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 goto out; 44 45 if (unlikely(!pskb_may_pull(skb, sizeof(*greh)))) 46 goto out; 47 48 greh = (struct gre_base_hdr *)skb_transport_header(skb); 49 50 if (greh->flags & GRE_KEY) 51 ghl += GRE_HEADER_SECTION; 52 if (greh->flags & GRE_SEQ) 53 ghl += GRE_HEADER_SECTION; 54 if (greh->flags & GRE_CSUM) { 55 ghl += GRE_HEADER_SECTION; 56 csum = true; 57 } else 58 csum = false; 59 60 /* setup inner skb. */ 61 skb->protocol = greh->protocol; 62 skb->encapsulation = 0; 63 64 if (unlikely(!pskb_may_pull(skb, ghl))) 65 goto out; 66 67 __skb_pull(skb, ghl); 68 skb_reset_mac_header(skb); 69 skb_set_network_header(skb, skb_inner_network_offset(skb)); 70 skb->mac_len = skb_inner_network_offset(skb); 71 72 /* segment inner packet. */ 73 enc_features = skb->dev->hw_enc_features & netif_skb_features(skb); 74 segs = skb_mac_gso_segment(skb, enc_features); 75 if (!segs || IS_ERR(segs)) 76 goto out; 77 78 skb = segs; 79 tnl_hlen = skb_tnl_header_len(skb); 80 do { 81 __skb_push(skb, ghl); 82 if (csum) { 83 __be32 *pcsum; 84 85 if (skb_has_shared_frag(skb)) { 86 int err; 87 88 err = __skb_linearize(skb); 89 if (err) { 90 kfree_skb_list(segs); 91 segs = ERR_PTR(err); 92 goto out; 93 } 94 } 95 96 greh = (struct gre_base_hdr *)(skb->data); 97 pcsum = (__be32 *)(greh + 1); 98 *pcsum = 0; 99 *(__sum16 *)pcsum = csum_fold(skb_checksum(skb, 0, skb->len, 0)); 100 } 101 __skb_push(skb, tnl_hlen - ghl); 102 103 skb_reset_inner_headers(skb); 104 skb->encapsulation = 1; 105 106 skb_reset_mac_header(skb); 107 skb_set_network_header(skb, mac_len); 108 skb->mac_len = mac_len; 109 skb->protocol = protocol; 110 } while ((skb = skb->next)); 111 out: 112 return segs; 113 } 114 115 static const struct net_offload gre_offload = { 116 .callbacks = { 117 .gso_send_check = gre_gso_send_check, 118 .gso_segment = gre_gso_segment, 119 }, 120 }; 121 122 int __init gre_offload_init(void) 123 { 124 return inet_add_offload(&gre_offload, IPPROTO_GRE); 125 } 126 127 void __exit gre_offload_exit(void) 128 { 129 inet_del_offload(&gre_offload, IPPROTO_GRE); 130 } 131