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firewall-util: add ipv6 support to nftables backend

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closely mirrors the existing ipv4 ruleset:
table ip6 io.systemd.nat {
        set masq_saddr {
                type ipv6_addr
                flags interval
        }

        map map_port_ipport {
                type inet_proto . inet_service : ipv6_addr . inet_service
        }

        chain prerouting {
                type nat hook prerouting priority dstnat + 1; policy accept;
                fib daddr type local dnat ip6 addr . port to meta l4proto . th dport map @map_port_ipport
        }

        chain output {
                type nat hook output priority -99; policy accept;
                ip6 daddr != ::1 oif "lo" dnat ip6 addr . port to meta l4proto . th dport map @map_port_ipport
        }

        chain postrouting {
                type nat hook postrouting priority srcnat + 1; policy accept;
                ip6 saddr @masq_saddr masquerade
        }
}

Only difference is the use of ipv6 addresses instead of ipv4 ones.

Currently has no effect: all in-tree callers pass AF_INET exclusively.
Followup patches will make nspawn expose ipv6 too and rework
IPMasquerade option to support both/v4/v6.
This commit is contained in:
Florian Westphal 2020-09-17 21:55:45 +02:00
parent 656e5aa452
commit 0e544221c9
2 changed files with 204 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

179
src/shared/firewall-util-nft.c
View File

@ -9,6 +9,7 @@
#include <linux/netfilter/nf_nat.h>
#include <linux/netfilter_ipv4.h>
#include <netinet/ip.h>
#include <netinet/ip6.h>
#include "sd-netlink.h"
@ -17,6 +18,7 @@
#include "firewall-util-private.h"
#include "in-addr-util.h"
#include "macro.h"
#include "memory-util.h"
#include "socket-util.h"
#include "time-util.h"
@ -329,9 +331,13 @@ static int sd_nfnl_message_new_masq_rule(sd_netlink *nfnl, sd_netlink_message **
if (r < 0)
return r;
/* 1st statement: ip saddr @masq_saddr. Place iph->saddr in reg1. */
r = nfnl_add_expr_payload(m, NFT_PAYLOAD_NETWORK_HEADER, offsetof(struct iphdr, saddr),
sizeof(uint32_t), NFT_REG32_01);
/* 1st statement: ip saddr @masq_saddr. Place iph->saddr in reg1, resp. ipv6 in reg1..reg4. */
if (family == AF_INET)
r = nfnl_add_expr_payload(m, NFT_PAYLOAD_NETWORK_HEADER, offsetof(struct iphdr, saddr),
sizeof(uint32_t), NFT_REG32_01);
else
r = nfnl_add_expr_payload(m, NFT_PAYLOAD_NETWORK_HEADER, offsetof(struct ip6_hdr, ip6_src.s6_addr),
sizeof(struct in6_addr), NFT_REG32_01);
if (r < 0)
return r;
@ -397,7 +403,7 @@ static int sd_nfnl_message_new_dnat_rule_pre(sd_netlink *nfnl, sd_netlink_messag
if (r < 0)
return r;
proto_reg = NFT_REG32_02;
proto_reg = family == AF_INET ? NFT_REG32_02 : NFT_REG32_05;
r = nfnl_add_expr_dnat(m, family, NFT_REG32_01, proto_reg);
if (r < 0)
return r;
@ -411,9 +417,8 @@ static int sd_nfnl_message_new_dnat_rule_pre(sd_netlink *nfnl, sd_netlink_messag
static int sd_nfnl_message_new_dnat_rule_out(sd_netlink *nfnl, sd_netlink_message **ret,
int family, const char *chain) {
static const uint32_t zero, one = 1;
static const uint32_t zero = 0, one = 1;
uint32_t lonet = htobe32(0x7F000000), lomask = htobe32(0xff000000);
_cleanup_(sd_netlink_message_unrefp) sd_netlink_message *m = NULL;
enum nft_registers proto_reg;
int r;
@ -426,19 +431,31 @@ static int sd_nfnl_message_new_dnat_rule_out(sd_netlink *nfnl, sd_netlink_messag
if (r < 0)
return r;
/* 1st statement: exclude 127.0.0.1/8: ip daddr != 127.0.0.1/8 */
r = nfnl_add_expr_payload(m, NFT_PAYLOAD_NETWORK_HEADER, offsetof(struct iphdr, daddr),
