/*-
 * Copyright (c) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
 *	The Regents of the University of California.  All rights reserved.
 *
 * Some Portions Copyright (C) 2014 Cisco and/or its affiliates. All rights reserved.
 * Some portions Copyright (C) 2010-2013 Sourcefire, Inc.
 *
 * This code is derived from the Stanford/CMU enet packet filter,
 * (net/enet.c) distributed as part of 4.3BSD, and code contributed
 * to Berkeley by Steven McCanne and Van Jacobson both of Lawrence
 * Berkeley Laboratory.
 *
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 *
 *	@(#)bpf.c	7.5 (Berkeley) 7/15/91
 */

#if !(defined(lint) || defined(KERNEL) || defined(_KERNEL))
static const char rcsid[] =
    "@(#) $Header: //depot/firepower/daq-opensource/DAQ_2_0_7/sfbpf/sf_bpf_filter.c#1 $ (LBL)";
#endif

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#ifdef WIN32

#include "win32-stdinc.h"

#else /* WIN32 */

#if HAVE_INTTYPES_H
#include <inttypes.h>
#elif HAVE_STDINT_H
#include <stdint.h>
#endif
#ifdef HAVE_SYS_BITYPES_H
#include <sys/bitypes.h>
#endif

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

#define	SOLARIS	(defined(sun) && (defined(__SVR4) || defined(__svr4__)))
#if defined(__hpux) || SOLARIS
# include <sys/sysmacros.h>
# include <sys/stream.h>
# define	mbuf	msgb
# define	m_next	b_cont
# define	MLEN(m)	((m)->b_wptr - (m)->b_rptr)
# define	mtod(m,t)	((t)(m)->b_rptr)
#else /* defined(__hpux) || SOLARIS */
# define	MLEN(m)	((m)->m_len)
#endif /* defined(__hpux) || SOLARIS */

#endif /* WIN32 */

#include "sfbpf-int.h"

#if !defined(KERNEL) && !defined(_KERNEL)
#include <stdlib.h>
#endif

#define int32 bpf_int32
#define u_int32 bpf_u_int32

#ifndef LBL_ALIGN
/*
 * XXX - IA-64?  If not, this probably won't work on Win64 IA-64
 * systems, unless LBL_ALIGN is defined elsewhere for them.
 * XXX - SuperH?  If not, this probably won't work on WinCE SuperH
 * systems, unless LBL_ALIGN is defined elsewhere for them.
 */
#if defined(sparc) || defined(__sparc__) || defined(mips) || \
    defined(ibm032) || defined(__alpha) || defined(__hpux) || \
    defined(__arm__)
#define LBL_ALIGN
#endif
#endif

#ifndef LBL_ALIGN
#ifndef WIN32
#include <netinet/in.h>
#endif

#define EXTRACT_SHORT(p)	((u_short)ntohs(*(u_short *)p))
#define EXTRACT_LONG(p)		(ntohl(*(u_int32 *)p))
#else
#define EXTRACT_SHORT(p)\
	((u_short)\
		((u_short)*((u_char *)p+0)<<8|\
		 (u_short)*((u_char *)p+1)<<0))
#define EXTRACT_LONG(p)\
		((u_int32)*((u_char *)p+0)<<24|\
		 (u_int32)*((u_char *)p+1)<<16|\
		 (u_int32)*((u_char *)p+2)<<8|\
		 (u_int32)*((u_char *)p+3)<<0)
#endif

#if defined(KERNEL) || defined(_KERNEL)
# if !defined(__hpux) && !SOLARIS
#include <sys/mbuf.h>
# endif
#define MINDEX(len, _m, _k) \
{ \
	len = MLEN(m); \
	while ((_k) >= len) { \
		(_k) -= len; \
		(_m) = (_m)->m_next; \
		if ((_m) == 0) \
			return 0; \
		len = MLEN(m); \
	} \
}

static int m_xword(m, k, err)
     register struct mbuf *m;
     register int k, *err;
{
    register int len;
    register u_char *cp, *np;
    register struct mbuf *m0;

