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stage2 macho: generate a code sig (not valid yet)

master
Jakub Konka 2020-11-20 15:48:44 +01:00
parent 9dcf7ee9c9
commit a6e93da717
3 changed files with 82 additions and 26 deletions
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8
lib/std/macho.zig
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@ -1384,10 +1384,10 @@ pub const CSTYPE_INDEX_REQUIREMENTS: u32 = 0x00000002;
/// Compat with amfi
pub const CSTYPE_INDEX_ENTITLEMENTS: u32 = 0x00000005;
pub const CS_HASHTYPE_SHA1: u32 = 1;
pub const CS_HASHTYPE_SHA256: u32 = 2;
pub const CS_HASHTYPE_SHA256_TRUNCATED: u32 = 3;
pub const CS_HASHTYPE_SHA384: u32 = 4;
pub const CS_HASHTYPE_SHA1: u8 = 1;
pub const CS_HASHTYPE_SHA256: u8 = 2;
pub const CS_HASHTYPE_SHA256_TRUNCATED: u8 = 3;
pub const CS_HASHTYPE_SHA384: u8 = 4;
pub const CS_SHA1_LEN: u32 = 20;
pub const CS_SHA256_LEN: u32 = 32;

14
src/link/MachO.zig
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@ -385,8 +385,6 @@ pub fn flushModule(self: *MachO, comp: *Compilation) !void {
try self.base.file.?.pwriteAll(mem.spanZ(LIB_SYSTEM_PATH), off);
self.libsystem_cmd_dirty = false;
}
try self.writecodeSignature();
},
.Obj => {},
.Lib => return error.TODOImplementWritingLibFiles,
@ -430,6 +428,11 @@ pub fn flushModule(self: *MachO, comp: *Compilation) !void {
assert(!self.cmd_table_dirty);
assert(!self.dylinker_cmd_dirty);
assert(!self.libsystem_cmd_dirty);
switch (self.base.options.output_mode) {
.Exe, .Lib => try self.writeCodeSignature(), // code signing always comes last
else => {},
}
}
fn linkWithLLD(self: *MachO, comp: *Compilation) !void {
@ -1486,6 +1489,9 @@ pub fn populateMissingMetadata(self: *MachO) !void {
log.debug("found code signature free space 0x{x} to 0x{x}\n", .{ off, off + file_size });
code_sig.dataoff = off;
code_sig.datasize = file_size;
const segment_size = mem.alignForwardGeneric(u64, file_size, self.page_size);
linkedit.vmsize += segment_size;
}
}
if (self.dyld_stub_binder_index == null) {
@ -1752,7 +1758,7 @@ fn writeAllUndefSymbols(self: *MachO) !void {
try self.base.file.?.pwriteAll(mem.sliceAsBytes(self.undef_symbols.items), off);
}
fn writecodeSignature(self: *MachO) !void {
fn writeCodeSignature(self: *MachO) !void {
const code_sig_cmd = &self.load_commands.items[self.code_signature_cmd_index.?].LinkeditData;
var code_sig = CodeSignature.init(self.base.allocator);
@ -1766,7 +1772,7 @@ fn writecodeSignature(self: *MachO) !void {
code_sig.write(buffer);
try self.base.file.?.pwriteAll(buffer, code_sig_cmd.dataoff);
try self.base.file.?.pwriteAll(&[_]u8{ 0 }, code_sig_cmd.dataoff + code_sig_cmd.datasize - 1);
try self.base.file.?.pwriteAll(&[_]u8{0}, code_sig_cmd.dataoff + code_sig_cmd.datasize - 1);
}
fn writeExportTrie(self: *MachO) !void {

