From patchwork Tue Mar 15 12:48:11 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jose Ignacio Tornos Martinez X-Patchwork-Id: 551575 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 93E4CC433EF for ; Tue, 15 Mar 2022 12:48:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348470AbiCOMtj (ORCPT ); Tue, 15 Mar 2022 08:49:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45930 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235032AbiCOMtg (ORCPT ); Tue, 15 Mar 2022 08:49:36 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id CA55C4AE03 for ; Tue, 15 Mar 2022 05:48:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1647348497; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=qdjFfW4Egu5wJC/60VRjB5Q+2B1Nizx/lGSgqpzqJ78=; b=AHA6LdzEaHiPR0vzNOwM59xIHVB5s6lIvMyz4boW4kl95roegBJ2nkNj7D920HnV4D4OM+ sm52az0fxqxDh8JPEdLRTCDYwj91SLTRF5akSl2M+KfFSKRrhL8pKt75rKmM81OTbRF9Us wQhSqkxciQUtrUIDs2uaZFy5S5CvaeA= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-609-2DtNzB51OGyoMHkyBrvnXQ-1; Tue, 15 Mar 2022 08:48:16 -0400 X-MC-Unique: 2DtNzB51OGyoMHkyBrvnXQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 1C45518E5346; Tue, 15 Mar 2022 12:48:16 +0000 (UTC) Received: from fedora.redhat.com (unknown [10.39.192.181]) by smtp.corp.redhat.com (Postfix) with ESMTP id 26408141ADA5; Tue, 15 Mar 2022 12:48:14 +0000 (UTC) From: Jose Ignacio Tornos Martinez To: johannes@sipsolutions.net, linux-wireless@vger.kernel.org Cc: Jose Ignacio Tornos Martinez Subject: [PATCH] rfkill: keep rfkill event compatibility with old userspace applications Date: Tue, 15 Mar 2022 13:48:11 +0100 Message-Id: <20220315124811.237037-1-jtornosm@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.85 on 10.11.54.7 Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org Old userspace applications (for example bluez version before c939747f543a), that still use the original format for rfkill events (with 8 bytes size / RFKILL_EVENT_SIZE_V1) and are not requesting any specific size but a large one, are broken because they are checking the received size. The reason is the new extended rfkill event format that is used by kernel, if requested size is big enough. Detailed operation of commented bluez versions, by means of strace output: read(11, "\0\0\0\0\2\2\1\0\0", 32) = 9 That is, as the new rfkill event size is 9, it will be rejected by commented bluez versions (expected size 8). In order to avoid this compatibility issue, we can try to adapt by checking specific unusual requested sizes: - bluez: 32 - gnome-settings-daemon: 1024 If this is the case, we will consider that we have to use the original size (RFKILL_EVENT_SIZE_V1) and old applications will be able to work as ever. For other values, we will follow the new behavior with extended events. No other applications have been identified that behave in this way, so reserved event sizes are defined. Fixes: 71826654ce40 ("rfkill: revert back to old userspace API by default") Signed-off-by: Jose Ignacio Tornos Martinez --- include/uapi/linux/rfkill.h | 6 ++++++ net/rfkill/core.c | 8 +++++++- 2 files changed, 13 insertions(+), 1 deletion(-) diff --git a/include/uapi/linux/rfkill.h b/include/uapi/linux/rfkill.h index 9b77cfc42efa..821e304a1d8e 100644 --- a/include/uapi/linux/rfkill.h +++ b/include/uapi/linux/rfkill.h @@ -168,8 +168,14 @@ struct rfkill_event_ext { * older kernel; * 3. treat reads that are as long as requested as acceptable, not * checking against RFKILL_EVENT_SIZE_V1 or such. + * 4. in order to avoid compatibilities issues with older application + * versions specifying unusual event size requests, those unusual + * request event sizes will be considered reserved. If requested size + * is reserved, the event size will be RFKILL_EVENT_SIZE_V1. */ #define RFKILL_EVENT_SIZE_V1 sizeof(struct rfkill_event) +#define RESERVED_RFKILL_EVENT_SIZE_1 32 +#define RESERVED_RFKILL_EVENT_SIZE_2 1024 /* ioctl for turning off rfkill-input (if present) */ #define RFKILL_IOC_MAGIC 'R' diff --git a/net/rfkill/core.c b/net/rfkill/core.c index b73a741a7923..494335d4f5f7 100644 --- a/net/rfkill/core.c +++ b/net/rfkill/core.c @@ -1231,7 +1231,13 @@ static ssize_t rfkill_fop_read(struct file *file, char __user *buf, ev = list_first_entry(&data->events, struct rfkill_int_event, list); - sz = min_t(unsigned long, sizeof(ev->ev), count); + BUILD_BUG_ON(sizeof(ev->ev) == RESERVED_RFKILL_EVENT_SIZE_1 || + sizeof(ev->ev) == RESERVED_RFKILL_EVENT_SIZE_2); + if (count == RESERVED_RFKILL_EVENT_SIZE_1 || + count == RESERVED_RFKILL_EVENT_SIZE_2) + sz = RFKILL_EVENT_SIZE_V1; + else + sz = min_t(unsigned long, sizeof(ev->ev), count); ret = sz; if (copy_to_user(buf, &ev->ev, sz)) ret = -EFAULT;