path: root/include/linux/virtio_net.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_VIRTIO_NET_H
#define _LINUX_VIRTIO_NET_H

#include <linux/if_vlan.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/udp.h>
#include <uapi/linux/tcp.h>
#include <uapi/linux/virtio_net.h>

static inline bool virtio_net_hdr_match_proto(__be16 protocol, __u8 gso_type)
{
	switch (gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
	case VIRTIO_NET_HDR_GSO_TCPV4:
		return protocol == cpu_to_be16(ETH_P_IP);
	case VIRTIO_NET_HDR_GSO_TCPV6:
		return protocol == cpu_to_be16(ETH_P_IPV6);
	case VIRTIO_NET_HDR_GSO_UDP:
	case VIRTIO_NET_HDR_GSO_UDP_L4:
		return protocol == cpu_to_be16(ETH_P_IP) ||
		       protocol == cpu_to_be16(ETH_P_IPV6);
	default:
		return false;
	}
}

static inline int virtio_net_hdr_set_proto(struct sk_buff *skb,
					   const struct virtio_net_hdr *hdr)
{
	if (skb->protocol)
		return 0;

	switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
	case VIRTIO_NET_HDR_GSO_TCPV4:
	case VIRTIO_NET_HDR_GSO_UDP:
	case VIRTIO_NET_HDR_GSO_UDP_L4:
		skb->protocol = cpu_to_be16(ETH_P_IP);
		break;
	case VIRTIO_NET_HDR_GSO_TCPV6:
		skb->protocol = cpu_to_be16(ETH_P_IPV6);
		break;
	default:
		return -EINVAL;
	}

	return 0;
}

static inline int __virtio_net_hdr_to_skb(struct sk_buff *skb,
					  const struct virtio_net_hdr *hdr,
					  bool little_endian, u8 hdr_gso_type)
{
	unsigned int nh_min_len = sizeof(struct iphdr);
	unsigned int gso_type = 0;
	unsigned int thlen = 0;
	unsigned int p_off = 0;
	unsigned int ip_proto;

	if (hdr_gso_type != VIRTIO_NET_HDR_GSO_NONE) {
		switch (hdr_gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
		case VIRTIO_NET_HDR_GSO_TCPV4:
			gso_type = SKB_GSO_TCPV4;
			ip_proto = IPPROTO_TCP;
			thlen = sizeof(struct tcphdr);
			break;
		case VIRTIO_NET_HDR_GSO_TCPV6:
			gso_type = SKB_GSO_TCPV6;
			ip_proto = IPPROTO_TCP;
			thlen = sizeof(struct tcphdr);
			nh_min_len = sizeof(struct ipv6hdr);
			break;
		case VIRTIO_NET_HDR_GSO_UDP:
			gso_type = SKB_GSO_UDP;
			ip_proto = IPPROTO_UDP;
			thlen = sizeof(struct udphdr);
			break;
		case VIRTIO_NET_HDR_GSO_UDP_L4:
			gso_type = SKB_GSO_UDP_L4;
			ip_proto = IPPROTO_UDP;
			thlen = sizeof(struct udphdr);
			break;
		default:
			return -EINVAL;
		}

		if (hdr_gso_type & VIRTIO_NET_HDR_GSO_ECN)
			gso_type |= SKB_GSO_TCP_ECN;

		if (hdr->gso_size == 0)
			return -EINVAL;
	}

	skb_reset_mac_header(skb);

	if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
		u32 start = __virtio16_to_cpu(little_endian, hdr->csum_start);
		u32 off = __virtio16_to_cpu(little_endian, hdr->csum_offset);
		u32 needed = start + max_t(u32, thlen, off + sizeof(__sum16));

		if (!pskb_may_pull(skb, needed))
			return -EINVAL;

		if (!skb_partial_csum_set(skb, start, off))
			return -EINVAL;
		if (skb_transport_offset(skb) < nh_min_len)
			return -EINVAL;

		nh_min_len = skb_transport_offset(skb);
		p_off = nh_min_len + thlen;
		if (!pskb_may_pull(skb, p_off))
			return -EINVAL;
	} else {
		/* gso packets without NEEDS_CSUM do not set transport_offset.
		 * probe and drop if does not match one of the above types.
		 */
		if (gso_type && skb->network_header) {
			struct flow_keys_basic keys;

