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// Copyright 2024 syzkaller project authors. All rights reserved.
// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
package vminfo
import (
"bufio"
"bytes"
"fmt"
"io"
"path"
"regexp"
"sort"
"strconv"
"strings"
"github.com/google/syzkaller/sys/targets"
)
type linux struct {
vmType string
}
func (linux) RequiredFiles() []string {
return []string{
"/proc/cpuinfo",
"/proc/modules",
"/proc/kallsyms",
"/sys/module/*/sections/.text",
"/sys/module/kvm*/parameters/*",
}
}
func (linux) CheckFiles() []string {
return []string{
"/proc/version",
"/proc/filesystems",
"/sys/kernel/security/lsm",
}
}
func (linux) machineInfos() []machineInfoFunc {
return []machineInfoFunc{
linuxReadCPUInfo,
linuxReadKVMInfo,
}
}
func (linux linux) parseModules(files filesystem) ([]*KernelModule, error) {
if linux.vmType == targets.GVisor || linux.vmType == targets.Starnix {
return nil, nil
}
var modules []*KernelModule
re := regexp.MustCompile(`(\w+) ([0-9]+) .*(0[x|X][a-fA-F0-9]+)[^\n]*`)
modulesText, _ := files.ReadFile("/proc/modules")
for _, match := range re.FindAllSubmatch(modulesText, -1) {
name := string(match[1])
modAddr, err := strconv.ParseUint(string(match[3]), 0, 64)
if err != nil {
// /proc/modules is broken, bail out.
return nil, fmt.Errorf("module %v address parsing error: %w", name, err)
}
textAddr, err := linuxModuleTextAddr(files, name)
if err != nil {
// Module address unavailable, .text is probably 0. Skip this module.
continue
}
modSize, err := strconv.ParseUint(string(match[2]), 0, 64)
if err != nil {
// /proc/modules is broken, bail out.
return nil, fmt.Errorf("module %v size parsing error: %w", name, err)
}
offset := modAddr - textAddr
modules = append(modules, &KernelModule{
Name: name,
Addr: textAddr,
// The size is wrong as there is overlap in /proc/modules
// ex. module1['Addr'] + module1['Size'] > module2['Addr']
// runtime kernel doesn't export .text section size to /sys/module/*/sections/.text
// so we need to read it from elf
Size: modSize - offset,
})
}
_stext, _etext, err := linuxParseCoreKernel(files)
if err != nil {
return nil, err
}
modules = append(modules, &KernelModule{
Name: "",
Addr: _stext,
Size: _etext - _stext,
})
sort.Slice(modules, func(i, j int) bool {
return modules[i].Addr < modules[j].Addr
})
return modules, nil
}
func linuxModuleTextAddr(files filesystem, module string) (uint64, error) {
data, err := files.ReadFile("/sys/module/" + module + "/sections/.text")
if err != nil {
return 0, fmt.Errorf("could not read module %v .text address file: %w", module, err)
}
addrString := strings.TrimSpace(string(data))
addr, err := strconv.ParseUint(addrString, 0, 64)
if err != nil {
return 0, fmt.Errorf("address parsing error in %v: %w", module, err)
}
return addr, nil
}
func linuxParseCoreKernel(files filesystem) (uint64, uint64, error) {
_Text, _ := files.ReadFile("/proc/kallsyms")
re := regexp.MustCompile(`([a-fA-F0-9]+) T _stext\n`)
m := re.FindSubmatch(_Text)
if m == nil {
return 0, 0, fmt.Errorf("failed to get _stext symbol")
}
_stext, err := strconv.ParseUint("0x"+string(m[1]), 0, 64)
if err != nil {
return 0, 0, fmt.Errorf("address parsing error in /proc/kallsyms for _stext: %w", err)
}
// _etext symbol points to the _next_ section, so it has type of the next section.
// It can be at least T, D, or R in some cases:
// https://groups.google.com/g/syzkaller/c/LSx6YIK_Eeo
re = regexp.MustCompile(`([a-fA-F0-9]+) . _etext\n`)
m = re.FindSubmatch(_Text)
if m == nil {
return 0, 0, fmt.Errorf("failed to get _etext symbol")
}
_etext, err := strconv.ParseUint("0x"+string(m[1]), 0, 64)
if err != nil {
return 0, 0, fmt.Errorf("address parsing error in /proc/kallsyms for _etext: %w", err)
}
return _stext, _etext, nil
}
func linuxReadCPUInfo(files filesystem, w io.Writer) (string, error) {
data, err := files.ReadFile("/proc/cpuinfo")
if err != nil {
return "", fmt.Errorf("error reading CPU info:: %w", err)
}
keyIndices := make(map[string]int)
type keyValues struct {
key string
values []string
}
var info []keyValues
for s := bufio.NewScanner(bytes.NewReader(data)); s.Scan(); {
splitted := strings.Split(s.Text(), ":")
if len(splitted) != 2 {
continue
}
key := strings.TrimSpace(splitted[0])
val := strings.TrimSpace(splitted[1])
if idx, ok := keyIndices[key]; !ok {
idx = len(keyIndices)
keyIndices[key] = idx
info = append(info, keyValues{key, []string{val}})
} else {
info[idx].values = append(info[idx].values, val)
}
}
for _, kv := range info {
// It is guaranteed that len(vals) >= 1
key := kv.key
vals := kv.values
if allEqual(vals) {
fmt.Fprintf(w, "%-20s: %s\n", key, vals[0])
} else {
fmt.Fprintf(w, "%-20s: %s\n", key, strings.Join(vals, ", "))
}
}
return "CPU Info", nil
}
func allEqual(slice []string) bool {
for i := 1; i < len(slice); i++ {
if slice[i] != slice[0] {
return false
}
}
return true
}
func linuxReadKVMInfo(files filesystem, w io.Writer) (string, error) {
for _, module := range files.ReadDir("/sys/module") {
if !strings.HasPrefix(module, "kvm") {
continue
}
paramPath := path.Join("/sys", "module", module, "parameters")
fmt.Fprintf(w, "/sys/module/%s:\n", module)
for _, param := range files.ReadDir(paramPath) {
data, err := files.ReadFile(path.Join(paramPath, param))
if err != nil {
return "", fmt.Errorf("error reading KVM info: %w", err)
}
fmt.Fprintf(w, "\t%s: %s", param, data)
}
w.Write([]byte{'\n'})
}
return "KVM", nil
}
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