newlib/winsup/cygwin/security.cc

/* security.cc: NT security functions

   Copyright 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005 Red Hat, Inc.

   Originaly written by Gunther Ebert, gunther.ebert@ixos-leipzig.de
   Completely rewritten by Corinna Vinschen <corinna@vinschen.de>

This file is part of Cygwin.

This software is a copyrighted work licensed under the terms of the
Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
details. */

#include "winsup.h"
#include <grp.h>
#include <pwd.h>
#include <unistd.h>
#include <stdlib.h>
#include <limits.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/acl.h>
#include <ctype.h>
#include <winnls.h>
#include <wingdi.h>
#include <winuser.h>
#include <wininet.h>
#include <ntsecapi.h>
#include <subauth.h>
#include <aclapi.h>
#include "cygerrno.h"
#include "security.h"
#include "path.h"
#include "fhandler.h"
#include "dtable.h"
#include "pinfo.h"
#include "cygheap.h"
#include <ntdef.h>
#include "ntdll.h"
#include "lm.h"
#include "pwdgrp.h"

bool allow_ntsec;
/* allow_smbntsec is handled exclusively in path.cc (path_conv::check).
   It's defined here because of it's strong relationship to allow_ntsec. */
bool allow_smbntsec;
bool allow_traverse;

cygsid *
cygsidlist::alloc_sids (int n)
{
  if (n > 0)
    return (cygsid *) cmalloc (HEAP_STR, n * sizeof (cygsid));
  else
    return NULL;
}

void
cygsidlist::free_sids ()
{
  if (sids)
    cfree (sids);
  sids = NULL;
  count = maxcount = 0;
  type = cygsidlist_empty;
}

extern "C" void
cygwin_set_impersonation_token (const HANDLE hToken)
{
  debug_printf ("set_impersonation_token (%d)", hToken);
  cygheap->user.external_token = hToken == INVALID_HANDLE_VALUE ? NO_IMPERSONATION : hToken;
  return;
}

void
extract_nt_dom_user (const struct passwd *pw, char *domain, char *user)
{
  char *d, *u, *c;

  domain[0] = 0;
  strlcpy (user, pw->pw_name, UNLEN + 1);
  debug_printf ("pw_gecos %x (%s)", pw->pw_gecos, pw->pw_gecos);

  if ((d = strstr (pw->pw_gecos, "U-")) != NULL &&
      (d == pw->pw_gecos || d[-1] == ','))
    {
      c = strechr (d + 2, ',');
      if ((u = strechr (d + 2, '\\')) >= c)
	u = d + 1;
      else if (u - d <= INTERNET_MAX_HOST_NAME_LENGTH + 2)
	strlcpy (domain, d + 2, u - d - 1);
      if (c - u <= UNLEN + 1)
	strlcpy (user, u + 1, c - u);
    }
  if (domain[0])
    return;

  cygsid psid;
  DWORD ulen = UNLEN + 1;
  DWORD dlen = INTERNET_MAX_HOST_NAME_LENGTH + 1;
  SID_NAME_USE use;
  if (psid.getfrompw (pw))
    LookupAccountSid (NULL, psid, user, &ulen, domain, &dlen, &use);
}

extern "C" HANDLE
cygwin_logon_user (const struct passwd *pw, const char *password)
{
  if (!wincap.has_security ())
    {
      set_errno (ENOSYS);
      return INVALID_HANDLE_VALUE;
    }
  if (!pw)
    {
      set_errno (EINVAL);
      return INVALID_HANDLE_VALUE;
    }

  char nt_domain[INTERNET_MAX_HOST_NAME_LENGTH + 1];
  char nt_user[UNLEN + 1];
  HANDLE hToken;

  extract_nt_dom_user (pw, nt_domain, nt_user);
  debug_printf ("LogonUserA (%s, %s, %s, ...)", nt_user, nt_domain, password);
  /* CV 2005-06-08: LogonUser should run under the primary process token,
     otherwise it returns with ERROR_ACCESS_DENIED on W2K. Don't ask me why. */
  RevertToSelf ();
  if (!LogonUserA (nt_user, *nt_domain ? nt_domain : NULL, (char *) password,
		   LOGON32_LOGON_INTERACTIVE,
		   LOGON32_PROVIDER_DEFAULT,
		   &hToken))
    {
      __seterrno ();
      hToken = INVALID_HANDLE_VALUE;
    }
  else if (!SetHandleInformation (hToken,
				  HANDLE_FLAG_INHERIT,
				  HANDLE_FLAG_INHERIT))
    {
      __seterrno ();
      CloseHandle (hToken);
      hToken = INVALID_HANDLE_VALUE;
    }
  cygheap->user.reimpersonate ();
  debug_printf ("%d = logon_user(%s,...)", hToken, pw->pw_name);
  return hToken;
}

static void
str2lsa (LSA_STRING &tgt, const char *srcstr)
{
  tgt.Length = strlen (srcstr);
  tgt.MaximumLength = tgt.Length + 1;
  tgt.Buffer = (PCHAR) srcstr;
}

static void
str2buf2lsa (LSA_STRING &tgt, char *buf, const char *srcstr)
{
  tgt.Length = strlen (srcstr);
  tgt.MaximumLength = tgt.Length + 1;
  tgt.Buffer = (PCHAR) buf;
  memcpy (buf, srcstr, tgt.MaximumLength);
}

/* The dimension of buf is assumed to be at least strlen(srcstr) + 1,
   The result will be shorter if the input has multibyte chars */
void
str2buf2uni (UNICODE_STRING &tgt, WCHAR *buf, const char *srcstr)
{
  tgt.Buffer = (PWCHAR) buf;
  tgt.MaximumLength = (strlen (srcstr) + 1) * sizeof (WCHAR);
  tgt.Length = sys_mbstowcs (buf, srcstr, tgt.MaximumLength / sizeof (WCHAR))
	       * sizeof (WCHAR);
  if (tgt.Length)
    tgt.Length -= sizeof (WCHAR);
}

void
str2uni_cat (UNICODE_STRING &tgt, const char *srcstr)
{
  int len = sys_mbstowcs (tgt.Buffer + tgt.Length / sizeof (WCHAR), srcstr,
			  (tgt.MaximumLength - tgt.Length) / sizeof (WCHAR));
  if (len)
    tgt.Length += (len - 1) * sizeof (WCHAR);
  else
    tgt.Length = tgt.MaximumLength = 0;
}

#if 0				/* unused */
static void
lsa2wchar (WCHAR *tgt, LSA_UNICODE_STRING &src, int size)
{
  size = (size - 1) * sizeof (WCHAR);
  if (src.Length < size)
    size = src.Length;
  memcpy (tgt, src.Buffer, size);
  size >>= 1;
  tgt[size] = 0;
}
#endif

static void
lsa2str (char *tgt, LSA_UNICODE_STRING &src, int size)
{
  if (src.Length / 2 < size)
    size = src.Length / 2;
  sys_wcstombs (tgt, src.Buffer, size);
  tgt[size] = 0;
}

static LSA_HANDLE
open_local_policy ()
{
  LSA_OBJECT_ATTRIBUTES oa = { 0, 0, 0, 0, 0, 0 };
  LSA_HANDLE lsa = INVALID_HANDLE_VALUE;

  NTSTATUS ret = LsaOpenPolicy (NULL, &oa, POLICY_EXECUTE, &lsa);
  if (ret != STATUS_SUCCESS)
    __seterrno_from_win_error (LsaNtStatusToWinError (ret));
  return lsa;
}

static void
close_local_policy (LSA_HANDLE &lsa)
{
  if (lsa != INVALID_HANDLE_VALUE)
    LsaClose (lsa);
  lsa = INVALID_HANDLE_VALUE;
}

