From patchwork Wed Sep 19 18:54:56 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrey Konovalov X-Patchwork-Id: 10606269 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 2E45C6CB for ; Wed, 19 Sep 2018 18:56:17 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1F84929178 for ; Wed, 19 Sep 2018 18:56:17 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 114482AF40; Wed, 19 Sep 2018 18:56:17 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.5 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, USER_IN_DEF_DKIM_WL autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8762029178 for ; Wed, 19 Sep 2018 18:56:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387622AbeITAfY (ORCPT ); Wed, 19 Sep 2018 20:35:24 -0400 Received: from mail-wm1-f65.google.com ([209.85.128.65]:40743 "EHLO mail-wm1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387621AbeITAer (ORCPT ); Wed, 19 Sep 2018 20:34:47 -0400 Received: by mail-wm1-f65.google.com with SMTP id 207-v6so8119138wme.5 for ; Wed, 19 Sep 2018 11:55:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=64LRcqLvQSyCxvtv4IJ7rTIUII9l3vNlb4g5rc8vkL0=; b=hG9jAuyfvJ6nmCLNRdOdKKDU/2noEnfGgoX0leHX6iQZldPCbscRBlWSJE3B2Wzi/O ZaUfp8B2+Qadav3L2H4Up8N03Nw8tAJvYLlfKkEGF4skQXLzxEDrkUT532pP54vzG8qr 7bPUEbYZ0YEL6Tfu2toFS7lfFjhECtPiVupq6PPpWzbVLRvM/K3WwxZf9T3qWMlDBkqI H5NHnPTs/+zAqNY1gbfZw1oPqXfqv43KjJv4HXNZkzPfg1Hubqs6Fx9fHnpb83bxh0jb OhWoUoVm1uiSP67dp6nhom0qRHgvZVJUljvE3sVKrultK0LfGxBxm9t2lV7yJ/4Lgkf3 A90w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=64LRcqLvQSyCxvtv4IJ7rTIUII9l3vNlb4g5rc8vkL0=; b=Whaqz1vzSIkK6tx3Fh+b6bVcj+Z5vfk49WFSdzUda+o2pTxjn/PZ08VeqS6uy+HvaD Gw6vf0aqRAZmrkiY2UVdWvJp/DiS+diseBLD2gjeI5kcZpMke/ORMsRgkn6a6KMnaJWi 9Btu7PseVJ9p8SxC4ddPqNM0iesb73OVbzUGOD+caGgGHAAzTG4VDmIwJ+pQ09zvN2qz ViN3f+kPsJfhNWebkGlDY9iCcmgOtDhCeiS95H0JBLr/K6WSqq3QQEU5TUJnKIkwUrHi ObTLt66s6cm2XZNCK7gh/xbrEPs6MMAcAUByr1YXXy3UttcssQ8+AkKYgN5YbjLKCL2N jlZw== X-Gm-Message-State: APzg51BSK7TM5NEyHN3xw01CPR6P3L7bfImw3pngEbJaNoRDr7txOcDN irkN2Ae/FnO8WqAJTIakHfq6pg== X-Google-Smtp-Source: ANB0VdYGftNhd7nwokX4PuREsLaMzahfl8OPDSKHDJ8LczN3UlzH89oiQnT+xB4L6rm0/DrVRyz9yw== X-Received: by 2002:a1c:208c:: with SMTP id g134-v6mr7666265wmg.144.1537383330821; Wed, 19 Sep 2018 11:55:30 -0700 (PDT) Received: from andreyknvl0.muc.corp.google.com ([2a00:79e0:15:10:84be:a42a:826d:c530]) by smtp.gmail.com with ESMTPSA id b10-v6sm8510065wmc.28.2018.09.19.11.55.29 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 19 Sep 2018 11:55:30 -0700 (PDT) From: Andrey Konovalov To: Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , Catalin Marinas , Will Deacon , Christoph Lameter , Andrew Morton , Mark Rutland , Nick Desaulniers , Marc Zyngier , Dave Martin , Ard Biesheuvel , "Eric W . Biederman" , Ingo Molnar , Paul Lawrence , Geert Uytterhoeven , Arnd Bergmann , "Kirill A . Shutemov" , Greg Kroah-Hartman , Kate Stewart , Mike Rapoport , kasan-dev@googlegroups.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-sparse@vger.kernel.org, linux-mm@kvack.org, linux-kbuild@vger.kernel.org Cc: Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Jann Horn , Mark Brand , Chintan Pandya , Vishwath Mohan , Andrey Konovalov Subject: [PATCH v8 17/20] kasan, arm64: add brk handler for inline instrumentation Date: Wed, 19 Sep 2018 20:54:56 +0200 Message-Id: X-Mailer: git-send-email 2.19.0.397.gdd90340f6a-goog In-Reply-To: References: MIME-Version: 1.0 Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Tag-based KASAN inline instrumentation mode (which embeds checks of shadow memory into the generated code, instead of inserting a callback) generates a brk instruction when a tag mismatch is detected. This commit adds a tag-based KASAN specific brk handler, that decodes the immediate value passed to the brk instructions (to extract information about the memory access that triggered the mismatch), reads the register values (x0 contains the guilty address) and reports the bug. Signed-off-by: Andrey Konovalov --- arch/arm64/include/asm/brk-imm.h | 2 + arch/arm64/kernel/traps.c | 68 +++++++++++++++++++++++++++++++- include/linux/kasan.h | 3 ++ 3 files changed, 71 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/brk-imm.h b/arch/arm64/include/asm/brk-imm.h