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=-5.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 1D209C2D0C9 for ; Sat, 14 Dec 2019 17:56:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D0F86207FD for ; Sat, 14 Dec 2019 17:56:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="KTa/A2vD" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727181AbfLNR4j (ORCPT ); Sat, 14 Dec 2019 12:56:39 -0500 Received: from mail-lf1-f67.google.com ([209.85.167.67]:32876 "EHLO mail-lf1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726792AbfLNR4j (ORCPT ); Sat, 14 Dec 2019 12:56:39 -0500 Received: by mail-lf1-f67.google.com with SMTP id n25so1506988lfl.0; Sat, 14 Dec 2019 09:56:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:autocrypt:message-id:date:user-agent :mime-version:in-reply-to; bh=Fa8lw02ivhbwAMD/0kKb4b8FWTP4Fni72JISw89p08E=; b=KTa/A2vD2Upgn3m+UwRD3/KqhsjhdnZTWGijuOeGaKM7zEvS4zHZhoxT88SUJpvSAM coSZM7fMn8U4Ve2ZV3WUUTekuQvLhEc8xfXOs105/YWxPvILEG+GoeUcpnKTDWChVtsH 0vJxXemQY2w6xO+Acqnb4aYAvVBMs4Yt7x47iAlsU2QCnLot0UbScFWQ0sXJO1kyvH/D eN2VUOxAM1DewzjApZBtXIAzGAHdP5rtYAVJ3MtksC7BEo3QyIpCFSVrHq0uDpRebwom RUCE8cGqDHwHHhi2c6gKn6G5BtutkW7nbhRfTm38mnplBbLdx7pfUY6VzWylTCJmNfsD bAQg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:autocrypt :message-id:date:user-agent:mime-version:in-reply-to; bh=Fa8lw02ivhbwAMD/0kKb4b8FWTP4Fni72JISw89p08E=; b=qLJ2dSyYF/l5KdGyjt7rzuAZNBG6ebZFhBcRzwvG1B/aVMX2G6EiBVWxhpX4xzmvaB cY8AONtnanmlONEXmZ5OAjp4v+kilp/xlX63I8FHle57lOiKDyb7ia/5dNcy97IDJJH8 ws/M88OwQ8IRL8SKgt4Zah3jNoI9HsfUdavfSNJMpFpn/EbMLxWZnkmyEth0ZVYtQjad UnIWYZOpMKOYLNw43bt1cPgyJr8QGKVuwZp9cHzqKoPe81iu5LCrgyd6UvT4Mf3xE5xb 26Dd8GdRJ6cTTwZm1PDBwBUa8q3wZhEOm5pd/Y4wme6J1w+ndWahspWiEb598L/1C71b BvuQ== X-Gm-Message-State: APjAAAXeJyxYizzmweqjmatxViweVRuU0Qb2dpIH+1ySWckAJgEidDwX KQql+lhUxEt7EjGwSjJLbmOkKlJL87k= X-Google-Smtp-Source: APXvYqznIvGNCl59IIk8njEjrcNTb18ZdErSx6ZEHF8I+tJgTQBfysa8ANH0HLN72dh8aOAs7SvW+w== X-Received: by 2002:a19:5007:: with SMTP id e7mr12186382lfb.153.1576346196178; Sat, 14 Dec 2019 09:56:36 -0800 (PST) Received: from [192.168.1.66] (88-119-143-153.static.zebra.lt. [88.119.143.153]) by smtp.gmail.com with ESMTPSA id 22sm7976110ljw.9.2019.12.14.09.56.34 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 14 Dec 2019 09:56:35 -0800 (PST) Subject: Re: [RFC PATCH] io_uring: add support for IORING_OP_IOCTL To: Jann Horn Cc: Jens Axboe , io-uring , kernel list References: From: Pavel Begunkov Autocrypt: