PoolManager.c File Reference

The pool manager used in vmx root. More...

#include "pch.h"

Functions
BOOLEAN	PlmgrAllocateRequestNewAllocation (SIZE_T NumberOfBytes)
	Allocate global requesting variable.
VOID	PlmgrFreeRequestNewAllocation (VOID)
BOOLEAN	PoolManagerInitialize ()
	Initializes the pool manager.
VOID	PoolManagerUninitialize ()
	Uninitialize the pool manager (free the buffers, etc.)
BOOLEAN	PoolManagerFreePool (UINT64 AddressToFree)
	This function set a pool flag to be freed, and it will be freed on the next IOCTL when it's safe to remove.
VOID	PoolManagerShowPreAllocatedPools ()
	Shows list of pre-allocated pools available (used for debugging purposes)
UINT64	PoolManagerRequestPool (POOL_ALLOCATION_INTENTION Intention, BOOLEAN RequestNewPool, UINT32 Size)
	This function should be called from vmx-root in order to get a pool from the list.
BOOLEAN	PoolManagerAllocateAndAddToPoolTable (SIZE_T Size, UINT32 Count, POOL_ALLOCATION_INTENTION Intention)
	Allocate the new pools and add them to pool table.
BOOLEAN	PoolManagerCheckAndPerformAllocationAndDeallocation ()
	This function performs allocations from VMX non-root based on g_RequestNewAllocation.
BOOLEAN	PoolManagerRequestAllocation (SIZE_T Size, UINT32 Count, POOL_ALLOCATION_INTENTION Intention)
	Request to allocate new buffers.

Detailed Description

The pool manager used in vmx root.

Author

Sina Karvandi (sina@.nosp@m.hype.nosp@m.rdbg..nosp@m.org)

As we cannot allocate pools in vmx root, we need a pool manager to manage the pools

Version

0.1

Date

2020-04-11

Copyright

This project is released under the GNU Public License v3.

Function Documentation

PlmgrAllocateRequestNewAllocation()

BOOLEAN PlmgrAllocateRequestNewAllocation

(

SIZE_T

NumberOfBytes

)

Allocate global requesting variable.

Parameters

NumberOfBytes

Returns

{
    //
    // Allocate global requesting variable
    //
    g_RequestNewAllocation = PlatformMemAllocateZeroedNonPagedPool(NumberOfBytes);
 
    if (!g_RequestNewAllocation)
    {
        return FALSE;
    }
 
    return TRUE;
}

PlmgrFreeRequestNewAllocation()

VOID PlmgrFreeRequestNewAllocation

(

VOID

)

{
    PlatformMemFreePool(g_RequestNewAllocation);
    g_RequestNewAllocation = NULL;
}

PoolManagerAllocateAndAddToPoolTable()

BOOLEAN PoolManagerAllocateAndAddToPoolTable	(	SIZE_T	Size,
		UINT32	Count,
		POOL_ALLOCATION_INTENTION	Intention )

Allocate the new pools and add them to pool table.

This function doesn't need lock as it just calls once from PASSIVE_LEVEL

Parameters

Size	Size of each chunk
Count	Count of chunks
Intention	The Intention of the buffer (buffer tag)

Returns

BOOLEAN If the allocation was successful it returns true and if it was unsuccessful then it returns false

{
    for (size_t i = 0; i < Count; i++)
    {
        POOL_TABLE * SinglePool = NULL;
 
        SinglePool = PlatformMemAllocateZeroedNonPagedPool(sizeof(POOL_TABLE));
 
        if (!SinglePool)
        {
            LogError("Err, insufficient memory");
            return FALSE;
        }
 
        //
        // Allocate the buffer
        //
        SinglePool->Address = (UINT64)PlatformMemAllocateZeroedNonPagedPool(Size);
 
        if (!SinglePool->Address)
        {
            PlatformMemFreePool(SinglePool);
 
            LogError("Err, insufficient memory");
            return FALSE;
        }
 
        SinglePool->Intention     = Intention;
        SinglePool->IsBusy        = FALSE;
        SinglePool->ShouldBeFreed = FALSE;
        SinglePool->AlreadyFreed  = FALSE;
        SinglePool->Size          = Size;
 
        //
        // Add it to the list
        //
        InsertHeadList(&g_ListOfAllocatedPoolsHead, &(SinglePool->PoolsList));
    }
 
    return TRUE;
}

PoolManagerCheckAndPerformAllocationAndDeallocation()

BOOLEAN PoolManagerCheckAndPerformAllocationAndDeallocation

(

)

This function performs allocations from VMX non-root based on g_RequestNewAllocation.

