From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=74.125.225.139 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794573425; b=PTEdKT453A67aKjfcx/uyLoXiKuh6HqMl06/1UPGyhDEIX0iq1MZwEIDPjy6jyOxeuHR UTjm0wraXwqY8g4xwkxBhaiYBiCAchpGwxOhBEsRLztI0vsUCXyRoUXYoXGqRd2zwmuQn sHnZok7Gz2hPRr9q5H/4fFxMqAHjaC1Snh5C/KLL2//ad01gG5gnkejM6lRiP3ZFBys2U bK9XaOwNx0kptrmzfqY8X2Rs0NuX2yC4r0jVsorxGSN12AgG0f015eu2T41kEyLu+Nwkn ki6iY1JnrguLDDtxmM8Ncdz5clteaJDztC28l/5oFkmFAiMc13HMEjGjo0SHPJdkDcQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794573425; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Forwarded-Encrypted:X-Gm-Message-State:X-Gm-Gg:X-Received:Received: Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:Content-Transfer-Encoding:User-Agent:MIME-Version; bh=87/Ge5NhXdmtGpcXCLUvnqWpWEAxiW5M6eWOW+m4zUs=; b=dKngg1CbgjIpffUQpdax0FtctVAEjLH9YKol1gK6fswagHLLpEiEu7IHqGITXRhpoOyK U8zeDVs3PX+tbmQdLcg8FRXuvV7m9DhLUIHtSTDPfLRYrGMCVfI1kwsYoNeV56Vw+pwQ5 KoiuJE0vsMPPnCAViWzVJI9vt4vai9myNvOeI8yTwfdicMq8bcoocBL8RlIfTi+b8iFhn GrZ18F59NO1YoP5YyPTvE7XDVU7SvZ+eWlJ9lGLeDEwm9NDCKfUsrllrjUIUH2RsmO0Rc sQDrss+TIQZ5TLlFCi8jQAC4asMXK4E1X6Y4bYmPIvpbME+a/0STAL9otwdy7nAijBQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none header.from=amutable.com; spf=pass smtp.mailfrom=amutable.com; dkim=pass header.d=amutable-com.20260707.gappssmtp.com header.i=@amutable-com.20260707.gappssmtp.com header.a=rsa-sha256 header.s=20260707 header.b=n2XPHptJ; arc=none smtp.remote-ip=74.125.225.139 Received: from mail-wm2-f11.google.com (mail-wm2-f11.google.com [74.125.225.139]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D9059606A330 for ; Fri, 13 Nov 2026 12:37:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org D9059606A330 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=amutable.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=amutable.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=amutable-com.20260707.gappssmtp.com header.i=@amutable-com.20260707.gappssmtp.com header.a=rsa-sha256 header.s=20260707 header.b=n2XPHptJ Received: by mail-wm2-f11.google.com with SMTP id 5b1f17b1804b1-4a5f76661b5so3542065e9.0 for ; Fri, 13 Nov 2026 04:37:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amutable-com.20260707.gappssmtp.com; s=20260707; t=1794573423; x=1795178223; darn=vger.kernel.org; h=mime-version:user-agent:content-transfer-encoding:content-type :references:in-reply-to:date:cc:to:from:subject:message-id:from:to :cc:subject:date:message-id:reply-to:content-type; bh=87/Ge5NhXdmtGpcXCLUvnqWpWEAxiW5M6eWOW+m4zUs=; b=n2XPHptJWAiGnWBjuWK6g5NkFljgiKFcabC8Vn0J/U7Rs5oCxIs8ae//bm8icbKFtW GhaGag1Xoi7ZyXwdHESo4gzqQGVIFHJ4SWyDVffZrMrzihrR6J8Y41NroO1pUm4S3UEM GevRMV87lpSFNCzDE68IInZGbL5X+gYDk7IApotAPKeUo9xOfBbHGBSC5mcggp0KJBcK Nc+e1mR1SmgmgC0Frha4Bk72pKDTzd14yUseYASwtvG8qZfbG+gNn4GmoQhA8ODET64L X6SskqZIriPJvj35d5mhI8G8hobVKdLKjnxeG6bMHAYcCPTjUD9dRkaaJK3nWVTXV/IA bDIw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1794573423; x=1795178223; h=mime-version:user-agent:content-transfer-encoding:content-type :references:in-reply-to:date:cc:to:from:subject:message-id:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=87/Ge5NhXdmtGpcXCLUvnqWpWEAxiW5M6eWOW+m4zUs=; b=kvd1gqh1QUBfUHA2Ap93t7c1F019qYlkwBbJQ5qoNxBQRtQnBKboaWAoVrY74xrpOR DoUheIESgH1HpKrP3+uSj3kmgl9g4CsaHVBWXY2zr3+O2uB0Max+SQMAiZM95o5SlCDv Fz3jFiy/Rkc7jQYrqQQfH7sf3P8BP6NYRqiFsFL2fCqcYBTS9J+1uil9X8Py1LmG//ja LAugATAPFueqVM2xlg5sPQGBTyadWZ5UfaluicHQyQgJCGZCuJn+QAHHSyVpakdvuxG2 JliRRfnM9S7t8gnIO3j4zINrXZxBLRgauRKi9r9t6dHrJAOXoWf579vxraVCQsdaUsu1 JowA== X-Forwarded-Encrypted: i=1; AL+hErFe7hZSbhdyq1rYeH84qDv4P4OpkUMvvR+dYY05G5FRbMNm6Wa6UgoIAaYxyObRarhJk4jjYxUrgxI=@vger.kernel.org X-Gm-Message-State: APuU4Z+7aZlzgk3zie8cR/XjzXUczQ0Nq4vfWyGXxZRkG3NFVY4OQBZ+ HREQIuFLyuyRmgIV3KXO2PWjm/y1BAQAWI7kAuYv2F9UtCGCS2EGpleIdYGmanX0JRUs X-Gm-Gg: AYBFou2RAiz2FVXXlaMYTCqegW0i1+fSojixtAdEgt7JEaqO4FwTKc2VRfW4UFuqMBS 3TvarWIHDIvttKf0yVFf9aWWJBGiBa1XLhSlkSY+S3zkDZzMp+mwawKcy0yvwQnrlfPsqB5PYdu lFfk6bk3r5af+n0ehN+O4uQD7W5hDXMUbdtIUCqo3nCsQxm2PJGr9in+W83DJNnurfdyygAP9RU vDZyZKr08slN0ZiEdJ1Zi+a79APxMDYKql8djrb8R2ymmm7ynSjDiawx13n66O68YTd1wD4el5M xA6eg36JjHYcpPLwq8XJw5CXImzk+pRCeaMW3BkNg1Pvo4jzTDgMsuAm07XmzqoLxx8WPReYv++ BVlVVYGrHys5mob0WWhgqrF2bG66EDCw0BNCz788aVT8S8suG3jaYhBqFWu5X/KEkglYNej4FGA F1dLLld6+rCawoVfUxOUtusDNIKIEMDsBI9cZTlKgUs8QQQusF7+R81oevnUJ7Sxvslv9G8xoLw HpowQhd2OVM18c+N42CuIWnRdkLz2Dbb+oKPJncENIGaFN6eec5jdCHMWysK+ZmofLBy2BKSgeZ 9KL/iA5maTWkv6hvUTdCp6qzOpvsP449uumDynlEF9fVIwJroypeB6IcfQ/Qs6TiqEowzkGxgjM 3q9aRwO80 X-Received: by 2002:a05:600c:b86:b0:4b5:d95c:2378 with SMTP id 5b1f17b1804b1-4bb55ac4030mr49782945e9.34.1794573423157; Fri, 13 Nov 2026 04:37:03 -0800 (PST) Received: from [10.0.0.233] (tmo-086-54.customers.d1-online.com. [80.187.86.54]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4bb55af2901sm57437255e9.13.2026.11.13.04.37.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Nov 2026 04:37:02 -0800 (PST) Message-ID: Subject: Re: [PATCH RFC 39/41] usb: gadget: f_mass_storage: refuse files on pseudo filesystems From: Alexander Mikhalitsyn To: Christian Brauner , linux-fsdevel@vger.kernel.org Cc: Jann Horn , Chris Mason , Josef Bacik , Christoph Hellwig , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, Alexander Viro , Jan Kara , linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, driver-core@lists.linux.dev, linux-mm@kvack.org, bpf@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, apparmor@lists.ubuntu.com, linux-nfs@vger.kernel.org, netdev@vger.kernel.org, fuse-devel@lists.linux.dev, linux-efi@vger.kernel.org, xen-devel@lists.xenproject.org, ocfs2-devel@lists.linux.dev, linux-s390@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-usb@vger.kernel.org, Amir Goldstein , linux-erofs@lists.ozlabs.org, linux-kselftest@vger.kernel.org Date: Fri, 13 Nov 2026 13:36:59 +0100 In-Reply-To: <20261110-work-loop-pseudo-v1-39-4c998976c6c7@kernel.org> References: <20261110-work-loop-pseudo-v1-0-4c998976c6c7@kernel.org> <20261110-work-loop-pseudo-v1-39-4c998976c6c7@kernel.org> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.2-0+deb13u1 X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 On Tue, 2026-11-10 at 10:14 +0100, Christian Brauner wrote: > fsg_lun_open() takes any regular file as the backing file of a LUN. > The > file-storage kthread then reads and writes it with kernel_read() and > kernel_write() on behalf of the USB host. With a procfs or sysfs file > behind a LUN the host gets to read and write kernel interfaces with > kernel credentials. Refuse files on pseudo filesystems just like loop > does. >=20 > Signed-off-by: Christian Brauner (Amutable) Reviewed-by: Alexander Mikhalitsyn > --- > =C2=A0drivers/usb/gadget/function/storage_common.c | 5 +++++ > =C2=A01 file changed, 5 insertions(+) >=20 > diff --git a/drivers/usb/gadget/function/storage_common.c > b/drivers/usb/gadget/function/storage_common.c > index 75831f2c7abe..83683ade20c2 100644 > --- a/drivers/usb/gadget/function/storage_common.c > +++ b/drivers/usb/gadget/function/storage_common.c > @@ -211,6 +211,11 @@ int fsg_lun_open(struct fsg_lun *curlun, const > char *filename) > =C2=A0 goto out; > =C2=A0 } > =C2=A0 > + if (file_is_pseudo(filp)) { > + LINFO(curlun, "file on a pseudo filesystem: %s\n", > filename); > + goto out; > + } > + > =C2=A0 /* > =C2=A0 * If we can't read the file, it's no good. > =C2=A0 * If we can't write the file, use it read-only.