* syscalls.cc (seteuid): Set default dacl in process token.

Replace in-line code by call to verify_token().
	(setegid): Reverse change from 2002-01-21. Add call to
	RevertToSelf and set primary group in impersonation token.
	* security.cc (create_token): Store pgrpsid in token security
	descriptor, except if it already appears in my_grps.
	Use sec_acl() in place of get_dacl().
	(verify_token): Create from code in seteuid(), with tighter checks.
	(get_dacl) Deleted.
	(get_group_sidlist): Add argument to indicate if pgrpsid is already
	in the groups.
	* security.h: Define verify_token().
	* autoload.cc: Load GetKernelObjectSecurity().

winsup/cygwin/ChangeLog

@@ -1,3 +1,19 @@
+2002-05-13  Pierre Humblet <pierre.humblet@ieee.org>
+
+	* syscalls.cc (seteuid): Set default dacl in process token.
+	Replace in-line code by call to verify_token().
+	(setegid): Reverse change from 2002-01-21. Add call to
+	RevertToSelf and set primary group in impersonation token.
+	* security.cc (create_token): Store pgrpsid in token security
+	descriptor, except if it already appears in my_grps.
+	Use sec_acl() in place of get_dacl().
+	(verify_token): Create from code in seteuid(), with tighter checks.
+	(get_dacl) Deleted.
+	(get_group_sidlist): Add argument to indicate if pgrpsid is already
+	in the groups.
+	* security.h: Define verify_token().
+	* autoload.cc: Load GetKernelObjectSecurity().
+
 2002-05-13  Mark Bradshaw  <bradshaw@staff.crosswalk.com>
 
 	* cygwin.din: Add strlcat and strlcpy.

winsup/cygwin/autoload.cc

@@ -316,6 +316,7 @@ LoadDLLfuncEx (DuplicateTokenEx, 24, advapi32, 1)
 LoadDLLfunc (EqualSid, 8, advapi32)
 LoadDLLfunc (GetAce, 12, advapi32)
 LoadDLLfunc (GetFileSecurityA, 20, advapi32)
+LoadDLLfunc (GetKernelObjectSecurity, 20, advapi32)
 LoadDLLfunc (GetLengthSid, 4, advapi32)
 LoadDLLfunc (GetSecurityDescriptorDacl, 16, advapi32)
 LoadDLLfunc (GetSecurityDescriptorGroup, 12, advapi32)

winsup/cygwin/security.cc

@@ -476,7 +476,8 @@ get_supplementary_group_sidlist (const char *username, cygsidlist &grp_list)
 static BOOL
 get_group_sidlist (const char *logonserver, cygsidlist &grp_list,
 		   cygsid &usersid, cygsid &pgrpsid,
-		   PTOKEN_GROUPS my_grps, LUID auth_luid, int &auth_pos)
+		   PTOKEN_GROUPS my_grps, LUID auth_luid, int &auth_pos,
+		   BOOL * special_pgrp)
 {
   WCHAR wserver[INTERNET_MAX_HOST_NAME_LENGTH + 1];
   char user[INTERNET_MAX_HOST_NAME_LENGTH + 1];
@@ -533,19 +534,25 @@ get_group_sidlist (const char *logonserver, cygsidlist &grp_list,
 	  auth_pos = grp_list.count - 1;
 	}
     }
+  /* special_pgrp true if pgrpsid is not null and not in normal groups */
   if (!pgrpsid)
-    get_user_primary_group (wserver, user, usersid, pgrpsid);
+    {
+      * special_pgrp = FALSE;
+      get_user_primary_group (wserver, user, usersid, pgrpsid);
+    }
+  else * special_pgrp = TRUE;
   if (!get_user_groups (wserver, grp_list, user) ||
       !get_user_local_groups (wserver, logonserver, grp_list, usersid))
     return FALSE;
-  if (!grp_list.contains (pgrpsid))
-    grp_list += pgrpsid;
   if (get_supplementary_group_sidlist (user, sup_list))
     {
       for (int i = 0; i < sup_list.count; ++i)
 	if (!grp_list.contains (sup_list.sids[i]))
 	  grp_list += sup_list.sids[i];
     }
+  if (!grp_list.contains (pgrpsid))
+    grp_list += pgrpsid;
+  else * special_pgrp = FALSE;
   return TRUE;
 }
 
