| /* SPDX-License-Identifier: LGPL-2.1-or-later */ |
| |
| /* Temporary work-around for broken glibc vs. linux kernel header definitions |
| * This is already fixed upstream, remove this when distributions have updated. |
| */ |
| #define _NET_IF_H 1 |
| |
| #include <arpa/inet.h> |
| #include <endian.h> |
| #include <errno.h> |
| #include <stddef.h> |
| #include <string.h> |
| #include <net/if.h> |
| #ifndef IFNAMSIZ |
| #define IFNAMSIZ 16 |
| #endif |
| #include <linux/if.h> |
| #include <linux/netfilter_ipv4/ip_tables.h> |
| #include <linux/netfilter/nf_nat.h> |
| #include <linux/netfilter/xt_addrtype.h> |
| #include <libiptc/libiptc.h> |
| |
| #include "alloc-util.h" |
| #include "firewall-util.h" |
| #include "firewall-util-private.h" |
| #include "in-addr-util.h" |
| #include "macro.h" |
| #include "socket-util.h" |
| |
| DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(struct xtc_handle*, iptc_free, NULL); |
| |
| static int entry_fill_basics( |
| struct ipt_entry *entry, |
| int protocol, |
| const char *in_interface, |
| const union in_addr_union *source, |
| unsigned source_prefixlen, |
| const char *out_interface, |
| const union in_addr_union *destination, |
| unsigned destination_prefixlen) { |
| |
| assert(entry); |
| |
| if (out_interface && !ifname_valid(out_interface)) |
| return -EINVAL; |
| if (in_interface && !ifname_valid(in_interface)) |
| return -EINVAL; |
| |
| entry->ip.proto = protocol; |
| |
| if (in_interface) { |
| size_t l; |
| |
| l = strlen(in_interface); |
| assert(l < sizeof entry->ip.iniface); |
| assert(l < sizeof entry->ip.iniface_mask); |
| |
| strcpy(entry->ip.iniface, in_interface); |
| memset(entry->ip.iniface_mask, 0xFF, l + 1); |
| } |
| if (source) { |
| entry->ip.src = source->in; |
| in4_addr_prefixlen_to_netmask(&entry->ip.smsk, source_prefixlen); |
| } |
| |
| if (out_interface) { |
| size_t l = strlen(out_interface); |
| assert(l < sizeof entry->ip.outiface); |
| assert(l < sizeof entry->ip.outiface_mask); |
| |
| strcpy(entry->ip.outiface, out_interface); |
| memset(entry->ip.outiface_mask, 0xFF, l + 1); |
| } |
| if (destination) { |
| entry->ip.dst = destination->in; |
| in4_addr_prefixlen_to_netmask(&entry->ip.dmsk, destination_prefixlen); |
| } |
| |
| return 0; |
| } |
| |
| int fw_iptables_add_masquerade( |
| bool add, |
| int af, |
| const union in_addr_union *source, |
| unsigned source_prefixlen) { |
| |
| static const xt_chainlabel chain = "POSTROUTING"; |
| _cleanup_(iptc_freep) struct xtc_handle *h = NULL; |
| struct ipt_entry *entry, *mask; |
| struct ipt_entry_target *t; |
| size_t sz; |
| struct nf_nat_ipv4_multi_range_compat *mr; |
| int r, protocol = 0; |
| const char *out_interface = NULL; |
| const union in_addr_union *destination = NULL; |
| unsigned destination_prefixlen = 0; |
| |
| if (af != AF_INET) |
| return -EOPNOTSUPP; |
| |
| if (!source || source_prefixlen == 0) |
| return -EINVAL; |
| |
| r = fw_iptables_init_nat(&h); |
| if (r < 0) |
| return r; |
| |
| sz = XT_ALIGN(sizeof(struct ipt_entry)) + |
| XT_ALIGN(sizeof(struct ipt_entry_target)) + |
| XT_ALIGN(sizeof(struct nf_nat_ipv4_multi_range_compat)); |
| |
| /* Put together the entry we want to add or remove */ |
| entry = alloca0(sz); |
| entry->next_offset = sz; |
| entry->target_offset = XT_ALIGN(sizeof(struct ipt_entry)); |
| r = entry_fill_basics(entry, protocol, NULL, source, source_prefixlen, out_interface, destination, destination_prefixlen); |
| if (r < 0) |
| return r; |
| |
| /* Fill in target part */ |
| t = ipt_get_target(entry); |
| t->u.target_size = |
