1 /* 2 * IPV4 GSO/GRO offload support 3 * Linux INET implementation 4 * 5 * This program is free software; you can redistribute it and/or 6 * modify it under the terms of the GNU General Public License 7 * as published by the Free Software Foundation; either version 8 * 2 of the License, or (at your option) any later version. 9 * 10 * GRE GSO support 11 */ 12 13 #include <linux/skbuff.h> 14 #include <net/protocol.h> 15 #include <net/gre.h> 16 17 static int gre_gso_send_check(struct sk_buff *skb) 18 { 19 if (!skb->encapsulation) 20 return -EINVAL; 21 return 0; 22 } 23 24 static struct sk_buff *gre_gso_segment(struct sk_buff *skb, 25 netdev_features_t features) 26 { 27 struct sk_buff *segs = ERR_PTR(-EINVAL); 28 netdev_features_t enc_features; 29 int ghl = GRE_HEADER_SECTION; 30 struct gre_base_hdr *greh; 31 int mac_len = skb->mac_len; 32 __be16 protocol = skb->protocol; 33 int tnl_hlen; 34 bool csum; 35 36 if (unlikely(skb_shinfo(skb)->gso_type & 37 ~(SKB_GSO_TCPV4 | 38 SKB_GSO_TCPV6 | 39 SKB_GSO_UDP | 40 SKB_GSO_DODGY | 41 SKB_GSO_TCP_ECN | 42 SKB_GSO_GRE | 43 SKB_GSO_IPIP))) 44 goto out; 45 46 if (unlikely(!pskb_may_pull(skb, sizeof(*greh)))) 47 goto out; 48 49 greh = (struct gre_base_hdr *)skb_transport_header(skb); 50 51 if (greh->flags & GRE_KEY) 52 ghl += GRE_HEADER_SECTION; 53 if (greh->flags & GRE_SEQ) 54 ghl += GRE_HEADER_SECTION; 55 if (greh->flags & GRE_CSUM) { 56 ghl += GRE_HEADER_SECTION; 57 csum = true; 58 } else 59 csum = false; 60 61 /* setup inner skb. */ 62 skb->protocol = greh->protocol; 63 skb->encapsulation = 0; 64 65 if (unlikely(!pskb_may_pull(skb, ghl))) 66 goto out; 67 68 __skb_pull(skb, ghl); 69 skb_reset_mac_header(skb); 70 skb_set_network_header(skb, skb_inner_network_offset(skb)); 71 skb->mac_len = skb_inner_network_offset(skb); 72 73 /* segment inner packet. */ 74 enc_features = skb->dev->hw_enc_features & netif_skb_features(skb); 75 segs = skb_mac_gso_segment(skb, enc_features); 76 if (!segs || IS_ERR(segs)) 77 goto out; 78 79 skb = segs; 80 tnl_hlen = skb_tnl_header_len(skb); 81 do { 82 __skb_push(skb, ghl); 83 if (csum) { 84 __be32 *pcsum; 85 86 if (skb_has_shared_frag(skb)) { 87 int err; 88 89 err = __skb_linearize(skb); 90 if (err) { 91 kfree_skb_list(segs); 92 segs = ERR_PTR(err); 93 goto out; 94 } 95 } 96 97 greh = (struct gre_base_hdr *)(skb->data); 98 pcsum = (__be32 *)(greh + 1); 99 *pcsum = 0; 100 *(__sum16 *)pcsum = csum_fold(skb_checksum(skb, 0, skb->len, 0)); 101 } 102 __skb_push(skb, tnl_hlen - ghl); 103 104 skb_reset_inner_headers(skb); 105 skb->encapsulation = 1; 106 107 skb_reset_mac_header(skb); 108 skb_set_network_header(skb, mac_len); 109 skb->mac_len = mac_len; 110 skb->protocol = protocol; 111 } while ((skb = skb->next)); 112 out: 113 return segs; 114 } 115 116 static const struct net_offload gre_offload = { 117 .callbacks = { 118 .gso_send_check = gre_gso_send_check, 119 .gso_segment = gre_gso_segment, 120 }, 121 }; 122 123 int __init gre_offload_init(void) 124 { 125 return inet_add_offload(&gre_offload, IPPROTO_GRE); 126 } 127 128 void __exit gre_offload_exit(void) 129 { 130 inet_del_offload(&gre_offload, IPPROTO_GRE); 131 } 132