diff options
Diffstat (limited to 'extensions/libxt_NAT.c')
| -rw-r--r-- | extensions/libxt_NAT.c | 646 |
1 files changed, 646 insertions, 0 deletions
diff --git a/extensions/libxt_NAT.c b/extensions/libxt_NAT.c new file mode 100644 index 00000000..2a634398 --- /dev/null +++ b/extensions/libxt_NAT.c @@ -0,0 +1,646 @@ +/* + * Copyright (c) 2011 Patrick McHardy <kaber@trash.net> + * + * Based on Rusty Russell's IPv4 DNAT target. Development of IPv6 NAT + * funded by Astaro. + */ + +#include <stdio.h> +#include <netdb.h> +#include <string.h> +#include <stdlib.h> +#include <xtables.h> +#include <iptables.h> /* get_kernel_version */ +#include <limits.h> /* INT_MAX in ip_tables.h */ +#include <arpa/inet.h> +#include <linux/netfilter_ipv4/ip_tables.h> +#include <linux/netfilter_ipv6/ip6_tables.h> +#include <linux/netfilter/nf_nat.h> + +#define TO_IPV4_MRC(ptr) ((const struct nf_nat_ipv4_multi_range_compat *)(ptr)) +#define RANGE2_INIT_FROM_IPV4_MRC(ptr) { \ + .flags = TO_IPV4_MRC(ptr)->range[0].flags, \ + .min_addr.ip = TO_IPV4_MRC(ptr)->range[0].min_ip, \ + .max_addr.ip = TO_IPV4_MRC(ptr)->range[0].max_ip, \ + .min_proto = TO_IPV4_MRC(ptr)->range[0].min, \ + .max_proto = TO_IPV4_MRC(ptr)->range[0].max, \ +}; +#define TO_NF_NAT_RANGE(ptr) ((const struct nf_nat_range *)(ptr)) +#define RANGE2_INIT_FROM_RANGE(ptr) { \ + .flags = TO_NF_NAT_RANGE(ptr)->flags, \ + .min_addr = TO_NF_NAT_RANGE(ptr)->min_addr, \ + .max_addr = TO_NF_NAT_RANGE(ptr)->max_addr, \ + .min_proto = TO_NF_NAT_RANGE(ptr)->min_proto, \ + .max_proto = TO_NF_NAT_RANGE(ptr)->max_proto, \ +}; + +enum { + O_TO_DEST = 0, + O_TO_SRC, + O_TO_PORTS, + O_RANDOM, + O_RANDOM_FULLY, + O_PERSISTENT, +}; + +static void SNAT_help(void) +{ + printf( +"SNAT target options:\n" +" --to-source [<ipaddr>[-<ipaddr>]][:port[-port]]\n" +" Address to map source to.\n" +"[--random] [--random-fully] [--persistent]\n"); +} + +static void MASQUERADE_help(void) +{ + printf( +"MASQUERADE target options:\n" +" --to-ports <port>[-<port>]\n" +" Port (range) to map to.\n" +" --random\n" +" Randomize source port.\n" +" --random-fully\n" +" Fully randomize source port.\n"); +} + +static void DNAT_help(void) +{ + printf( +"DNAT target options:\n" +" --to-destination [<ipaddr>[-<ipaddr>]][:port[-port]]\n" +" Address to map destination to.\n" +"[--random] [--persistent]\n"); +} + +static void DNAT_help_v2(void) +{ + printf( +"DNAT target options:\n" +" --to-destination [<ipaddr>[-<ipaddr>]][:port[-port[/port]]]\n" +" Address to map destination to.\n" +"[--random] [--persistent]\n"); +} + +static void REDIRECT_help(void) +{ + printf( +"REDIRECT target options:\n" +" --to-ports <port>[-<port>]\n" +" Port (range) to map to.