From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oa1-f45.google.com (mail-oa1-f45.google.com [209.85.160.45]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C424314AD38 for ; Fri, 30 Aug 2024 23:57:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.45 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725062263; cv=none; b=qdXFe1yBhMN4qDRgJq3SbdSarpd7B8L5GdzalONHc877SOxGksD0HSfdTGLu3z7RNEEukfcyyqDtQmS76YZ+uYgGamDxrox8OgtMldln7XPO79y6bGEyATN8xMEzHX1odrHV9U9nt6n7uWvitmOMfE8z/h1g1ie+l7SQoH/fWl0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725062263; c=relaxed/simple; bh=dCKdUGjicATV4rkdkvomgbNd8TuLGBpl3gUg9RLVAPQ=; h=MIME-Version:References:In-Reply-To:From:Date:Message-ID:Subject: To:Cc:Content-Type; b=jDSbN7tajALij/odVPnRfS6jgUF4lBdotnx6on2UGx6ysJ0/UkRlx2I4v1rWAH2szgBFmo9ppheaEFwG13Xgm3aTe6PIqWthIxOVl/Ma6YfReiRflESQ/xMB1OxMNyQ4RwMCZKZy+Lyzg7Oj7pmlL5EIe746LxDdB/mcf5RrXsU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org; spf=pass smtp.mailfrom=chromium.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b=VlniHyU4; arc=none smtp.client-ip=209.85.160.45 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=chromium.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="VlniHyU4" Received: by mail-oa1-f45.google.com with SMTP id 586e51a60fabf-2611dcc3941so154695fac.3 for ; Fri, 30 Aug 2024 16:57:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1725062259; x=1725667059; darn=vger.kernel.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=nvEfYKOVVxE8dkrUColYKOziuScNHjuMeSwgzin4M+4=; b=VlniHyU4CHxwQmk3shD/r56HkwIAE2YgZgtQOmxCfxilQhmKyJk1V7daHLKgel4SR6 V/i6vQ9KkKScAA7cdv/VW2k5nbY/Sx/ORT9Xo1QKYRA3QS/qg6NIhX2N2qcB/plafc1T uNBkf4eLvRLnwI7Komr9wn2q/PXRsv94zQpDg= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1725062259; x=1725667059; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=nvEfYKOVVxE8dkrUColYKOziuScNHjuMeSwgzin4M+4=; b=PmJVnq0eS6Io4E9blqfKp9Wp9EGTADrgHcfhkMDYoWGelBkmQ4Rp0dawxndgmQRvCM t13QQhTiVIIpcnq/U1WqH8hVivZIY/eJq4WVy8uWpqjnXCTya7+7DfALxToq73CQQmaV ZTWHQHS/bMSXXVrkt9Gf0jYVuqjeZW9HEsWzC0ETHITSma2tYr+bLVAqdv0ZGOoAbvuL Cwy0dlGECZaGr+FLzgIjhn04oOk1YXugeHNQD+10JylNaMNlXS3zbg/Oczsr0khVQFQl 4L1pKOcurWynsYZdCykmauM5vZq8J42fTmWCCfgmF9QdF+F5ybXHXABaPghEbkjboRJb 8zdg== X-Forwarded-Encrypted: i=1; AJvYcCVvA0+YpRA3BIVtPQUxxArxXmXj66GcpnvkG/D/B73AtAo9lrePveV4glMpmqz0SNOF3qdeaJzun4WUMNI=@vger.kernel.org X-Gm-Message-State: AOJu0Yz9cvo4Up6QBzpUGDZjsLLyKucm9EEbrzj3gKaskCmoXa1Nlkae NcWJ5EtiODLvuoJfSxMKybWbRj4x5WoBg8fsFlgCOUeRBqfqxy3oRMheRcZ/T5nfDcEgQfi41IZ AVDOrcQC9Mnd+77Oam9QuNzdcIiahML9+Dptj X-Google-Smtp-Source: AGHT+IGjMwvg2UrGjfLtNCLSGM6nxH1ui5UjTCg13Enlj4QaUBaQ5TbLUJTqV1S+O33PHEODxv9SrU2l5S/YzS1NHlE= X-Received: by 2002:a05:6870:218c:b0:277:6b90:1915 with SMTP id 586e51a60fabf-277b0e4fcc6mr2021449fac.9.1725062258617; Fri, 30 Aug 2024 16:57:38 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20240830180237.1220027-1-jeffxu@chromium.org> <20240830180237.1220027-5-jeffxu@chromium.org> In-Reply-To: From: Jeff Xu Date: Fri, 30 Aug 2024 16:57:26 -0700 Message-ID: Subject: Re: [PATCH v3 4/5] selftests/mseal: add more tests for mmap To: Lorenzo Stoakes Cc: akpm@linux-foundation.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org, pedro.falcato@gmail.com, willy@infradead.org, broonie@kernel.org, vbabka@suse.cz, Liam.Howlett@oracle.com, rientjes@google.com, keescook@chromium.