| XT_ALIGN(sizeof(struct ipt_entry_target)) + |
| XT_ALIGN(sizeof(struct nf_nat_ipv4_multi_range_compat)); |
| strncpy(t->u.user.name, "MASQUERADE", sizeof(t->u.user.name)); |
| mr = (struct nf_nat_ipv4_multi_range_compat*) t->data; |
| mr->rangesize = 1; |
| |
| /* Create a search mask entry */ |
| mask = alloca(sz); |
| memset(mask, 0xFF, sz); |
| |
| if (add) { |
| if (iptc_check_entry(chain, entry, (unsigned char*) mask, h)) |
| return 0; |
| if (errno != ENOENT) /* if other error than not existing yet, fail */ |
| return -errno; |
| |
| if (!iptc_insert_entry(chain, entry, 0, h)) |
| return -errno; |
| } else { |
| if (!iptc_delete_entry(chain, entry, (unsigned char*) mask, h)) { |
| if (errno == ENOENT) /* if it's already gone, all is good! */ |
| return 0; |
| |
| return -errno; |
| } |
| } |
| |
| if (!iptc_commit(h)) |
| return -errno; |
| |
| return 0; |
| } |
| |
| int fw_iptables_add_local_dnat( |
| bool add, |
| int af, |
| int protocol, |
| uint16_t local_port, |
| const union in_addr_union *remote, |
| uint16_t remote_port, |
| const union in_addr_union *previous_remote) { |
| |
| static const xt_chainlabel chain_pre = "PREROUTING", chain_output = "OUTPUT"; |
| _cleanup_(iptc_freep) struct xtc_handle *h = NULL; |
| struct ipt_entry *entry, *mask; |
| struct ipt_entry_target *t; |
| struct ipt_entry_match *m; |
| struct xt_addrtype_info_v1 *at; |
| struct nf_nat_ipv4_multi_range_compat *mr; |
| size_t sz, msz; |
| int r; |
| const char *in_interface = NULL; |
| const union in_addr_union *source = NULL; |
| unsigned source_prefixlen = 0; |
| const union in_addr_union *destination = NULL; |
| unsigned destination_prefixlen = 0; |
| |
| assert(add || !previous_remote); |
| |
| if (af != AF_INET) |
| return -EOPNOTSUPP; |
| |
| if (!IN_SET(protocol, IPPROTO_TCP, IPPROTO_UDP)) |
| return -EOPNOTSUPP; |
| |
| if (local_port <= 0) |
| return -EINVAL; |
| |
| if (remote_port <= 0) |
| return -EINVAL; |
| |
| r = fw_iptables_init_nat(&h); |
| if (r < 0) |
| return r; |
| |
| sz = XT_ALIGN(sizeof(struct ipt_entry)) + |
| XT_ALIGN(sizeof(struct ipt_entry_match)) + |
| XT_ALIGN(sizeof(struct xt_addrtype_info_v1)) + |
| XT_ALIGN(sizeof(struct ipt_entry_target)) + |
| XT_ALIGN(sizeof(struct nf_nat_ipv4_multi_range_compat)); |
| |
| if (protocol == IPPROTO_TCP) |
| msz = XT_ALIGN(sizeof(struct ipt_entry_match)) + |
| XT_ALIGN(sizeof(struct xt_tcp)); |
| else |
| msz = XT_ALIGN(sizeof(struct ipt_entry_match)) + |
| XT_ALIGN(sizeof(struct xt_udp)); |
| |
| sz += msz; |
| |
| /* Fill in basic part */ |
| entry = alloca0(sz); |
| entry->next_offset = sz; |
| entry->target_offset = |
| XT_ALIGN(sizeof(struct ipt_entry)) + |
| XT_ALIGN(sizeof(struct ipt_entry_match)) + |
| XT_ALIGN(sizeof(struct xt_addrtype_info_v1)) + |
| msz; |
| r = entry_fill_basics(entry, protocol, in_interface, source, source_prefixlen, NULL, destination, destination_prefixlen); |
| if (r < 0) |
| return r; |
| |
| /* Fill in first match */ |
| m = (struct ipt_entry_match*) ((uint8_t*) entry + XT_ALIGN(sizeof(struct ipt_entry))); |
| m->u.match_size = msz; |
| if (protocol == IPPROTO_TCP) { |
| struct xt_tcp *tcp; |
| |
| strncpy(m->u.user.name, "tcp", sizeof(m->u.user.name)); |
| tcp = (struct xt_tcp*) m->data; |
| tcp->dpts[0] = tcp->dpts[1] = local_port; |
| tcp->spts[0] = 0; |
| tcp->spts[1] = 0xFFFF; |
| |
| } else { |
| struct xt_udp *udp; |
| |
| strncpy(m->u.user.name, "udp", sizeof(m->u.user.name)); |
| udp = (struct xt_udp*) m->data; |
| udp->dpts[0] = udp->dpts[1] = local_port; |
| udp->spts[0] = 0; |
| udp->spts[1] = 0xFFFF; |
| } |
| |