\n" +" [--random]\n"); +} + +static const struct xt_option_entry SNAT_opts[] = { + {.name = "to-source", .id = O_TO_SRC, .type = XTTYPE_STRING, + .flags = XTOPT_MAND}, + {.name = "random", .id = O_RANDOM, .type = XTTYPE_NONE}, + {.name = "random-fully", .id = O_RANDOM_FULLY, .type = XTTYPE_NONE}, + {.name = "persistent", .id = O_PERSISTENT, .type = XTTYPE_NONE}, + XTOPT_TABLEEND, +}; + +static const struct xt_option_entry MASQUERADE_opts[] = { + {.name = "to-ports", .id = O_TO_PORTS, .type = XTTYPE_STRING}, + {.name = "random", .id = O_RANDOM, .type = XTTYPE_NONE}, + {.name = "random-fully", .id = O_RANDOM_FULLY, .type = XTTYPE_NONE}, + XTOPT_TABLEEND, +}; + +static const struct xt_option_entry DNAT_opts[] = { + {.name = "to-destination", .id = O_TO_DEST, .type = XTTYPE_STRING, + .flags = XTOPT_MAND}, + {.name = "random", .id = O_RANDOM, .type = XTTYPE_NONE}, + {.name = "persistent", .id = O_PERSISTENT, .type = XTTYPE_NONE}, + XTOPT_TABLEEND, +}; + +static const struct xt_option_entry REDIRECT_opts[] = { + {.name = "to-ports", .id = O_TO_PORTS, .type = XTTYPE_STRING}, + {.name = "random", .id = O_RANDOM, .type = XTTYPE_NONE}, + XTOPT_TABLEEND, +}; + +/* Parses ports */ +static void +parse_ports(const char *arg, bool portok, struct nf_nat_range2 *range) +{ + unsigned int port, maxport, baseport; + char *end = NULL; + + if (!portok) + xtables_error(PARAMETER_PROBLEM, + "Need TCP, UDP, SCTP or DCCP with port specification"); + + range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED; + + if (!xtables_strtoui(arg, &end, &port, 0, UINT16_MAX)) { + port = xtables_service_to_port(arg, NULL); + if (port == (unsigned)-1) + xtables_error(PARAMETER_PROBLEM, + "Port `%s' not valid", arg); + end = ""; + } + + switch (*end) { + case '\0': + range->min_proto.tcp.port + = range->max_proto.tcp.port + = htons(port); + return; + case '-': + arg = end + 1; + break; + case ':': + xtables_error(PARAMETER_PROBLEM, + "Invalid port:port syntax - use dash"); + default: + xtables_error(PARAMETER_PROBLEM, + "Garbage after port value: `%s'", end); + } + + /* it is a range, don't allow service names here */ + if (!xtables_strtoui(arg, &end, &maxport, 0, UINT16_MAX)) + xtables_error(PARAMETER_PROBLEM, "Port `%s' not valid", arg); + + if (maxport < port) + /* People are stupid. */ + xtables_error(PARAMETER_PROBLEM, + "Port range `%s' funky", arg); + + range->min_proto.tcp.port = htons(port); + range->max_proto.tcp.port = htons(maxport); + + switch (*end) { + case '\0': + return; + case '/': + arg = end + 1; + break; + default: + xtables_error(PARAMETER_PROBLEM, + "Garbage after port range: `%s'", end); + } + + if (!xtables_strtoui(arg, &end, &baseport, 1, UINT16_MAX)) { + baseport = xtables_service_to_port(arg, NULL); + if (baseport == (unsigned)-1) + xtables_error(PARAMETER_PROBLEM, + "Port `%s' not valid", arg); + } + + range->flags |= NF_NAT_RANGE_PROTO_OFFSET; + range->base_proto.tcp.port = htons(baseport); +} + +/* Ranges expected in network order. */ +static void +parse_to(const char *orig_arg, bool portok, + struct nf_nat_range2 *range, int family) +{ + char *arg, *start, *end, *colon, *dash; + + arg = xtables_strdup(orig_arg); + start = strchr(arg, '['); + if (!start) { + start = arg; + /* Lets assume one colon is