SpInitLsaModeContextFn callback function (ntsecpkg.h)

Article
10/13/2021

The SpInitLsaModeContext function is the client dispatch function used to establish a security context between a server and client.

The SpInitLsaModeContext function is called when the client calls the InitializeSecurityContext (General) function of the Security Support Provider Interface.

Syntax

SpInitLsaModeContextFn Spinitlsamodecontextfn;

NTSTATUS Spinitlsamodecontextfn(
  [in]  LSA_SEC_HANDLE CredentialHandle,
  [in]  LSA_SEC_HANDLE ContextHandle,
  [in]  PUNICODE_STRING TargetName,
  [in]  ULONG ContextRequirements,
  [in]  ULONG TargetDataRep,
  [in]  PSecBufferDesc InputBuffers,
  [out] PLSA_SEC_HANDLE NewContextHandle,
  [out] PSecBufferDesc OutputBuffers,
  [out] PULONG ContextAttributes,
  [out] PTimeStamp ExpirationTime,
  [out] PBOOLEAN MappedContext,
  [out] PSecBuffer ContextData
)
{...}

Parameters

[in] CredentialHandle

Optional. Handle to the credentials to use for the context. CredentialHandle can be NULL if the ContextHandle parameter is not NULL.

[in] ContextHandle

Optional. Handle to the context to use as the basis for this context. ContextHandle can be NULL if the CredentialHandle parameter is not NULL.

[in] TargetName

Optional. Pointer to a UNICODE_STRING containing the name of the target of the context. The content of TargetName is package-specific and is not interpreted by the LSA.

[in] ContextRequirements

Flags indicating the context attributes required by the client. The actual context attributes are returned in the ContextAttributes parameter.

The following table lists the valid values.

Value	Meaning
ISC_REQ_DELEGATE	The server is allowed to impersonate the client.
ISC_REQ_MUTUAL_AUTH	Both the client and the server are required to prove their identity.
ISC_REQ_REPLAY_DETECT	The security context will support the detection of replayed packets.
ISC_REQ_SEQUENCE_DETECT	The security context will support the detection of out-of-order messages.
ISC_REQ_USE_SESSION_KEY	A new session key must be negotiated.
ISC_REQ_PROMPT_FOR_CREDS	If the client is an interactive user, the package must, if possible, prompt the user for the appropriate credentials.
ISC_REQ_USE_SUPPLIED_CREDS	The input buffer contains package-specific credential information which should be used to authenticate the connection.
ISC_REQ_ALLOCATE_MEMORY	The package must allocate memory. The caller must eventually call the FreeContextBuffer function to free memory allocated by the package.
ISC_REQ_USE_DCE_STYLE	The caller expects a three-leg mutual authentication transaction.
ISC_REQ_DATAGRAM	A datagram-type communications channel should be used. For more information, see Datagram Contexts.
ISC_REQ_CONNECTION	A connection-type communications channel should be used. For more information see Connection-Oriented Contexts.
ISC_REQ_EXTENDED_ERROR	If the context fails, generate an error reply message to send back to the client.
ISC_REQ_STREAM	A stream-type communications channel should be used. For more information, see Stream Contexts.
ISC_REQ_INTEGRITY	Buffer integrity is verified; however, replayed and out-of-sequence messages will not be detected.

[in] TargetDataRep

Flag indicating the data representation, such as byte ordering, on the target. Contains SECURITY_NATIVE_DREP or SECURITY_NETWORK_DREP.

[in] InputBuffers

Pointer to a SecBufferDesc structure containing the previous reply message from the server. The first time this function is called the InputBuffers parameter is NULL.

[out] NewContextHandle

Pointer that receives a handle to the new security context. When you have finished using the security context, release the handle by calling the SpDeleteContext function.

[out] OutputBuffers

Pointer to a SecBufferDesc structure containing the security token to pass back to the server.

[out] ContextAttributes

Pointer to flags specifying the attributes of the new context. The client requests a set of attributes using the ContextRequirements parameter. If the ContextRequirements flags do not match the ContextAttributes flags, the client must decide whether to continue or terminate. For a complete list of the valid flags, see Context Requirements.

[out] ExpirationTime

Pointer to a TimeStamp that receives the expiration time for the new context.

[out] MappedContext

Pointer to a Boolean value. Set MappedContext to TRUE if the security package implements the user-mode SSP/AP functions.

[out] ContextData

Pointer to a SecBuffer structure that receives the data to copy when creating a user-mode security context. Allocate memory for ContextData using the AllocateLsaHeap function. The LSA will free the memory.

Return value

If the function succeeds and no more processing is required, return STATUS_SUCCESS. If processing is not complete, the function should return SEC_I_CONTINUE_NEEDED. When this value is returned, the caller must call the InitializeSecurityContext (General) function again.

If the function fails to create the security context for any other reason, it should return an NTSTATUS code indicating the reason it failed.

Remarks

The SpAcceptLsaModeContext function is the server-side function for creating a context.

SSP/APs must implement the SpInitLsaModeContext function; however, the actual name given to the implementation is up to the developer.

A pointer to the SpInitLsaModeContext function is available in the SECPKG_FUNCTION_TABLE structure received from the SpLsaModeInitialize function.

Requirements

Requirement	Value
Minimum supported client	Windows XP [desktop apps only]
Minimum supported server	Windows Server 2003 [desktop apps only]
Target Platform	Windows
Header	ntsecpkg.h