// SPDX-License-Identifier: GPL-2.0
/*
 * xfrm6_state.c: based on xfrm4_state.c
 *
 * Authors:
 *	Mitsuru KANDA @USAGI
 *	Kazunori MIYAZAWA @USAGI
 *	Kunihiro Ishiguro <kunihiro@ipinfusion.com>
 *		IPv6 support
 *	YOSHIFUJI Hideaki @USAGI
 *		Split up af-specific portion
 *
 */

#include <net/xfrm.h>
#include <linux/pfkeyv2.h>
#include <linux/ipsec.h>
#include <linux/netfilter_ipv6.h>
#include <linux/export.h>
#include <net/dsfield.h>
#include <net/ipv6.h>
#include <net/addrconf.h>

static void
__xfrm6_init_tempsel(struct xfrm_selector *sel, const struct flowi *fl)
{
	const struct flowi6 *fl6 = &fl->u.ip6;

	/* Initialize temporary selector matching only
	 * to current session. */
	*(struct in6_addr *)&sel->daddr = fl6->daddr;
	*(struct in6_addr *)&sel->saddr = fl6->saddr;
	sel->dport = xfrm_flowi_dport(fl, &fl6->uli);
	sel->dport_mask = htons(0xffff);
	sel->sport = xfrm_flowi_sport(fl, &fl6->uli);
	sel->sport_mask = htons(0xffff);
	sel->family = AF_INET6;
	sel->prefixlen_d = 128;
	sel->prefixlen_s = 128;
	sel->proto = fl6->flowi6_proto;
	sel->ifindex = fl6->flowi6_oif;
}

static void
xfrm6_init_temprop(struct xfrm_state *x, const struct xfrm_tmpl *tmpl,
		   const xfrm_address_t *daddr, const xfrm_address_t *saddr)
{
	x->id = tmpl->id;
	if (ipv6_addr_any((struct in6_addr *)&x->id.daddr))
		memcpy(&x->id.daddr, daddr, sizeof(x->sel.daddr));
	memcpy(&x->props.saddr, &tmpl->saddr, sizeof(x->props.saddr));
	if (ipv6_addr_any((struct in6_addr *)&x->props.saddr))
		memcpy(&x->props.saddr, saddr, sizeof(x->props.saddr));
	x->props.mode = tmpl->mode;
	x->props.reqid = tmpl->reqid;
	x->props.family = AF_INET6;
}

/* distribution counting sort function for xfrm_state and xfrm_tmpl */
static int
__xfrm6_sort(void **dst, void **src, int n, int (*cmp)(void *p), int maxclass)
{
	int count[XFRM_MAX_DEPTH] = { };
	int class[XFRM_MAX_DEPTH];
	int i;

	for (i = 0; i < n; i++) {
		int c;
		class[i] = c = cmp(src[i]);
		count[c]++;
	}

	for (i = 2; i < maxclass; i++)
		count[i] += count[i - 1];

	for (i = 0; i < n; i++) {
		dst[count[class[i] - 1]++] = src[i];
		src[i] = NULL;
	}

	return 0;
}

/*
 * Rule for xfrm_state:
 *
 * rule 1: select IPsec transport except AH
 * rule 2: select MIPv6 RO or inbound trigger
 * rule 3: select IPsec transport AH
 * rule 4: select IPsec tunnel
 * rule 5: others
 */
static int __xfrm6_state_sort_cmp(void *p)
{
	struct xfrm_state *v = p;

	switch (v->props.mode) {
	case XFRM_MODE_TRANSPORT:
		if (v->id.proto != IPPROTO_AH)
			return 1;
		else
			return 3;
#if IS_ENABLED(CONFIG_IPV6_MIP6)
	case XFRM_MODE_ROUTEOPTIMIZATION:
	case XFRM_MODE_IN_TRIGGER:
		return 2;
#endif
	case XFRM_MODE_TUNNEL:
	case XFRM_MODE_BEET:
		return 4;
	}
	return 5;
}

static int
__xfrm6_state_sort(struct xfrm_state **dst, struct xfrm_state **src, int n)
{
	return __xfrm6_sort((void **)dst, (void **)src, n,
			    __xfrm6_state_sort_cmp, 6);
}

/*
 * Rule for xfrm_tmpl:
 *
 * rule 1: select IPsec transport
 * rule 2: select MIPv6 RO or inbound trigger
 * rule 3: select IPsec tunnel
 * rule 4: others
 */
static int __xfrm6_tmpl_sort_cmp(void *p)
{
	struct xfrm_tmpl *v = p;
	switch (v->mode) {
	case XFRM_MODE_TRANSPORT:
		return 1;
#if IS_ENABLED(CONFIG_IPV6_MIP6)
	case XFRM_MODE_ROUTEOPTIMIZATION:
	case XFRM_MODE_IN_TRIGGER:
		return 2;
#endif
	case XFRM_MODE_TUNNEL:
	case XFRM_MODE_BEET:
		return 3;
	}
	return 4;
}

static int
__xfrm6_tmpl_sort(struct xfrm_tmpl **dst, struct xfrm_tmpl **src, int n)
{
	return __xfrm6_sort((void **)dst, (void **)src, n,
			    __xfrm6_tmpl_sort_cmp, 5);
}

int xfrm6_extract_header(struct sk_buff *skb)
{
	struct ipv6hdr *iph = ipv6_hdr(skb);

	XFRM_MODE_SKB_CB(skb)->ihl = sizeof(*iph);
	XFRM_MODE_SKB_CB(skb)->id = 0;
	XFRM_MODE_SKB_CB(skb)->frag_off = htons(IP_DF);
	XFRM_MODE_SKB_CB(skb)->tos = ipv6_get_dsfield(iph);
	XFRM_MODE_SKB_CB(skb)->ttl = iph->hop_limit;
	XFRM_MODE_SKB_CB(skb)->optlen = 0;
	memcpy(XFRM_MODE_SKB_CB(skb)->flow_lbl, iph->flow_lbl,
	       sizeof(XFRM_MODE_SKB_CB(skb)->flow_lbl));

	return 0;
}

static struct xfrm_state_afinfo xfrm6_state_afinfo = {
	.family			= AF_INET6,
	.proto			= IPPROTO_IPV6,
	.eth_proto		= htons(ETH_P_IPV6),
	.owner			= THIS_MODULE,
	.init_tempsel		= __xfrm6_init_tempsel,
	.init_temprop		= xfrm6_init_temprop,
	.tmpl_sort		= __xfrm6_tmpl_sort,
	.state_sort		= __xfrm6_state_sort,
	.output			= xfrm6_output,
	.output_finish		= xfrm6_output_finish,
	.extract_input		= xfrm6_extract_input,
	.extract_output		= xfrm6_extract_output,
	.transport_finish	= xfrm6_transport_finish,
	.local_error		= xfrm6_local_error,
};

int __init xfrm6_state_init(void)
{
	return xfrm_state_register_afinfo(&xfrm6_state_afinfo);
}

void xfrm6_state_fini(void)
{
	xfrm_state_unregister_afinfo(&xfrm6_state_afinfo);
}