@@ -663,38 +670,56 @@ get_priv_list (LSA_HANDLE lsa, cygsid &usersid, cygsidlist &grp_list)
   return privs;
 }
 
-#define token_acl_size (sizeof (ACL) + \
+BOOL
-			2 * (sizeof (ACCESS_ALLOWED_ACE) + MAX_SID_LEN))
+verify_token (HANDLE token, cygsid &usersid, cygsid &pgrpsid, BOOL * pintern)
-
-static BOOL
-get_dacl (PACL acl, cygsid usersid, cygsidlist &grp_list)
 {
-  if (!InitializeAcl(acl, token_acl_size, ACL_REVISION))
+  DWORD size;
+  BOOL intern = FALSE;
+
+  if (pintern)
     {
-      __seterrno ();
+      TOKEN_SOURCE ts;
-      return FALSE;
+      if (!GetTokenInformation (cygheap->user.token, TokenSource,
+				&ts, sizeof ts, &size))
+	debug_printf ("GetTokenInformation(): %E");
+      else *pintern = intern = !memcmp (ts.SourceName, "Cygwin.1", 8);
     }
-  if (grp_list.contains (well_known_admins_sid))
+  /* 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;
+
+  /* In an internal token, if the sd group is not well_known_null_sid,
+     it must match pgrpsid */
+  if (intern)
     {
-      if (!AddAccessAllowedAce(acl, ACL_REVISION, GENERIC_ALL,
+       char sd_buf[MAX_SID_LEN + sizeof (SECURITY_DESCRIPTOR)];
-			       well_known_admins_sid))
+       PSID gsid = NO_SID;
-	{
+       if (!GetKernelObjectSecurity(token, GROUP_SECURITY_INFORMATION,
-	  __seterrno ();
+				    (PSECURITY_DESCRIPTOR) sd_buf,
-	  return FALSE;
+				    sizeof sd_buf, &size))
-	}
+	   debug_printf ("GetKernelObjectSecurity(): %E");
+       else if (!GetSecurityDescriptorGroup((PSECURITY_DESCRIPTOR) sd_buf,
+					    &gsid, (BOOL *) &size))
+	   debug_printf ("GetSecurityDescriptorGroup(): %E");
+       if (well_known_null_sid != gsid) return pgrpsid == gsid;
     }
-  else if (!AddAccessAllowedAce(acl, ACL_REVISION, GENERIC_ALL, usersid))
+  /* See if the pgrpsid is in the token groups */
-    {
+  PTOKEN_GROUPS my_grps = NULL;
-      __seterrno ();
+  BOOL ret = FALSE;
-      return FALSE;
+
-    }
+  if (!GetTokenInformation (token, TokenGroups, NULL, 0, &size) &&
-  if (!AddAccessAllowedAce(acl, ACL_REVISION, GENERIC_ALL,
+	  GetLastError () != ERROR_INSUFFICIENT_BUFFER)
-			   well_known_system_sid))
+	debug_printf ("GetTokenInformation(token, TokenGroups): %E\n");
-    {
+  else if (!(my_grps = (PTOKEN_GROUPS) malloc (size)))
-      __seterrno ();
+	debug_printf ("malloc (my_grps) failed.");
-      return FALSE;
+  else if (!GetTokenInformation (token, TokenGroups, my_grps, size, &size))
-    }
+	debug_printf ("GetTokenInformation(my_token, TokenGroups): %E\n");
-  return TRUE;
+  else 	ret = sid_in_token_groups (my_grps, pgrpsid);
+  if (my_grps) free (my_grps);
+  return ret;
 }
 
