// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
/* Copyright Authors of Cilium */

#include <bpf/ctx/xdp.h>
#include <bpf/api.h>

#include <node_config.h>
#include <netdev_config.h>
#include <filter_config.h>

#define SKIP_POLICY_MAP 1

/* Controls the inclusion of the CILIUM_CALL_HANDLE_ICMP6_NS section in the
 * bpf_lxc object file.
 */
#define SKIP_ICMPV6_NS_HANDLING

/* Controls the inclusion of the CILIUM_CALL_SEND_ICMP6_TIME_EXCEEDED section
 * in the bpf_lxc object file. This is needed for all callers of
 * ipv6_local_delivery, which calls into the IPv6 L3 handling.
 */
#define SKIP_ICMPV6_HOPLIMIT_HANDLING

/* Controls the inclusion of the CILIUM_CALL_SRV6 section in the object file.
 */
#define SKIP_SRV6_HANDLING

/* The XDP datapath does not take care of health probes from the local node,
 * thus do not compile it in.
 */
#undef ENABLE_HEALTH_CHECK

#include "lib/common.h"
#include "lib/maps.h"
#include "lib/eps.h"
#include "lib/events.h"
#include "lib/nodeport.h"

#ifdef ENABLE_PREFILTER
#ifdef CIDR4_FILTER
struct {
	__uint(type, BPF_MAP_TYPE_HASH);
	__type(key, struct lpm_v4_key);
	__type(value, struct lpm_val);
	__uint(pinning, LIBBPF_PIN_BY_NAME);
	__uint(max_entries, CIDR4_HMAP_ELEMS);
	__uint(map_flags, BPF_F_NO_PREALLOC);
} CIDR4_HMAP_NAME __section_maps_btf;

#ifdef CIDR4_LPM_PREFILTER
struct {
	__uint(type, BPF_MAP_TYPE_LPM_TRIE);
	__type(key, struct lpm_v4_key);
	__type(value, struct lpm_val);
	__uint(pinning, LIBBPF_PIN_BY_NAME);
	__uint(max_entries, CIDR4_LMAP_ELEMS);
	__uint(map_flags, BPF_F_NO_PREALLOC);
} CIDR4_LMAP_NAME __section_maps_btf;

#endif /* CIDR4_LPM_PREFILTER */
#endif /* CIDR4_FILTER */

#ifdef CIDR6_FILTER
struct {
	__uint(type, BPF_MAP_TYPE_HASH);
	__type(key, struct lpm_v6_key);
	__type(value, struct lpm_val);
	__uint(pinning, LIBBPF_PIN_BY_NAME);
	__uint(max_entries, CIDR4_HMAP_ELEMS);
	__uint(map_flags, BPF_F_NO_PREALLOC);
} CIDR6_HMAP_NAME __section_maps_btf;

#ifdef CIDR6_LPM_PREFILTER
struct {
	__uint(type, BPF_MAP_TYPE_LPM_TRIE);
	__type(key, struct lpm_v6_key);
	__type(value, struct lpm_val);
	__uint(pinning, LIBBPF_PIN_BY_NAME);
	__uint(max_entries, CIDR4_LMAP_ELEMS);
	__uint(map_flags, BPF_F_NO_PREALLOC);
} CIDR6_LMAP_NAME __section_maps_btf;
#endif /* CIDR6_LPM_PREFILTER */
#endif /* CIDR6_FILTER */
#endif /* ENABLE_PREFILTER */

static __always_inline __maybe_unused int
bpf_xdp_exit(struct __ctx_buff *ctx, const int verdict)
{
	if (verdict == CTX_ACT_OK)
		ctx_move_xfer(ctx);

	return verdict;
}

#ifdef ENABLE_IPV4
#ifdef ENABLE_NODEPORT_ACCELERATION
__section_tail(CILIUM_MAP_CALLS, CILIUM_CALL_IPV4_FROM_NETDEV)
int tail_lb_ipv4(struct __ctx_buff *ctx)
{
	int ret = CTX_ACT_OK;
	__s8 ext_err = 0;

	if (!ctx_skip_nodeport(ctx)) {
		int l3_off = ETH_HLEN;
		void *data, *data_end;
		struct iphdr *ip4;

		if (!revalidate_data(ctx, &data, &data_end, &ip4)) {
			ret = DROP_INVALID;
			goto out;
		}

