Magic-Mirror/llvm-capstone
1
0
Fork 0
mirror of https://github.com/capstone-engine/llvm-capstone.git synced 2025-03-01 14:58:18 +00:00
Code Issues Actions 2 Packages Projects Releases Wiki Activity

[COFF] Add exported functions to gfids table for /guard:cf

Browse Source 
Summary:
MSVC does this, and we should to.

The .gfids table is a table of RVAs, so it's impossible for a DLL to
indicate that an imported symbol is address taken. Therefore, exports
appear to be listed as address taken by the DLL that exports them.

This fixes an issue that Firefox ran into here:
https://bugzilla.mozilla.org/show_bug.cgi?id=1485016#c12

In Firefox, the export directive came from a .def file, but we need to
do this for any kind of export.

Reviewers: dmajor, hans, amccarth, alex

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D54723

llvm-svn: 347623
This commit is contained in:
Reid Kleckner 2018-11-27 01:50:17 +00:00
parent 265cd31fbf
commit a37d672da9
2 changed files with 69 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

37
lld/COFF/Writer.cpp
View File

@ -1304,6 +1304,25 @@ static void addSymbolToRVASet(SymbolRVASet &RVASet, Defined *S) {
RVASet.insert({C, Off});
}
// Given a symbol, add it to the GFIDs table if it is a live, defined, function
// symbol in an executable section.
static void maybeAddAddressTakenFunction(SymbolRVASet &AddressTakenSyms,
Symbol *S) {
auto *D = dyn_cast_or_null<DefinedCOFF>(S);
// Ignore undefined symbols and references to non-functions (e.g. globals and
// labels).
if (!D ||
D->getCOFFSymbol().getComplexType() != COFF::IMAGE_SYM_DTYPE_FUNCTION)
return;
// Mark the symbol as address taken if it's in an executable section.
Chunk *RefChunk = D->getChunk();
OutputSection *OS = RefChunk ? RefChunk->getOutputSection() : nullptr;
if (OS && OS->Header.Characteristics & IMAGE_SCN_MEM_EXECUTE)
addSymbolToRVASet(AddressTakenSyms, D);
}
// Visit all relocations from all section contributions of this object file and
// mark the relocation target as address-taken.
static void markSymbolsWithRelocations(ObjFile *File,
@ -1322,17 +1341,7 @@ static void markSymbolsWithRelocations(ObjFile *File,
continue;
Symbol *Ref = SC->File->getSymbol(Reloc.SymbolTableIndex);
if (auto *D = dyn_cast_or_null<DefinedCOFF>(Ref)) {
if (D->getCOFFSymbol().getComplexType() != COFF::IMAGE_SYM_DTYPE_FUNCTION)
// Ignore relocations against non-functions (e.g. labels).
continue;
// Mark the symbol if it's in an executable section.
Chunk *RefChunk = D->getChunk();
OutputSection *OS = RefChunk ? RefChunk->getOutputSection() : nullptr;
if (OS && OS->Header.Characteristics & IMAGE_SCN_MEM_EXECUTE)
addSymbolToRVASet(UsedSymbols, D);
}
maybeAddAddressTakenFunction(UsedSymbols, Ref);
}
}
}
@ -1359,7 +1368,11 @@ void Writer::createGuardCFTables() {
// Mark the image entry as address-taken.
if (Config->Entry)
addSymbolToRVASet(AddressTakenSyms, cast<Defined>(Config->Entry));
maybeAddAddressTakenFunction(AddressTakenSyms, Config->Entry);
// Mark exported symbols in executable sections as address-taken.
for (Export &E : Config->Exports)
maybeAddAddressTakenFunction(AddressTakenSyms, E.Sym);
// Ensure sections referenced in the gfid table are 16-byte aligned.
for (const ChunkAndOffset &C : AddressTakenSyms)

44
lld/test/COFF/gfids-export.s Normal file
View File

@ -0,0 +1,44 @@
# REQUIRES: x86
# RUN: llvm-mc -triple x86_64-pc-win32 %s -filetype=obj -o %t.obj
# RUN: lld-link %t.obj -guard:cf -dll -out:%t.dll -noentry
# RUN: llvm-readobj -coff-load-config %t.dll | FileCheck %s --check-prefix=CHECK
# There should be a single entry in the table for the exported symbol.
#
# CHECK: GuardFidTable [
# CHECK-NEXT: 0x180001000
# CHECK-NEXT: ]
.def func_export; .scl 2; .type 32; .endef
.globl func_export
.section .text,"xr",one_only,func_export
.p2align 4
func_export:
movl $1, %eax
.globl label_export
label_export:
movl $2, %eax
ret
.data
.globl data_export
data_export:
.long 42
.section .drectve,"dr"
.ascii " /EXPORT:func_export"
.ascii " /EXPORT:label_export"
.ascii " /EXPORT:data_export"
# Load configuration directory entry (winnt.h _IMAGE_LOAD_CONFIG_DIRECTORY64).
# The linker will define the __guard_* symbols.
.section .rdata,"dr"
.globl _load_config_used
_load_config_used:
.long 256
.fill 124, 1, 0
.quad __guard_fids_table
.quad __guard_fids_count
.long __guard_flags
.fill 128, 1, 0