From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932601AbdBVNyS (ORCPT ); Wed, 22 Feb 2017 08:54:18 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:39986 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932497AbdBVNyF (ORCPT ); Wed, 22 Feb 2017 08:54:05 -0500 From: "Naveen N. Rao" To: Masami Hiramatsu , Ananth N Mavinakayanahalli , Ingo Molnar , Michael Ellerman , Arnaldo Carvalho de Melo , Steven Rostedt Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: [PATCH v2 1/5] kretprobes: ensure probe location is at function entry Date: Wed, 22 Feb 2017 19:23:37 +0530 X-Mailer: git-send-email 2.11.0 In-Reply-To: References: In-Reply-To: References: X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 17022213-0004-0000-0000-00000541B294 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17022213-0005-0000-0000-0000133BB50C Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-02-22_08:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1612050000 definitions=main-1702220132 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org kretprobes can be registered by specifying an absolute address or by specifying offset to a symbol. However, we need to ensure this falls at function entry so as to be able to determine the return address. Validate the same during kretprobe registration. By default, there should not be any offset from a function entry, as determined through a kallsyms_lookup(). Introduce arch_function_offset_within_entry() as a way for architectures to override this. Signed-off-by: Naveen N. Rao --- include/linux/kprobes.h | 1 + kernel/kprobes.c | 13 +++++++++++++ 2 files changed, 14 insertions(+) diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h index 16ddfb8b304a..862f87adcbb4 100644 --- a/include/linux/kprobes.h +++ b/include/linux/kprobes.h @@ -266,6 +266,7 @@ extern int arch_init_kprobes(void); extern void show_registers(struct pt_regs *regs); extern void kprobes_inc_nmissed_count(struct kprobe *p); extern bool arch_within_kprobe_blacklist(unsigned long addr); +extern bool arch_function_offset_within_entry(unsigned long offset); extern bool within_kprobe_blacklist(unsigned long addr); diff --git a/kernel/kprobes.c b/kernel/kprobes.c index ebb4dadca66b..524766563896 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1869,12 +1869,25 @@ static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs) } NOKPROBE_SYMBOL(pre_handler_kretprobe); +bool __weak arch_function_offset_within_entry(unsigned long offset) +{ + return !offset; +} + int register_kretprobe(struct kretprobe *rp) { int ret = 0; struct kretprobe_instance *inst; int i; void *addr; + unsigned long offset; + + addr = kprobe_addr(&rp->kp); + if (!kallsyms_lookup_size_offset((unsigned long)addr, NULL, &offset)) + return -EINVAL; + + if (!arch_function_offset_within_entry(offset)) + return -EINVAL; if (kretprobe_blacklist_size) { addr = kprobe_addr(&rp->kp); -- 2.11.0