sfilter动态加解密吐血总结

晕了好几天，总算把Ifs的动态加解密给闹明白了。
为了后来者不再晕，总结如下:

1.加密在SfWrite(IRP_MJ_WRITE)中，而不是完成例程，
解密在SfRead(IRP_MJ_READ)中，而不是完成例程，

3.只要处理IRP_NOCACHE|IRP_PAGING_IO|IRP_SYNCHRONOUS_PAGING_IO

2.加密简单过程:
a.得到Windows传下来的Buffer Address,
if (Irp->MdlAddress)
{
SysDataBuf = MmGetSystemAddressForMdlSafe(Irp->MdlAddress, NormalPagePriority);
}
else
{
SysDataBuf = Irp->UserBuffer;
}
b.保存明文SysDataBuf 在SysDataBufFirst

c.用你强大的算法加密SysDataBuf -->> MyBuf

d.把MyBuf Copy到 SysDataBuf，

e.IoCallDriver 把密文向下传，写入HardDisk。

f.恢复内存的明文 RtlCopyMemory(SysDataBuf,SysDataBufFirst, ulWriteLen);.

3.解密的大致过程:
a.IoCallDriver 读到密文
b，解密
c。IoCompleteRequest 搞定

我的开发环境:
IFS2600,SFilter的代码却是for XP SP1的

再仍一块砖头：
如何从IrpStackLocation中判断来自网络的文件访问？

//---------------------------------------------------
NTSTATUS status;

PACCESS_TOKEN pToken = NULL;
PTOKEN_SOURCE pTokenSrc = NULL ;
PSECURITY_SUBJECT_CONTEXT secSubCtx;


secSubCtx = &(IrpSp->Parameters.Create.SecurityContext->AccessState->SubjectSecurityContext);

if (secSubCtx->ClientToken != NULL || secSubCtx->PrimaryToken != NULL)
{
pToken = SeQuerySubjectContextToken(secSubCtx);
}

if (pToken == NULL)
{
//KdPrint(("SeQuerySubjectContextToken Errorn"));
return 0
}

//
// Get TokenSource Name If SourceName is "NtLmSsp" it was logged-in via Lanmanager,
// "User32" represents localy logged-in users.
//
__try
{

status = SeQueryInformationToken(pToken,TokenSource,&pTokenSrc);

if (NT_SUCCESS(status))
{
pTokenSrc->SourceName[TOKEN_SOURCE_LENGTH-1] = 0x00;

KdPrint(("Token Name :%s Len:%dn",pTokenSrc->SourceName,strlen(pTokenSrc->SourceName)));

if (_stricmp(pTokenSrc->SourceName,"NtLmSsp") == 0 )
{
KdPrint(("NetWork Access Token Findn"));
return 123
}

}
else
{
KdPrint(("SeQueryInformationToken Error:0x%xn",status));
}
}
__finally
{
ExFreePool(pTokenSrc);
}


return 0