From patchwork Wed Jun 20 17:40:00 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrey Konovalov X-Patchwork-Id: 10478357 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 0AF6E601D7 for ; Wed, 20 Jun 2018 17:45:40 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id EABE228DFB for ; Wed, 20 Jun 2018 17:45:39 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id DF43928E15; Wed, 20 Jun 2018 17:45:39 +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=-7.8 required=2.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI,T_DKIM_INVALID 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 6D0C028DFB for ; Wed, 20 Jun 2018 17:45:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754675AbeFTRoz (ORCPT ); Wed, 20 Jun 2018 13:44:55 -0400 Received: from mail-wm0-f68.google.com ([74.125.82.68]:37061 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754446AbeFTRkb (ORCPT ); Wed, 20 Jun 2018 13:40:31 -0400 Received: by mail-wm0-f68.google.com with SMTP id r125-v6so997989wmg.2 for ; Wed, 20 Jun 2018 10:40:31 -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; bh=d2bTqC19vsa63XvPHoNQzGVPuuGO11zOf+oXYC8d6zA=; b=J8GSmHG2otXy9GR1YQdnRkC73dWps4/X6XZJHUYtHxGdwrf0RP+nrwBpWWVoYkD/Ym psgAXSLW1JpjTg9CE7hfKtZ9z1SNUAVBvZnVDOm6LT9oCHibrrBJ7Y/WWvYhTQVgfpS9 n5uQ//s6KuyeML3iWRvEHRNd+YhdKJwLeFrRjhwjjM0Dp1+jo/a1+4T/wINZ+7+mfBmL qBEIaYWy58TTZ5WgV1yh4MJuvdsn1BqTu/wFwesEiIvb/wOOARDFv+wvbQ8/DKRD3Dj9 ZqZcVJ0/bu9w4BxpYaisxRm3Ap5gYHVP9bY1qtAEmMblo6HNKa7k7jobEwka4LZ8CtxE B5wg== 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; bh=d2bTqC19vsa63XvPHoNQzGVPuuGO11zOf+oXYC8d6zA=; b=jMbJ1pd8WSDn7hGY+YIBj55QfvPpkF7CHxBcWF4nlkD0jYkc3QajRN39TwC22RR5QR QH6dPloaHZ9H6UZNAnL+ZtiRiELdhtvI6Nev+5OSgTBZfKciUod9D3sn001aQEo3Dtws yQwV8jaye6LOK0XdcDU5gL6Tc4cJai5e0TQ4u2WLlTyZ/yo3/aBn4bp7/+DgTr/7a8+I 80gH1s9gGToCQAOXkBA9pfNyygX0j4BHp6d9zevdKiQ7dISdKkJmNQUd0lUL+Hgfgdd8 ++5j2icrpzkIGOCqOkvblEf99y1EE9iYjCx/98IxclWQ1Tjjma4wv9EbWRTZ4Ed2O9Qc GfoQ== X-Gm-Message-State: APt69E3BlNNMJB7RVTBoY6YKI076ims4QncR9lYOhB4g9MlkjOp434A8 C/rvrqNGhho5Wvv7kBBRqQlFyg== X-Google-Smtp-Source: ADUXVKJRB2kcQFAuw69CFMK4M7ftlSgIGxQ56RzmEZVOtDJeRSwnMsmdOXyz3MZ5NlLuthQj0awrIw== X-Received: by 2002:a1c:150d:: with SMTP id 13-v6mr2687933wmv.100.1529516429834; Wed, 20 Jun 2018 10:40:29 -0700 (PDT) Received: from andreyknvl0.muc.corp.google.com ([2a00:79e0:15:10:84be:a42a:826d:c530]) by smtp.gmail.com with ESMTPSA id f18-v6sm4388598wro.1.2018.06.20.10.40.28 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 20 Jun 2018 10:40:29 -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 , Andrey Konovalov Subject: [PATCH v3 14/17] khwasan, arm64: add brk handler for inline instrumentation Date: Wed, 20 Jun 2018 19:40:00 +0200 Message-Id: <6660ebcd8b5c7b70b91731cb62dff85be5a94684.1529515183.git.andreyknvl@google.com> X-Mailer: git-send-email 2.18.0.rc1.244.gcf134e6275-goog In-Reply-To: References: 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 KHWASAN 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 add a KHWASAN 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 | 69 +++++++++++++++++++++++++++++++- 2 files changed, 69 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/brk-imm.h b/arch/arm64/include/asm/brk-imm.h index ed693c5bcec0..e4a7013321dc 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: KHWASAN 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 KHWASAN_BRK_IMM 0x900 #endif diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index d399d459397b..95152a4fd202 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. @@ -791,7 +796,7 @@ 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; } @@ -801,6 +806,59 @@ static struct break_hook bug_break_hook = { .fn = bug_handler, }; +#ifdef CONFIG_KASAN_HW + +#define KHWASAN_ESR_RECOVER 0x20 +#define KHWASAN_ESR_WRITE 0x10 +#define KHWASAN_ESR_SIZE_MASK 0x0f +#define KHWASAN_ESR_SIZE(esr) (1 << ((esr) & KHWASAN_ESR_SIZE_MASK)) + +static int khwasan_handler(struct pt_regs *regs, unsigned int esr) +{ + bool recover = esr & KHWASAN_ESR_RECOVER; + bool write = esr & KHWASAN_ESR_WRITE; + size_t size = KHWASAN_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. KHWASAN reporting is disabled in some contexts (for example when + * the allocator accesses slab object metadata; same is true for KASAN; + * 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 - KHWASAN", 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 KHWASAN_ESR_VAL (0xf2000000 | KHWASAN_BRK_IMM) +#define KHWASAN_ESR_MASK 0xffffff00 + +static struct break_hook khwasan_break_hook = { + .esr_val = KHWASAN_ESR_VAL, + .esr_mask = KHWASAN_ESR_MASK, + .fn = khwasan_handler, +}; +#endif + /* * Initial handler for AArch64 BRK exceptions * This handler only used until debug_traps_init(). @@ -808,6 +866,10 @@ static struct break_hook bug_break_hook = { int __init early_brk64(unsigned long addr, unsigned int esr, struct pt_regs *regs) { +#ifdef CONFIG_KASAN_HW + if ((esr & KHWASAN_ESR_MASK) == KHWASAN_ESR_VAL) + return khwasan_handler(regs, esr) != DBG_HOOK_HANDLED; +#endif return bug_handler(regs, esr) != DBG_HOOK_HANDLED; } @@ -815,4 +877,7 @@ int __init early_brk64(unsigned long addr, unsigned int esr, void __init trap_init(void) { register_break_hook(&bug_break_hook); +#ifdef CONFIG_KASAN_HW + register_break_hook(&khwasan_break_hook); +#endif }