			if (!skb->protocol) {
				__be16 protocol = dev_parse_header_protocol(skb);

				if (!protocol)
					virtio_net_hdr_set_proto(skb, hdr);
				else if (!virtio_net_hdr_match_proto(protocol,
								 hdr_gso_type))
					return -EINVAL;
				else
					skb->protocol = protocol;
			}
retry:
			if (!skb_flow_dissect_flow_keys_basic(NULL, skb, &keys,
							      NULL, 0, 0, 0,
							      0)) {
				/* UFO does not specify ipv4 or 6: try both */
				if (gso_type & SKB_GSO_UDP &&
				    skb->protocol == htons(ETH_P_IP)) {
					skb->protocol = htons(ETH_P_IPV6);
					goto retry;
				}
				return -EINVAL;
			}

			p_off = keys.control.thoff + thlen;
			if (!pskb_may_pull(skb, p_off) ||
			    keys.basic.ip_proto != ip_proto)
				return -EINVAL;

			skb_set_transport_header(skb, keys.control.thoff);
		} else if (gso_type) {
			p_off = nh_min_len + thlen;
			if (!pskb_may_pull(skb, p_off))
				return -EINVAL;
		}
	}

	if (hdr_gso_type != VIRTIO_NET_HDR_GSO_NONE) {
		u16 gso_size = __virtio16_to_cpu(little_endian, hdr->gso_size);
		unsigned int nh_off = p_off;
		struct skb_shared_info *shinfo = skb_shinfo(skb);

		switch (gso_type & ~SKB_GSO_TCP_ECN) {
		case SKB_GSO_UDP:
			/* UFO may not include transport header in gso_size. */
			nh_off -= thlen;
			break;
		case SKB_GSO_UDP_L4:
			if (!(hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM))
				return -EINVAL;
			if (skb->csum_offset != offsetof(struct udphdr, check))
				return -EINVAL;
			if (skb->len - p_off > gso_size * UDP_MAX_SEGMENTS)
				return -EINVAL;
			if (gso_type != SKB_GSO_UDP_L4)
				return -EINVAL;
			break;
		case SKB_GSO_TCPV4:
		case SKB_GSO_TCPV6:
			if (skb->ip_summed == CHECKSUM_PARTIAL &&
			    skb->csum_offset != offsetof(struct tcphdr, check))
				return -EINVAL;
			break;
		}

		/* Kernel has a special handling for GSO_BY_FRAGS. */
		if (gso_size == GSO_BY_FRAGS)
			return -EINVAL;

		/* Too small packets are not really GSO ones. */
		if (skb->len - nh_off > gso_size) {
			shinfo->gso_size = gso_size;
			shinfo->gso_type = gso_type;

			/* Header must be checked, and gso_segs computed. */
			shinfo->gso_type |= SKB_GSO_DODGY;
			shinfo->gso_segs = 0;
		}
	}

	return 0;
}

static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
					const struct virtio_net_hdr *hdr,
					bool little_endian)
{
	return __virtio_net_hdr_to_skb(skb, hdr, little_endian, hdr->gso_type);
}

static inline int virtio_net_hdr_from_skb(const struct sk_buff *skb,
					  struct virtio_net_hdr *hdr,
					  bool little_endian,
					  bool has_data_valid,
					  int vlan_hlen)
{
	memset(hdr, 0, sizeof(*hdr));   /* no info leak */

	if (skb_is_gso(skb)) {
		struct skb_shared_info *sinfo = skb_shinfo(skb);

