| #include <stdio.h> |
| #include <netdb.h> |
| #include <string.h> |
| #include <stdlib.h> |
| #include <xtables.h> |
| #include <iptables.h> |
| #include <limits.h> /* INT_MAX in ip_tables.h */ |
| #include <linux/netfilter_ipv4/ip_tables.h> |
| #include <linux/netfilter/nf_nat.h> |
| |
| enum { |
| O_TO_SRC = 0, |
| O_RANDOM, |
| O_RANDOM_FULLY, |
| O_PERSISTENT, |
| O_X_TO_SRC, |
| F_TO_SRC = 1 << O_TO_SRC, |
| F_RANDOM = 1 << O_RANDOM, |
| F_RANDOM_FULLY = 1 << O_RANDOM_FULLY, |
| F_X_TO_SRC = 1 << O_X_TO_SRC, |
| }; |
| |
| /* Source NAT data consists of a multi-range, indicating where to map |
| to. */ |
| struct ipt_natinfo |
| { |
| struct xt_entry_target t; |
| struct nf_nat_ipv4_multi_range_compat mr; |
| }; |
| |
| 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 const struct xt_option_entry SNAT_opts[] = { |
| {.name = "to-source", .id = O_TO_SRC, .type = XTTYPE_STRING, |
| .flags = XTOPT_MAND | XTOPT_MULTI}, |
| {.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 struct ipt_natinfo * |
| append_range(struct ipt_natinfo *info, const struct nf_nat_ipv4_range *range) |
| { |
| unsigned int size; |
| |
| /* One rangesize already in struct ipt_natinfo */ |
| size = XT_ALIGN(sizeof(*info) + info->mr.rangesize * sizeof(*range)); |
| |
| info = realloc(info, size); |
| if (!info) |
| xtables_error(OTHER_PROBLEM, "Out of memory\n"); |
| |
| info->t.u.target_size = size; |
| info->mr.range[info->mr.rangesize] = *range; |
| info->mr.rangesize++; |
| |
| return info; |
| } |
| |
| /* Ranges expected in network order. */ |
| static struct xt_entry_target * |
| parse_to(const char *orig_arg, int portok, struct ipt_natinfo *info) |
| { |
| struct nf_nat_ipv4_range range; |
| char *arg, *colon, *dash, *error; |
| const struct in_addr *ip; |
| |
| arg = strdup(orig_arg); |
| if (arg == NULL) |
| xtables_error(RESOURCE_PROBLEM, "strdup"); |
| memset(&range, 0, sizeof(range)); |
| colon = strchr(arg, ':'); |
| |
| if (colon) { |
| int port; |
| |
| if (!portok) |
| xtables_error(PARAMETER_PROBLEM, |
| "Need TCP, UDP, SCTP or DCCP with port specification"); |
| |
| range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED; |
| |
| port = atoi(colon+1); |
| if (port <= 0 || port > 65535) |
| xtables_error(PARAMETER_PROBLEM, |
| "Port `%s' not valid\n", colon+1); |
| |
| error = strchr(colon+1, ':'); |
| if (error) |
| xtables_error(PARAMETER_PROBLEM, |
| "Invalid port:port syntax - use dash\n"); |
| |
| dash = strchr(colon, '-'); |
| if (!dash) { |
| range.min.tcp.port |
| = range.max.tcp.port |
| = htons(port); |
| } else { |
| int maxport; |
| |
| maxport = atoi(dash + 1); |
| if (maxport <= 0 || maxport > 65535) |
| xtables_error(PARAMETER_PROBLEM, |
| "Port `%s' not valid\n", dash+1); |
| if (maxport < port) |
| /* People are stupid. */ |
| xtables_error(PARAMETER_PROBLEM, |
| "Port range `%s' funky\n", colon+1); |