port information. + * Otherwise its an IPv6 address */ + colon = strchr(arg, ':'); + if (colon && strchr(colon + 1, ':')) + colon = NULL; + } else { + start++; + end = strchr(start, ']'); + if (end == NULL || family == AF_INET) + xtables_error(PARAMETER_PROBLEM, + "Invalid address format"); + + *end = '\0'; + colon = strchr(end + 1, ':'); + } + + if (colon) { + parse_ports(colon + 1, portok, range); + + /* Starts with colon or [] colon? No IP info...*/ + if (colon == arg || colon == arg + 2) { + free(arg); + return; + } + *colon = '\0'; + } + + range->flags |= NF_NAT_RANGE_MAP_IPS; + dash = strchr(start, '-'); + if (colon && dash && dash > colon) + dash = NULL; + + if (dash) + *dash = '\0'; + + if (!inet_pton(family, start, &range->min_addr)) + xtables_error(PARAMETER_PROBLEM, + "Bad IP address \"%s\"", start); + if (dash) { + if (!inet_pton(family, dash + 1, &range->max_addr)) + xtables_error(PARAMETER_PROBLEM, + "Bad IP address \"%s\"", dash + 1); + } else { + range->max_addr = range->min_addr; + } + free(arg); + return; +} + +static void __NAT_parse(struct xt_option_call *cb, __u16 proto, + struct nf_nat_range2 *range, int family) +{ + bool portok = proto == IPPROTO_TCP || + proto == IPPROTO_UDP || + proto == IPPROTO_SCTP || + proto == IPPROTO_DCCP || + proto == IPPROTO_ICMP; + + xtables_option_parse(cb); + switch (cb->entry->id) { + case O_TO_DEST: + case O_TO_SRC: + parse_to(cb->arg, portok, range, family); + break; + case O_TO_PORTS: + parse_ports(cb->arg, portok, range); + break; + case O_PERSISTENT: + range->flags |= NF_NAT_RANGE_PERSISTENT; + break; + case O_RANDOM: + range->flags |= NF_NAT_RANGE_PROTO_RANDOM; + break; + case O_RANDOM_FULLY: + range->flags |= NF_NAT_RANGE_PROTO_RANDOM_FULLY; + break; + } +} + +static void NAT_parse(struct xt_option_call *cb) +{ + struct nf_nat_ipv4_multi_range_compat *mr = (void *)cb->data; + const struct ipt_entry *entry = cb->xt_entry; + struct nf_nat_range2 range = {}; + + __NAT_parse(cb, entry->ip.proto, &range, AF_INET); + + switch (cb->entry->id) { + case O_TO_DEST: + case O_TO_SRC: + mr->range->min_ip = range.min_addr.ip; + mr->range->max_ip = range.max_addr.ip; + /* fall through */ + case O_TO_PORTS: + mr->range->min = range.min_proto; + mr->range->max = range.max_proto; + /* fall through */ + case O_PERSISTENT: + case O_RANDOM: + case O_RANDOM_FULLY: + mr->range->flags |= range.flags; + break; + } +} + +static void NAT_parse6(struct xt_option_call *cb) +{ + struct nf_nat_range2 range = RANGE2_INIT_FROM_RANGE(cb->data); + struct nf_nat_range *range_v1 = (void *)cb->data; + const struct ip6t_entry *entry = cb->xt_entry; + + __NAT_parse(cb, entry->ipv6.proto, &range, AF_INET6); + memcpy(range_v1, &range, sizeof(*range_v1)); +} + +static void DNAT_parse_v2(struct xt_option_call *cb) +{ + const struct ipt_entry *entry = cb->xt_entry; + + __NAT_parse(cb, entry->ip.proto, cb->data, AF_INET); +} + +static void DNAT_parse6_v2(struct xt_option_call *cb) +{ + const struct