Guard Pages Mechanism #2377
Guard Pages Mechanism #2377
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Status: Awaiting review
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Have you thought into adding an integration test for this? Would be nice to have a mechanism to verify how this protects against a malicious guest kernel driver. |
There are a couple of unit tests in this PR that simulate the effect of what a malicious guest kernel would do. @berciuliviu you can further improve them by also performing read/writes that start from a valid range and overlap the guard pages. |
Understood. I will add such a test that will mimic the behaviour of test_create_guest_memory_guarded, but will instead do as you suggested, to perform operations until overlapping with the guard pages. |
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This patch implements a page guarding mechanism. It will be applied at guest memory creation step and at snapshot memory restore. Signed-off-by: berciuliviu <[email protected]>
Increase Pytest coverage for Page Guarding Mechanism. Signed-off-by: berciuliviu <[email protected]>
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@sandreim PTAL! |
| @@ -41,6 +43,9 @@ pub use vm_memory_upstream::mmap::{check_file_offset, Error}; | |||
| // The maximum number of bytes that can be read/written at a time. | |||
| static MAX_ACCESS_CHUNK: usize = 4096; | |||
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| // The number of guard pages per region is a multiple of 2. | |||
| const GUARD_NUMBER: usize = 2; | |||
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nit: I would name this to something like GUARD_PAGE_COUNT that is in line with what this constant does. GUARD_NUMBER may be misleading IMO.
Reason for This PR
This PR fixes the following issue.
Description of Changes
A guard page mechanism is implemented for guest memory creation and restore from Snapshot. Every memory region in the before mentioned cases will be surrounded by a left/right border, with the dimension of a system's PAGE_SIZE.
Rust unittests are also implemented.
rust-vmm.License Acceptance
By submitting this pull request, I confirm that my contribution is made under
the terms of the Apache 2.0 license.
PR Checklist
[Author TODO: Meet these criteria.][Reviewer TODO: Verify that these criteria are met. Request changes if not]git commit -s).unsafecode is properly documented.firecracker/swagger.yaml.CHANGELOG.md.