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[130.117.225.111]) by mx.google.com with ESMTPS id ffacd0b85a97d-48e3ed1bc40si21900621f8f.398.2026.10.28.02.35.39 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Oct 2026 02:35:39 -0700 (PDT) Received-SPF: pass (google.com: domain of alexander.ivanov@virtuozzo.com designates 130.117.225.111 as permitted sender) client-ip=130.117.225.111; Authentication-Results: mx.google.com; dkim=pass header.i=@virtuozzo.com header.s=relay header.b="I7/Mzfcr"; spf=pass (google.com: domain of alexander.ivanov@virtuozzo.com designates 130.117.225.111 as permitted sender) smtp.mailfrom=alexander.ivanov@virtuozzo.com; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=virtuozzo.com DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=virtuozzo.com; s=relay; h=MIME-Version:Message-ID:Date:Subject:From: Content-Type; bh=Xyiu8btRjpn3coyj2dadwVh15QC8kGBJTkEmEX45x/Q=; b=I7/MzfcrXoCr O3kkUZnnBgrl5APtk/KIbTI5W5pCtq0D1KxfF2NJ7J52WcPGBnxFGnzRiYi88/DBLsg5Q6gNJYXt+ uLFH9w7p7i7LbZfTgvwupXxoSkJPSy3u8/WRsIur+c0z9Y5hiBlqRGPwRXOKfPSqZ3B+9smqnjph3 PT1t8qTfk12DDtttU3ugAmAmuMjOIu7FXrsnvxB3smYGPEP/cmXsOF2H1E0YB/cfK0xQfmrz4KMTg TzSir0dssyRe8elvNsF4tE6WNczya+WOOUB41BlbX/4D9+m5LJ7ukZCFIvkO4pGsngAHMmVQMbgAj D/FhRSJf/U/VKkJiUH8urw==; Received: from ch-vpn.virtuozzo.com ([130.117.225.6] helo=sky) by relay.virtuozzo.com with esmtps (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1xM00X-003VSD-1m; Wed, 28 Oct 2026 10:35:39 +0100 From: Alexander Ivanov To: andrey.zhadchenko@virtuozzo.com Date: Wed, 28 Oct 2026 10:35:36 +0100 Message-ID: <20261028093536.3072110-1-alexander.ivanov@virtuozzo.com> X-Mailer: git-send-email 2.53.0 MIME-Version: 1.0 X-OZ-Fwd: true Cc: devel@openvz.org Subject: [Devel] [PATCH hci-8.1] drivers/vhost/blk: fail guest writes to a read-only backend X-BeenThere: devel@openvz.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: OpenVZ development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: devel-bounces@openvz.org Errors-To: devel-bounces@openvz.org When a disk is attached read-only, QEMU opens the backing block device O_RDONLY and advertises VIRTIO_BLK_F_RO. vhost_blk_set_backend() checks only that the fd is a block device, and requests are submitted as bios straight to the bdev, so a guest that ignores VIRTIO_BLK_F_RO and sends VIRTIO_BLK_T_OUT gets VIRTIO_BLK_S_OK and modifies the disk. Complete VIRTIO_BLK_T_OUT with VIRTIO_BLK_S_IOERR when the backend file lacks FMODE_WRITE or the bdev itself is read-only, as the userspace virtio-blk device does. The bdev is checked per request since it can be switched read-only at runtime. Flush stays allowed: it does not modify data. Fixes: d8722ff88c5d ("drivers/vhost: vhost-blk accelerator for virtio-blk guests") https://virtuozzo.atlassian.net/browse/VSTOR-152127 Feature: vhost-blk: in-kernel accelerator for virtio-blk guests Signed-off-by: Alexander Ivanov --- drivers/vhost/blk.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/drivers/vhost/blk.c b/drivers/vhost/blk.c index b170439a1806..11ded3214c45 100644 --- a/drivers/vhost/blk.c +++ b/drivers/vhost/blk.c @@ -443,6 +443,12 @@ static int vhost_blk_req_submit(struct vhost_blk_req *req) return ret; } +static bool vhost_blk_backend_ro(struct file *f) +{ + return !(f->f_mode & FMODE_WRITE) || + bdev_read_only(I_BDEV(f->f_mapping->host)); +} + static int vhost_blk_req_handle(struct vhost_virtqueue *vq, struct virtio_blk_outhdr *hdr, u16 head, u16 out, u16 in) @@ -480,6 +486,15 @@ static int vhost_blk_req_handle(struct vhost_virtqueue *vq, switch (hdr->type) { case VIRTIO_BLK_T_OUT: + if (vhost_blk_backend_ro(vhost_vq_get_backend(vq))) { + status = VIRTIO_BLK_S_IOERR; + ret = vhost_blk_set_status(req, status); + if (ret) + break; + vhost_add_used_and_signal(&blk->dev, vq, head, + sizeof(status)); + break; + } req->bi_opf = REQ_OP_WRITE; ret = vhost_blk_req_submit(req); break; -- 2.53.0 _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel