Files
binutils-gdb/bfd/pe-x86_64.c
LIU Hao 3cad19db4e bfd,ld,dlltool: Emit delay-load import data into its own section
A delay-import symbol (of a function) is resolved when a call to it is made.
The delay loader may overwrite the `__imp_` pointer to the actual function
after it has been resolved, which requires the pointer itself be in a
writeable section.

Previously it was placed in the ordinary Import Address Table (IAT), which
is emitted into the `.idata` section, which had been changed to read-only
in db00f6c3ac, which caused segmentation
faults when functions from delay-import library were called.  This is
PR 32675.

This commit makes DLLTOOL emit delay-import IAT into `.didat`, as specified
by Microsoft. Most of the code is copied from `.idata`, except that this
section is writeable.  As a side-effect of this, PR 14339 is also fixed.

Using this DEF:

   ```
   ; ws2_32.def
   LIBRARY "WS2_32.DLL"
   EXPORTS
     WSAGetLastError
   ```

and this C program:

   ```
   // delay.c
   #define WIN32_LEAN_AND_MEAN 1
   #include <windows.h>
   #include <stdio.h>

   /////////////////////////////////////////////////////////
   // User code
   /////////////////////////////////////////////////////////

   DWORD WINAPI WSAGetLastError(void);
   extern PVOID __imp_WSAGetLastError;

   int
   main(void)
     {
       fprintf(stderr, "before delay load, __imp_WSAGetLastError = %p\n", __imp_WSAGetLastError);
       SetLastError(123);
       fprintf(stderr, "WSAGetLastError() = %d\n", WSAGetLastError());
       fprintf(stderr, "after delay load, __imp_WSAGetLastError = %p\n", __imp_WSAGetLastError);
       __imp_WSAGetLastError = (PVOID) 1234567;
       fprintf(stderr, "after plain write, __imp_WSAGetLastError = %p\n", __imp_WSAGetLastError);
     }

   /////////////////////////////////////////////////////////
   // Overridden `__delayLoadHelper2` facility
   /////////////////////////////////////////////////////////

   extern char __ImageBase[];
   PVOID WINAPI ResolveDelayLoadedAPI(PVOID ParentModuleBase, LPCVOID DelayloadDescriptor,
                                      PVOID FailureDllHook, PVOID FailureSystemHook,
                                      FARPROC* ThunkAddress, ULONG Flags);
   FARPROC WINAPI DelayLoadFailureHook(LPCSTR name, LPCSTR function);

   FARPROC WINAPI __delayLoadHelper2(LPCVOID pidd, FARPROC* ppfnIATEntry)
   {
     return ResolveDelayLoadedAPI(&__ImageBase, pidd, NULL, (PVOID) DelayLoadFailureHook,
                                  ppfnIATEntry, 0);
   }
   ```

This program used to crash:

   ```
   $ dlltool -nn -d ws2_32.def -y delay_ws2_32.a
   $ gcc -g delay.c delay_ws2_32.a -o delay.exe
   $ ./delay.exe
   before delay load, __imp_WSAGetLastError = 00007FF6937215C6
   Segmentation fault
   ```

After this commit, it loads and calls `WSAGetLastError()` properly, and
`__imp_WSAGetLastError` is writeable:

   ```
   $ dlltool -nn -d ws2_32.def -y delay_ws2_32.a
   $ gcc -g delay.c delay_ws2_32.a -o delay.exe
   $ ./delay.exe
   before delay load, __imp_WSAGetLastError = 00007FF76E2215C6
   WSAGetLastError() = 123
   after delay load, __imp_WSAGetLastError = 00007FFF191FA720
   after plain write, __imp_WSAGetLastError = 000000000012D687
   ```

Reference: https://learn.microsoft.com/en-us/windows/win32/secbp/pe-metadata#import-handling
Co-authored-by: Jeremy Drake <sourceware-bugzilla@jdrake.com>
Signed-off-by: LIU Hao <lh_mouse@126.com>
Signed-off-by: Jeremy Drake <sourceware-bugzilla@jdrake.com>
2025-06-13 07:52:29 +02:00

