cisco-core.c

/* BFD back-end for CISCO crash dumps.
   Copyright (C) 1994-2019 Free Software Foundation, Inc.

   This file is part of BFD, the Binary File Descriptor library.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   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.  */

#include "sysdep.h"
#include "bfd.h"
#include "libbfd.h"
/* core_file_failing_signal returns a host signal (this probably should
   be fixed).  */
#include <signal.h>

/* for MSVC builds */
#ifndef SIGTRAP
# define SIGTRAP 5
#endif
#ifndef SIGEMT
# define SIGEMT 6
#endif
#ifndef SIGBUS
# define SIGBUS 10
#endif

int crash_info_locs[] =
{
  0x0250,	/* mips, ppc, x86, i960 */
  0x0400,	/* m68k, mips, x86, i960 */
  0x0FFC,	/* m68k, mips, ppc, x86, i960 */
  0x3000,	/* ppc */
  0x4FFC,	/* m68k */
  -1
};

#define CRASH_MAGIC	0xdead1234
#define MASK_ADDR(x)	((x) & 0x0fffffff)	/* Mask crash info address */

typedef enum
{
  CRASH_REASON_NOTCRASHED = 0,
  CRASH_REASON_EXCEPTION = 1,
  CRASH_REASON_CORRUPT = 2,
} crashreason;

typedef struct
{
  char magic[4];		/* Magic number */
  char version[4];		/* Version number */
  char reason[4];		/* Crash reason */
  char cpu_vector[4];		/* CPU vector for exceptions */
  char registers[4];		/* Pointer to saved registers */
  char rambase[4];		/* Base of RAM (not in V1 crash info) */
  char textbase[4];		/* Base of .text section (not in V3 crash info) */
  char database[4];		/* Base of .data section (not in V3 crash info) */
  char bssbase[4];		/* Base of .bss section (not in V3 crash info) */
} crashinfo_external;

struct cisco_core_struct
{
  int sig;
};

#define cisco_core_file_matches_executable_p generic_core_file_matches_executable_p
#define cisco_core_file_pid _bfd_nocore_core_file_pid

/* Examine the file for a crash info struct at the offset given by
   CRASH_INFO_LOC.  */

static const bfd_target *
cisco_core_file_validate (bfd *abfd, int crash_info_loc)
{
  char buf[4];
  unsigned int crashinfo_offset;
  crashinfo_external crashinfo;
  bfd_size_type nread;
  unsigned int magic;
  unsigned int version;
  unsigned int rambase;
  sec_ptr asect;
  struct stat statbuf;
  bfd_size_type amt;
  flagword flags;

  if (bfd_seek (abfd, (file_ptr) crash_info_loc, SEEK_SET) != 0)
    return NULL;

  nread = bfd_bread (buf, (bfd_size_type) 4, abfd);
  if (nread != 4)
    {
      if (bfd_get_error () != bfd_error_system_call)
	bfd_set_error (bfd_error_wrong_format);
      return NULL;
    }
  crashinfo_offset = MASK_ADDR (bfd_get_32 (abfd, buf));

  if (bfd_seek (abfd, (file_ptr) crashinfo_offset, SEEK_SET) != 0)
    {
      /* Most likely we failed because of a bogus (huge) offset */
      bfd_set_error (bfd_error_wrong_format);
      return NULL;
    }

  nread = bfd_bread (&crashinfo, (bfd_size_type) sizeof (crashinfo), abfd);
  if (nread != sizeof (crashinfo))
    {
      if (bfd_get_error () != bfd_error_system_call)
	bfd_set_error (bfd_error_wrong_format);
      return NULL;
    }

  if (bfd_stat (abfd, &statbuf) < 0)
    {
      bfd_set_error (bfd_error_system_call);
      return NULL;
    }

  magic = bfd_get_32 (abfd, crashinfo.magic);
  if (magic != CRASH_MAGIC)
    {
      bfd_set_error (bfd_error_wrong_format);
      return NULL;
    }

  version = bfd_get_32 (abfd, crashinfo.version);
  if (version == 0)
    {
      bfd_set_error (bfd_error_wrong_format);
      return NULL;
    }
  else if (version == 1)
    {
      /* V1 core dumps don't specify the dump base, assume 0 */
      rambase = 0;
    }
  else
    {
      rambase = bfd_get_32 (abfd, crashinfo.rambase);
    }

