Improve WFP filter-delete mock fidelity and add delete fault injection - #317
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The FWP user-mode mock diverged from real WFP filter-delete behavior: - The delete notification (FWPS_CALLOUT_NOTIFY_DELETE_FILTER) was raised with filterId = 0, so a callout that identifies the deleted filter by id could not match it. - remove_fwpm_filter asserted the callout was still registered and always raised the delete notification, whereas real WFP raises no delete notification once the callout function has been unregistered. Changes: - Set fwps_filter.filterId on the add and delete notifications. - Raise the delete notification only when the callout is still registered. - Add test-only fault injection (usersim_fwp_set_filter_delete_failure_count) plus usersim_fwp_get_fwpm_filter_count and usersim_fwp_clear_fwpm_filters to simulate and inspect a filter whose delete fails without removing the filter or notifying. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: c5be9327-3fe0-4580-b5c1-17b6c052bbb2
saxena-anurag
approved these changes
Aug 1, 2026
Clarify the comments around usersim_fwp_set_filter_delete_failure_count per review feedback: the public declaration in fwp_test.h now describes what the hook does, how it differs from the generic cxplat fault-injection harness (deterministic, opt-in, independent of cxplat_fault_injection_is_enabled()), and how to use it. The injection site in FwpmFilterDeleteById0 and the engine helper in fwp_um.h are reduced to short notes that cross-reference it. Comments only; no behavior change. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 1a991e01-4799-44d5-8290-68a48c363260
saxena-anurag
approved these changes
Aug 3, 2026
mikeagun
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Aug 3, 2026
microsoft/usersim#317 (the WFP filter-delete mock fidelity improvements and deterministic delete fault-injection hooks used by the netebpfext unit tests) has merged. Restore the external/usersim submodule URL to microsoft/usersim and advance the gitlink to the merged commit, replacing the temporary bump that pointed at the fork branch. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 1a991e01-4799-44d5-8290-68a48c363260
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Description
The FWP user-mode mock diverged from real WFP filter-delete behavior in two ways that matter to callouts which track per-filter state:
FWPS_CALLOUT_NOTIFY_DELETE_FILTER) was raised withfilterId = 0, so a callout that identifies the deleted filter by id could not match it.remove_fwpm_filterasserted the callout was still registered and always raised the delete notification, whereas real WFP raises no delete notification once the callout function has been unregistered (e.g., during driver unload).This change makes the mock faithful and adds a small test-only fault-injection surface so extensions can exercise their filter-delete-failure recovery paths.
Changes
fwps_filter.filterIdon the add and delete notifications.usersim_fwp_set_filter_delete_failure_count(fail the next NFwpmFilterDeleteByIdcalls without removing the filter or notifying),usersim_fwp_get_fwpm_filter_count, andusersim_fwp_clear_fwpm_filters.Testing
Consumed by the ebpf-for-windows netebpfext WFP filter-teardown regression tests. Existing usersim tests unaffected.