Joey recently introduced a Memory-Deny-Write-Executable (MDWE) prctl which tags current with a flag that prevents pages that were previously not executable from becoming executable. This tag always gets inherited by children tasks. (it's in MMF_INIT_MASK) At Google, we've been using a somewhat similar downstream patch for a few years now. To make the adoption of this feature easier, we've had it support a mode in which the W^X flag does not propagate to children. For example, this is handy if a C process which wants W^X protection suspects it could start children processes that would use a JIT. I'd like to align our features with the upstream prctl. This series proposes a new NO_INHERIT flag to the MDWE prctl to make this kind of adoption easier. It sets a different flag in current that is not in MMF_INIT_MASK and which does not propagate. As part of looking into MDWE, I also fixed a couple of things in the MDWE test. Florent Revest (4): kselftest: vm: Fix tabs/spaces inconsistency in the mdwe test kselftest: vm: Fix mdwe's mmap_FIXED test case mm: Add a NO_INHERIT flag to the PR_SET_MDWE prctl kselftest: vm: Add tests for no-inherit memory-deny-write-execute include/linux/mman.h | 8 +- include/linux/sched/coredump.h | 1 + include/uapi/linux/prctl.h | 1 + kernel/sys.c | 29 +++++-- tools/include/uapi/linux/prctl.h | 1 + tools/testing/selftests/mm/mdwe_test.c | 110 +++++++++++++++++++++---- 6 files changed, 128 insertions(+), 22 deletions(-) -- 2.40.1.495.gc816e09b53d-goog