Returns

BOOLEAN If the pool manager allocates buffer or there was no buffer to allocate then it returns true, if there was any error then it returns false

{
    BOOLEAN     Result   = TRUE;
    PLIST_ENTRY ListTemp = 0;
 
    //
    // let's make sure we're on vmx non-root and also we have new allocation
    //
    if (VmxGetCurrentExecutionMode() == TRUE)
    {
        //
        // allocation's can't be done from vmx root
        //
        return FALSE;
    }
 
    //
    // Make sure paging works properly
    //
    PAGED_CODE();
 
    //
    // Check for new allocation
    //
    if (g_IsNewRequestForAllocationReceived)
    {
        for (SIZE_T i = 0; i < MaximumRequestsQueueDepth; i++)
        {
            REQUEST_NEW_ALLOCATION * CurrentItem = &g_RequestNewAllocation[i];
 
            if (CurrentItem->Size != 0)
            {
                Result = PoolManagerAllocateAndAddToPoolTable(CurrentItem->Size,
                                                              CurrentItem->Count,
                                                              CurrentItem->Intention);
 
                //
                // Free the data for future use
                //
                CurrentItem->Count     = 0;
                CurrentItem->Intention = 0;
                CurrentItem->Size      = 0;
            }
        }
    }
 
    //
    // Check for deallocation
    //
    if (g_IsNewRequestForDeAllocation)
    {
        ListTemp = &g_ListOfAllocatedPoolsHead;
 
        SpinlockLock(&LockForReadingPool);
 
        while (&g_ListOfAllocatedPoolsHead != ListTemp->Flink)
        {
            ListTemp = ListTemp->Flink;
 
            //
            // Get the head of the record
            //
            PPOOL_TABLE PoolTable = (PPOOL_TABLE)CONTAINING_RECORD(ListTemp, POOL_TABLE, PoolsList);
 
            //
            // Check whether this pool should be freed or not and
            // also check whether it's already freed or not
            //
            if (PoolTable->ShouldBeFreed && !PoolTable->AlreadyFreed)
            {
                //
                // Set the flag to indicate that we freed
                //
                PoolTable->AlreadyFreed = TRUE;
 
                //
                // This item should be freed
                //
                PlatformMemFreePool((PVOID)PoolTable->Address);
 
                //
                // Now we should remove the entry from the g_ListOfAllocatedPoolsHead
                //
                RemoveEntryList(&PoolTable->PoolsList);
 
                //
                // Free the structure pool
                //
                PlatformMemFreePool(PoolTable);
            }
        }
 
        SpinlockUnlock(&LockForReadingPool);
    }
 
    //
    // All allocation and deallocation are performed
    //
    g_IsNewRequestForDeAllocation       = FALSE;
    g_IsNewRequestForAllocationReceived = FALSE;
 
    return Result;
}

PoolManagerFreePool()

BOOLEAN PoolManagerFreePool

(

UINT64

AddressToFree

)

This function set a pool flag to be freed, and it will be freed on the next IOCTL when it's safe to remove.

Parameters

AddressToFree

The pool address that was previously obtained from the pool manager

Returns

BOOLEAN If the address was already in the list of allocated pools by pool manager then it returns TRUE; otherwise, FALSE

{
    PLIST_ENTRY ListTemp = 0;
    BOOLEAN     Result   = FALSE;
    ListTemp             = &g_ListOfAllocatedPoolsHead;
 
    SpinlockLock(&LockForReadingPool);
 
    while (&g_ListOfAllocatedPoolsHead != ListTemp->Flink)
    {
        ListTemp = ListTemp->Flink;
 
        //
        // Get the head of the record
        //
        PPOOL_TABLE PoolTable = (PPOOL_TABLE)CONTAINING_RECORD(ListTemp, POOL_TABLE, PoolsList);
 
        if (PoolTable->Address == AddressToFree)
        {
            //
            // We found an entry that matched the detailed from
            // previously allocated pools
            //
            PoolTable->ShouldBeFreed = TRUE;
            Result                   = TRUE;
 
            g_IsNewRequestForDeAllocation = TRUE;
            break;
        }
    }
 
    SpinlockUnlock(&LockForReadingPool);
    return Result;
}

PoolManagerInitialize()

BOOLEAN PoolManagerInitialize

(

)

Initializes the pool manager.

Initializes the Pool Manager and pre-allocate some pools.

Returns

BOOLEAN

{
    //
    // Allocate global requesting variable
    //
    SIZE_T BufferSize = MaximumRequestsQueueDepth * sizeof(REQUEST_NEW_ALLOCATION);
    if (!PlmgrAllocateRequestNewAllocation(BufferSize))
    {
        LogError("Err, insufficient memory");
        return FALSE;
    }
 
    //
    // Initialize list head
    //
    InitializeListHead(&g_ListOfAllocatedPoolsHead);
 
    //
    // Nothing to deallocate
    //
    g_IsNewRequestForDeAllocation = FALSE;
 
    //
    // Initialized successfully
    //
    return TRUE;
}

PoolManagerRequestAllocation()

BOOLEAN PoolManagerRequestAllocation	(	SIZE_T	Size,
		UINT32	Count,
		POOL_ALLOCATION_INTENTION	Intention )

Request to allocate new buffers.