 HANDLE
@@ -711,6 +736,8 @@ create_token (cygsid &usersid, cygsid &pgrpsid)
     { sizeof sqos, SecurityImpersonation, SECURITY_STATIC_TRACKING, FALSE };
   OBJECT_ATTRIBUTES oa =
     { sizeof oa, 0, 0, 0, 0, &sqos };
+  PSECURITY_ATTRIBUTES psa;
+  BOOL special_pgrp;
   char sa_buf[1024];
   LUID auth_luid = SYSTEM_LUID;
   LARGE_INTEGER exp = { QuadPart:0x7fffffffffffffffLL  };
@@ -720,7 +747,7 @@ create_token (cygsid &usersid, cygsid &pgrpsid)
   PTOKEN_PRIVILEGES privs = NULL;
   TOKEN_OWNER owner;
   TOKEN_PRIMARY_GROUP pgrp;
-  char acl_buf[token_acl_size];
+  char acl_buf[MAX_DACL_LEN(5)];
   TOKEN_DEFAULT_DACL dacl;
   TOKEN_SOURCE source;
   TOKEN_STATISTICS stats;
@@ -786,7 +813,7 @@ create_token (cygsid &usersid, cygsid &pgrpsid)
   /* Create list of groups, the user is member in. */
   int auth_pos;
   if (!get_group_sidlist (logonserver, grpsids, usersid, pgrpsid,
-			  my_grps, auth_luid, auth_pos))
+			  my_grps, auth_luid, auth_pos, &special_pgrp))
     goto out;
 
   /* Primary group. */
@@ -811,7 +838,8 @@ create_token (cygsid &usersid, cygsid &pgrpsid)
     goto out;
 
   /* Create default dacl. */
-  if (!get_dacl ((PACL) acl_buf, usersid, grpsids))
+  if (!sec_acl((PACL) acl_buf, FALSE,
+		grpsids.contains (well_known_admins_sid)?well_known_admins_sid:usersid))
     goto out;
   dacl.DefaultDacl = (PACL) acl_buf;
 
@@ -826,11 +854,22 @@ create_token (cygsid &usersid, cygsid &pgrpsid)
       __seterrno ();
       debug_printf ("Loading NtCreateToken failed.");
     }
-
+  else
-  /* Convert to primary token. */
+    {
-  if (!DuplicateTokenEx (token, MAXIMUM_ALLOWED, sec_user (sa_buf, usersid),
+      /* Set security descriptor and primary group */
-			 SecurityImpersonation, TokenPrimary, &primary_token))
+      psa = sec_user (sa_buf, usersid);
-    __seterrno ();
+      if (!SetSecurityDescriptorGroup (
+                   (PSECURITY_DESCRIPTOR) psa->lpSecurityDescriptor,
+                   special_pgrp?pgrpsid:well_known_null_sid, FALSE))
+          debug_printf ("SetSecurityDescriptorGroup %E");
+      /* Convert to primary token. */
+      if (!DuplicateTokenEx (token, MAXIMUM_ALLOWED, psa,
+                             SecurityImpersonation, TokenPrimary, &primary_token))
+        {
+          __seterrno ();
+          debug_printf ("DuplicateTokenEx %E");
+        }
+    }
 
 out:
   if (old_priv_state >= 0)

winsup/cygwin/security.h

@@ -181,6 +181,8 @@ void set_security_attribute (int attribute, PSECURITY_ATTRIBUTES psa,
 HANDLE subauth (struct passwd *pw);
 /* Try creating a token directly. */
 HANDLE create_token (cygsid &usersid, cygsid &pgrpsid);
+/* Verify an existing token */
+BOOL verify_token (HANDLE token, cygsid &usersid, cygsid &pgrpsid, BOOL * pintern = NULL);
 
 /* Extract U-domain\user field from passwd entry. */
 void extract_nt_dom_user (const struct passwd *pw, char *domain, char *user);

