// SPDX-License-Identifier: GPL-2.0-or-later /* * IPV4 GSO/GRO offload support * Linux INET implementation * * GRE GSO support */ #include <linux/skbuff.h> #include <linux/init.h> #include <net/protocol.h> #include <net/gre.h> #include <net/gro.h> #include <net/gso.h> static struct sk_buff *gre_gso_segment(struct sk_buff *skb, netdev_features_t features) { int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb); bool need_csum, offload_csum, gso_partial, need_ipsec; struct sk_buff *segs = ERR_PTR(-EINVAL); u16 mac_offset = skb->mac_header; __be16 protocol = skb->protocol; u16 mac_len = skb->mac_len; int gre_offset, outer_hlen; if (!skb->encapsulation) goto out; if (unlikely(tnl_hlen < sizeof(struct gre_base_hdr))) goto out; if (unlikely(!pskb_may_pull(skb, tnl_hlen))) goto out; /* setup inner skb. */ skb->encapsulation = 0; SKB_GSO_CB(skb)->encap_level = 0; __skb_pull(skb, tnl_hlen); skb_reset_mac_header(skb); skb_set_network_header(skb, skb_inner_network_offset(skb)); skb->mac_len = skb_inner_network_offset(skb); skb->protocol = skb->inner_protocol; need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_GRE_CSUM); skb->encap_hdr_csum = need_csum; features &= skb->dev->hw_enc_features; if (need_csum) features &= ~NETIF_F_SCTP_CRC; need_ipsec = skb_dst(skb) && dst_xfrm(skb_dst(skb)); /* Try to offload checksum if possible */ offload_csum = !!(need_csum && !need_ipsec && (skb->dev->features & NETIF_F_HW_CSUM)); /* segment inner packet. */ segs = skb_mac_gso_segment(skb, features); if (IS_ERR_OR_NULL(segs)) { skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset, mac_len); goto out; } gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL); outer_hlen = skb_tnl_header_len(skb); gre_offset = outer_hlen - tnl_hlen; skb = segs; do { struct gre_base_hdr *greh; __sum16 *pcsum; /* Set up inner headers if we are offloading inner checksum */ if (skb->ip_summed == CHECKSUM_PARTIAL) { skb_reset_inner_headers(skb); skb->encapsulation = 1; } skb->mac_len = mac_len; skb->protocol = protocol; __skb_push(skb, outer_hlen); skb_reset_mac_header(skb); skb_set_network_header(skb, mac_len); skb_set_transport_header(skb, gre_offset); if (!need_csum) continue; greh = (struct gre_base_hdr *)skb_transport_header(skb); pcsum = (__sum16 *)(greh + 1); if (gso_partial && skb_is_gso(skb)) { unsigned int partial_adj; /* Adjust checksum to account for the fact that * the partial checksum is based on actual size * whereas headers should be based on MSS size. */ partial_adj = skb->len + skb_headroom(skb) - SKB_GSO_CB(skb)->data_offset - skb_shinfo(skb)->gso_size; *pcsum = ~csum_fold((__force __wsum)htonl(partial_adj)); } else { *pcsum = 0; } *(pcsum + 1) = 0; if (skb->encapsulation || !offload_csum) { *pcsum = gso_make_checksum(skb, 0); } else { skb->ip_summed = CHECKSUM_PARTIAL; skb->csum_start = skb_transport_header(skb) - skb->head; skb->csum_offset = sizeof(*greh); } } while ((skb = skb->next)); out: return segs; } static struct sk_buff *gre_gro_receive(struct list_head *head, struct sk_buff *skb) { struct sk_buff *pp = NULL; struct sk_buff *p; const struct gre_base_hdr *greh; unsigned int hlen, grehlen; unsigned int off; int flush = 1; struct packet_offload *ptype; __be16 type; if (NAPI_GRO_CB(skb)->encap_mark) goto out; NAPI_GRO_CB(skb)->encap_mark = 1; off = skb_gro_offset(skb); hlen = off + sizeof(*greh); greh = skb_gro_header(skb, hlen, off); if (unlikely(!greh)) goto out; /* Only support version 0 and K (key), C (csum) flags. Note that * although the support for the S (seq#) flag can be added easily * for GRO, this is problematic for GSO hence can not be enabled * here because a GRO pkt may end up in the forwarding path, thus * requiring GSO support to break it up correctly. */ if ((greh->flags & ~(GRE_KEY|GRE_CSUM)) != 0) goto out; /* We can only support GRE_CSUM if we can track the location of * the GRE header. In the case of FOU/GUE we cannot because the * outer UDP header displaces the GRE header leaving us in a state * of limbo. */ if ((greh->flags & GRE_CSUM) && NAPI_GRO_CB(skb)->is_fou) goto out; type = greh->protocol; ptype = gro_find_receive_by_type(type); if (!ptype) goto out; grehlen = GRE_HEADER_SECTION; if (greh->flags & GRE_KEY) grehlen += GRE_HEADER_SECTION; if (greh->flags & GRE_CSUM) grehlen += GRE_HEADER_SECTION; hlen = off + grehlen; if (!skb_gro_may_pull(skb, hlen)) { greh = skb_gro_header_slow(skb, hlen, off); if (unlikely(!greh)) goto out; } /* Don't bother verifying checksum if we're going to flush anyway. */ if ((greh->flags & GRE_CSUM) && !NAPI_GRO_CB(skb)->flush) { if (skb_gro_checksum_simple_validate(skb)) goto out; skb_gro_checksum_try_convert(skb, IPPROTO_GRE, null_compute_pseudo); } list_for_each_entry(p, head, list) { const struct gre_base_hdr *greh2; if (!NAPI_GRO_CB(p)->same_flow) continue; /* The following checks are needed to ensure only pkts * from the same tunnel are considered for aggregation. * The criteria for "the same tunnel" includes: * 1) same version (we only support version 0 here) * 2) same protocol (we only support ETH_P_IP for now) * 3) same set of flags * 4) same key if the key field is present. */ greh2 = (struct gre_base_hdr *)(p->data + off); if (greh2->flags != greh->flags || greh2->protocol != greh->protocol) { NAPI_GRO_CB(p)->same_flow = 0; continue; } if (greh->flags & GRE_KEY) { /* compare keys */ if (*(__be32 *)(greh2+1) != *(__be32 *)(greh+1)) { NAPI_GRO_CB(p)->same_flow = 0; continue; } } } skb_gro_pull(skb, grehlen); /* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/ skb_gro_postpull_rcsum(skb, greh, grehlen); pp = call_gro_receive(ptype->callbacks.gro_receive, head, skb); flush = 0; out: skb_gro_flush_final(skb, pp, flush); return pp; } static int gre_gro_complete(struct sk_buff *skb, int nhoff) { struct gre_base_hdr *greh = (struct gre_base_hdr *)(skb->data + nhoff); struct packet_offload *ptype; unsigned int grehlen = sizeof(*greh); int err = -ENOENT; __be16 type; skb->encapsulation = 1; skb_shinfo(skb)->gso_type = SKB_GSO_GRE; type = greh->protocol; if (greh->flags & GRE_KEY) grehlen += GRE_HEADER_SECTION; if (greh->flags & GRE_CSUM) grehlen += GRE_HEADER_SECTION; ptype = gro_find_complete_by_type(type); if (ptype) err = ptype->callbacks.gro_complete(skb, nhoff + grehlen); skb_set_inner_mac_header(skb, nhoff + grehlen); return err; } static const struct net_offload gre_offload = { .callbacks = { .gso_segment = gre_gso_segment, .gro_receive = gre_gro_receive, .gro_complete = gre_gro_complete, }, }; static int __init gre_offload_init(void) { int err; err = inet_add_offload(&gre_offload, IPPROTO_GRE); #if IS_ENABLED(CONFIG_IPV6) if (err) return err; err = inet6_add_offload(&gre_offload, IPPROTO_GRE); if (err) inet_del_offload(&gre_offload, IPPROTO_GRE); #endif return err; } device_initcall(gre_offload_init);