addr=asml.silence@gmail.com; prefer-encrypt=mutual; keydata= mQINBFmKBOQBEAC76ZFxLAKpDw0bKQ8CEiYJRGn8MHTUhURL02/7n1t0HkKQx2K1fCXClbps bdwSHrhOWdW61pmfMbDYbTj6ZvGRvhoLWfGkzujB2wjNcbNTXIoOzJEGISHaPf6E2IQx1ik9 6uqVkK1OMb7qRvKH0i7HYP4WJzYbEWVyLiAxUj611mC9tgd73oqZ2pLYzGTqF2j6a/obaqha +hXuWTvpDQXqcOZJXIW43atprH03G1tQs7VwR21Q1eq6Yvy2ESLdc38EqCszBfQRMmKy+cfp W3U9Mb1w0L680pXrONcnlDBCN7/sghGeMHjGKfNANjPc+0hzz3rApPxpoE7HC1uRiwC4et83 CKnncH1l7zgeBT9Oa3qEiBlaa1ZCBqrA4dY+z5fWJYjMpwI1SNp37RtF8fKXbKQg+JuUjAa9 Y6oXeyEvDHMyJYMcinl6xCqCBAXPHnHmawkMMgjr3BBRzODmMr+CPVvnYe7BFYfoajzqzq+h EyXSl3aBf0IDPTqSUrhbmjj5OEOYgRW5p+mdYtY1cXeK8copmd+fd/eTkghok5li58AojCba jRjp7zVOLOjDlpxxiKhuFmpV4yWNh5JJaTbwCRSd04sCcDNlJj+TehTr+o1QiORzc2t+N5iJ NbILft19Izdn8U39T5oWiynqa1qCLgbuFtnYx1HlUq/HvAm+kwARAQABtDFQYXZlbCBCZWd1 bmtvdiAoc2lsZW5jZSkgPGFzbWwuc2lsZW5jZUBnbWFpbC5jb20+iQJOBBMBCAA4FiEE+6Ju PTjTbx479o3OWt5b1Glr+6UFAlmKBOQCGwMFCwkIBwIGFQgJCgsCBBYCAwECHgECF4AACgkQ Wt5b1Glr+6WxZA//QueaKHzgdnOikJ7NA/Vq8FmhRlwgtP0+E+w93kL+ZGLzS/cUCIjn2f4Q Mcutj2Neg0CcYPX3b2nJiKr5Vn0rjJ/suiaOa1h1KzyNTOmxnsqE5fmxOf6C6x+NKE18I5Jy xzLQoktbdDVA7JfB1itt6iWSNoOTVcvFyvfe5ggy6FSCcP+m1RlR58XxVLH+qlAvxxOeEr/e aQfUzrs7gqdSd9zQGEZo0jtuBiB7k98t9y0oC9Jz0PJdvaj1NZUgtXG9pEtww3LdeXP/TkFl HBSxVflzeoFaj4UAuy8+uve7ya/ECNCc8kk0VYaEjoVrzJcYdKP583iRhOLlZA6HEmn/+Gh9 4orG67HNiJlbFiW3whxGizWsrtFNLsSP1YrEReYk9j1SoUHHzsu+ZtNfKuHIhK0sU07G1OPN 2rDLlzUWR9Jc22INAkhVHOogOcc5ajMGhgWcBJMLCoi219HlX69LIDu3Y34uIg9QPZIC2jwr 24W0kxmK6avJr7+n4o8m6sOJvhlumSp5TSNhRiKvAHB1I2JB8Q1yZCIPzx+w1ALxuoWiCdwV M/azguU42R17IuBzK0S3hPjXpEi2sK/k4pEPnHVUv9Cu09HCNnd6BRfFGjo8M9kZvw360gC1 reeMdqGjwQ68o9x0R7NBRrtUOh48TDLXCANAg97wjPoy37dQE7e5Ag0EWYoE5AEQAMWS+aBV IJtCjwtfCOV98NamFpDEjBMrCAfLm7wZlmXy5I6o7nzzCxEw06P2rhzp1hIqkaab1kHySU7g dkpjmQ7Jjlrf6KdMP87mC/Hx4+zgVCkTQCKkIxNE76Ff3O9uTvkWCspSh9J0qPYyCaVta2D1 Sq5HZ8WFcap71iVO1f2/FEHKJNz/YTSOS/W7dxJdXl2eoj3gYX2UZNfoaVv8OXKaWslZlgqN jSg9wsTv1K73AnQKt4fFhscN9YFxhtgD/SQuOldE5Ws4UlJoaFX/yCoJL3ky2kC0WFngzwRF Yo6u/KON/o28yyP+alYRMBrN0Dm60FuVSIFafSqXoJTIjSZ6olbEoT0u17Rag8BxnxryMrgR dkccq272MaSS0eOC9K2rtvxzddohRFPcy/8bkX+t2iukTDz75KSTKO+chce62Xxdg62dpkZX xK+HeDCZ7gRNZvAbDETr6XI63hPKi891GeZqvqQVYR8e+V2725w+H1iv3THiB1tx4L2bXZDI DtMKQ5D2RvCHNdPNcZeldEoJwKoA60yg6tuUquvsLvfCwtrmVI2rL2djYxRfGNmFMrUDN1Xq F3xozA91q3iZd9OYi9G+M/OA01husBdcIzj1hu0aL+MGg4Gqk6XwjoSxVd4YT41kTU7Kk+/I 5/Nf+i88ULt6HanBYcY/+Daeo/XFABEBAAGJAjYEGAEIACAWIQT7om49ONNvHjv2jc5a3lvU aWv7pQUCWYoE5AIbDAAKCRBa3lvUaWv7pfmcEACKTRQ28b1y5ztKuLdLr79+T+LwZKHjX++P 4wKjEOECCcB6KCv3hP+J2GCXDOPZvdg/ZYZafqP68Yy8AZqkfa4qPYHmIdpODtRzZSL48kM8 