From patchwork Fri Jul 16 10:46:00 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexey Gladkov X-Patchwork-Id: 12381957 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=-19.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 6D428C07E95 for ; Fri, 16 Jul 2021 10:46:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5633C61402 for ; Fri, 16 Jul 2021 10:46:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239587AbhGPKtn (ORCPT ); Fri, 16 Jul 2021 06:49:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:52108 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239574AbhGPKtm (ORCPT ); Fri, 16 Jul 2021 06:49:42 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 0E419613FA; Fri, 16 Jul 2021 10:46:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1626432407; bh=k94Nu9x4NfJTP2j35vA7U1lCV+pD0uPq7Q7Q46LODhk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Y9TPjGZK1UCZwhURm34297lo4Z4vXjM8WQXFSsTvUHCkucMGSlLL87RiN9ivzav2p gt6EgzD1kMAvkyoOIHhEE0cf44jqPbc/yaLA9/IusaD1fwkJ7jeq7w73pWVTsQtWl8 VGTG2ik2x4N+4UnHjZchWM7v4zABcAV3ayETXMztdRRCNBg4U0rK4oqTLfHuF0chz1 PNiYGYS3FpFmPc4/X9ZQ5cpzO5l+L2hBbG1z5SIgT5GpQ1zcYwhkALDZe3MKOJ3ij+ MRv+xQhZwklfQvyDedo1dS/fV0rO3/69FXZQxVFQ0LBq93lJguOOjTS96hPgHQUfOZ ZgCtwZDrEzbug== From: Alexey Gladkov To: LKML , "Eric W . Biederman" Cc: Alexander Viro , Kees Cook , Linux Containers , Linux FS Devel Subject: [RESEND PATCH v6 2/5] proc: subset=pid: Show /proc/self/net only for CAP_NET_ADMIN Date: Fri, 16 Jul 2021 12:46:00 +0200 Message-Id: X-Mailer: git-send-email 2.29.3 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Cache the mounters credentials and allow access to the net directories contingent of the permissions of the mounter of proc. Do not show /proc/self/net when proc is mounted with subset=pid option and the mounter does not have CAP_NET_ADMIN. Signed-off-by: Alexey Gladkov --- fs/proc/proc_net.c | 8 ++++++++ fs/proc/root.c | 5 +++++ include/linux/proc_fs.h | 1 + 3 files changed, 14 insertions(+) diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c index 18601042af99..a198f74cdb3b 100644 --- a/fs/proc/proc_net.c +++ b/fs/proc/proc_net.c @@ -26,6 +26,7 @@ #include #include #include +#include #include "internal.h" @@ -259,6 +260,7 @@ static struct net *get_proc_task_net(struct inode *dir) struct task_struct *task; struct nsproxy *ns; struct net *net = NULL; + struct proc_fs_info *fs_info = proc_sb_info(dir->i_sb); rcu_read_lock(); task = pid_task(proc_pid(dir), PIDTYPE_PID); @@ -271,6 +273,12 @@ static struct net *get_proc_task_net(struct inode *dir) } rcu_read_unlock(); + if (net && (fs_info->pidonly == PROC_PIDONLY_ON) && + security_capable(fs_info->mounter_cred, net->user_ns, CAP_NET_ADMIN, CAP_OPT_NONE) < 0) { + put_net(net); + net = NULL; + } + return net; } diff --git a/fs/proc/root.c b/fs/proc/root.c index 5e444d4f9717..6a75ac717455 100644 --- a/fs/proc/root.c +++ b/fs/proc/root.c @@ -171,6 +171,7 @@ static int proc_fill_super(struct super_block *s, struct fs_context *fc) return -ENOMEM; fs_info->pid_ns = get_pid_ns(ctx->pid_ns); + fs_info->mounter_cred = get_cred(fc->cred); proc_apply_options(fs_info, fc, current_user_ns()); /* User space would break if executables or devices appear on proc */ @@ -220,6 +221,9 @@ static int proc_reconfigure(struct fs_context *fc) sync_filesystem(sb); + put_cred(fs_info->mounter_cred); + fs_info->mounter_cred = get_cred(fc->cred); + proc_apply_options(fs_info, fc, current_user_ns()); return 0; } @@ -274,6 +278,7 @@ static void proc_kill_sb(struct super_block *sb) kill_anon_super(sb); put_pid_ns(fs_info->pid_ns); + put_cred(fs_info->mounter_cred); kfree(fs_info); } diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h index 000cc0533c33..ffa871941bd0 100644 --- a/include/linux/proc_fs.h +++ b/include/linux/proc_fs.h @@ -64,6 +64,7 @@ struct proc_fs_info { kgid_t pid_gid; enum proc_hidepid hide_pid; enum proc_pidonly pidonly; + const struct cred *mounter_cred; }; static inline struct proc_fs_info *proc_sb_info(struct super_block *sb)