#if 0 /* unused */
static BOOL
get_lsa_srv_inf (LSA_HANDLE lsa, char *logonserver, char *domain)
{
  NET_API_STATUS ret;
  WCHAR *buf;
  char name[INTERNET_MAX_HOST_NAME_LENGTH + 1];
  WCHAR account[INTERNET_MAX_HOST_NAME_LENGTH + 1];
  WCHAR primary[INTERNET_MAX_HOST_NAME_LENGTH + 1];
  PPOLICY_ACCOUNT_DOMAIN_INFO adi;
  PPOLICY_PRIMARY_DOMAIN_INFO pdi;

  if ((ret = LsaQueryInformationPolicy (lsa, PolicyAccountDomainInformation,
					(PVOID *) &adi)) != STATUS_SUCCESS)
    {
      __seterrno_from_win_error (LsaNtStatusToWinError (ret));
      return FALSE;
    }
  lsa2wchar (account, adi->DomainName, INTERNET_MAX_HOST_NAME_LENGTH + 1);
  LsaFreeMemory (adi);
  if ((ret = LsaQueryInformationPolicy (lsa, PolicyPrimaryDomainInformation,
					(PVOID *) &pdi)) != STATUS_SUCCESS)
    {
      __seterrno_from_win_error (LsaNtStatusToWinError (ret));
      return FALSE;
    }
  lsa2wchar (primary, pdi->Name, INTERNET_MAX_HOST_NAME_LENGTH + 1);
  LsaFreeMemory (pdi);
  /* If the SID given in the primary domain info is NULL, the machine is
     not member of a domain.  The name in the primary domain info is the
     name of the workgroup then. */
  if (pdi->Sid &&
      (ret =
       NetGetDCName (NULL, primary, (LPBYTE *) &buf)) == STATUS_SUCCESS)
    {
      sys_wcstombs (name, buf, INTERNET_MAX_HOST_NAME_LENGTH + 1);
      strcpy (logonserver, name);
      if (domain)
	sys_wcstombs (domain, primary, INTERNET_MAX_HOST_NAME_LENGTH + 1);
    }
  else
    {
      sys_wcstombs (name, account, INTERNET_MAX_HOST_NAME_LENGTH + 1);
      strcpy (logonserver, "\\\\");
      strcat (logonserver, name);
      if (domain)
	sys_wcstombs (domain, account, INTERNET_MAX_HOST_NAME_LENGTH + 1);
    }
  if (ret == STATUS_SUCCESS)
    NetApiBufferFree (buf);
  return TRUE;
}
#endif

bool
get_logon_server (const char *domain, char *server, WCHAR *wserver)
{
  WCHAR wdomain[INTERNET_MAX_HOST_NAME_LENGTH + 1];
  NET_API_STATUS ret;
  WCHAR *buf;
  DWORD size = INTERNET_MAX_HOST_NAME_LENGTH + 1;

  /* Empty domain is interpreted as local system */
  if ((GetComputerName (server + 2, &size)) &&
      (strcasematch (domain, server + 2) || !domain[0]))
    {
      server[0] = server[1] = '\\';
      if (wserver)
	sys_mbstowcs (wserver, server, INTERNET_MAX_HOST_NAME_LENGTH + 1);
      return true;
    }

  /* Try to get the primary domain controller for the domain */
  sys_mbstowcs (wdomain, domain, INTERNET_MAX_HOST_NAME_LENGTH + 1);
  if ((ret = NetGetDCName (NULL, wdomain, (LPBYTE *) &buf)) == STATUS_SUCCESS)
    {
      sys_wcstombs (server, buf, INTERNET_MAX_HOST_NAME_LENGTH + 1);
      if (wserver)
	for (WCHAR *ptr1 = buf; (*wserver++ = *ptr1++);)
	  ;
      NetApiBufferFree (buf);
      return true;
    }
  __seterrno_from_win_error (ret);
  return false;
}

static bool
get_user_groups (WCHAR *wlogonserver, cygsidlist &grp_list, char *user,
		 char *domain)
{
  char dgroup[INTERNET_MAX_HOST_NAME_LENGTH + GNLEN + 2];
  WCHAR wuser[UNLEN + 1];
  sys_mbstowcs (wuser, user, UNLEN + 1);
  LPGROUP_USERS_INFO_0 buf;
  DWORD cnt, tot, len;
  NET_API_STATUS ret;

  /* Look only on logonserver */
  ret = NetUserGetGroups (wlogonserver, wuser, 0, (LPBYTE *) &buf,
			  MAX_PREFERRED_LENGTH, &cnt, &tot);
  if (ret)
    {
      __seterrno_from_win_error (ret);
      /* It's no error when the user name can't be found. */
      return ret == NERR_UserNotFound;
    }

  len = strlen (domain);
  strcpy (dgroup, domain);
  dgroup[len++] = '\\';

  for (DWORD i = 0; i < cnt; ++i)
    {
      cygsid gsid;
      DWORD glen = MAX_SID_LEN;
      char domain[INTERNET_MAX_HOST_NAME_LENGTH + 1];
      DWORD dlen = sizeof (domain);
      SID_NAME_USE use = SidTypeInvalid;

      sys_wcstombs (dgroup + len, buf[i].grui0_name, GNLEN + 1);
      if (!LookupAccountName (NULL, dgroup, gsid, &glen, domain, &dlen, &use))
	debug_printf ("LookupAccountName(%s), %E", dgroup);
      else if (legal_sid_type (use))
	grp_list += gsid;
      else
	debug_printf ("Global group %s invalid. Domain: %s Use: %d",
		      dgroup, domain, use);
    }

  NetApiBufferFree (buf);
  return true;
}

static bool
is_group_member (WCHAR *wgroup, PSID pusersid, cygsidlist &grp_list)
{
  LPLOCALGROUP_MEMBERS_INFO_0 buf;
  DWORD cnt, tot;
  NET_API_STATUS ret;

  /* Members can be users or global groups */
  ret = NetLocalGroupGetMembers (NULL, wgroup, 0, (LPBYTE *) &buf,
				 MAX_PREFERRED_LENGTH, &cnt, &tot, NULL);
  if (ret)
    return false;

  bool retval = true;
  for (DWORD bidx = 0; bidx < cnt; ++bidx)
    if (EqualSid (pusersid, buf[bidx].lgrmi0_sid))
      goto done;
    else
      for (int glidx = 0; glidx < grp_list.count; ++glidx)
	if (EqualSid (grp_list.sids[glidx], buf[bidx].lgrmi0_sid))
	  goto done;

  retval = false;
 done:
  NetApiBufferFree (buf);
  return retval;
}

static bool
get_user_local_groups (cygsidlist &grp_list, PSID pusersid)
{
  LPLOCALGROUP_INFO_0 buf;
  DWORD cnt, tot;
  NET_API_STATUS ret;

  ret = NetLocalGroupEnum (NULL, 0, (LPBYTE *) &buf,
			   MAX_PREFERRED_LENGTH, &cnt, &tot, NULL);
  if (ret)
    {
      __seterrno_from_win_error (ret);
      return false;
    }

  char bgroup[INTERNET_MAX_HOST_NAME_LENGTH + GNLEN + 2];
  char lgroup[INTERNET_MAX_HOST_NAME_LENGTH + GNLEN + 2];
  DWORD blen, llen;
  SID_NAME_USE use;

  blen = llen = INTERNET_MAX_HOST_NAME_LENGTH + 1;
  if (!LookupAccountSid (NULL, well_known_admins_sid, lgroup, &llen, bgroup, &blen, &use)
      || !GetComputerNameA (lgroup, &(llen = INTERNET_MAX_HOST_NAME_LENGTH + 1)))
    {
      __seterrno ();
      return false;
    }
  bgroup[blen++] = lgroup[llen++] = '\\';

  for (DWORD i = 0; i < cnt; ++i)
    if (is_group_member (buf[i].lgrpi0_name, pusersid, grp_list))
      {
	cygsid gsid;
	DWORD glen = MAX_SID_LEN;
	char domain[INTERNET_MAX_HOST_NAME_LENGTH + 1];
	DWORD dlen = sizeof (domain);

	use = SidTypeInvalid;
	sys_wcstombs (bgroup + blen, buf[i].lgrpi0_name, GNLEN + 1);
	if (!LookupAccountName (NULL, bgroup, gsid, &glen, domain, &dlen, &use))
	  {
	    if (GetLastError () != ERROR_NONE_MAPPED)
	      debug_printf ("LookupAccountName(%s), %E", bgroup);
	    strcpy (lgroup + llen, bgroup + blen);
	    if (!LookupAccountName (NULL, lgroup, gsid, &glen,
				    domain, &dlen, &use))
	      debug_printf ("LookupAccountName(%s), %E", lgroup);
	  }
	if (!legal_sid_type (use))
	  debug_printf ("Rejecting local %s. use: %d", bgroup + blen, use);
	else if (!grp_list.contains (gsid))
	  grp_list += gsid;
      }
  NetApiBufferFree (buf);
  return true;
}

static bool
sid_in_token_groups (PTOKEN_GROUPS grps, cygpsid sid)
{
  if (!grps)
    return false;
  for (DWORD i = 0; i < grps->GroupCount; ++i)
    if (sid == grps->Groups[i].Sid)
      return true;
  return false;
}

#if 0				/* Unused */
static BOOL
get_user_primary_group (WCHAR *wlogonserver, const char *user,
			PSID pusersid, cygsid &pgrpsid)
{
  LPUSER_INFO_3 buf;
  WCHAR wuser[UNLEN + 1];
  NET_API_STATUS ret;
  BOOL retval = FALSE;
  UCHAR count = 0;

  if (well_known_system_sid == pusersid)
    {
      pgrpsid = well_known_system_sid;
      return TRUE;
    }

  sys_mbstowcs (wuser, user, UNLEN + 1);
  ret = NetUserGetInfo (wlogonserver, wuser, 3, (LPBYTE *) &buf);
  if (ret)
    {
      __seterrno_from_win_error (ret);
      return FALSE;
    }

  pgrpsid = pusersid;
  if (IsValidSid (pgrpsid)
      && (count = *GetSidSubAuthorityCount (pgrpsid)) > 1)
    {
      *GetSidSubAuthority (pgrpsid, count - 1) = buf->usri3_primary_group_id;
      retval = TRUE;
    }
  NetApiBufferFree (buf);
  return retval;
}
#endif

static void
get_unix_group_sidlist (struct passwd *pw, cygsidlist &grp_list)
{
  struct __group32 *gr;
  cygsid gsid;

  for (int gidx = 0; (gr = internal_getgrent (gidx)); ++gidx)
    {
      if (gr->gr_gid == (__gid32_t) pw->pw_gid)
	goto found;
      else if (gr->gr_mem)
	for (int gi = 0; gr->gr_mem[gi]; ++gi)
	  if (strcasematch (pw->pw_name, gr->gr_mem[gi]))
	    goto found;
      continue;
    found:
      if (gsid.getfromgr (gr) && !grp_list.contains (gsid))
	grp_list += gsid;

