/*
 *  Copyright (C) 2009 Sourcefire, Inc.
 *
 *  Authors: Tomasz Kojm <tkojm@clamav.net>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as
 *  published by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 *  MA 02110-1301, USA.
 */

/* TODO:
 *  - handle LC_THREAD
 *  - integrate with the matcher
 */

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#include "clamav.h"
#include "cltypes.h"
#include "others.h"
#include "macho.h"
#include "execs.h"

#define EC32(v, conv)	(conv ? cbswap32(v) : v)
#define EC64(v, conv)	(conv ? cbswap64(v) : v)

struct macho_hdr
{
    uint32_t magic;
    uint32_t cpu_type;
    uint32_t cpu_subtype;
    uint32_t filetype;
    uint32_t ncmds;
    uint32_t sizeofcmds;
    uint32_t flags;
};

struct macho_load_cmd
{
    uint32_t cmd;
    uint32_t cmdsize;
};

struct macho_segment_cmd
{
    char segname[16];
    uint32_t vmaddr;
    uint32_t vmsize;
    uint32_t fileoff;
    uint32_t filesize;
    uint32_t maxprot;
    uint32_t initprot;
    uint32_t nsects;
    uint32_t flags;
};

struct macho_segment_cmd64
{
    char segname[16];
    uint64_t vmaddr;
    uint64_t vmsize;
    uint64_t fileoff;
    uint64_t filesize;
    uint32_t maxprot;
    uint32_t initprot;
    uint32_t nsects;
    uint32_t flags;
};

struct macho_section
{
    char sectname[16];
    char segname[16];
    uint32_t addr;
    uint32_t size;
    uint32_t offset;
    uint32_t align;
    uint32_t reloff;
    uint32_t nreloc;
    uint32_t flags;
    uint32_t res1;
    uint32_t res2;
};

struct macho_section64
{
    char sectname[16];
    char segname[16];
    uint64_t addr;
    uint64_t size;
    uint32_t offset;
    uint32_t align;
    uint32_t reloff;
    uint32_t nreloc;
    uint32_t flags;
    uint32_t res1;
    uint32_t res2;
};

int cli_scanmacho(int fd, cli_ctx *ctx)
{
	struct macho_hdr hdr;
	struct macho_load_cmd load_cmd;
	struct macho_segment_cmd segment_cmd;
	struct macho_segment_cmd64 segment_cmd64;
	struct macho_section section;
	struct macho_section64 section64;
	unsigned int i, j, sect = 0, conv, m64, nsects, vaddr, vsize, offset;
	char name[16];

    if(read(fd, &hdr, sizeof(hdr)) != sizeof(hdr)) {
	cli_dbgmsg("cli_scanmacho: Can't read header\n");
	return CL_EFORMAT;
    }

    if(hdr.magic == 0xfeedface) {
	conv = 0;
	m64 = 0;
    } else if(hdr.magic == 0xcefaedfe) {
	conv = 1;
	m64 = 0;
    } else if(hdr.magic == 0xfeedfacf) {
	conv = 0;
	m64 = 1;
    } else if(hdr.magic == 0xcffaedfe) {
	conv = 1;
	m64 = 1;
    } else {
	cli_dbgmsg("cli_scanmacho: Incorrect magic\n");
	return CL_EFORMAT;
    }

    switch(EC32(hdr.cpu_type, conv)) {
	case 7:
	    cli_dbgmsg("MACHO: CPU Type: Intel 32-bit\n");
	    break;
	case 7 | 0x1000000:
	    cli_dbgmsg("MACHO: CPU Type: Intel 64-bit\n");
	    break;
	case 12:
	    cli_dbgmsg("MACHO: CPU Type: ARM\n");
	    break;
	case 14:
	    cli_dbgmsg("MACHO: CPU Type: SPARC\n");
	    break;
	case 18:
	    cli_dbgmsg("MACHO: CPU Type: POWERPC 32-bit\n");
	    break;
	case 18 | 0x1000000:
	    cli_dbgmsg("MACHO: CPU Type: POWERPC 64-bit\n");
	    break;
	default:
	    cli_dbgmsg("MACHO: CPU Type: ** UNKNOWN ** (%u)\n", EC32(hdr.cpu_type, conv));
	    break;
    }

