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macos: add Mach task abstraction

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`std.os.darwin.MachTask` wraps `mach_port_t` and can be used to issue
kernel calls tied to the wrapped Mach kernel port/task.
This commit is contained in:
Jakub Konka 2022-03-13 13:35:37 +01:00
parent 2036af94e9
commit 633c4a2a60
6 changed files with 255 additions and 47 deletions
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1
CMakeLists.txt
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@ -460,6 +460,7 @@ set(ZIG_STAGE2_SOURCES
"${CMAKE_SOURCE_DIR}/lib/std/meta/trait.zig"
"${CMAKE_SOURCE_DIR}/lib/std/multi_array_list.zig"
"${CMAKE_SOURCE_DIR}/lib/std/os.zig"
"${CMAKE_SOURCE_DIR}/lib/std/os/darwin.zig"
"${CMAKE_SOURCE_DIR}/lib/std/os/linux.zig"
"${CMAKE_SOURCE_DIR}/lib/std/os/linux/errno/generic.zig"
"${CMAKE_SOURCE_DIR}/lib/std/os/linux/x86_64.zig"

25
lib/std/c/darwin.zig
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@ -201,9 +201,9 @@ pub const vm_object_id_t = u64;
pub const vm_region_submap_info_64 = extern struct {
// present across protection
protection: std.macho.vm_prot_t,
protection: vm_prot_t,
// max avail through vm_prot
max_protection: std.macho.vm_prot_t,
max_protection: vm_prot_t,
// behavior of map/obj on fork
inheritance: vm_inherit_t,
// offset into object/map
@ -391,6 +391,7 @@ pub const task_vm_info = extern struct {
};
pub const task_vm_info_data_t = task_vm_info;
pub const vm_prot_t = c_int;
pub const boolean_t = c_int;
pub extern "c" fn mach_vm_protect(
@ -398,7 +399,7 @@ pub extern "c" fn mach_vm_protect(
address: mach_vm_address_t,
size: mach_vm_size_t,
set_maximum: boolean_t,
new_protection: std.macho.vm_prot_t,
new_protection: vm_prot_t,
) kern_return_t;
pub extern "c" fn mach_port_deallocate(target_tport: mach_port_name_t, task: mach_port_name_t) kern_return_t;
@ -920,13 +921,19 @@ pub const STDERR_FILENO = 2;
pub const PROT = struct {
/// [MC2] no permissions
pub const NONE = 0x00;
pub const NONE: vm_prot_t = 0x00;
/// [MC2] pages can be read
pub const READ = 0x01;
pub const READ: vm_prot_t = 0x01;
/// [MC2] pages can be written
pub const WRITE = 0x02;
pub const WRITE: vm_prot_t = 0x02;
/// [MC2] pages can be executed
pub const EXEC = 0x04;
pub const EXEC: vm_prot_t = 0x04;
/// When a caller finds that they cannot obtain write permission on a
/// mapped entry, the following flag can be used. The entry will be
/// made "needs copy" effectively copying the object (using COW),
/// and write permission will be added to the maximum protections for
/// the associated entry.
