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Message-ID: <8fde3b26-c37a-4ec3-9cf8-2663347081f2@lucifer.local>
Date: Thu, 17 Oct 2024 09:35:15 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: jeffxu@...omium.org
Cc: akpm@...ux-foundation.org, keescook@...omium.org,
torvalds@...ux-foundation.org, usama.anjum@...labora.com,
corbet@....net, Liam.Howlett@...cle.com, jeffxu@...gle.com,
jorgelo@...omium.org, groeck@...omium.org,
linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
linux-mm@...ck.org, jannh@...gle.com, sroettger@...gle.com,
pedro.falcato@...il.com, linux-hardening@...r.kernel.org,
willy@...radead.org, gregkh@...uxfoundation.org, deraadt@...nbsd.org,
surenb@...gle.com, merimus@...gle.com, rdunlap@...radead.org,
stable@...r.kernel.org
Subject: Re: [PATCH v1 2/2] selftest/mseal: Add tests for madvise fixes
On Thu, Oct 17, 2024 at 12:51:05AM +0000, jeffxu@...omium.org wrote:
> From: Jeff Xu <jeffxu@...omium.org>
>
> Testcase for "Two fixes for madvise(MADV_DONTNEED) when sealed"
>
> test_seal_madvise_prot_none
> shall not block when mapping is PROT_NONE
>
> test_madvise_filebacked_writable
> shall not block writeable private filebacked mapping.
>
> test_madvise_filebacked_was_writable - shall block.
> shall block read-only private filebacked mapping which
> was previously writable.
>
> Fixes: 8be7258aad44 ("mseal: add mseal syscall")
> Cc: <stable@...r.kernel.org> # 6.11.y: 67203f3f2a63: selftests/mm: add mseal test for no-discard madvise
> Cc: <stable@...r.kernel.org> # 6.11.y: f28bdd1b17ec: selftests/mm: add more mseal traversal tests
> Cc: <stable@...r.kernel.org> # 6.11.y
> Signed-off-by: Jeff Xu <jeffxu@...omium.org>
> ---
> tools/testing/selftests/mm/mseal_test.c | 118 +++++++++++++++++++++++-
> 1 file changed, 116 insertions(+), 2 deletions(-)
>
> diff --git a/tools/testing/selftests/mm/mseal_test.c b/tools/testing/selftests/mm/mseal_test.c
> index 01675c412b2a..fa74dbe4a684 100644
> --- a/tools/testing/selftests/mm/mseal_test.c
> +++ b/tools/testing/selftests/mm/mseal_test.c
> @@ -1728,7 +1728,7 @@ static void test_seal_discard_ro_anon_on_filebacked(bool seal)
> FAIL_TEST_IF_FALSE(!ret);
> }
>
> - /* sealing doesn't apply for file backed mapping. */
> + /* read-only private file-backed mapping, allow always */
> ret = sys_madvise(ptr, size, MADV_DONTNEED);
> FAIL_TEST_IF_FALSE(!ret);
>
> @@ -1864,6 +1864,111 @@ static void test_seal_madvise_nodiscard(bool seal)
> REPORT_TEST_PASS();
> }
>
Again you're doing things in these tests that have come up again and agin in
review, and so at some point as a reviewer you just have to stop until the
review-ee starts listening.
Either provide an utterly profound justification for:
FAIL_TEST_IF_FALSE(<negation>)
Or stop doing.
Either provide an utterly profound justification for:
(void *)-1 vs. MAP_FAILED
Or stop doing it.
I simply won't review/accept your test code until you do.
Thanks.
