github.com/ttpreport/gvisor-ligolo@v0.0.0-20240123134145-a858404967ba/pkg/sentry/platform/ptrace/ptrace_unsafe.go (about)

     1  // Copyright 2018 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package ptrace
    16  
    17  import (
    18  	"unsafe"
    19  
    20  	"github.com/ttpreport/gvisor-ligolo/pkg/abi/linux"
    21  	"github.com/ttpreport/gvisor-ligolo/pkg/hostarch"
    22  	"github.com/ttpreport/gvisor-ligolo/pkg/sentry/arch"
    23  	"github.com/ttpreport/gvisor-ligolo/pkg/sentry/arch/fpu"
    24  	"golang.org/x/sys/unix"
    25  )
    26  
    27  // getRegs gets the general purpose register set.
    28  func (t *thread) getRegs(regs *arch.Registers) error {
    29  	iovec := unix.Iovec{
    30  		Base: (*byte)(unsafe.Pointer(regs)),
    31  		Len:  uint64(unsafe.Sizeof(*regs)),
    32  	}
    33  	_, _, errno := unix.RawSyscall6(
    34  		unix.SYS_PTRACE,
    35  		unix.PTRACE_GETREGSET,
    36  		uintptr(t.tid),
    37  		linux.NT_PRSTATUS,
    38  		uintptr(unsafe.Pointer(&iovec)),
    39  		0, 0)
    40  	if errno != 0 {
    41  		return errno
    42  	}
    43  	return nil
    44  }
    45  
    46  // setRegs sets the general purpose register set.
    47  func (t *thread) setRegs(regs *arch.Registers) error {
    48  	iovec := unix.Iovec{
    49  		Base: (*byte)(unsafe.Pointer(regs)),
    50  		Len:  uint64(unsafe.Sizeof(*regs)),
    51  	}
    52  	_, _, errno := unix.RawSyscall6(
    53  		unix.SYS_PTRACE,
    54  		unix.PTRACE_SETREGSET,
    55  		uintptr(t.tid),
    56  		linux.NT_PRSTATUS,
    57  		uintptr(unsafe.Pointer(&iovec)),
    58  		0, 0)
    59  	if errno != 0 {
    60  		return errno
    61  	}
    62  	return nil
    63  }
    64  
    65  // getFPRegs gets the floating-point data via the GETREGSET ptrace unix.
    66  func (t *thread) getFPRegs(fpState *fpu.State, ac *archContext) error {
    67  	iovec := unix.Iovec{
    68  		Base: fpState.BytePointer(),
    69  		Len:  ac.floatingPointLength(),
    70  	}
    71  	_, _, errno := unix.RawSyscall6(
    72  		unix.SYS_PTRACE,
    73  		unix.PTRACE_GETREGSET,
    74  		uintptr(t.tid),
    75  		ac.floatingPointRegSet(),
    76  		uintptr(unsafe.Pointer(&iovec)),
    77  		0, 0)
    78  	if errno != 0 {
    79  		return errno
    80  	}
    81  	return nil
    82  }
    83  
    84  // setFPRegs sets the floating-point data via the SETREGSET ptrace unix.
    85  func (t *thread) setFPRegs(fpState *fpu.State, ac *archContext) error {
    86  	iovec := unix.Iovec{
    87  		Base: fpState.BytePointer(),
    88  		Len:  ac.floatingPointLength(),
    89  	}
    90  	_, _, errno := unix.RawSyscall6(
    91  		unix.SYS_PTRACE,
    92  		unix.PTRACE_SETREGSET,
    93  		uintptr(t.tid),
    94  		ac.floatingPointRegSet(),
    95  		uintptr(unsafe.Pointer(&iovec)),
    96  		0, 0)
    97  	if errno != 0 {
    98  		return errno
    99  	}
   100  	return nil
   101  }
   102  
   103  // getSignalInfo retrieves information about the signal that caused the stop.
   104  func (t *thread) getSignalInfo(si *linux.SignalInfo) error {
   105  	_, _, errno := unix.RawSyscall6(
   106  		unix.SYS_PTRACE,
   107  		unix.PTRACE_GETSIGINFO,
   108  		uintptr(t.tid),
   109  		0,
   110  		uintptr(unsafe.Pointer(si)),
   111  		0, 0)
   112  	if errno != 0 {
   113  		return errno
   114  	}
   115  	return nil
   116  }
   117  
   118  // clone creates a new thread from this one.
   119  //
   120  // The returned thread will be stopped and available for any system thread to
   121  // call attach on it.
   122  //
   123  // Precondition: the OS thread must be locked and own t.
   124  func (t *thread) clone() (*thread, error) {
   125  	r, ok := hostarch.Addr(stackPointer(&t.initRegs)).RoundUp()
   126  	if !ok {
   127  		return nil, unix.EINVAL
   128  	}
   129  	rval, err := t.syscallIgnoreInterrupt(
   130  		&t.initRegs,
   131  		unix.SYS_CLONE,
   132  		arch.SyscallArgument{Value: uintptr(
   133  			unix.CLONE_FILES |
   134  				unix.CLONE_FS |
   135  				unix.CLONE_SIGHAND |
   136  				unix.CLONE_THREAD |
   137  				unix.CLONE_PTRACE |
   138  				unix.CLONE_VM)},
   139  		// The stack pointer is just made up, but we have it be
   140  		// something sensible so the kernel doesn't think we're
   141  		// up to no good. Which we are.
   142  		arch.SyscallArgument{Value: uintptr(r)},
   143  		arch.SyscallArgument{},
   144  		arch.SyscallArgument{},
   145  		// We use these registers initially, but really they
   146  		// could be anything. We're going to stop immediately.
   147  		arch.SyscallArgument{Value: uintptr(unsafe.Pointer(&t.initRegs))})
   148  	if err != nil {
   149  		return nil, err
   150  	}
   151  
   152  	return &thread{
   153  		tgid: t.tgid,
   154  		tid:  int32(rval),
   155  		cpu:  ^uint32(0),
   156  	}, nil
   157  }
   158  
   159  // getEventMessage retrieves a message about the ptrace event that just happened.
   160  func (t *thread) getEventMessage() (uintptr, error) {
   161  	var msg uintptr
   162  	_, _, errno := unix.RawSyscall6(
   163  		unix.SYS_PTRACE,
   164  		unix.PTRACE_GETEVENTMSG,
   165  		uintptr(t.tid),
   166  		0,
   167  		uintptr(unsafe.Pointer(&msg)),
   168  		0, 0)
   169  	if errno != 0 {
   170  		return msg, errno
   171  	}
   172  	return msg, nil
   173  }