Il problema qui è che mentre il certificato collega la procedura memorizzata in DatabaseA con l'utente in DatabaseB che dispone delle INSERT
autorizzazioni per le due tabelle, il trigger sulla tabella da inserire direttamente dalla procedura memorizzata è un altro modulo della catena e le autorizzazioni acquisite dai certificati non passano ad altri moduli in una catena. In altre parole, il Certificato consentiva alla Procedura memorizzata di essere inserita nella tabella tramite l'utente e persino di eseguire il trigger. Tuttavia, al trigger non sono state concesse autorizzazioni per eseguire operazioni relative agli oggetti (fare qualcosa del genere SELECT 1;
funzionerebbe).
In questo caso, è necessario assegnare le autorizzazioni al trigger tramite lo stesso certificato, in modo che possa intraprendere tutte le azioni necessarie. Ciò può essere realizzato, per lo meno, controfirmando il trigger. E lo fai eseguendo ADD COUNTER SIGNATURE TO [TriggerSchema].[TriggerName] BY CERTIFICATE ...;
. Dopodiché, dovrebbe funzionare, anche senza l' INSERT
autorizzazione diretta per l'utente basato sul certificato sulla tabella che viene inserita dal trigger.
Il seguente codice di esempio riproduce il problema, risolve il problema aggiungendo una firma contatore, ma non concede le INSERT
autorizzazioni alla tabella popolata da trigger.
PULIRE
USE [master];
GO
IF EXISTS (SELECT 1 FROM [sys].[databases] WHERE [name] = N'DatabaseA')
BEGIN
PRINT 'Dropping [DatabaseA] DB...';
ALTER DATABASE [DatabaseA] SET OFFLINE WITH ROLLBACK IMMEDIATE;
ALTER DATABASE [DatabaseA] SET ONLINE;
DROP DATABASE [DatabaseA];
END;
IF EXISTS (SELECT 1 FROM [sys].[databases] WHERE [name] = N'DatabaseB')
BEGIN
PRINT 'Dropping [DatabaseB] DB...';
ALTER DATABASE [DatabaseB] SET OFFLINE WITH ROLLBACK IMMEDIATE;
ALTER DATABASE [DatabaseB] SET ONLINE;
DROP DATABASE [DatabaseB];
END;
IF (SUSER_ID(N'JohnnyLunchbucket') IS NOT NULL)
BEGIN
PRINT 'Dropping [JohnnyLunchbucket] Login...';
DROP LOGIN [JohnnyLunchbucket];
END;
IF (OBJECT_ID(N'tempdb..#CertInfo') IS NOT NULL)
BEGIN
PRINT 'Dropping [#CertInfo] Temp Table...';
DROP TABLE #CertInfo;
END;
IMPOSTARE
USE [master];
EXECUTE AS LOGIN = N'sa';
PRINT 'Creating databases...';
CREATE DATABASE [DatabaseA] COLLATE Latin1_General_100_CI_AS_SC;
CREATE DATABASE [DatabaseB] COLLATE Latin1_General_100_CI_AS_SC;
REVERT;
GO
-- Default for both options should be OFF, but just to be sure:
ALTER DATABASE [DatabaseA] SET DB_CHAINING OFF;
ALTER DATABASE [DatabaseA] SET TRUSTWORTHY OFF;
ALTER DATABASE [DatabaseB] SET DB_CHAINING OFF;
ALTER DATABASE [DatabaseB] SET TRUSTWORTHY OFF;
GO
CREATE LOGIN [JohnnyLunchbucket] WITH PASSWORD = 'OhSoSecure;)';
USE [DatabaseA];
CREATE USER [JohnnyLunchbucket] FOR LOGIN [JohnnyLunchbucket];
GO
--DROP PROCEDURE dbo.InsertIntoTableWithoutTrigger;
CREATE PROCEDURE dbo.InsertIntoTableWithoutTrigger
(
@SomeValue NVARCHAR(50)
)
AS
SET NOCOUNT ON;
INSERT INTO [DatabaseB].[dbo].[TableWithoutTrigger] (SomeValue)
VALUES (@SomeValue);
GO
GRANT EXECUTE ON dbo.InsertIntoTableWithoutTrigger TO [JohnnyLunchbucket];
GO
CREATE PROCEDURE dbo.InsertIntoTableWithTrigger
AS
SET NOCOUNT ON;
INSERT INTO [DatabaseB].[dbo].[TableWithTrigger] (SomeOtherValue)
VALUES (NEWID());
GO
GRANT EXECUTE ON dbo.InsertIntoTableWithTrigger TO [JohnnyLunchbucket];
CREATE CERTIFICATE [PermissionsCert]
AUTHORIZATION [dbo]
ENCRYPTION BY PASSWORD = 'WeakPassword'
WITH SUBJECT = 'Used to test granting permissions to code',
EXPIRY_DATE = '2099-12-31';
ADD SIGNATURE TO [dbo].[InsertIntoTableWithoutTrigger]
BY CERTIFICATE [PermissionsCert]
WITH PASSWORD = 'WeakPassword';
ADD SIGNATURE TO [dbo].[InsertIntoTableWithTrigger]
BY CERTIFICATE [PermissionsCert]
WITH PASSWORD = 'WeakPassword';
-- Save Certificate info in temporary table so we can recreate in DatabaseB
SELECT CERTENCODED(CERT_ID(N'PermissionsCert')) AS [PublicKey],
