1 /* ebt_nat
2 *
3 * Authors:
4 * Bart De Schuymer <bdschuym@pandora.be>
5 *
6 * June, 2002
7 */
8
9 #include <stdio.h>
10 #include <stdlib.h>
11 #include <string.h>
12 #include <netinet/ether.h>
13 #include <xtables.h>
14 #include <linux/netfilter_bridge/ebt_nat.h>
15 #include "iptables/nft.h"
16 #include "iptables/nft-bridge.h"
17
18 enum {
19 O_SRC,
20 O_TARGET,
21 O_ARP,
22 };
23
24 static const struct xt_option_entry brsnat_opts[] =
25 {
26 { .name = "to-source", .id = O_SRC, .type = XTTYPE_ETHERMAC,
27 .flags = XTOPT_PUT, XTOPT_POINTER(struct ebt_nat_info, mac) },
28 { .name = "to-src", .id = O_SRC, .type = XTTYPE_ETHERMAC,
29 .flags = XTOPT_PUT, XTOPT_POINTER(struct ebt_nat_info, mac) },
30 { .name = "snat-target", .id = O_TARGET, .type = XTTYPE_STRING },
31 { .name = "snat-arp", .id = O_ARP, .type = XTTYPE_NONE },
32 XTOPT_TABLEEND,
33 };
34
brsnat_print_help(void)35 static void brsnat_print_help(void)
36 {
37 printf(
38 "snat options:\n"
39 " --to-src address : MAC address to map source to\n"
40 " --snat-target target : ACCEPT, DROP, RETURN or CONTINUE\n"
41 " --snat-arp : also change src address in arp msg\n");
42 }
43
brsnat_init(struct xt_entry_target * target)44 static void brsnat_init(struct xt_entry_target *target)
45 {
46 struct ebt_nat_info *natinfo = (struct ebt_nat_info *)target->data;
47
48 natinfo->target = EBT_ACCEPT;
49 }
50
brsnat_parse(struct xt_option_call * cb)51 static void brsnat_parse(struct xt_option_call *cb)
52 {
53 struct ebt_nat_info *natinfo = cb->data;
54 unsigned int tmp;
55
56 xtables_option_parse(cb);
57 switch (cb->entry->id) {
58 case O_TARGET:
59 if (ebt_fill_target(cb->arg, &tmp))
60 xtables_error(PARAMETER_PROBLEM,
61 "Illegal --snat-target target");
62 natinfo->target &= ~EBT_VERDICT_BITS;
63 natinfo->target |= tmp & EBT_VERDICT_BITS;
64 break;
65 case O_ARP:
66 natinfo->target ^= NAT_ARP_BIT;
67 break;
68 }
69 }
70
brsnat_final_check(struct xt_fcheck_call * fc)71 static void brsnat_final_check(struct xt_fcheck_call *fc)
72 {
73 if (!fc->xflags)
74 xtables_error(PARAMETER_PROBLEM,
75 "You must specify proper arguments");
76 }
77
brsnat_print(const void * ip,const struct xt_entry_target * target,int numeric)78 static void brsnat_print(const void *ip, const struct xt_entry_target *target, int numeric)
79 {
80 struct ebt_nat_info *natinfo = (struct ebt_nat_info *)target->data;
81
82 printf("--to-src ");
83 xtables_print_mac(natinfo->mac);
84 if (!(natinfo->target&NAT_ARP_BIT))
85 printf(" --snat-arp");
86 printf(" --snat-target %s", ebt_target_name((natinfo->target|~EBT_VERDICT_BITS)));
87 }
88
brsnat_verdict(int verdict)89 static const char* brsnat_verdict(int verdict)
90 {
91 switch (verdict) {
92 case EBT_ACCEPT: return "accept";
93 case EBT_DROP: return "drop";
94 case EBT_CONTINUE: return "continue";
95 case EBT_RETURN: return "return";
96 }
97
98 return "";
99 }
100
brsnat_xlate(struct xt_xlate * xl,const struct xt_xlate_tg_params * params)101 static int brsnat_xlate(struct xt_xlate *xl,
102 const struct xt_xlate_tg_params *params)
103 {
104 const struct ebt_nat_info *natinfo = (const void*)params->target->data;
105
106 xt_xlate_add(xl, "ether saddr set %s ",
107 ether_ntoa((struct ether_addr *)natinfo->mac));
108
109 /* NAT_ARP_BIT set -> no arp mangling, not set -> arp mangling (yes, its inverted) */
110 if (!(natinfo->target&NAT_ARP_BIT))
111 return 0;
112
113 xt_xlate_add(xl, "%s ", brsnat_verdict(natinfo->target | ~EBT_VERDICT_BITS));
114 return 1;
115 }
116
117 static struct xtables_target brsnat_target =
118 {
119 .name = "snat",
120 .version = XTABLES_VERSION,
121 .family = NFPROTO_BRIDGE,
122 .size = XT_ALIGN(sizeof(struct ebt_nat_info)),
123 .userspacesize = XT_ALIGN(sizeof(struct ebt_nat_info)),
124 .help = brsnat_print_help,
125 .init = brsnat_init,
126 .x6_parse = brsnat_parse,
127 .x6_fcheck = brsnat_final_check,
128 .print = brsnat_print,
129 .xlate = brsnat_xlate,
130 .x6_options = brsnat_opts,
131 };
132
_init(void)133 void _init(void)
134 {
135 xtables_register_target(&brsnat_target);
136 }
137