Parameters

Size	Request new buffer to allocate
Count	Count of chunks
Intention	The intention of chunks (buffer tag)

Returns

BOOLEAN If the request is save it returns true otherwise it returns false

{
    BOOLEAN FoundAPlace = FALSE;
 
    //
    // ******** We check to find a free place to store ********
    //
 
    SpinlockLock(&LockForRequestAllocation);
 
    for (SIZE_T i = 0; i < MaximumRequestsQueueDepth; i++)
    {
        REQUEST_NEW_ALLOCATION * CurrentItem = &g_RequestNewAllocation[i];
 
        if (CurrentItem->Size == 0)
        {
            CurrentItem->Count     = Count;
            CurrentItem->Intention = Intention;
            CurrentItem->Size      = Size;
 
            FoundAPlace = TRUE;
 
            break;
        }
    }
 
    if (!FoundAPlace)
    {
        SpinlockUnlock(&LockForRequestAllocation);
        return FALSE;
    }
 
    //
    // Signals to show that we have new allocations
    //
    g_IsNewRequestForAllocationReceived = TRUE;
 
    SpinlockUnlock(&LockForRequestAllocation);
    return TRUE;
}

PoolManagerRequestPool()

UINT64 PoolManagerRequestPool	(	POOL_ALLOCATION_INTENTION	Intention,
		BOOLEAN	RequestNewPool,
		UINT32	Size )

This function should be called from vmx-root in order to get a pool from the list.

If RequestNewPool is TRUE then Size is used, otherwise Size is useless Note : Most of the times this function called from vmx root but not all the time

Parameters

Intention	The intention why we need this pool for (buffer tag)
RequestNewPool	Create a request to allocate a new pool with the same size, next time that it's safe to allocate (this way we never ran out of pools for this "Intention")
Size	If the RequestNewPool is true the we should specify a size for the new pool

Returns

UINT64 Returns a pool address or returns null if there was an error

{
    UINT64 Address = 0;
 
    ScopedSpinlock(
        LockForReadingPool,
        LIST_FOR_EACH_LINK(g_ListOfAllocatedPoolsHead, POOL_TABLE, PoolsList, PoolTable) {
            if (PoolTable->Intention == Intention && PoolTable->IsBusy == FALSE)
            {
                PoolTable->IsBusy = TRUE;
                Address           = PoolTable->Address;
                break;
            }
        });
 
    //
    // Check if we need additional pools e.g another pool or the pool
    // will be available for the next use blah blah
    //
    if (RequestNewPool)
    {
        PoolManagerRequestAllocation(Size, 1, Intention);
    }
 
    //
    // return Address might be null indicating there is no valid pools
    //
    return Address;
}

PoolManagerShowPreAllocatedPools()

VOID PoolManagerShowPreAllocatedPools

(

)

Shows list of pre-allocated pools available (used for debugging purposes)

Returns

VOID

{
    PLIST_ENTRY ListTemp = 0;
    ListTemp             = &g_ListOfAllocatedPoolsHead;
 
    while (&g_ListOfAllocatedPoolsHead != ListTemp->Flink)
    {
        ListTemp = ListTemp->Flink;
 
        //
        // Get the head of the record
        //
        PPOOL_TABLE PoolTable = (PPOOL_TABLE)CONTAINING_RECORD(ListTemp, POOL_TABLE, PoolsList);
 
        LogInfo("Pool details, Pool intention: %x | Pool address: %llx | Pool state: %s | Should be freed: %s | Already freed: %s\n",
                PoolTable->Intention,
                PoolTable->Address,
                PoolTable->IsBusy ? "used" : "free",
                PoolTable->ShouldBeFreed ? "true" : "false",
                PoolTable->AlreadyFreed ? "true" : "false");
    }
}

PoolManagerUninitialize()

VOID PoolManagerUninitialize

(

)

Uninitialize the pool manager (free the buffers, etc.)

De-allocate all the allocated pools.

Returns

VOID

{
    PLIST_ENTRY ListTemp = 0;
    ListTemp             = &g_ListOfAllocatedPoolsHead;
 
    SpinlockLock(&LockForReadingPool);
 
    while (&g_ListOfAllocatedPoolsHead != ListTemp->Flink)
    {
        ListTemp = ListTemp->Flink;
 
        //
        // Get the head of the record
        //
        PPOOL_TABLE PoolTable = (PPOOL_TABLE)CONTAINING_RECORD(ListTemp, POOL_TABLE, PoolsList);
 
        //
        // Free the alloocated buffer (if not already changed)
        //
        if (!PoolTable->AlreadyFreed)
        {
            PlatformMemFreePool((PVOID)PoolTable->Address);
        }
 
        //
        // Unlink the PoolTable
        //
        RemoveEntryList(&PoolTable->PoolsList);
 
        //
        // Free the record itself
        //
        PlatformMemFreePool(PoolTable);
    }
 
    SpinlockUnlock(&LockForReadingPool);
 
    PlmgrFreeRequestNewAllocation();
}