winsup/cygwin/syscalls.cc

@@ -2007,7 +2007,7 @@ seteuid (__uid16_t uid)
 	}
       else
 	{
-	  cygsid usersid, pgrpsid, tok_pgrpsid;
+	  cygsid usersid, pgrpsid, origsid;
 	  HANDLE sav_token = INVALID_HANDLE_VALUE;
 	  BOOL sav_impersonation;
 	  BOOL current_token_is_internal_token = FALSE;
@@ -2024,31 +2024,8 @@ seteuid (__uid16_t uid)
 	     - if reasonable - new pgrp == pgrp of impersonation token. */
 	  if (allow_ntsec && cygheap->user.token != INVALID_HANDLE_VALUE)
 	    {
-	      if (!GetTokenInformation (cygheap->user.token, TokenUser,
+	      if (!verify_token(cygheap->user.token, usersid, pgrpsid,
-					&tok_usersid, sizeof tok_usersid, &siz))
+				& current_token_is_internal_token))
-		{
-		  debug_printf ("GetTokenInformation(): %E");
-		  tok_usersid = NO_SID;
-		}
-	      if (!GetTokenInformation (cygheap->user.token, TokenPrimaryGroup,
-					&tok_pgrpsid, sizeof tok_pgrpsid, &siz))
-		{
-		  debug_printf ("GetTokenInformation(): %E");
-		  tok_pgrpsid = NO_SID;
-		}
-	      /* Check if the current user token was internally created. */
-	      TOKEN_SOURCE ts;
-	      if (!GetTokenInformation (cygheap->user.token, TokenSource,
-					&ts, sizeof ts, &siz))
-		debug_printf ("GetTokenInformation(): %E");
-	      else if (!memcmp (ts.SourceName, "Cygwin.1", 8))
-		current_token_is_internal_token = TRUE;
-	      if ((usersid && tok_usersid && usersid != tok_usersid) ||
-		  /* Check for pgrp only if current token is an internal
-		     token. Otherwise the external provided token is
-		     very likely overwritten here. */
-		  (current_token_is_internal_token &&
-		   pgrpsid && tok_pgrpsid && pgrpsid != tok_pgrpsid))
 		{
 		  /* If not, RevertToSelf and close old token. */
 		  debug_printf ("tsid != usersid");
@@ -2113,9 +2090,28 @@ seteuid (__uid16_t uid)
 					    &pgrpsid, sizeof pgrpsid))
 		    debug_printf ("SetTokenInformation(user.token, "
 				  "TokenPrimaryGroup): %E");
-
 		}
-
+	      /* Set process def dacl to allow access to impersonated token */
+	      char dacl_buf[MAX_DACL_LEN(5)];
+	      origsid = cygheap->user.orig_sid ();
+	      if (usersid && origsid &&
+		  sec_acl((PACL) dacl_buf, FALSE, origsid, usersid))
+	        {
+		  HANDLE ptok = INVALID_HANDLE_VALUE;
+		  TOKEN_DEFAULT_DACL tdacl;
+		  tdacl.DefaultDacl = (PACL) dacl_buf;
+		  if (!OpenProcessToken (GetCurrentProcess (), TOKEN_ADJUST_DEFAULT,
+					 &ptok))
+		    debug_printf ("OpenProcessToken(): %E");
+		  else
+		    {
+		      if (!SetTokenInformation (ptok, TokenDefaultDacl,
+						&tdacl, sizeof dacl_buf))
+			debug_printf ("SetTokenInformation"
+				      "(TokenDefaultDacl): %E");
+		    }
+		  if (ptok != INVALID_HANDLE_VALUE) CloseHandle (ptok);
+		}
 	      /* Now try to impersonate. */
 	      if (!LookupAccountSid (NULL, usersid, username, &ulen,
 				     domain, &dlen, &use))
@@ -2180,7 +2176,6 @@ setegid (__gid16_t gid)
 	      return -1;
 	    }
 	  myself->gid = gid;
-#if 0	  // Setting the primary group in token here isn't foolproof enough.
 	  if (allow_ntsec)
 	    {
 	      cygsid gsid;
@@ -2188,6 +2183,17 @@ setegid (__gid16_t gid)
 
 	      if (gsid.getfromgr (gr))
 		{
+		  /* Remove impersonation */
+		  if (cygheap->user.token != INVALID_HANDLE_VALUE
+		      && cygheap->user.impersonated)
+		    {
+		      if (!SetTokenInformation (cygheap->user.token,
+						TokenPrimaryGroup,
+						&gsid, sizeof gsid))
+			debug_printf ("SetTokenInformation(primary, "
+				      "TokenPrimaryGroup): %E");
+		      RevertToSelf ();
+		    }
 		  if (!OpenProcessToken (GetCurrentProcess (),
 					 TOKEN_ADJUST_DEFAULT,
 					 &ptok))
@@ -2196,13 +2202,15 @@ setegid (__gid16_t gid)
 		    {
 		      if (!SetTokenInformation (ptok, TokenPrimaryGroup,
 						&gsid, sizeof gsid))
-			debug_printf ("SetTokenInformation(myself, "
+			debug_printf ("SetTokenInformation(process, "
 				      "TokenPrimaryGroup): %E");
 		      CloseHandle (ptok);
 		    }
+		  if (cygheap->user.token != INVALID_HANDLE_VALUE
+		      && cygheap->user.impersonated)
+		    ImpersonateLoggedOnUser (cygheap->user.token);
 		}
 	    }
-#endif
 	}
     }
   else