From patchwork Mon Dec 13 21:55:40 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: andrey.konovalov@linux.dev X-Patchwork-Id: 12695999 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id DCEDCC433EF for ; Mon, 13 Dec 2021 22:28:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=s6dKq/dR+cSOnxPe4nSl1H+01QOd72E0JfMmtTc42/4=; b=HlOjldJxiL0zT7 aZ+hFXfToQXU0y1Jq5rNQOoir8GQXbxeT+LkSCIrLLdnA5R8qmFqydJ+v34Ay4NejiRZDZCGkOpIN uS+euT+EOAYPZbyaUpJeN00m5HMHk/hcZDGFSGLfHbbIqCcR4yaLJATkyckYdnSHHOt+S0znqWIu5 tAMuzoCnh3rJv4KIkCGaJeQZUffwebIdTVDJ9g5tcZPUl5C7vCmBvsT5Px/EJZ418Drzh4xoXkhNt Q1K43UQAMp92wxoVl72QG8Ekgo7zh+1I35a5ivDmN5mIPEMHCYZJVITwWPQkUs+Y4Caf02Slh/lR1 8kELC4JQcklzUvaQvK1A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mwtmj-00BjKW-6w; Mon, 13 Dec 2021 22:27:05 +0000 Received: from out0.migadu.com ([2001:41d0:2:267::]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mwtIa-00BX1P-T5 for linux-arm-kernel@lists.infradead.org; Mon, 13 Dec 2021 21:55:59 +0000 X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1639432555; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=atsw/HgrrU9UEfCA9neCOdaHXk4j162F8pSBON7qM7s=; b=bihdkVfTLCsUKtTc5+RCKvRuDP20xKGBlrbZuyVewg7+ajLcOxrFy03xEQQJI5qHNmPyq+ jZZo4YkNKe4odT4j0JWaXpC0NZx+bJZeG1iWpAPHU7qFh4sNOwufby6W42pOuC38c208cR TqPoSCwT7x12lAUAvLDuzDnvfRKh6G8= From: andrey.konovalov@linux.dev To: Marco Elver , Alexander Potapenko , Andrew Morton Cc: Andrey Konovalov , Dmitry Vyukov , Andrey Ryabinin , kasan-dev@googlegroups.com, linux-mm@kvack.org, Vincenzo Frascino , Catalin Marinas , Will Deacon , Mark Rutland , linux-arm-kernel@lists.infradead.org, Peter Collingbourne , Evgenii Stepanov , linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH mm v3 38/38] kasan: improve vmalloc tests Date: Mon, 13 Dec 2021 22:55:40 +0100 Message-Id: <3da23b9b90a4092dfc0e8355a974702985f6d426.1639432170.git.andreyknvl@google.com> In-Reply-To: References: MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Migadu-Auth-User: andrey.konovalov@linux.dev X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211213_135557_315102_A95F26B1 X-CRM114-Status: GOOD ( 18.57 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Andrey Konovalov Update the existing vmalloc_oob() test to account for the specifics of the tag-based modes. Also add a few new checks and comments. Add new vmalloc-related tests: - vmalloc_helpers_tags() to check that exported vmalloc helpers can handle tagged pointers. - vmap_tags() to check that SW_TAGS mode properly tags vmap() mappings. - vm_map_ram_tags() to check that SW_TAGS mode properly tags vm_map_ram() mappings. - vmalloc_percpu() to check that SW_TAGS mode tags regions allocated for __alloc_percpu(). The tagging of per-cpu mappings is best-effort; proper tagging is tracked in [1]. [1] https://bugzilla.kernel.org/show_bug.cgi?id=215019 Signed-off-by: Andrey Konovalov --- lib/test_kasan.c | 181 +++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 175 insertions(+), 6 deletions(-) diff --git a/lib/test_kasan.c b/lib/test_kasan.c index 847cdbefab46..a554aaec45cc 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -1049,21 +1049,174 @@ static void kmalloc_double_kzfree(struct kunit *test) KUNIT_EXPECT_KASAN_FAIL(test, kfree_sensitive(ptr)); } +static void vmalloc_helpers_tags(struct kunit *test) +{ + void *ptr; + + /* This test is intended for tag-based modes. */ + KASAN_TEST_NEEDS_CONFIG_OFF(test, CONFIG_KASAN_GENERIC); + + KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_VMALLOC); + + ptr = vmalloc(PAGE_SIZE); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); + + /* Check that the returned pointer is tagged. */ + KUNIT_EXPECT_GE(test, (u8)get_tag(ptr), (u8)KASAN_TAG_MIN); + KUNIT_EXPECT_LT(test, (u8)get_tag(ptr), (u8)KASAN_TAG_KERNEL); + + /* Make sure exported vmalloc helpers handle tagged pointers. */ + KUNIT_ASSERT_TRUE(test, is_vmalloc_addr(ptr)); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, vmalloc_to_page(ptr)); + + vfree(ptr); +} + static void vmalloc_oob(struct kunit *test) { - void *area; + char *v_ptr, *p_ptr; + struct page *page; + size_t size = PAGE_SIZE / 2 - KASAN_GRANULE_SIZE - 5; KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_VMALLOC); + v_ptr = vmalloc(size); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, v_ptr); + /* - * We have to be careful not to hit the guard page. + * We have to be careful not to hit the guard page in vmalloc tests. * The MMU will catch that and crash us. */ - area = vmalloc(3000); - KUNIT_ASSERT_NOT_ERR_OR_NULL(test, area); - KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)area)[3100]); - vfree(area); + /* Make sure in-bounds accesses are valid. */ + v_ptr[0] = 0; + v_ptr[size - 1] = 0; + + /* + * An unaligned access past the requested vmalloc size. + * Only generic KASAN can precisely detect