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

     1  // Copyright 2020 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 systrap
    16  
    17  import (
    18  	"fmt"
    19  	"unsafe"
    20  
    21  	"github.com/ttpreport/gvisor-ligolo/pkg/abi/linux"
    22  	"github.com/ttpreport/gvisor-ligolo/pkg/sentry/arch"
    23  	"github.com/ttpreport/gvisor-ligolo/pkg/sentry/platform/systrap/sysmsg"
    24  	"golang.org/x/sys/unix"
    25  )
    26  
    27  func (p *sysmsgThread) unmapStackFromSentry() {
    28  	_, _, errno := unix.RawSyscall(unix.SYS_MUNMAP, sysmsg.MsgToStackAddr(uintptr(unsafe.Pointer(p.msg))), sysmsg.PerThreadSharedStackSize, 0)
    29  	if errno != 0 {
    30  		panic("failed to unmap: " + errno.Error())
    31  	}
    32  }
    33  
    34  func (p *sysmsgThread) setMsg(addr uintptr) {
    35  	// add is always from the stub mapping which is mapped once and never
    36  	// moved, so it is safe to use unsafe.Pointer here.
    37  	p.msg = (*sysmsg.Msg)(unsafe.Pointer(addr))
    38  }
    39  
    40  func (p *sysmsgThread) init(sentryAddr, guestAddr uintptr) {
    41  	t := p.thread
    42  
    43  	// Set the parent death signal to SIGKILL.
    44  	_, err := t.syscallIgnoreInterrupt(&t.initRegs, unix.SYS_PRCTL,
    45  		arch.SyscallArgument{Value: linux.PR_SET_PDEATHSIG},
    46  		arch.SyscallArgument{Value: uintptr(unix.SIGKILL)},
    47  		arch.SyscallArgument{Value: 0},
    48  		arch.SyscallArgument{Value: 0},
    49  		arch.SyscallArgument{Value: 0},
    50  		arch.SyscallArgument{Value: 0},
    51  	)
    52  	if err != nil {
    53  		panic(fmt.Sprintf("prctl: %v", err))
    54  	}
    55  
    56  	// Set the sysmsg signal stack.
    57  	//
    58  	// sentryAddr is from the stub mapping which is mapped once and never
    59  	// moved, so it is safe to use unsafe.Pointer here.
    60  	alt := (*linux.SignalStack)(unsafe.Pointer(sentryAddr))
    61  	*alt = linux.SignalStack{}
    62  	alt.Addr = uint64(guestAddr)
    63  	alt.Size = uint64(sysmsg.MsgOffsetFromSharedStack)
    64  	_, err = t.syscallIgnoreInterrupt(&t.initRegs, unix.SYS_SIGALTSTACK,
    65  		arch.SyscallArgument{Value: guestAddr},
    66  		arch.SyscallArgument{Value: 0},
    67  		arch.SyscallArgument{Value: 0},
    68  		arch.SyscallArgument{Value: 0},
    69  		arch.SyscallArgument{Value: 0},
    70  		arch.SyscallArgument{Value: 0},
    71  	)
    72  	if err != nil {
    73  		panic(fmt.Sprintf("sigaltstack: %v", err))
    74  	}
    75  }
    76  
    77  // sysmsgSigactions installs signal handles for signals which can be triggered
    78  // by stubProcess and have to be handled by Sentry.
    79  //
    80  // It is called in a child process after fork(), so the race instrumentation
    81  // has to be disabled.
    82  //
    83  //go:nosplit
    84  //go:norace
    85  func sysmsgSigactions(stubSysmsgStart uintptr) unix.Errno {
    86  	act := linux.SigAction{
    87  		Handler:  uint64(stubSysmsgStart) + uint64(sysmsg.Sighandler_blob_offset____export_sighandler),
    88  		Flags:    linux.SA_ONSTACK | linux.SA_RESTORER | linux.SA_SIGINFO,
    89  		Restorer: uint64(stubSysmsgStart) + uint64(sysmsg.Sighandler_blob_offset____export_restore_rt),
    90  		Mask:     1<<(linux.SIGCHLD-1) | 1<<(linux.SIGSYS-1),
    91  	}
    92  
    93  	for _, s := range []unix.Signal{
    94  		unix.SIGSYS,
    95  		unix.SIGBUS,
    96  		unix.SIGFPE,
    97  		unix.SIGILL,
    98  		unix.SIGCHLD,
    99  		unix.SIGTRAP,
   100  		unix.SIGSEGV,
   101  	} {
   102  		_, _, errno := unix.RawSyscall6(unix.SYS_RT_SIGACTION, uintptr(s), uintptr(unsafe.Pointer(&act)), 0, 8, 0, 0)
   103  		if errno != 0 {
   104  			return errno
   105  		}
   106  	}
   107  
   108  	return 0
   109  }