This quick check based on bits and operation is for 2^ based
sector sizes (most of the cases) and will perform faster than
the modulo operation which is still used in fallback in case
the sector size wouldn't be a power of 2.
IopCloseFile can be called by IopDeleteFile. In that situation, it
doesn't set any process as first parameter. Furthermore, we are in a
situation where it's not required to lock the file object (see the
assert before the call).
- SeIsTokenChild(): Correctly check whether a caller-provided token
is a child from the current process' primary token by looking at
its ParentTokenId member.
- Add a SeIsTokenSibling() helper to determine whether a caller-provided
token and the current process' primary token are siblings, by comparing
their ParentTokenId's and AuthenticationId's.
NOTE: Children tokens are created through CreateRestrictedToken();
sibling tokens are created through DuplicateToken() (amongst others).
See slide 49 of https://www.slideshare.net/Shakacon/social-engineering-the-windows-kernel-by-james-forshaw
or https://googleprojectzero.blogspot.com/2016/01/raising-dead.html
for some details.
This could be triggered when attempting to read/write to really big
files. It was causing an attempt to read 0 bytes in Cc, leading to
asserts failure in the kernel (and corrupted file).
CORE-15067
Currently, our CcMapData() behavior (same goes for CcPinRead()) is broken
and is the total opposite of what Windows kernel does. By default, the later
will let you map a view in memory without even attempting to bring its
data in memory. On first access, there will be a fault and memory will
be read from the hardware and brought to memory. If you want to force read
on mapping/pinning, you have to set the MAP_NO_READ (or PIN_NO_READ) flag
where kernel will fault on your behalf (hence the need for MAP_WAIT/PIN_WAIT).
On ReactOS, by default, on mapping (and thus pinning), we will force a view
read so that data is in memory. The way our cache memory is managed at the
moment seems not to allow to fault on invalid access and if we don't force
read, the memory content will just be zeroed.
So trying to match Windows behavior, by default, now CcMapData() will enforce
the MAP_NO_READ flag and warn once about this behavior change.
It's based on the code that was in CcPinRead() implementation. This
made no sense to have CcPinMappedData() doing nothing while implementing
everything in CcPinRead(). Indeed, drivers (starting with MS drivers)
can map data first and pin it afterwards with CcPinMappedData(). It was
leading to incorrect behavior with our previous noop implementation.
Short: The code was suffering from an off-by-one bug (inconsistency between inclusive end exclusive end address), which could lead to freeing one page above the initialization code. This led to freeing part of the kernel import section on x64. Now it is consistently using the aligned/exclusive end address.
Long:
* Initialization sections are freed both for the boot loaded images as well as for drivers that are loaded later. Obviously the second mechanism needs to be able to run at any time, so it is not initialization code itself. For some reason someone decided though, it would be a smart idea to implement the code twice, once for the boot loaded images, once for drivers and concluding that the former was initialization code itself and had to be freed.
* Since freeing the code that frees the initialization sections, while it is doing that is not possible, it uses a "smart trick", initially skipping that range, returning its start and end to the caller and have the caller free it afterwards.
* The code was using the end address in an inconsistent way, partly aligning it to the start of the following section, sometimes pointing to the last byte that should be freed. The function that freed each chunk was assuming the latter (i.e. that the end was included in the range) and thus freed the page that contained the end address. The end address for the range that was returned to the caller was aligned to the start of the next section, and the caller used it to free the range including the following page. On x64 this was the start of the import section of ntoskrnl. How that worked on x86 I don't even want to know.
