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=-18.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 EB95FC48BE8 for ; Mon, 14 Jun 2021 10:47:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CFE586194E for ; Mon, 14 Jun 2021 10:47:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232875AbhFNKt6 (ORCPT ); Mon, 14 Jun 2021 06:49:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:51420 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234034AbhFNKrv (ORCPT ); Mon, 14 Jun 2021 06:47:51 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 4BD7961411; Mon, 14 Jun 2021 10:37:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1623667048; bh=Vf0WjYnw4gbt73WQD6i2qUuSCrlySRycgEiqTg5lM/M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Xgpxj69LdYapeTc73K91iKX+kiUE5JswHewn54xkfpwWRuH2xMIfbDg7itVbV0SNG 71GG44VFmh2NaBhmFGF9Y3fJxnPFC1OOrJJh4c8yZpKt/71SPXh5fhw93Ue76ouz07 baFvAcUyJqKzfkNbtZafc/3sg8j0cWLfbXckZGbw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Christian Brauner , Andrea Righi , Kees Cook , Linus Torvalds Subject: [PATCH 5.4 01/84] proc: Track /proc/$pid/attr/ opener mm_struct Date: Mon, 14 Jun 2021 12:26:39 +0200 Message-Id: <20210614102646.389672488@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210614102646.341387537@linuxfoundation.org> References: <20210614102646.341387537@linuxfoundation.org> User-Agent: quilt/0.66 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Kees Cook commit 591a22c14d3f45cc38bd1931c593c221df2f1881 upstream. Commit bfb819ea20ce ("proc: Check /proc/$pid/attr/ writes against file opener") tried to make sure that there could not be a confusion between the opener of a /proc/$pid/attr/ file and the writer. It used struct cred to make sure the privileges didn't change. However, there were existing cases where a more privileged thread was passing the opened fd to a differently privileged thread (during container setup). Instead, use mm_struct to track whether the opener and writer are still the same process. (This is what several other proc files already do, though for different reasons.) Reported-by: Christian Brauner Reported-by: Andrea Righi Tested-by: Andrea Righi Fixes: bfb819ea20ce ("proc: Check /proc/$pid/attr/ writes against file opener") Cc: stable@vger.kernel.org Signed-off-by: Kees Cook Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- fs/proc/base.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -2527,6 +2527,11 @@ out: } #ifdef CONFIG_SECURITY +static int proc_pid_attr_open(struct inode *inode, struct file *file) +{ + return __mem_open(inode, file, PTRACE_MODE_READ_FSCREDS); +} + static ssize_t proc_pid_attr_read(struct file * file, char __user * buf, size_t count, loff_t *ppos) { @@ -2557,7 +2562,7 @@ static ssize_t proc_pid_attr_write(struc int rv; /* A task may only write when it was the opener. */ - if (file->f_cred != current_real_cred()) + if (file->private_data != current->mm) return -EPERM; rcu_read_lock(); @@ -2607,9 +2612,11 @@ out: } static const struct file_operations proc_pid_attr_operations = { + .open = proc_pid_attr_open, .read = proc_pid_attr_read, .write = proc_pid_attr_write, .llseek = generic_file_llseek, + .release = mem_release, }; #define LSM_DIR_OPS(LSM) \