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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <errno.h>
#include <stddef.h>
#include <string.h>
#include "alloc-util.h"
#include "firewall-util.h"
#include "firewall-util-private.h"
#include "log.h"
#include "netlink-util.h"
#include "string-table.h"
static const char * const firewall_backend_table[_FW_BACKEND_MAX] = {
[FW_BACKEND_NONE] = "none",
#if HAVE_LIBIPTC
[FW_BACKEND_IPTABLES] = "iptables",
#endif
[FW_BACKEND_NFTABLES] = "nftables",
};
DEFINE_STRING_TABLE_LOOKUP_TO_STRING(firewall_backend, FirewallBackend);
static void firewall_backend_probe(FirewallContext *ctx, bool init_tables) {
const char *e;
assert(ctx);
if (ctx->backend != _FW_BACKEND_INVALID)
return;
e = secure_getenv("SYSTEMD_FIREWALL_BACKEND");
if (e) {
if (streq(e, "nftables"))
ctx->backend = FW_BACKEND_NFTABLES;
else if (streq(e, "iptables"))
#if HAVE_LIBIPTC
ctx->backend = FW_BACKEND_IPTABLES;
#else
log_debug("Unsupported firewall backend requested, ignoring: %s", e);
#endif
else
log_debug("Unrecognized $SYSTEMD_FIREWALL_BACKEND value, ignoring: %s", e);
}
if (ctx->backend == _FW_BACKEND_INVALID) {
if (fw_nftables_init_full(ctx, init_tables) >= 0)
ctx->backend = FW_BACKEND_NFTABLES;
else
#if HAVE_LIBIPTC
ctx->backend = FW_BACKEND_IPTABLES;
#else
ctx->backend = FW_BACKEND_NONE;
#endif
}
if (ctx->backend != FW_BACKEND_NONE)
log_debug("Using %s as firewall backend.", firewall_backend_to_string(ctx->backend));
else
log_debug("No firewall backend found.");
}
int fw_ctx_new_full(FirewallContext **ret, bool init_tables) {
_cleanup_free_ FirewallContext *ctx = NULL;
ctx = new(FirewallContext, 1);
if (!ctx)
return -ENOMEM;
*ctx = (FirewallContext) {
.backend = _FW_BACKEND_INVALID,
};
firewall_backend_probe(ctx, init_tables);
*ret = TAKE_PTR(ctx);
return 0;
}
int fw_ctx_new(FirewallContext **ret) {
return fw_ctx_new_full(ret, /* init_tables= */ true);
}
FirewallContext *fw_ctx_free(FirewallContext *ctx) {
if (!ctx)
return NULL;
fw_nftables_exit(ctx);
return mfree(ctx);
}
size_t fw_ctx_get_reply_callback_count(FirewallContext *ctx) {
if (!ctx || !ctx->nfnl)
return 0;
return netlink_get_reply_callback_count(ctx->nfnl);
}
int fw_add_masquerade(
FirewallContext **ctx,
bool add,
int af,
const union in_addr_union *source,
unsigned source_prefixlen) {
int r;
assert(ctx);
if (!*ctx) {
r = fw_ctx_new(ctx);
if (r < 0)
return r;
}
switch ((*ctx)->backend) {
#if HAVE_LIBIPTC
case FW_BACKEND_IPTABLES:
return fw_iptables_add_masquerade(add, af, source, source_prefixlen);
#endif
case FW_BACKEND_NFTABLES:
return fw_nftables_add_masquerade(*ctx, add, af, source, source_prefixlen);
default:
return -EOPNOTSUPP;
}
}
int fw_add_local_dnat(
FirewallContext **ctx,
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) {
int r;
assert(ctx);
if (!*ctx) {
r = fw_ctx_new(ctx);
if (r < 0)
return r;
}
switch ((*ctx)->backend) {
#if HAVE_LIBIPTC
case FW_BACKEND_IPTABLES:
return fw_iptables_add_local_dnat(add, af, protocol, local_port, remote, remote_port, previous_remote);
#endif
case FW_BACKEND_NFTABLES:
return fw_nftables_add_local_dnat(*ctx, add, af, protocol, local_port, remote, remote_port, previous_remote);
default:
return -EOPNOTSUPP;
}
}
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