/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2006 The FreeBSD Project.
 * Copyright (c) 2015 Andrey V. Elsukov <ae@FreeBSD.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "opt_inet.h"
#include "opt_inet6.h"
#include "opt_ipsec.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/hhook.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/module.h>
#include <machine/bus.h>
#include <sys/rman.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/sysctl.h>

#include <net/if.h>
#include <net/if_enc.h>
#include <net/if_var.h>
#include <net/if_private.h>
#include <net/if_clone.h>
#include <net/if_types.h>
#include <net/pfil.h>
#include <net/route.h>
#include <net/netisr.h>
#include <net/bpf.h>
#include <net/vnet.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/in_var.h>

#ifdef INET6
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#endif

#include <netipsec/ipsec.h>
#include <netipsec/xform.h>

#define ENCMTU          (1024+512)

/* XXX this define must have the same value as in OpenBSD */
#define M_CONF          0x0400  /* payload was encrypted (ESP-transport) */
#define M_AUTH          0x0800  /* payload was authenticated (AH or ESP auth) */
#define M_AUTH_AH       0x2000  /* header was authenticated (AH) */

struct enchdr {
        u_int32_t af;
        u_int32_t spi;
        u_int32_t flags;
};
struct enc_softc {
        struct  ifnet *sc_ifp;
};
VNET_DEFINE_STATIC(struct enc_softc *, enc_sc);
#define V_enc_sc        VNET(enc_sc)
VNET_DEFINE_STATIC(struct if_clone *, enc_cloner);
#define V_enc_cloner    VNET(enc_cloner)

static int      enc_ioctl(struct ifnet *, u_long, caddr_t);
static int      enc_output(struct ifnet *, struct mbuf *,
    const struct sockaddr *, struct route *);
static int      enc_clone_create(struct if_clone *, char *, size_t,
    struct ifc_data *, struct ifnet **);
static int      enc_clone_destroy(struct if_clone *, struct ifnet *, uint32_t);
static void     enc_add_hhooks(struct enc_softc *);
static void     enc_remove_hhooks(struct enc_softc *);

static const char encname[] = "enc";

#define IPSEC_ENC_AFTER_PFIL    0x04
/*
 * Before and after are relative to when we are stripping the
 * outer IP header.
 *
 * AFTER_PFIL flag used only for bpf_mask_*. It enables BPF capturing
 * after PFIL hook execution. It might be useful when PFIL hook does
 * some changes to the packet, e.g. address translation. If PFIL hook
 * consumes mbuf, nothing will be captured.
 */
VNET_DEFINE_STATIC(int, filter_mask_in) = IPSEC_ENC_BEFORE;
VNET_DEFINE_STATIC(int, bpf_mask_in) = IPSEC_ENC_BEFORE;
VNET_DEFINE_STATIC(int, filter_mask_out) = IPSEC_ENC_BEFORE;
VNET_DEFINE_STATIC(int, bpf_mask_out) = IPSEC_ENC_BEFORE | IPSEC_ENC_AFTER;
#define V_filter_mask_in        VNET(filter_mask_in)
#define V_bpf_mask_in           VNET(bpf_mask_in)
#define V_filter_mask_out       VNET(filter_mask_out)
#define V_bpf_mask_out          VNET(bpf_mask_out)

static SYSCTL_NODE(_net, OID_AUTO, enc, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
    "enc sysctl");
static SYSCTL_NODE(_net_enc, OID_AUTO, in, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
    "enc input sysctl");
static SYSCTL_NODE(_net_enc, OID_AUTO, out, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
    "enc output sysctl");
SYSCTL_INT(_net_enc_in, OID_AUTO, ipsec_filter_mask,
    CTLFLAG_RW | CTLFLAG_VNET, &VNET_NAME(filter_mask_in), 0,
    "IPsec input firewall filter mask");
SYSCTL_INT(_net_enc_in, OID_AUTO, ipsec_bpf_mask,
    CTLFLAG_RW | CTLFLAG_VNET, &VNET_NAME(bpf_mask_in), 0,
    "IPsec input bpf mask");
SYSCTL_INT(_net_enc_out, OID_AUTO, ipsec_filter_mask,
    CTLFLAG_RW | CTLFLAG_VNET, &VNET_NAME(filter_mask_out), 0,
    "IPsec output firewall filter mask");
SYSCTL_INT(_net_enc_out, OID_AUTO, ipsec_bpf_mask,
    CTLFLAG_RW | CTLFLAG_VNET, &VNET_NAME(bpf_mask_out), 0,
    "IPsec output bpf mask");