    switch(EC32(hdr.filetype, conv)) {
	case 0x1: /* MH_OBJECT */
	    cli_dbgmsg("MACHO: Filetype: Relocatable object file\n");
	    break;
	case 0x2: /* MH_EXECUTE */
	    cli_dbgmsg("MACHO: Filetype: Executable\n");
	    break;
	case 0x3: /* MH_FVMLIB */
	    cli_dbgmsg("MACHO: Filetype: Fixed VM shared library file\n");
	    break;
	case 0x4: /* MH_CORE */
	    cli_dbgmsg("MACHO: Filetype: Core file\n");
	    break;
	case 0x5: /* MH_PRELOAD */
	    cli_dbgmsg("MACHO: Filetype: Preloaded executable file\n");
	    break;
	case 0x6: /* MH_DYLIB */
	    cli_dbgmsg("MACHO: Filetype: Dynamically bound shared library\n");
	    break;
	case 0x7: /* MH_DYLINKER */
	    cli_dbgmsg("MACHO: Filetype: Dynamic link editor\n");
	    break;
	case 0x8: /* MH_BUNDLE */
	    cli_dbgmsg("MACHO: Filetype: Dynamically bound bundle file\n");
	    break;
	case 0x9: /* MH_DYLIB_STUB */
	    cli_dbgmsg("MACHO: Filetype: Shared library stub for static\n");
	    break;
	default:
	    cli_dbgmsg("MACHO: Filetype: ** UNKNOWN ** (0x%x)\n", EC32(hdr.filetype, conv));
    }

    cli_dbgmsg("MACHO: Number of load commands: %u\n", EC32(hdr.ncmds, conv));
    cli_dbgmsg("MACHO: Size of load commands: %u\n", EC32(hdr.sizeofcmds, conv));

    if((m64 && EC32(load_cmd.cmdsize, conv) % 8) || (!m64 && EC32(load_cmd.cmdsize, conv) % 4)) {
	cli_dbgmsg("cli_scanmacho: Invalid command size (%u)\n", EC32(load_cmd.cmdsize, conv));
        if(DETECT_BROKEN) {
	    if(ctx->virname)
		*ctx->virname = "Broken.Executable";
	    return cli_checkfp(fd, ctx) ? CL_CLEAN : CL_VIRUS;
        }
	return CL_EFORMAT;
    }

    if(m64)
	lseek(fd, 4, SEEK_CUR);

    for(i = 0; i < EC32(hdr.ncmds, conv); i++) {
	if(read(fd, &load_cmd, sizeof(load_cmd)) != sizeof(load_cmd)) {
	    cli_dbgmsg("cli_scanmacho: Can't read load command\n");
	    if(DETECT_BROKEN) {
		if(ctx->virname)
		    *ctx->virname = "Broken.Executable";
		return cli_checkfp(fd, ctx) ? CL_CLEAN : CL_VIRUS;
	    }
	    return CL_EFORMAT;
	}

	if((m64 && EC32(load_cmd.cmd, conv) == 0x19) || (!m64 && EC32(load_cmd.cmd, conv) == 0x01)) { /* LC_SEGMENT */
	    if(m64) {
		if(read(fd, &segment_cmd64, sizeof(segment_cmd64)) != sizeof(segment_cmd64)) {
		    cli_dbgmsg("cli_scanmacho: Can't read segment command\n");
		    if(DETECT_BROKEN) {
			if(ctx->virname)
			    *ctx->virname = "Broken.Executable";
			return cli_checkfp(fd, ctx) ? CL_CLEAN : CL_VIRUS;
		    }
		    return CL_EFORMAT;
		}
		nsects = EC32(segment_cmd64.nsects, conv);
		strncpy(name, segment_cmd64.segname, 16);
	    } else {
		if(read(fd, &segment_cmd, sizeof(segment_cmd)) != sizeof(segment_cmd)) {
		    cli_dbgmsg("cli_scanmacho: Can't read segment command\n");
		    if(DETECT_BROKEN) {
			if(ctx->virname)
			    *ctx->virname = "Broken.Executable";
			return cli_checkfp(fd, ctx) ? CL_CLEAN : CL_VIRUS;
		    }
		    return CL_EFORMAT;
		}
		nsects = EC32(segment_cmd.nsects, conv);
		strncpy(name, segment_cmd.segname, 16);
	    }
	    name[15] = 0;
	    cli_dbgmsg("MACHO: Segment name: %s\n", name);
	    cli_dbgmsg("MACHO: Number of sections: %u\n", nsects);
	    for(j = 0; j < nsects; j++) {
		if(m64) {
		    if(read(fd, &section64, sizeof(section64)) != sizeof(section64)) {
			cli_dbgmsg("cli_scanmacho: Can't read section\n");
			if(DETECT_BROKEN) {
			    if(ctx->virname)
				*ctx->virname = "Broken.Executable";
			    return cli_checkfp(fd, ctx) ? CL_CLEAN : CL_VIRUS;
			}
			return CL_EFORMAT;
		    }
		    vaddr = EC64(section64.addr, conv);
		    vsize = EC64(section64.size, conv);
		    offset = EC32(section64.offset, conv);
		    strncpy(name, section64.sectname, 16);
		} else {
		    if(read(fd, &section, sizeof(section)) != sizeof(section)) {
			cli_dbgmsg("cli_scanmacho: Can't read section\n");
			if(DETECT_BROKEN) {
			    if(ctx->virname)
				*ctx->virname = "Broken.Executable";
			    return cli_checkfp(fd, ctx) ? CL_CLEAN : CL_VIRUS;
			}
			return CL_EFORMAT;
		    }
		    vaddr = EC32(section.addr, conv);
		    vsize = EC32(section.size, conv);
		    offset = EC32(section.offset, conv);
		    strncpy(name, section.sectname, 16);
		}
		name[15] = 0;
		cli_dbgmsg("MACHO: --- Section %u ---\n", sect);
		cli_dbgmsg("MACHO: Name: %s\n", name);
		cli_dbgmsg("MACHO: Virtual address: 0x%x\n", vaddr);
		cli_dbgmsg("MACHO: Virtual size: %u\n", vsize);
		if(offset)
		    cli_dbgmsg("MACHO: File offset: %u\n", offset);
		sect++;
	    }
	    cli_dbgmsg("MACHO: ------------------\n");
	} else {
	    if(EC32(load_cmd.cmdsize, conv) > sizeof(load_cmd))
		lseek(fd, EC32(load_cmd.cmdsize, conv) - sizeof(load_cmd), SEEK_CUR);
	}
    }

