* Makefile.in (DLL_OFILES): Add setlsapwd.o.

* cygserver.h (CYGWIN_SERVER_VERSION_API): Bump.
	(request_code_t): Define CYGSERVER_REQUEST_SETPWD request type.
	* cygserver_msg.h (client_request_msg::retval): Use default value of -1
	for retval if msglen is 0.
	* cygserver_sem.h (client_request_sem::retval): Ditto.
	* cygserver_shm.h (client_request_shm::retval): Ditto.
	* cygserver_setpwd.h: New file.
	* external.cc (cygwin_internal): Implement new CW_SET_PRIV_KEY type.
	* sec_auth.cc (open_local_policy): Make externally available.
	Get ACCESS_MASK as argument.
	(create_token): Accommodate change to open_local_policy.
	(lsaauth): Ditto.
	(lsaprivkeyauth): New function fetching token by retrieving
	password stored in Cygwin or Interix LSA private data area and
	calling LogonUser with it.
	* security.h (lsaprivkeyauth): Declare.
	(open_local_policy): Declare.
	* setlsapwd.cc: New file implementing setting LSA private data password
	using LsaStorePrivateData or by calling cygserver if available.
	* syscalls.cc (seteuid32): Add workaround to get the original token
	when switching back to the original privileged user, even if
	setgroups group list is still active.  Add long comment to explain why.
	Call lsaprivkeyauth first, only if that fails call lsaauth or
	create_token.
	* include/cygwin/version.h: Bump API minor number.
	* include/sys/cygwin.h (cygwin_getinfo_types): Add CW_SET_PRIV_KEY.

winsup/cygwin/sec_auth.cc

@@ -27,6 +27,7 @@ details. */
 #include <iptypes.h>
 #include "pwdgrp.h"
 #include "cyglsa.h"
+#include "cygserver_setpwd.h"
 #include <cygwin/version.h>
 
 extern "C" void
@@ -150,13 +151,13 @@ str2uni_cat (UNICODE_STRING &tgt, const char *srcstr)
     tgt.Length = tgt.MaximumLength = 0;
 }
 
-static LSA_HANDLE
-open_local_policy ()
+HANDLE
+open_local_policy (ACCESS_MASK access)
 {
   LSA_OBJECT_ATTRIBUTES oa = { 0, 0, 0, 0, 0, 0 };
-  LSA_HANDLE lsa = INVALID_HANDLE_VALUE;
+  HANDLE lsa = INVALID_HANDLE_VALUE;
 
-  NTSTATUS ret = LsaOpenPolicy (NULL, &oa, POLICY_EXECUTE, &lsa);
+  NTSTATUS ret = LsaOpenPolicy (NULL, &oa, access, &lsa);
   if (ret != STATUS_SUCCESS)
     __seterrno_from_win_error (LsaNtStatusToWinError (ret));
   return lsa;
@@ -785,7 +786,7 @@ create_token (cygsid &usersid, user_groups &new_groups, struct passwd *pw)
   push_self_privilege (SE_CREATE_TOKEN_PRIVILEGE, true);
 
   /* Open policy object. */
-  if ((lsa = open_local_policy ()) == INVALID_HANDLE_VALUE)
+  if ((lsa = open_local_policy (POLICY_EXECUTE)) == INVALID_HANDLE_VALUE)
     goto out;
 
   /* User, owner, primary group. */
@@ -963,7 +964,7 @@ lsaauth (cygsid &usersid, user_groups &new_groups, struct passwd *pw)
     }
 
   /* Open policy object. */
-  if ((lsa = open_local_policy ()) == INVALID_HANDLE_VALUE)
+  if ((lsa = open_local_policy (POLICY_EXECUTE)) == INVALID_HANDLE_VALUE)
     goto out;
 
   /* Create origin. */
@@ -1172,3 +1173,75 @@ out:
   debug_printf ("%p = lsaauth ()", user_token);
   return user_token;
 }
+
+#define SFU_LSA_KEY_SUFFIX	L"_microsoft_sfu_utility"
+
+HANDLE
+lsaprivkeyauth (struct passwd *pw)
+{
+  NTSTATUS status;
+  HANDLE lsa = INVALID_HANDLE_VALUE;
+  HANDLE token = NULL;
+  WCHAR sid[256];
+  WCHAR domain[MAX_DOMAIN_NAME_LEN + 1];
+  WCHAR user[UNLEN + 1];
+  WCHAR key_name[MAX_DOMAIN_NAME_LEN + UNLEN + wcslen (SFU_LSA_KEY_SUFFIX) + 2];
+  UNICODE_STRING key;
+  PUNICODE_STRING data;
+  cygsid psid;
+
+  push_self_privilege (SE_TCB_PRIVILEGE, true);
+
+  /* Open policy object. */
+  if ((lsa = open_local_policy (POLICY_GET_PRIVATE_INFORMATION))
+      == INVALID_HANDLE_VALUE)
+    goto out;
+
+  /* Needed for Interix key and LogonUser. */
+  extract_nt_dom_user (pw, domain, user);
+
+  /* First test for a Cygwin entry. */
+  if (psid.getfrompw (pw) && psid.string (sid))
+    {
+      wcpcpy (wcpcpy (key_name, CYGWIN_LSA_KEY_PREFIX), sid);
+      RtlInitUnicodeString (&key, key_name);
+      status = LsaRetrievePrivateData (lsa, &key, &data);
+      if (!NT_SUCCESS (status))
+	{
+	  /* No Cygwin key, try Interix key. */
+	  if (!*domain)
+	    goto out;
+	  __small_swprintf (key_name, L"%W_%W%W",
+			    domain, user, SFU_LSA_KEY_SUFFIX);
+	  RtlInitUnicodeString (&key, key_name);
+	  status = LsaRetrievePrivateData (lsa, &key, &data);
+	  if (!NT_SUCCESS (status))
+	    goto out;
+	}
+    }
+
+  /* The key is not 0-terminated. */
+  PWCHAR passwd = (PWCHAR) alloca (data->Length + sizeof (WCHAR));
+  *wcpncpy (passwd, data->Buffer, data->Length / sizeof (WCHAR)) = L'\0';
+  LsaFreeMemory (data);
+  debug_printf ("Try logon for %W\\%W", domain, user);
+  if (!LogonUserW (user, domain, passwd, LOGON32_LOGON_INTERACTIVE,
+		   LOGON32_PROVIDER_DEFAULT, &token))
+    {
+      __seterrno ();
+      token = NULL;
+    }
+  else if (!SetHandleInformation (token,
+				  HANDLE_FLAG_INHERIT,
+				  HANDLE_FLAG_INHERIT))
+    {
+      __seterrno ();
+      CloseHandle (token);
+      token = NULL;
+    }
+
+out:
+  close_local_policy (lsa);
+  pop_self_privilege ();
+  return token;
+}