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145 lines
3.1 KiB
Go
145 lines
3.1 KiB
Go
// +build linux
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package iface
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// Holds logic to check existence of Wireguard kernel module
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// Copied from https://github.com/paultag/go-modprobe
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import (
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"debug/elf"
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"fmt"
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"golang.org/x/sys/unix"
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"os"
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"path/filepath"
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"strings"
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)
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var (
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// get the root directory for the kernel modules. If this line panics,
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// it's because getModuleRoot has failed to get the uname of the running
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// kernel (likely a non-POSIX system, but maybe a broken kernel?)
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moduleRoot = getModuleRoot()
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)
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// Get the module root (/lib/modules/$(uname -r)/)
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func getModuleRoot() string {
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uname := unix.Utsname{}
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if err := unix.Uname(&uname); err != nil {
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panic(err)
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}
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i := 0
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for ; uname.Release[i] != 0; i++ {
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}
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return filepath.Join(
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"/lib/modules",
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string(uname.Release[:i]),
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)
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}
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// modName will, given a file descriptor to a Kernel Module (.ko file), parse the
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// binary to get the module name. For instance, given a handle to the file at
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// `kernel/drivers/usb/gadget/legacy/g_ether.ko`, return `g_ether`.
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func modName(file *os.File) (string, error) {
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f, err := elf.NewFile(file)
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if err != nil {
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return "", err
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}
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syms, err := f.Symbols()
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if err != nil {
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return "", err
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}
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for _, sym := range syms {
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if strings.Compare(sym.Name, "__this_module") == 0 {
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section := f.Sections[sym.Section]
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data, err := section.Data()
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if err != nil {
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return "", err
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}
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if len(data) < 25 {
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return "", fmt.Errorf("modprobe: data is short, __this_module is '%s'", data)
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}
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data = data[24:]
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i := 0
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for ; data[i] != 0x00; i++ {
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}
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return string(data[:i]), nil
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}
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}
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return "", fmt.Errorf("No name found. Is this a .ko or just an ELF?")
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}
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// Open every single kernel module under the root, and parse the ELF headers to
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// extract the module name.
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func elfMap(root string) (map[string]string, error) {
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ret := map[string]string{}
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err := filepath.Walk(
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root,
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func(path string, info os.FileInfo, err error) error {
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if err != nil {
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// skip broken files
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return nil
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}
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if !info.Mode().IsRegular() {
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return nil
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}
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fd, err := os.Open(path)
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if err != nil {
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return err
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}
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defer fd.Close()
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name, err := modName(fd)
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if err != nil {
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/* For now, let's just ignore that and avoid adding to it */
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return nil
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}
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ret[name] = path
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return nil
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})
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if err != nil {
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return nil, err
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}
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return ret, nil
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}
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// Open every single kernel module under the kernel module directory
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// (/lib/modules/$(uname -r)/), and parse the ELF headers to extract the
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// module name.
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func generateMap() (map[string]string, error) {
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return elfMap(moduleRoot)
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}
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// WireguardModExists returns true if Wireguard kernel module exists.
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func WireguardModExists() bool {
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_, err := resolveModName("wireguard")
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return err == nil
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}
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// resolveModName will, given a module name (such as `wireguard`) return an absolute
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// path to the .ko that provides that module.
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func resolveModName(name string) (string, error) {
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paths, err := generateMap()
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if err != nil {
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return "", err
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}
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fsPath := paths[name]
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if !strings.HasPrefix(fsPath, moduleRoot) {
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return "", fmt.Errorf("module isn't in the module directory")
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}
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return fsPath, nil
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}
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