#if defined(ENABLE_DSR) && DSR_ENCAP_MODE == DSR_ENCAP_GENEVE
		{
			int l4_off, inner_l2_off;
			struct genevehdr geneve;
			__sum16	udp_csum;
			__be16 dport;
			__u16 proto;

			if (ip4->protocol != IPPROTO_UDP)
				goto no_encap;

			/* Punt packets with IP options to TC */
			if (ipv4_hdrlen(ip4) != sizeof(*ip4))
				goto no_encap;

			l4_off = l3_off + sizeof(*ip4);

			if (l4_load_port(ctx, l4_off + UDP_DPORT_OFF, &dport) < 0) {
				ret = DROP_INVALID;
				goto out;
			}

			if (dport != bpf_htons(TUNNEL_PORT))
				goto no_encap;

			/* Cilium uses BPF_F_ZERO_CSUM_TX for its tunnel traffic.
			 *
			 * Adding LB support for checksummed packets would require
			 * that we adjust udp->check
			 * 1.	after DNAT of the inner packet,
			 * 2.	after re-writing the outer headers and inserting
			 *	the DSR option
			 */
			if (ctx_load_bytes(ctx, l4_off + offsetof(struct udphdr, check),
					   &udp_csum, sizeof(udp_csum)) < 0) {
				ret = DROP_INVALID;
				goto out;
			}

			if (udp_csum != 0)
				goto no_encap;

			if (ctx_load_bytes(ctx, l4_off + sizeof(struct udphdr), &geneve,
					   sizeof(geneve)) < 0) {
				ret = DROP_INVALID;
				goto out;
			}

			if (geneve.protocol_type != bpf_htons(ETH_P_TEB))
				goto no_encap;

			/* Punt packets with GENEVE options to TC */
			if (geneve.opt_len)
				goto no_encap;

			inner_l2_off = l4_off + sizeof(struct udphdr) + sizeof(struct genevehdr);

			/* point at the inner L3 header: */
			if (!validate_ethertype_l2_off(ctx, inner_l2_off, &proto))
				goto no_encap;

			if (proto != bpf_htons(ETH_P_IP))
				goto no_encap;

			l3_off = inner_l2_off + ETH_HLEN;

			if (!revalidate_data_l3_off(ctx, &data, &data_end, &ip4, l3_off)) {
				ret = DROP_INVALID;
				goto out;
			}
		}
no_encap:
#endif /* ENABLE_DSR && DSR_ENCAP_MODE == DSR_ENCAP_GENEVE */

		ret = nodeport_lb4(ctx, ip4, l3_off, 0, &ext_err);
		if (ret == NAT_46X64_RECIRC) {
			ep_tail_call(ctx, CILIUM_CALL_IPV6_FROM_NETDEV);
			return send_drop_notify_error(ctx, 0, DROP_MISSED_TAIL_CALL,
						      CTX_ACT_DROP, METRIC_INGRESS);
		}
	}

out:
	if (IS_ERR(ret))
		return send_drop_notify_error_ext(ctx, 0, ret, ext_err,
						  CTX_ACT_DROP, METRIC_INGRESS);

	return bpf_xdp_exit(ctx, ret);
}

static __always_inline int check_v4_lb(struct __ctx_buff *ctx)
{
	ep_tail_call(ctx, CILIUM_CALL_IPV4_FROM_NETDEV);
	return send_drop_notify_error(ctx, 0, DROP_MISSED_TAIL_CALL, CTX_ACT_DROP,
				      METRIC_INGRESS);
}
#else
static __always_inline int check_v4_lb(struct __ctx_buff *ctx __maybe_unused)
{
	return CTX_ACT_OK;
}
#endif /* ENABLE_NODEPORT_ACCELERATION */

#ifdef ENABLE_PREFILTER
static __always_inline int check_v4(struct __ctx_buff *ctx)
{
	void *data_end = ctx_data_end(ctx);
	void *data = ctx_data(ctx);
	struct iphdr *ipv4_hdr = data + sizeof(struct ethhdr);
	struct lpm_v4_key pfx __maybe_unused;

	if (ctx_no_room(ipv4_hdr + 1, data_end))
		return CTX_ACT_DROP;

#ifdef CIDR4_FILTER
	memcpy(pfx.lpm.data, &ipv4_hdr->saddr, sizeof(pfx.addr));
	pfx.lpm.prefixlen = 32;

