From patchwork Fri Sep 21 15:13:39 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrey Konovalov X-Patchwork-Id: 10610391 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 75F0C15E8 for ; Fri, 21 Sep 2018 15:14:50 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6650828960 for ; Fri, 21 Sep 2018 15:14:50 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 587D62E46D; Fri, 21 Sep 2018 15:14:50 +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 D06152E49D for ; Fri, 21 Sep 2018 15:14:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391087AbeIUVDi (ORCPT ); Fri, 21 Sep 2018 17:03:38 -0400 Received: from mail-wr1-f65.google.com ([209.85.221.65]:42646 "EHLO mail-wr1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390685AbeIUVDh (ORCPT ); Fri, 21 Sep 2018 17:03:37 -0400 Received: by mail-wr1-f65.google.com with SMTP id v17-v6so13208760wrr.9 for ; Fri, 21 Sep 2018 08:14:16 -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=1q0PO0hPRCnT+r/aJv+LRNQrmrY8qkJccEfwzSBWRP0=; b=YwSnoOyog07VSpvYFTeD1mI6b54q8Bkeg21BNiVV2K/md4YJKQ6qvjUryTBGMm4m9W 5KR3cNZ96si6OUh73UDKlp0uy2hUTKrABBOxa/xA0KxwT69gGrgEcjDRvG9ezBGHBGyo IVen8IDdy9HOr0ySN8nbeduGeiZhYJZI0USM6UIgTufHwdsEthgpnrwHn+Aw/N71j5XL WN+Bo+sqAV7kdy9l/s2hiq61BWddzpiG21WLhApxn3yJU3xAYrhR6Eo/g56OAxwDWM+M sxRDjUw7CwEp60WuD5OQaZma2jDOzf09AB5Qnv+KJUYRkIVbzVJbsg2qSGToGcBOOnn4 vc+A== 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=1q0PO0hPRCnT+r/aJv+LRNQrmrY8qkJccEfwzSBWRP0=; b=J+AzNV/DnfGqASd6LWhfObte4uMLagU81ggtgJUGoFZpLDLlU4tzh4736UkGgwL7ja JAY721VJdueC5c6tlA+ZPuPLmvqamWDm96CDfcN7wYTj9h8Ekt+z2ac1fe7yyNomYj9b sev/zGiLPab5jIE6tOJqnkvhc/B7SUNONygCVwwOG4ACu+jJyjqZLUtPwtL0LNLqRYY7 lbqCqk7eFrKmreOK7UGHvEJD0jgXqaIlg2Ixz8Uybo4YRJQvBb5aoWC5dkZQlgVhC/1h yyLpVZkJQok3tAnG7MTLSpJPUUMdavoTofsv8PSBee3JRlEw90xv9oji+4Tb+3u/gbmg +ylQ== X-Gm-Message-State: APzg51DH0Qg/U9BAV2cWbbZBLd4FFCJVCOMCEsEpZ+QqmccZaByU9tEX 9+krEMpkpkLFBkw9oMvzSQYVPA== X-Google-Smtp-Source: ANB0VdanMcLHfejk+EKxl7zFxXgTqrKg3rgjDlJi+bWk6BvixIrRPPs/aq4791b9NbxiNbQQ0s7PwQ== X-Received: by 2002:a05:6000:108:: with SMTP id o8mr36832311wrx.196.1537542855833; Fri, 21 Sep 2018 08:14:15 -0700 (PDT) Received: from andreyknvl0.muc.corp.google.com ([2a00:79e0:15:10:84be:a42a:826d:c530]) by smtp.gmail.com with ESMTPSA id e7-v6sm27990271wru.46.2018.09.21.08.14.14 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 21 Sep 2018 08:14:15 -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 v9 17/20] kasan, arm64: add brk handler for inline instrumentation Date: Fri, 21 Sep 2018 17:13:39 +0200 Message-Id: <31b54fe2d9b950e9e8c9cd303808db35c730548c.1537542735.git.andreyknvl@google.com> X-Mailer: git-send-email 2.19.0.444.g18242da7ef-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 4c9d6f9029f2..d5a2a7f1f72c 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) { }