Messages in this thread Patch in this message | | | From | Peter Xu <> | Subject | [PATCH 4/6] mm/userfaultfd: Fail uffd-wp registeration if not supported | Date | Wed, 28 Apr 2021 18:50:28 -0400 |
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We should fail uffd-wp registration immediately if the arch does not even have CONFIG_HAVE_ARCH_USERFAULTFD_WP defined. That'll block also relevant ioctls on e.g. UFFDIO_WRITEPROTECT because that'll check against VM_UFFD_WP, which can only be applied with a success registration.
Remove the WP feature bit too for those archs when handling UFFDIO_API ioctl.
Signed-off-by: Peter Xu <peterx@redhat.com> --- fs/userfaultfd.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 14f92285d04f8..5dd78238cc156 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -1304,8 +1304,12 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, vm_flags = 0; if (uffdio_register.mode & UFFDIO_REGISTER_MODE_MISSING) vm_flags |= VM_UFFD_MISSING; - if (uffdio_register.mode & UFFDIO_REGISTER_MODE_WP) + if (uffdio_register.mode & UFFDIO_REGISTER_MODE_WP) { +#ifndef CONFIG_HAVE_ARCH_USERFAULTFD_WP + goto out; +#endif vm_flags |= VM_UFFD_WP; + } if (uffdio_register.mode & UFFDIO_REGISTER_MODE_MINOR) { #ifndef CONFIG_HAVE_ARCH_USERFAULTFD_MINOR goto out; @@ -1942,6 +1946,9 @@ static int userfaultfd_api(struct userfaultfd_ctx *ctx, uffdio_api.features = UFFD_API_FEATURES; #ifndef CONFIG_HAVE_ARCH_USERFAULTFD_MINOR uffdio_api.features &= ~UFFD_FEATURE_MINOR_HUGETLBFS; +#endif +#ifndef CONFIG_HAVE_ARCH_USERFAULTFD_WP + uffdio_api.features &= ~UFFD_FEATURE_PAGEFAULT_FLAG_WP; #endif uffdio_api.ioctls = UFFD_API_IOCTLS; ret = -EFAULT; -- 2.26.2
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