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=-12.5 required=3.0 tests=BAYES_00, 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,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 57AD2C5517A for ; Fri, 6 Nov 2020 15:17:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 106232222B for ; Fri, 6 Nov 2020 15:17:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727705AbgKFPP3 (ORCPT ); Fri, 6 Nov 2020 10:15:29 -0500 Received: from raptor.unsafe.ru ([5.9.43.93]:46034 "EHLO raptor.unsafe.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727346AbgKFPP0 (ORCPT ); Fri, 6 Nov 2020 10:15:26 -0500 Received: from comp-core-i7-2640m-0182e6.redhat.com (ip-89-103-122-167.net.upcbroadband.cz [89.103.122.167]) (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 8542620A0A; Fri, 6 Nov 2020 15:15:23 +0000 (UTC) From: Alexey Gladkov To: LKML , Linux FS Devel , "Eric W . Biederman" Cc: Alexey Gladkov , Alexander Viro , Kees Cook Subject: [PATCH v4 2/3] proc: Show /proc/self/net only for CAP_NET_ADMIN Date: Fri, 6 Nov 2020 16:15:11 +0100 Message-Id: <8b31b58cd5331f86e6f5a927168ce3b8e97ca760.1604675649.git.gladkov.alexey@gmail.com> X-Mailer: git-send-email 2.25.4 In-Reply-To: References: 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]); Fri, 06 Nov 2020 15:15:23 +0000 (UTC) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Cache the mounters credentials and make access to the net directories contingent of the permissions of the mounter of proc. Show /proc/self/net only if mounter has CAP_NET_ADMIN and if proc is mounted with subset=pid option. Signed-off-by: Alexey Gladkov --- fs/proc/proc_net.c | 8 ++++++++ fs/proc/root.c | 7 +++++++ include/linux/proc_fs.h | 1 + 3 files changed, 16 insertions(+) diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c index dba63b2429f0..c43fc5c907db 100644 --- a/fs/proc/proc_net.c +++ b/fs/proc/proc_net.c @@ -26,6 +26,7 @@ #include #include #include +#include #include "internal.h" @@ -275,6 +276,7 @@ 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); @@ -287,6 +289,12 @@ 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 051ffe5e67ce..0ab90e24d9ae 100644 --- a/fs/proc/root.c +++ b/fs/proc/root.c @@ -185,6 +185,8 @@ static int proc_fill_super(struct super_block *s, struct fs_context *fc) s->s_fs_info = fs_info; fs_info->pid_ns = get_pid_ns(ctx->pid_ns); + fs_info->mounter_cred = get_cred(fc->cred); + proc_apply_options(s, fc, current_user_ns()); /* @@ -220,9 +222,13 @@ static int proc_fill_super(struct super_block *s, struct fs_context *fc) static int proc_reconfigure(struct fs_context *fc) { struct super_block *sb = fc->root->d_sb; + struct proc_fs_info *fs_info = proc_sb_info(sb); sync_filesystem(sb); + put_cred(fs_info->mounter_cred); + fs_info->mounter_cred = get_cred(fc->cred); + proc_apply_options(sb, fc, current_user_ns()); return 0; } @@ -277,6 +283,7 @@ 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 d1eed1b43651..ce00560789f6 100644 --- a/include/linux/proc_fs.h +++ b/include/linux/proc_fs.h @@ -63,6 +63,7 @@ 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) -- 2.25.4