  /* OK, we believe you.  You're a core file.  */

  amt = sizeof (struct cisco_core_struct);
  abfd->tdata.cisco_core_data = (struct cisco_core_struct *) bfd_zmalloc (amt);
  if (abfd->tdata.cisco_core_data == NULL)
    return NULL;

  switch ((crashreason) bfd_get_32 (abfd, crashinfo.reason))
    {
    case CRASH_REASON_NOTCRASHED:
      /* Crash file probably came from write core.  */
      abfd->tdata.cisco_core_data->sig = 0;
      break;
    case CRASH_REASON_CORRUPT:
      /* The crash context area was corrupt -- proceed with caution.
	 We have no way of passing this information back to the caller.  */
      abfd->tdata.cisco_core_data->sig = 0;
      break;
    case CRASH_REASON_EXCEPTION:
      /* Crash occured due to CPU exception.  */

      /* This is 68k-specific; for MIPS we'll need to interpret
	 cpu_vector differently based on the target configuration
	 (since CISCO core files don't seem to have the processor
	 encoded in them).  */

      switch (bfd_get_32 (abfd, crashinfo.cpu_vector))
	{
	   /* bus error		  */
	case 2 : abfd->tdata.cisco_core_data->sig = SIGBUS; break;
	   /* address error	  */
	case 3 : abfd->tdata.cisco_core_data->sig = SIGBUS; break;
	   /* illegal instruction */
	case 4 : abfd->tdata.cisco_core_data->sig = SIGILL;  break;
	   /* zero divide	  */
	case 5 : abfd->tdata.cisco_core_data->sig = SIGFPE;  break;
	   /* chk instruction	  */
	case 6 : abfd->tdata.cisco_core_data->sig = SIGFPE; break;
	   /* trapv instruction	  */
	case 7 : abfd->tdata.cisco_core_data->sig = SIGFPE; break;
	   /* privilege violation */
	case 8 : abfd->tdata.cisco_core_data->sig = SIGSEGV; break;
	   /* trace trap	  */
	case 9 : abfd->tdata.cisco_core_data->sig = SIGTRAP;  break;
	   /* line 1010 emulator  */
	case 10: abfd->tdata.cisco_core_data->sig = SIGILL;  break;
	   /* line 1111 emulator  */
	case 11: abfd->tdata.cisco_core_data->sig = SIGILL;  break;

	  /* Coprocessor protocol violation.  Using a standard MMU or FPU
	     this cannot be triggered by software.  Call it a SIGBUS.  */
	case 13: abfd->tdata.cisco_core_data->sig = SIGBUS;  break;

	  /* interrupt		 */
	case 31: abfd->tdata.cisco_core_data->sig = SIGINT;  break;
	  /* breakpoint		 */
	case 33: abfd->tdata.cisco_core_data->sig = SIGTRAP;  break;

	  /* floating point err	 */
	case 48: abfd->tdata.cisco_core_data->sig = SIGFPE;  break;
	  /* floating point err	 */
	case 49: abfd->tdata.cisco_core_data->sig = SIGFPE;  break;
	  /* zero divide	 */
	case 50: abfd->tdata.cisco_core_data->sig = SIGFPE;  break;
	  /* underflow		 */
	case 51: abfd->tdata.cisco_core_data->sig = SIGFPE;  break;
	  /* operand error	 */
	case 52: abfd->tdata.cisco_core_data->sig = SIGFPE;  break;
	   /* overflow		  */
	case 53: abfd->tdata.cisco_core_data->sig = SIGFPE;  break;
	  /* NAN		 */
	case 54: abfd->tdata.cisco_core_data->sig = SIGFPE;  break;
	default:
#ifndef SIGEMT
#define SIGEMT SIGTRAP
#endif
	  /* "software generated"*/
	  abfd->tdata.cisco_core_data->sig = SIGEMT;
	}
      break;
    default:
      /* Unknown crash reason.  */
      abfd->tdata.cisco_core_data->sig = 0;
      break;
    }