CERTPRIVATEKEY(CERT_ID(N'PermissionsCert'), 'OtherPassword', 'WeakPassword')
AS [PrivateKey]
INTO #CertInfo;
GO
USE [DatabaseB];
DECLARE @SQL NVARCHAR(MAX);
SELECT @SQL = N'CREATE CERTIFICATE [PermissionsCert] AUTHORIZATION [dbo] FROM BINARY = '
+ CONVERT(NVARCHAR(MAX), [PublicKey], 1)
+ N' WITH PRIVATE KEY (BINARY = '
+ CONVERT(NVARCHAR(MAX), [PrivateKey], 1)
+ N', DECRYPTION BY PASSWORD = N''OtherPassword'''
+ N', ENCRYPTION BY PASSWORD = ''WeakPassword'');'
FROM #CertInfo;
PRINT @SQL;
EXEC (@SQL);
CREATE USER [PermissionsUser] FROM CERTIFICATE [PermissionsCert];
--DROP TABLE dbo.[TableWithoutTrigger];
CREATE TABLE dbo.[TableWithoutTrigger]
(
[TableWithoutTriggerID] INT NOT NULL IDENTITY(1, 1)
CONSTRAINT [PK_TableWithoutTrigger] PRIMARY KEY,
[SomeValue] NVARCHAR(50)
);
GRANT INSERT ON [dbo].[TableWithoutTrigger] TO [PermissionsUser];
CREATE TABLE dbo.[TableWithTrigger]
(
[TableWithTriggerID] INT NOT NULL IDENTITY(1, 1)
CONSTRAINT [PK_TableWithTrigger] PRIMARY KEY,
[SomeOtherValue] NVARCHAR(50)
);
GRANT INSERT ON [dbo].[TableWithTrigger] TO [PermissionsUser];
CREATE TABLE dbo.[TablePopulatedByTrigger]
(
[TablePopulatedByTriggerID] INT NOT NULL IDENTITY(1, 1)
CONSTRAINT [PK_TablePopulatedByTrigger] PRIMARY KEY,
[DuplicatedValue] NVARCHAR(50)
);
GO
CREATE TRIGGER dbo.CopySomeOtherValue
ON dbo.[TableWithTrigger]
AFTER INSERT
AS
BEGIN
SET NOCOUNT ON;
INSERT INTO dbo.[TablePopulatedByTrigger] ([DuplicatedValue])
SELECT ins.[SomeOtherValue]
FROM inserted ins;
END;
GO
TEST 1: il trigger ha esito negativo
USE [DatabaseA];
EXECUTE AS LOGIN = 'JohnnyLunchbucket';
SELECT SESSION_USER AS [User], ORIGINAL_LOGIN() AS [OriginalLogin];
GO
SELECT * FROM [DatabaseB].[dbo].[TableWithoutTrigger];
SELECT * FROM [DatabaseB].[dbo].[TableWithTrigger];
SELECT * FROM [DatabaseB].[dbo].[TablePopulatedByTrigger];
INSERT INTO [DatabaseB].[dbo].[TableWithoutTrigger] ([SomeValue]) VALUES (N'test 0');
USE [DatabaseB];
/* -- All 5 statements above get the following error:
Msg 916, Level 14, State 1, Line xxxxxx
The server principal "JohnnyLunchbucket" is not able to access the database
"DatabaseB" under the current security context.
*/
EXEC [dbo].[InsertIntoTableWithoutTrigger] @SomeValue = N'test A'; -- SUCCESS!!!
EXEC [dbo].[InsertIntoTableWithTrigger]; -- ERROR:
/*
Msg 916, Level 14, State 1, Procedure CopySomeOtherValue, Line xxxxxx
The server principal "JohnnyLunchbucket" is not able to access the database
"DatabaseB" under the current security context.
*/
REVERT;
SELECT SESSION_USER AS [User], ORIGINAL_LOGIN() AS [OriginalLogin];
-- Check to make sure that dbo.InsertIntoTableWithoutTrigger really did work:
SELECT * FROM [DatabaseB].[dbo].[TableWithoutTrigger];
-- 1 test A
TEST 2: il trigger ha esito positivo
Si noti che l' unica modifica apportata è ADD COUNTER SIGNATURE
; non c'è GRANT INSERT ON dbo.TablePopulatedByTrigger TO [PermissionsUser];
.
USE [DatabaseB];
ADD COUNTER SIGNATURE
TO dbo.[CopySomeOtherValue]
BY CERTIFICATE [PermissionsCert]
WITH PASSWORD = 'WeakPassword';
GO
USE [DatabaseA];
EXECUTE AS LOGIN = 'JohnnyLunchbucket';
SELECT SESSION_USER AS [User], ORIGINAL_LOGIN() AS [OriginalLogin];
GO
INSERT INTO [DatabaseB].[dbo].[TableWithTrigger] ([SomeOtherValue]) VALUES (N'Test B');
INSERT INTO [DatabaseB].[dbo].[TablePopulatedByTrigger]([DuplicatedValue]) VALUES ('Test B')
/*
Msg 916, Level 14, State 1, Line xxxxxx
The server principal "JohnnyLunchbucket" is not able to access the database
"DatabaseB" under the current security context.
*/
EXEC [dbo].[InsertIntoTableWithTrigger]; -- SUCCESS!!!
REVERT;
SELECT SESSION_USER AS [User], ORIGINAL_LOGIN() AS [OriginalLogin];
SELECT * FROM [DatabaseB].[dbo].[TableWithTrigger];
SELECT * FROM [DatabaseB].[dbo].[TablePopulatedByTrigger];
-- 2 968DB092-C3DE-4E4B-92B9-E21CA551A5FA
-- 1 968DB092-C3DE-4E4B-92B9-E21CA551A5FA