    }
}

static void
get_token_group_sidlist (cygsidlist &grp_list, PTOKEN_GROUPS my_grps,
			 LUID auth_luid, int &auth_pos)
{
  auth_pos = -1;
  if (my_grps)
    {
      if (sid_in_token_groups (my_grps, well_known_local_sid))
	grp_list += well_known_local_sid;
      if (sid_in_token_groups (my_grps, well_known_dialup_sid))
	grp_list += well_known_dialup_sid;
      if (sid_in_token_groups (my_grps, well_known_network_sid))
	grp_list += well_known_network_sid;
      if (sid_in_token_groups (my_grps, well_known_batch_sid))
	grp_list += well_known_batch_sid;
      if (sid_in_token_groups (my_grps, well_known_interactive_sid))
	grp_list += well_known_interactive_sid;
      if (sid_in_token_groups (my_grps, well_known_service_sid))
	grp_list += well_known_service_sid;
    }
  else
    {
      grp_list += well_known_local_sid;
      grp_list += well_known_interactive_sid;
    }
  if (get_ll (auth_luid) != 999LL) /* != SYSTEM_LUID */
    {
      char buf[64];
      __small_sprintf (buf, "S-1-5-5-%u-%u", auth_luid.HighPart,
		       auth_luid.LowPart);
      grp_list += buf;
      auth_pos = grp_list.count - 1;
    }
}

bool
get_server_groups (cygsidlist &grp_list, PSID usersid, struct passwd *pw)
{
  char user[UNLEN + 1];
  char domain[INTERNET_MAX_HOST_NAME_LENGTH + 1];
  WCHAR wserver[INTERNET_MAX_HOST_NAME_LENGTH + 3];
  char server[INTERNET_MAX_HOST_NAME_LENGTH + 3];

  if (well_known_system_sid == usersid)
    {
      grp_list += well_known_admins_sid;
      get_unix_group_sidlist (pw, grp_list);
      return true;
    }

  grp_list += well_known_world_sid;
  grp_list += well_known_authenticated_users_sid;
  extract_nt_dom_user (pw, domain, user);
  if (get_logon_server (domain, server, wserver))
    get_user_groups (wserver, grp_list, user, domain);
  get_unix_group_sidlist (pw, grp_list);
  return get_user_local_groups (grp_list, usersid);
}

static bool
get_initgroups_sidlist (cygsidlist &grp_list,
			PSID usersid, PSID pgrpsid, struct passwd *pw,
			PTOKEN_GROUPS my_grps, LUID auth_luid, int &auth_pos,
			bool &special_pgrp)
{
  grp_list += well_known_world_sid;
  grp_list += well_known_authenticated_users_sid;
  if (well_known_system_sid == usersid)
    auth_pos = -1;
   else
     get_token_group_sidlist (grp_list, my_grps, auth_luid, auth_pos);
  if (!get_server_groups (grp_list, usersid, pw))
    return false;

  /* special_pgrp true if pgrpsid is not in normal groups */
  if ((special_pgrp = !grp_list.contains (pgrpsid)))
    grp_list += pgrpsid;
  return true;
}

static void
get_setgroups_sidlist (cygsidlist &tmp_list, PTOKEN_GROUPS my_grps,
		       user_groups &groups, LUID auth_luid, int &auth_pos)
{
  PSID pgpsid = groups.pgsid;
  tmp_list += well_known_world_sid;
  tmp_list += well_known_authenticated_users_sid;
  get_token_group_sidlist (tmp_list, my_grps, auth_luid, auth_pos);
  for (int gidx = 0; gidx < groups.sgsids.count; gidx++)
    tmp_list += groups.sgsids.sids[gidx];
  if (!groups.sgsids.contains (pgpsid))
    tmp_list += pgpsid;
}

static const cygpriv_idx sys_privs[] = {
  SE_TCB_PRIV,
  SE_ASSIGNPRIMARYTOKEN_PRIV,
  SE_CREATE_TOKEN_PRIV,
  SE_CHANGE_NOTIFY_PRIV,
  SE_SECURITY_PRIV,
  SE_BACKUP_PRIV,
  SE_RESTORE_PRIV,
  SE_SYSTEMTIME_PRIV,
  SE_SHUTDOWN_PRIV,
  SE_REMOTE_SHUTDOWN_PRIV,
  SE_TAKE_OWNERSHIP_PRIV,
  SE_DEBUG_PRIV,
  SE_SYSTEM_ENVIRONMENT_PRIV,
  SE_SYSTEM_PROFILE_PRIV,
  SE_PROF_SINGLE_PROCESS_PRIV,
  SE_INC_BASE_PRIORITY_PRIV,
  SE_LOAD_DRIVER_PRIV,
  SE_CREATE_PAGEFILE_PRIV,
  SE_INCREASE_QUOTA_PRIV,
  SE_LOCK_MEMORY_PRIV,
  SE_CREATE_PERMANENT_PRIV,
  SE_AUDIT_PRIV,
  SE_UNDOCK_PRIV,
  SE_MANAGE_VOLUME_PRIV,
  SE_IMPERSONATE_PRIV,
  SE_CREATE_GLOBAL_PRIV
};

#define SYSTEM_PRIVILEGES_COUNT (sizeof sys_privs / sizeof *sys_privs)

PTOKEN_PRIVILEGES
get_system_priv_list (cygsidlist &grp_list)
{
  const LUID *priv;
  PTOKEN_PRIVILEGES privs = (PTOKEN_PRIVILEGES)
    malloc (sizeof (ULONG)
	    + SYSTEM_PRIVILEGES_COUNT * sizeof (LUID_AND_ATTRIBUTES));
  if (!privs)
    {
      debug_printf ("malloc (system_privs) failed.");
      return NULL;
    }
  privs->PrivilegeCount = 0;

  for (DWORD i = 0; i < SYSTEM_PRIVILEGES_COUNT; ++i)
    if ((priv = privilege_luid (sys_privs[i])))
      {
	privs->Privileges[privs->PrivilegeCount].Luid = *priv;
	privs->Privileges[privs->PrivilegeCount].Attributes =
	  SE_PRIVILEGE_ENABLED | SE_PRIVILEGE_ENABLED_BY_DEFAULT;
	++privs->PrivilegeCount;
      }
  return privs;
}

PTOKEN_PRIVILEGES
get_priv_list (LSA_HANDLE lsa, cygsid &usersid, cygsidlist &grp_list)
{
  PLSA_UNICODE_STRING privstrs;
  ULONG cnt;
  PTOKEN_PRIVILEGES privs = NULL;
  NTSTATUS ret;
  char buf[INTERNET_MAX_HOST_NAME_LENGTH + 1];

  if (usersid == well_known_system_sid)
    return get_system_priv_list (grp_list);

  for (int grp = -1; grp < grp_list.count; ++grp)
    {
      if (grp == -1)
	{
	  if ((ret = LsaEnumerateAccountRights (lsa, usersid, &privstrs,
						&cnt)) != STATUS_SUCCESS)
	    continue;
	}
      else if ((ret = LsaEnumerateAccountRights (lsa, grp_list.sids[grp],
						 &privstrs, &cnt))
	       != STATUS_SUCCESS)
	continue;
      for (ULONG i = 0; i < cnt; ++i)
	{
	  const LUID *priv;
	  PTOKEN_PRIVILEGES tmp;
	  DWORD tmp_count;

	  lsa2str (buf, privstrs[i], sizeof (buf) - 1);
	  if (!(priv = privilege_luid_by_name (buf)))
	    continue;

	  if (privs)
	    {
	      DWORD pcnt = privs->PrivilegeCount;
	      LUID_AND_ATTRIBUTES *p = privs->Privileges;
	      for (; pcnt > 0; --pcnt, ++p)
		if (priv->HighPart == p->Luid.HighPart
		    && priv->LowPart == p->Luid.LowPart)
		  goto next_account_right;
	    }

	  tmp_count = privs ? privs->PrivilegeCount : 0;
	  tmp = (PTOKEN_PRIVILEGES)
	    realloc (privs, sizeof (ULONG) +
		     (tmp_count + 1) * sizeof (LUID_AND_ATTRIBUTES));
	  if (!tmp)
	    {
	      if (privs)
		free (privs);
	      LsaFreeMemory (privstrs);
	      debug_printf ("realloc (privs) failed.");
	      return NULL;
	    }
	  tmp->PrivilegeCount = tmp_count;
	  privs = tmp;
	  privs->Privileges[privs->PrivilegeCount].Luid = *priv;
	  privs->Privileges[privs->PrivilegeCount].Attributes =
	    SE_PRIVILEGE_ENABLED | SE_PRIVILEGE_ENABLED_BY_DEFAULT;
	  ++privs->PrivilegeCount;

	next_account_right:
	  ;
	}
      LsaFreeMemory (privstrs);
    }
  return privs;
}