    MINDEX(len, m, k);
    cp = mtod(m, u_char *) + k;
    if (len - k >= 4)
    {
        *err = 0;
        return EXTRACT_LONG(cp);
    }
    m0 = m->m_next;
    if (m0 == 0 || MLEN(m0) + len - k < 4)
        goto bad;
    *err = 0;
    np = mtod(m0, u_char *);
    switch (len - k)
    {

        case 1:
            return (cp[0] << 24) | (np[0] << 16) | (np[1] << 8) | np[2];

        case 2:
            return (cp[0] << 24) | (cp[1] << 16) | (np[0] << 8) | np[1];

        default:
            return (cp[0] << 24) | (cp[1] << 16) | (cp[2] << 8) | np[0];
    }
  bad:
    *err = 1;
    return 0;
}

static int m_xhalf(m, k, err)
     register struct mbuf *m;
     register int k, *err;
{
    register int len;
    register u_char *cp;
    register struct mbuf *m0;

    MINDEX(len, m, k);
    cp = mtod(m, u_char *) + k;
    if (len - k >= 2)
    {
        *err = 0;
        return EXTRACT_SHORT(cp);
    }
    m0 = m->m_next;
    if (m0 == 0)
        goto bad;
    *err = 0;
    return (cp[0] << 8) | mtod(m0, u_char *)[0];
  bad:
    *err = 1;
    return 0;
}
#endif

/*
 * Execute the filter program starting at pc on the packet p
 * wirelen is the length of the original packet
 * buflen is the amount of data present
 * For the kernel, p is assumed to be a pointer to an mbuf if buflen is 0,
 * in all other cases, p is a pointer to a buffer and buflen is its size.
 */
DAQ_SO_PUBLIC u_int bpf_filter(pc, p, wirelen, buflen)
     register const struct bpf_insn *pc;
     register const u_char *p;
     u_int wirelen;
     register u_int buflen;
{
    register u_int32 A, X;
    register int k;
    int32 mem[BPF_MEMWORDS];
#if defined(KERNEL) || defined(_KERNEL)
    struct mbuf *m, *n;
    int merr, len;

    if (buflen == 0)
    {
        m = (struct mbuf *) p;
        p = mtod(m, u_char *);
        buflen = MLEN(m);
    }
    else
        m = NULL;
#endif

    if (pc == 0)
        /*
         * No filter means accept all.
         */
        return (u_int) - 1;
    A = 0;
    X = 0;
    --pc;
    while (1)
    {
        ++pc;
        switch (pc->code)
        {

            default:
#if defined(KERNEL) || defined(_KERNEL)
                return 0;
#else
                abort();
#endif
            case BPF_RET | BPF_K:
                return (u_int) pc->k;

            case BPF_RET | BPF_A:
                return (u_int) A;

            case BPF_LD | BPF_W | BPF_ABS:
                k = pc->k;
                if (k + sizeof(int32) > buflen)
                {
#if defined(KERNEL) || defined(_KERNEL)
                    if (m == NULL)
                        return 0;
                    A = m_xword(m, k, &merr);
                    if (merr != 0)
                        return 0;
                    continue;
#else
                    return 0;
#endif
                }
                A = EXTRACT_LONG(&p[k]);
                continue;

            case BPF_LD | BPF_H | BPF_ABS:
                k = pc->k;
                if (k + sizeof(short) > buflen)
                {
#if defined(KERNEL) || defined(_KERNEL)
                    if (m == NULL)
                        return 0;
                    A = m_xhalf(m, k, &merr);
                    if (merr != 0)
                        return 0;
                    continue;
#else
                    return 0;
#endif
                }
                A = EXTRACT_SHORT(&p[k]);
                continue;

            case BPF_LD | BPF_B | BPF_ABS:
                k = pc->k;
                if (k >= buflen)
                {
#if defined(KERNEL) || defined(_KERNEL)
                    if (m == NULL)
                        return 0;
                    n = m;
                    MINDEX(len, n, k);
                    A = mtod(n, u_char *)[k];
                    continue;
#else
                    return 0;
#endif
                }
                A = p[k];
                continue;

            case BPF_LD | BPF_W | BPF_LEN:
                A = wirelen;
                continue;

            case BPF_LDX | BPF_W | BPF_LEN:
                X = wirelen;
                continue;

            case BPF_LD | BPF_W | BPF_IND:
                k = X + pc->k;
                if (k + sizeof(int32) > buflen)
                {
#if defined(KERNEL) || defined(_KERNEL)
                    if (m == NULL)
                        return 0;
                    A = m_xword(m, k, &merr);
                    if (merr != 0)
                        return 0;
                    continue;
#else
                    return 0;
#endif
                }
                A = EXTRACT_LONG(&p[k]);
                continue;

            case BPF_LD | BPF_H | BPF_IND:
                k = X + pc->k;
                if (k + sizeof(short) > buflen)
                {
#if defined(KERNEL) || defined(_KERNEL)
                    if (m == NULL)
                        return 0;
                    A = m_xhalf(m, k, &merr);
                    if (merr != 0)
                        return 0;
                    continue;
#else
                    return 0;
#endif
                }
                A = EXTRACT_SHORT(&p[k]);
                continue;