> +static void test_seal_madvise_prot_none(bool seal)
> +{
> + void *ptr;
> + unsigned long page_size = getpagesize();
> + unsigned long size = 4 * page_size;
> + int ret;
> +
> + setup_single_address(size, &ptr);
> + FAIL_TEST_IF_FALSE(ptr != (void *)-1);
> +
> + ret = sys_mprotect(ptr + page_size, page_size, PROT_NONE);
> + FAIL_TEST_IF_FALSE(!ret);
> +
> + if (seal) {
> + ret = seal_single_address(ptr + page_size, page_size);
> + FAIL_TEST_IF_FALSE(!ret);
> + }
> +
> + /* madvise(DONTNEED) should pass on PROT_NONE sealed VMA */
> + ret = sys_madvise(ptr + page_size, page_size, MADV_DONTNEED);
> + FAIL_TEST_IF_FALSE(!ret);
> +
> + REPORT_TEST_PASS();
> +}
> +
> +static void test_madvise_filebacked_writable(bool seal)
> +{
> + void *ptr;
> + unsigned long page_size = getpagesize();
> + unsigned long size = 4 * page_size;
> + int ret;
> + int fd;
> + unsigned long mapflags = MAP_PRIVATE;
> +
> + fd = memfd_create("test", 0);
> + FAIL_TEST_IF_FALSE(fd > 0);
> +
> + ret = fallocate(fd, 0, 0, size);
> + FAIL_TEST_IF_FALSE(!ret);
> +
> + ptr = mmap(NULL, size, PROT_READ|PROT_WRITE, mapflags, fd, 0);
> + FAIL_TEST_IF_FALSE(ptr != MAP_FAILED);
> +
> + if (seal) {
> + ret = sys_mseal(ptr, size);
> + FAIL_TEST_IF_FALSE(!ret);
> + }
> +
> + /* sealing doesn't apply for writeable file-backed mapping. */
> + ret = sys_madvise(ptr, size, MADV_DONTNEED);
> + FAIL_TEST_IF_FALSE(!ret);
> +
> + ret = sys_munmap(ptr, size);
> + if (seal)
> + FAIL_TEST_IF_FALSE(ret < 0);
> + else
> + FAIL_TEST_IF_FALSE(!ret);
> + close(fd);
> +
> + REPORT_TEST_PASS();
> +}
> +
> +static void test_madvise_filebacked_was_writable(bool seal)
> +{
> + void *ptr;
> + unsigned long page_size = getpagesize();
> + unsigned long size = 4 * page_size;
> + int ret;
> + int fd;
> + unsigned long mapflags = MAP_PRIVATE;
> +
> + fd = memfd_create("test", 0);
> + FAIL_TEST_IF_FALSE(fd > 0);
> +
> + ret = fallocate(fd, 0, 0, size);
> + FAIL_TEST_IF_FALSE(!ret);
> +
> + ptr = mmap(NULL, size, PROT_READ|PROT_WRITE, mapflags, fd, 0);
> + FAIL_TEST_IF_FALSE(ptr != MAP_FAILED);
> +
> + ret = sys_mprotect(ptr, size, PROT_READ);
> + FAIL_TEST_IF_FALSE(!ret);
> +
> + if (seal) {
> + ret = sys_mseal(ptr, size);
> + FAIL_TEST_IF_FALSE(!ret);
> + }
> +
> + /* read-only file-backed mapping, was writable. */
> + ret = sys_madvise(ptr, size, MADV_DONTNEED);
> + if (seal)
> + FAIL_TEST_IF_FALSE(ret < 0);
> + else
> + FAIL_TEST_IF_FALSE(!ret);
> +
> + ret = sys_munmap(ptr, size);
> + if (seal)
> + FAIL_TEST_IF_FALSE(ret < 0);
> + else
> + FAIL_TEST_IF_FALSE(!ret);
> + close(fd);
> +
> + REPORT_TEST_PASS();
> +}
> +
> int main(int argc, char **argv)
> {
> bool test_seal = seal_support();
> @@ -1876,7 +1981,7 @@ int main(int argc, char **argv)
> if (!pkey_supported())
> ksft_print_msg("PKEY not supported\n");
>
> - ksft_set_plan(88);
> + ksft_set_plan(94);
>
> test_seal_addseal();
> test_seal_unmapped_start();
> @@ -1985,5 +2090,14 @@ int main(int argc, char **argv)
> test_seal_discard_ro_anon_on_pkey(false);
> test_seal_discard_ro_anon_on_pkey(true);
>
> + test_seal_madvise_prot_none(false);
> + test_seal_madvise_prot_none(true);
> +
> + test_madvise_filebacked_writable(false);
> + test_madvise_filebacked_writable(true);
> +
> + test_madvise_filebacked_was_writable(false);
> + test_madvise_filebacked_was_writable(true);
> +
> ksft_finished();
> }
> --
> 2.47.0.rc1.288.g06298d1525-goog
>
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