		/* This is a hint as to how much should be linear. */
		hdr->hdr_len = __cpu_to_virtio16(little_endian,
						 skb_headlen(skb));
		hdr->gso_size = __cpu_to_virtio16(little_endian,
						  sinfo->gso_size);
		if (sinfo->gso_type & SKB_GSO_TCPV4)
			hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
		else if (sinfo->gso_type & SKB_GSO_TCPV6)
			hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
		else if (sinfo->gso_type & SKB_GSO_UDP_L4)
			hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP_L4;
		else
			return -EINVAL;
		if (sinfo->gso_type & SKB_GSO_TCP_ECN)
			hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
	} else
		hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;

	if (skb->ip_summed == CHECKSUM_PARTIAL) {
		hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
		hdr->csum_start = __cpu_to_virtio16(little_endian,
			skb_checksum_start_offset(skb) + vlan_hlen);
		hdr->csum_offset = __cpu_to_virtio16(little_endian,
				skb->csum_offset);
	} else if (has_data_valid &&
		   skb->ip_summed == CHECKSUM_UNNECESSARY) {
		hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
	} /* else everything is zero */

	return 0;
}

static inline unsigned int virtio_l3min(bool is_ipv6)
{
	return is_ipv6 ? sizeof(struct ipv6hdr) : sizeof(struct iphdr);
}

static inline int
virtio_net_hdr_tnl_to_skb(struct sk_buff *skb,
			  const struct virtio_net_hdr_v1_hash_tunnel *vhdr,
			  bool tnl_hdr_negotiated,
			  bool tnl_csum_negotiated,
			  bool little_endian)
{
	const struct virtio_net_hdr *hdr = (const struct virtio_net_hdr *)vhdr;
	unsigned int inner_nh, outer_th, inner_th;
	unsigned int inner_l3min, outer_l3min;
	u8 gso_inner_type, gso_tunnel_type;
	bool outer_isv6, inner_isv6;
	int ret;

	gso_tunnel_type = hdr->gso_type & VIRTIO_NET_HDR_GSO_UDP_TUNNEL;
	if (!gso_tunnel_type)
		return virtio_net_hdr_to_skb(skb, hdr, little_endian);

	/* Tunnel not supported/negotiated, but the hdr asks for it. */
	if (!tnl_hdr_negotiated)
		return -EINVAL;

	/* Either ipv4 or ipv6. */
	if (gso_tunnel_type == VIRTIO_NET_HDR_GSO_UDP_TUNNEL)
		return -EINVAL;

	/* The UDP tunnel must carry a GSO packet, but no UFO. */
	gso_inner_type = hdr->gso_type & ~(VIRTIO_NET_HDR_GSO_ECN |
					   VIRTIO_NET_HDR_GSO_UDP_TUNNEL);
	if (!gso_inner_type || gso_inner_type == VIRTIO_NET_HDR_GSO_UDP)
		return -EINVAL;

	/* Rely on csum being present. */
	if (!(hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM))
		return -EINVAL;

	/* Validate offsets. */
	outer_isv6 = gso_tunnel_type & VIRTIO_NET_HDR_GSO_UDP_TUNNEL_IPV6;
	inner_isv6 = gso_inner_type == VIRTIO_NET_HDR_GSO_TCPV6;
	inner_l3min = virtio_l3min(inner_isv6);
	outer_l3min = ETH_HLEN + virtio_l3min(outer_isv6);

	inner_th = __virtio16_to_cpu(little_endian, hdr->csum_start);
	inner_nh = le16_to_cpu(vhdr->inner_nh_offset);
	outer_th = le16_to_cpu(vhdr->outer_th_offset);
	if (outer_th < outer_l3min ||
	    inner_nh < outer_th + sizeof(struct udphdr) ||
	    inner_th < inner_nh + inner_l3min)
		return -EINVAL;

	/* Let the basic parsing deal with plain GSO features. */
	ret = __virtio_net_hdr_to_skb(skb, hdr, true,
				      hdr->gso_type & ~gso_tunnel_type);
	if (ret)
		return ret;

