From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C8B4FC433E6 for ; Mon, 31 Aug 2020 08:37:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A73D52073A for ; Mon, 31 Aug 2020 08:37:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728043AbgHaIhP (ORCPT ); Mon, 31 Aug 2020 04:37:15 -0400 Received: from mx2.suse.de ([195.135.220.15]:40542 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726102AbgHaIhO (ORCPT ); Mon, 31 Aug 2020 04:37:14 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 470B8B5B1 for ; Mon, 31 Aug 2020 08:37:47 +0000 (UTC) From: Qu Wenruo To: linux-kernel@vger.kernel.org Cc: jeyu@suse.de Subject: [PATCH] module: Add more error message for failed kernel module loading Date: Mon, 31 Aug 2020 16:37:05 +0800 Message-Id: <20200831083705.20807-1-wqu@suse.com> X-Mailer: git-send-email 2.28.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When kernel module loading failed, user space only get one of the following error messages: - -ENOEXEC This is the most confusing one. From corrupted ELF header to bad WRITE|EXEC flags check introduced by in module_enforce_rwx_sections() all returns this error number. - -EPERM This is for blacklisted modules. But mod doesn't do extra explain on this error either. - -ENOMEM The only error which needs no explain. This means, if a user got "Exec format error" from modprobe, it provides no meaningful way for the user to debug, and will take extra time communicating to get extra info. So this patch will add extra error messages for -ENOEXEC and -EPERM errors, allowing user to do better debugging and reporting. Signed-off-by: Qu Wenruo --- kernel/module.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/kernel/module.c b/kernel/module.c index 8fa2600bde6a..204bf29437b8 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2068,8 +2068,12 @@ static int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, int i; for (i = 0; i < hdr->e_shnum; i++) { - if ((sechdrs[i].sh_flags & shf_wx) == shf_wx) + if ((sechdrs[i].sh_flags & shf_wx) == shf_wx) { + pr_err( + "Module %s section %d has invalid WRITE|EXEC flags\n", + mod->name, i); return -ENOEXEC; + } } return 0; @@ -3797,8 +3801,10 @@ static int load_module(struct load_info *info, const char __user *uargs, char *after_dashes; err = elf_header_check(info); - if (err) + if (err) { + pr_err("Module has invalid ELF header\n"); goto free_copy; + } err = setup_load_info(info, flags); if (err) @@ -3806,6 +3812,7 @@ static int load_module(struct load_info *info, const char __user *uargs, if (blacklisted(info->name)) { err = -EPERM; + pr_err("Module %s is blacklisted\n", info->name); goto free_copy; } -- 2.28.0