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Fri, Aug 30, 2024 at 12:23=E2=80=AFPM Lorenzo Stoakes wrote: > > On Fri, Aug 30, 2024 at 07:43:12PM GMT, Lorenzo Stoakes wrote: > > On Fri, Aug 30, 2024 at 06:02:36PM GMT, jeffxu@chromium.org wrote: > > > From: Jeff Xu > > > > > > Add sealing test to cover mmap for > > > Expand/shrink across sealed vmas (MAP_FIXED) > > > Reuse the same address in !MAP_FIXED case. > > > > This commit message is woefully small. I told you on v1 to improve the > > commit messages. Linus has told you to do this before. > > > > Please actually respond to feedback. Thanks. > > > > > > > > Signed-off-by: Jeff Xu > > > --- > > > tools/testing/selftests/mm/mseal_test.c | 126 ++++++++++++++++++++++= +- > > > 1 file changed, 125 insertions(+), 1 deletion(-) > > > > > > diff --git a/tools/testing/selftests/mm/mseal_test.c b/tools/testing/= selftests/mm/mseal_test.c > > > index e855c8ccefc3..3516389034a7 100644 > > > --- a/tools/testing/selftests/mm/mseal_test.c > > > +++ b/tools/testing/selftests/mm/mseal_test.c > > > @@ -2222,6 +2222,123 @@ static void test_munmap_free_multiple_ranges(= bool seal) > > > REPORT_TEST_PASS(); > > > } > > > > > > +static void test_seal_mmap_expand_seal_middle(bool seal) > > > > This test doesn't expand, doesn't do anything in the middle. It does mm= ap() > > though and relates to mseal, so that's something... this is compeltely > > misnamed and needs to be rethought. > > > > OK correction - it _seals_ in the middle. The remained of the criticism r= emains, > and this is rather confusing... and I continue to wonder what the purpose= of > this is? > It expands the size (start from ptr). > > > +{ > > > + void *ptr; > > > + unsigned long page_size =3D getpagesize(); > > > + unsigned long size =3D 12 * page_size; > > > + int ret; > > > + void *ret2; > > > + int prot; > > > + > > > + setup_single_address(size, &ptr); > > > > Please replace every single instance of this with an mmap(). There's > > literally no reason to abstract it. And munmap() what you map. > > No, we need to abstract it. In addition to the mmap, it also allocates an additional two blocks before and after the allocated memory, to avoid auto-merging, so we can use get_vma_size. > > > + FAIL_TEST_IF_FALSE(ptr !=3D (void *)-1); > > > > Pretty sure Pedro pointed out you should be checking against MAP_FAILED > > here. I really don't understand why the rest of your test is full of > > mmap()'s but for some reason you choose to abstract this one call? What= ? > > > > > + /* ummap last 4 pages. */ > > > + ret =3D sys_munmap(ptr + 8 * page_size, 4 * page_size); > > > > sys_munmap()? What's wrong with munmap()? > > > > > + FAIL_TEST_IF_FALSE(!ret); > > > > Why do we not have a FAIL_TEST_IF_TRUE()? This is crazy. > > > > Would be nice to have something human-readable like ASSERT_EQ() or > > ASSERT_TRUE() or ASSERT_FALSE(). > > ASSERT_EQ and ASSERT_TURE are not recommended by the self-test. The FAIL_TEST_IF_FAIL wrap will take care of some of the admin tasks related to self-test infra, such as count how many tests are failing. > > > + > > > + size =3D get_vma_size(ptr, &prot); > > > + FAIL_TEST_IF_FALSE(size =3D=3D 8 * page_size); > > > + FAIL_TEST_IF_FALSE(prot =3D=3D 0x4); > > > + > > > + if (seal) { > > > + ret =3D sys_mseal(ptr + 4 * page_size, 4 * page_size); > > > + FAIL_TEST_IF_FALSE(!ret); > > > + } > > > + > > > + /* use mmap to expand and overwrite (MAP_FIXED) */ > > > > You don't really need to say MAP_FIXED, it's below. > > Adding a comment here to help reviewers. > > > + ret2 =3D mmap(ptr, 12 * page_size, PROT_READ, > > > + MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0); > > > > Why read-only? > > > > You're not expanding you're overwriting. You're not doing anything in t= he > > middle. > > The MAP_FIXED is overwriting. It also expands the address range (start from ptr) from 8 to 12 pages. > > I'm again confused about what you