these. + */ + if (IS_ENABLED(CONFIG_KASAN_GENERIC)) + KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)v_ptr)[size]); + + /* An aligned access into the first out-of-bounds granule. */ + KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)v_ptr)[size + 5]); + + /* Check that in-bounds accesses to the physical page are valid. */ + page = vmalloc_to_page(v_ptr); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, page); + p_ptr = page_address(page); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, p_ptr); + p_ptr[0] = 0; + + vfree(v_ptr); + + /* + * We can't check for use-after-unmap bugs in this nor in the following + * vmalloc tests, as the page might be fully unmapped and accessing it + * will crash the kernel. + */ +} + +static void vmap_tags(struct kunit *test) +{ + char *p_ptr, *v_ptr; + struct page *p_page, *v_page; + size_t order = 1; + + /* + * This test is specifically crafted for the software tag-based mode, + * the only tag-based mode that poisons vmap mappings. + */ + KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_SW_TAGS); + + KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_VMALLOC); + + p_page = alloc_pages(GFP_KERNEL, order); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, p_page); + p_ptr = page_address(p_page); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, p_ptr); + + v_ptr = vmap(&p_page, 1 << order, VM_MAP, PAGE_KERNEL); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, v_ptr); + + /* + * We can't check for out-of-bounds bugs in this nor in the following + * vmalloc tests, as allocations have page granularity and accessing + * the guard page will crash the kernel. + */ + + KUNIT_EXPECT_GE(test, (u8)get_tag(v_ptr), (u8)KASAN_TAG_MIN); + KUNIT_EXPECT_LT(test, (u8)get_tag(v_ptr), (u8)KASAN_TAG_KERNEL); + + /* Make sure that in-bounds accesses through both pointers work. */ + *p_ptr = 0; + *v_ptr = 0; + + /* Make sure vmalloc_to_page() correctly recovers the page pointer. */ + v_page = vmalloc_to_page(v_ptr); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, v_page); + KUNIT_EXPECT_PTR_EQ(test, p_page, v_page); + + vunmap(v_ptr); + free_pages((unsigned long)p_ptr, order); +} + +static void vm_map_ram_tags(struct kunit *test) +{ + char *p_ptr, *v_ptr; + struct page *page; + size_t order = 1; + + /* + * This test is specifically crafted for the software tag-based mode, + * the only tag-based mode that poisons vm_map_ram mappings. + */ + KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_SW_TAGS); + + page = alloc_pages(GFP_KERNEL, order); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, page); + p_ptr = page_address(page); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, p_ptr); + + v_ptr = vm_map_ram(&page, 1 << order, -1); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, v_ptr); + + KUNIT_EXPECT_GE(test, (u8)get_tag(v_ptr), (u8)KASAN_TAG_MIN); + KUNIT_EXPECT_LT(test, (u8)get_tag(v_ptr), (u8)KASAN_TAG_KERNEL); + + /* Make sure that in-bounds accesses through both pointers work. */ + *p_ptr = 0; + *v_ptr = 0; + + vm_unmap_ram(v_ptr, 1 << order); + free_pages((unsigned long)p_ptr, order); +} + +static void vmalloc_percpu(struct kunit *test) +{ + char __percpu *ptr; + int cpu; + + /* + * This test is specifically crafted for the software tag-based mode, + * the only tag-based mode that poisons percpu mappings. + */ + KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_SW_TAGS); + + ptr = __alloc_percpu(PAGE_SIZE, PAGE_SIZE); + + for_each_possible_cpu(cpu) { + char *c_ptr = per_cpu_ptr(ptr, cpu); + + KUNIT_EXPECT_GE(test, (u8)get_tag(c_ptr), (u8)KASAN_TAG_MIN); + KUNIT_EXPECT_LT(test, (u8)get_tag(c_ptr), (u8)KASAN_TAG_KERNEL); + + /* Make sure that in-bounds accesses don't crash the kernel. */ + *c_ptr = 0; + } + + free_percpu(ptr); } /* @@ -1097,6 +1250,18 @@ static void match_all_not_assigned(struct kunit *test) KUNIT_EXPECT_LT(test, (u8)get_tag(ptr), (u8)KASAN_TAG_KERNEL); free_pages((unsigned long)ptr, order); } + + if (!IS_ENABLED(CONFIG_KASAN_VMALLOC)) + return; + + for (i = 0; i < 256; i++) { + size = (get_random_int() % 1024) + 1; + ptr = vmalloc(size); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); + KUNIT_EXPECT_GE(test, (u8)get_tag(ptr), (u8)KASAN_TAG_MIN); + KUNIT_EXPECT_LT(test, (u8)get_tag(ptr), (u8)KASAN_TAG_KERNEL); + vfree(ptr); + } } /* Check that 0xff works as a match-all pointer tag for tag-based modes. */ @@ -1202,7 +1367,11 @@ static struct kunit_case kasan_kunit_test_cases[] = { KUNIT_CASE(kasan_bitops_generic), KUNIT_CASE(kasan_bitops_tags), KUNIT_CASE(kmalloc_double_kzfree), + KUNIT_CASE(vmalloc_helpers_tags), KUNIT_CASE(vmalloc_oob), + KUNIT_CASE(vmap_tags), + KUNIT_CASE(vm_map_ram_tags), + KUNIT_CASE(vmalloc_percpu), KUNIT_CASE(match_all_not_assigned), KUNIT_CASE(match_all_ptr_tag), KUNIT_CASE(match_all_mem_tag),