ip6t_entry *entry = cb->xt_entry; + + __NAT_parse(cb, entry->ipv6.proto, cb->data, AF_INET6); +} + +static void SNAT_fcheck(struct xt_fcheck_call *cb) +{ + struct nf_nat_ipv4_multi_range_compat *mr = cb->data; + + mr->rangesize = 1; +} + +static void DNAT_fcheck(struct xt_fcheck_call *cb) +{ + struct nf_nat_ipv4_multi_range_compat *mr = cb->data; + + mr->rangesize = 1; + + if (mr->range[0].flags & NF_NAT_RANGE_PROTO_OFFSET) + xtables_error(PARAMETER_PROBLEM, + "Shifted portmap ranges not supported with this kernel"); +} + +static void DNAT_fcheck6(struct xt_fcheck_call *cb) +{ + struct nf_nat_range *range = (void *)cb->data; + + if (range->flags & NF_NAT_RANGE_PROTO_OFFSET) + xtables_error(PARAMETER_PROBLEM, + "Shifted portmap ranges not supported with this kernel"); +} + +static char *sprint_range(const struct nf_nat_range2 *r, int family) +{ + bool brackets = family == AF_INET6 && + r->flags & NF_NAT_RANGE_PROTO_SPECIFIED; + static char buf[INET6_ADDRSTRLEN * 2 + 3 + 6 * 3]; + + buf[0] = '\0'; + + if (r->flags & NF_NAT_RANGE_MAP_IPS) { + if (brackets) + strcat(buf, "["); + inet_ntop(family, &r->min_addr, + buf + strlen(buf), INET6_ADDRSTRLEN); + if (memcmp(&r->min_addr, &r->max_addr, sizeof(r->min_addr))) { + strcat(buf, "-"); + inet_ntop(family, &r->max_addr, + buf + strlen(buf), INET6_ADDRSTRLEN); + } + if (brackets) + strcat(buf, "]"); + } + if (r->flags & NF_NAT_RANGE_PROTO_SPECIFIED) { + sprintf(buf + strlen(buf), ":%hu", + ntohs(r->min_proto.tcp.port)); + if (r->max_proto.tcp.port != r->min_proto.tcp.port) + sprintf(buf + strlen(buf), "-%hu", + ntohs(r->max_proto.tcp.port)); + if (r->flags & NF_NAT_RANGE_PROTO_OFFSET) + sprintf(buf + strlen(buf), "/%hu", + ntohs(r->base_proto.tcp.port)); + } + return buf; +} + +static void __NAT_print(const struct nf_nat_range2 *r, int family, + const char *rangeopt, const char *flag_pfx, + bool skip_colon) +{ + char *range_str = sprint_range(r, family); + + if (strlen(range_str)) { + if (range_str[0] == ':' && skip_colon) + range_str++; + printf(" %s%s", rangeopt, range_str); + } + if (r->flags & NF_NAT_RANGE_PROTO_RANDOM) + printf(" %srandom", flag_pfx); + if (r->flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY) + printf(" %srandom-fully", flag_pfx); + if (r->flags & NF_NAT_RANGE_PERSISTENT) + printf(" %spersistent", flag_pfx); +} + +static int +__NAT_xlate(struct xt_xlate *xl, const struct nf_nat_range2 *r, + int family, const char *tgt) +{ + char *range_str = sprint_range(r, family); + const char *sep = " "; + + /* shifted portmap ranges are not supported by nftables */ + if (r->flags & NF_NAT_RANGE_PROTO_OFFSET) + return 0; + + xt_xlate_add(xl, "%s", tgt); + if (strlen(range_str)) + xt_xlate_add(xl, " to %s", range_str); + if (r->flags & NF_NAT_RANGE_PROTO_RANDOM) { + xt_xlate_add(xl, "%srandom", sep); + sep = ","; + } + if (r->flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY) { + xt_xlate_add(xl, "%sfully-random", sep); + sep = ","; + } + if (r->flags & NF_NAT_RANGE_PERSISTENT) { + xt_xlate_add(xl, "%spersistent", sep); + sep = ","; + } + return 1; +} + +#define PSX_GEN(name, converter, family, \ + print_rangeopt, save_rangeopt, skip_colon, xlate) \ +static void name##_print(const void *ip, const struct xt_entry_target *target, \ + int numeric) \ +{ \ + struct nf_nat_range2 range = converter(target->data); \ + \ + __NAT_print(&range, family, print_rangeopt, "", skip_colon); \ +} \ +static void name##_save(const void *ip, const struct xt_entry_target *target) \ +{ \ + struct nf_nat_range2 range = converter(target->data); \ + \ + __NAT_print(&range, family, save_rangeopt, "--", skip_colon); \ +} \ +static int name##_xlate(struct xt_xlate *xl, \ + const struct xt_xlate_tg_params *params) \ +{ \ + struct nf_nat_range2 range = converter(params->target->data); \ + \ + return __NAT_xlate(xl, &range, family, xlate); \ +} + +PSX_GEN(DNAT, RANGE2_INIT_FROM_IPV4_MRC, \ + AF_INET, "to:", "--to-destination ", false, "dnat") + +PSX_GEN(DNATv2, *(struct nf_nat_range2 *), \ + AF_INET, "to:", "--to-destination ", false, "dnat") + +PSX_GEN(DNAT6, RANGE2_INIT_FROM_RANGE, \ + AF_INET6, "to:", "--to-destination ", false, "dnat") + +PSX_GEN(DNAT6v2, *(struct nf_nat_range2 *), \ + AF_INET6, "to:", "--to-destination ", false, "dnat") + +PSX_GEN(REDIRECT, RANGE2_INIT_FROM_IPV4_MRC, \ + AF_INET, "redir ports ", "--to-ports ", true, "redirect") + +PSX_GEN(REDIRECT6, RANGE2_INIT_FROM_RANGE, \ + AF_INET6, "redir ports ", "--to-ports ", true, "redirect") + +PSX_GEN(SNAT, RANGE2_INIT_FROM_IPV4_MRC, \ + AF_INET, "to:", "--to-source ", false, "snat") + +PSX_GEN(SNAT6, RANGE2_INIT_FROM_RANGE, \ + AF_INET6, "to:", "--to-source ", false, "snat") + +PSX_GEN(MASQUERADE, RANGE2_INIT_FROM_IPV4_MRC, \ + AF_INET, "masq ports: ", "--to-ports ", true, "masquerade") + +PSX_GEN(MASQUERADE6, RANGE2_INIT_FROM_RANGE, \ + AF_INET6, "masq ports: ", "--to-ports ", true, "masquerade") + +static struct xtables_target nat_tg_reg[] = { + { + .name = "SNAT", + .version = XTABLES_VERSION, + .family = NFPROTO_IPV4, + .size = XT_ALIGN(sizeof(struct nf_nat_ipv4_multi_range_compat)), + .userspacesize = XT_ALIGN(sizeof(struct nf_nat_ipv4_multi_range_compat)), + .help = SNAT_help, + .x6_parse = NAT_parse, + .x6_fcheck = SNAT_fcheck, + .print = SNAT_print, + .save = SNAT_save, + .x6_options = SNAT_opts, + .xlate = SNAT_xlate, + }, + { + .name = "DNAT", + .version = XTABLES_VERSION, + .family = NFPROTO_IPV4, + .revision = 0, + .size = XT_ALIGN(sizeof(struct nf_nat_ipv4_multi_range_compat)), + .userspacesize = XT_ALIGN(sizeof(struct nf_nat_ipv4_multi_range_compat)), + .help = DNAT_help, + .print = DNAT_print, + .save = DNAT_save, + .x6_parse = NAT_parse, + .x6_fcheck = DNAT_fcheck, + .x6_options = DNAT_opts, + .xlate = DNAT_xlate, + }, + { + .name = "MASQUERADE", + .version = XTABLES_VERSION, + .family = NFPROTO_IPV4, + .size = XT_ALIGN(sizeof(struct nf_nat_ipv4_multi_range_compat)), + .userspacesize = XT_ALIGN(sizeof(struct