path: root/utils/fakeauth.c

/* fakeauth -- proxy auth server to lie to users about what their IDs are
   Copyright (C) 2002 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2, or (at
   your option) any later version.

   This program is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

#include <hurd.h>
#include <hurd/auth.h>
#include <hurd/interrupt.h>
#include <hurd/ports.h>
#include <idvec.h>
#include <unistd.h>
#include <sys/wait.h>
#include <spawn.h>
#include <assert.h>
#include <argp.h>
#include <error.h>
#include "auth_S.h"
#include "auth_request_U.h"
#include "interrupt_S.h"

/* Auth handles are server ports with sets of ids.  */
struct authhandle
  {
    struct port_info pi;
    struct idvec euids, egids, auids, agids;
  };

struct port_bucket *auth_bucket;
struct port_class *authhandle_portclass;

/* Create a new auth port.  */

static error_t
create_authhandle (struct authhandle **new)
{
  error_t err = ports_create_port (authhandle_portclass, auth_bucket,
				   sizeof **new, new);
  if (! err)
    bzero (&(*new)->euids, (void *) &(*new)[1] - (void *) &(*new)->euids);
  return err;
}

/* Clean up a dead auth port.  */

static void
destroy_authhandle (void *p)
{
  struct authhandle *h = p;
  idvec_free_contents (&h->euids);
  idvec_free_contents (&h->egids);
  idvec_free_contents (&h->auids);
  idvec_free_contents (&h->agids);
}

/* Called by server stub functions.  */

authhandle_t
auth_port_to_handle (auth_t auth)
{
  return ports_lookup_port (auth_bucket, auth, authhandle_portclass);
}

/* id management.  */

static inline void
idvec_copyout (struct idvec *idvec, uid_t **ids, uid_t *nids)
{
  if (idvec->num > *nids)
    *ids = idvec->ids;
  else
    memcpy (*ids, idvec->ids, idvec->num * sizeof *ids);
  *nids = idvec->num;
}

#define C(auth, ids)	idvec_copyout (&auth->ids, ids, n##ids)
#define OUTIDS(auth)	(C (auth, euids), C (auth, egids), \
			 C (auth, auids), C (auth, agids))

/* Implement auth_getids as described in <hurd/auth.defs>. */
kern_return_t
S_auth_getids (struct authhandle *auth,
	       uid_t **euids,
	       u_int *neuids,
	       uid_t **auids,
	       u_int *nauids,
	       uid_t **egids,
	       u_int *negids,
	       uid_t **agids,
	       u_int *nagids)
{
  if (! auth)
    return EOPNOTSUPP;

  OUTIDS (auth);

  return 0;
}

/* Implement auth_makeauth as described in <hurd/auth.defs>. */
kern_return_t
S_auth_makeauth (struct authhandle *auth,
		 mach_port_t *authpts, u_int nauths,
		 uid_t *euids, u_int neuids,
		 uid_t *auids, u_int nauids,
		 uid_t *egids, u_int negids,
		 uid_t *agids, u_int nagids,
		 mach_port_t *newhandle)
{
  struct authhandle *newauth, *auths[1 + nauths];
  int hasroot = 0;
  error_t err;
  u_int i, j;

  if (!auth)
    return EOPNOTSUPP;

  auths[0] = auth;

  /* Fetch the auth structures for all the ports passed in. */
  for (i = 0; i < nauths; i++)
    auths[i + 1] = auth_port_to_handle (authpts[i]);

  ++nauths;

  /* Verify that the union of the handles passed in either contains euid 0
     (root), or contains all the requested ids.  */

#define isuid(uid, auth) \
  (idvec_contains (&(auth)->euids, uid) \
   || idvec_contains (&(auth)->auids, uid))
#define groupmember(gid, auth) \
  (idvec_contains (&(auth)->egids, gid) \
   || idvec_contains (&(auth)->agids, gid))
#define isroot(auth)		isuid (0, auth)

  for (i = 0; i < nauths; i++)
    if (auths[i] && isroot (auths[i]))
      {
	hasroot = 1;
	break;
      }

  if (!hasroot)
    {
      int has_it;

      for (i = 0; i < neuids; i++)
	{
	  has_it = 0;
	  for (j = 0; j < nauths; j++)
	    if (auths[j] && isuid (euids[i], auths[j]))
	      {
		has_it = 1;
		break;
	      }
	  if (!has_it)
	    goto eperm;
	}

      for (i = 0; i < nauids; i++)
	{
	  has_it = 0;
	  for (j = 0; j < nauths; j++)
	    if (auths[j] && isuid (auids[i], auths[j]))
	      {
		has_it = 1;
		break;
	      }
	  if (!has_it)
	    goto eperm;
	}

      for (i = 0; i < negids; i++)
	{
	  has_it = 0;
	  for (j = 0; j < nauths; j++)
	    if (auths[j] && groupmember (egids[i], auths[j]))
	      {
		has_it = 1;
		break;
	      }
	  if (!has_it)
	    goto eperm;
	}

      for (i = 0; i < nagids; i++)
	{
	  has_it = 0;
	  for (j = 0; j < nauths; j++)
	    if (auths[j] && groupmember (agids[i], auths[j]))
	      {
		has_it = 1;
		break;
	      }
	  if (!has_it)
	    goto eperm;
	}
    }

  err = create_authhandle (&newauth);

  /* Create a new handle with the specified ids.  */

#define MERGE S (euids); S (egids); S (auids); S (agids);
#define S(uids) if (!err) err = idvec_merge_ids (&newauth->uids, uids, n##uids)

  MERGE;

