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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 15:35:18 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 15:35:18 +0000 |
commit | b750101eb236130cf056c675997decbac904cc49 (patch) | |
tree | a5df1a06754bdd014cb975c051c83b01c9a97532 /src/shared/firewall-util-iptables.c | |
parent | Initial commit. (diff) | |
download | systemd-upstream.tar.xz systemd-upstream.zip |
Adding upstream version 252.22.upstream/252.22upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | src/shared/firewall-util-iptables.c | 363 |
1 files changed, 363 insertions, 0 deletions
diff --git a/src/shared/firewall-util-iptables.c b/src/shared/firewall-util-iptables.c new file mode 100644 index 0000000..55bb427 --- /dev/null +++ b/src/shared/firewall-util-iptables.c @@ -0,0 +1,363 @@ +/* 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_safe(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; +} |