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[elfabi] Add support for reading DT_NEEDED from binaries 

This patch gives elfabi the ability to read DT_NEEDED entries from ELF binaries
to populate NeededLibs in TextAPI's ELFStub.

Differential Revision: https://reviews.llvm.org/D55852

llvm-svn: 351592
This commit is contained in:
Armando Montanez 2019-01-18 20:56:03 +00:00
parent 215c4f68f6
commit 56d18121e2
3 changed files with 114 additions and 1 deletions
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45
llvm/test/tools/llvm-elfabi/binary-read-neededlibs-bad-offset.test Normal file
View File

@ -0,0 +1,45 @@
# RUN: yaml2obj %s > %t
# RUN: not llvm-elfabi --elf %t --emit-tbe=%t.tbe 2>&1 | FileCheck %s
!ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_DYN
Machine: EM_X86_64
Sections:
- Name: .dynstr
Type: SHT_STRTAB
Flags: [ SHF_ALLOC ]
Address: 0x1000
# "\0libfoo.so\0libbar.so\0somelib.so\0foo\0"
Content: "006c6962666f6f2e736f006c69626261722e736f00736f6d656c69622e736f00666f6f00"
- Name: .dynamic
Type: SHT_DYNAMIC
Flags: [ SHF_ALLOC ]
Address: 0x1024
Content: "010000000000000001000000000000000e0000000000000015000000000000000100000000000000ffff0000000000000a0000000000000024000000000000000500000000000000001000000000000000000000000000000000000000000000"
# DT_NEEDED 1 (0x01)
# DT_SONAME 21 (0x15)
# Bad DT_NEEDED entry (offset outside string table):
# DT_NEEDED 65535 (0xffff)
# DT_STRSZ 36 (0x24)
# DT_STRTAB 0x1000
# DT_NULL 0x0
Size: 96
ProgramHeaders:
- Type: PT_LOAD
Flags: [ PF_R ]
VAddr: 0x1000
PAddr: 0x1000
Align: 8
Sections:
- Section: .dynstr
- Section: .dynamic
- Type: PT_DYNAMIC
Flags: [ PF_X, PF_R ]
VAddr: 0x1024
PAddr: 0x1024
Sections:
# CHECK: DT_NEEDED string offset (0x000000000000ffff) outside of dynamic string table

47
llvm/test/tools/llvm-elfabi/binary-read-neededlibs.test Normal file
View File

@ -0,0 +1,47 @@
# RUN: yaml2obj %s -o %t
# RUN: llvm-elfabi --elf %t --emit-tbe=- | FileCheck %s
!ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_DYN
Machine: EM_X86_64
Sections:
- Name: .dynstr
Type: SHT_STRTAB
Flags: [ SHF_ALLOC ]
Address: 0x1000
# "\0libfoo.so\0libbar.so\0somelib.so\0foo\0"
Content: "006c6962666f6f2e736f006c69626261722e736f00736f6d656c69622e736f00666f6f00"
- Name: .dynamic
Type: SHT_DYNAMIC
Flags: [ SHF_ALLOC ]
Address: 0x1024
Content: "010000000000000001000000000000000e00000000000000150000000000000001000000000000000b000000000000000a0000000000000024000000000000000500000000000000001000000000000000000000000000000000000000000000"
# DT_NEEDED 1 (0x01)
# DT_SONAME 21 (0x15)
# DT_NEEDED 11 (0x0b)
# DT_STRSZ 36 (0x24)
# DT_STRTAB 0x1000
# DT_NULL 0x0
Size: 96
ProgramHeaders:
- Type: PT_LOAD
Flags: [ PF_R ]
VAddr: 0x1000
PAddr: 0x1000
Align: 8
Sections:
- Section: .dynstr
- Section: .dynamic
- Type: PT_DYNAMIC
Flags: [ PF_X, PF_R ]
VAddr: 0x1024
PAddr: 0x1024
Sections:
# CHECK: NeededLibs:
# CHECK-NEXT: - libfoo.so{{$}}
# CHECK-NEXT: - libbar.so{{$}}
# CHECK-NEXT: Symbols: {}

23
llvm/tools/llvm-elfabi/ELFObjHandler.cpp
View File

@ -31,6 +31,7 @@ struct DynamicEntries {
uint64_t StrTabAddr = 0;
uint64_t StrSize = 0;
Optional<uint64_t> SONameOffset;
std::vector<uint64_t> NeededLibNames;
};
/// This function behaves similarly to StringRef::substr(), but attempts to
@ -94,6 +95,9 @@ static Error populateDynamic(DynamicEntries &Dyn,
Dyn.StrSize = Entry.d_un.d_val;
FoundDynStrSz = true;
break;
case DT_NEEDED:
Dyn.NeededLibNames.push_back(Entry.d_un.d_val);
break;
}
}
@ -111,6 +115,14 @@ static Error populateDynamic(DynamicEntries &Dyn,
"DT_SONAME string offset (0x%016x) outside of dynamic string table",
*Dyn.SONameOffset);
}
for (uint64_t Offset : Dyn.NeededLibNames) {
if (Offset >= Dyn.StrSize) {
return createStringError(
object_error::parse_failed,
"DT_NEEDED string offset (0x%016x) outside of dynamic string table",
Offset);
}
}
return Error::success();
}
@ -164,7 +176,16 @@ buildStub(const ELFObjectFile<ELFT> &ElfObj) {
DestStub->SoName = *NameOrErr;
}
// TODO: Populate NeededLibs from .dynamic entries and linked string table.
// Populate NeededLibs from .dynamic entries and dynamic string table.
for (uint64_t NeededStrOffset : DynEnt.NeededLibNames) {
Expected<StringRef> LibNameOrErr =
terminatedSubstr(DynStr, NeededStrOffset);
if (!LibNameOrErr) {
return appendToError(LibNameOrErr.takeError(), "when reading DT_NEEDED");
}
DestStub->NeededLibs.push_back(*LibNameOrErr);
}
// TODO: Populate Symbols from .dynsym table and linked string table.
return std::move(DestStub);