[llvm] [ObjCopy] Respect requirements of LC_ENCRYPTION_INFO commands (PR #120995)
Daniel RodrÃguez Troitiño via llvm-commits
llvm-commits at lists.llvm.org
Mon Dec 23 11:16:43 PST 2024
https://github.com/drodriguez updated https://github.com/llvm/llvm-project/pull/120995
>From c4c7b0d946c2df969b4bc3b06da27ea246d5450e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Rodri=CC=81guez=20Troitin=CC=83o?=
<danielrodriguez at meta.com>
Date: Thu, 12 Sep 2024 17:33:41 -0700
Subject: [PATCH] [ObjCopy] Respect requirements of LC_ENCRYPTION_INFO commands
LLD (and other Mach-O linkers) when preparing an encryptable binary make
space to leave all the load commands in an non-encrypted page (see [1])
When using objcopy of a small encryptable binary, the code was not
respecting this fact, and the encryptable segments were not kept beyond
the first page. This was obvious for small or empty binaries.
The changes introduced here keep track if a `LC_ENCRYPTION_INFO` or
`LC_ENCRYPTION_INFO_64` has been seen, and in such case, it adds a full
page of offset in order to leave the load commands in its own page
(similar to what LLD is doing).
[1]: https://github.com/llvm/llvm-project/blob/d8e792931226b15d9d2424ecd24ccfe13adc2367/lld/MachO/SyntheticSections.cpp#L90-L93
---
llvm/lib/ObjCopy/MachO/MachOLayoutBuilder.cpp | 5 +
llvm/lib/ObjCopy/MachO/MachOObject.cpp | 4 +
llvm/lib/ObjCopy/MachO/MachOObject.h | 3 +
llvm/lib/ObjCopy/MachO/MachOReader.cpp | 4 +
.../MachO/strip-with-encryption-info.test | 217 ++++++++++++++++++
5 files changed, 233 insertions(+)
create mode 100644 llvm/test/tools/llvm-objcopy/MachO/strip-with-encryption-info.test
diff --git a/llvm/lib/ObjCopy/MachO/MachOLayoutBuilder.cpp b/llvm/lib/ObjCopy/MachO/MachOLayoutBuilder.cpp
index 93bc6631e64c86..d4eb6a9b9fc0b5 100644
--- a/llvm/lib/ObjCopy/MachO/MachOLayoutBuilder.cpp
+++ b/llvm/lib/ObjCopy/MachO/MachOLayoutBuilder.cpp
@@ -116,6 +116,11 @@ uint64_t MachOLayoutBuilder::layoutSegments() {
const bool IsObjectFile =
O.Header.FileType == MachO::HeaderFileType::MH_OBJECT;
uint64_t Offset = IsObjectFile ? (HeaderSize + O.Header.SizeOfCmds) : 0;
+ if (O.EncryptionInfoCommandIndex) {
+ // If we are emitting an encryptable binary, our load commands must have a
+ // separate (non-encrypted) page to themselves.
+ Offset = alignToPowerOf2(HeaderSize + O.Header.SizeOfCmds, PageSize);
+ }
for (LoadCommand &LC : O.LoadCommands) {
auto &MLC = LC.MachOLoadCommand;
StringRef Segname;
diff --git a/llvm/lib/ObjCopy/MachO/MachOObject.cpp b/llvm/lib/ObjCopy/MachO/MachOObject.cpp
index d593d6788e112f..fe4b1cf4b12ae5 100644
--- a/llvm/lib/ObjCopy/MachO/MachOObject.cpp
+++ b/llvm/lib/ObjCopy/MachO/MachOObject.cpp
@@ -85,6 +85,10 @@ void Object::updateLoadCommandIndexes() {
case MachO::LC_DYLD_EXPORTS_TRIE:
ExportsTrieCommandIndex = Index;
break;
+ case MachO::LC_ENCRYPTION_INFO:
+ case MachO::LC_ENCRYPTION_INFO_64:
+ EncryptionInfoCommandIndex = Index;
+ break;
}
}
}
diff --git a/llvm/lib/ObjCopy/MachO/MachOObject.h b/llvm/lib/ObjCopy/MachO/MachOObject.h
index b3303fd291c82c..b616677b83dcbc 100644
--- a/llvm/lib/ObjCopy/MachO/MachOObject.h
+++ b/llvm/lib/ObjCopy/MachO/MachOObject.h
@@ -340,6 +340,9 @@ struct Object {
/// The index of the LC_SEGMENT or LC_SEGMENT_64 load command
/// corresponding to the __TEXT segment.
std::optional<size_t> TextSegmentCommandIndex;
+ /// The index of the LC_ENCRYPTION_INFO or LC_ENCRYPTION_INFO_64 load command
+ /// if present.
