From mboxrd@z Thu Jan 1 00:00:00 1970 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0CC9EC433EF for ; Tue, 12 Oct 2021 06:53:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EB2EE608FE for ; Tue, 12 Oct 2021 06:53:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233928AbhJLGzh (ORCPT ); Tue, 12 Oct 2021 02:55:37 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:53144 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233528AbhJLGz1 (ORCPT ); Tue, 12 Oct 2021 02:55:27 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1634021605; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Zx6V3WkZ6K+btb3x/HtCeDn7JI6wkEr2x6cSUYH8Exg=; b=F/1MSTE1iPGfedVAN8pOPZoBcr/zKMRvlmpgO0EHvti855H3aBBiSGWBn2fINMMX5t5Q3a 5gnu8CVSzJCWAf+NDZeIu5nNNsluVe+wtmnEUscMgxdf2aVs6ec5sEykQOJG5xsGf7N62l gHLz6bq1RYCQEVufnxYbRzr445UoUXQ= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-515-VZVAogCfMpSavLjgBlgxFA-1; Tue, 12 Oct 2021 02:53:22 -0400 X-MC-Unique: VZVAogCfMpSavLjgBlgxFA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 9A2BD80417F; Tue, 12 Oct 2021 06:53:04 +0000 (UTC) Received: from localhost.localdomain (ovpn-13-111.pek2.redhat.com [10.72.13.111]) by smtp.corp.redhat.com (Postfix) with ESMTP id EF5195F4E0; Tue, 12 Oct 2021 06:53:01 +0000 (UTC) From: Jason Wang To: mst@redhat.com, jasowang@redhat.com Cc: virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, f.hetzelt@tu-berlin.de, david.kaplan@amd.com, konrad.wilk@oracle.com Subject: [PATCH V2 09/12] virtio_ring: validate used buffer length Date: Tue, 12 Oct 2021 14:52:24 +0800 Message-Id: <20211012065227.9953-10-jasowang@redhat.com> In-Reply-To: <20211012065227.9953-1-jasowang@redhat.com> References: <20211012065227.9953-1-jasowang@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch validate the used buffer length provided by the device before trying to use it. This is done by record the in buffer length in a new field in desc_state structure during virtqueue_add(), then we can fail the virtqueue_get_buf() when we find the device is trying to give us a used buffer length which is greater than the in buffer length. Since some drivers have already done the validation by itself, this patch tries to makes the core validation optional. For the driver that doesn't want the validation, it can set the validate_used to be true (which could be overridden by force_used_validation). To be more efficient, a dedicate array is used for storing the validate used length, this helps to eliminate the cache stress if validation is done by the driver. Signed-off-by: Jason Wang --- drivers/virtio/virtio_ring.c | 56 ++++++++++++++++++++++++++++++++++++ include/linux/virtio.h | 2 ++ 2 files changed, 58 insertions(+) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index d2ca0a7365f8..dee962bd8b04 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -14,6 +14,9 @@ #include #include +static bool force_used_validation = false; +module_param(force_used_validation, bool, 0444); + #ifdef DEBUG /* For development, we want to crash whenever the ring is screwed. */ #define BAD_RING(_vq, fmt, args...) \ @@ -182,6 +185,9 @@ struct vring_virtqueue { } packed; }; + /* Per-descriptor in buffer length */ + u32 *buflen; + /* How to notify other side. FIXME: commonalize hcalls! */ bool (*notify)(struct virtqueue *vq); @@ -490,6 +496,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq, unsigned int i, n, avail, descs_used, prev, err_idx; int head; bool indirect; + u32 buflen = 0; START_USE(vq); @@ -571,6 +578,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq, VRING_DESC_F_NEXT | VRING_DESC_F_WRITE, indirect); + buflen += sg->length; } } /* Last one doesn't continue. */ @@ -610,6 +618,10 @@ static inline int virtqueue_add_split(struct virtqueue *_vq, else vq->split.desc_state[head].indir_desc = ctx; + /* Store in buffer length if necessary */ + if (vq->buflen) + vq->buflen[head] = buflen; + /* Put entry in available array (but don't update avail->idx until they * do sync). */ avail = vq->split.avail_idx_shadow & (vq->split.vring.num - 1); @@ -784,6 +796,11 @@ static void *virtqueue_get_buf_ctx_split(struct virtqueue *_vq, BAD_RING(vq, "id %u is not a head!