From patchwork Mon Aug 27 18:56:26 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jann Horn X-Patchwork-Id: 10577587 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 D3CE95A4 for ; Mon, 27 Aug 2018 20:35:22 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C514E2A04C for ; Mon, 27 Aug 2018 20:35:22 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B70992A096; Mon, 27 Aug 2018 20:35:22 +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 CDABF2A04C for ; Mon, 27 Aug 2018 20:35:21 +0000 (UTC) Received: (qmail 23905 invoked by uid 550); 27 Aug 2018 20:35:20 -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 26142 invoked from network); 27 Aug 2018 18:58:08 -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=P251Yg4XTOGN9zPdxhNMgYM/EY0/UfzuP6Y77+vHpwGP/4ACr6sepDbjZrRXOio60G 7wpuql49VaYM0tJPqYeSiBYq5GeynF83vXviLqmdy9hNxYGGiSQTS94rXZvJ/XpgL2F9 RxwtGQuP37JVgQ1heB/5/cFE83tYYbR14GrSAFO6trSmAsY5CoWSJqGR1GklUSdceR8t 58GNr6vj+/OEUAHuLPp3FfZafThnevrtJavIBOsbqR8+DfMN7G5EjFupooDFlS/oIC/U 6EpJ3RH7tKZCaDtZP3ZlRjB1VUJJjkPGs5S4ClEynQsJ84UxoXPDpXz8oWNtKIqWOXfi 5iCQ== 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=RCzz9YQTUXKWljNKkHOMdh+WZaPMsV9FdJe3nRW8twCGkBelSyFTqsXldXat1U6kxe xk82aMUWErwTCYeab8Ru6+Qb2owFGjlDswD1NdKiT2H4F2ccvmD7FYlESJYa+ni6Snvj gccmFVwpCm2dVn7bCVWi4M5+c6mwPXu7SZOydSc7GWoDYS7es5D9eV3B2MXh7fyzyjbF Z97JohQDDLnOHSlzNDMSBiAnVjU1yooXcIUCEhawVPmGHQF3e2YP3FwwayH9EkHVzZU5 LvOjNS11Vpmtch1U+GL4PKpgFOz0GBO+co0MjA7i3GQhQNiF0HjMh+D7Hfk0TFdpiDSh ENdQ== X-Gm-Message-State: APzg51C4jpxiiibTpUOJQIWNDSUCppUrpX+tW86E0+kmosBUlKHAlFEK Ndhx3tnJn6iF8Cf5+qyD3YKRSPJUmQ== X-Google-Smtp-Source: ANB0VdaUfyo3zrWPEn2HbXdjdwG/E5fPLdmcTAdii0N1YRweY5xFts+AtOUalUPZ1IZQmYtZpTf8JHM4sg== X-Received: by 2002:a0c:d2da:: with SMTP id x26-v6mr19428qvh.36.1535396276214; Mon, 27 Aug 2018 11:57:56 -0700 (PDT) Date: Mon, 27 Aug 2018 20:56:26 +0200 In-Reply-To: <20180827185631.163506-1-jannh@google.com> Message-Id: <20180827185631.163506-3-jannh@google.com> Mime-Version: 1.0 References: <20180827185631.163506-1-jannh@google.com> X-Mailer: git-send-email 2.19.0.rc0.228.g281dcd1b4d0-goog Subject: [PATCH v2 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, Tony Luck , Borislav Petkov , jannh@google.com Cc: linux-kernel@vger.kernel.org, dvyukov@google.com, linux-edac@vger.kernel.org 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 --- 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);