think you're testing here. I don't th= ink > > we need an arbitrary MAP_FIXED mmap() at a size larger than the overwri= tten > > VMA? > > > > You just need a single instance of a MAP_FIXED mmap() over a sealed mma= p() > > if that's what you want. > > > > > + if (seal) { > > > + FAIL_TEST_IF_FALSE(ret2 =3D=3D MAP_FAILED); > > > + FAIL_TEST_IF_FALSE(errno =3D=3D EPERM); > > > + > > > + size =3D get_vma_size(ptr, &prot); > > > + FAIL_TEST_IF_FALSE(size =3D=3D 4 * page_size); > > > + FAIL_TEST_IF_FALSE(prot =3D=3D 0x4); > > > + > > > + size =3D get_vma_size(ptr + 4 * page_size, &prot); > > > + FAIL_TEST_IF_FALSE(size =3D=3D 4 * page_size); > > > + FAIL_TEST_IF_FALSE(prot =3D=3D 0x4); > > > + } else > > > + FAIL_TEST_IF_FALSE(ret2 =3D=3D ptr); > > > > Don't do dangling else's after a big block. > > patch passed the checkpatch.pl for style check. > > > + > > > + REPORT_TEST_PASS(); > > > +} > > > + > > > +static void test_seal_mmap_shrink_seal_middle(bool seal) > > > > What's going on in the 'middle'? This test doesn't shrink, it overwrite= s > > the beginning of a sealed VMA? > > Correction - the middle is sealed. Other points remain. > The mmap attempts to shrink the address range from 12 pages to 8 pages. > > > +{ > > > + void *ptr; > > > + unsigned long page_size =3D getpagesize(); > > > + unsigned long size =3D 12 * page_size; > > > + int ret; > > > + void *ret2; > > > + int prot; > > > + > > > + setup_single_address(size, &ptr); > > > + FAIL_TEST_IF_FALSE(ptr !=3D (void *)-1); > > > + > > > + if (seal) { > > > + ret =3D sys_mseal(ptr + 4 * page_size, 4 * page_size); > > > + FAIL_TEST_IF_FALSE(!ret); > > > + } > > > + > > > + /* use mmap to shrink and overwrite (MAP_FIXED) */ > > > > What exactly are you shrinking? You're overwriting the start of the vma= ? > > > > What is this testing that is different from the previous test? This see= ms > > useless honestly. > > Again, as above, one test is expanding, the other test is shrinking. Please take a look at mmap parameters and steps before mmap call. > > > + ret2 =3D mmap(ptr, 7 * page_size, PROT_READ, > > > + MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0); > > > + if (seal) { > > > + FAIL_TEST_IF_FALSE(ret2 =3D=3D MAP_FAILED); > > > + FAIL_TEST_IF_FALSE(errno =3D=3D EPERM); > > > + > > > + size =3D get_vma_size(ptr, &prot); > > > + FAIL_TEST_IF_FALSE(size =3D=3D 4 * page_size); > > > + FAIL_TEST_IF_FALSE(prot =3D=3D 0x4); > > > > What the hell is this comparison to magic numbers? This is > > ridiculous. What's wrong with PROT_xxx?? > > The PROT_xxx can't be used here. get_vma_size doesn't return PROT_ type, i.e. the bit sequence is different. > > > + > > > + size =3D get_vma_size(ptr + 4 * page_size, &prot); > > > + FAIL_TEST_IF_FALSE(size =3D=3D 4 * page_size); > > > + FAIL_TEST_IF_FALSE(prot =3D=3D 0x4); > > > + > > > + size =3D get_vma_size(ptr + 4 * page_size, &prot); > > > + FAIL_TEST_IF_FALSE(size =3D=3D 4 * page_size); > > > + FAIL_TEST_IF_FALSE(prot =3D=3D 0x4); > > > > Err dude, you're doing this twice? > > The second get_vma_size should be (ptr + 8 * page_size) I will update that. > > So what are we testing here exactly? That we got a VMA split? This is > > err... why are we asserting this? > > I guess, that we can't overwrite a sealed bit of a VMA at the end. But ag= ain > this feels entirely redundant. For this kind of thing to fail would mean = the > whole VMA machinery is broken. > The test is testing mmap(MAP_FIXED), since it can be used to overwrite the sealed memory range (without sealing), then there is a variant of expand/shrink. > > > > > + } else > > > + FAIL_TEST_IF_FALSE(ret2 =3D=3D ptr); > > > + > > > + REPORT_TEST_PASS(); > > > +} > > > + > > > +static void test_seal_mmap_reuse_addr(bool seal) > > > > This is wrong, you're not reusing anything. This test is useless. > > The ptr is reused as a hint. > > > +{ > > > + void *ptr; > > > + unsigned long page_size =3D getpagesize(); > > > + unsigned long size =3D page_size; > > > + int ret; > > > + void *ret2; > > > + int prot; > > > + > > > + setup_single_address(size, &ptr); > > > + FAIL_TEST_IF_FALSE(ptr !