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[2620:137:e000::1:20]) by mx.google.com with ESMTP id j191-20020a638bc8000000b004fb49e919f7si8393782pge.550.2023.03.07.06.28.41; Tue, 07 Mar 2023 06:28:54 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=TRNBdv0N; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231504AbjCGONd (ORCPT + 99 others); Tue, 7 Mar 2023 09:13:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59594 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230191AbjCGOMj (ORCPT ); Tue, 7 Mar 2023 09:12:39 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 534498315C for ; Tue, 7 Mar 2023 06:09:28 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 5F8C4B818FE for ; Tue, 7 Mar 2023 14:08:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 29C8BC433A0; Tue, 7 Mar 2023 14:08:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1678198121; bh=gZ6gT92QoewG67ylJsd53DevrQCpgBq5112YtMXuQRo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TRNBdv0NFEKBnS2lFqek4SATtENdEPGBRch+JF41rd9uNvJhbI17ES1Td3abUFDER Ke6ptVpzc28DJ1gF0r+NHw1mFqi2YHyp7EDnh6fOpae2aHwCBDKhUWx4vYGX32vHgA 9ObQl4V/08s/85qs1tljGmIOYbsd99LB4S3a6A8DNFcuLnXl3Z/jPimstby0RP1CGl eE5ZSVjT1mweedTOg7ca8Ig3cdZ7h/f+hU6o1NVlBnK/JCSb1NjlMrerDZuMvgw93K Bj0yluZ6KFNOUtnqGvTaIMcYp9gT/WedJDVZe7Wrca4HkHdsEbJ7E5DyhfIEit5Nfr CWRK8+qbRq5Ng== From: Ard Biesheuvel To: linux-kernel@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org, Ard Biesheuvel , Catalin Marinas , Will Deacon , Marc Zyngier , Mark Rutland , Ryan Roberts , Anshuman Khandual , Kees Cook Subject: [PATCH v3 51/60] arm64: kasan: Reduce minimum shadow alignment and enable 5 level paging Date: Tue, 7 Mar 2023 15:05:13 +0100 Message-Id: <20230307140522.2311461-52-ardb@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230307140522.2311461-1-ardb@kernel.org> References: <20230307140522.2311461-1-ardb@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=9265; i=ardb@kernel.org; h=from:subject; bh=gZ6gT92QoewG67ylJsd53DevrQCpgBq5112YtMXuQRo=; b=owGbwMvMwCFmkMcZplerG8N4Wi2JIYXdpS2Xof1souYOwccVnnP/nZX7HPXzp8WNVaXc3Y1ru pkreQo6SlkYxDgYZMUUWQRm/3238/REqVrnWbIwc1iZQIYwcHEKwEQSEhgZOvK/PnTfUsn9ItrP vE9HPLs8NSbG5P2Oo1V6Fs3bQrS3MTIcFXq0xyzk0wO3XSemrC/hsX9QkbFLTiX2y6yHb2XCFFz 5AA== X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1759719544827127224?= X-GMAIL-MSGID: =?utf-8?q?1759719544827127224?= Allow the KASAN init code to deal with 5 levels of paging, and relax the requirement that the shadow region is aligned to the top level pgd_t size. This is necessary for LPA2 based 52-bit virtual addressing, where the KASAN shadow will never be aligned to the pgd_t size. Allowing this also enables the 16k/48-bit case for KASAN, which is a nice bonus. This involves some hackery to manipulate the root and next level page tables without having to distinguish all the various configurations, including 16k/48-bits (which has a two entry pgd_t level), and LPA2 configurations running with one translation level less on non-LPA2 hardware. Signed-off-by: Ard Biesheuvel --- arch/arm64/Kconfig | 2 +- arch/arm64/mm/kasan_init.c | 143 ++++++++++++++++++-- 2 files changed, 130 insertions(+), 15 deletions(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index d287dad29198c843..52aac583823863e4 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -157,7 +157,7 @@ config ARM64 select HAVE_ARCH_HUGE_VMAP select HAVE_ARCH_JUMP_LABEL select HAVE_ARCH_JUMP_LABEL_RELATIVE - select HAVE_ARCH_KASAN if !