sizeof(uint32_t), NFT_REG32_01);
if (r < 0)
return r;
/* 1st statement: exclude 127.0.0.1/8: ip daddr != 127.0.0.1/8, resp. avoid ::1 */
if (family == AF_INET) {
uint32_t lonet = htobe32(UINT32_C(0x7F000000)), lomask = htobe32(UINT32_C(0xff000000));
/* 1st statement (cont.): bitops/prefix */
r = nfnl_add_expr_bitwise(m, NFT_REG32_01, NFT_REG32_01, &lomask, &zero, sizeof(lomask));
if (r < 0)
return r;
r = nfnl_add_expr_payload(m, NFT_PAYLOAD_NETWORK_HEADER, offsetof(struct iphdr, daddr),
sizeof(lonet), NFT_REG32_01);
if (r < 0)
return r;
/* 1st statement (cont.): bitops/prefix */
r = nfnl_add_expr_bitwise(m, NFT_REG32_01, NFT_REG32_01, &lomask, &zero, sizeof(lomask));
if (r < 0)
return r;
/* 1st statement (cont.): compare reg1 with 127/8 */
r = nfnl_add_expr_cmp(m, NFT_CMP_NEQ, NFT_REG32_01, &lonet, sizeof(lonet));
/* 1st statement (cont.): compare reg1 with 127/8 */
r = nfnl_add_expr_cmp(m, NFT_CMP_NEQ, NFT_REG32_01, &lonet, sizeof(lonet));
} else {
struct in6_addr loaddr = IN6ADDR_LOOPBACK_INIT;
r = nfnl_add_expr_payload(m, NFT_PAYLOAD_NETWORK_HEADER, offsetof(struct ip6_hdr, ip6_dst.s6_addr),
sizeof(loaddr), NFT_REG32_01);
if (r < 0)
return r;
r = nfnl_add_expr_cmp(m, NFT_CMP_NEQ, NFT_REG32_01, &loaddr, sizeof(loaddr));
}
if (r < 0)
return r;
@ -475,7 +492,7 @@ static int sd_nfnl_message_new_dnat_rule_out(sd_netlink *nfnl, sd_netlink_messag
/* 4th statement: dnat connection to address/port retrieved by the
* preceding expression. */
proto_reg = NFT_REG32_02;
proto_reg = family == AF_INET ? NFT_REG32_02 : NFT_REG32_05;
r = nfnl_add_expr_dnat(m, family, NFT_REG32_01, proto_reg);
if (r < 0)
return r;
@ -620,10 +637,11 @@ static uint32_t concat_types2(enum nft_key_types a, enum nft_key_types b) {
#define NFT_INIT_MSGS 16
static int fw_nftables_init_family(sd_netlink *nfnl, int family) {
sd_netlink_message *batch[NFT_INIT_MSGS] = {};
size_t ip_type_size = sizeof(uint32_t);
int ip_type = TYPE_IPADDR, r;
size_t msgcnt = 0, i;
size_t msgcnt = 0, i, ip_type_size;
uint32_t set_id = 0;
int ip_type, r;
assert(IN_SET(family, AF_INET, AF_INET6));
r = sd_nfnl_message_batch_begin(nfnl, &batch[msgcnt]);
if (r < 0)
@ -661,6 +679,14 @@ static int fw_nftables_init_family(sd_netlink *nfnl, int family) {
if (r < 0)
goto out_unref;
if (family == AF_INET) {
ip_type_size = sizeof(uint32_t);
ip_type = TYPE_IPADDR;
} else {
assert(family == AF_INET6);
ip_type_size = sizeof(struct in6_addr);
ip_type = TYPE_IP6ADDR;
}
msgcnt++;
assert(msgcnt < NFT_INIT_MSGS);
/* set to store ip address ranges we should masquerade for */
@ -731,6 +757,10 @@ int fw_nftables_init(FirewallContext *ctx) {
if (r < 0)
return r;
r = fw_nftables_init_family(nfnl, AF_INET6);
if (r < 0)
log_debug_errno(r, "Failed to init ipv6 NAT: %m");
ctx->nfnl = TAKE_PTR(nfnl);
return 0;
}
@ -815,6 +845,73 @@ static int fw_nftables_recreate_table(sd_netlink *nfnl, int af, sd_netlink_messa
return 0;
}
static void nft_in6addr_to_range(const union in_addr_union *source, unsigned int prefixlen,
struct in6_addr *ret_start, struct in6_addr *ret_end) {
uint8_t carry = 0;
int i, j;
assert(prefixlen <= 128);
for (i = 0, j = 15; i < 16; i++) {
uint8_t nm;
nm = 0xFF;
if (prefixlen < 8)
nm = 0xFF << (8 - prefixlen);
ret_start->s6_addr[i] = source->in6.s6_addr[i] & nm;
if (prefixlen <= 8 && j == 15) {
carry = 1u << (8 - prefixlen);
j = i;
}
if (prefixlen >= 8)
prefixlen -= 8;
else
prefixlen = 0;
}
*ret_end = *ret_start;
for (; j >= 0; j--) {
uint16_t overflow = ret_end->s6_addr[j] + carry;
ret_end->s6_addr[j] = overflow;
if (overflow <= 0xff)
