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 <getopt.h>
13 #include <netinet/ether.h>
14 #include <xtables.h>
15 #include <linux/netfilter_bridge/ebt_nat.h>
16 #include "iptables/nft.h"
17 #include "iptables/nft-bridge.h"
18
19 #define NAT_S '1'
20 #define NAT_S_TARGET '2'
21 #define NAT_S_ARP '3'
22 static const struct option brsnat_opts[] =
23 {
24 { "to-source" , required_argument, 0, NAT_S },
25 { "to-src" , required_argument, 0, NAT_S },
26 { "snat-target" , required_argument, 0, NAT_S_TARGET },
27 { "snat-arp" , no_argument, 0, NAT_S_ARP },
28 { 0 }
29 };
30
brsnat_print_help(void)31 static void brsnat_print_help(void)
32 {
33 printf(
34 "snat options:\n"
35 " --to-src address : MAC address to map source to\n"
36 " --snat-target target : ACCEPT, DROP, RETURN or CONTINUE\n"
37 " --snat-arp : also change src address in arp msg\n");
38 }
39
brsnat_init(struct xt_entry_target * target)40 static void brsnat_init(struct xt_entry_target *target)
41 {
42 struct ebt_nat_info *natinfo = (struct ebt_nat_info *)target->data;
43
44 natinfo->target = EBT_ACCEPT;
45 }
46
47 #define OPT_SNAT 0x01
48 #define OPT_SNAT_TARGET 0x02
49 #define OPT_SNAT_ARP 0x04
brsnat_parse(int c,char ** argv,int invert,unsigned int * flags,const void * entry,struct xt_entry_target ** target)50 static int brsnat_parse(int c, char **argv, int invert, unsigned int *flags,
51 const void *entry, struct xt_entry_target **target)
52 {
53 struct ebt_nat_info *natinfo = (struct ebt_nat_info *)(*target)->data;
54 struct ether_addr *addr;
55
56 switch (c) {
57 case NAT_S:
58 EBT_CHECK_OPTION(flags, OPT_SNAT);
59 if (!(addr = ether_aton(optarg)))
60 xtables_error(PARAMETER_PROBLEM, "Problem with specified --to-source mac");
61 memcpy(natinfo->mac, addr, ETH_ALEN);
62 break;
63 case NAT_S_TARGET:
64 { unsigned int tmp;
65 EBT_CHECK_OPTION(flags, OPT_SNAT_TARGET);
66 if (ebt_fill_target(optarg, &tmp))
67 xtables_error(PARAMETER_PROBLEM, "Illegal --snat-target target");
68 natinfo->target = (natinfo->target & ~EBT_VERDICT_BITS) | (tmp & EBT_VERDICT_BITS);
69 }
70 break;
71 case NAT_S_ARP:
72 EBT_CHECK_OPTION(flags, OPT_SNAT_ARP);
73 natinfo->target ^= NAT_ARP_BIT;
74 break;
75 default:
76 return 0;
77 }
78 return 1;
79 }
80
brsnat_final_check(unsigned int flags)81 static void brsnat_final_check(unsigned int flags)
82 {
83 if (!flags)
84 xtables_error(PARAMETER_PROBLEM,
85 "You must specify proper arguments");
86 }
87
brsnat_print(const void * ip,const struct xt_entry_target * target,int numeric)88 static void brsnat_print(const void *ip, const struct xt_entry_target *target, int numeric)
89 {
90 struct ebt_nat_info *natinfo = (struct ebt_nat_info *)target->data;
91
92 printf("--to-src ");
93 xtables_print_mac(natinfo->mac);
94 if (!(natinfo->target&NAT_ARP_BIT))
95 printf(" --snat-arp");
96 printf(" --snat-target %s", ebt_target_name((natinfo->target|~EBT_VERDICT_BITS)));
97 }
98
brsnat_verdict(int verdict)99 static const char* brsnat_verdict(int verdict)
100 {
101 switch (verdict) {
102 case EBT_ACCEPT: return "accept";
103 case EBT_DROP: return "drop";
104 case EBT_CONTINUE: return "continue";
105 case EBT_RETURN: return "return";
106 }
107
108 return "";
109 }
110
brsnat_xlate(struct xt_xlate * xl,const struct xt_xlate_tg_params * params)111 static int brsnat_xlate(struct xt_xlate *xl,
112 const struct xt_xlate_tg_params *params)
113 {
114 const struct ebt_nat_info *natinfo = (const void*)params->target->data;
115
116 xt_xlate_add(xl, "ether saddr set %s ",
117 ether_ntoa((struct ether_addr *)natinfo->mac));
118
119 /* NAT_ARP_BIT set -> no arp mangling, not set -> arp mangling (yes, its inverted) */
120 if (!(natinfo->target&NAT_ARP_BIT))
121 return 0;
122
123 xt_xlate_add(xl, "%s ", brsnat_verdict(natinfo->target | ~EBT_VERDICT_BITS));
124 return 1;
125 }
126
127 static struct xtables_target brsnat_target =
128 {
129 .name = "snat",
130 .version = XTABLES_VERSION,
131 .family = NFPROTO_BRIDGE,
132 .size = XT_ALIGN(sizeof(struct ebt_nat_info)),
133 .userspacesize = XT_ALIGN(sizeof(struct ebt_nat_info)),
134 .help = brsnat_print_help,
135 .init = brsnat_init,
136 .parse = brsnat_parse,
137 .final_check = brsnat_final_check,
138 .print = brsnat_print,
139 .xlate = brsnat_xlate,
140 .extra_opts = brsnat_opts,
141 };
142
_init(void)143 void _init(void)
144 {
145 xtables_register_target(&brsnat_target);
146 }
147