/*-
* Copyright (c) 2009-2013 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This material is based upon work partially supported by The
* NetBSD Foundation under a contract with Mindaugas Rasiukevicius.
*
* 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/

/*
* NPF byte-code processing.
*/

#ifdef _KERNEL
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: npf_bpf.c,v 1.14 2018/09/29 14:41:36 rmind Exp $");

#include <sys/types.h>
#include <sys/param.h>

#include <sys/bitops.h>
#include <sys/mbuf.h>
#include <net/bpf.h>
#endif

#define NPF_BPFCOP
#include "npf_impl.h"

#if defined(_NPF_STANDALONE)
#define m_length(m)             (nbuf)->nb_mops->getchainlen(m)
#endif

/*
* BPF context and the coprocessor.
*/

static bpf_ctx_t *npf_bpfctx __read_mostly;

static uint32_t npf_cop_l3(const bpf_ctx_t *, bpf_args_t *, uint32_t);
static uint32_t npf_cop_table(const bpf_ctx_t *, bpf_args_t *, uint32_t);

static const bpf_copfunc_t npf_bpfcop[] = {
       [NPF_COP_L3]    = npf_cop_l3,
       [NPF_COP_TABLE] = npf_cop_table,
};

#define BPF_MW_ALLMASK \
   ((1U << BPF_MW_IPVER) | (1U << BPF_MW_L4OFF) | (1U << BPF_MW_L4PROTO))

void
npf_bpf_sysinit(void)
{
       npf_bpfctx = bpf_create();
       bpf_set_cop(npf_bpfctx, npf_bpfcop, __arraycount(npf_bpfcop));
       bpf_set_extmem(npf_bpfctx, NPF_BPF_NWORDS, BPF_MW_ALLMASK);
}

void
npf_bpf_sysfini(void)
{
       bpf_destroy(npf_bpfctx);
}

void
npf_bpf_prepare(npf_cache_t *npc, bpf_args_t *args, uint32_t *M)
{
       nbuf_t *nbuf = npc->npc_nbuf;
       const struct mbuf *mbuf = nbuf_head_mbuf(nbuf);
       const size_t pktlen = m_length(mbuf);

       /* Prepare the arguments for the BPF programs. */
#ifdef _NPF_STANDALONE
       args->pkt = (const uint8_t *)nbuf_dataptr(nbuf);
       args->wirelen = args->buflen = pktlen;
#else
       args->pkt = (const uint8_t *)mbuf;
       args->wirelen = pktlen;
       args->buflen = 0;
#endif
       args->mem = M;
       args->arg = npc;

       /*
        * Convert address length to IP version.  Just mask out
        * number 4 or set 6 if higher bits set, such that:
        *
        *      0       =>      0
        *      4       =>      4 (IPVERSION)
        *      16      =>      6 (IPV6_VERSION >> 4)
        */
       const u_int alen = npc->npc_alen;
       const uint32_t ver = (alen & 4) | ((alen >> 4) * 6);

       /*
        * Output words in the memory store:
        *      BPF_MW_IPVER    IP version (4 or 6).
        *      BPF_MW_L4OFF    L4 header offset.
        *      BPF_MW_L4PROTO  L4 protocol.
        */
       M[BPF_MW_IPVER] = ver;
       M[BPF_MW_L4OFF] = npc->npc_hlen;
       M[BPF_MW_L4PROTO] = npc->npc_proto;
}

int
npf_bpf_filter(bpf_args_t *args, const void *code, bpfjit_func_t jcode)
{
       /* Execute JIT-compiled code. */
       if (__predict_true(jcode)) {
               return jcode(npf_bpfctx, args);
       }

       /* Execute BPF byte-code. */
       return bpf_filter_ext(npf_bpfctx, code, args);
}

void *
npf_bpf_compile(void *code, size_t size)
{
       return bpf_jit_generate(npf_bpfctx, code, size);
}

bool
npf_bpf_validate(const void *code, size_t len)
{
       const size_t icount = len / sizeof(struct bpf_insn);
       return bpf_validate_ext(npf_bpfctx, code, icount) != 0;
}

/*
* NPF_COP_L3: fetches layer 3 information.
*/
static uint32_t
npf_cop_l3(const bpf_ctx_t *bc, bpf_args_t *args, uint32_t A)
{
       const npf_cache_t * const npc = (const npf_cache_t *)args->arg;
       const uint32_t ver = (npc->npc_alen & 4) | ((npc->npc_alen >> 4) * 6);
       uint32_t * const M = args->mem;

       M[BPF_MW_IPVER] = ver;
       M[BPF_MW_L4OFF] = npc->npc_hlen;
       M[BPF_MW_L4PROTO] = npc->npc_proto;
       return ver; /* A <- IP version */
}

#define SRC_FLAG_BIT    (1U << 31)

/*
* NPF_COP_TABLE: perform NPF table lookup.
*
*      A <- non-zero (true) if found and zero (false) otherwise
*/
static uint32_t
npf_cop_table(const bpf_ctx_t *bc, bpf_args_t *args, uint32_t A)
{
       const npf_cache_t * const npc = (const npf_cache_t *)args->arg;
       npf_tableset_t *tblset = npf_config_tableset(npc->npc_ctx);
       const uint32_t tid = A & (SRC_FLAG_BIT - 1);
       const npf_addr_t *addr;
       npf_table_t *t;

       if (!npf_iscached(npc, NPC_IP46)) {
               return 0;
       }
       t = npf_tableset_getbyid(tblset, tid);
       if (__predict_false(!t)) {
               return 0;
       }
       addr = npc->npc_ips[(A & SRC_FLAG_BIT) ? NPF_SRC : NPF_DST];
       return npf_table_lookup(t, npc->npc_alen, addr) == 0;
}

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