    return CL_SUCCESS;
}

int cli_machoheader(int fd, struct cli_exe_info *elfinfo)
{
	struct macho_hdr hdr;
	struct macho_load_cmd load_cmd;
	struct macho_segment_cmd segment_cmd;
	struct macho_segment_cmd64 segment_cmd64;
	struct macho_section section;
	struct macho_section64 section64;
	unsigned int i, j, sect = 0, conv, m64, nsects, vaddr, vsize, offset;

    cli_dbgmsg("in cli_machoheader()\n");

    if(read(fd, &hdr, sizeof(hdr)) != sizeof(hdr)) {
	cli_dbgmsg("cli_scanmacho: Can't read header\n");
	return -1;
    }

    if(hdr.magic == 0xfeedface) {
	conv = 0;
	m64 = 0;
    } else if(hdr.magic == 0xcefaedfe) {
	conv = 1;
	m64 = 0;
    } else if(hdr.magic == 0xfeedfacf) {
	conv = 0;
	m64 = 1;
    } else if(hdr.magic == 0xcffaedfe) {
	conv = 1;
	m64 = 1;
    } else {
	cli_dbgmsg("cli_scanmacho: Incorrect magic\n");
	return CL_EFORMAT;
    }

    if((m64 && EC32(load_cmd.cmdsize, conv) % 8) || (!m64 && EC32(load_cmd.cmdsize, conv) % 4)) {
	cli_dbgmsg("cli_scanmacho: Invalid command size (%u)\n", EC32(load_cmd.cmdsize, conv));
	return -1;
    }

    if(m64)
	lseek(fd, 4, SEEK_CUR);

    for(i = 0; i < EC32(hdr.ncmds, conv); i++) {
	if(read(fd, &load_cmd, sizeof(load_cmd)) != sizeof(load_cmd)) {
	    cli_dbgmsg("cli_scanmacho: Can't read load command\n");
	    return -1;
	}

	if((m64 && EC32(load_cmd.cmd, conv) == 0x19) || (!m64 && EC32(load_cmd.cmd, conv) == 0x01)) { /* LC_SEGMENT */
	    if(m64) {
		if(read(fd, &segment_cmd64, sizeof(segment_cmd64)) != sizeof(segment_cmd64)) {
		    cli_dbgmsg("cli_scanmacho: Can't read segment command\n");
		    return -1;
		}
		nsects = EC32(segment_cmd64.nsects, conv);
	    } else {
		if(read(fd, &segment_cmd, sizeof(segment_cmd)) != sizeof(segment_cmd)) {
		    cli_dbgmsg("cli_scanmacho: Can't read segment command\n");
		    return -1;
		}
		nsects = EC32(segment_cmd.nsects, conv);
	    }
	    for(j = 0; j < nsects; j++) {
		if(m64) {
		    if(read(fd, &section64, sizeof(section64)) != sizeof(section64)) {
			cli_dbgmsg("cli_scanmacho: Can't read section\n");
			return -1;
		    }
		    vaddr = EC64(section64.addr, conv);
		    vsize = EC64(section64.size, conv);
		    offset = EC32(section64.offset, conv);
		} else {
		    if(read(fd, &section, sizeof(section)) != sizeof(section)) {
			cli_dbgmsg("cli_scanmacho: Can't read section\n");
			return -1;
		    }
		    vaddr = EC32(section.addr, conv);
		    vsize = EC32(section.size, conv);
		    offset = EC32(section.offset, conv);
		}
		sect++;
	    }
	} else {
	    if(EC32(load_cmd.cmdsize, conv) > sizeof(load_cmd))
		lseek(fd, EC32(load_cmd.cmdsize, conv) - sizeof(load_cmd), SEEK_CUR);
	}
    }

    return 0;
}