From patchwork Mon Aug 19 22:56:27 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Guilherme G. Piccoli" X-Patchwork-Id: 13769168 Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) (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 274B73C482; Mon, 19 Aug 2024 22:57:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=178.60.130.6 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724108266; cv=none; b=NS0pd0RLzAXwLoNPMwnN4tkFwALv+RTltyjKe0XsEBJdBja73KFmA2wGyzfxr0ESYt0HQQHDfZbJE+t0I1tOgwx35XnXqoc4+8f6dnVAF4GCXK0bmjVYMOfo23ckHaeSSQWEJQza4pUIwau4857QRggZAcVisTYsFLfWn4zXD7k= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724108266; c=relaxed/simple; bh=3RYkj11lora+jk88iuLfmUrVXzlcGtIcbelB817NQv4=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=rZYyxBJgEjVnLQ0qO/GR88tECafHV+hSMZvRcn8tfYoZ0m+q8kB/PaY9SOjGCuD/46wcm1pOTbUHNjswvWRm1rAZ2svwLjeqnUsmtNHcEaNFLU3PtCzoSwdFDz1ExKFlRR/B3tBA6txkTv7PL8qCLjjjMeQcHC7MNYM26T+2rS0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=igalia.com; spf=pass smtp.mailfrom=igalia.com; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b=ot1hZGON; arc=none smtp.client-ip=178.60.130.6 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=igalia.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=igalia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b="ot1hZGON" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:MIME-Version:Message-ID:Date:Subject: Cc:To:From:Sender:Reply-To:Content-Type:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: In-Reply-To:References:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=iGfyJmX1Qzz8nM0pIFZUr1CNLjNyXjnaY0/FtRYCuzY=; b=ot1hZGONVPSZvQBPNekSSZ6h1b L1c1lvSHOZlXHoDhld0CaHi/GNxXUK7CHiKtcNEW1TFDHUrJbaGy4irle5OEGCQDHrXTSO+CK5gN2 a0xMyaH38iD/d2kKA+X7iO3HrCKfV8hhHC7/inMqtTvEcYt6H/zyMHaFNY5XUNWmtRquWVnK4ZYhp KicX6G55EOvHCSEM9Rez9da2LN3jlllyp9JJpKuMbC9XewXOmSk8l0/5l6hVEZPK9xf76EY14sKCZ wEacaWqalp/l59k5PlBpj3YnNzWtZJL+3bTlU6gxbV0Vuy79SD4k9JWnBkZ/RN7051LIAsW2d4SRj +1NGjhlA==; Received: from [177.76.152.96] (helo=localhost) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1sgBJb-002OXu-UJ; Tue, 20 Aug 2024 00:57:31 +0200 From: "Guilherme G. Piccoli" To: linux-doc@vger.kernel.org Cc: corbet@lwn.net, jack@suse.cz, linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, kernel-dev@igalia.com, kernel@gpiccoli.net, "Guilherme G. Piccoli" Subject: [PATCH] Documentation: Document the kernel flag bdev_allow_write_mounted Date: Mon, 19 Aug 2024 19:56:27 -0300 Message-ID: <20240819225626.2000752-2-gpiccoli@igalia.com> X-Mailer: git-send-email 2.45.2 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Commit ed5cc702d311 ("block: Add config option to not allow writing to mounted devices") added a Kconfig option along with a kernel command-line tuning to control writes to mounted block devices, as a means to deal with fuzzers like Syzkaller, that provokes kernel crashes by directly writing on block devices bypassing the filesystem (so the FS has no awareness and cannot cope with that). The patch just missed adding such kernel command-line option to the kernel documentation, so let's fix that. Signed-off-by: Guilherme G. Piccoli --- Documentation/admin-guide/kernel-parameters.txt | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 09126bb8cc9f..709d1ee342db 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -517,6 +517,16 @@ Format: ,, See header of drivers/net/hamradio/baycom_ser_hdx.c. + bdev_allow_write_mounted= + Format: + Control the ability of directly writing to mounted block + devices' page cache, i.e., allow / disallow writes that + bypasses the FS. This was implemented as a means to + prevent fuzzers to crash the kernel by breaking the + filesystem without its awareness, through direct block + device writes. Default is Y and can be changed through + the Kconfig option CONFIG_BLK_DEV_WRITE_MOUNTED. + bert_disable [ACPI] Disable BERT OS support on buggy BIOSes.