(ARM64_16K_PAGES && ARM64_VA_BITS_48) + select HAVE_ARCH_KASAN select HAVE_ARCH_KASAN_VMALLOC if HAVE_ARCH_KASAN select HAVE_ARCH_KASAN_SW_TAGS if HAVE_ARCH_KASAN select HAVE_ARCH_KASAN_HW_TAGS if (HAVE_ARCH_KASAN && ARM64_MTE) diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c index 7e32f21fb8e1e227..7ab7520133946e91 100644 --- a/arch/arm64/mm/kasan_init.c +++ b/arch/arm64/mm/kasan_init.c @@ -23,7 +23,7 @@ #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) -static pgd_t tmp_pg_dir[PTRS_PER_PGD] __initdata __aligned(PGD_SIZE); +static pgd_t tmp_pg_dir[PTRS_PER_PTE] __initdata __aligned(PAGE_SIZE); /* * The p*d_populate functions call virt_to_phys implicitly so they can't be used @@ -99,6 +99,19 @@ static pud_t *__init kasan_pud_offset(p4d_t *p4dp, unsigned long addr, int node, return early ? pud_offset_kimg(p4dp, addr) : pud_offset(p4dp, addr); } +static p4d_t *__init kasan_p4d_offset(pgd_t *pgdp, unsigned long addr, int node, + bool early) +{ + if (pgd_none(READ_ONCE(*pgdp))) { + phys_addr_t p4d_phys = early ? + __pa_symbol(kasan_early_shadow_p4d) + : kasan_alloc_zeroed_page(node); + __pgd_populate(pgdp, p4d_phys, PGD_TYPE_TABLE); + } + + return early ? p4d_offset_kimg(pgdp, addr) : p4d_offset(pgdp, addr); +} + static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr, unsigned long end, int node, bool early) { @@ -144,12 +157,12 @@ static void __init kasan_p4d_populate(pgd_t *pgdp, unsigned long addr, unsigned long end, int node, bool early) { unsigned long next; - p4d_t *p4dp = p4d_offset(pgdp, addr); + p4d_t *p4dp = kasan_p4d_offset(pgdp, addr, node, early); do { next = p4d_addr_end(addr, end); kasan_pud_populate(p4dp, addr, next, node, early); - } while (p4dp++, addr = next, addr != end); + } while (p4dp++, addr = next, addr != end && p4d_none(READ_ONCE(*p4dp))); } static void __init kasan_pgd_populate(unsigned long addr, unsigned long end, @@ -165,14 +178,48 @@ static void __init kasan_pgd_populate(unsigned long addr, unsigned long end, } while (pgdp++, addr = next, addr != end); } +#if defined(CONFIG_ARM64_64K_PAGES) || CONFIG_PGTABLE_LEVELS > 4 +#define SHADOW_ALIGN P4D_SIZE +#else +#define SHADOW_ALIGN PUD_SIZE +#endif + +/* + * Return whether 'addr' is aligned to the size covered by a root level + * descriptor. + */ +static bool __init root_level_aligned(u64 addr) +{ + int shift = (ARM64_HW_PGTABLE_LEVELS(vabits_actual) - 1) * (PAGE_SHIFT - 3); + + return (addr % (PAGE_SIZE << shift)) == 0; +} + /* The early shadow maps everything to a single page of zeroes */ asmlinkage void __init kasan_early_init(void) { BUILD_BUG_ON(KASAN_SHADOW_OFFSET != KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT))); - BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS), PGDIR_SIZE)); - BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS_MIN), PGDIR_SIZE)); - BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE)); + BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS), SHADOW_ALIGN)); + BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS_MIN), SHADOW_ALIGN)); + BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, SHADOW_ALIGN)); + + if (!root_level_aligned(KASAN_SHADOW_START)) { + /* + * The start address is misaligned, and so the next level table + * will be shared with the linear region. This can happen with + * 4 or 5 level paging, so install a generic pte_t[] as the + * next level. This prevents the kasan_pgd_populate call below + * from inserting an entry that refers to the shared KASAN zero + * shadow pud_t[]/p4d_t[], which could end up getting corrupted + * when the linear region is mapped. + */ + static pte_t tbl[PTRS_PER_PTE] __page_aligned_bss; + pgd_t *pgdp = pgd_offset_k(KASAN_SHADOW_START); + + set_pgd(pgdp, __pgd(__pa_symbol(tbl) | PGD_TYPE_TABLE)); + } + kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE, true); } @@ -184,20 +231,75 @@ static void __init kasan_map_populate(unsigned long start, unsigned long end, kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false); } -static void __init clear_pgds(unsigned long start, - unsigned long end) +/* + * Return the descriptor index of 'addr' in the root level table + */ +static int __init root_level_idx(u64 addr) { /* - * Remove references to kasan page tables from - * swapper_pg_dir. pgd_clear() can't be used - * here because it's nop on 2,3-level pagetable setups + * On 64k pages, the TTBR1 range root tables are extended for 52-bit + * virtual addressing, and TTBR1 will simply point to the pgd_t entry + * that covers the start of the 48-bit addressable VA space if LVA is + * not implemented. This means we need to index the table as usual, + * instead of masking off bits based on vabits_actual. */ - for (; start < end; start += PGDIR_SIZE) - set_pgd(pgd_offset_k(start), __pgd(0)); + u64 vabits = IS_ENABLED(CONFIG_ARM64_64K_PAGES) ? VA_BITS + : vabits_actual; + int shift = (ARM64_HW_PGTABLE_LEVELS(vabits) - 1) * (PAGE_SHIFT - 3); + + return (addr & ~_PAGE_OFFSET(vabits)) >> (shift + PAGE_SHIFT); +} + +/* + * Clone a next level table from swapper_pg_dir into tmp_pg_dir + */ +static void __init clone_next_level(u64 addr, pgd_t *tmp_pg_dir, pud_t *pud) +{ + int idx = root_level_idx(addr); + pgd_t pgd = READ_ONCE(swapper_pg_dir[idx]); + pud_t *pudp = (pud_t *)__phys_to_kimg(__pgd_to_phys(pgd)); + + memcpy(pud, pudp, PAGE_SIZE); + tmp_pg_dir[idx] = __pgd(__phys_to_pgd_val(__pa_symbol(pud)) | + PUD_TYPE_TABLE); +} + +/* + * Return the descriptor index of 'addr' in the next level table + */ +static int __init next_level_idx(u64 addr) +{ + int shift = (ARM64_HW_PGTABLE_LEVELS(vabits_actual) - 2) * (PAGE_SHIFT - 3); + + return (addr >> (shift + PAGE_SHIFT)) % PTRS_PER_PTE; +} + +/* + * Dereference the table descriptor at 'pgd_idx' and clear the entries from + * 'start' to 'end' (exclusive) from the table. + */ +static void __init clear_next_level(int pgd_idx, int start, int end) +{ + pgd_t pgd = READ_ONCE(swapper_pg_dir[pgd_idx]); + pud_t *pudp = (pud_t *)__phys_to_kimg(__pgd_to_phys(pgd)); + + memset(&pudp[start], 0, (end - start) * sizeof(pud_t)); +} + +static void __init clear_shadow(u64 start, u64 end) +{ + int l = root_level_idx(start), m = root_level_idx(end); + + if (!root_level_aligned(start)) + clear_next_level(l++, next_level_idx(start), PTRS_PER_PTE); + if (!root_level_aligned(end)) + clear_next_level(m, 0, next_level_idx(end)); + memset(&swapper_pg_dir[l], 0, (m - l) * sizeof(pgd_t)); } static void __init kasan_init_shadow(void) { + static pud_t pud[2][PTRS_PER_PUD] __initdata __aligned(PAGE_SIZE); u64 kimg_shadow_start, kimg_shadow_end; u64 mod_shadow_start, mod_shadow_end; u64 vmalloc_shadow_end; @@ -220,10 +322,23 @@ static void __init kasan_init_shadow(void) * setup will be finished. */ memcpy(tmp_pg_dir, swapper_pg_dir, sizeof(tmp_pg_dir)); + + /* + * If the start or end address of the shadow region is not aligned to + * the root level size, we have to allocate a temporary next-level table + * in each case, clone the next level of descriptors, and install the + * table into tmp_pg_dir. Note that with 5 levels of paging, the next + * level will in fact be p4d_t, but that makes no difference in this + * case. + */ + if (!root_level_aligned(KASAN_SHADOW_START)) + clone_next_level(KASAN_SHADOW_START, tmp_pg_dir, pud[0]); + if (!root_level_aligned(KASAN_SHADOW_END)) + clone_next_level(KASAN_SHADOW_END, tmp_pg_dir, pud[1]); dsb(ishst); cpu_replace_ttbr1(lm_alias(tmp_pg_dir)); - clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END); + clear_shadow(KASAN_SHADOW_START, KASAN_SHADOW_END); kasan_map_populate(kimg_shadow_start, kimg_shadow_end, early_pfn_to_nid(virt_to_pfn(lm_alias(KERNEL_START))));