github.com/ttpreport/gvisor-ligolo@v0.0.0-20240123134145-a858404967ba/pkg/sentry/platform/systrap/subprocess_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  //go:build go1.18
    16  // +build go1.18
    17  
    18  // //go:linkname directives type-checked by checklinkname. Any other
    19  // non-linkname assumptions outside the Go 1 compatibility guarantee should
    20  // have an accompanied vet check or version guard build tag.
    21  
    22  package systrap
    23  
    24  import (
    25  	"fmt"
    26  	"unsafe"
    27  
    28  	"github.com/ttpreport/gvisor-ligolo/pkg/sentry/arch"
    29  	"github.com/ttpreport/gvisor-ligolo/pkg/sentry/memmap"
    30  	"github.com/ttpreport/gvisor-ligolo/pkg/sentry/pgalloc"
    31  	"github.com/ttpreport/gvisor-ligolo/pkg/sentry/platform/systrap/sysmsg"
    32  	"golang.org/x/sys/unix"
    33  )
    34  
    35  //go:linkname beforeFork syscall.runtime_BeforeFork
    36  func beforeFork()
    37  
    38  //go:linkname afterFork syscall.runtime_AfterFork
    39  func afterFork()
    40  
    41  //go:linkname afterForkInChild syscall.runtime_AfterForkInChild
    42  func afterForkInChild()
    43  
    44  //go:linkname cputicks runtime.cputicks
    45  func cputicks() int64
    46  
    47  // spinloop is implemented in assembly.
    48  func spinloop()
    49  
    50  // getThreadContextFromID returns a ThreadContext struct that corresponds to the
    51  // given ID.
    52  //
    53  // Precondition: cid must be a valid thread context ID that has a mapping for it
    54  // that exists in s.contexts.
    55  func (s *subprocess) getThreadContextFromID(cid uint64) *sysmsg.ThreadContext {
    56  	tcSlot := s.threadContextRegion + uintptr(cid)*sysmsg.AllocatedSizeofThreadContextStruct
    57  	return (*sysmsg.ThreadContext)(unsafe.Pointer(tcSlot))
    58  }
    59  
    60  func mmapContextQueueForSentry(memoryFile *pgalloc.MemoryFile, opts pgalloc.AllocOpts) (memmap.FileRange, *contextQueue) {
    61  	fr, err := memoryFile.Allocate(uint64(stubContextQueueRegionLen), opts)
    62  	if err != nil {
    63  		panic(fmt.Sprintf("failed to allocate a new subprocess context memory region"))
    64  	}
    65  	addr, _, errno := unix.RawSyscall6(
    66  		unix.SYS_MMAP,
    67  		0,
    68  		uintptr(fr.Length()),
    69  		unix.PROT_WRITE|unix.PROT_READ,
    70  		unix.MAP_SHARED|unix.MAP_FILE,
    71  		uintptr(memoryFile.FD()), uintptr(fr.Start))
    72  	if errno != 0 {
    73  		panic(fmt.Sprintf("mmap failed for subprocess context memory region: %v", errno))
    74  	}
    75  
    76  	return fr, (*contextQueue)(unsafe.Pointer(addr))
    77  }
    78  
    79  func saveFPState(ctx *sharedContext, ac *arch.Context64) {
    80  	fpState := ac.FloatingPointData().BytePointer()
    81  	dst := unsafeSlice(uintptr(unsafe.Pointer(fpState)), archState.FpLen())
    82  	src := ctx.shared.FPState[:]
    83  	copy(dst, src)
    84  }
    85  
    86  // restoreFPStateDecoupledContext writes FPState from c to the thread context
    87  // shared memory region if there is any need to do so.
    88  func restoreFPState(ctx *sharedContext, c *context, ac *arch.Context64) {
    89  	if !c.needRestoreFPState {
    90  		return
    91  	}
    92  	c.needRestoreFPState = false
    93  	ctx.setFPStateChanged()
    94  
    95  	fpState := ac.FloatingPointData().BytePointer()
    96  	src := unsafeSlice(uintptr(unsafe.Pointer(fpState)), archState.FpLen())
    97  	dst := ctx.shared.FPState[:]
    98  	copy(dst, src)
    99  }