+ std::optional<size_t> EncryptionInfoCommandIndex;
BumpPtrAllocator Alloc;
StringSaver NewSectionsContents;
diff --git a/llvm/lib/ObjCopy/MachO/MachOReader.cpp b/llvm/lib/ObjCopy/MachO/MachOReader.cpp
index 2b344f36d8e78b..ef0e0262f93958 100644
--- a/llvm/lib/ObjCopy/MachO/MachOReader.cpp
+++ b/llvm/lib/ObjCopy/MachO/MachOReader.cpp
@@ -184,6 +184,10 @@ Error MachOReader::readLoadCommands(Object &O) const {
case MachO::LC_DYLD_CHAINED_FIXUPS:
O.ChainedFixupsCommandIndex = O.LoadCommands.size();
break;
+ case MachO::LC_ENCRYPTION_INFO:
+ case MachO::LC_ENCRYPTION_INFO_64:
+ O.EncryptionInfoCommandIndex = O.LoadCommands.size();
+ break;
}
#define HANDLE_LOAD_COMMAND(LCName, LCValue, LCStruct) \
case MachO::LCName: \
diff --git a/llvm/test/tools/llvm-objcopy/MachO/strip-with-encryption-info.test b/llvm/test/tools/llvm-objcopy/MachO/strip-with-encryption-info.test
new file mode 100644
index 00000000000000..19b06b1ec02c81
--- /dev/null
+++ b/llvm/test/tools/llvm-objcopy/MachO/strip-with-encryption-info.test
@@ -0,0 +1,217 @@
+# RUN: rm -rf %t && mkdir %t
+# RUN: yaml2obj %s -o %t/original
+# RUN: llvm-strip --strip-all %t/original -o %t/stripped
+# RUN: llvm-readobj --macho-segment %t/stripped | FileCheck %s
+
+# CHECK-LABEL: Name: __PAGEZERO
+# CHECK: fileoff: 16384
+
+# CHECK-LABEL: Name: __TEXT
+# CHECK: fileoff: 16384
+
+# The YAML below is the following code
+# int main(int argc, char **argv) { return 0; }
+# Compiled on macOS against the macOS SDK and passing `-Wl,-encryptable`
+# Contents are removed, since they are not important for the test. We need a
+# small text segment (smaller than a page).
+--- !mach-o
+FileHeader:
+ magic: 0xFEEDFACF
+ cputype: 0x100000C
+ cpusubtype: 0x0
+ filetype: 0x2
+ ncmds: 15
+ sizeofcmds: 696
+ flags: 0x200085
+ reserved: 0x0
+LoadCommands:
+ - cmd: LC_SEGMENT_64
+ cmdsize: 72
+ segname: __PAGEZERO
+ vmaddr: 0
+ vmsize: 4294967296
+ fileoff: 0
+ filesize: 0
+ maxprot: 0
+ initprot: 0
+ nsects: 0
+ flags: 0
+ - cmd: LC_SEGMENT_64
+ cmdsize: 232
+ segname: __TEXT
+ vmaddr: 4294967296
+ vmsize: 32768
+ fileoff: 0
+ filesize: 32768
+ maxprot: 5
+ initprot: 5
+ nsects: 2
+ flags: 0
+ Sections:
+ - sectname: __text
+ segname: __TEXT
+ addr: 0x100004000
+ size: 32
+ offset: 0x4000
+ align: 2
+ reloff: 0x0
+ nreloc: 0
+ flags: 0x80000400
+ reserved1: 0x0
+ reserved2: 0x0
+ reserved3: 0x0
+ - sectname: __unwind_info
+ segname: __TEXT
+ addr: 0x100004020
+ size: 4152
+ offset: 0x4020
+ align: 2
+ reloff: 0x0
+ nreloc: 0
+ flags: 0x0
+ reserved1: 0x0
+ reserved2: 0x0
+ reserved3: 0x0
