[dpdk-dev] [PATCH 03/12] vhost: introduce safe API for GPA translation

[Maxime Coquelin]

This new rte_vhost_va_from_guest_pa API takes an extra len
parameter, used to specify the size of the range to be mapped.
Effective mapped range is returned via len parameter.

This issue has been assigned CVE-2018-1059.

Reported-by: Yongji Xie <xieyongji at baidu.com>
Signed-off-by: Maxime Coquelin <maxime.coquelin at redhat.com>
---
 lib/librte_vhost/rte_vhost.h           | 40 ++++++++++++++++++++++++++++++++++
 lib/librte_vhost/rte_vhost_version.map |  4 +++-
 lib/librte_vhost/vhost.h               |  2 +-
 3 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/lib/librte_vhost/rte_vhost.h b/lib/librte_vhost/rte_vhost.h
index e4e8824c9..7d065137a 100644
--- a/lib/librte_vhost/rte_vhost.h
+++ b/lib/librte_vhost/rte_vhost.h
@@ -149,6 +149,46 @@ rte_vhost_gpa_to_vva(struct rte_vhost_memory *mem, uint64_t gpa)
 	return 0;
 }
 
+/**
+ * Convert guest physical address to host virtual address safely
+ *
+ * This variant of rte_vhost_gpa_to_vva() takes care all the
+ * requested length is mapped and contiguous in process address
+ * space.
+ *
+ * @param mem
+ *  the guest memory regions
+ * @param gpa
+ *  the guest physical address for querying
+ * @param len
+ *  the size of the requested area to map, updated with actual size mapped
+ * @return
+ *  the host virtual address on success, 0 on failure
+ */
+static __rte_always_inline uint64_t
+rte_vhost_va_from_guest_pa(struct rte_vhost_memory *mem,
+						   uint64_t gpa, uint64_t *len)
+{
+	struct rte_vhost_mem_region *r;
+	uint32_t i;
+
+	for (i = 0; i < mem->nregions; i++) {
+		r = &mem->regions[i];
+		if (gpa >= r->guest_phys_addr &&
+		    gpa <  r->guest_phys_addr + r->size) {
+
+			if (unlikely(*len > r->guest_phys_addr + r->size - gpa))
+				*len = r->guest_phys_addr + r->size - gpa;
+
+			return gpa - r->guest_phys_addr +
+			       r->host_user_addr;
+		}
+	}
+	*len = 0;
+
+	return 0;
+}
+
 #define RTE_VHOST_NEED_LOG(features)	((features) & (1ULL << VHOST_F_LOG_ALL))
 
 /**
diff --git a/lib/librte_vhost/rte_vhost_version.map b/lib/librte_vhost/rte_vhost_version.map
index b9d338077..8243bcabf 100644
--- a/lib/librte_vhost/rte_vhost_version.map
+++ b/lib/librte_vhost/rte_vhost_version.map
@@ -61,6 +61,8 @@ DPDK_18.02 {
 } DPDK_17.08;
 
 EXPERIMENTAL {
+	global:
+
 	rte_vdpa_register_device;
 	rte_vdpa_unregister_device;
 	rte_vdpa_find_device_id;
@@ -79,5 +81,5 @@ EXPERIMENTAL {
 	rte_vhost_crypto_fetch_requests;
 	rte_vhost_crypto_finalize_requests;
 	rte_vhost_crypto_set_zero_copy;
-
+	rte_vhost_va_from_guest_pa;
 } DPDK_18.02;
diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
index f7dbd2c94..ba2fc7404 100644
--- a/lib/librte_vhost/vhost.h
+++ b/lib/librte_vhost/vhost.h
@@ -446,7 +446,7 @@ vhost_iova_to_vva(struct virtio_net *dev, struct vhost_virtqueue *vq,
 			uint64_t iova, uint64_t *len, uint8_t perm)
 {
 	if (!(dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM)))
-		return rte_vhost_gpa_to_vva(dev->mem, iova);
+		return rte_vhost_va_from_guest_pa(dev->mem, iova, len);
 
 	return __vhost_iova_to_vva(dev, vq, iova, len, perm);
 }
-- 
2.14.3