86
src/link/MachO/CodeSignature.zig
View File

@ -7,19 +7,24 @@ const macho = std.macho;
const mem = std.mem;
const testing = std.testing;
const Allocator = mem.Allocator;
const Sha256 = std.crypto.hash.sha2.Sha256;
const MachO = @import("../MachO.zig");
const Blob = struct {
const hash_size: u8 = 32;
const page_size: u16 = 0x1000;
const CodeDirectory = struct {
inner: macho.CodeDirectory,
data: std.ArrayListUnmanaged(u8) = .{},
fn size(self: Blob) u32 {
fn size(self: CodeDirectory) u32 {
return self.inner.length;
}
fn write(self: Blob, buffer: []u8) void {
fn write(self: CodeDirectory, buffer: []u8) void {
assert(buffer.len >= self.inner.length);
mem.writeIntBig(u32, buffer[0..4], self.inner.magic);
mem.writeIntBig(u32, buffer[4..8], self.inner.length);
mem.writeIntBig(u32, buffer[8..12], self.inner.version);
@ -29,10 +34,10 @@ const Blob = struct {
mem.writeIntBig(u32, buffer[24..28], self.inner.nSpecialSlots);
mem.writeIntBig(u32, buffer[28..32], self.inner.nCodeSlots);
mem.writeIntBig(u32, buffer[32..36], self.inner.codeLimit);
mem.writeIntBig(u8, buffer[36..37], self.inner.hashSize);
mem.writeIntBig(u8, buffer[37..38], self.inner.hashType);
mem.writeIntBig(u8, buffer[38..39], self.inner.platform);
mem.writeIntBig(u8, buffer[39..40], self.inner.pageSize);
buffer[36] = self.inner.hashSize;
buffer[37] = self.inner.hashType;
buffer[38] = self.inner.platform;
buffer[39] = self.inner.pageSize;
mem.writeIntBig(u32, buffer[40..44], self.inner.spare2);
mem.writeIntBig(u32, buffer[44..48], self.inner.scatterOffset);
mem.writeIntBig(u32, buffer[48..52], self.inner.teamOffset);
@ -41,6 +46,8 @@ const Blob = struct {
mem.writeIntBig(u64, buffer[64..72], self.inner.execSegBase);
mem.writeIntBig(u64, buffer[72..80], self.inner.execSegLimit);
mem.writeIntBig(u64, buffer[80..88], self.inner.execSegFlags);
mem.copy(u8, buffer[88..], self.data.items);
}
};
@ -50,7 +57,7 @@ inner: macho.SuperBlob = .{
.length = @sizeOf(macho.SuperBlob),
.count = 0,
},
blob: ?Blob = null,
cdir: ?CodeDirectory = null,
pub fn init(alloc: *Allocator) CodeSignature {
return .{
@ -60,10 +67,14 @@ pub fn init(alloc: *Allocator) CodeSignature {
pub fn calcAdhocSignature(self: *CodeSignature, bin_file: *const MachO) !void {
const text_segment = bin_file.load_commands.items[bin_file.text_segment_cmd_index.?].Segment;
const data_segment = bin_file.load_commands.items[bin_file.data_segment_cmd_index.?].Segment;
const linkedit_segment = bin_file.load_commands.items[bin_file.linkedit_segment_cmd_index.?].Segment;
const symtab = bin_file.load_commands.items[bin_file.symtab_cmd_index.?].Symtab;
const execSegBase: u64 = text_segment.fileoff;
const execSegLimit: u64 = text_segment.filesize;
const execSegFlags: u64 = text_segment.flags;
var blob = Blob{
const execSegFlags: u64 = if (bin_file.base.options.output_mode == .Exe) macho.CS_EXECSEG_MAIN_BINARY else 0;
var cdir = CodeDirectory{
.inner = .{
.magic = macho.CSMAGIC_CODEDIRECTORY,
.length = @sizeOf(macho.CodeDirectory),
@ -74,10 +85,10 @@ pub fn calcAdhocSignature(self: *CodeSignature, bin_file: *const MachO) !void {
.nSpecialSlots = 0,
.nCodeSlots = 0,
.codeLimit = 0,
.hashSize = 0,
.hashType = 0,
.hashSize = hash_size,
.hashType = macho.CS_HASHTYPE_SHA256,
.platform = 0,
.pageSize = 0,
.pageSize = @truncate(u8, std.math.log2(page_size)),
.spare2 = 0,
.scatterOffset = 0,
.teamOffset = 0,
@ -88,9 +99,48 @@ pub fn calcAdhocSignature(self: *CodeSignature, bin_file: *const MachO) !void {
.execSegFlags = execSegFlags,
},
};
self.inner.length += @sizeOf(macho.BlobIndex) + blob.size();
const file_size = symtab.stroff + symtab.strsize;
const total_pages = mem.alignForward(file_size, page_size) / page_size;
log.debug("Total file size: {}; total number of pages: {}\n", .{ file_size, total_pages });
var hash: [hash_size]u8 = undefined;
var buffer = try bin_file.base.allocator.alloc(u8, page_size);
defer bin_file.base.allocator.free(buffer);
const macho_file = bin_file.base.file.?;
const id = bin_file.base.options.emit.?.sub_path;
try cdir.data.ensureCapacity(self.alloc, total_pages * hash_size + id.len + 1);
// 1. Save the identifier and update offsets
cdir.inner.identOffset = cdir.inner.length;
cdir.data.appendSliceAssumeCapacity(id);
cdir.data.appendAssumeCapacity(0);
// 2. Calculate hash for each page (in file) and write it to the buffer
// TODO figure out how we can cache several hashes since we won't update
// every page during incremental linking
cdir.inner.hashOffset = cdir.inner.identOffset + @intCast(u32, id.len) + 1;
var i: usize = 0;
while (i < total_pages) : (i += 1) {
const fstart = i * page_size;
const fsize = if (fstart + page_size > file_size) file_size - fstart else page_size;
const len = try macho_file.preadAll(buffer, fstart);
assert(fsize <= len);
Sha256.hash(buffer[0..fsize], &hash, .{});
log.debug("Calculated hash for page 0x{x}-0x{x}: 0x{x}\n", .{ fstart, fstart + fsize, hash[0..] });
cdir.data.appendSliceAssumeCapacity(hash[0..]);
cdir.inner.nCodeSlots += 1;
}
// 3. Update CodeDirectory length
cdir.inner.length += @intCast(u32, cdir.data.items.len);
self.inner.length += @sizeOf(macho.BlobIndex) + cdir.size();
self.inner.count = 1;
self.blob = blob;
self.cdir = cdir;
}
pub fn size(self: CodeSignature) u32 {
@ -102,12 +152,12 @@ pub fn write(self: CodeSignature, buffer: []u8) void {
self.writeHeader(buffer);
const offset: u32 = @sizeOf(macho.SuperBlob) + @sizeOf(macho.BlobIndex);
writeBlobIndex(macho.CSSLOT_CODEDIRECTORY, offset, buffer[@sizeOf(macho.SuperBlob)..]);
self.blob.?.write(buffer[offset..]);
self.cdir.?.write(buffer[offset..]);
}
pub fn deinit(self: *CodeSignature) void {
if (self.blob) |*b| {
b.data.deinit(self.alloc);
if (self.cdir) |*cdir| {
cdir.data.deinit(self.alloc);
}
}