/* Accept a token if
   - the requested usersid matches the TokenUser and
   - if setgroups has been called:
	the token groups that are listed in /etc/group match the union of
	the requested primary and supplementary groups in gsids.
   - else the (unknown) implicitly requested supplementary groups and those
	in the token are the groups associated with the usersid. We assume
	they match and verify only the primary groups.
	The requested primary group must appear in the token.
	The primary group in the token is a group associated with the usersid,
	except if the token is internal and the group is in the token SD
	(see create_token). In that latter case that group must match the
	requested primary group.  */
bool
verify_token (HANDLE token, cygsid &usersid, user_groups &groups, bool *pintern)
{
  DWORD size;
  bool intern = false;

  if (pintern)
    {
      TOKEN_SOURCE ts;
      if (!GetTokenInformation (token, TokenSource,
				&ts, sizeof ts, &size))
	debug_printf ("GetTokenInformation(), %E");
      else
	*pintern = intern = !memcmp (ts.SourceName, "Cygwin.1", 8);
    }
  /* Verify usersid */
  cygsid tok_usersid = NO_SID;
  if (!GetTokenInformation (token, TokenUser,
			    &tok_usersid, sizeof tok_usersid, &size))
    debug_printf ("GetTokenInformation(), %E");
  if (usersid != tok_usersid)
    return false;

  /* For an internal token, if setgroups was not called and if the sd group
     is not well_known_null_sid, it must match pgrpsid */
  if (intern && !groups.issetgroups ())
    {
      const DWORD sd_buf_siz = MAX_SID_LEN + sizeof (SECURITY_DESCRIPTOR);
      PSECURITY_DESCRIPTOR sd_buf = (PSECURITY_DESCRIPTOR) alloca (sd_buf_siz);
      cygpsid gsid (NO_SID);
      if (!GetKernelObjectSecurity (token, GROUP_SECURITY_INFORMATION,
				    sd_buf, sd_buf_siz, &size))
	debug_printf ("GetKernelObjectSecurity(), %E");
      else if (!GetSecurityDescriptorGroup (sd_buf, (PSID *) &gsid,
					    (BOOL *) &size))
	debug_printf ("GetSecurityDescriptorGroup(), %E");
      if (well_known_null_sid != gsid)
	return gsid == groups.pgsid;
    }

  PTOKEN_GROUPS my_grps;
  bool sawpg = false, ret = false;

  if (!GetTokenInformation (token, TokenGroups, NULL, 0, &size) &&
      GetLastError () != ERROR_INSUFFICIENT_BUFFER)
    debug_printf ("GetTokenInformation(token, TokenGroups), %E");
  else if (!(my_grps = (PTOKEN_GROUPS) alloca (size)))
    debug_printf ("alloca (my_grps) failed.");
  else if (!GetTokenInformation (token, TokenGroups, my_grps, size, &size))
    debug_printf ("GetTokenInformation(my_token, TokenGroups), %E");
  else
    {
      if (groups.issetgroups ()) /* setgroups was called */
	{
	  cygsid gsid;
	  struct __group32 *gr;
	  bool saw[groups.sgsids.count];
	  memset (saw, 0, sizeof(saw));

	  /* token groups found in /etc/group match the user.gsids ? */
	  for (int gidx = 0; (gr = internal_getgrent (gidx)); ++gidx)
	    if (gsid.getfromgr (gr) && sid_in_token_groups (my_grps, gsid))
	      {
		int pos = groups.sgsids.position (gsid);
		if (pos >= 0)
		  saw[pos] = true;
		else if (groups.pgsid == gsid)
		  sawpg = true;
		else if (gsid != well_known_world_sid
			 && gsid != usersid)
		  goto done;
	      }
	  /* user.sgsids groups must be in the token */
	  for (int gidx = 0; gidx < groups.sgsids.count; gidx++)
	    if (!saw[gidx] && !sid_in_token_groups (my_grps, groups.sgsids.sids[gidx]))
	      goto done;
	}
      /* The primary group must be in the token */
      ret = sawpg
	|| sid_in_token_groups (my_grps, groups.pgsid)
	|| groups.pgsid == usersid;
    }
done:
  return ret;
}

HANDLE
create_token (cygsid &usersid, user_groups &new_groups, struct passwd *pw)
{
  NTSTATUS ret;
  LSA_HANDLE lsa = INVALID_HANDLE_VALUE;

  cygsidlist tmp_gsids (cygsidlist_auto, 12);

  SECURITY_QUALITY_OF_SERVICE sqos =
    { sizeof sqos, SecurityImpersonation, SECURITY_STATIC_TRACKING, FALSE };
  OBJECT_ATTRIBUTES oa = { sizeof oa, 0, 0, 0, 0, &sqos };
  bool special_pgrp = false;
  LUID auth_luid = SYSTEM_LUID;
  LARGE_INTEGER exp = { QuadPart:INT64_MAX };

  TOKEN_USER user;
  PTOKEN_GROUPS new_tok_gsids = NULL;
  PTOKEN_PRIVILEGES privs = NULL;
  TOKEN_OWNER owner;
  TOKEN_PRIMARY_GROUP pgrp;
  TOKEN_DEFAULT_DACL dacl = {};
  TOKEN_SOURCE source;
  TOKEN_STATISTICS stats;
  memcpy (source.SourceName, "Cygwin.1", 8);
  source.SourceIdentifier.HighPart = 0;
  source.SourceIdentifier.LowPart = 0x0101;

  HANDLE token = INVALID_HANDLE_VALUE;
  HANDLE primary_token = INVALID_HANDLE_VALUE;

  PTOKEN_GROUPS my_tok_gsids = NULL;
  DWORD size;

  /* SE_CREATE_TOKEN_NAME privilege needed to call NtCreateToken. */
  push_self_privilege (SE_CREATE_TOKEN_PRIV, true);

  /* Open policy object. */
  if ((lsa = open_local_policy ()) == INVALID_HANDLE_VALUE)
    goto out;

  /* User, owner, primary group. */
  user.User.Sid = usersid;
  user.User.Attributes = 0;
  owner.Owner = usersid;

  /* Retrieve authentication id and group list from own process. */
  if (hProcToken)
    {
      /* Switching user context to SYSTEM doesn't inherit the authentication
	 id of the user account running current process. */
      if (usersid != well_known_system_sid)
	if (!GetTokenInformation (hProcToken, TokenStatistics,
				  &stats, sizeof stats, &size))
	  debug_printf
	    ("GetTokenInformation(hProcToken, TokenStatistics), %E");
	else
	  auth_luid = stats.AuthenticationId;

      /* Retrieving current processes group list to be able to inherit
	 some important well known group sids. */
      if (!GetTokenInformation (hProcToken, TokenGroups, NULL, 0, &size) &&
	  GetLastError () != ERROR_INSUFFICIENT_BUFFER)
	debug_printf ("GetTokenInformation(hProcToken, TokenGroups), %E");
      else if (!(my_tok_gsids = (PTOKEN_GROUPS) malloc (size)))
	debug_printf ("malloc (my_tok_gsids) failed.");
      else if (!GetTokenInformation (hProcToken, TokenGroups, my_tok_gsids,
				     size, &size))
	{
	  debug_printf ("GetTokenInformation(hProcToken, TokenGroups), %E");
	  free (my_tok_gsids);
	  my_tok_gsids = NULL;
	}
    }

  /* Create list of groups, the user is member in. */
  int auth_pos;
  if (new_groups.issetgroups ())
    get_setgroups_sidlist (tmp_gsids, my_tok_gsids, new_groups, auth_luid,
			   auth_pos);
  else if (!get_initgroups_sidlist (tmp_gsids, usersid, new_groups.pgsid, pw,
				    my_tok_gsids, auth_luid, auth_pos,
				    special_pgrp))
    goto out;

  /* Primary group. */
  pgrp.PrimaryGroup = new_groups.pgsid;

  /* Create a TOKEN_GROUPS list from the above retrieved list of sids. */
  char grps_buf[sizeof (ULONG) + tmp_gsids.count * sizeof (SID_AND_ATTRIBUTES)];
  new_tok_gsids = (PTOKEN_GROUPS) grps_buf;
  new_tok_gsids->GroupCount = tmp_gsids.count;
  for (DWORD i = 0; i < new_tok_gsids->GroupCount; ++i)
    {
      new_tok_gsids->Groups[i].Sid = tmp_gsids.sids[i];
      new_tok_gsids->Groups[i].Attributes = SE_GROUP_MANDATORY |
	SE_GROUP_ENABLED_BY_DEFAULT | SE_GROUP_ENABLED;
    }
  if (auth_pos >= 0)
    new_tok_gsids->Groups[auth_pos].Attributes |= SE_GROUP_LOGON_ID;

