github.com/ttpreport/gvisor-ligolo@v0.0.0-20240123134145-a858404967ba/pkg/sentry/platform/kvm/virtual_map.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 kvm
    16  
    17  import (
    18  	"bufio"
    19  	"fmt"
    20  	"io"
    21  	"os"
    22  	"regexp"
    23  	"strconv"
    24  
    25  	"github.com/ttpreport/gvisor-ligolo/pkg/hostarch"
    26  )
    27  
    28  type virtualRegion struct {
    29  	region
    30  	accessType hostarch.AccessType
    31  	shared     bool
    32  	offset     uintptr
    33  	filename   string
    34  }
    35  
    36  // mapsLine matches a single line from /proc/PID/maps.
    37  var mapsLine = regexp.MustCompile("([0-9a-f]+)-([0-9a-f]+) ([r-][w-][x-][sp]) ([0-9a-f]+) [0-9a-f]{2,3}:[0-9a-f]{2,} [0-9]+\\s+(.*)")
    38  
    39  // excludeRegion returns true if these regions should be excluded from the
    40  // physical map. Virtual regions need to be excluded if get_user_pages will
    41  // fail on those addresses, preventing KVM from satisfying EPT faults.
    42  //
    43  // This is called by the physical map functions, not applyVirtualRegions.
    44  func excludeVirtualRegion(r virtualRegion) bool {
    45  	return false
    46  }
    47  
    48  // applyVirtualRegions parses the process maps file.
    49  //
    50  // Unlike mappedRegions, these are not consistent over time.
    51  func applyVirtualRegions(fn func(vr virtualRegion)) error {
    52  	// Open /proc/self/maps.
    53  	f, err := os.Open("/proc/self/maps")
    54  	if err != nil {
    55  		return err
    56  	}
    57  	defer f.Close()
    58  
    59  	// Parse all entries.
    60  	r := bufio.NewReader(f)
    61  	for {
    62  		b, err := r.ReadBytes('\n')
    63  		if b != nil && len(b) > 0 {
    64  			m := mapsLine.FindSubmatch(b)
    65  			if m == nil {
    66  				// This should not happen: kernel bug?
    67  				return fmt.Errorf("badly formed line: %v", string(b))
    68  			}
    69  			start, err := strconv.ParseUint(string(m[1]), 16, 64)
    70  			if err != nil {
    71  				return fmt.Errorf("bad start address: %v", string(b))
    72  			}
    73  			end, err := strconv.ParseUint(string(m[2]), 16, 64)
    74  			if err != nil {
    75  				return fmt.Errorf("bad end address: %v", string(b))
    76  			}
    77  			read := m[3][0] == 'r'
    78  			write := m[3][1] == 'w'
    79  			execute := m[3][2] == 'x'
    80  			shared := m[3][3] == 's'
    81  			offset, err := strconv.ParseUint(string(m[4]), 16, 64)
    82  			if err != nil {
    83  				return fmt.Errorf("bad offset: %v", string(b))
    84  			}
    85  			fn(virtualRegion{
    86  				region: region{
    87  					virtual: uintptr(start),
    88  					length:  uintptr(end - start),
    89  				},
    90  				accessType: hostarch.AccessType{
    91  					Read:    read,
    92  					Write:   write,
    93  					Execute: execute,
    94  				},
    95  				shared:   shared,
    96  				offset:   uintptr(offset),
    97  				filename: string(m[5]),
    98  			})
    99  		}
   100  		if err != nil && err == io.EOF {
   101  			break
   102  		} else if err != nil {
   103  			return err
   104  		}
   105  	}
   106  
   107  	return nil
   108  }