Re: [dpdk-stable] [dpdk-dev] [PATCH] vhost: add header check in dequeue offload

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

> 
> When parsing the virtio net header and packet header for dequeue offload,
> we need to perform sanity check on the packet header to ensure:
>   - No out-of-boundary memory access.
>   - The packet header and virtio_net header are valid and aligned.
> 
> Fixes: d0cf91303d73 ("vhost: add Tx offload capabilities")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Xiao Wang <xiao.w.wang@intel.com>
> ---
>  lib/librte_vhost/virtio_net.c | 49 +++++++++++++++++++++++++++++++++++++------
>  1 file changed, 43 insertions(+), 6 deletions(-)
> 
> diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
> index 583bf379c6..0fba0053a3 100644
> --- a/lib/librte_vhost/virtio_net.c
> +++ b/lib/librte_vhost/virtio_net.c
> @@ -1821,44 +1821,64 @@ virtio_net_with_host_offload(struct virtio_net *dev)
>  	return false;
>  }
> 
> -static void
> -parse_ethernet(struct rte_mbuf *m, uint16_t *l4_proto, void **l4_hdr)
> +static int
> +parse_ethernet(struct rte_mbuf *m, uint16_t *l4_proto, void **l4_hdr,
> +		uint16_t *len)
>  {
>  	struct rte_ipv4_hdr *ipv4_hdr;
>  	struct rte_ipv6_hdr *ipv6_hdr;
>  	void *l3_hdr = NULL;
>  	struct rte_ether_hdr *eth_hdr;
>  	uint16_t ethertype;
> +	uint16_t data_len = m->data_len;
> 
>  	eth_hdr = rte_pktmbuf_mtod(m, struct rte_ether_hdr *);
> 
> +	if (data_len <= sizeof(struct rte_ether_hdr))
> +		return -EINVAL;
> +
>  	m->l2_len = sizeof(struct rte_ether_hdr);
>  	ethertype = rte_be_to_cpu_16(eth_hdr->ether_type);
> +	data_len -= sizeof(struct rte_ether_hdr);
> 
>  	if (ethertype == RTE_ETHER_TYPE_VLAN) {
> +		if (data_len <= sizeof(struct rte_vlan_hdr))
> +			return -EINVAL;
> +
>  		struct rte_vlan_hdr *vlan_hdr =
>  			(struct rte_vlan_hdr *)(eth_hdr + 1);
> 
>  		m->l2_len += sizeof(struct rte_vlan_hdr);
>  		ethertype = rte_be_to_cpu_16(vlan_hdr->eth_proto);
> +		data_len -= sizeof(struct rte_vlan_hdr);
>  	}
> 
>  	l3_hdr = (char *)eth_hdr + m->l2_len;
> 
>  	switch (ethertype) {
>  	case RTE_ETHER_TYPE_IPV4:
> +		if (data_len <= sizeof(struct rte_ipv4_hdr))
> +			return -EINVAL;
>  		ipv4_hdr = l3_hdr;
>  		*l4_proto = ipv4_hdr->next_proto_id;
>  		m->l3_len = rte_ipv4_hdr_len(ipv4_hdr);
> +		if (data_len <= m->l3_len) {
> +			m->l3_len = 0;
> +			return -EINVAL;
> +		}
>  		*l4_hdr = (char *)l3_hdr + m->l3_len;
>  		m->ol_flags |= PKT_TX_IPV4;
> +		data_len -= m->l3_len;
>  		break;
>  	case RTE_ETHER_TYPE_IPV6:
> +		if (data_len <= sizeof(struct rte_ipv6_hdr))
> +			return -EINVAL;
>  		ipv6_hdr = l3_hdr;
>  		*l4_proto = ipv6_hdr->proto;
>  		m->l3_len = sizeof(struct rte_ipv6_hdr);
>  		*l4_hdr = (char *)l3_hdr + m->l3_len;
>  		m->ol_flags |= PKT_TX_IPV6;
> +		data_len -= m->l3_len;
>  		break;
>  	default:
>  		m->l3_len = 0;
> @@ -1866,6 +1886,9 @@ parse_ethernet(struct rte_mbuf *m, uint16_t *l4_proto, void **l4_hdr)
>  		*l4_hdr = NULL;
>  		break;
>  	}
> +
> +	*len = data_len;
> +	return 0;
>  }
> 
>  static __rte_always_inline void
> @@ -1874,24 +1897,30 @@ vhost_dequeue_offload(struct virtio_net_hdr *hdr, struct rte_mbuf *m)
>  	uint16_t l4_proto = 0;
>  	void *l4_hdr = NULL;
>  	struct rte_tcp_hdr *tcp_hdr = NULL;
> +	uint16_t len = 0;
> 
>  	if (hdr->flags == 0 && hdr->gso_type == VIRTIO_NET_HDR_GSO_NONE)
>  		return;
> 
> -	parse_ethernet(m, &l4_proto, &l4_hdr);
> +	if (parse_ethernet(m, &l4_proto, &l4_hdr, &len) < 0)
> +		return;
> +
>  	if (hdr->flags == VIRTIO_NET_HDR_F_NEEDS_CSUM) {
>  		if (hdr->csum_start == (m->l2_len + m->l3_len)) {
>  			switch (hdr->csum_offset) {
>  			case (offsetof(struct rte_tcp_hdr, cksum)):
> -				if (l4_proto == IPPROTO_TCP)
> +				if (l4_proto == IPPROTO_TCP &&
> +					len > sizeof(struct rte_tcp_hdr))

Shouldn't it be '>=' here?

>  					m->ol_flags |= PKT_TX_TCP_CKSUM;
>  				break;
>  			case (offsetof(struct rte_udp_hdr, dgram_cksum)):
> -				if (l4_proto == IPPROTO_UDP)
> +				if (l4_proto == IPPROTO_UDP &&
> +					len > sizeof(struct rte_udp_hdr))
>  					m->ol_flags |= PKT_TX_UDP_CKSUM;
>  				break;
>  			case (offsetof(struct rte_sctp_hdr, cksum)):
> -				if (l4_proto == IPPROTO_SCTP)
> +				if (l4_proto == IPPROTO_SCTP &&
> +					len > sizeof(struct rte_sctp_hdr))
>  					m->ol_flags |= PKT_TX_SCTP_CKSUM;
>  				break;
>  			default:
> @@ -1904,12 +1933,20 @@ vhost_dequeue_offload(struct virtio_net_hdr *hdr, struct rte_mbuf *m)
>  		switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
>  		case VIRTIO_NET_HDR_GSO_TCPV4:
>  		case VIRTIO_NET_HDR_GSO_TCPV6:
> +			if (l4_proto != IPPROTO_TCP ||
> +					len <= sizeof(struct rte_tcp_hdr))
> +				break;
>  			tcp_hdr = l4_hdr;
> +			if (len <= (tcp_hdr->data_off & 0xf0) >> 2)
> +				break;
>  			m->ol_flags |= PKT_TX_TCP_SEG;
>  			m->tso_segsz = hdr->gso_size;
>  			m->l4_len = (tcp_hdr->data_off & 0xf0) >> 2;
>  			break;
>  		case VIRTIO_NET_HDR_GSO_UDP:
> +			if (l4_proto != IPPROTO_UDP ||
> +					len <= sizeof(struct rte_udp_hdr))
> +				break;
>  			m->ol_flags |= PKT_TX_UDP_SEG;
>  			m->tso_segsz = hdr->gso_size;
>  			m->l4_len = sizeof(struct rte_udp_hdr);
> --
> 2.15.1