  /* Retrieve list of privileges of that user. */
  if (!(privs = get_priv_list (lsa, usersid, tmp_gsids)))
    goto out;

  /* Let's be heroic... */
  ret = NtCreateToken (&token, TOKEN_ALL_ACCESS, &oa, TokenImpersonation,
		       &auth_luid, &exp, &user, new_tok_gsids, privs, &owner,
		       &pgrp, &dacl, &source);
  if (ret)
    __seterrno_from_nt_status (ret);
  else if (GetLastError () == ERROR_PROC_NOT_FOUND)
    {
      __seterrno ();
      debug_printf ("Loading NtCreateToken failed.");
    }
  else
    {
      /* Convert to primary token. */
      if (!DuplicateTokenEx (token, MAXIMUM_ALLOWED, &sec_none,
			     SecurityImpersonation, TokenPrimary,
			     &primary_token))
	{
	  __seterrno ();
	  debug_printf ("DuplicateTokenEx %E");
	}
    }

out:
  pop_self_privilege ();
  if (token != INVALID_HANDLE_VALUE)
    CloseHandle (token);
  if (privs)
    free (privs);
  if (my_tok_gsids)
    free (my_tok_gsids);
  close_local_policy (lsa);

  debug_printf ("%d = create_token ()", primary_token);
  return primary_token;
}

int subauth_id = 255;

HANDLE
subauth (struct passwd *pw)
{
  LSA_STRING name;
  HANDLE lsa_hdl;
  LSA_OPERATIONAL_MODE sec_mode;
  NTSTATUS ret, ret2;
  ULONG package_id, size;
  struct {
    LSA_STRING str;
    CHAR buf[16];
  } origin;
  struct {
    MSV1_0_LM20_LOGON auth;
    WCHAR dombuf[INTERNET_MAX_HOST_NAME_LENGTH + 1];
    WCHAR usrbuf[UNLEN + 1];
    WCHAR wkstbuf[1];
    CHAR authinf1[1];
    CHAR authinf2[1];
  } subbuf;
  TOKEN_SOURCE ts;
  PMSV1_0_LM20_LOGON_PROFILE profile;
  LUID luid;
  QUOTA_LIMITS quota;
  char nt_domain[INTERNET_MAX_HOST_NAME_LENGTH + 1];
  char nt_user[UNLEN + 1];
  HANDLE user_token = INVALID_HANDLE_VALUE;
  HANDLE primary_token = INVALID_HANDLE_VALUE;

  push_self_privilege (SE_TCB_PRIV, true);

  /* Register as logon process. */
  str2lsa (name, "Cygwin");
  SetLastError (0);
  ret = LsaRegisterLogonProcess (&name, &lsa_hdl, &sec_mode);
  if (ret != STATUS_SUCCESS)
    {
      debug_printf ("LsaRegisterLogonProcess: %d", ret);
      __seterrno_from_win_error (LsaNtStatusToWinError (ret));
      goto out;
    }
  else if (GetLastError () == ERROR_PROC_NOT_FOUND)
    {
      debug_printf ("Couldn't load Secur32.dll");
      goto out;
    }
  /* Get handle to MSV1_0 package. */
  str2lsa (name, MSV1_0_PACKAGE_NAME);
  ret = LsaLookupAuthenticationPackage (lsa_hdl, &name, &package_id);
  if (ret != STATUS_SUCCESS)
    {
      debug_printf ("LsaLookupAuthenticationPackage: %d", ret);
      __seterrno_from_win_error (LsaNtStatusToWinError (ret));
      LsaDeregisterLogonProcess (lsa_hdl);
      goto out;
    }
  /* Create origin. */
  str2buf2lsa (origin.str, origin.buf, "Cygwin");
  /* Create token source. */
  memcpy (ts.SourceName, "Cygwin.1", 8);
  ts.SourceIdentifier.HighPart = 0;
  ts.SourceIdentifier.LowPart = 0x0100;
  /* Get user information. */
  extract_nt_dom_user (pw, nt_domain, nt_user);
  /* Fill subauth with values. */
  subbuf.auth.MessageType = MsV1_0NetworkLogon;
  str2buf2uni (subbuf.auth.LogonDomainName, subbuf.dombuf, nt_domain);
  str2buf2uni (subbuf.auth.UserName, subbuf.usrbuf, nt_user);
  str2buf2uni (subbuf.auth.Workstation, subbuf.wkstbuf, "");
  memcpy (subbuf.auth.ChallengeToClient, "12345678", MSV1_0_CHALLENGE_LENGTH);
  str2buf2lsa (subbuf.auth.CaseSensitiveChallengeResponse, subbuf.authinf1, "");
  str2buf2lsa (subbuf.auth.CaseInsensitiveChallengeResponse,subbuf.authinf2,"");
  subbuf.auth.ParameterControl = 0 | (subauth_id << 24);
  /* Try to logon... */
  ret = LsaLogonUser (lsa_hdl, (PLSA_STRING) &origin, Network,
		      package_id, &subbuf, sizeof subbuf,
		      NULL, &ts, (PVOID *) &profile, &size,
		      &luid, &user_token, &quota, &ret2);
  if (ret != STATUS_SUCCESS)
    {
      debug_printf ("LsaLogonUser: %d", ret);
      __seterrno_from_win_error (LsaNtStatusToWinError (ret));
      LsaDeregisterLogonProcess (lsa_hdl);
      goto out;
    }
  LsaFreeReturnBuffer (profile);
  /* Convert to primary token. */
  if (!DuplicateTokenEx (user_token, TOKEN_ALL_ACCESS, &sec_none,
			 SecurityImpersonation, TokenPrimary, &primary_token))
    __seterrno ();

out:
  pop_self_privilege ();
  if (user_token != INVALID_HANDLE_VALUE)
    CloseHandle (user_token);
  return primary_token;
}

/* read_sd reads a security descriptor from a file.
   In case of error, -1 is returned and errno is set.
   If sd_buf is too small, 0 is returned and sd_size
   is set to the needed buffer size.
   On success, 1 is returned.

   GetFileSecurity() is used instead of BackupRead()
   to avoid access denied errors if the caller has
   not the permission to open that file for read.

   Originally the function should return the size
   of the SD on success. Unfortunately NT returns
   0 in `len' on success, while W2K returns the
   correct size!

   2003-11-26: Now the function allocates the space needed by itself so
   it knows the real size and returns it in the security_descriptor object.
*/

LONG
read_sd (const char *file, security_descriptor &sd)
{

  DWORD len = 0;
  const char *pfile = file;
  char fbuf[CYG_MAX_PATH];
  if (current_codepage == oem_cp)
    {
      DWORD fname_len = min (sizeof (fbuf) - 1, strlen (file));
      bzero (fbuf, sizeof (fbuf));
      OemToCharBuff (file, fbuf, fname_len);
      pfile = fbuf;
    }

  if (!GetFileSecurity (pfile,
			OWNER_SECURITY_INFORMATION
			| GROUP_SECURITY_INFORMATION
			| DACL_SECURITY_INFORMATION,
			NULL, 0, &len)
      && GetLastError () != ERROR_INSUFFICIENT_BUFFER)
    {
      debug_printf ("file %s", file);
      __seterrno ();
      return -1;
    }
  debug_printf ("file %s: len %d", file, len);
  if (!sd.malloc (len))
    {
      set_errno (ENOMEM);
      return -1;
    }
  if (!GetFileSecurity (pfile,
			OWNER_SECURITY_INFORMATION
			| GROUP_SECURITY_INFORMATION
			| DACL_SECURITY_INFORMATION,
			sd, len, &len))
    {
      __seterrno ();
      return -1;
    }
  return sd.size ();
}