break;
carry = 1;
}
if (memcmp(ret_start, ret_end, sizeof(*ret_start)) > 0)
zero(ret_end);
}
static int nft_message_add_setelem_ip6range(sd_netlink_message *m,
const union in_addr_union *source,
unsigned int prefixlen) {
struct in6_addr start, end;
int r;
nft_in6addr_to_range(source, prefixlen, &start, &end);
r = sd_nfnl_nft_message_add_setelem(m, 0, &start, sizeof(start), NULL, 0);
if (r < 0)
return r;
r = sd_nfnl_nft_message_add_setelem_end(m);
if (r < 0)
return r;
r = sd_nfnl_nft_message_add_setelem(m, 1, &end, sizeof(end), NULL, 0);
if (r < 0)
return r;
r = sd_netlink_message_append_u32(m, NFTA_SET_ELEM_FLAGS, htobe32(NFT_SET_ELEM_INTERVAL_END));
if (r < 0)
return r;
return sd_nfnl_nft_message_add_setelem_end(m);
}
#define NFT_MASQ_MSGS 3
int fw_nftables_add_masquerade(
@ -831,6 +928,8 @@ int fw_nftables_add_masquerade(
if (!source || source_prefixlen == 0)
return -EINVAL;
if (af == AF_INET6 && source_prefixlen < 8)
return -EINVAL;
again:
r = sd_nfnl_message_batch_begin(ctx->nfnl, &transaction[0]);
if (r < 0)
@ -844,7 +943,11 @@ again:
if (r < 0)
goto out_unref;
r = nft_message_add_setelem_iprange(transaction[tsize], source, source_prefixlen);
if (af == AF_INET)
r = nft_message_add_setelem_iprange(transaction[tsize], source, source_prefixlen);
else
r = nft_message_add_setelem_ip6range(transaction[tsize], source, source_prefixlen);
if (r < 0)
goto out_unref;
@ -881,7 +984,7 @@ int fw_nftables_add_local_dnat(
const union in_addr_union *remote,
uint16_t remote_port,
const union in_addr_union *previous_remote) {
uint32_t data[2], key[2];
uint32_t data[5], key[2], dlen;
sd_netlink_message *transaction[NFT_DNAT_MSGS] = {};
bool retry = true;
size_t tsize;
@ -889,9 +992,6 @@ int fw_nftables_add_local_dnat(
assert(add || !previous_remote);
if (af != AF_INET)
return -EAFNOSUPPORT;
if (!IN_SET(protocol, IPPROTO_TCP, IPPROTO_UDP))
return -EPROTONOSUPPORT;
@ -908,7 +1008,14 @@ again:
if (remote_port <= 0)
return -EINVAL;
data[1] = htobe16(remote_port);
if (af == AF_INET) {
dlen = 8;
data[1] = htobe16(remote_port);
} else {
assert(af == AF_INET6);
dlen = sizeof(data);
data[4] = htobe16(remote_port);
}
r = sd_nfnl_message_batch_begin(ctx->nfnl, &transaction[0]);
if (r < 0)
@ -916,23 +1023,29 @@ again:
tsize = 1;
/* If a previous remote is set, remove its entry */
if (add && previous_remote && previous_remote->in.s_addr != remote->in.s_addr) {
data[0] = previous_remote->in.s_addr;
if (add && previous_remote && !in_addr_equal(af, previous_remote, remote)) {
if (af == AF_INET)
data[0] = previous_remote->in.s_addr;
else
memcpy(data, &previous_remote->in6, sizeof(previous_remote->in6));
r = nft_del_element(ctx->nfnl, &transaction[tsize], af, NFT_SYSTEMD_DNAT_MAP_NAME, key, sizeof(key), data, sizeof(data));
r = nft_del_element(ctx->nfnl, &transaction[tsize], af, NFT_SYSTEMD_DNAT_MAP_NAME, key, sizeof(key), data, dlen);
if (r < 0)
goto out_unref;
tsize++;
}
data[0] = remote->in.s_addr;
if (af == AF_INET)
data[0] = remote->in.s_addr;
else
memcpy(data, &remote->in6, sizeof(remote->in6));
assert(tsize < NFT_DNAT_MSGS);
if (add)
nft_add_element(ctx->nfnl, &transaction[tsize], af, NFT_SYSTEMD_DNAT_MAP_NAME, key, sizeof(key), data, sizeof(data));
nft_add_element(ctx->nfnl, &transaction[tsize], af, NFT_SYSTEMD_DNAT_MAP_NAME, key, sizeof(key), data, dlen);
else
nft_del_element(ctx->nfnl, &transaction[tsize], af, NFT_SYSTEMD_DNAT_MAP_NAME, key, sizeof(key), data, sizeof(data));
nft_del_element(ctx->nfnl, &transaction[tsize], af, NFT_SYSTEMD_DNAT_MAP_NAME, key, sizeof(key), data, dlen);
tsize++;
assert(tsize < NFT_DNAT_MSGS);