#ifdef CIDR4_LPM_PREFILTER
	if (map_lookup_elem(&CIDR4_LMAP_NAME, &pfx))
		return CTX_ACT_DROP;
#endif /* CIDR4_LPM_PREFILTER */
	return map_lookup_elem(&CIDR4_HMAP_NAME, &pfx) ?
		CTX_ACT_DROP : check_v4_lb(ctx);
#else
	return check_v4_lb(ctx);
#endif /* CIDR4_FILTER */
}
#else
static __always_inline int check_v4(struct __ctx_buff *ctx)
{
	return check_v4_lb(ctx);
}
#endif /* ENABLE_PREFILTER */
#endif /* ENABLE_IPV4 */

#ifdef ENABLE_IPV6
#ifdef ENABLE_NODEPORT_ACCELERATION
__section_tail(CILIUM_MAP_CALLS, CILIUM_CALL_IPV6_FROM_NETDEV)
int tail_lb_ipv6(struct __ctx_buff *ctx)
{
	int ret = CTX_ACT_OK;
	__s8 ext_err = 0;

	if (!ctx_skip_nodeport(ctx)) {
		void *data, *data_end;
		struct ipv6hdr *ip6;

		if (!revalidate_data(ctx, &data, &data_end, &ip6)) {
			ret = DROP_INVALID;
			goto drop_err;
		}

		ret = nodeport_lb6(ctx, ip6, 0, &ext_err);
		if (IS_ERR(ret))
			goto drop_err;
	}

	return bpf_xdp_exit(ctx, ret);

drop_err:
	return send_drop_notify_error_ext(ctx, 0, ret, ext_err,
					  CTX_ACT_DROP, METRIC_INGRESS);
}

static __always_inline int check_v6_lb(struct __ctx_buff *ctx)
{
	ep_tail_call(ctx, CILIUM_CALL_IPV6_FROM_NETDEV);
	return send_drop_notify_error(ctx, 0, DROP_MISSED_TAIL_CALL, CTX_ACT_DROP,
				      METRIC_INGRESS);
}
#else
static __always_inline int check_v6_lb(struct __ctx_buff *ctx __maybe_unused)
{
	return CTX_ACT_OK;
}
#endif /* ENABLE_NODEPORT_ACCELERATION */

#ifdef ENABLE_PREFILTER
static __always_inline int check_v6(struct __ctx_buff *ctx)
{
	void *data_end = ctx_data_end(ctx);
	void *data = ctx_data(ctx);
	struct ipv6hdr *ipv6_hdr = data + sizeof(struct ethhdr);
	struct lpm_v6_key pfx __maybe_unused;

	if (ctx_no_room(ipv6_hdr + 1, data_end))
		return CTX_ACT_DROP;

#ifdef CIDR6_FILTER
	__bpf_memcpy_builtin(pfx.lpm.data, &ipv6_hdr->saddr, sizeof(pfx.addr));
	pfx.lpm.prefixlen = 128;

#ifdef CIDR6_LPM_PREFILTER
	if (map_lookup_elem(&CIDR6_LMAP_NAME, &pfx))
		return CTX_ACT_DROP;
#endif /* CIDR6_LPM_PREFILTER */
	return map_lookup_elem(&CIDR6_HMAP_NAME, &pfx) ?
		CTX_ACT_DROP : check_v6_lb(ctx);
#else
	return check_v6_lb(ctx);
#endif /* CIDR6_FILTER */
}
#else
static __always_inline int check_v6(struct __ctx_buff *ctx)
{
	return check_v6_lb(ctx);
}
#endif /* ENABLE_PREFILTER */
#endif /* ENABLE_IPV6 */

static __always_inline int check_filters(struct __ctx_buff *ctx)
{
	int ret = CTX_ACT_OK;
	__u16 proto;

	if (!validate_ethertype(ctx, &proto))
		return CTX_ACT_OK;

	ctx_store_meta(ctx, XFER_MARKER, 0);
	ctx_skip_nodeport_clear(ctx);

	switch (proto) {
#ifdef ENABLE_IPV4
	case bpf_htons(ETH_P_IP):
		ret = check_v4(ctx);
		break;
#endif /* ENABLE_IPV4 */
#ifdef ENABLE_IPV6
	case bpf_htons(ETH_P_IPV6):
		ret = check_v6(ctx);
		break;
#endif /* ENABLE_IPV6 */
	default:
		break;
	}

	return bpf_xdp_exit(ctx, ret);
}

__section_entry
int cil_xdp_entry(struct __ctx_buff *ctx)
{
	return check_filters(ctx);
}

BPF_LICENSE("Dual BSD/GPL");