d0d2d47885
This change adds `ProcessVmRead` and `ProcessVmWrite` wrappers around the syscalls `process_vm_readv` and `process_vm_writev`, available since Linux 3.2. These follow the same permission model as `ptrace`, but they don't actually require being attached, which means they can be called directly from any thread in the debugger. They also use `iovec` to write entire blocks at once, rather than having to peek/poke each `uintptr`. These wrappers are used in `Thread.ReadMemory` and `WriteMemory`, still falling back to `ptrace` if that fails for any reason. Notably, `process_vm_writev` respects memory protection, so it can't modify read-only memory like `ptrace`. This frequently occurs when writing breakpoints in read-only `.text`, so to avoid a lot of wasted `EFAULT` calls, we only try `process_vm_writev` for larger writes.
80 lines
2.3 KiB
Go
80 lines
2.3 KiB
Go
package native
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import (
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"syscall"
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"unsafe"
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sys "golang.org/x/sys/unix"
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)
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// PtraceAttach executes the sys.PtraceAttach call.
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func PtraceAttach(pid int) error {
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return sys.PtraceAttach(pid)
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}
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// PtraceDetach calls ptrace(PTRACE_DETACH).
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func PtraceDetach(tid, sig int) error {
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_, _, err := sys.Syscall6(sys.SYS_PTRACE, sys.PTRACE_DETACH, uintptr(tid), 1, uintptr(sig), 0, 0)
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if err != syscall.Errno(0) {
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return err
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}
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return nil
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}
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// PtraceCont executes ptrace PTRACE_CONT
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func PtraceCont(tid, sig int) error {
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return sys.PtraceCont(tid, sig)
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}
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// PtraceSingleStep executes ptrace PTRACE_SINGLE_STEP.
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func PtraceSingleStep(tid int) error {
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return sys.PtraceSingleStep(tid)
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}
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// PtracePokeUser execute ptrace PTRACE_POKE_USER.
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func PtracePokeUser(tid int, off, addr uintptr) error {
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_, _, err := sys.Syscall6(sys.SYS_PTRACE, sys.PTRACE_POKEUSR, uintptr(tid), uintptr(off), uintptr(addr), 0, 0)
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if err != syscall.Errno(0) {
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return err
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}
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return nil
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}
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// PtracePeekUser execute ptrace PTRACE_PEEK_USER.
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func PtracePeekUser(tid int, off uintptr) (uintptr, error) {
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var val uintptr
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_, _, err := syscall.Syscall6(syscall.SYS_PTRACE, syscall.PTRACE_PEEKUSR, uintptr(tid), uintptr(off), uintptr(unsafe.Pointer(&val)), 0, 0)
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if err != syscall.Errno(0) {
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return 0, err
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}
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return val, nil
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}
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// ProcessVmRead calls process_vm_readv
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func ProcessVmRead(tid int, addr uintptr, data []byte) (int, error) {
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len_iov := uint64(len(data))
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local_iov := sys.Iovec{Base: &data[0], Len: len_iov}
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remote_iov := sys.Iovec{Base: (*byte)(unsafe.Pointer(addr)), Len: len_iov}
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p_local := uintptr(unsafe.Pointer(&local_iov))
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p_remote := uintptr(unsafe.Pointer(&remote_iov))
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n, _, err := syscall.Syscall6(sys.SYS_PROCESS_VM_READV, uintptr(tid), p_local, 1, p_remote, 1, 0)
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if err != syscall.Errno(0) {
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return 0, err
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}
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return int(n), nil
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}
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// ProcessVmWrite calls process_vm_writev
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func ProcessVmWrite(tid int, addr uintptr, data []byte) (int, error) {
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len_iov := uint64(len(data))
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local_iov := sys.Iovec{Base: &data[0], Len: len_iov}
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remote_iov := sys.Iovec{Base: (*byte)(unsafe.Pointer(addr)), Len: len_iov}
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p_local := uintptr(unsafe.Pointer(&local_iov))
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p_remote := uintptr(unsafe.Pointer(&remote_iov))
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n, _, err := syscall.Syscall6(sys.SYS_PROCESS_VM_WRITEV, uintptr(tid), p_local, 1, p_remote, 1, 0)
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if err != syscall.Errno(0) {
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return 0, err
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}
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return int(n), nil
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}
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