static int
enc_clone_destroy(struct if_clone *ifc, struct ifnet *ifp, uint32_t flags)
{
        struct enc_softc *sc;

        if (ifp->if_dunit == 0 && (flags & IFC_F_FORCE) == 0)
                return (EINVAL);

        sc = ifp->if_softc;
        KASSERT(sc == V_enc_sc, ("sc != ifp->if_softc"));

        bpfdetach(ifp);
        if_detach(ifp);
        if_free(ifp);
        free(sc, M_DEVBUF);
        return (0);
}

static int
enc_clone_create(struct if_clone *ifc, char *name, size_t len,
    struct ifc_data *ifd, struct ifnet **ifpp)
{
        struct ifnet *ifp;
        struct enc_softc *sc;

        sc = malloc(sizeof(struct enc_softc), M_DEVBUF, M_WAITOK | M_ZERO);
        ifp = sc->sc_ifp = if_alloc(IFT_ENC);
        if_initname(ifp, encname, ifd->unit);
        ifp->if_mtu = ENCMTU;
        ifp->if_ioctl = enc_ioctl;
        ifp->if_output = enc_output;
        ifp->if_softc = sc;
        if_attach(ifp);
        bpfattach(ifp, DLT_ENC, sizeof(struct enchdr));
        *ifpp = ifp;
        return (0);
}

static int
enc_output(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *dst,
    struct route *ro)
{

        m_freem(m);
        return (0);
}

static int
enc_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
{

        if (cmd != SIOCSIFFLAGS)
                return (EINVAL);
        if (ifp->if_flags & IFF_UP)
                ifp->if_drv_flags |= IFF_DRV_RUNNING;
        else
                ifp->if_drv_flags &= ~IFF_DRV_RUNNING;
        return (0);
}

static void
enc_bpftap(struct ifnet *ifp, struct mbuf *m, const struct secasvar *sav,
    int32_t hhook_type, uint8_t enc, uint8_t af)
{
        struct enchdr hdr;

        if (hhook_type == HHOOK_TYPE_IPSEC_IN &&
            (enc & V_bpf_mask_in) == 0)
                return;
        else if (hhook_type == HHOOK_TYPE_IPSEC_OUT &&
            (enc & V_bpf_mask_out) == 0)
                return;
        if (!bpf_peers_present(ifp->if_bpf))
                return;
        hdr.af = af;
        hdr.spi = sav->spi;
        hdr.flags = 0;
        if (sav->alg_enc != SADB_EALG_NONE)
                hdr.flags |= M_CONF;
        if (sav->alg_auth != SADB_AALG_NONE)
                hdr.flags |= M_AUTH;
        bpf_mtap2(ifp->if_bpf, &hdr, sizeof(hdr), m);
}

/*
 * One helper hook function is used by any hook points.
 * + from hhook_type we can determine the packet direction:
 *   HHOOK_TYPE_IPSEC_IN or HHOOK_TYPE_IPSEC_OUT;
 * + from hhook_id we can determine address family: AF_INET or AF_INET6;
 * + udata contains pointer to enc_softc;
 * + ctx_data contains pointer to struct ipsec_ctx_data.
 */
static int
enc_hhook(int32_t hhook_type, int32_t hhook_id, void *udata, void *ctx_data,
    void *hdata, struct osd *hosd)
{
        struct ipsec_ctx_data *ctx;
        struct enc_softc *sc;
        struct ifnet *ifp, *rcvif;
        struct pfil_head *ph;
        int pdir, ret;

