DuplicateTokenEx function (securitybaseapi.h)

The DuplicateTokenEx function creates a new access token that duplicates an existing token. This function can create either a primary token or an impersonation token.

Syntax

BOOL DuplicateTokenEx(
  [in]           HANDLE                       hExistingToken,
  [in]           DWORD                        dwDesiredAccess,
  [in, optional] LPSECURITY_ATTRIBUTES        lpTokenAttributes,
  [in]           SECURITY_IMPERSONATION_LEVEL ImpersonationLevel,
  [in]           TOKEN_TYPE                   TokenType,
  [out]          PHANDLE                      phNewToken
);

Parameters

[in] hExistingToken

A handle to an access token opened with TOKEN_DUPLICATE access.

[in] dwDesiredAccess

Specifies the requested access rights for the new token. The DuplicateTokenEx function compares the requested access rights with the existing token's discretionary access control list (DACL) to determine which rights are granted or denied. To request the same access rights as the existing token, specify zero. To request all access rights that are valid for the caller, specify MAXIMUM_ALLOWED.

For a list of access rights for access tokens, see Access Rights for Access-Token Objects.

[in, optional] lpTokenAttributes

A pointer to a SECURITY_ATTRIBUTES structure that specifies a security descriptor for the new token and determines whether child processes can inherit the token. If lpTokenAttributes is NULL, the token gets a default security descriptor and the handle cannot be inherited. If the security descriptor contains a system access control list (SACL), the token gets ACCESS_SYSTEM_SECURITY access right, even if it was not requested in dwDesiredAccess.

To set the owner in the security descriptor for the new token, the caller's process token must have the SE_RESTORE_NAME privilege set.

[in] ImpersonationLevel

Specifies a value from the SECURITY_IMPERSONATION_LEVEL enumeration that indicates the impersonation level of the new token.

[in] TokenType

Specifies one of the following values from the TOKEN_TYPE enumeration.

[out] phNewToken

A pointer to a HANDLE variable that receives the new token.

When you have finished using the new token, call the CloseHandle function to close the token handle.

Return value

If the function succeeds, the function returns a nonzero value.

If the function fails, it returns zero. To get extended error information, call GetLastError.

Remarks

The DuplicateTokenEx function allows you to create a primary token that you can use in the CreateProcessAsUser function. This allows a server application that is impersonating a client to create a process that has the security context of the client. Note that the DuplicateToken function can create only impersonation tokens, which are not valid for CreateProcessAsUser.

The following is a typical scenario for using DuplicateTokenEx to create a primary token. A server application creates a thread that calls one of the impersonation functions, such as ImpersonateNamedPipeClient, to impersonate a client. The impersonating thread then calls the OpenThreadToken function to get its own token, which is an impersonation token that has the security context of the client. The thread specifies this impersonation token in a call to DuplicateTokenEx, specifying the TokenPrimary flag. The DuplicateTokenEx function creates a primary token that has the security context of the client.

Requirements

See also

Access Control

Basic Access Control Functions

CloseHandle

CreateProcessAsUser

DdeImpersonateClient

DuplicateToken

ImpersonateNamedPipeClient

OpenThreadToken

RevertToSelf

RpcImpersonateClient

SECURITY_ATTRIBUTES

SECURITY_IMPERSONATION_LEVEL