  /* Create a ".data" section that maps the entire file, which is
     essentially a dump of the target system's RAM.  */

  flags = SEC_ALLOC | SEC_LOAD | SEC_HAS_CONTENTS;
  asect = bfd_make_section_anyway_with_flags (abfd, ".data", flags);
  if (asect == NULL)
    goto error_return;
  /* The size of memory is the size of the core file itself.  */
  asect->size = statbuf.st_size;
  asect->vma = rambase;
  asect->filepos = 0;

  /* Create a ".crash" section to allow access to the saved
     crash information.  */

  flags = SEC_HAS_CONTENTS;
  asect = bfd_make_section_anyway_with_flags (abfd, ".crash", flags);
  if (asect == NULL)
    goto error_return;
  asect->vma = 0;
  asect->filepos = crashinfo_offset;
  asect->size = sizeof (crashinfo);

  /* Create a ".reg" section to allow access to the saved
     registers.  */

  asect = bfd_make_section_anyway_with_flags (abfd, ".reg", flags);
  if (asect == NULL)
    goto error_return;
  asect->vma = 0;
  asect->filepos = bfd_get_32 (abfd, crashinfo.registers) - rambase;
  /* Since we don't know the exact size of the saved register info,
     choose a register section size that is either the remaining part
     of the file, or 1024, whichever is smaller.  */
  nread = statbuf.st_size - asect->filepos;
  asect->size = (nread < 1024) ? nread : 1024;

  return abfd->xvec;

  /* Get here if we have already started filling out the BFD
     and there is an error of some kind.  */

 error_return:
  bfd_release (abfd, abfd->tdata.any);
  abfd->tdata.any = NULL;
  bfd_section_list_clear (abfd);
  return NULL;
}

static const bfd_target *
cisco_core_file_p (bfd *abfd)
{
  int *crash_info_locp;
  const bfd_target *target = NULL;

  for (crash_info_locp = crash_info_locs;
       *crash_info_locp != -1  &&  target == NULL;
       crash_info_locp++)
    {
      target = cisco_core_file_validate (abfd, *crash_info_locp);
    }
  return (target);
}

static char *
cisco_core_file_failing_command (bfd *abfd ATTRIBUTE_UNUSED)
{
  return NULL;
}

static int
cisco_core_file_failing_signal (bfd *abfd ATTRIBUTE_UNUSED)
{
  return abfd->tdata.cisco_core_data->sig;
}

extern const bfd_target core_cisco_le_vec;

const bfd_target core_cisco_be_vec =
{
  "cisco-ios-core-big",
  bfd_target_unknown_flavour,
  BFD_ENDIAN_BIG,		/* target byte order */
  BFD_ENDIAN_BIG,		/* target headers byte order */
  (HAS_RELOC | EXEC_P		/* object flags */
   | HAS_LINENO | HAS_DEBUG
   | HAS_SYMS | HAS_LOCALS | WP_TEXT | D_PAGED),
  (SEC_HAS_CONTENTS | SEC_ALLOC | SEC_LOAD | SEC_RELOC), /* section flags */
  0,				/* symbol prefix */
  ' ',				/* ar_pad_char */
  16,				/* ar_max_namelen */
  0,				/* match priority.  */
  bfd_getb64, bfd_getb_signed_64, bfd_putb64,
  bfd_getb32, bfd_getb_signed_32, bfd_putb32,
  bfd_getb16, bfd_getb_signed_16, bfd_putb16, /* data */
  bfd_getb64, bfd_getb_signed_64, bfd_putb64,
  bfd_getb32, bfd_getb_signed_32, bfd_putb32,
  bfd_getb16, bfd_getb_signed_16, bfd_putb16, /* hdrs */