        sc = (struct enc_softc *)udata;
        ifp = sc->sc_ifp;
        if ((ifp->if_flags & IFF_UP) == 0)
                return (0);

        ctx = (struct ipsec_ctx_data *)ctx_data;
        /* XXX: wrong hook point was used by caller? */
        if (ctx->af != hhook_id)
                return (EPFNOSUPPORT);

        enc_bpftap(ifp, *ctx->mp, ctx->sav, hhook_type, ctx->enc, ctx->af);
        switch (hhook_type) {
        case HHOOK_TYPE_IPSEC_IN:
                if (ctx->enc == IPSEC_ENC_BEFORE) {
                        /* Do accounting only once */
                        if_inc_counter(ifp, IFCOUNTER_IPACKETS, 1);
                        if_inc_counter(ifp, IFCOUNTER_IBYTES,
                            (*ctx->mp)->m_pkthdr.len);
                }
                if ((ctx->enc & V_filter_mask_in) == 0)
                        return (0); /* skip pfil processing */
                pdir = PFIL_IN;
                break;
        case HHOOK_TYPE_IPSEC_OUT:
                if (ctx->enc == IPSEC_ENC_BEFORE) {
                        /* Do accounting only once */
                        if_inc_counter(ifp, IFCOUNTER_OPACKETS, 1);
                        if_inc_counter(ifp, IFCOUNTER_OBYTES,
                            (*ctx->mp)->m_pkthdr.len);
                }
                if ((ctx->enc & V_filter_mask_out) == 0)
                        return (0); /* skip pfil processing */
                pdir = PFIL_OUT;
                break;
        default:
                return (EINVAL);
        }

        switch (hhook_id) {
#ifdef INET
        case AF_INET:
                ph = V_inet_pfil_head;
                break;
#endif
#ifdef INET6
        case AF_INET6:
                ph = V_inet6_pfil_head;
                break;
#endif
        default:
                ph = NULL;
        }
        if (ph == NULL || (pdir == PFIL_OUT && !PFIL_HOOKED_OUT(ph)) ||
            (pdir == PFIL_IN && !PFIL_HOOKED_IN(ph)))
                return (0);
        /* Make a packet looks like it was received on enc(4) */
        rcvif = (*ctx->mp)->m_pkthdr.rcvif;
        (*ctx->mp)->m_pkthdr.rcvif = ifp;
        if (pdir == PFIL_IN)
                ret = pfil_mbuf_in(ph, ctx->mp, ifp, ctx->inp);
        else
                ret = pfil_mbuf_out(ph, ctx->mp, ifp, ctx->inp);
        if (ret != PFIL_PASS) {
                *ctx->mp = NULL; /* consumed by filter */
                return (EACCES);
        }
        (*ctx->mp)->m_pkthdr.rcvif = rcvif;
        enc_bpftap(ifp, *ctx->mp, ctx->sav, hhook_type,
            IPSEC_ENC_AFTER_PFIL, ctx->af);
        return (0);
}

static void
enc_add_hhooks(struct enc_softc *sc)
{
        struct hookinfo hki;
        int error __diagused;

        hki.hook_func = enc_hhook;
        hki.hook_helper = NULL;
        hki.hook_udata = sc;
#ifdef INET
        hki.hook_id = AF_INET;
        hki.hook_type = HHOOK_TYPE_IPSEC_IN;
        error = hhook_add_hook(V_ipsec_hhh_in[HHOOK_IPSEC_INET],
            &hki, HHOOK_WAITOK);
        MPASS(error == 0);
        hki.hook_type = HHOOK_TYPE_IPSEC_OUT;
        error = hhook_add_hook(V_ipsec_hhh_out[HHOOK_IPSEC_INET],
            &hki, HHOOK_WAITOK);
        MPASS(error == 0);
#endif
#ifdef INET6
        hki.hook_id = AF_INET6;
        hki.hook_type = HHOOK_TYPE_IPSEC_IN;
        error = hhook_add_hook(V_ipsec_hhh_in[HHOOK_IPSEC_INET6],
            &hki, HHOOK_WAITOK);
        MPASS(error == 0);
        hki.hook_type = HHOOK_TYPE_IPSEC_OUT;
        error = hhook_add_hook(V_ipsec_hhh_out[HHOOK_IPSEC_INET6],
            &hki, HHOOK_WAITOK);
        MPASS(error == 0);
#endif
}