	/* In case of USO, the inner protocol is still unknown and
	 * `inner_isv6` is just a guess, additional parsing is needed.
	 * The previous validation ensures that accessing an ipv4 inner
	 * network header is safe.
	 */
	if (gso_inner_type == VIRTIO_NET_HDR_GSO_UDP_L4) {
		struct iphdr *iphdr = (struct iphdr *)(skb->data + inner_nh);

		inner_isv6 = iphdr->version == 6;
		inner_l3min = virtio_l3min(inner_isv6);
		if (inner_th < inner_nh + inner_l3min)
			return -EINVAL;
	}

	skb_set_inner_protocol(skb, inner_isv6 ? htons(ETH_P_IPV6) :
						 htons(ETH_P_IP));
	if (hdr->flags & VIRTIO_NET_HDR_F_UDP_TUNNEL_CSUM) {
		if (!tnl_csum_negotiated)
			return -EINVAL;

		skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
	} else {
		skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL;
	}

	skb->inner_transport_header = inner_th + skb_headroom(skb);
	skb->inner_network_header = inner_nh + skb_headroom(skb);
	skb->inner_mac_header = inner_nh + skb_headroom(skb);
	skb->transport_header = outer_th + skb_headroom(skb);
	skb->encapsulation = 1;
	return 0;
}

/* Checksum-related fields validation for the driver */
static inline int virtio_net_handle_csum_offload(struct sk_buff *skb,
						 struct virtio_net_hdr *hdr,
						 bool tnl_csum_negotiated)
{
	if (!(hdr->gso_type & VIRTIO_NET_HDR_GSO_UDP_TUNNEL)) {
		if (!(hdr->flags & VIRTIO_NET_HDR_F_DATA_VALID))
			return 0;

		skb->ip_summed = CHECKSUM_UNNECESSARY;
		if (!(hdr->flags & VIRTIO_NET_HDR_F_UDP_TUNNEL_CSUM))
			return 0;

		/* tunnel csum packets are invalid when the related
		 * feature has not been negotiated
		 */
		if (!tnl_csum_negotiated)
			return -EINVAL;
		skb->csum_level = 1;
		return 0;
	}

	/* DATA_VALID is mutually exclusive with NEEDS_CSUM, and GSO
	 * over UDP tunnel requires the latter
	 */
	if (hdr->flags & VIRTIO_NET_HDR_F_DATA_VALID)
		return -EINVAL;
	return 0;
}

/*
 * vlan_hlen always refers to the outermost MAC header. That also
 * means it refers to the only MAC header, if the packet does not carry
 * any encapsulation.
 */
static inline int
virtio_net_hdr_tnl_from_skb(const struct sk_buff *skb,
			    struct virtio_net_hdr_v1_hash_tunnel *vhdr,
			    bool tnl_hdr_negotiated,
			    bool little_endian,
			    int vlan_hlen)
{
	struct virtio_net_hdr *hdr = (struct virtio_net_hdr *)vhdr;
	unsigned int inner_nh, outer_th;
	int tnl_gso_type;
	int ret;

	tnl_gso_type = skb_shinfo(skb)->gso_type & (SKB_GSO_UDP_TUNNEL |
						    SKB_GSO_UDP_TUNNEL_CSUM);
	if (!tnl_gso_type)
		return virtio_net_hdr_from_skb(skb, hdr, little_endian, false,
					       vlan_hlen);

	/* Tunnel support not negotiated but skb ask for it. */
	if (!tnl_hdr_negotiated)
		return -EINVAL;

	/* Let the basic parsing deal with plain GSO features. */
	skb_shinfo(skb)->gso_type &= ~tnl_gso_type;
	ret = virtio_net_hdr_from_skb(skb, hdr, true, false, vlan_hlen);
	skb_shinfo(skb)->gso_type |= tnl_gso_type;
	if (ret)
		return ret;

	if (skb->protocol == htons(ETH_P_IPV6))
		hdr->gso_type |= VIRTIO_NET_HDR_GSO_UDP_TUNNEL_IPV6;
	else
		hdr->gso_type |= VIRTIO_NET_HDR_GSO_UDP_TUNNEL_IPV4;

	if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL_CSUM)
		hdr->flags |= VIRTIO_NET_HDR_F_UDP_TUNNEL_CSUM;

	inner_nh = skb->inner_network_header - skb_headroom(skb);
	outer_th = skb->transport_header - skb_headroom(skb);
	vhdr->inner_nh_offset = cpu_to_le16(inner_nh);
	vhdr->outer_th_offset = cpu_to_le16(outer_th);
	return 0;
}

#endif /* _LINUX_VIRTIO_NET_H */