LONG
write_sd (HANDLE fh, const char *file, security_descriptor &sd)
{
  NTSTATUS ret = STATUS_SUCCESS;
  int retry = 0;
  int res = -1;
  for (; retry < 2; ++retry)
    {
      if (retry && (fh = CreateFile (file, WRITE_OWNER | WRITE_DAC,
				     FILE_SHARE_READ | FILE_SHARE_WRITE,
				     &sec_none_nih, OPEN_EXISTING,
				     FILE_ATTRIBUTE_NORMAL
				     | FILE_FLAG_BACKUP_SEMANTICS,
				     NULL)) == INVALID_HANDLE_VALUE)
	break;
      if (fh && (ret = NtSetSecurityObject (fh,
					    DACL_SECURITY_INFORMATION
					    | GROUP_SECURITY_INFORMATION
					    | OWNER_SECURITY_INFORMATION,
					    sd)) == STATUS_SUCCESS)
	break;
    }
  if (retry && fh != INVALID_HANDLE_VALUE)
    CloseHandle (fh);
  if (fh == INVALID_HANDLE_VALUE)	/* CreateFile failed */
    __seterrno ();
  else if (ret != STATUS_SUCCESS)	/* NtSetSecurityObject failed */
    __seterrno_from_nt_status (ret);
  else					/* Everything's fine. */
    res = 0;
  return res;
}

static void
get_attribute_from_acl (mode_t *attribute, PACL acl, PSID owner_sid,
			PSID group_sid, bool grp_member)
{
  ACCESS_ALLOWED_ACE *ace;
  int allow = 0;
  int deny = 0;
  int *flags, *anti;

  for (DWORD i = 0; i < acl->AceCount; ++i)
    {
      if (!GetAce (acl, i, (PVOID *) &ace))
	continue;
      if (ace->Header.AceFlags & INHERIT_ONLY)
	continue;
      switch (ace->Header.AceType)
	{
	case ACCESS_ALLOWED_ACE_TYPE:
	  flags = &allow;
	  anti = &deny;
	  break;
	case ACCESS_DENIED_ACE_TYPE:
	  flags = &deny;
	  anti = &allow;
	  break;
	default:
	  continue;
	}

      cygpsid ace_sid ((PSID) &ace->SidStart);
      if (ace_sid == well_known_world_sid)
	{
	  if (ace->Mask & FILE_READ_BITS)
	    *flags |= ((!(*anti & S_IROTH)) ? S_IROTH : 0)
		      | ((!(*anti & S_IRGRP)) ? S_IRGRP : 0)
		      | ((!(*anti & S_IRUSR)) ? S_IRUSR : 0);
	  if (ace->Mask & FILE_WRITE_BITS)
	    *flags |= ((!(*anti & S_IWOTH)) ? S_IWOTH : 0)
		      | ((!(*anti & S_IWGRP)) ? S_IWGRP : 0)
		      | ((!(*anti & S_IWUSR)) ? S_IWUSR : 0);
	  if (ace->Mask & FILE_EXEC_BITS)
	    *flags |= ((!(*anti & S_IXOTH)) ? S_IXOTH : 0)
		      | ((!(*anti & S_IXGRP)) ? S_IXGRP : 0)
		      | ((!(*anti & S_IXUSR)) ? S_IXUSR : 0);
	  if ((S_ISDIR (*attribute)) &&
	      (ace->Mask & (FILE_WRITE_DATA | FILE_EXECUTE | FILE_DELETE_CHILD))
	      == (FILE_WRITE_DATA | FILE_EXECUTE))
	    *flags |= S_ISVTX;
	}
      else if (ace_sid == well_known_null_sid)
	{
	  /* Read SUID, SGID and VTX bits from NULL ACE. */
	  if (ace->Mask & FILE_READ_DATA)
	    *flags |= S_ISVTX;
	  if (ace->Mask & FILE_WRITE_DATA)
	    *flags |= S_ISGID;
	  if (ace->Mask & FILE_APPEND_DATA)
	    *flags |= S_ISUID;
	}
      else if (ace_sid == owner_sid)
	{
	  if (ace->Mask & FILE_READ_BITS)
	    *flags |= ((!(*anti & S_IRUSR)) ? S_IRUSR : 0);
	  if (ace->Mask & FILE_WRITE_BITS)
	    *flags |= ((!(*anti & S_IWUSR)) ? S_IWUSR : 0);
	  if (ace->Mask & FILE_EXEC_BITS)
	    *flags |= ((!(*anti & S_IXUSR)) ? S_IXUSR : 0);
	}
      else if (ace_sid == group_sid)
	{
	  if (ace->Mask & FILE_READ_BITS)
	    *flags |= ((!(*anti & S_IRGRP)) ? S_IRGRP : 0)
		      | ((grp_member && !(*anti & S_IRUSR)) ? S_IRUSR : 0);
	  if (ace->Mask & FILE_WRITE_BITS)
	    *flags |= ((!(*anti & S_IWGRP)) ? S_IWGRP : 0)
		      | ((grp_member && !(*anti & S_IWUSR)) ? S_IWUSR : 0);
	  if (ace->Mask & FILE_EXEC_BITS)
	    *flags |= ((!(*anti & S_IXGRP)) ? S_IXGRP : 0)
		      | ((grp_member && !(*anti & S_IXUSR)) ? S_IXUSR : 0);
	}
    }
  *attribute &= ~(S_IRWXU | S_IRWXG | S_IRWXO | S_ISVTX | S_ISGID | S_ISUID);
  if (owner_sid && group_sid && EqualSid (owner_sid, group_sid)
      /* FIXME: temporary exception for /var/empty */
      && well_known_system_sid != group_sid)
    {
      allow &= ~(S_IRGRP | S_IWGRP | S_IXGRP);
      allow |= (((allow & S_IRUSR) ? S_IRGRP : 0)
		| ((allow & S_IWUSR) ? S_IWGRP : 0)
		| ((allow & S_IXUSR) ? S_IXGRP : 0));
    }
  *attribute |= allow;
  return;
}

static void
get_info_from_sd (PSECURITY_DESCRIPTOR psd, mode_t *attribute,
		  __uid32_t *uidret, __gid32_t *gidret)
{
  if (!psd)
    {
      /* If reading the security descriptor failed, treat the object
	 as unreadable. */
      if (attribute)
	*attribute &= ~(S_IRWXU | S_IRWXG | S_IRWXO);
      if (uidret)
	*uidret = ILLEGAL_UID;
      if (gidret)
	*gidret = ILLEGAL_GID;
      return;
    }

  cygpsid owner_sid;
  cygpsid group_sid;
  BOOL dummy;

  if (!GetSecurityDescriptorOwner (psd, (PSID *) &owner_sid, &dummy))
    debug_printf ("GetSecurityDescriptorOwner %E");
  if (!GetSecurityDescriptorGroup (psd, (PSID *) &group_sid, &dummy))
    debug_printf ("GetSecurityDescriptorGroup %E");

  __uid32_t uid;
  __gid32_t gid;
  bool grp_member = get_sids_info (owner_sid, group_sid, &uid, &gid);
  if (uidret)
    *uidret = uid;
  if (gidret)
    *gidret = gid;

  if (!attribute)
    {
      syscall_printf ("uid %d, gid %d", uid, gid);
      return;
    }

  PACL acl;
  BOOL acl_exists;

  if (!GetSecurityDescriptorDacl (psd, &acl_exists, &acl, &dummy))
    {
      __seterrno ();
      debug_printf ("GetSecurityDescriptorDacl %E");
      *attribute &= ~(S_IRWXU | S_IRWXG | S_IRWXO);
    }
  else if (!acl_exists || !acl)
    *attribute |= S_IRWXU | S_IRWXG | S_IRWXO;
  else
    get_attribute_from_acl (attribute, acl, owner_sid, group_sid, grp_member);

  syscall_printf ("%sACL %x, uid %d, gid %d",
		  (!acl_exists || !acl)?"NO ":"", *attribute, uid, gid);
  return;
}

static void
get_nt_attribute (const char *file, mode_t *attribute,
		  __uid32_t *uidret, __gid32_t *gidret)
{
  security_descriptor sd;

  if (read_sd (file, sd) <= 0)
    debug_printf ("read_sd %E");
  get_info_from_sd (sd, attribute, uidret, gidret);
}

int
get_nt_object_security (HANDLE handle, SE_OBJECT_TYPE object_type,
			security_descriptor &sd_ret)
{
  NTSTATUS ret;
  ULONG len = 0;
  ret = NtQuerySecurityObject (handle,
			       DACL_SECURITY_INFORMATION
			       | GROUP_SECURITY_INFORMATION
			       | OWNER_SECURITY_INFORMATION,
			       sd_ret, len, &len);
  if (ret == STATUS_BUFFER_TOO_SMALL)
    {
      if (!sd_ret.malloc (len))
	set_errno (ENOMEM);
      else
	ret = NtQuerySecurityObject (handle,
				     DACL_SECURITY_INFORMATION
				     | GROUP_SECURITY_INFORMATION
				     | OWNER_SECURITY_INFORMATION,
				     sd_ret, len, &len);
    }
  if (ret != STATUS_SUCCESS)
    {
      __seterrno_from_nt_status (ret);
      return -1;
    }
  return 0;
}

static int
get_nt_object_attribute (HANDLE handle, SE_OBJECT_TYPE object_type,
			 mode_t *attribute, __uid32_t *uidret,
			 __gid32_t *gidret)
{
  security_descriptor sd;
  PSECURITY_DESCRIPTOR psd = NULL;

  if (get_nt_object_security (handle, object_type, sd))
    {
      if (object_type == SE_FILE_OBJECT)
	return -1;
    }
  else
    psd = sd;
  get_info_from_sd (psd, attribute, uidret, gidret);
  return 0;
}

int
get_object_attribute (HANDLE handle, SE_OBJECT_TYPE object_type,
		      mode_t *attribute, __uid32_t *uidret, __gid32_t *gidret)
{
  if (allow_ntsec)
    {
      get_nt_object_attribute (handle, object_type, attribute, uidret, gidret);
      return 0;
    }
  /* The entries are already set to default values */
  return -1;
}