pub const COPY: vm_prot_t = 0x10;
};
pub const MAP = struct {
@ -1771,6 +1778,10 @@ pub const E = enum(u16) {
_,
};
pub fn getKernError(err: kern_return_t) KernE {
return @intToEnum(KernE, err);
}
/// Kernel return values
pub const KernE = enum(u8) {
SUCCESS = 0,

41
lib/std/macho.zig
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@ -2,12 +2,16 @@ const std = @import("std");
const builtin = @import("builtin");
const assert = std.debug.assert;
const io = std.io;
const os = std.os.darwin;
const mem = std.mem;
const meta = std.meta;
const testing = std.testing;
const Allocator = mem.Allocator;
pub const cpu_type_t = os.integer_t;
pub const cpu_subtype_t = os.integer_t;
pub const mach_header = extern struct {
magic: u32,
cputype: cpu_type_t,
@ -601,10 +605,10 @@ pub const segment_command = extern struct {
filesize: u32,
/// maximum VM protection
maxprot: vm_prot_t,
maxprot: os.vm_prot_t,
/// initial VM protection
initprot: vm_prot_t,
initprot: os.vm_prot_t,
/// number of sections in segment
nsects: u32,
@ -638,10 +642,10 @@ pub const segment_command_64 = extern struct {
filesize: u64 = 0,
/// maximum VM protection
maxprot: vm_prot_t = VM_PROT_NONE,
maxprot: os.vm_prot_t = os.PROT.NONE,
/// initial VM protection
initprot: vm_prot_t = VM_PROT_NONE,
initprot: os.vm_prot_t = os.PROT.NONE,
/// number of sections in segment
nsects: u32 = 0,
@ -1438,11 +1442,6 @@ pub const S_THREAD_LOCAL_INIT_FUNCTION_POINTERS = 0x15;
/// 32-bit offsets to initializers
pub const S_INIT_FUNC_OFFSETS = 0x16;
pub const cpu_type_t = integer_t;
pub const cpu_subtype_t = integer_t;
pub const integer_t = c_int;
pub const vm_prot_t = c_int;
/// CPU type targeting 64-bit Intel-based Macs
pub const CPU_TYPE_X86_64: cpu_type_t = 0x01000007;
@ -1455,26 +1454,6 @@ pub const CPU_SUBTYPE_X86_64_ALL: cpu_subtype_t = 0x3;
/// All ARM-based Macs
pub const CPU_SUBTYPE_ARM_ALL: cpu_subtype_t = 0x0;
// Protection values defined as bits within the vm_prot_t type
/// No VM protection
pub const VM_PROT_NONE: vm_prot_t = 0x0;
/// VM read permission
pub const VM_PROT_READ: vm_prot_t = 0x1;
/// VM write permission
pub const VM_PROT_WRITE: vm_prot_t = 0x2;
/// VM execute permission
pub const VM_PROT_EXECUTE: vm_prot_t = 0x4;
/// When a caller finds that they cannot obtain write permission on a
/// mapped entry, the following flag can be used. The entry will be
/// made "needs copy" effectively copying the object (using COW),
/// and write permission will be added to the maximum protections for
/// the associated entry.
pub const VM_PROT_COPY: vm_prot_t = 0x10;
// The following are used to encode rebasing information
pub const REBASE_TYPE_POINTER: u8 = 1;
pub const REBASE_TYPE_TEXT_ABSOLUTE32: u8 = 2;
@ -2169,8 +2148,8 @@ test "read-write segment command" {
.vmaddr = 4294967296,
.vmsize = 294912,
.filesize = 294912,
.maxprot = VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE,
.initprot = VM_PROT_EXECUTE | VM_PROT_READ,
.maxprot = os.PROT.READ | os.PROT.WRITE | os.PROT.EXEC,
.initprot = os.PROT.EXEC | os.PROT.READ,
.nsects = 1,
},
};

2
lib/std/os.zig
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@ -29,7 +29,7 @@ const Allocator = std.mem.Allocator;
const Preopen = std.fs.wasi.Preopen;
const PreopenList = std.fs.wasi.PreopenList;
pub const darwin = std.c;
pub const darwin = @import("os/darwin.zig");
pub const dragonfly = std.c;
pub const freebsd = std.c;
pub const haiku = std.c;

216
lib/std/os/darwin.zig Normal file
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@ -0,0 +1,216 @@
const std = @import("std");
const log = std.log;
const mem = std.mem;
const os = @This();
pub usingnamespace @import("../c.zig");
pub const MachError = error{
/// Not enough permissions held to perform the requested kernel
/// call.
PermissionDenied,
/// Kernel returned an unhandled and unexpected error code.
/// This is a catch-all for any yet unobserved kernel response
/// to some Mach message.