            case BPF_LD | BPF_B | BPF_IND:
                k = X + pc->k;
                if (k >= buflen)
                {
#if defined(KERNEL) || defined(_KERNEL)
                    if (m == NULL)
                        return 0;
                    n = m;
                    MINDEX(len, n, k);
                    A = mtod(n, u_char *)[k];
                    continue;
#else
                    return 0;
#endif
                }
                A = p[k];
                continue;

            case BPF_LDX | BPF_MSH | BPF_B:
                k = pc->k;
                if (k >= buflen)
                {
#if defined(KERNEL) || defined(_KERNEL)
                    if (m == NULL)
                        return 0;
                    n = m;
                    MINDEX(len, n, k);
                    X = (mtod(n, char *)[k] & 0xf) << 2;
                    continue;
#else
                    return 0;
#endif
                }
                X = (p[pc->k] & 0xf) << 2;
                continue;

            case BPF_LD | BPF_IMM:
                A = pc->k;
                continue;

            case BPF_LDX | BPF_IMM:
                X = pc->k;
                continue;

            case BPF_LD | BPF_MEM:
                A = mem[pc->k];
                continue;

            case BPF_LDX | BPF_MEM:
                X = mem[pc->k];
                continue;

            case BPF_ST:
                mem[pc->k] = A;
                continue;

            case BPF_STX:
                mem[pc->k] = X;
                continue;

            case BPF_JMP | BPF_JA:
                pc += pc->k;
                continue;

            case BPF_JMP | BPF_JGT | BPF_K:
                pc += (A > pc->k) ? pc->jt : pc->jf;
                continue;

            case BPF_JMP | BPF_JGE | BPF_K:
                pc += (A >= pc->k) ? pc->jt : pc->jf;
                continue;

            case BPF_JMP | BPF_JEQ | BPF_K:
                pc += (A == pc->k) ? pc->jt : pc->jf;
                continue;

            case BPF_JMP | BPF_JSET | BPF_K:
                pc += (A & pc->k) ? pc->jt : pc->jf;
                continue;

            case BPF_JMP | BPF_JGT | BPF_X:
                pc += (A > X) ? pc->jt : pc->jf;
                continue;

            case BPF_JMP | BPF_JGE | BPF_X:
                pc += (A >= X) ? pc->jt : pc->jf;
                continue;

            case BPF_JMP | BPF_JEQ | BPF_X:
                pc += (A == X) ? pc->jt : pc->jf;
                continue;

            case BPF_JMP | BPF_JSET | BPF_X:
                pc += (A & X) ? pc->jt : pc->jf;
                continue;

            case BPF_ALU | BPF_ADD | BPF_X:
                A += X;
                continue;

            case BPF_ALU | BPF_SUB | BPF_X:
                A -= X;
                continue;

            case BPF_ALU | BPF_MUL | BPF_X:
                A *= X;
                continue;

            case BPF_ALU | BPF_DIV | BPF_X:
                if (X == 0)
                    return 0;
                A /= X;
                continue;

            case BPF_ALU | BPF_AND | BPF_X:
                A &= X;
                continue;

            case BPF_ALU | BPF_OR | BPF_X:
                A |= X;
                continue;

            case BPF_ALU | BPF_LSH | BPF_X:
                A <<= X;
                continue;

            case BPF_ALU | BPF_RSH | BPF_X:
                A >>= X;
                continue;

            case BPF_ALU | BPF_ADD | BPF_K:
                A += pc->k;
                continue;

            case BPF_ALU | BPF_SUB | BPF_K:
                A -= pc->k;
                continue;

            case BPF_ALU | BPF_MUL | BPF_K:
                A *= pc->k;
                continue;

            case BPF_ALU | BPF_DIV | BPF_K:
                A /= pc->k;
                continue;

            case BPF_ALU | BPF_AND | BPF_K:
                A &= pc->k;
                continue;

            case BPF_ALU | BPF_OR | BPF_K:
                A |= pc->k;
                continue;

            case BPF_ALU | BPF_LSH | BPF_K:
                A <<= pc->k;
                continue;

            case BPF_ALU | BPF_RSH | BPF_K:
                A >>= pc->k;
                continue;

            case BPF_ALU | BPF_NEG:
                A = -A;
                continue;

            case BPF_MISC | BPF_TAX:
                X = A;
                continue;

            case BPF_MISC | BPF_TXA:
                A = X;
                continue;
        }
    }
}

