94 lines
2.5 KiB
Go
94 lines
2.5 KiB
Go
//go:build !windows && !linux
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// +build !windows,!linux
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package main
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import (
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"os"
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"os/exec"
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"os/user"
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"path/filepath"
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"runtime"
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"strconv"
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"golang.org/x/sys/unix"
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"github.com/jedisct1/dlog"
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)
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func (proxy *Proxy) dropPrivilege(userStr string, fds []*os.File) {
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if os.Geteuid() != 0 {
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dlog.Fatal("Root privileges are required in order to switch to a different user. Maybe try again with 'sudo'")
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}
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userInfo, err := user.Lookup(userStr)
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args := os.Args
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if err != nil {
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uid, err2 := strconv.Atoi(userStr)
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if err2 != nil || uid <= 0 {
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dlog.Fatalf(
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"Unable to retrieve any information about user [%s]: [%s] - Remove the user_name directive from the configuration file in order to avoid identity switch",
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userStr,
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err,
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)
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}
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dlog.Warnf(
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"Unable to retrieve any information about user [%s]: [%s] - Switching to user id [%v] with the same group id, as [%v] looks like a user id. But you should remove or fix the user_name directive in the configuration file if possible",
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userStr,
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err,
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uid,
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uid,
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)
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userInfo = &user.User{Uid: userStr, Gid: userStr}
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}
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uid, err := strconv.Atoi(userInfo.Uid)
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if err != nil {
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dlog.Fatal(err)
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}
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gid, err := strconv.Atoi(userInfo.Gid)
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if err != nil {
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dlog.Fatal(err)
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}
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execPath, err := exec.LookPath(args[0])
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if err != nil {
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dlog.Fatalf("Unable to get the path to the dnscrypt-proxy executable file: [%s]", err)
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}
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path, err := filepath.Abs(execPath)
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if err != nil {
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dlog.Fatal(err)
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}
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if err := ServiceManagerReadyNotify(); err != nil {
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dlog.Fatal(err)
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}
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args = append(args, "-child")
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dlog.Notice("Dropping privileges")
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runtime.LockOSThread()
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if err := unix.Setgroups([]int{}); err != nil {
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dlog.Fatalf("Unable to drop additional groups: %s", err)
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}
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if err := unix.Setgid(gid); err != nil {
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dlog.Fatalf("Unable to drop group privileges: %s", err)
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}
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if err := unix.Setuid(uid); err != nil {
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dlog.Fatalf("Unable to drop user privileges: %s", err)
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}
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for i, fd := range fds {
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if fd.Fd() >= InheritedDescriptorsBase {
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dlog.Fatal("Duplicated file descriptors are above base")
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}
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if err := unix.Dup2(int(fd.Fd()), int(InheritedDescriptorsBase+uintptr(i))); err != nil {
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dlog.Fatalf("Unable to clone file descriptor: [%s]", err)
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}
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if _, err := unix.FcntlInt(fd.Fd(), unix.F_SETFD, unix.FD_CLOEXEC); err != nil {
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dlog.Fatalf("Unable to set the close on exec flag: [%s]", err)
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}
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}
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err = unix.Exec(path, args, os.Environ())
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dlog.Fatalf("Unable to reexecute [%s]: [%s]", path, err)
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os.Exit(1)
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}
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