From patchwork Thu Dec 6 12:24:38 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrey Konovalov X-Patchwork-Id: 10715815 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 90443417B for ; Thu, 6 Dec 2018 12:26:02 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7E76D2D393 for ; Thu, 6 Dec 2018 12:26:02 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 71F6E292C8; Thu, 6 Dec 2018 12:26:02 +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 ECE28292C8 for ; Thu, 6 Dec 2018 12:26:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729810AbeLFMZY (ORCPT ); Thu, 6 Dec 2018 07:25:24 -0500 Received: from mail-wr1-f68.google.com ([209.85.221.68]:34691 "EHLO mail-wr1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729788AbeLFMZX (ORCPT ); Thu, 6 Dec 2018 07:25:23 -0500 Received: by mail-wr1-f68.google.com with SMTP id j2so326990wrw.1 for ; Thu, 06 Dec 2018 04:25:22 -0800 (PST) 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=8QlaS0qsWG1yDbCjfy8LBUBTA+Rw+V2QPlm0PJyeSSg=; b=LsjRIxQ2Hg3H9BfqO/BSaILu2cdnc7qCbrmOzsOCUGyNFhUc8PnZkY4Egonci94tcT oGHXVZT1R9v4uuwxW3lbEzK0xJNmrXmA0CrGXKmwmvmQgvnJPA8oS6+Mh8Wr515huKnW B1p3JEa9Idn8rpYKkd1KbBxd/uE3XKajY4oEmghl0YtQaZOluoD1ESC50TmFIiB/e8k4 vn+OvVg8Rzgxq2WOQiiif+qeJsYAk+UGskBhy3Bgcq83aIgG5r+YMz+jCc/MQouKb5wU dVg662Xv02eMWz6ce2DWFZEM9V4x0pl3o++UNARFS4dLPxk5oJAsyBCqxWcOZnuTW9y4 xEUg== 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=8QlaS0qsWG1yDbCjfy8LBUBTA+Rw+V2QPlm0PJyeSSg=; b=IZMjlnvynsWn/JvpmqKc0NhdQNKnTDge0W9hG7UTVZtZQf38ObmzSAmsc/zKsn+Ak8 v+soII9YhFt/KYgjT4xgpQXXX2H+GrlAd/LubXCOZ/+POfjlwCWbSwXSDAwKcDWcE0sq 2q+26f2cr/kC9KGcwps1zuzlaCx0oRFMgkZKI3DSic6XB0JUaB1yr/p5xA+IM0r1dV5D SnYwy+yTfGREuXwKsbH4iT2TpP4R5azDkC8vcucvD4LmF9bqk+hTg1J95sXLufiYVxeT dW95kW0hM2n0C68lNYbfMHkxoWBhkgXYEpJRwyOSGftD6tJtZm8ipgwoZoR5DQXcBcxu ZcKg== X-Gm-Message-State: AA+aEWZS7Ey3pb+sly+jimwhunfqO6R2pTHwl4tJ+N2F314ONrmpbFNd JVEjKivh5/q4UpI+vbHx+2m/xQ== X-Google-Smtp-Source: AFSGD/VRP3hJMLZE9HUeyiuuoJtI6GiUO+gXdz3duhVebumhgQr+5FnxHw+wLbZ5iNZKH1EKg0nbSA== X-Received: by 2002:a5d:6187:: with SMTP id j7mr25422579wru.300.1544099121225; Thu, 06 Dec 2018 04:25:21 -0800 (PST) Received: from andreyknvl0.muc.corp.google.com ([2a00:79e0:15:10:3180:41f8:3010:ff61]) by smtp.gmail.com with ESMTPSA id j8sm339988wrt.40.2018.12.06.04.25.19 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 06 Dec 2018 04:25:20 -0800 (PST) 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 v13 20/25] kasan, arm64: add brk handler for inline instrumentation Date: Thu, 6 Dec 2018 13:24:38 +0100 Message-Id: X-Mailer: git-send-email 2.20.0.rc1.387.gf8505762e3-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. Reviewed-by: Andrey Ryabinin Reviewed-by: Dmitry Vyukov Signed-off-by: Andrey Konovalov --- arch/arm64/include/asm/brk-imm.h | 2 ++ arch/arm64/kernel/traps.c | 60 ++++++++++++++++++++++++++++++++ include/linux/kasan.h | 3 ++ 3 files changed, 65 insertions(+) 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 5f4d9acb32f5..cdc71cf70aad 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -35,6 +35,7 @@ #include #include #include +#include #include #include @@ -969,6 +970,58 @@ 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(). @@ -976,6 +1029,10 @@ 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; } @@ -983,4 +1040,7 @@ 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 a477ce2abdc9..8da7b7a4397a 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) { }