58
src/test/test-firewall-util.c
View File

@ -1,11 +1,67 @@
/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <arpa/inet.h>
#include <stdlib.h>
#include "firewall-util.h"
#include "log.h"
#include "random-util.h"
#include "tests.h"
#define MAKE_IN_ADDR_UNION(a,b,c,d) (union in_addr_union) { .in.s_addr = htobe32((uint32_t) (a) << 24 | (uint32_t) (b) << 16 | (uint32_t) (c) << 8 | (uint32_t) (d))}
static void make_in6_addr_union(const char *addr, union in_addr_union *u) {
assert_se(inet_pton(AF_INET6, addr, &u->in6) >= 0);
}
static void test_v6(FirewallContext **ctx) {
union in_addr_union u = {}, u2 = {};
uint8_t prefixlen;
int r;
make_in6_addr_union("dead::beef", &u);
r = fw_add_masquerade(ctx, true, AF_INET6, &u, 128);
if (r < 0)
log_error_errno(r, "Failed to modify ipv6 firewall: %m");
r = fw_add_masquerade(ctx, false, AF_INET6, &u, 128);
if (r < 0)
log_error_errno(r, "Failed to modify ipv6 firewall: %m");
r = fw_add_masquerade(ctx, true, AF_INET6, &u, 64);
if (r < 0)
log_error_errno(r, "Failed to modify ipv6 firewall: %m");
r = fw_add_masquerade(ctx, false, AF_INET6, &u, 64);
if (r < 0)
log_error_errno(r, "Failed to modify ipv6 firewall: %m");
r = fw_add_local_dnat(ctx, true, AF_INET6, IPPROTO_TCP, 4711, &u, 815, NULL);
if (r < 0)
log_error_errno(r, "Failed to modify firewall: %m");
make_in6_addr_union("1c3::c01d", &u2);
r = fw_add_local_dnat(ctx, true, AF_INET6, IPPROTO_TCP, 4711, &u2, 815, &u);
if (r < 0)
log_error_errno(r, "Failed to modify firewall: %m");
r = fw_add_local_dnat(ctx, false, AF_INET6, IPPROTO_TCP, 4711, &u2, 815, NULL);
if (r < 0)
log_error_errno(r, "Failed to modify firewall: %m");
prefixlen = random_u32() % (128 + 1 - 8);
prefixlen += 8;
pseudo_random_bytes(&u, sizeof(u));
r = fw_add_masquerade(ctx, true, AF_INET6, &u, prefixlen);
if (r < 0)
log_error_errno(r, "Failed to modify ipv6 firewall: %m");
r = fw_add_masquerade(ctx, false, AF_INET6, &u, prefixlen);
if (r < 0)
log_error_errno(r, "Failed to modify ipv6 firewall: %m");
}
int main(int argc, char *argv[]) {
_cleanup_(fw_ctx_freep) FirewallContext *ctx;
int r;
@ -57,5 +113,7 @@ int main(int argc, char *argv[]) {
if (r < 0)
log_error_errno(r, "Failed to modify firewall: %m");
test_v6(&ctx);
return 0;
}