| /* Fill in second match */ |
| m = (struct ipt_entry_match*) ((uint8_t*) entry + XT_ALIGN(sizeof(struct ipt_entry)) + msz); |
| m->u.match_size = |
| XT_ALIGN(sizeof(struct ipt_entry_match)) + |
| XT_ALIGN(sizeof(struct xt_addrtype_info_v1)); |
| strncpy(m->u.user.name, "addrtype", sizeof(m->u.user.name)); |
| m->u.user.revision = 1; |
| at = (struct xt_addrtype_info_v1*) m->data; |
| at->dest = XT_ADDRTYPE_LOCAL; |
| |
| /* Fill in target part */ |
| t = ipt_get_target(entry); |
| t->u.target_size = |
| XT_ALIGN(sizeof(struct ipt_entry_target)) + |
| XT_ALIGN(sizeof(struct nf_nat_ipv4_multi_range_compat)); |
| strncpy(t->u.user.name, "DNAT", sizeof(t->u.user.name)); |
| mr = (struct nf_nat_ipv4_multi_range_compat*) t->data; |
| mr->rangesize = 1; |
| mr->range[0].flags = NF_NAT_RANGE_PROTO_SPECIFIED|NF_NAT_RANGE_MAP_IPS; |
| mr->range[0].min_ip = mr->range[0].max_ip = remote->in.s_addr; |
| if (protocol == IPPROTO_TCP) |
| mr->range[0].min.tcp.port = mr->range[0].max.tcp.port = htobe16(remote_port); |
| else |
| mr->range[0].min.udp.port = mr->range[0].max.udp.port = htobe16(remote_port); |
| |
| mask = alloca0(sz); |
| memset(mask, 0xFF, sz); |
| |
| if (add) { |
| /* Add the PREROUTING rule, if it is missing so far */ |
| if (!iptc_check_entry(chain_pre, entry, (unsigned char*) mask, h)) { |
| if (errno != ENOENT) |
| return -EINVAL; |
| |
| if (!iptc_insert_entry(chain_pre, entry, 0, h)) |
| return -errno; |
| } |
| |
| /* If a previous remote is set, remove its entry */ |
| if (previous_remote && previous_remote->in.s_addr != remote->in.s_addr) { |
| mr->range[0].min_ip = mr->range[0].max_ip = previous_remote->in.s_addr; |
| |
| if (!iptc_delete_entry(chain_pre, entry, (unsigned char*) mask, h)) { |
| if (errno != ENOENT) |
| return -errno; |
| } |
| |
| mr->range[0].min_ip = mr->range[0].max_ip = remote->in.s_addr; |
| } |
| |
| /* Add the OUTPUT rule, if it is missing so far */ |
| if (!in_interface) { |
| |
| /* Don't apply onto loopback addresses */ |
| if (!destination) { |
| entry->ip.dst.s_addr = htobe32(0x7F000000); |
| entry->ip.dmsk.s_addr = htobe32(0xFF000000); |
| entry->ip.invflags = IPT_INV_DSTIP; |
| } |
| |
| if (!iptc_check_entry(chain_output, entry, (unsigned char*) mask, h)) { |
| if (errno != ENOENT) |
| return -errno; |
| |
| if (!iptc_insert_entry(chain_output, entry, 0, h)) |
| return -errno; |
| } |
| |
| /* If a previous remote is set, remove its entry */ |
| if (previous_remote && previous_remote->in.s_addr != remote->in.s_addr) { |
| mr->range[0].min_ip = mr->range[0].max_ip = previous_remote->in.s_addr; |
| |
| if (!iptc_delete_entry(chain_output, entry, (unsigned char*) mask, h)) { |
| if (errno != ENOENT) |
| return -errno; |
| } |
| } |
| } |
| } else { |
| if (!iptc_delete_entry(chain_pre, entry, (unsigned char*) mask, h)) { |
| if (errno != ENOENT) |
| return -errno; |
| } |
| |
| if (!in_interface) { |
| if (!destination) { |
| entry->ip.dst.s_addr = htobe32(0x7F000000); |
| entry->ip.dmsk.s_addr = htobe32(0xFF000000); |
| entry->ip.invflags = IPT_INV_DSTIP; |
| } |
| |
| if (!iptc_delete_entry(chain_output, entry, (unsigned char*) mask, h)) { |
| if (errno != ENOENT) |
| return -errno; |
| } |
| } |
| } |
| |
| if (!iptc_commit(h)) |
| return -errno; |
| |
| return 0; |
| } |
| |
| int fw_iptables_init_nat(struct xtc_handle **ret) { |
| _cleanup_(iptc_freep) struct xtc_handle *h = NULL; |
| |
| h = iptc_init("nat"); |
| if (!h) |
| return log_debug_errno(errno, "Failed to init \"nat\" table: %s", iptc_strerror(errno)); |
| |
| if (ret) |
| *ret = TAKE_PTR(h); |
| |
| return 0; |
| } |
