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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>
107 lines
3.9 KiB
C
107 lines
3.9 KiB
C
/* BFD back-end for Intel/AMD x86_64 PECOFF files.
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Copyright (C) 2006-2025 Free Software Foundation, Inc.
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This file is part of BFD, the Binary File Descriptor library.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
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MA 02110-1301, USA.
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Written by Kai Tietz, OneVision Software GmbH&CoKg. */
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#include "sysdep.h"
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#include "bfd.h"
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#include "libbfd.h"
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#include "libiberty.h"
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#include "coff/x86_64.h"
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#include "coff/internal.h"
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#include "coff/pe.h"
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#include "libcoff.h"
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#define TARGET_SYM x86_64_pe_vec
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#define TARGET_NAME "pe-x86-64"
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#define TARGET_SYM_BIG x86_64_pe_big_vec
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#define TARGET_NAME_BIG "pe-bigobj-x86-64"
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#define COFF_WITH_PE
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#define COFF_WITH_pex64
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#define COFF_WITH_PE_BIGOBJ
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#define PCRELOFFSET true
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#if defined (USE_MINGW64_LEADING_UNDERSCORES)
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#define TARGET_UNDERSCORE '_'
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#else
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#define TARGET_UNDERSCORE 0
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#endif
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#define COFF_LONG_SECTION_NAMES
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#define COFF_SUPPORT_GNU_LINKONCE
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#define COFF_LONG_FILENAMES
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#define COFF_SECTION_ALIGNMENT_ENTRIES \
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{ COFF_SECTION_NAME_EXACT_MATCH (".bss"), \
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COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 4 }, \
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{ COFF_SECTION_NAME_PARTIAL_MATCH (".data"), \
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COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 4 }, \
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{ COFF_SECTION_NAME_PARTIAL_MATCH (".rdata"), \
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COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 4 }, \
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{ COFF_SECTION_NAME_PARTIAL_MATCH (".text"), \
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COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 4 }, \
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{ COFF_SECTION_NAME_PARTIAL_MATCH (".idata"), \
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COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 2 }, \
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{ COFF_SECTION_NAME_PARTIAL_MATCH (".didat"), \
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COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 2 }, \
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{ COFF_SECTION_NAME_EXACT_MATCH (".pdata"), \
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COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 2 }, \
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{ COFF_SECTION_NAME_PARTIAL_MATCH (".debug"), \
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COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 0 }, \
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{ COFF_SECTION_NAME_PARTIAL_MATCH (".zdebug"), \
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COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 0 }, \
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{ COFF_SECTION_NAME_PARTIAL_MATCH (".gnu.linkonce.wi."), \
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COFF_ALIGNMENT_FIELD_EMPTY, COFF_ALIGNMENT_FIELD_EMPTY, 0 }
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/* The function pex64_bfd_print_pdata is implemented in pei-x86_64.c
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source, but has be extended to also handle pe objects. */
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extern bool pex64_bfd_print_pdata (bfd *, void *);
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#define bfd_pe_print_pdata pex64_bfd_print_pdata
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static bool
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pex64_link_add_symbols (bfd *abfd, struct bfd_link_info *info)
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{
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if (bfd_link_pde (info)
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&& bfd_get_flavour (info->output_bfd) == bfd_target_elf_flavour)
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{
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/* NB: When linking Windows x86-64 relocatable object files to
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generate ELF executable, create an indirect reference to
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__executable_start for __ImageBase to support R_AMD64_IMAGEBASE
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relocation which is relative to __ImageBase. */
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struct bfd_link_hash_entry *h, *hi;
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hi = bfd_link_hash_lookup (info->hash, "__ImageBase", true, false,
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false);
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if (hi->type == bfd_link_hash_new
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|| hi->type == bfd_link_hash_undefined
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|| hi->type == bfd_link_hash_undefweak)
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{
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h = bfd_link_hash_lookup (info->hash, "__executable_start",
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true, false, true);
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hi->type = bfd_link_hash_indirect;
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hi->u.i.link = h;
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}
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}
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return _bfd_coff_link_add_symbols (abfd, info);
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}
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#define coff_bfd_link_add_symbols pex64_link_add_symbols
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#include "coff-x86_64.c"
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