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=-9.5 required=3.0 tests=DKIM_ADSP_CUSTOM_MED, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 45CD5C2BB55 for ; Thu, 9 Apr 2020 12:39:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 280802078E for ; Thu, 9 Apr 2020 12:39:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726816AbgDIMjM (ORCPT ); Thu, 9 Apr 2020 08:39:12 -0400 Received: from raptor.unsafe.ru ([5.9.43.93]:58572 "EHLO raptor.unsafe.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726579AbgDIMiq (ORCPT ); Thu, 9 Apr 2020 08:38:46 -0400 Received: from comp-core-i7-2640m-0182e6.redhat.com (ip-89-102-33-211.net.upcbroadband.cz [89.102.33.211]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by raptor.unsafe.ru (Postfix) with ESMTPSA id 840AE209D8; Thu, 9 Apr 2020 12:38:43 +0000 (UTC) From: Alexey Gladkov To: LKML Cc: Kernel Hardening , Linux API , Linux FS Devel , Linux Security Module , Akinobu Mita , Alexander Viro , Alexey Dobriyan , Alexey Gladkov , Andrew Morton , Andy Lutomirski , Daniel Micay , Djalal Harouni , "Dmitry V . Levin" , "Eric W . Biederman" , Greg Kroah-Hartman , Ingo Molnar , "J . Bruce Fields" , Jeff Layton , Jonathan Corbet , Kees Cook , Linus Torvalds , Oleg Nesterov , David Howells Subject: [PATCH RESEND v11 4/8] proc: instantiate only pids that we can ptrace on 'hidepid=4' mount option Date: Thu, 9 Apr 2020 14:37:48 +0200 Message-Id: <20200409123752.1070597-5-gladkov.alexey@gmail.com> X-Mailer: git-send-email 2.25.2 In-Reply-To: <20200409123752.1070597-1-gladkov.alexey@gmail.com> References: <20200409123752.1070597-1-gladkov.alexey@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.6.1 (raptor.unsafe.ru [5.9.43.93]); Thu, 09 Apr 2020 12:38:44 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If "hidepid=4" mount option is set then do not instantiate pids that we can not ptrace. "hidepid=4" means that procfs should only contain pids that the caller can ptrace. Signed-off-by: Djalal Harouni Signed-off-by: Alexey Gladkov Reviewed-by: Alexey Dobriyan Reviewed-by: Kees Cook --- fs/proc/base.c | 15 +++++++++++++++ fs/proc/root.c | 13 ++++++++++--- include/linux/proc_fs.h | 1 + 3 files changed, 26 insertions(+), 3 deletions(-) diff --git a/fs/proc/base.c b/fs/proc/base.c index 43a28907baf9..1ebe9eba48ea 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -701,6 +701,14 @@ static bool has_pid_permissions(struct proc_fs_info *fs_info, struct task_struct *task, int hide_pid_min) { + /* + * If 'hidpid' mount option is set force a ptrace check, + * we indicate that we are using a filesystem syscall + * by passing PTRACE_MODE_READ_FSCREDS + */ + if (fs_info->hide_pid == HIDEPID_NOT_PTRACEABLE) + return ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS); + if (fs_info->hide_pid < hide_pid_min) return true; if (in_group_p(fs_info->pid_gid)) @@ -3319,7 +3327,14 @@ struct dentry *proc_pid_lookup(struct dentry *dentry, unsigned int flags) if (!task) goto out; + /* Limit procfs to only ptraceable tasks */ + if (fs_info->hide_pid == HIDEPID_NOT_PTRACEABLE) { + if (!has_pid_permissions(fs_info, task, HIDEPID_NO_ACCESS)) + goto out_put_task; + } + result = proc_pid_instantiate(dentry, task, NULL); +out_put_task: put_task_struct(task); out: return result; diff --git a/fs/proc/root.c b/fs/proc/root.c index 616e8976185c..62eae22403d2 100644 --- a/fs/proc/root.c +++ b/fs/proc/root.c @@ -47,6 +47,14 @@ static const struct fs_parameter_spec proc_fs_parameters[] = { {} }; +static inline int valid_hidepid(unsigned int value) +{ + return (value == HIDEPID_OFF || + value == HIDEPID_NO_ACCESS || + value == HIDEPID_INVISIBLE || + value == HIDEPID_NOT_PTRACEABLE); +} + static int proc_parse_param(struct fs_context *fc, struct fs_parameter *param) { struct proc_fs_context *ctx = fc->fs_private; @@ -63,10 +71,9 @@ static int proc_parse_param(struct fs_context *fc, struct fs_parameter *param) break; case Opt_hidepid: + if (!valid_hidepid(result.uint_32)) + return invalf(fc, "proc: unknown value of hidepid.\n"); ctx->hidepid = result.uint_32; - if (ctx->hidepid < HIDEPID_OFF || - ctx->hidepid > HIDEPID_INVISIBLE) - return invalfc(fc, "hidepid value must be between 0 and 2.\n"); break; default: diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h index 7d852dbca253..21d19353fdc7 100644 --- a/include/linux/proc_fs.h +++ b/include/linux/proc_fs.h @@ -32,6 +32,7 @@ enum { HIDEPID_OFF = 0, HIDEPID_NO_ACCESS = 1, HIDEPID_INVISIBLE = 2, + HIDEPID_NOT_PTRACEABLE = 4, /* Limit pids to only ptraceable pids */ }; struct proc_fs_info { -- 2.25.2