Drop support for running nix-worker in "slave" mode
AFAIK nobody uses this, setuid binaries are evil, and there is no good reason why people can't just run the daemon.
This commit is contained in:
Eelco Dolstra
parent
7586095504
commit
522ecab9b8
6 changed files with 9 additions and 146 deletions
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@ -201,10 +201,8 @@ flag, e.g. <literal>--option gc-keep-outputs false</literal>.</para>
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under the uid of the Nix process (that is, the uid of the caller
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if <envar>NIX_REMOTE</envar> is empty, the uid under which the Nix
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daemon runs if <envar>NIX_REMOTE</envar> is
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<literal>daemon</literal>, or the uid that owns the setuid
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<command>nix-worker</command> program if <envar>NIX_REMOTE</envar>
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is <literal>slave</literal>). Obviously, this should not be used
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in multi-user settings with untrusted users.</para>
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<literal>daemon</literal>). Obviously, this should not be used in
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multi-user settings with untrusted users.</para>
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</listitem>
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@ -125,8 +125,7 @@ static void initAndRun(int argc, char * * argv)
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/* There is no privacy in the Nix system ;-) At least not for
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now. In particular, store objects should be readable by
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everybody. This prevents nasty surprises when using a shared
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store (with the setuid() hack). */
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everybody. */
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umask(0022);
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/* Process the NIX_LOG_TYPE environment variable. */
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@ -218,56 +217,6 @@ static void initAndRun(int argc, char * * argv)
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}
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bool setuidMode = false;
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static void setuidInit()
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{
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/* Don't do anything if this is not a setuid binary. */
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if (getuid() == geteuid() && getgid() == getegid()) return;
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uid_t nixUid = geteuid();
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gid_t nixGid = getegid();
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setuidCleanup();
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/* Don't trust the current directory. */
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if (chdir("/") == -1) abort();
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/* Set the real (and preferably also the save) uid/gid to the
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effective uid/gid. This matters mostly when we're not using
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build-users (bad!), since some builders (like Perl) complain
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when real != effective.
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On systems where setresuid is unavailable, we can't drop the
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saved uid/gid. This means that we could go back to the
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original real uid (i.e., the uid of the caller). That's not
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really a problem, except maybe when we execute a builder and
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we're not using build-users. In that case, the builder may be
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able to switch to the uid of the caller and possibly do bad
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stuff. But note that when not using build-users, the builder
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could also modify the Nix executables (say, replace them by a
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Trojan horse), so the problem is already there. */
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#if HAVE_SETRESUID
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if (setresuid(nixUid, nixUid, nixUid)) abort();
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if (setresgid(nixGid, nixGid, nixGid)) abort();
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#elif HAVE_SETREUID
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/* Note: doesn't set saved uid/gid! */
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fprintf(stderr, "warning: cannot set saved uid\n");
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if (setreuid(nixUid, nixUid)) abort();
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if (setregid(nixGid, nixGid)) abort();
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#else
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/* Note: doesn't set real and saved uid/gid! */
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fprintf(stderr, "warning: cannot set real and saved uids\n");
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if (setuid(nixUid)) abort();
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if (setgid(nixGid)) abort();
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#endif
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setuidMode = true;
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}
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/* Called when the Boehm GC runs out of memory. */
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static void * oomHandler(size_t requested)
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{
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@ -298,11 +247,6 @@ int main(int argc, char * * argv)
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argvSaved = argv;
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/* If we're setuid, then we need to take some security precautions
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right away. */
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if (argc == 0) abort();
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setuidInit();
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/* Turn on buffering for cerr. */
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#if HAVE_PUBSETBUF
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std::cerr.rdbuf()->pubsetbuf(buf, sizeof(buf));
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@ -44,9 +44,6 @@ template<class N> N getIntArg(const string & opt,
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/* Show the manual page for the specified program. */
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void showManPage(const string & name);
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/* Whether we're running setuid. */
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extern bool setuidMode;
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extern volatile ::sig_atomic_t blockInt;
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/* Exit code of the program. */
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@ -50,16 +50,12 @@ void RemoteStore::openConnection(bool reserveSpace)
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string remoteMode = getEnv("NIX_REMOTE");
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if (remoteMode == "slave")
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/* Fork off a setuid worker to do the privileged work. */
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forkSlave();
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else if (remoteMode == "daemon")
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if (remoteMode == "daemon")
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/* Connect to a daemon that does the privileged work for
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us. */
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connectToDaemon();
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connectToDaemon();
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else
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throw Error(format("invalid setting for NIX_REMOTE, `%1%'")
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% remoteMode);
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throw Error(format("invalid setting for NIX_REMOTE, `%1%'") % remoteMode);
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from.fd = fdSocket;
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to.fd = fdSocket;
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@ -88,54 +84,6 @@ void RemoteStore::openConnection(bool reserveSpace)
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}
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void RemoteStore::forkSlave()
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{
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int sockets[2];
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if (socketpair(AF_UNIX, SOCK_STREAM, 0, sockets) == -1)
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throw SysError("cannot create sockets");
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fdSocket = sockets[0];
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AutoCloseFD fdChild = sockets[1];
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/* Start the worker. */
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Path worker = getEnv("NIX_WORKER");
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if (worker == "")
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worker = settings.nixBinDir + "/nix-worker";
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child = fork();
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switch (child) {
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case -1:
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throw SysError("unable to fork");
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case 0:
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try { /* child */
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if (dup2(fdChild, STDOUT_FILENO) == -1)
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throw SysError("dupping write side");
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if (dup2(fdChild, STDIN_FILENO) == -1)
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throw SysError("dupping read side");
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close(fdSocket);
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close(fdChild);
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execlp(worker.c_str(), worker.c_str(), "--slave", NULL);
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throw SysError(format("executing `%1%'") % worker);
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} catch (std::exception & e) {
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std::cerr << format("child error: %1%\n") % e.what();
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}
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quickExit(1);
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}
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fdChild.close();
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}
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void RemoteStore::connectToDaemon()
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{
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fdSocket = socket(PF_UNIX, SOCK_STREAM, 0);
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@ -893,33 +893,15 @@ static void daemonLoop()
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void run(Strings args)
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{
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bool slave = false;
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bool daemon = false;
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for (Strings::iterator i = args.begin(); i != args.end(); ) {
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string arg = *i++;
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if (arg == "--slave") slave = true;
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if (arg == "--daemon") daemon = true;
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if (arg == "--daemon") /* ignored for backwards compatibility */;
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}
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if (slave) {
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/* This prevents us from receiving signals from the terminal
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when we're running in setuid mode. */
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if (setsid() == -1)
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throw SysError(format("creating a new session"));
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processConnection();
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}
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else if (daemon) {
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if (setuidMode)
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throw Error("daemon cannot be started in setuid mode");
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chdir("/");
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daemonLoop();
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}
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else
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throw Error("must be run in either --slave or --daemon mode");
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chdir("/");
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daemonLoop();
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}
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@ -1,11 +1,5 @@
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source common.sh
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echo '*** testing slave mode ***'
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clearStore
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clearManifests
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NIX_REMOTE_=slave $SHELL ./user-envs.sh
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echo '*** testing daemon mode ***'
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clearStore
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clearManifests
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startDaemon
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