From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1746D3AF667; Mon, 13 Apr 2026 11:22:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776079353; cv=none; b=IVaSoVu403HObIDtz9g4ohgK39/GNSClVad5RPXCcPjXeIRCRua3I73Ss5xKOIK0qeOjLUuqFxSTptd57iWWrcAgx7QTUVqbeAGlQZKMGchk+DjWTQWvfXBKEdAreBgr2qATcvRxYQGaC3zUqEnFeCgxXBoCyY5d8UQi3yRlxtQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776079353; c=relaxed/simple; bh=FQCr7qSm4xiBoSTBWH1BWq5L0Ay30j0R812NdJ+wUOo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=s95zweFacok+PRi1tGRqcFL5QMqbkZjzeibq0NE0bU2bpTER5PjTScwtL9VZEAui+4jARAya6lqC8iGNdwLjkzCDKjslXrBoSzXaQgdjuaU1moyy3RcPitBr/9jG+dP3sSPSK7Lm65eMNAGZrxhBQNMVxx2SRT+7KF5Bxozs7LY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LUlf+U5a; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LUlf+U5a" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E68BFC19421; Mon, 13 Apr 2026 11:22:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776079352; bh=FQCr7qSm4xiBoSTBWH1BWq5L0Ay30j0R812NdJ+wUOo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LUlf+U5aaLSmGeHO6JW2lnpMimJXxFosndPsDyVSddbVMfaEMCtX5PmW2NwFmveiM EOKLr72aSD30kD99QMxV2JT9bMZ2uW6ppBOlXPuSJWJCSO1FmX5ScbhMhHSbolaEM9 rOVmuMTKWGaLjUkFhN+hPlIk9745WDu2RTPoItxxj7ySY7DJWHMRQfsf6bcPtZ9Q7d KaCwP9sE3fkWOPq4pfJtbfBBPWJnkVvw3xQDjUObK6BpQnG3bmdOOmM9+dKOL8zQo5 oWeBbCTIsf7YAghYOhuVVigN7VSs0ruAfJyNQSeTJn5KdAFkNYcCgBiGYqwTsYJRoP p9a/32MzcsndQ== From: Alexey Gladkov To: Christian Brauner , Dan Klishch Cc: Al Viro , "Eric W . Biederman" , Kees Cook , containers@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v9 2/5] proc: subset=pid: Show /proc/self/net only for CAP_NET_ADMIN Date: Mon, 13 Apr 2026 13:19:41 +0200 Message-ID: X-Mailer: git-send-email 2.53.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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. To avoid inadvertently allowing access to /proc//net, updating mounter credentials is not supported. Signed-off-by: Alexey Gladkov --- fs/proc/proc_net.c | 8 ++++++++ fs/proc/root.c | 2 ++ include/linux/proc_fs.h | 1 + 3 files changed, 11 insertions(+) diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c index 52f0b75cbce2..6e0ccef0169f 100644 --- a/fs/proc/proc_net.c +++ b/fs/proc/proc_net.c @@ -23,6 +23,7 @@ #include #include #include +#include #include "internal.h" @@ -270,6 +271,7 @@ 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); @@ -282,6 +284,12 @@ 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 0f9100559471..6d18f9ee0375 100644 --- a/fs/proc/root.c +++ b/fs/proc/root.c @@ -254,6 +254,7 @@ 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 */ @@ -350,6 +351,7 @@ static void proc_kill_sb(struct super_block *sb) kill_anon_super(sb); if (fs_info) { put_pid_ns(fs_info->pid_ns); + put_cred(fs_info->mounter_cred); kfree_rcu(fs_info, rcu); } } diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h index 19d1c5e5f335..ec123c277d49 100644 --- a/include/linux/proc_fs.h +++ b/include/linux/proc_fs.h @@ -67,6 +67,7 @@ enum proc_pidonly { struct proc_fs_info { struct pid_namespace *pid_ns; kgid_t pid_gid; + const struct cred *mounter_cred; enum proc_hidepid hide_pid; enum proc_pidonly pidonly; struct rcu_head rcu; -- 2.53.0