nf_nat_ipv4_multi_range_compat)), + .help = MASQUERADE_help, + .x6_parse = NAT_parse, + .x6_fcheck = SNAT_fcheck, + .print = MASQUERADE_print, + .save = MASQUERADE_save, + .x6_options = MASQUERADE_opts, + .xlate = MASQUERADE_xlate, + }, + { + .name = "MASQUERADE", + .version = XTABLES_VERSION, + .family = NFPROTO_IPV6, + .size = XT_ALIGN(sizeof(struct nf_nat_range)), + .userspacesize = XT_ALIGN(sizeof(struct nf_nat_range)), + .help = MASQUERADE_help, + .x6_parse = NAT_parse6, + .print = MASQUERADE6_print, + .save = MASQUERADE6_save, + .x6_options = MASQUERADE_opts, + .xlate = MASQUERADE6_xlate, + }, + { + .name = "REDIRECT", + .version = XTABLES_VERSION, + .family = NFPROTO_IPV4, + .revision = 0, + .size = XT_ALIGN(sizeof(struct nf_nat_ipv4_multi_range_compat)), + .userspacesize = XT_ALIGN(sizeof(struct nf_nat_ipv4_multi_range_compat)), + .help = REDIRECT_help, + .print = REDIRECT_print, + .save = REDIRECT_save, + .x6_parse = NAT_parse, + .x6_fcheck = DNAT_fcheck, + .x6_options = REDIRECT_opts, + .xlate = REDIRECT_xlate, + }, + { + .name = "SNAT", + .version = XTABLES_VERSION, + .family = NFPROTO_IPV6, + .revision = 1, + .size = XT_ALIGN(sizeof(struct nf_nat_range)), + .userspacesize = XT_ALIGN(sizeof(struct nf_nat_range)), + .help = SNAT_help, + .x6_parse = NAT_parse6, + .print = SNAT6_print, + .save = SNAT6_save, + .x6_options = SNAT_opts, + .xlate = SNAT6_xlate, + }, + { + .name = "DNAT", + .version = XTABLES_VERSION, + .family = NFPROTO_IPV6, + .revision = 1, + .size = XT_ALIGN(sizeof(struct nf_nat_range)), + .userspacesize = XT_ALIGN(sizeof(struct nf_nat_range)), + .help = DNAT_help, + .print = DNAT6_print, + .save = DNAT6_save, + .x6_parse = NAT_parse6, + .x6_fcheck = DNAT_fcheck6, + .x6_options = DNAT_opts, + .xlate = DNAT6_xlate, + }, + { + .name = "REDIRECT", + .version = XTABLES_VERSION, + .family = NFPROTO_IPV6, + .size = XT_ALIGN(sizeof(struct nf_nat_range)), + .userspacesize = XT_ALIGN(sizeof(struct nf_nat_range)), + .help = REDIRECT_help, + .print = REDIRECT6_print, + .save = REDIRECT6_save, + .x6_parse = NAT_parse6, + .x6_fcheck = DNAT_fcheck6, + .x6_options = REDIRECT_opts, + .xlate = REDIRECT6_xlate, + }, + { + .name = "DNAT", + .version = XTABLES_VERSION, + .family = NFPROTO_IPV4, + .revision = 2, + .size = XT_ALIGN(sizeof(struct nf_nat_range2)), + .userspacesize = XT_ALIGN(sizeof(struct nf_nat_range2)), + .help = DNAT_help_v2, + .print = DNATv2_print, + .save = DNATv2_save, + .x6_parse = DNAT_parse_v2, + .x6_options = DNAT_opts, + .xlate = DNATv2_xlate, + }, + { + .name = "DNAT", + .version = XTABLES_VERSION, + .family = NFPROTO_IPV6, + .revision = 2, + .size = XT_ALIGN(sizeof(struct nf_nat_range2)), + .userspacesize = XT_ALIGN(sizeof(struct nf_nat_range2)), + .help = DNAT_help_v2, + .print = DNAT6v2_print, + .save = DNAT6v2_save, + .x6_parse = DNAT_parse6_v2, + .x6_options = DNAT_opts, + .xlate = DNAT6v2_xlate, + }, +}; + +void _init(void) +{ + xtables_register_targets(nat_tg_reg, ARRAY_SIZE(nat_tg_reg)); +} |