From nobody Thu Apr 2 22:05:40 2026 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 B70AF3542C3; Fri, 13 Feb 2026 10:44:50 +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=1770979490; cv=none; b=eS4hMiP6GNsz1afxGQI2jU2BPsrq6f8vRIitQFYO8FWYsWq2sSdu8gRw/X2odKSVJdnRLgaNvEGKpNAjj+IxSkUHFQpxqWtrAsp1W1OiFlgkLBC++FEMicpGgtmQZnH733FCrIZKkbeQLOABrKj0K/SArvLBOVR7x4n12LVaJ3c= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770979490; c=relaxed/simple; bh=kpXfv1aQjmRM7Lisa9SQR+o6ZN41NjPHRd8/uCOz0mA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=PbCvygkvp3Vy6G1Di9ylIRnd4ouUxihKEm0abkIL+VxBvq9L27F9fDmP+dwYJUeJD9bYYY71jnRNOT7ue8aOOShnREqoEjqgF/H/9BUd9Bpz9BY1AbnvGDlUgwY8eFETp5rDu8p4IXMsR4cMavGLec1YPcFQKpVhBIi0bRUtDx4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=CJnjD40A; 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="CJnjD40A" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BCD0AC16AAE; Fri, 13 Feb 2026 10:44:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770979490; bh=kpXfv1aQjmRM7Lisa9SQR+o6ZN41NjPHRd8/uCOz0mA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CJnjD40AgaXOaFd2bB3q+hhoLOS7vWRMoLrKTwdz6g7aDZe1E48kbxJQgtAlhsC1D KaZRQ1JaeyEaZAV3MV24Z2x4k2jHBI7MqMv9O0AOGiqxgAk8lAxRCHM2wVrKnX4hoE +H9m9Z6hZIP2J88prwda4mJ2TsrF+vX7kRsjqAeJEgPUMP73P7HP/IsLEiFSaehydr qfeF5ropfWFfOnT6B9JWg13kBmbaOmhtDvapThmWfiNKqnWlb/ucjjpzbZ42ZgR0CU 056TURduuQmvC9m4W6hY84cjeSZtRDva6ENfXUGMZsYV76Up7GiWN38/sjP9rMZVt/ P6DfLmco3Ttig== From: Alexey Gladkov To: Christian Brauner , Dan Klishch Cc: Al Viro , "Eric W . Biederman" , Kees Cook , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v8 2/5] proc: subset=pid: Show /proc/self/net only for CAP_NET_ADMIN Date: Fri, 13 Feb 2026 11:44:27 +0100 Message-ID: <624eb242fab38fd01589fb5cb51c65617620be89.1770979341.git.legion@kernel.org> 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: quoted-printable Content-Type: text/plain; charset="utf-8" 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=3Dpid 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 =20 #include "internal.h" =20 @@ -270,6 +271,7 @@ static struct net *get_proc_task_net(struct inode *dir) struct task_struct *task; struct nsproxy *ns; struct net *net =3D NULL; + struct proc_fs_info *fs_info =3D proc_sb_info(dir->i_sb); =20 rcu_read_lock(); task =3D pid_task(proc_pid(dir), PIDTYPE_PID); @@ -282,6 +284,12 @@ static struct net *get_proc_task_net(struct inode *dir) } rcu_read_unlock(); =20 + if (net && (fs_info->pidonly =3D=3D PROC_PIDONLY_ON) && + security_capable(fs_info->mounter_cred, net->user_ns, CAP_NET_ADMIN, = CAP_OPT_NONE) < 0) { + put_net(net); + net =3D NULL; + } + return net; } =20 diff --git a/fs/proc/root.c b/fs/proc/root.c index d8ca41d823e4..c4af3a9b1a44 100644 --- a/fs/proc/root.c +++ b/fs/proc/root.c @@ -254,6 +254,7 @@ static int proc_fill_super(struct super_block *s, struc= t fs_context *fc) return -ENOMEM; =20 fs_info->pid_ns =3D get_pid_ns(ctx->pid_ns); + fs_info->mounter_cred =3D get_cred(fc->cred); proc_apply_options(fs_info, fc, current_user_ns()); =20 /* 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; --=20 2.53.0