#undef S

  if (! err)
    {
      for (j = 1; j < nauths; ++j)
	mach_port_deallocate (mach_task_self (), authpts[j - 1]);
      *newhandle = ports_get_right (newauth);
      ports_port_deref (newauth);
    }

  for (j = 1; j < nauths; j++)
    if (auths[j])
      ports_port_deref (auths[j]);
  return err;

 eperm:
  for (j = 1; j < nauths; j++)
    if (auths[j])
      ports_port_deref (auths[j]);
  return EPERM;
}


/* This is our original auth port, where we will send all proxied
   authentication requests.  */
static auth_t real_auth_port;

kern_return_t
S_auth_user_authenticate (struct authhandle *userauth,
			  mach_port_t reply,
			  mach_msg_type_name_t reply_type,
			  mach_port_t rendezvous,
			  mach_port_t *newport,
			  mach_msg_type_name_t *newporttype)
{
  if (! userauth)
    return EOPNOTSUPP;

  if (rendezvous == MACH_PORT_DEAD) /* Port died in transit.  */
    return EINVAL;

  return auth_user_authenticate_request (real_auth_port, reply, reply_type,
					 rendezvous, MACH_MSG_TYPE_MOVE_SEND)
    ? : MIG_NO_REPLY;
}

kern_return_t
S_auth_server_authenticate (struct authhandle *serverauth,
			    mach_port_t reply,
			    mach_msg_type_name_t reply_type,
			    mach_port_t rendezvous,
			    mach_port_t newport,
			    mach_msg_type_name_t newport_type,
			    uid_t **euids,
			    u_int *neuids,
			    uid_t **auids,
			    u_int *nauids,
			    uid_t **egids,
			    u_int *negids,
			    uid_t **agids,
			    u_int *nagids)
{
  if (! serverauth)
    return EOPNOTSUPP;

  if (rendezvous == MACH_PORT_DEAD) /* Port died in transit.  */
    return EINVAL;

  return auth_server_authenticate_request (real_auth_port,
					   reply, reply_type,
					   rendezvous, MACH_MSG_TYPE_MOVE_SEND,
					   newport, newport_type)
    ? : MIG_NO_REPLY;
}

kern_return_t
S_interrupt_operation (mach_port_t port, mach_port_seqno_t seqno)
{
  return interrupt_operation (real_auth_port, 0);
}

static int
auth_demuxer (mach_msg_header_t *inp, mach_msg_header_t *outp)
{
  extern int auth_server (mach_msg_header_t *inp, mach_msg_header_t *outp);
  extern int interrupt_server (mach_msg_header_t *inp, mach_msg_header_t *);
  return (auth_server (inp, outp) ||
	  interrupt_server (inp, outp) ||
	  ports_notify_server (inp, outp));
}


static any_t
handle_auth_requests (any_t ignored)
{
  while (1)
    ports_manage_port_operations_multithread (auth_bucket, auth_demuxer,
					      30 * 1000, 0, 0);
  return 0;
}

int
main (int argc, char **argv)
{
  error_t err;
  struct authhandle *firstauth;
  auth_t authport;
  pid_t child;
  int status;
  int argi;

  /* Parse our options.  */
  error_t parse_opt (int key, char *arg, struct argp_state *state)
    {
      switch (key)
        {
        case ARGP_KEY_NO_ARGS:
          argp_usage (state);
          return EINVAL;
        default:
          return ARGP_ERR_UNKNOWN;
        }
      return 0;
    }
  struct argp argp = { 0, parse_opt, "COMMAND...", "\
Run COMMAND with a fake authentication handle that claims to be root or \
any arbitrary identity derived from that handle, but in fact is always just \
a proxy for your real authentication handle.  This means that all processes \
created by the COMMAND will have your privileges, even though it may \
believe it has restricted them to different identities or no identity at all.\
" };

  argp_parse (&argp, argc, argv, ARGP_IN_ORDER, &argi, 0);

  auth_bucket = ports_create_bucket ();
  authhandle_portclass = ports_create_class (&destroy_authhandle, 0);

  /* Create the initial root auth handle.  */
  err = create_authhandle (&firstauth);
  assert_perror (err);
  idvec_add (&firstauth->euids, 0);
  idvec_add (&firstauth->auids, 0);
  idvec_add (&firstauth->auids, 0);
  idvec_merge (&firstauth->egids, &firstauth->euids);
  idvec_merge (&firstauth->agids, &firstauth->auids);

  /* Get a send right for it.  */
  authport = ports_get_right (firstauth);
  err = mach_port_insert_right (mach_task_self (), authport, authport,
				MACH_MSG_TYPE_MAKE_SEND);
  assert_perror (err);
  ports_port_deref (firstauth);

  /* Stash our original auth port for later use.  */
  real_auth_port = getauth ();

  /* Start handling auth requests on our fake handles.  */
  cthread_detach (cthread_fork (&handle_auth_requests, (any_t)0));

  /* Now we start faking ourselves out.  This will immediately
     reauthenticate all our descriptors through our proxy auth port.
     The POSIXoid calls we make below will continue to use the fake
     port and pass it on to the child.  */
  if (setauth (authport))
    error (2, errno, "Cannot switch to fake auth handle");
  mach_port_deallocate (mach_task_self (), authport);

  if (posix_spawnp (&child, argv[argi], NULL, NULL, &argv[argi], environ))
    error (3, errno, "cannot run %s", argv[1]);

  if (waitpid (child, &status, 0) != child)
    error (4, errno, "waitpid on %d", child);

  if (WIFSIGNALED (status))
    error (WTERMSIG (status) + 128, 0,
	   "%s for child %d", strsignal (WTERMSIG (status)), child);
  if (WEXITSTATUS (status) != 0)
    error (WEXITSTATUS (status), 0,
	   "Error %d for child %d", WEXITSTATUS (status), child);

  return 0;
}