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Sat, 14 Nov 2026 13:09:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794661788; bh=TzlH4lJ7ZSZIblRm06H21pfwXJAWDZmkD7RxeUrwAwo=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=GlyL6zOy3U34aQUy3eHEQO1vIyJXeAiTdOGtABLlkjbMnvKHjyhKDScl3Hk7rbn/i bUN/hnUMxKho/1WWAiF8JiculAXTejCCuJ3FonfhnSNp937ufCy4qoRmfbGVvZHsH7 9rlf5d2C3SdZVqBTg4J8yIIUsxC5D98LB2FsGhf59wAx6+iIV/zNQO/IKTaGaMPHTI VX46CiB8pXPS+hXzwpsFz2BDETD3xysRH8Rj/RJaz/eTFDnVWydJvu5JEiwzj8rnWQ EWDXUNsiasluJEgOXK7yZCzr+ogHhW+EDBwb4kKVBL61Tujac2yGBy06BywSGLd7Mo Pny//KWEyQopg== From: Christian Brauner Date: Sat, 14 Nov 2026 14:02:17 +0100 Subject: [PATCH RFC v2 36/42] nvmet: refuse files on pseudo filesystems as namespace backing files X-Mailing-List: linux-erofs@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Subscribe: , , Precedence: list X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261114-work-loop-pseudo-v2-36-98639a2286fb@kernel.org> References: <20261114-work-loop-pseudo-v2-0-98639a2286fb@kernel.org> In-Reply-To: <20261114-work-loop-pseudo-v2-0-98639a2286fb@kernel.org> To: 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, "Christian Brauner (Amutable)" X-Mailer: b4 0.17-dev-ce4c1 X-Developer-Signature: v=1; a=openpgp-sha256; l=1428; i=brauner@kernel.org; h=from:subject:message-id; bh=T+p95LnTvG69fzj91gxDjYpoYRzamfjNk16RgT8U7v8=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWT9iOn/sX7W5ofcrzdtZCmXtdsrsyZy06+ylnkxnetWq G9bLL97VkcpC4MYF4OsmCKLQ7tJuNxynorNRpkaMHNYmUCGMHBxCsBElN4x/E+qPMN83LkkV8+9 6emz+TtUM58mNc28vP//+pR517bGGTYz/NOw1Z5h9eBm2/zf+wUFPT6nLXtx+IKQe7yGYPaa6P/ 27ZwA X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 The file backend takes any file that can be opened for reading and writing. With buffered_io=1 that includes files on procfs or sysfs which then get read and written by a kernel worker on behalf of the host. Refuse files on pseudo filesystems just like loop does by switching to file_check_backing(). Note that the helper only accepts regular files and block devices. A block device ends up in the file backend when buffered_io is set. But so far the file backend also took anything else with ->read_iter() and ->write_iter() such as character devices and FIFOs. The size of the namespace is the size of the inode which is zero for all of them. So such a namespace was unusable anyway. Refuse them. Signed-off-by: Christian Brauner (Amutable) --- drivers/nvme/target/io-cmd-file.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/nvme/target/io-cmd-file.c b/drivers/nvme/target/io-cmd-file.c index dfa8aa46188c8..2249ad3bb46d8 100644 --- a/drivers/nvme/target/io-cmd-file.c +++ b/drivers/nvme/target/io-cmd-file.c @@ -47,10 +47,9 @@ int nvmet_file_ns_enable(struct nvmet_ns *ns) return ret; } - if (!ns->file->f_op->read_iter || !ns->file->f_op->write_iter) { - ret = -EINVAL; + ret = file_check_backing(ns->file, FMODE_READ | FMODE_WRITE, S_IFBLK); + if (ret) goto err; - } nvmet_file_ns_revalidate(ns); -- 2.53.0