LRzV8Rl7J3ItvzdBRxf4T/Zseu5U6ELiQdCUkPGsJcPIJkgPjO2ROG/ZtYa9DvnShNWPlp+R uPwPccEQPWO/NP4fJl2zwC6byjljZhW5kxYswGMLBwb5cDUZAisIukyAa8Xshdan6C2RZcNs rB3L7vsg/R8UCehxOH0C+NypG2GqjVejNZsc7bgV49EOVltS+GmGyY+moIzxsuLmT93rqyII 5rSbbcTLe6KBYcs24XEoo49Zm9oDA3jYvNpeYD8rDcnNbuZh9kTgBwFN41JHOPv0W2FEEWqe JsCwQdcOQ56rtezdCJUYmRAt3BsfjN3Jn3N6rpodi4Dkdli8HylM5iq4ooeb5VkQ7UZxbCWt UVMKkOCdFhutRmYp0mbv2e87IK4erwNHQRkHUkzbsuym8RVpAZbLzLPIYK/J3RTErL6Z99N2 m3J6pjwSJY/zNwuFPs9zGEnRO4g0BUbwGdbuvDzaq6/3OJLKohr5eLXNU3JkT+3HezydWm3W OPhauth7W0db74Qd49HXK0xe/aPrK+Cp+kU1HRactyNtF8jZQbhMCC8vMGukZtWaAwpjWiiH bA== Message-ID: <9b4f56c1-dce9-1acd-2775-e64a3955d8ee@gmail.com> Date: Sat, 14 Dec 2019 20:56:12 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="4YB4m92gfg19Nx3WrZ9JrMujaIA3FhllQ" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --4YB4m92gfg19Nx3WrZ9JrMujaIA3FhllQ Content-Type: multipart/mixed; boundary="sNXDW8RANKm4Uql8TTvlqedYda3jQiFlf"; protected-headers="v1" From: Pavel Begunkov To: Jann Horn Cc: Jens Axboe , io-uring , kernel list Message-ID: <9b4f56c1-dce9-1acd-2775-e64a3955d8ee@gmail.com> Subject: Re: [RFC PATCH] io_uring: add support for IORING_OP_IOCTL References: In-Reply-To: --sNXDW8RANKm4Uql8TTvlqedYda3jQiFlf Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 14/12/2019 20:12, Jann Horn wrote: > On Sat, Dec 14, 2019 at 4:30 PM Pavel Begunkov = wrote: >> This works almost like ioctl(2), except it doesn't support a bunch of >> common opcodes, (e.g. FIOCLEX and FIBMAP, see ioctl.c), and goes >> straight to a device specific implementation. >> >> The case in mind is dma-buf, drm and other ioctl-centric interfaces. >> >> Not-yet Signed-off-by: Pavel Begunkov >> --- >> >> It clearly needs some testing first, though works fine with dma-buf, >> but I'd like to discuss whether the use cases are convincing enough, >> and is it ok to desert some ioctl opcodes. For the last point it's >> fairly easy to add, maybe except three requiring fd (e.g. FIOCLEX) >> >> P.S. Probably, it won't benefit enough to consider using io_uring >> in drm/mesa, but anyway. > [...] >> +static int io_ioctl(struct io_kiocb *req, >> + struct io_kiocb **nxt, bool force_nonblock) >> +{ >> + const struct io_uring_sqe *sqe =3D req->sqe; >> + unsigned int cmd =3D READ_ONCE(sqe->ioctl_cmd); >> + unsigned long arg =3D READ_ONCE(sqe->ioctl_arg); >> + int ret; >> + >> + if (!req->file) >> + return -EBADF; >> + if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL)) >> + return -EINVAL; >> + if (unlikely(sqe->ioprio || sqe->addr || sqe->buf_index >> + || sqe->rw_flags)) >> + return -EINVAL; >> + if (force_nonblock) >> + return -EAGAIN; >> + >> + ret =3D security_file_ioctl(req->file, cmd, arg); >> + if (!ret) >> + ret =3D (int)vfs_ioctl(req->file, cmd, arg); >=20 > This isn't going to work. For several of the syscalls that were added, > special care had to be taken to avoid bugs - like for RECVMSG, for the > upcoming OPEN/CLOSE stuff, and so on. >=20 > And in principle, ioctls handlers can do pretty much all of the things > syscalls can do, and more. They can look at the caller's PID, they can > open and close (well, technically that's slightly unsafe, but IIRC > autofs does it anyway) things in the file descriptor table, they can > give another process access to the calling process in some way, and so > on. If you just allow calling arbitrary ioctls through io_uring, you > will certainly get bugs, and probably security bugs, too. >=20 > Therefore, I would prefer to see this not happen at all; and if you do > have a usecase where you think the complexity is worth it, then I > think you'll have to add new infrastructure that allows each > file_operations instance to opt in to having specific ioctls called > via this mechanism, or something like that, and ensure that each of > the exposed ioctls only performs operations that are safe from uring > worker context. Sounds like hell of a problem. Thanks for sorting this out! >=20 > Also, I'm not sure, but it might be a good idea to CC linux-api if you > continue working on this. >=20 --=20 Pavel Begunkov --sNXDW8RANKm4Uql8TTvlqedYda3jQiFlf-- --4YB4m92gfg19Nx3WrZ9JrMujaIA3FhllQ Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEE+6JuPTjTbx479o3OWt5b1Glr+6UFAl31IkAACgkQWt5b1Glr +6Wx0xAApGN9Sj0cskefxpiPHW2GqjOD9alNmMPvEZxEtN3uZ6RFpdqWosyRKzPj 6MY8PUr8CyELb9K+kVPba5Z2Pm7AFYzNO8fPM9PyoRLaYS0Y+6dCZqsc+RnH6iPj iIuPuiSTFSipbbguQqXF90EbFlHQqLpDjZm2c5zKZXe7pE+H0c6Kz590rbpT0LUh rnyExBS3eL/WoB0CX9ICYWe78c8x+RF2b4c79l6UwzkqmTY1PtZ4DPKbnNJK8kwj Z/u5nGTS2FBZO/TYOrbxhzr26pLykBY8bGlGNlfgmHRQqy23yUngnliE4KD7gWh3 SAVyfOpT6ma8WvhReKfN2AtPM7Ci3c+3ff+/Cd+yBtjK6iN2JHZnYzYdMNwIywwc gEFu8Y7Wolvt3kGm/BGSGAAEMVQrVOCkbJDrTUofltJCA5+dhr7sDTJfFLT7Gs2p puGbN/Ga7+aLgrECUSDW5/s6lcrQRJt1zTvl2vuyJw/OX/Yiu9OM8VHmIVtu0ivP d5JJOHBcmEOxvdwPe7ETyc02FtPSSd4AUVgmVvOOkiDO30LKHaRPkqin6n0cmOi0 NQJHp9cB3Mr9CqC0K5slpq+yfWDzR4FI9oa+zqzCvh61YYvifXukXWCWgSjnSTS/ r7c99Xk9QWfoyadt3O1WDGT1MpNdmlb3MnmntXXHRmD8wCWuXoM= =80hD -----END PGP SIGNATURE----- --4YB4m92gfg19Nx3WrZ9JrMujaIA3FhllQ--