107 lines
3.9 KiB
C

/* BFD back-end for Intel/AMD x86_64 PECOFF files.
Copyright (C) 2006-2025 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.
Written by Kai Tietz, OneVision Software GmbH&CoKg. */
#include "sysdep.h"
#include "bfd.h"
#include "libbfd.h"
#include "libiberty.h"
#include "coff/x86_64.h"
#include "coff/internal.h"
#include "coff/pe.h"
#include "libcoff.h"
#define TARGET_SYM x86_64_pe_vec
#define TARGET_NAME "pe-x86-64"
#define TARGET_SYM_BIG x86_64_pe_big_vec
#define TARGET_NAME_BIG "pe-bigobj-x86-64"
#define COFF_WITH_PE
#define COFF_WITH_pex64
#define COFF_WITH_PE_BIGOBJ
#define PCRELOFFSET true
#if defined (USE_MINGW64_LEADING_UNDERSCORES)
#define TARGET_UNDERSCORE '_'
#else
#define TARGET_UNDERSCORE 0
#endif
#define COFF_LONG_SECTION_NAMES
#define COFF_SUPPORT_GNU_LINKONCE
#define COFF_LONG_FILENAMES
#define COFF_SECTION_ALIGNMENT_ENTRIES \
{ COFF_SECTION_NAME_EXACT_MATCH (".bss"), \
COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 4 }, \
{ COFF_SECTION_NAME_PARTIAL_MATCH (".data"), \
COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 4 }, \
{ COFF_SECTION_NAME_PARTIAL_MATCH (".rdata"), \
COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 4 }, \
{ COFF_SECTION_NAME_PARTIAL_MATCH (".text"), \
COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 4 }, \
{ COFF_SECTION_NAME_PARTIAL_MATCH (".idata"), \
COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 2 }, \
{ COFF_SECTION_NAME_PARTIAL_MATCH (".didat"), \
COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 2 }, \
{ COFF_SECTION_NAME_EXACT_MATCH (".pdata"), \
COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 2 }, \
{ COFF_SECTION_NAME_PARTIAL_MATCH (".debug"), \
COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 0 }, \
{ COFF_SECTION_NAME_PARTIAL_MATCH (".zdebug"), \
COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 0 }, \
{ COFF_SECTION_NAME_PARTIAL_MATCH (".gnu.linkonce.wi."), \
COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 0 }
/* The function pex64_bfd_print_pdata is implemented in pei-x86_64.c
source, but has be extended to also handle pe objects. */
extern bool pex64_bfd_print_pdata (bfd *, void *);
#define bfd_pe_print_pdata pex64_bfd_print_pdata
static bool
pex64_link_add_symbols (bfd *abfd, struct bfd_link_info *info)
{
if (bfd_link_pde (info)
&& bfd_get_flavour (info->output_bfd) == bfd_target_elf_flavour)
{
/* NB: When linking Windows x86-64 relocatable object files to
generate ELF executable, create an indirect reference to
__executable_start for __ImageBase to support R_AMD64_IMAGEBASE
relocation which is relative to __ImageBase. */
struct bfd_link_hash_entry *h, *hi;
hi = bfd_link_hash_lookup (info->hash, "__ImageBase", true, false,
false);
if (hi->type == bfd_link_hash_new
|| hi->type == bfd_link_hash_undefined
|| hi->type == bfd_link_hash_undefweak)
{
h = bfd_link_hash_lookup (info->hash, "__executable_start",
true, false, true);
hi->type = bfd_link_hash_indirect;
hi->u.i.link = h;
}
}
return _bfd_coff_link_add_symbols (abfd, info);
}
#define coff_bfd_link_add_symbols pex64_link_add_symbols
#include "coff-x86_64.c"