| range.min.tcp.port = htons(port); |
| range.max.tcp.port = htons(maxport); |
| } |
| /* Starts with a colon? No IP info...*/ |
| if (colon == arg) { |
| free(arg); |
| return &(append_range(info, &range)->t); |
| } |
| *colon = '\0'; |
| } |
| |
| range.flags |= NF_NAT_RANGE_MAP_IPS; |
| dash = strchr(arg, '-'); |
| if (colon && dash && dash > colon) |
| dash = NULL; |
| |
| if (dash) |
| *dash = '\0'; |
| |
| ip = xtables_numeric_to_ipaddr(arg); |
| if (!ip) |
| xtables_error(PARAMETER_PROBLEM, "Bad IP address \"%s\"\n", |
| arg); |
| range.min_ip = ip->s_addr; |
| if (dash) { |
| ip = xtables_numeric_to_ipaddr(dash+1); |
| if (!ip) |
| xtables_error(PARAMETER_PROBLEM, "Bad IP address \"%s\"\n", |
| dash+1); |
| range.max_ip = ip->s_addr; |
| } else |
| range.max_ip = range.min_ip; |
| |
| free(arg); |
| return &(append_range(info, &range)->t); |
| } |
| |
| static void SNAT_parse(struct xt_option_call *cb) |
| { |
| const struct ipt_entry *entry = cb->xt_entry; |
| struct ipt_natinfo *info = (void *)(*cb->target); |
| int portok; |
| |
| if (entry->ip.proto == IPPROTO_TCP |
| || entry->ip.proto == IPPROTO_UDP |
| || entry->ip.proto == IPPROTO_SCTP |
| || entry->ip.proto == IPPROTO_DCCP |
| || entry->ip.proto == IPPROTO_ICMP) |
| portok = 1; |
| else |
| portok = 0; |
| |
| xtables_option_parse(cb); |
| switch (cb->entry->id) { |
| case O_TO_SRC: |
| if (cb->xflags & F_X_TO_SRC) { |
| if (!kernel_version) |
| get_kernel_version(); |
| if (kernel_version > LINUX_VERSION(2, 6, 10)) |
| xtables_error(PARAMETER_PROBLEM, |
| "SNAT: Multiple --to-source not supported"); |
| } |
| *cb->target = parse_to(cb->arg, portok, info); |
| cb->xflags |= F_X_TO_SRC; |
| break; |
| case O_PERSISTENT: |
| info->mr.range[0].flags |= NF_NAT_RANGE_PERSISTENT; |
| break; |
| } |
| } |
| |
| static void SNAT_fcheck(struct xt_fcheck_call *cb) |
| { |
| static const unsigned int f = F_TO_SRC | F_RANDOM; |
| static const unsigned int r = F_TO_SRC | F_RANDOM_FULLY; |
| struct nf_nat_ipv4_multi_range_compat *mr = cb->data; |
| |
| if ((cb->xflags & f) == f) |
| mr->range[0].flags |= NF_NAT_RANGE_PROTO_RANDOM; |
| if ((cb->xflags & r) == r) |
| mr->range[0].flags |= NF_NAT_RANGE_PROTO_RANDOM_FULLY; |
| } |
| |
| static void print_range(const struct nf_nat_ipv4_range *r) |
| { |
| if (r->flags & NF_NAT_RANGE_MAP_IPS) { |
| struct in_addr a; |
| |
| a.s_addr = r->min_ip; |
| printf("%s", xtables_ipaddr_to_numeric(&a)); |
| if (r->max_ip != r->min_ip) { |
| a.s_addr = r->max_ip; |
| printf("-%s", xtables_ipaddr_to_numeric(&a)); |
| } |
| } |
| if (r->flags & NF_NAT_RANGE_PROTO_SPECIFIED) { |
| printf(":"); |
| printf("%hu", ntohs(r->min.tcp.port)); |
| if (r->max.tcp.port != r->min.tcp.port) |
| printf("-%hu", ntohs(r->max.tcp.port)); |
| } |
| } |
| |
| static void SNAT_print(const void *ip, const struct xt_entry_target *target, |
| int numeric) |
| { |
