From patchwork Tue Jun 27 12:00:58 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matteo Rizzo X-Patchwork-Id: 13294401 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 19C8FEB64DC for ; Tue, 27 Jun 2023 12:01:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231721AbjF0MB0 (ORCPT ); Tue, 27 Jun 2023 08:01:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59686 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231706AbjF0MBY (ORCPT ); Tue, 27 Jun 2023 08:01:24 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 34CF310FC for ; Tue, 27 Jun 2023 05:01:23 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id 3f1490d57ef6-bb2fae9b286so5694023276.3 for ; Tue, 27 Jun 2023 05:01:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1687867282; x=1690459282; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=aaVuD3HLMj8uVbz/Ei0maxQ5eITeDBVSdg3CAcaaAvU=; b=kWkGxNzo2pBixoyXLjeBlNREEZXwBCBrQkkxw3LBQXZslL74w4595Y1T8H6Y4fGF37 gVj6eV1QM9Tn6NBp7lOUTVtHB7hG9Qo1AOEF6cHubSiBN+m6nle/C/NpMU7L2WiOSoqg pWI+6xnRg8sdTTKj9fM6ZlbSF1HCKydnWC/jhgE1zPYNNc6FgIm3WxVzV77BtATuPm4+ yP/TxIi67DxgjMQPgFgpu71sc1Ag2dfOQudP+leqG4SUeoyvWjmY6sa/1wzI+9/hMqZq MoY5c3XlfgYdc9wpFxPE256L2duZl/qgFHKjdzBxVP+BWAJW7T5zzS8fl7iSxmBDuOvV 9XbA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1687867282; x=1690459282; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=aaVuD3HLMj8uVbz/Ei0maxQ5eITeDBVSdg3CAcaaAvU=; b=f9pNuzY/suNidQR4GREteg68xhUGqwgLUjv0QB6KIXsNVttqm8EAvWUyyUA7Ks4WcW hAts0iPWe3EvcNmWxzmWi+TVGxQTxm2B3uxHQi/9tQZeWkeX7uGUOueiDrqWEX0SeGSv xHp60NulOZfAYBMAuaShnC+wxzZhqFi+P8nkMxXbIsMF3dLC8yg5grNsnEMcKTfNr+fR toLxlXVd2uHdY5WlVummlCVrnlxIe2MqKbDcy+GfibM+aUV9I3vTpDC4Wm8XHB7bNR1r oB7h8U2OhOKbipVmayP6p8MDNf0phR7ENAFLnWaXTACYGSvBDpRZJpAghjRMwduJ8vl/ NcNg== X-Gm-Message-State: AC+VfDxgblDeSPaGKrxm+EYuFB+cZj9wBFvxVkJmRDH15T4oFarwLnUh 7+6c5v6nFTXmcTBOEtNGguwjkJAMA0Z5nxf5DA== X-Google-Smtp-Source: ACHHUZ65QqiqGazk/uIR4xUfnSeMbaVtHXrDciJN6Rf4o768ey3Qm+Gwm3vfwudGVR+45MdhS2x22Oqf2oMizUPbpA== X-Received: from mr-cloudtop2.c.googlers.com ([fda3:e722:ac3:cc00:31:98fb:c0a8:fb5]) (user=matteorizzo job=sendgmr) by 2002:a25:e0d1:0:b0:c2a:e79a:fc11 with SMTP id x200-20020a25e0d1000000b00c2ae79afc11mr1049539ybg.9.1687867282457; Tue, 27 Jun 2023 05:01:22 -0700 (PDT) Date: Tue, 27 Jun 2023 12:00:58 +0000 In-Reply-To: <20230627120058.2214509-1-matteorizzo@google.com> Mime-Version: 1.0 References: <20230627120058.2214509-1-matteorizzo@google.com> X-Mailer: git-send-email 2.41.0.162.gfafddb0af9-goog Message-ID: <20230627120058.2214509-2-matteorizzo@google.com> Subject: [PATCH 1/1] Add a new sysctl to disable io_uring system-wide From: Matteo Rizzo To: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, io-uring@vger.kernel.org Cc: matteorizzo@google.com, jordyzomer@google.com, evn@google.com, poprdi@google.com, corbet@lwn.net, axboe@kernel.dk, asml.silence@gmail.com, akpm@linux-foundation.org, keescook@chromium.org, rostedt@goodmis.org, dave.hansen@linux.intel.com, ribalda@chromium.org, chenhuacai@kernel.org, steve@sk2.org, gpiccoli@igalia.com, ldufour@linux.ibm.com Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Introduce a new sysctl (io_uring_disabled) which can be either 0 or 1. When 0 (the default), all processes are allowed to create io_uring instances, which is the current behavior. When 1, all calls to io_uring_setup fail with -EPERM. Signed-off-by: Matteo Rizzo --- Documentation/admin-guide/sysctl/kernel.rst | 14 ++++++++++++ io_uring/io_uring.c | 24 +++++++++++++++++++++ 2 files changed, 38 insertions(+) diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index d85d90f5d000..3c53a238332a 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -450,6 +450,20 @@ this allows system administrators to override the ``IA64_THREAD_UAC_NOPRINT`` ``prctl`` and avoid logs being flooded. +io_uring_disabled +========================= + +Prevents all processes from creating new io_uring instances. Enabling this +shrinks the kernel's attack surface. + += ============================================================= +0 All processes can create io_uring instances as normal. This is the default + setting. +1 io_uring is disabled. io_uring_setup always fails with -EPERM. Existing + io_uring instances can still be used. += ============================================================= + + kexec_load_disabled =================== diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 1b53a2ab0a27..0496ae7017f7 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -153,6 +153,22 @@ static __cold void io_fallback_tw(struct io_uring_task *tctx); struct kmem_cache *req_cachep; +static int __read_mostly sysctl_io_uring_disabled; +#ifdef CONFIG_SYSCTL +static struct ctl_table kernel_io_uring_disabled_table[] = { + { + .procname = "io_uring_disabled", + .data = &sysctl_io_uring_disabled, + .maxlen = sizeof(sysctl_io_uring_disabled), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE, + }, + {}, +}; +#endif + struct sock *io_uring_get_socket(struct file *file) { #if defined(CONFIG_UNIX) @@ -4003,6 +4019,9 @@ static long io_uring_setup(u32 entries, struct io_uring_params __user *params) SYSCALL_DEFINE2(io_uring_setup, u32, entries, struct io_uring_params __user *, params) { + if (sysctl_io_uring_disabled) + return -EPERM; + return io_uring_setup(entries, params); } @@ -4577,6 +4596,11 @@ static int __init io_uring_init(void) req_cachep = KMEM_CACHE(io_kiocb, SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT | SLAB_TYPESAFE_BY_RCU); + +#ifdef CONFIG_SYSCTL + register_sysctl_init("kernel", kernel_io_uring_disabled_table); +#endif + return 0; }; __initcall(io_uring_init);