  {				/* bfd_check_format */
    _bfd_dummy_target,			/* unknown format */
    _bfd_dummy_target,			/* object file */
    _bfd_dummy_target,			/* archive */
    cisco_core_file_p			/* a core file */
  },
  {				/* bfd_set_format */
    _bfd_bool_bfd_false_error,
    _bfd_bool_bfd_false_error,
    _bfd_bool_bfd_false_error,
    _bfd_bool_bfd_false_error
  },
  {				/* bfd_write_contents */
    _bfd_bool_bfd_false_error,
    _bfd_bool_bfd_false_error,
    _bfd_bool_bfd_false_error,
    _bfd_bool_bfd_false_error
  },

  BFD_JUMP_TABLE_GENERIC (_bfd_generic),
  BFD_JUMP_TABLE_COPY (_bfd_generic),
  BFD_JUMP_TABLE_CORE (cisco),
  BFD_JUMP_TABLE_ARCHIVE (_bfd_noarchive),
  BFD_JUMP_TABLE_SYMBOLS (_bfd_nosymbols),
  BFD_JUMP_TABLE_RELOCS (_bfd_norelocs),
  BFD_JUMP_TABLE_WRITE (_bfd_generic),
  BFD_JUMP_TABLE_LINK (_bfd_nolink),
  BFD_JUMP_TABLE_DYNAMIC (_bfd_nodynamic),

  &core_cisco_le_vec,

  NULL				/* backend_data */
};

const bfd_target core_cisco_le_vec =
{
  "cisco-ios-core-little",
  bfd_target_unknown_flavour,
  BFD_ENDIAN_LITTLE,		/* target byte order */
  BFD_ENDIAN_LITTLE,		/* target headers byte order */
  (HAS_RELOC | EXEC_P		/* object flags */
   | HAS_LINENO | HAS_DEBUG
   | HAS_SYMS | HAS_LOCALS | WP_TEXT | D_PAGED),
  (SEC_HAS_CONTENTS | SEC_ALLOC | SEC_LOAD | SEC_RELOC), /* section flags */
  0,				/* symbol prefix */
  ' ',				/* ar_pad_char */
  16,				/* ar_max_namelen */
  0,				/* match_priority */
  bfd_getl64, bfd_getl_signed_64, bfd_putl64,
  bfd_getl32, bfd_getl_signed_32, bfd_putl32,
  bfd_getl16, bfd_getl_signed_16, bfd_putl16, /* data */
  bfd_getl64, bfd_getl_signed_64, bfd_putl64,
  bfd_getl32, bfd_getl_signed_32, bfd_putl32,
  bfd_getl16, bfd_getl_signed_16, bfd_putl16, /* hdrs */

  {				/* bfd_check_format */
    _bfd_dummy_target,			/* unknown format */
    _bfd_dummy_target,			/* object file */
    _bfd_dummy_target,			/* archive */
    cisco_core_file_p			/* a core file */
  },
  {				/* bfd_set_format */
    _bfd_bool_bfd_false_error,
    _bfd_bool_bfd_false_error,
    _bfd_bool_bfd_false_error,
    _bfd_bool_bfd_false_error
  },
  {				/* bfd_write_contents */
    _bfd_bool_bfd_false_error,
    _bfd_bool_bfd_false_error,
    _bfd_bool_bfd_false_error,
    _bfd_bool_bfd_false_error
  },

  BFD_JUMP_TABLE_GENERIC (_bfd_generic),
  BFD_JUMP_TABLE_COPY (_bfd_generic),
  BFD_JUMP_TABLE_CORE (cisco),
  BFD_JUMP_TABLE_ARCHIVE (_bfd_noarchive),
  BFD_JUMP_TABLE_SYMBOLS (_bfd_nosymbols),
  BFD_JUMP_TABLE_RELOCS (_bfd_norelocs),
  BFD_JUMP_TABLE_WRITE (_bfd_generic),
  BFD_JUMP_TABLE_LINK (_bfd_nolink),
  BFD_JUMP_TABLE_DYNAMIC (_bfd_nodynamic),

  &core_cisco_be_vec,

  NULL				/* backend_data */
};