1 files changed, 160 insertions, 0 deletions
diff --git a/src/shared/firewall-util.c b/src/shared/firewall-util.c
new file mode 100644
index 0000000..e96b24a
--- /dev/null
+++ b/src/shared/firewall-util.c
@@ -0,0 +1,160 @@
+/* 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;
+        }
+}