/* 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);
}

/* This function must be called after virtio_net_hdr_from_skb(). */
static inline void __virtio_net_set_hdrlen(const struct sk_buff *skb,
                                           struct virtio_net_hdr *hdr,
                                           bool little_endian)
{
        u16 hdr_len;

        hdr_len = skb_transport_offset(skb);

        if (hdr->gso_type == VIRTIO_NET_HDR_GSO_UDP_L4)
                hdr_len += sizeof(struct udphdr);
        else
                hdr_len += tcp_hdrlen(skb);

        hdr->hdr_len = __cpu_to_virtio16(little_endian, hdr_len);
}

/* This function must be called after virtio_net_hdr_from_skb(). */
static inline void __virtio_net_set_tnl_hdrlen(const struct sk_buff *skb,
                                               struct virtio_net_hdr *hdr)
{
        u16 hdr_len;

        hdr_len = skb_inner_transport_offset(skb);

        if (hdr->gso_type == VIRTIO_NET_HDR_GSO_UDP_L4)
                hdr_len += sizeof(struct udphdr);
        else
                hdr_len += inner_tcp_hdrlen(skb);

        hdr->hdr_len = __cpu_to_virtio16(true, hdr_len);
}

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,
                            bool has_data_valid,
                            bool feature_hdrlen)
{
        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) {
                ret = virtio_net_hdr_from_skb(skb, hdr, little_endian,
                                              has_data_valid, vlan_hlen);
                if (ret)
                        return ret;

                if (feature_hdrlen && hdr->hdr_len)
                        __virtio_net_set_hdrlen(skb, hdr, little_endian);

                return ret;
        }

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

        vhdr->hash_hdr.hash_value_lo = 0;
        vhdr->hash_hdr.hash_value_hi = 0;
        vhdr->hash_hdr.hash_report = 0;
        vhdr->hash_hdr.padding = 0;

        /* 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 (feature_hdrlen && hdr->hdr_len)
                __virtio_net_set_tnl_hdrlen(skb, hdr);

        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 */