static void
enc_remove_hhooks(struct enc_softc *sc)
{
        struct hookinfo hki;

        hki.hook_func = enc_hhook;
        hki.hook_helper = NULL;
        hki.hook_udata = sc;
#ifdef INET
        hki.hook_id = AF_INET;
        hki.hook_type = HHOOK_TYPE_IPSEC_IN;
        hhook_remove_hook(V_ipsec_hhh_in[HHOOK_IPSEC_INET], &hki);
        hki.hook_type = HHOOK_TYPE_IPSEC_OUT;
        hhook_remove_hook(V_ipsec_hhh_out[HHOOK_IPSEC_INET], &hki);
#endif
#ifdef INET6
        hki.hook_id = AF_INET6;
        hki.hook_type = HHOOK_TYPE_IPSEC_IN;
        hhook_remove_hook(V_ipsec_hhh_in[HHOOK_IPSEC_INET6], &hki);
        hki.hook_type = HHOOK_TYPE_IPSEC_OUT;
        hhook_remove_hook(V_ipsec_hhh_out[HHOOK_IPSEC_INET6], &hki);
#endif
}

static void
vnet_enc_init(const void *unused __unused)
{
        struct ifnet *ifp;

        struct if_clone_addreq req = {
                .create_f = enc_clone_create,
                .destroy_f = enc_clone_destroy,
                .flags = IFC_F_AUTOUNIT | IFC_F_LIMITUNIT,
                .maxunit = 0,
        };
        V_enc_cloner = ifc_attach_cloner(encname, &req);
        struct ifc_data ifd = { .unit = 0 };
        ifc_create_ifp(encname, &ifd, &ifp);
        V_enc_sc = ifp->if_softc;
}
VNET_SYSINIT(vnet_enc_init, SI_SUB_PROTO_IF, SI_ORDER_ANY,
    vnet_enc_init, NULL);

static void
vnet_enc_init_proto(void *unused __unused)
{
        KASSERT(V_enc_sc != NULL, ("%s: V_enc_sc is %p\n", __func__, V_enc_sc));

        enc_add_hhooks(V_enc_sc);
}
VNET_SYSINIT(vnet_enc_init_proto, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY,
    vnet_enc_init_proto, NULL);

static void
vnet_enc_uninit(const void *unused __unused)
{
        KASSERT(V_enc_sc != NULL, ("%s: V_enc_sc is %p\n", __func__, V_enc_sc));

        ifc_detach_cloner(V_enc_cloner);
        V_enc_sc = NULL;
}
VNET_SYSUNINIT(vnet_enc_uninit, SI_SUB_INIT_IF, SI_ORDER_ANY,
    vnet_enc_uninit, NULL);

/*
 * The hhook consumer needs to go before ip[6]_destroy are called on
 * SI_ORDER_THIRD.
 */
static void
vnet_enc_uninit_hhook(const void *unused __unused)
{
        KASSERT(V_enc_sc != NULL, ("%s: V_enc_sc is %p\n", __func__, V_enc_sc));

        enc_remove_hhooks(V_enc_sc);
}
VNET_SYSUNINIT(vnet_enc_uninit_hhook, SI_SUB_PROTO_DOMAIN, SI_ORDER_FOURTH,
    vnet_enc_uninit_hhook, NULL);

static int
enc_modevent(module_t mod, int type, void *data)
{

        switch (type) {
        case MOD_LOAD:
        case MOD_UNLOAD:
                break;
        default:
                return (EOPNOTSUPP);
        }
        return (0);
}

static moduledata_t enc_mod = {
        "if_enc",
        enc_modevent,
        0
};

DECLARE_MODULE(if_enc, enc_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
MODULE_VERSION(if_enc, 1);