| const struct ipt_natinfo *info = (const void *)target; |
| unsigned int i = 0; |
| |
| printf(" to:"); |
| for (i = 0; i < info->mr.rangesize; i++) { |
| print_range(&info->mr.range[i]); |
| if (info->mr.range[i].flags & NF_NAT_RANGE_PROTO_RANDOM) |
| printf(" random"); |
| if (info->mr.range[i].flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY) |
| printf(" random-fully"); |
| if (info->mr.range[i].flags & NF_NAT_RANGE_PERSISTENT) |
| printf(" persistent"); |
| } |
| } |
| |
| static void SNAT_save(const void *ip, const struct xt_entry_target *target) |
| { |
| const struct ipt_natinfo *info = (const void *)target; |
| unsigned int i = 0; |
| |
| for (i = 0; i < info->mr.rangesize; i++) { |
| printf(" --to-source "); |
| print_range(&info->mr.range[i]); |
| if (info->mr.range[i].flags & NF_NAT_RANGE_PROTO_RANDOM) |
| printf(" --random"); |
| if (info->mr.range[i].flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY) |
| printf(" --random-fully"); |
| if (info->mr.range[i].flags & NF_NAT_RANGE_PERSISTENT) |
| printf(" --persistent"); |
| } |
| } |
| |
| static void print_range_xlate(const struct nf_nat_ipv4_range *r, |
| struct xt_xlate *xl) |
| { |
| if (r->flags & NF_NAT_RANGE_MAP_IPS) { |
| struct in_addr a; |
| |
| a.s_addr = r->min_ip; |
| xt_xlate_add(xl, "%s", xtables_ipaddr_to_numeric(&a)); |
| if (r->max_ip != r->min_ip) { |
| a.s_addr = r->max_ip; |
| xt_xlate_add(xl, "-%s", xtables_ipaddr_to_numeric(&a)); |
| } |
| } |
| if (r->flags & NF_NAT_RANGE_PROTO_SPECIFIED) { |
| xt_xlate_add(xl, ":"); |
| xt_xlate_add(xl, "%hu", ntohs(r->min.tcp.port)); |
| if (r->max.tcp.port != r->min.tcp.port) |
| xt_xlate_add(xl, "-%hu", ntohs(r->max.tcp.port)); |
| } |
| } |
| |
| static int SNAT_xlate(struct xt_xlate *xl, |
| const struct xt_xlate_tg_params *params) |
| { |
| const struct ipt_natinfo *info = (const void *)params->target; |
| unsigned int i = 0; |
| bool sep_need = false; |
| const char *sep = " "; |
| |
| for (i = 0; i < info->mr.rangesize; i++) { |
| xt_xlate_add(xl, "snat to "); |
| print_range_xlate(&info->mr.range[i], xl); |
| if (info->mr.range[i].flags & NF_NAT_RANGE_PROTO_RANDOM) { |
| xt_xlate_add(xl, " random"); |
| sep_need = true; |
| } |
| if (info->mr.range[i].flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY) { |
| if (sep_need) |
| sep = ","; |
| xt_xlate_add(xl, "%sfully-random", sep); |
| sep_need = true; |
| } |
| if (info->mr.range[i].flags & NF_NAT_RANGE_PERSISTENT) { |
| if (sep_need) |
| sep = ","; |
| xt_xlate_add(xl, "%spersistent", sep); |
| } |
| } |
| |
| return 1; |
| } |
| |
| static struct xtables_target snat_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 = SNAT_parse, |
| .x6_fcheck = SNAT_fcheck, |
| .print = SNAT_print, |
| .save = SNAT_save, |
| .x6_options = SNAT_opts, |
| .xlate = SNAT_xlate, |
| }; |
| |
| void _init(void) |
| { |
| xtables_register_target(&snat_tg_reg); |
| } |