=3D (void *)-1); > > > + > > > + if (seal) { > > > + ret =3D sys_mseal(ptr, size); > > > + FAIL_TEST_IF_FALSE(!ret); > > > > We could avoid this horrid ret, ret2 naming if you just did: > > > > FAIL_TEST_IF_FALSE(sys_mseal(ptr, size)); > > > > > + } > > > + > > > + /* use mmap to change protection. */ > > > + ret2 =3D mmap(ptr, size, PROT_NONE, > > > + MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); > > > > How are you using mmap to change the protection when you're providing a > > hint to the address to use? You're not changing any protection at all! > > It is necessary to add the this tests to make sure mseal is behave as it should be, which is !MAP_FIXED case, new address will be allocated, instead of fail of mmap() > > You're allocating an entirely new VMA hinting that you want it near > > ptr. Please read the man page for mmap(): > > > > If addr is NULL, then the kernel chooses the (page-aligned) addr= ess > > at which to create the mapping; this is the most portable method= of > > creating a new mapping. If addr is not NULL, then the kernel ta= kes > > it as a hint about where to place the mapping; on Linux, the ker= nel > > will pick a nearby page boundary (but always above or equal to t= he > > value specified by /proc/sys/vm/mmap_min_addr) and attempt to cr= eate > > the mapping there. If another mapping already exists there, the > > kernel picks a new address that may or may not depend on the hin= t. > > The address of the new mapping is returned as the result of the > > call. > > > > > + > > > + /* MAP_FIXED is not used, expect new addr */ > > > + FAIL_TEST_IF_FALSE(!(ret2 =3D=3D MAP_FAILED)); > > > > This is beyond horrible. You really have to add more asserts. > > Again assert is not recommended by self_test > > Also you're expecting a new address here, so again, what on earth are y= ou > > asserting? That we can mmap()? > > > > > + FAIL_TEST_IF_FALSE(ret2 !=3D ptr); > > > + > > > + size =3D get_vma_size(ptr, &prot); > > > + FAIL_TEST_IF_FALSE(size =3D=3D page_size); > > > + FAIL_TEST_IF_FALSE(prot =3D=3D 0x4); > > > + > > > + REPORT_TEST_PASS(); > > > +} > > > + > > > int main(int argc, char **argv) > > > { > > > bool test_seal =3D seal_support(); > > > @@ -2243,7 +2360,7 @@ int main(int argc, char **argv) > > > if (!get_vma_size_supported()) > > > ksft_exit_skip("get_vma_size not supported\n"); > > > > > > - ksft_set_plan(91); > > > + ksft_set_plan(97); > > > > I'm guessing this is the number of tests, but I mean this is horrible. = Is > > there not a better way of doing this? > > Again, this is recommended by self-test. > > > > > > test_seal_addseal(); > > > test_seal_unmapped_start(); > > > @@ -2357,5 +2474,12 @@ int main(int argc, char **argv) > > > test_munmap_free_multiple_ranges(false); > > > test_munmap_free_multiple_ranges(true); > > > > > > + test_seal_mmap_expand_seal_middle(false); > > > + test_seal_mmap_expand_seal_middle(true); > > > + test_seal_mmap_shrink_seal_middle(false); > > > + test_seal_mmap_shrink_seal_middle(true); > > > + test_seal_mmap_reuse_addr(false); > > > + test_seal_mmap_reuse_addr(true); > > > + > > > ksft_finished(); > > > } > > > -- > > > 2.46.0.469.g59c65b2a67-goog > > >