int
get_file_attribute (int use_ntsec, HANDLE handle, const char *file,
		    mode_t *attribute, __uid32_t *uidret, __gid32_t *gidret)
{
  int res;
  syscall_printf ("file: %s", file);

  if (use_ntsec && allow_ntsec)
    {
      if (!handle || get_nt_object_attribute (handle, SE_FILE_OBJECT,
					      attribute, uidret, gidret))
	get_nt_attribute (file, attribute, uidret, gidret);
      return 0;
    }

  if (uidret)
    *uidret = myself->uid;
  if (gidret)
    *gidret = myself->gid;

  if (!attribute)
    return 0;

  if (allow_ntea)
    {
      int oatt = *attribute;
      res = NTReadEA (file, ".UNIXATTR", (char *)attribute, sizeof (*attribute));
      *attribute |= oatt;
    }
  else
    res = 0;

  return res > 0 ? 0 : -1;
}

bool
add_access_allowed_ace (PACL acl, int offset, DWORD attributes,
			PSID sid, size_t &len_add, DWORD inherit)
{
  if (!AddAccessAllowedAce (acl, ACL_REVISION, attributes, sid))
    {
      __seterrno ();
      return false;
    }
  ACCESS_ALLOWED_ACE *ace;
  if (inherit && GetAce (acl, offset, (PVOID *) &ace))
    ace->Header.AceFlags |= inherit;
  len_add += sizeof (ACCESS_ALLOWED_ACE) - sizeof (DWORD) + GetLengthSid (sid);
  return true;
}

bool
add_access_denied_ace (PACL acl, int offset, DWORD attributes,
		       PSID sid, size_t &len_add, DWORD inherit)
{
  if (!AddAccessDeniedAce (acl, ACL_REVISION, attributes, sid))
    {
      __seterrno ();
      return false;
    }
  ACCESS_DENIED_ACE *ace;
  if (inherit && GetAce (acl, offset, (PVOID *) &ace))
    ace->Header.AceFlags |= inherit;
  len_add += sizeof (ACCESS_DENIED_ACE) - sizeof (DWORD) + GetLengthSid (sid);
  return true;
}

static PSECURITY_DESCRIPTOR
alloc_sd (__uid32_t uid, __gid32_t gid, int attribute,
	  security_descriptor &sd_ret)
{
  BOOL dummy;

  debug_printf("uid %d, gid %d, attribute %x", uid, gid, attribute);

  /* Get owner and group from current security descriptor. */
  PSID cur_owner_sid = NULL;
  PSID cur_group_sid = NULL;
  if (!GetSecurityDescriptorOwner (sd_ret, &cur_owner_sid, &dummy))
    debug_printf ("GetSecurityDescriptorOwner %E");
  if (!GetSecurityDescriptorGroup (sd_ret, &cur_group_sid, &dummy))
    debug_printf ("GetSecurityDescriptorGroup %E");

  /* Get SID of owner. */
  cygsid owner_sid;
  /* Check for current user first */
  if (uid == myself->uid)
    owner_sid = cygheap->user.sid ();
  else if (uid == ILLEGAL_UID)
    owner_sid = cur_owner_sid;
  else if (!owner_sid.getfrompw (internal_getpwuid (uid)))
    {
      set_errno (EINVAL);
      return NULL;
    }
  owner_sid.debug_print ("alloc_sd: owner SID =");

  /* Get SID of new group. */
  cygsid group_sid;
  /* Check for current user first */
  if (gid == myself->gid)
    group_sid = cygheap->user.groups.pgsid;
  else if (gid == ILLEGAL_GID)
    group_sid = cur_group_sid;
  else if (!group_sid.getfromgr (internal_getgrgid (gid)))
    {
      set_errno (EINVAL);
      return NULL;
    }
  group_sid.debug_print ("alloc_sd: group SID =");

  /* Initialize local security descriptor. */
  SECURITY_DESCRIPTOR sd;
  if (!InitializeSecurityDescriptor (&sd, SECURITY_DESCRIPTOR_REVISION))
    {
      __seterrno ();
      return NULL;
    }

  /*
   * We set the SE_DACL_PROTECTED flag here to prevent the DACL from being
   * modified by inheritable ACEs.
   * This flag as well as the SetSecurityDescriptorControl call are available
   * only since Win2K.
   */
  if (wincap.has_security_descriptor_control ())
    SetSecurityDescriptorControl (&sd, SE_DACL_PROTECTED, SE_DACL_PROTECTED);

  /* Create owner for local security descriptor. */
  if (!SetSecurityDescriptorOwner (&sd, owner_sid, FALSE))
    {
      __seterrno ();
      return NULL;
    }

  /* Create group for local security descriptor. */
  if (!SetSecurityDescriptorGroup (&sd, group_sid, FALSE))
    {
      __seterrno ();
      return NULL;
    }

  /* Initialize local access control list. */
  PACL acl = (PACL) alloca (3072);
  if (!InitializeAcl (acl, 3072, ACL_REVISION))
    {
      __seterrno ();
      return NULL;
    }

  /* From here fill ACL. */
  size_t acl_len = sizeof (ACL);
  int ace_off = 0;

  /* Construct allow attribute for owner. */
  DWORD owner_allow = STANDARD_RIGHTS_ALL
		      | FILE_WRITE_ATTRIBUTES | FILE_WRITE_EA;
  /* This has nothing to do with traverse checking in the first place, but
     since traverse checking is the setting which switches to POSIX-like
     permission rules, the below is all too similar.  Removing the delete
     bit for a file or directory results in checking the parent directories'
     ACL, if the current user has the FILE_DELETE_CHILD bit set.  This is
     how it is on POSIX systems. */
  if (allow_traverse)
    owner_allow &= ~DELETE;
  if (attribute & S_IRUSR)
    owner_allow |= FILE_GENERIC_READ;
  if (attribute & S_IWUSR)
    owner_allow |= FILE_GENERIC_WRITE;
  if (attribute & S_IXUSR)
    owner_allow |= FILE_GENERIC_EXECUTE;
  if (S_ISDIR (attribute)
      && (attribute & (S_IWUSR | S_IXUSR)) == (S_IWUSR | S_IXUSR))
    owner_allow |= FILE_DELETE_CHILD;

  /* Construct allow attribute for group. */
  DWORD group_allow = STANDARD_RIGHTS_READ
		      | FILE_READ_ATTRIBUTES | FILE_READ_EA;
  if (attribute & S_IRGRP)
    group_allow |= FILE_GENERIC_READ;
  if (attribute & S_IWGRP)
    group_allow |= STANDARD_RIGHTS_WRITE | FILE_GENERIC_WRITE;
  if (attribute & S_IXGRP)
    group_allow |= FILE_GENERIC_EXECUTE;
  if (S_ISDIR (attribute)
      && (attribute & (S_IWGRP | S_IXGRP)) == (S_IWGRP | S_IXGRP)
      && !(attribute & S_ISVTX))
    group_allow |= FILE_DELETE_CHILD;

  /* Construct allow attribute for everyone. */
  DWORD other_allow = STANDARD_RIGHTS_READ
		      | FILE_READ_ATTRIBUTES | FILE_READ_EA;
  if (attribute & S_IROTH)
    other_allow |= FILE_GENERIC_READ;
  if (attribute & S_IWOTH)
    other_allow |= STANDARD_RIGHTS_WRITE | FILE_GENERIC_WRITE;
  if (attribute & S_IXOTH)
    other_allow |= FILE_GENERIC_EXECUTE;
  if (S_ISDIR (attribute)
      && (attribute & (S_IWOTH | S_IXOTH)) == (S_IWOTH | S_IXOTH)
      && !(attribute & S_ISVTX))
    other_allow |= FILE_DELETE_CHILD;

  /* Construct SUID, SGID and VTX bits in NULL ACE. */
  DWORD null_allow = 0L;
  if (attribute & (S_ISUID | S_ISGID | S_ISVTX))
    {
      if (attribute & S_ISUID)
	null_allow |= FILE_APPEND_DATA;
      if (attribute & S_ISGID)
	null_allow |= FILE_WRITE_DATA;
      if (attribute & S_ISVTX)
	null_allow |= FILE_READ_DATA;
    }

  /* Add owner and group permissions if SIDs are equal
     and construct deny attributes for group and owner. */
  bool isownergroup;
  if ((isownergroup = (owner_sid == group_sid)))
    owner_allow |= group_allow;

  DWORD owner_deny = ~owner_allow & (group_allow | other_allow);
  owner_deny &= ~(STANDARD_RIGHTS_READ
		  | FILE_READ_ATTRIBUTES | FILE_READ_EA
		  | FILE_WRITE_ATTRIBUTES | FILE_WRITE_EA);

  DWORD group_deny = ~group_allow & other_allow;
  group_deny &= ~(STANDARD_RIGHTS_READ
		  | FILE_READ_ATTRIBUTES | FILE_READ_EA);