+ - cmd: LC_SEGMENT_64
+ cmdsize: 72
+ segname: __LINKEDIT
+ vmaddr: 4295000064
+ vmsize: 592
+ fileoff: 32768
+ filesize: 592
+ maxprot: 1
+ initprot: 1
+ nsects: 0
+ flags: 0
+ - cmd: LC_DYLD_CHAINED_FIXUPS
+ cmdsize: 16
+ dataoff: 32768
+ datasize: 48
+ - cmd: LC_DYLD_EXPORTS_TRIE
+ cmdsize: 16
+ dataoff: 32816
+ datasize: 48
+ - cmd: LC_SYMTAB
+ cmdsize: 24
+ symoff: 32872
+ nsyms: 2
+ stroff: 32904
+ strsize: 32
+ - cmd: LC_DYSYMTAB
+ cmdsize: 80
+ ilocalsym: 0
+ nlocalsym: 0
+ iextdefsym: 0
+ nextdefsym: 2
+ iundefsym: 2
+ nundefsym: 0
+ tocoff: 0
+ ntoc: 0
+ modtaboff: 0
+ nmodtab: 0
+ extrefsymoff: 0
+ nextrefsyms: 0
+ indirectsymoff: 0
+ nindirectsyms: 0
+ extreloff: 0
+ nextrel: 0
+ locreloff: 0
+ nlocrel: 0
+ - cmd: LC_ENCRYPTION_INFO_64
+ cmdsize: 24
+ cryptoff: 16384
+ cryptsize: 16384
+ cryptid: 0
+ pad: 0
+ - cmd: LC_LOAD_DYLINKER
+ cmdsize: 32
+ name: 12
+ Content: '/usr/lib/dyld'
+ ZeroPadBytes: 7
+ - cmd: LC_UUID
+ cmdsize: 24
+ uuid: 4C4C4447-5555-3144-A18A-01E9EB7E7D92
+ - cmd: LC_BUILD_VERSION
+ cmdsize: 32
+ platform: 1
+ minos: 983040
+ sdk: 983552
+ ntools: 1
+ Tools:
+ - tool: 4
+ version: 1310720
+ - cmd: LC_MAIN
+ cmdsize: 24
+ entryoff: 16384
+ stacksize: 0
+ - cmd: LC_FUNCTION_STARTS
+ cmdsize: 16
+ dataoff: 32864
+ datasize: 8
+ - cmd: LC_DATA_IN_CODE
+ cmdsize: 16
+ dataoff: 32872
+ datasize: 0
+ - cmd: LC_CODE_SIGNATURE
+ cmdsize: 16
+ dataoff: 32944
+ datasize: 416
+LinkEditData:
+ ExportTrie:
+ TerminalSize: 0
+ NodeOffset: 0
+ Name: ''
+ Flags: 0x0
+ Address: 0x0
+ Other: 0x0
+ ImportName: ''
+ Children:
+ - TerminalSize: 0
+ NodeOffset: 5
+ Name: _
+ Flags: 0x0
+ Address: 0x0
+ Other: 0x0
+ ImportName: ''
+ Children:
+ - TerminalSize: 4
+ NodeOffset: 33
+ Name: main
+ Flags: 0x0
+ Address: 0x4000
+ Other: 0x0
+ ImportName: ''
+ - TerminalSize: 2
+ NodeOffset: 39
+ Name: _mh_execute_header
+ Flags: 0x0
+ Address: 0x0
+ Other: 0x0
+ ImportName: ''
+ NameList:
+ - n_strx: 2
+ n_type: 0xF
+ n_sect: 1
+ n_desc: 0
+ n_value: 4294983680
+ - n_strx: 8
+ n_type: 0xF
+ n_sect: 1
+ n_desc: 16
+ n_value: 4294967296
+ StringTable:
+ - ' '
+ - _main
+ - __mh_execute_header
+ - ''
+ - ''
+ - ''
+ - ''
+ FunctionStarts: [ 0x4000 ]
+ ChainedFixups: [ 0x0, 0x0, 0x0, 0x0, 0x20, 0x0, 0x0, 0x0, 0x30, 0x0,
+ 0x0, 0x0, 0x30, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+ 0x1, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+ 0x0, 0x0, 0x3, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+ 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0 ]
+...
+
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