// 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 i;
        int class[XFRM_MAX_DEPTH];
        int count[maxclass];

        memset(count, 0, sizeof(count));

        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);
}