From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ua1-f74.google.com ([209.85.222.74]:32892 "EHLO mail-ua1-f74.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727328AbeH2AIB (ORCPT ); Tue, 28 Aug 2018 20:08:01 -0400 Received: by mail-ua1-f74.google.com with SMTP id z12-v6so1117804uao.0 for ; Tue, 28 Aug 2018 13:14:46 -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> 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 Content-Type: text/plain; charset="UTF-8" Sender: linux-fsdevel-owner@vger.kernel.org List-ID: 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); -- 2.19.0.rc0.228.g281dcd1b4d0-goog