\n", i); return NULL; } + if (vq->buflen && unlikely(*len > vq->buflen[i])) { + BAD_RING(vq, "used len %d is larger than in buflen %u\n", + *len, vq->buflen[i]); + return NULL; + } /* detach_buf_split clears data, so grab it now. */ ret = vq->split.desc_state[i].data; @@ -1062,6 +1079,7 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq, unsigned int i, n, err_idx; u16 head, id; dma_addr_t addr; + u32 buflen = 0; head = vq->packed.next_avail_idx; desc = alloc_indirect_packed(total_sg, gfp); @@ -1089,6 +1107,8 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq, desc[i].addr = cpu_to_le64(addr); desc[i].len = cpu_to_le32(sg->length); i++; + if (n >= out_sgs) + buflen += sg->length; } } @@ -1142,6 +1162,10 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq, vq->packed.desc_state[id].indir_desc = desc; vq->packed.desc_state[id].last = id; + /* Store in buffer length if necessary */ + if (vq->buflen) + vq->buflen[id] = buflen; + vq->num_added += 1; pr_debug("Added buffer head %i to %p\n", head, vq); @@ -1176,6 +1200,7 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq, unsigned int i, n, c, descs_used, err_idx; __le16 head_flags, flags; u16 head, id, prev, curr, avail_used_flags; + u32 buflen = 0; START_USE(vq); @@ -1250,6 +1275,8 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq, 1 << VRING_PACKED_DESC_F_AVAIL | 1 << VRING_PACKED_DESC_F_USED; } + if (n >= out_sgs) + buflen += sg->length; } } @@ -1269,6 +1296,10 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq, vq->packed.desc_state[id].indir_desc = ctx; vq->packed.desc_state[id].last = prev; + /* Store in buffer length if necessary */ + if (vq->buflen) + vq->buflen[id] = buflen; + /* * A driver MUST NOT make the first descriptor in the list * available before all subsequent descriptors comprising @@ -1455,6 +1486,11 @@ static void *virtqueue_get_buf_ctx_packed(struct virtqueue *_vq, BAD_RING(vq, "id %u is not a head!\n", id); return NULL; } + if (vq->buflen && unlikely(*len > vq->buflen[id])) { + BAD_RING(vq, "used len %d is larger than in buflen %u\n", + *len, vq->buflen[id]); + return NULL; + } /* detach_buf_packed clears data, so grab it now. */ ret = vq->packed.desc_state[id].data; @@ -1660,6 +1696,7 @@ static struct virtqueue *vring_create_virtqueue_packed( struct vring_virtqueue *vq; struct vring_packed_desc *ring; struct vring_packed_desc_event *driver, *device; + struct virtio_driver *drv = drv_to_virtio(vdev->dev.driver); dma_addr_t ring_dma_addr, driver_event_dma_addr, device_event_dma_addr; size_t ring_size_in_bytes, event_size_in_bytes; @@ -1749,6 +1786,13 @@ static struct virtqueue *vring_create_virtqueue_packed( if (!vq->packed.desc_extra) goto err_desc_extra; + if (!drv->validate_used || force_used_validation) { + vq->buflen = kmalloc_array(num, sizeof(*vq->buflen), + GFP_KERNEL); + if (!vq->buflen) + goto err_buflen; + } + /* No callback? Tell other side not to bother us. */ if (!callback) { vq->packed.event_flags_shadow = VRING_PACKED_EVENT_FLAG_DISABLE; @@ -1761,6 +1805,8 @@ static struct virtqueue *vring_create_virtqueue_packed( spin_unlock(&vdev->vqs_list_lock); return &vq->vq; +err_buflen: + kfree(vq->packed.desc_extra); err_desc_extra: kfree(vq->packed.desc_state); err_desc_state: @@ -2168,6 +2214,7 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index, void (*callback)(struct virtqueue *), const char *name) { + struct virtio_driver *drv = drv_to_virtio(vdev->dev.driver); struct vring_virtqueue *vq; if (virtio_has_feature(vdev, VIRTIO_F_RING_PACKED)) @@ -2227,6 +2274,13 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index, if (!vq->split.desc_extra) goto err_extra; + if (!drv->validate_used || force_used_validation) { + vq->buflen = kmalloc_array(vring.num, sizeof(*vq->buflen), + GFP_KERNEL); + if (!vq->buflen) + goto err_buflen; + } + /* Put everything in free lists. */ vq->free_head = 0; memset(vq->split.desc_state, 0, vring.num * @@ -2237,6 +2291,8 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index, spin_unlock(&vdev->vqs_list_lock); return &vq->vq; +err_buflen: + kfree(vq->split.desc_extra); err_extra: kfree(vq->split.desc_state); err_state: diff --git a/include/linux/virtio.h b/include/linux/virtio.h index 0cd8685aeba4..79e4f6765e3a 100644 --- a/include/linux/virtio.h +++ b/include/linux/virtio.h @@ -153,6 +153,7 @@ size_t virtio_max_dma_size(struct virtio_device *vdev); * @feature_table_legacy: same as feature_table but when working in legacy mode. * @feature_table_size_legacy: number of entries in feature table legacy array. * @validate: optional function to do early checks + * @validate_used: whether the driver can validate used buffer length * @probe: the function to call when a device is found. Returns 0 or -errno. * @scan: optional function to call after successful probe; intended * for virtio-scsi to invoke a scan. @@ -169,6 +170,7 @@ struct virtio_driver { unsigned int feature_table_size; const unsigned int *feature_table_legacy; unsigned int feature_table_size_legacy; + bool validate_used; int (*validate)(struct virtio_device *dev); int (*probe)(struct virtio_device *dev); void (*scan)(struct virtio_device *dev); -- 2.25.1