Unexpected,
};
pub const MachTask = struct {
port: os.mach_port_name_t,
pub fn isValid(self: MachTask) bool {
return self.port != 0;
}
pub fn getCurrProtection(task: MachTask, address: u64, len: usize) MachError!os.vm_prot_t {
var base_addr = address;
var base_len: os.mach_vm_size_t = if (len == 1) 2 else len;
var objname: os.mach_port_t = undefined;
var info: os.vm_region_submap_info_64 = undefined;
var count: os.mach_msg_type_number_t = os.VM_REGION_SUBMAP_SHORT_INFO_COUNT_64;
switch (os.getKernError(os.mach_vm_region(
task.port,
&base_addr,
&base_len,
os.VM_REGION_BASIC_INFO_64,
@ptrCast(os.vm_region_info_t, &info),
&count,
&objname,
))) {
.SUCCESS => return info.protection,
.FAILURE => return error.PermissionDenied,
else => |err| {
log.err("mach_vm_region kernel call failed with error code: {s}", .{@tagName(err)});
return error.Unexpected;
},
}
}
pub fn setMaxProtection(task: MachTask, address: u64, len: usize, prot: os.vm_prot_t) MachError!void {
return task.setProtectionImpl(address, len, true, prot);
}
pub fn setCurrProtection(task: MachTask, address: u64, len: usize, prot: os.vm_prot_t) MachError!void {
return task.setProtectionImpl(address, len, false, prot);
}
fn setProtectionImpl(task: MachTask, address: u64, len: usize, set_max: bool, prot: os.vm_prot_t) MachError!void {
switch (os.getKernError(os.mach_vm_protect(task.port, address, len, @boolToInt(set_max), prot))) {
.SUCCESS => return,
.FAILURE => return error.PermissionDenied,
else => |err| {
log.err("mach_vm_protect kernel call failed with error code: {s}", .{@tagName(err)});
return error.Unexpected;
},
}
}
/// Will write to VM even if current protection attributes specifically prohibit
/// us from doing so, by temporarily setting protection level to a level with VM_PROT_COPY
/// variant, and resetting after a successful or unsuccessful write.
pub fn writeMemProtected(task: MachTask, address: u64, buf: []const u8, arch: std.Target.Cpu.Arch) MachError!usize {
const curr_prot = try task.getCurrProtection(address, buf.len);
try task.setCurrProtection(
address,
buf.len,
os.PROT.READ | os.PROT.WRITE | os.PROT.COPY,
);
defer {
task.setCurrProtection(address, buf.len, curr_prot) catch {};
}
return task.writeMem(address, buf, arch);
}
pub fn writeMem(task: MachTask, address: u64, buf: []const u8, arch: std.Target.Cpu.Arch) MachError!usize {
const count = buf.len;
var total_written: usize = 0;
var curr_addr = address;
const page_size = try getPageSize(task); // TODO we probably can assume value here
var out_buf = buf[0..];
while (total_written < count) {
const curr_size = maxBytesLeftInPage(page_size, curr_addr, count - total_written);
switch (os.getKernError(os.mach_vm_write(
task.port,
curr_addr,
@ptrToInt(out_buf.ptr),
@intCast(os.mach_msg_type_number_t, curr_size),
))) {
.SUCCESS => {},
.FAILURE => return error.PermissionDenied,
else => |err| {
log.err("mach_vm_write kernel call failed with error code: {s}", .{@tagName(err)});
return error.Unexpected;
},
}
switch (arch) {
.aarch64 => {
var mattr_value: os.vm_machine_attribute_val_t = os.MATTR_VAL_CACHE_FLUSH;
switch (os.getKernError(os.vm_machine_attribute(
task.port,
curr_addr,
curr_size,
os.MATTR_CACHE,
&mattr_value,
))) {
.SUCCESS => {},
.FAILURE => return error.PermissionDenied,
else => |err| {
log.err("vm_machine_attribute kernel call failed with error code: {s}", .{@tagName(err)});
return error.Unexpected;
},
}
},
.x86_64 => {},
else => unreachable,
}
out_buf = out_buf[curr_size..];
total_written += curr_size;
curr_addr += curr_size;
}
return total_written;
}
pub fn readMem(task: MachTask, address: u64, buf: []u8) MachError!usize {
const count = buf.len;
var total_read: usize = 0;
var curr_addr = address;
const page_size = try getPageSize(task); // TODO we probably can assume value here
var out_buf = buf[0..];
while (total_read < count) {
const curr_size = maxBytesLeftInPage(page_size, curr_addr, count - total_read);
var curr_bytes_read: os.mach_msg_type_number_t = 0;
var vm_memory: os.vm_offset_t = undefined;
switch (os.getKernError(os.mach_vm_read(task.port, curr_addr, curr_size, &vm_memory, &curr_bytes_read))) {
.SUCCESS => {},
.FAILURE => return error.PermissionDenied,
else => |err| {
log.err("mach_vm_read kernel call failed with error code: {s}", .{@tagName(err)});
return error.Unexpected;
},
}
@memcpy(out_buf[0..].ptr, @intToPtr([*]const u8, vm_memory), curr_bytes_read);
_ = os.vm_deallocate(os.mach_task_self(), vm_memory, curr_bytes_read);
out_buf = out_buf[curr_bytes_read..];
curr_addr += curr_bytes_read;
total_read += curr_bytes_read;
}
return total_read;
}
fn maxBytesLeftInPage(page_size: usize, address: u64, count: usize) usize {
var left = count;
if (page_size > 0) {
const page_offset = address % page_size;
const bytes_left_in_page = page_size - page_offset;
if (count > bytes_left_in_page) {
left = bytes_left_in_page;
}
}
return left;
}
fn getPageSize(task: MachTask) MachError!usize {
if (task.isValid()) {
var info_count = os.TASK_VM_INFO_COUNT;
var vm_info: os.task_vm_info_data_t = undefined;
switch (os.getKernError(os.task_info(
task.port,
os.TASK_VM_INFO,
@ptrCast(os.task_info_t, &vm_info),
&info_count,
))) {
.SUCCESS => return @intCast(usize, vm_info.page_size),
else => {},
}
}
var page_size: os.vm_size_t = undefined;
switch (os.getKernError(os._host_page_size(os.mach_host_self(), &page_size))) {
.SUCCESS => return page_size,
else => |err| {
log.err("_host_page_size kernel call failed with error code: {s}", .{@tagName(err)});
return error.Unexpected;
},
}
}
};
pub fn machTaskForPid(pid: os.pid_t) MachError!MachTask {
var port: os.mach_port_name_t = undefined;
switch (os.getKernError(os.task_for_pid(os.mach_task_self(), pid, &port))) {
.SUCCESS => {},
.FAILURE => return error.PermissionDenied,
else => |err| {
log.err("task_for_pid kernel call failed with error code: {s}", .{@tagName(err)});
return error.Unexpected;
},
}
return MachTask{ .port = port };
}

17
src/link/MachO.zig
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@ -4,6 +4,7 @@ const std = @import("std");
const build_options = @import("build_options");
const builtin = @import("builtin");
const assert = std.debug.assert;
const darwin = std.os.darwin;
const fmt = std.fmt;
const fs = std.fs;
const log = std.log.scoped(.link);
@ -4382,8 +4383,8 @@ fn populateMissingMetadata(self: *MachO) !void {
.vmaddr = pagezero_vmsize,
.vmsize = needed_size,
.filesize = needed_size,
.maxprot = macho.VM_PROT_READ | macho.VM_PROT_EXECUTE,
.initprot = macho.VM_PROT_READ | macho.VM_PROT_EXECUTE,
.maxprot = darwin.PROT.READ | darwin.PROT.EXEC,
.initprot = darwin.PROT.READ | darwin.PROT.EXEC,
},
},
});
@ -4487,8 +4488,8 @@ fn populateMissingMetadata(self: *MachO) !void {
.vmsize = needed_size,
.fileoff = fileoff,
.filesize = needed_size,
.maxprot = macho.VM_PROT_READ | macho.VM_PROT_WRITE,
.initprot = macho.VM_PROT_READ | macho.VM_PROT_WRITE,
.maxprot = darwin.PROT.READ | darwin.PROT.WRITE,
.initprot = darwin.PROT.READ | darwin.PROT.WRITE,
},
},
});
@ -4536,8 +4537,8 @@ fn populateMissingMetadata(self: *MachO) !void {
.vmsize = needed_size,
.fileoff = fileoff,
.filesize = needed_size,
.maxprot = macho.VM_PROT_READ | macho.VM_PROT_WRITE,
.initprot = macho.VM_PROT_READ | macho.VM_PROT_WRITE,
.maxprot = darwin.PROT.READ | darwin.PROT.WRITE,
.initprot = darwin.PROT.READ | darwin.PROT.WRITE,
},
},
});
@ -4645,8 +4646,8 @@ fn populateMissingMetadata(self: *MachO) !void {
.segname = makeStaticString("__LINKEDIT"),
.vmaddr = vmaddr,
.fileoff = fileoff,
.maxprot = macho.VM_PROT_READ,
.initprot = macho.VM_PROT_READ,
.maxprot = darwin.PROT.READ,
.initprot = darwin.PROT.READ,
},
},
});