index ed693c5bcec0..2945fe6cd863 100644 --- a/arch/arm64/include/asm/brk-imm.h +++ b/arch/arm64/include/asm/brk-imm.h @@ -16,10 +16,12 @@ * 0x400: for dynamic BRK instruction * 0x401: for compile time BRK instruction * 0x800: kernel-mode BUG() and WARN() traps + * 0x9xx: tag-based KASAN trap (allowed values 0x900 - 0x9ff) */ #define FAULT_BRK_IMM 0x100 #define KGDB_DYN_DBG_BRK_IMM 0x400 #define KGDB_COMPILED_DBG_BRK_IMM 0x401 #define BUG_BRK_IMM 0x800 +#define KASAN_BRK_IMM 0x900 #endif diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index 039e9ff379cc..ca0c00f5b6dd 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -35,6 +35,7 @@ #include #include #include +#include #include #include @@ -269,10 +270,14 @@ void arm64_notify_die(const char *str, struct pt_regs *regs, } } -void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size) +void __arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size) { regs->pc += size; +} +void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size) +{ + __arm64_skip_faulting_instruction(regs, size); /* * If we were single stepping, we want to get the step exception after * we return from the trap. @@ -775,7 +780,7 @@ static int bug_handler(struct pt_regs *regs, unsigned int esr) } /* If thread survives, skip over the BUG instruction and continue: */ - arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); + __arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); return DBG_HOOK_HANDLED; } @@ -785,6 +790,58 @@ static struct break_hook bug_break_hook = { .fn = bug_handler, }; +#ifdef CONFIG_KASAN_SW_TAGS + +#define KASAN_ESR_RECOVER 0x20 +#define KASAN_ESR_WRITE 0x10 +#define KASAN_ESR_SIZE_MASK 0x0f +#define KASAN_ESR_SIZE(esr) (1 << ((esr) & KASAN_ESR_SIZE_MASK)) + +static int kasan_handler(struct pt_regs *regs, unsigned int esr) +{ + bool recover = esr & KASAN_ESR_RECOVER; + bool write = esr & KASAN_ESR_WRITE; + size_t size = KASAN_ESR_SIZE(esr); + u64 addr = regs->regs[0]; + u64 pc = regs->pc; + + if (user_mode(regs)) + return DBG_HOOK_ERROR; + + kasan_report(addr, size, write, pc); + + /* + * The instrumentation allows to control whether we can proceed after + * a crash was detected. This is done by passing the -recover flag to + * the compiler. Disabling recovery allows to generate more compact + * code. + * + * Unfortunately disabling recovery doesn't work for the kernel right + * now. KASAN reporting is disabled in some contexts (for example when + * the allocator accesses slab object metadata; this is controlled by + * current->kasan_depth). All these accesses are detected by the tool, + * even though the reports for them are not printed. + * + * This is something that might be fixed at some point in the future. + */ + if (!recover) + die("Oops - KASAN", regs, 0); + + /* If thread survives, skip over the brk instruction and continue: */ + __arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); + return DBG_HOOK_HANDLED; +} + +#define KASAN_ESR_VAL (0xf2000000 | KASAN_BRK_IMM) +#define KASAN_ESR_MASK 0xffffff00 + +static struct break_hook kasan_break_hook = { + .esr_val = KASAN_ESR_VAL, + .esr_mask = KASAN_ESR_MASK, + .fn = kasan_handler, +}; +#endif + /* * Initial handler for AArch64 BRK exceptions * This handler only used until debug_traps_init(). @@ -792,6 +849,10 @@ static struct break_hook bug_break_hook = { int __init early_brk64(unsigned long addr, unsigned int esr, struct pt_regs *regs) { +#ifdef CONFIG_KASAN_SW_TAGS + if ((esr & KASAN_ESR_MASK) == KASAN_ESR_VAL) + return kasan_handler(regs, esr) != DBG_HOOK_HANDLED; +#endif return bug_handler(regs, esr) != DBG_HOOK_HANDLED; } @@ -799,4 +860,7 @@ int __init early_brk64(unsigned long addr, unsigned int esr, void __init trap_init(void) { register_break_hook(&bug_break_hook); +#ifdef CONFIG_KASAN_SW_TAGS + register_break_hook(&kasan_break_hook); +#endif } diff --git a/include/linux/kasan.h b/include/linux/kasan.h index 7e5be87a05b3..59bd67de63d9 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -173,6 +173,9 @@ void kasan_init_tags(void); void *kasan_reset_tag(const void *addr); +void kasan_report(unsigned long addr, size_t size, + bool is_write, unsigned long ip); + #else /* CONFIG_KASAN_SW_TAGS */ static inline void kasan_init_tags(void) { }