/*
 * Return true if the 'fcode' is a valid filter program.
 * The constraints are that each jump be forward and to a valid
 * code, that memory accesses are within valid ranges (to the
 * extent that this can be checked statically; loads of packet
 * data have to be, and are, also checked at run time), and that
 * the code terminates with either an accept or reject.
 *
 * The kernel needs to be able to verify an application's filter code.
 * Otherwise, a bogus program could easily crash the system.
 */
DAQ_SO_PUBLIC int bpf_validate(f, len)
     const struct bpf_insn *f;
     int len;
{
    u_int i, from;
    const struct bpf_insn *p;

    if (len < 1)
        return 0;
    /*
     * There's no maximum program length in userland.
     */
#if defined(KERNEL) || defined(_KERNEL)
    if (len > BPF_MAXINSNS)
        return 0;
#endif

    for (i = 0; i < len; ++i)
    {
        p = &f[i];
        switch (BPF_CLASS(p->code))
        {
                /*
                 * Check that memory operations use valid addresses.
                 */
            case BPF_LD:
            case BPF_LDX:
                switch (BPF_MODE(p->code))
                {
                    case BPF_IMM:
                        break;
                    case BPF_ABS:
                    case BPF_IND:
                    case BPF_MSH:
                        /*
                         * There's no maximum packet data size
                         * in userland.  The runtime packet length
                         * check suffices.
                         */
#if defined(KERNEL) || defined(_KERNEL)
                        /*
                         * More strict check with actual packet length
                         * is done runtime.
                         */
                        if (p->k >= bpf_maxbufsize)
                            return 0;
#endif
                        break;
                    case BPF_MEM:
                        if (p->k >= BPF_MEMWORDS)
                            return 0;
                        break;
                    case BPF_LEN:
                        break;
                    default:
                        return 0;
                }
                break;
            case BPF_ST:
            case BPF_STX:
                if (p->k >= BPF_MEMWORDS)
                    return 0;
                break;
            case BPF_ALU:
                switch (BPF_OP(p->code))
                {
                    case BPF_ADD:
                    case BPF_SUB:
                    case BPF_MUL:
                    case BPF_OR:
                    case BPF_AND:
                    case BPF_LSH:
                    case BPF_RSH:
                    case BPF_NEG:
                        break;
                    case BPF_DIV:
                        /*
                         * Check for constant division by 0.
                         */
                        if (BPF_RVAL(p->code) == BPF_K && p->k == 0)
                            return 0;
                        break;
                    default:
                        return 0;
                }
                break;
            case BPF_JMP:
                /*
                 * Check that jumps are within the code block,
                 * and that unconditional branches don't go
                 * backwards as a result of an overflow.
                 * Unconditional branches have a 32-bit offset,
                 * so they could overflow; we check to make
                 * sure they don't.  Conditional branches have
                 * an 8-bit offset, and the from address is <=
                 * BPF_MAXINSNS, and we assume that BPF_MAXINSNS
                 * is sufficiently small that adding 255 to it
                 * won't overflow.
                 *
                 * We know that len is <= BPF_MAXINSNS, and we
                 * assume that BPF_MAXINSNS is < the maximum size
                 * of a u_int, so that i + 1 doesn't overflow.
                 *
                 * For userland, we don't know that the from
                 * or len are <= BPF_MAXINSNS, but we know that
                 * from <= len, and, except on a 64-bit system,
                 * it's unlikely that len, if it truly reflects
                 * the size of the program we've been handed,
                 * will be anywhere near the maximum size of
                 * a u_int.  We also don't check for backward
                 * branches, as we currently support them in
                 * userland for the protochain operation.
                 */
                from = i + 1;
                switch (BPF_OP(p->code))
                {
                    case BPF_JA:
#if defined(KERNEL) || defined(_KERNEL)
                        if (from + p->k < from || from + p->k >= len)
#else
                        if (from + p->k >= len)
#endif
                            return 0;
                        break;
                    case BPF_JEQ:
                    case BPF_JGT:
                    case BPF_JGE:
                    case BPF_JSET:
                        if (from + p->jt >= len || from + p->jf >= len)
                            return 0;
                        break;
                    default:
                        return 0;
                }
                break;
            case BPF_RET:
                break;
            case BPF_MISC:
                break;
            default:
                return 0;
        }
    }
    return BPF_CLASS(f[len - 1].code) == BPF_RET;
}
