forked from u-root/u-root
/
kmodule_linux.go
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/
kmodule_linux.go
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// Copyright 2017-2018 the u-root Authors. All rights reserved
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package kmodule interfaces with Linux kernel modules.
//
// kmodule allows loading and unloading kernel modules with dependencies, as
// well as locating them through probing.
package kmodule
import (
"bufio"
"bytes"
"fmt"
"io"
"io/ioutil"
"os"
"path"
"path/filepath"
"strings"
"golang.org/x/sys/unix"
)
// Flags to finit_module(2) / FileInit.
const (
// Ignore symbol version hashes.
MODULE_INIT_IGNORE_MODVERSIONS = 0x1
// Ignore kernel version magic.
MODULE_INIT_IGNORE_VERMAGIC = 0x2
)
// Init loads the kernel module given by image with the given options.
func Init(image []byte, opts string) error {
return unix.InitModule(image, opts)
}
// FileInit loads the kernel module contained by `f` with the given opts and
// flags.
//
// FileInit falls back to Init when the finit_module(2) syscall is not available.
func FileInit(f *os.File, opts string, flags uintptr) error {
err := unix.FinitModule(int(f.Fd()), opts, int(flags))
if err == unix.ENOSYS {
if flags != 0 {
return err
}
// Fall back to regular init_module(2).
img, err := ioutil.ReadAll(f)
if err != nil {
return err
}
return Init(img, opts)
}
return err
}
// Delete removes a kernel module.
func Delete(name string, flags uintptr) error {
return unix.DeleteModule(name, int(flags))
}
type modState uint8
const (
unloaded modState = iota
loading
loaded
builtin
)
type dependency struct {
state modState
deps []string
}
type depMap map[string]*dependency
// ProbeOpts contains optional parameters to Probe.
//
// An empty ProbeOpts{} should lead to the default behavior.
type ProbeOpts struct {
DryRunCB func(string)
RootDir string
KVer string
IgnoreProcMods bool
}
// Probe loads the given kernel module and its dependencies.
// It is calls ProbeOptions with the default ProbeOpts.
func Probe(name string, modParams string) error {
return ProbeOptions(name, modParams, ProbeOpts{})
}
// ProbeOptions loads the given kernel module and its dependencies.
// This functions takes ProbeOpts.
func ProbeOptions(name, modParams string, opts ProbeOpts) error {
deps, err := genDeps(opts)
if err != nil {
return fmt.Errorf("could not generate dependency map %v", err)
}
modPath, err := findModPath(name, deps)
if err != nil {
return fmt.Errorf("could not find module path %q: %v", name, err)
}
dep := deps[modPath]
if dep.state == builtin || dep.state == loaded {
return nil
}
dep.state = loading
for _, d := range dep.deps {
if err := loadDeps(d, deps, opts); err != nil {
return err
}
}
if err := loadModule(modPath, modParams, opts); err != nil {
return err
}
return nil
}
func checkBuiltin(moduleDir string, deps depMap) error {
f, err := os.Open(filepath.Join(moduleDir, "modules.builtin"))
if os.IsNotExist(err) {
return nil
} else if err != nil {
return fmt.Errorf("could not open builtin file: %v", err)
}
defer f.Close()
scanner := bufio.NewScanner(f)
for scanner.Scan() {
txt := scanner.Text()
modPath := filepath.Join(moduleDir, strings.TrimSpace(txt))
if deps[modPath] == nil {
deps[modPath] = new(dependency)
}
deps[modPath].state = builtin
}
return scanner.Err()
}
func genDeps(opts ProbeOpts) (depMap, error) {
deps := make(depMap)
rel := opts.KVer
if rel == "" {
var u unix.Utsname
if err := unix.Uname(&u); err != nil {
return nil, fmt.Errorf("could not get release (uname -r): %v", err)
}
rel = string(u.Release[:bytes.IndexByte(u.Release[:], 0)])
}
var moduleDir string
for _, n := range []string{"/lib/modules", "/usr/lib/modules"} {
moduleDir = filepath.Join(opts.RootDir, n, strings.TrimSpace(rel))
if _, err := os.Stat(moduleDir); err == nil {
break
}
}
f, err := os.Open(filepath.Join(moduleDir, "modules.dep"))
if err != nil {
return nil, fmt.Errorf("could not open dependency file: %v", err)
}
defer f.Close()
scanner := bufio.NewScanner(f)
for scanner.Scan() {
txt := scanner.Text()
nameDeps := strings.Split(txt, ":")
modPath, modDeps := nameDeps[0], nameDeps[1]
modPath = filepath.Join(moduleDir, strings.TrimSpace(modPath))
var dependency dependency
if len(modDeps) > 0 {
for _, dep := range strings.Split(strings.TrimSpace(modDeps), " ") {
dependency.deps = append(dependency.deps, filepath.Join(moduleDir, dep))
}
}
deps[modPath] = &dependency
}
if err := scanner.Err(); err != nil {
return nil, err
}
if err = checkBuiltin(moduleDir, deps); err != nil {
return nil, err
}
if !opts.IgnoreProcMods {
fm, err := os.Open("/proc/modules")
if err == nil {
defer fm.Close()
genLoadedMods(fm, deps)
}
}
return deps, nil
}
func findModPath(name string, m depMap) (string, error) {
for mp := range m {
if path.Base(mp) == name+".ko" {
return mp, nil
}
}
return "", fmt.Errorf("Could not find path for module %q", name)
}
func loadDeps(path string, m depMap, opts ProbeOpts) error {
dependency, ok := m[path]
if !ok {
return fmt.Errorf("could not find dependency %q", path)
}
if dependency.state == loading {
return fmt.Errorf("circular dependency! %q already LOADING", path)
} else if (dependency.state == loaded) || (dependency.state == builtin) {
return nil
}
m[path].state = loading
for _, dep := range dependency.deps {
if err := loadDeps(dep, m, opts); err != nil {
return err
}
}
// done with dependencies, load module
if err := loadModule(path, "", opts); err != nil {
return err
}
m[path].state = loaded
return nil
}
func loadModule(path, modParams string, opts ProbeOpts) error {
if opts.DryRunCB != nil {
opts.DryRunCB(path)
return nil
}
f, err := os.Open(path)
if err != nil {
return err
}
defer f.Close()
if err := FileInit(f, modParams, 0); err != nil && err != unix.EEXIST {
return err
}
return nil
}
func genLoadedMods(r io.Reader, deps depMap) error {
scanner := bufio.NewScanner(r)
for scanner.Scan() {
arr := strings.Split(scanner.Text(), " ")
name := strings.Replace(arr[0], "_", "-", -1)
modPath, err := findModPath(name, deps)
if err != nil {
return fmt.Errorf("could not find module path %q: %v", name, err)
}
if deps[modPath] == nil {
deps[modPath] = new(dependency)
}
deps[modPath].state = loaded
}
return scanner.Err()
}