From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753648AbbFOCYu (ORCPT ); Sun, 14 Jun 2015 22:24:50 -0400 Received: from e28smtp01.in.ibm.com ([122.248.162.1]:37353 "EHLO e28smtp01.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752093AbbFOCYl (ORCPT ); Sun, 14 Jun 2015 22:24:41 -0400 Message-ID: <557E375F.2000104@linux.vnet.ibm.com> Date: Mon, 15 Jun 2015 10:24:31 +0800 From: Li Zhang User-Agent: Mozilla/5.0 (X11; Linux i686; rv:17.0) Gecko/20130329 Thunderbird/17.0.5 MIME-Version: 1.0 To: Arnaldo Carvalho de Melo CC: mingo@redhat.com, sukadev@linux.vnet.ibm.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] perf tools: Check access permission when reading /proc/kcore file. References: <1433905293-16176-1-git-send-email-zhlcindy@linux.vnet.ibm.com> <20150610144452.GM3136@kernel.org> In-Reply-To: <20150610144452.GM3136@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15061502-4790-0000-0000-000008B315C8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2015年06月10日 22:44, Arnaldo Carvalho de Melo wrote: > Em Wed, Jun 10, 2015 at 11:01:33AM +0800, Li Zhang escreveu: >> When using command perf report --kallsyms=/proc/kallsyms with a non-root >> user, symbols are resolved. Then select one symbol and annotate it, it >> reports the error as the following: >> Can't annotate __clear_user: No vmlinux file with build id xxx was found. >> >> The problem is caused by reading /proc/kcore without access permission. >> It needs to change access permission to allow a specific user to read >> /proc/kcore or use root to execute the perf command. > But then only if the user tries it again, using -v to enable verbose > mode is that the message will be presented, how about instead return > -EPERM, or -errno, so that this error is propagated back and we > eventually emit a more meaningful message to the user, such as: > > "Insufficient permission to access %s.", kcore_filename > > Trying to check if that is possible by going to the dso__load_kcore() > callers and on back to the tools. This sounds much better. I will check whether it can deliver this message to user. Thanks Li > > - Arnaldo > >> This patch is to check access permission when reading kcore file. >> >> Signed-off-by: Li Zhang >> --- >> tools/perf/util/symbol.c | 5 +++++ >> 1 file changed, 5 insertions(+) >> >> diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c >> index 201f6c4c..8255556 100644 >> --- a/tools/perf/util/symbol.c >> +++ b/tools/perf/util/symbol.c >> @@ -1125,6 +1125,11 @@ static int dso__load_kcore(struct dso *dso, struct map *map, >> md.type = map->type; >> INIT_LIST_HEAD(&md.maps); >> >> + if (access(kcore_filename, R_OK)) { >> + pr_debug("Can't access file %s.\n", kcore_filename); >> + return -EINVAL; >> + } >> + >> fd = open(kcore_filename, O_RDONLY); >> if (fd < 0) >> return -EINVAL; >> -- >> 2.1.0 > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- Li Zhang IBM China Linux Technology Centre