From patchwork Mon Jan 21 20:14:55 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roman Penyaev X-Patchwork-Id: 10774491 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 51B4D91E for ; Mon, 21 Jan 2019 20:15:40 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4315B2A9D0 for ; Mon, 21 Jan 2019 20:15:40 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 379F22A9B9; Mon, 21 Jan 2019 20:15:40 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C76372A9C7 for ; Mon, 21 Jan 2019 20:15:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728432AbfAUUPi (ORCPT ); Mon, 21 Jan 2019 15:15:38 -0500 Received: from mx2.suse.de ([195.135.220.15]:55614 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728315AbfAUUPS (ORCPT ); Mon, 21 Jan 2019 15:15:18 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 6A31AAFFE; Mon, 21 Jan 2019 20:15:17 +0000 (UTC) From: Roman Penyaev Cc: Roman Penyaev , Andrew Morton , Davidlohr Bueso , Jason Baron , Al Viro , "Paul E. McKenney" , Linus Torvalds , Andrea Parri , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH v2 12/13] epoll: support mapping for epfd when polled from userspace Date: Mon, 21 Jan 2019 21:14:55 +0100 Message-Id: <20190121201456.28338-13-rpenyaev@suse.de> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190121201456.28338-1-rpenyaev@suse.de> References: <20190121201456.28338-1-rpenyaev@suse.de> MIME-Version: 1.0 To: unlisted-recipients:; (no To-header on input) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP User has to mmap user_header and user_index vmalloce'd pointers in order to consume events from userspace. Also we do not let any copies of vma on fork(). Signed-off-by: Roman Penyaev Cc: Andrew Morton Cc: Davidlohr Bueso Cc: Jason Baron Cc: Al Viro Cc: "Paul E. McKenney" Cc: Linus Torvalds Cc: Andrea Parri Cc: linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- fs/eventpoll.c | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/fs/eventpoll.c b/fs/eventpoll.c index e70d1ab64ec1..cceeff77bdaf 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -1276,11 +1276,47 @@ static void ep_show_fdinfo(struct seq_file *m, struct file *f) } #endif +static int ep_eventpoll_mmap(struct file *filep, struct vm_area_struct *vma) +{ + struct eventpoll *ep = vma->vm_file->private_data; + size_t size; + int rc; + + if (!ep_polled_by_user(ep)) + return -ENOTSUPP; + + size = vma->vm_end - vma->vm_start; + if (!vma->vm_pgoff && size > ep->header_length) + return -ENXIO; + if (vma->vm_pgoff && ep->header_length != (vma->vm_pgoff << PAGE_SHIFT)) + /* Index ring starts exactly after the header */ + return -ENXIO; + if (vma->vm_pgoff && size > ep->index_length) + return -ENXIO; + + /* + * vm_pgoff is used *only* for indication, what is mapped: user header + * or user index ring. Sizes are checked above. + */ + if (!vma->vm_pgoff) + rc = remap_vmalloc_range_partial(vma, vma->vm_start, + ep->user_header, size); + else + rc = remap_vmalloc_range_partial(vma, vma->vm_start, + ep->user_index, size); + if (likely(!rc)) + /* No copies for forks(), please */ + vma->vm_flags |= VM_DONTCOPY; + + return rc; +} + /* File callbacks that implement the eventpoll file behaviour */ static const struct file_operations eventpoll_fops = { #ifdef CONFIG_PROC_FS .show_fdinfo = ep_show_fdinfo, #endif + .mmap = ep_eventpoll_mmap, .release = ep_eventpoll_release, .poll = ep_eventpoll_poll, .llseek = noop_llseek,