miracle091/dnscrypt-proxy
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Code Issues Releases Wiki Activity

Of course, things have to be different on Linux

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This commit is contained in:
Frank Denis 2019-09-07 16:45:11 +02:00
parent 5c9c20c974
commit 3e10fc917f
2 changed files with 91 additions and 2 deletions
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89
dnscrypt-proxy/privilege_linux.go Normal file
View File

@ -0,0 +1,89 @@
package main
import (
"os"
"os/exec"
"os/user"
"path/filepath"
"runtime"
"strconv"
"syscall"
"golang.org/x/sys/unix"
"github.com/jedisct1/dlog"
)
func (proxy *Proxy) dropPrivilege(userStr string, fds []*os.File) {
currentUser, err := user.Current()
if err != nil && currentUser.Uid != "0" {
dlog.Fatal("Root privileges are required in order to switch to a different user. Maybe try again with 'sudo'")
}
userInfo, err := user.Lookup(userStr)
args := os.Args
if err != nil {
uid, err2 := strconv.Atoi(userStr)
if err2 != nil || uid <= 0 {
dlog.Fatalf("Unable to retrieve any information about user [%s]: [%s] - Remove the user_name directive from the configuration file in order to avoid identity switch", userStr, err)
}
dlog.Warnf("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", userStr, err, uid, uid)
userInfo = &user.User{Uid: userStr, Gid: userStr}
}
uid, err := strconv.Atoi(userInfo.Uid)
if err != nil {
dlog.Fatal(err)
}
gid, err := strconv.Atoi(userInfo.Gid)
if err != nil {
dlog.Fatal(err)
}
execPath, err := exec.LookPath(args[0])
if err != nil {
dlog.Fatalf("Unable to get the path to the dnscrypt-proxy executable file: [%s]", err)
}
path, err := filepath.Abs(execPath)
if err != nil {
dlog.Fatal(err)
}
ServiceManagerReadyNotify()
args = append(args, "-child")
dlog.Notice("Dropping privileges")
runtime.LockOSThread()
if _, _, rcode := syscall.RawSyscall(syscall.SYS_SETGROUPS, uintptr(0), uintptr(0), 0); rcode != 0 {
dlog.Fatalf("Unable to drop additional groups: [%s]", rcode.Error())
}
if _, _, rcode := syscall.RawSyscall(syscall.SYS_SETGID, uintptr(gid), 0, 0); rcode != 0 {
dlog.Fatalf("Unable to drop group privileges: [%s]", rcode.Error())
}
if _, _, rcode := syscall.RawSyscall(syscall.SYS_SETUID, uintptr(uid), 0, 0); rcode != 0 {
dlog.Fatalf("Unable to drop user privileges: [%s]", rcode.Error())
}
maxfd := uintptr(0)
for _, fd := range fds {
if fd.Fd() > maxfd {
maxfd = fd.Fd()
}
}
fdbase := maxfd + 1
for i, fd := range fds {
if err := unix.Dup2(int(fd.Fd()), int(fdbase+uintptr(i))); err != nil {
dlog.Fatalf("Unable to clone file descriptor: [%s]", err)
}
if _, err := unix.FcntlInt(fd.Fd(), unix.F_SETFD, unix.FD_CLOEXEC); err != nil {
dlog.Fatalf("Unable to set the close on exec flag: [%s]", err)
}
}
for i := range fds {
if err := unix.Dup2(int(fdbase+uintptr(i)), int(i)+3); err != nil {
dlog.Fatalf("Unable to reassign descriptor: [%s]", err)
}
}
err = unix.Exec(path, args, os.Environ())
dlog.Fatalf("Unable to reexecute [%s]: [%s]", path, err)
os.Exit(1)
}

4
dnscrypt-proxy/privilege_others.go
View File

@ -1,4 +1,4 @@
// +build !windows
// +build !windows,!linux
package main
@ -59,7 +59,7 @@ func (proxy *Proxy) dropPrivilege(userStr string, fds []*os.File) {
dlog.Fatalf("Unable to drop additional groups: %s", err)
}
if err := unix.Setgid(gid); err != nil {
dlog.Fatalf("Unable to drop user privileges: %s", err)
dlog.Fatalf("Unable to drop group privileges: %s", err)
}
if err := unix.Setuid(uid); err != nil {
dlog.Fatalf("Unable to drop user privileges: %s", err)