From patchwork Tue Aug 28 20:14:16 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jann Horn X-Patchwork-Id: 10579167 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 A70D514BD for ; Tue, 28 Aug 2018 21:08:06 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9E23D2A961 for ; Tue, 28 Aug 2018 21:08:06 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 91A692A964; Tue, 28 Aug 2018 21:08:06 +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=-12.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED, USER_IN_DEF_DKIM_WL autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id 32DAE2A961 for ; Tue, 28 Aug 2018 21:08:04 +0000 (UTC) Received: (qmail 22482 invoked by uid 550); 28 Aug 2018 21:08:03 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Delivered-To: moderator for kernel-hardening@lists.openwall.com Received: (qmail 1502 invoked from network); 28 Aug 2018 20:14:56 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=uJWoCGq+dC+kv6D5HnpJpcUVVj9VCc0+wlPJZZu58Ic=; b=MRO1epmGNwUCnHbU0i4f57VR08as3uyxoIBp5RmzwmlCtcWAZJpI/2we+TaZa0z2Ln 3CrQkFyomt9BxMQNrkOBsV/YeVZN7p0iSiAehzruglhiG7k0hmVwlAzkxmiXtor6HVR8 aT9r5T4hsK7PawtQzM7IesKSESdyb3FO4V3bFN+gYo6L0zwP7B6OWqaAqB3ZiYh7lXJb 7SPdAY3RQ/DIrZb/kkiP/6f/txQyJ+f2WxkbINoeft9TbTBfUC1EdzbX8XJhMSldC4iT WK0q9e7si8qmOK7RWk5k4lF0hwIfI9BwmmORBhUTIGJTbB9v7RMieIa30NrxStXHDa45 SubQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=uJWoCGq+dC+kv6D5HnpJpcUVVj9VCc0+wlPJZZu58Ic=; b=C8UMqjFVYotDHsx9ADvr+ENhns/whwTPIt3l7pLL39MeS467kiSD9T7H2DA01PFOiW 2CugB+Ifv6mqlqRfbtQivVoHeTSVKfG6dP40ISJAbuxxyaMAG8p+n0CSNZGULa31rZLD mapZmKqtFIlq8BvkaCIljTIjodEkoO4zjIKaCAZKA9wIqs5FSDfcKHBRJMPm7tc8DNUm tDs5tBv7p4/qHEXz/elEIVxMXBMXoeoa/ikzPXoctz/BYetp3tU3rLBFtg7ny2PqqKeD qtrDvQ96wFv9bfdQ4zCHxuMvvL70aYK5v6Qq1Cz64fYTSvQZq7ejtKw2lutFmDGJ7uGN ZVQg== X-Gm-Message-State: APzg51B+6D+CyQkQdHP9GXVoYw5WgHbFwTTOqEiZhOJyEa9kFNuFjLsI KGzFbkNggUGGwTffYkpTgRIGQBdMWQ== X-Google-Smtp-Source: ANB0VdbkegCsYkP9pgf34tu1wuFJg7i0BU53xS/AZqQ1qT0piv2l5bWT4weTcWV+ofjP9fz0MVA73wFxiQ== X-Received: by 2002:a67:341d:: with SMTP id b29-v6mr901vsa.53.1535487285116; Tue, 28 Aug 2018 13:14:45 -0700 (PDT) Date: Tue, 28 Aug 2018 22:14:16 +0200 In-Reply-To: <20180828201421.157735-1-jannh@google.com> Message-Id: <20180828201421.157735-3-jannh@google.com> Mime-Version: 1.0 References: <20180828201421.157735-1-jannh@google.com> X-Mailer: git-send-email 2.19.0.rc0.228.g281dcd1b4d0-goog Subject: [PATCH v3 2/7] x86: inline kprobe_exceptions_notify() into do_general_protection() From: Jann Horn To: Kees Cook , Thomas Gleixner , Ingo Molnar , x86@kernel.org, Andy Lutomirski , kernel-hardening@lists.openwall.com, jannh@google.com Cc: linux-kernel@vger.kernel.org, dvyukov@google.com, Masami Hiramatsu , "Naveen N. Rao" , Anil S Keshavamurthy , "David S. Miller" , Alexander Viro , linux-fsdevel@vger.kernel.org, Borislav Petkov X-Virus-Scanned: ClamAV using ClamSMTP The opaque plumbing of #GP from do_general_protection() through notify_die() into kprobe_exceptions_notify() makes it hard to understand what's going on. Suggested-by: Andy Lutomirski Signed-off-by: Jann Horn Acked-by: Masami Hiramatsu --- arch/x86/kernel/kprobes/core.c | 31 +------------------------------ arch/x86/kernel/traps.c | 10 ++++++++++ 2 files changed, 11 insertions(+), 30 deletions(-) diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index b0d1e81c96bb..467ac22691b0 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -1028,42 +1028,13 @@ int kprobe_fault_handler(struct pt_regs *regs, int trapnr) if (fixup_exception(regs, trapnr)) return 1; - /* - * fixup routine could not handle it, - * Let do_page_fault() fix it. - */ + /* fixup routine could not handle it. */ } return 0; } NOKPROBE_SYMBOL(kprobe_fault_handler); -/* - * Wrapper routine for handling exceptions. - */ -int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, - void *data) -{ - struct die_args *args = data; - int ret = NOTIFY_DONE; - - if (args->regs && user_mode(args->regs)) - return ret; - - if (val == DIE_GPF) { - /* - * To be potentially processing a kprobe fault and to - * trust the result from kprobe_running(), we have - * be non-preemptible. - */ - if (!preemptible() && kprobe_running() && - kprobe_fault_handler(args->regs, args->trapnr)) - ret = NOTIFY_STOP; - } - return ret; -} -NOKPROBE_SYMBOL(kprobe_exceptions_notify); - bool arch_within_kprobe_blacklist(unsigned long addr) { bool is_in_entry_trampoline_section = false; diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index e6db475164ed..bf9ab1aaa175 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -556,6 +556,16 @@ do_general_protection(struct pt_regs *regs, long error_code) tsk->thread.error_code = error_code; tsk->thread.trap_nr = X86_TRAP_GP; + + /* + * To be potentially processing a kprobe fault and to + * trust the result from kprobe_running(), we have to + * be non-preemptible. + */ + if (!preemptible() && kprobe_running() && + kprobe_fault_handler(regs, X86_TRAP_GP)) + return; + if (notify_die(DIE_GPF, "general protection fault", regs, error_code, X86_TRAP_GP, SIGSEGV) != NOTIFY_STOP) die("general protection fault", regs, error_code);