | 181 | .version = XTABLES_VERSION, |
Sven Schnelle | aef4c1e | 2008-01-20 13:45:16 +0000 | [diff] [blame] | 182 | .name = "TCPOPTSTRIP", |
Jan Engelhardt | 03d9948 | 2008-11-18 12:27:54 +0100 | [diff] [blame] | 183 | .family = NFPROTO_IPV4, |
Sven Schnelle | aef4c1e | 2008-01-20 13:45:16 +0000 | [diff] [blame] | 184 | .size = XT_ALIGN(sizeof(struct xt_tcpoptstrip_target_info)), |
| 185 | .userspacesize = XT_ALIGN(sizeof(struct xt_tcpoptstrip_target_info)), |
| 186 | .help = tcpoptstrip_tg_help, |
| 187 | .init = tcpoptstrip_tg_init, |
| 188 | .parse = tcpoptstrip_tg_parse, |
| 189 | .final_check = tcpoptstrip_tg_check, |
| 190 | .print = tcpoptstrip_tg_print, |
| 191 | .save = tcpoptstrip_tg_save, |
| 192 | .extra_opts = tcpoptstrip_tg_opts, |
| 193 | }; |
| 194 | |
| 195 | static struct xtables_target tcpoptstrip_tg6_reg = { |
Jan Engelhardt | 8b7c64d | 2008-04-15 11:48:25 +0200 | [diff] [blame] | 196 | .version = XTABLES_VERSION, |
Sven Schnelle | aef4c1e | 2008-01-20 13:45:16 +0000 | [diff] [blame] | 197 | .name = "TCPOPTSTRIP", |
Jan Engelhardt | 03d9948 | 2008-11-18 12:27:54 +0100 | [diff] [blame] | 198 | .family = NFPROTO_IPV6, |
Sven Schnelle | aef4c1e | 2008-01-20 13:45:16 +0000 | [diff] [blame] | 199 | .size = XT_ALIGN(sizeof(struct xt_tcpoptstrip_target_info)), |
| 200 | .userspacesize = XT_ALIGN(sizeof(struct xt_tcpoptstrip_target_info)), |
| 201 | .help = tcpoptstrip_tg_help, |
| 202 | .init = tcpoptstrip_tg_init, |
| 203 | .parse = tcpoptstrip_tg_parse, |
| 204 | .final_check = tcpoptstrip_tg_check, |
| 205 | .print = tcpoptstrip_tg_print, |
| 206 | .save = tcpoptstrip_tg_save, |
| 207 | .extra_opts = tcpoptstrip_tg_opts, |
| 208 | }; |
| 209 | |
| 210 | void _init(void) |
| 211 | { |
| 212 | xtables_register_target(&tcpoptstrip_tg_reg); |
| 213 | xtables_register_target(&tcpoptstrip_tg6_reg); |
| 214 | } |