  /* Set deny ACE for owner. */
  if (owner_deny
      && !add_access_denied_ace (acl, ace_off++, owner_deny,
				 owner_sid, acl_len, NO_INHERITANCE))
    return NULL;
  /* Set deny ACE for group here to respect the canonical order,
     if this does not impact owner */
  if (group_deny && !(group_deny & owner_allow) && !isownergroup
      && !add_access_denied_ace (acl, ace_off++, group_deny,
				 group_sid, acl_len, NO_INHERITANCE))
    return NULL;
  /* Set allow ACE for owner. */
  if (!add_access_allowed_ace (acl, ace_off++, owner_allow,
			       owner_sid, acl_len, NO_INHERITANCE))
    return NULL;
  /* Set deny ACE for group, if still needed. */
  if (group_deny & owner_allow && !isownergroup
      && !add_access_denied_ace (acl, ace_off++, group_deny,
				 group_sid, acl_len, NO_INHERITANCE))
    return NULL;
  /* Set allow ACE for group. */
  if (!isownergroup
      && !add_access_allowed_ace (acl, ace_off++, group_allow,
				  group_sid, acl_len, NO_INHERITANCE))
    return NULL;

  /* Set allow ACE for everyone. */
  if (!add_access_allowed_ace (acl, ace_off++, other_allow,
			       well_known_world_sid, acl_len, NO_INHERITANCE))
    return NULL;
  /* Set null ACE for special bits. */
  if (null_allow
      && !add_access_allowed_ace (acl, ace_off++, null_allow,
				  well_known_null_sid, acl_len, NO_INHERITANCE))
    return NULL;

  /* Fill ACL with unrelated ACEs from current security descriptor. */
  PACL oacl;
  BOOL acl_exists = FALSE;
  ACCESS_ALLOWED_ACE *ace;
  if (GetSecurityDescriptorDacl (sd_ret, &acl_exists, &oacl, &dummy)
      && acl_exists && oacl)
    for (DWORD i = 0; i < oacl->AceCount; ++i)
      if (GetAce (oacl, i, (PVOID *) &ace))
	{
	  cygpsid ace_sid ((PSID) &ace->SidStart);

	  /* Check for related ACEs. */
	  if (ace_sid == well_known_null_sid)
	    continue;
	  if ((ace_sid == cur_owner_sid)
	      || (ace_sid == owner_sid)
	      || (ace_sid == cur_group_sid)
	      || (ace_sid == group_sid)
	      || (ace_sid == well_known_world_sid))
	    {
	      if (ace->Header.AceFlags & SUB_CONTAINERS_AND_OBJECTS_INHERIT)
		ace->Header.AceFlags |= INHERIT_ONLY;
	      else
		continue;
	    }
	  /*
	   * Add unrelated ACCESS_DENIED_ACE to the beginning but
	   * behind the owner_deny, ACCESS_ALLOWED_ACE to the end.
	   * FIXME: this would break the order of the inherit_only ACEs
	   */
	  if (!AddAce (acl, ACL_REVISION,
		       ace->Header.AceType == ACCESS_DENIED_ACE_TYPE?
		       (owner_deny ? 1 : 0) : MAXDWORD,
		       (LPVOID) ace, ace->Header.AceSize))
	    {
	      __seterrno ();
	      return NULL;
	    }
	  acl_len += ace->Header.AceSize;
	}

  /* Construct appropriate inherit attribute for new directories */
  if (S_ISDIR (attribute) && !acl_exists)
    {
      const DWORD inherit = SUB_CONTAINERS_AND_OBJECTS_INHERIT | INHERIT_ONLY;

#if 0 /* FIXME: Not done currently as this breaks the canonical order */
      /* Set deny ACE for owner. */
      if (owner_deny
	  && !add_access_denied_ace (acl, ace_off++, owner_deny,
				     well_known_creator_owner_sid, acl_len, inherit))
	return NULL;
      /* Set deny ACE for group here to respect the canonical order,
	 if this does not impact owner */
      if (group_deny && !(group_deny & owner_allow)
	  && !add_access_denied_ace (acl, ace_off++, group_deny,
				     well_known_creator_group_sid, acl_len, inherit))
	return NULL;
#endif
      /* Set allow ACE for owner. */
      if (!add_access_allowed_ace (acl, ace_off++, owner_allow,
				   well_known_creator_owner_sid, acl_len, inherit))
	return NULL;
#if 0 /* FIXME: Not done currently as this breaks the canonical order and
	 won't be preserved on chown and chmod */
      /* Set deny ACE for group, conflicting with owner_allow. */
      if (group_deny & owner_allow
	  && !add_access_denied_ace (acl, ace_off++, group_deny,
				     well_known_creator_group_sid, acl_len, inherit))
	return NULL;
#endif
      /* Set allow ACE for group. */
      if (!add_access_allowed_ace (acl, ace_off++, group_allow,
				   well_known_creator_group_sid, acl_len, inherit))
	return NULL;
      /* Set allow ACE for everyone. */
      if (!add_access_allowed_ace (acl, ace_off++, other_allow,
				   well_known_world_sid, acl_len, inherit))
	return NULL;
    }

  /* Set AclSize to computed value. */
  acl->AclSize = acl_len;
  debug_printf ("ACL-Size: %d", acl_len);

  /* Create DACL for local security descriptor. */
  if (!SetSecurityDescriptorDacl (&sd, TRUE, acl, FALSE))
    {
      __seterrno ();
      return NULL;
    }

  /* Make self relative security descriptor. */
  DWORD sd_size = 0;
  MakeSelfRelativeSD (&sd, sd_ret, &sd_size);
  if (sd_size <= 0)
    {
      __seterrno ();
      return NULL;
    }
  if (!sd_ret.malloc (sd_size))
    {
      set_errno (ENOMEM);
      return NULL;
    }
  if (!MakeSelfRelativeSD (&sd, sd_ret, &sd_size))
    {
      __seterrno ();
      return NULL;
    }
  debug_printf ("Created SD-Size: %u", sd_ret.size ());

  return sd_ret;
}

void
set_security_attribute (int attribute, PSECURITY_ATTRIBUTES psa,
			security_descriptor &sd)
{
  psa->lpSecurityDescriptor = sd.malloc (SECURITY_DESCRIPTOR_MIN_LENGTH);
  InitializeSecurityDescriptor ((PSECURITY_DESCRIPTOR)psa->lpSecurityDescriptor,
				SECURITY_DESCRIPTOR_REVISION);
  psa->lpSecurityDescriptor = alloc_sd (geteuid32 (), getegid32 (),
					attribute, sd);
}

static int
set_nt_attribute (HANDLE handle, const char *file,
		  __uid32_t uid, __gid32_t gid, int attribute)
{
  if (!wincap.has_security ())
    return 0;

  security_descriptor sd;

  if ((!handle || get_nt_object_security (handle, SE_FILE_OBJECT, sd))
      && read_sd (file, sd) <= 0)
    {
      debug_printf ("read_sd %E");
      return -1;
    }

  if (!alloc_sd (uid, gid, attribute, sd))
    return -1;

  return write_sd (handle, file, sd);
}

int
set_file_attribute (bool use_ntsec, HANDLE handle, const char *file,
		    __uid32_t uid, __gid32_t gid, int attribute)
{
  int ret = 0;

  if (use_ntsec && allow_ntsec)
    ret = set_nt_attribute (handle, file, uid, gid, attribute);
  else if (allow_ntea && !NTWriteEA (file, ".UNIXATTR", (char *) &attribute,
				     sizeof (attribute)))
    {
      __seterrno ();
      ret = -1;
    }
  syscall_printf ("%d = set_file_attribute (%s, %d, %d, %p)",
		  ret, file, uid, gid, attribute);
  return ret;
}

int
set_file_attribute (bool use_ntsec, HANDLE handle, const char *file,
		    int attribute)
{
  return set_file_attribute (use_ntsec, handle, file,
			     myself->uid, myself->gid, attribute);
}

int
check_file_access (const char *fn, int flags)
{
  int ret = -1;

  security_descriptor sd;

  HANDLE hToken;
  BOOL status;
  char pbuf[sizeof (PRIVILEGE_SET) + 3 * sizeof (LUID_AND_ATTRIBUTES)];
  DWORD desired = 0, granted, plength = sizeof pbuf;
  static GENERIC_MAPPING NO_COPY mapping = { FILE_GENERIC_READ,
					     FILE_GENERIC_WRITE,
					     FILE_GENERIC_EXECUTE,
					     FILE_ALL_ACCESS };
  if (read_sd (fn, sd) <= 0)
    goto done;

  if (cygheap->user.issetuid ())
    hToken = cygheap->user.token ();
  else
    hToken = hProcImpToken;

  if (flags & R_OK)
    desired |= FILE_READ_DATA;
  if (flags & W_OK)
    desired |= FILE_WRITE_DATA;
  if (flags & X_OK)
    desired |= FILE_EXECUTE;
  if (!AccessCheck (sd, hToken, desired, &mapping,
		    (PPRIVILEGE_SET) pbuf, &plength, &granted, &status))
    __seterrno ();
  else if (!status)
    set_errno (EACCES);
  else
    ret = 0;
 done:
  debug_printf ("flags %x, ret %d", flags, ret);
  return ret;
}