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 <linux/init.h> 15 #include <net/protocol.h> 16 #include <net/gre.h> 17 18 static struct sk_buff *gre_gso_segment(struct sk_buff *skb, 19 netdev_features_t features) 20 { 21 int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb); 22 struct sk_buff *segs = ERR_PTR(-EINVAL); 23 u16 mac_offset = skb->mac_header; 24 __be16 protocol = skb->protocol; 25 u16 mac_len = skb->mac_len; 26 int gre_offset, outer_hlen; 27 bool need_csum; 28 29 if (unlikely(skb_shinfo(skb)->gso_type & 30 ~(SKB_GSO_TCPV4 | 31 SKB_GSO_TCPV6 | 32 SKB_GSO_UDP | 33 SKB_GSO_DODGY | 34 SKB_GSO_TCP_ECN | 35 SKB_GSO_GRE | 36 SKB_GSO_GRE_CSUM | 37 SKB_GSO_IPIP | 38 SKB_GSO_SIT))) 39 goto out; 40 41 if (!skb->encapsulation) 42 goto out; 43 44 if (unlikely(tnl_hlen < sizeof(struct gre_base_hdr))) 45 goto out; 46 47 if (unlikely(!pskb_may_pull(skb, tnl_hlen))) 48 goto out; 49 50 /* setup inner skb. */ 51 skb->encapsulation = 0; 52 __skb_pull(skb, tnl_hlen); 53 skb_reset_mac_header(skb); 54 skb_set_network_header(skb, skb_inner_network_offset(skb)); 55 skb->mac_len = skb_inner_network_offset(skb); 56 skb->protocol = skb->inner_protocol; 57 58 need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_GRE_CSUM); 59 skb->encap_hdr_csum = need_csum; 60 61 features &= skb->dev->hw_enc_features; 62 63 /* segment inner packet. */ 64 segs = skb_mac_gso_segment(skb, features); 65 if (IS_ERR_OR_NULL(segs)) { 66 skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset, 67 mac_len); 68 goto out; 69 } 70 71 outer_hlen = skb_tnl_header_len(skb); 72 gre_offset = outer_hlen - tnl_hlen; 73 skb = segs; 74 do { 75 struct gre_base_hdr *greh; 76 __be32 *pcsum; 77 78 skb_reset_inner_headers(skb); 79 skb->encapsulation = 1; 80 81 skb->mac_len = mac_len; 82 skb->protocol = protocol; 83 84 __skb_push(skb, outer_hlen); 85 skb_reset_mac_header(skb); 86 skb_set_network_header(skb, mac_len); 87 skb_set_transport_header(skb, gre_offset); 88 89 if (!need_csum) 90 continue; 91 92 greh = (struct gre_base_hdr *)skb_transport_header(skb); 93 pcsum = (__be32 *)(greh + 1); 94 95 *pcsum = 0; 96 *(__sum16 *)pcsum = gso_make_checksum(skb, 0); 97 } while ((skb = skb->next)); 98 out: 99 return segs; 100 } 101 102 static struct sk_buff **gre_gro_receive(struct sk_buff **head, 103 struct sk_buff *skb) 104 { 105 struct sk_buff **pp = NULL; 106 struct sk_buff *p; 107 const struct gre_base_hdr *greh; 108 unsigned int hlen, grehlen; 109 unsigned int off; 110 int flush = 1; 111 struct packet_offload *ptype; 112 __be16 type; 113 114 off = skb_gro_offset(skb); 115 hlen = off + sizeof(*greh); 116 greh = skb_gro_header_fast(skb, off); 117 if (skb_gro_header_hard(skb, hlen)) { 118 greh = skb_gro_header_slow(skb, hlen, off); 119 if (unlikely(!greh)) 120 goto out; 121 } 122 123 /* Only support version 0 and K (key), C (csum) flags. Note that 124 * although the support for the S (seq#) flag can be added easily 125 * for GRO, this is problematic for GSO hence can not be enabled 126 * here because a GRO pkt may end up in the forwarding path, thus 127 * requiring GSO support to break it up correctly. 128 */ 129 if ((greh->flags & ~(GRE_KEY|GRE_CSUM)) != 0) 130 goto out; 131 132 type = greh->protocol; 133 134 rcu_read_lock(); 135 ptype = gro_find_receive_by_type(type); 136 if (!ptype) 137 goto out_unlock; 138 139 grehlen = GRE_HEADER_SECTION; 140 141 if (greh->flags & GRE_KEY) 142 grehlen += GRE_HEADER_SECTION; 143 144 if (greh->flags & GRE_CSUM) 145 grehlen += GRE_HEADER_SECTION; 146 147 hlen = off + grehlen; 148 if (skb_gro_header_hard(skb, hlen)) { 149 greh = skb_gro_header_slow(skb, hlen, off); 150 if (unlikely(!greh)) 151 goto out_unlock; 152 } 153 154 /* Don't bother verifying checksum if we're going to flush anyway. */ 155 if ((greh->flags & GRE_CSUM) && !NAPI_GRO_CB(skb)->flush) { 156 if (skb_gro_checksum_simple_validate(skb)) 157 goto out_unlock; 158 159 skb_gro_checksum_try_convert(skb, IPPROTO_GRE, 0, 160 null_compute_pseudo); 161 } 162 163 flush = 0; 164 165 for (p = *head; p; p = p->next) { 166 const struct gre_base_hdr *greh2; 167 168 if (!NAPI_GRO_CB(p)->same_flow) 169 continue; 170 171 /* The following checks are needed to ensure only pkts 172 * from the same tunnel are considered for aggregation. 173 * The criteria for "the same tunnel" includes: 174 * 1) same version (we only support version 0 here) 175 * 2) same protocol (we only support ETH_P_IP for now) 176 * 3) same set of flags 177 * 4) same key if the key field is present. 178 */ 179 greh2 = (struct gre_base_hdr *)(p->data + off); 180 181 if (greh2->flags != greh->flags || 182 greh2->protocol != greh->protocol) { 183 NAPI_GRO_CB(p)->same_flow = 0; 184 continue; 185 } 186 if (greh->flags & GRE_KEY) { 187 /* compare keys */ 188 if (*(__be32 *)(greh2+1) != *(__be32 *)(greh+1)) { 189 NAPI_GRO_CB(p)->same_flow = 0; 190 continue; 191 } 192 } 193 } 194 195 skb_gro_pull(skb, grehlen); 196 197 /* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/ 198 skb_gro_postpull_rcsum(skb, greh, grehlen); 199 200 pp = ptype->callbacks.gro_receive(head, skb); 201 202 out_unlock: 203 rcu_read_unlock(); 204 out: 205 NAPI_GRO_CB(skb)->flush |= flush; 206 207 return pp; 208 } 209 210 static int gre_gro_complete(struct sk_buff *skb, int nhoff) 211 { 212 struct gre_base_hdr *greh = (struct gre_base_hdr *)(skb->data + nhoff); 213 struct packet_offload *ptype; 214 unsigned int grehlen = sizeof(*greh); 215 int err = -ENOENT; 216 __be16 type; 217 218 skb->encapsulation = 1; 219 skb_shinfo(skb)->gso_type = SKB_GSO_GRE; 220 221 type = greh->protocol; 222 if (greh->flags & GRE_KEY) 223 grehlen += GRE_HEADER_SECTION; 224 225 if (greh->flags & GRE_CSUM) 226 grehlen += GRE_HEADER_SECTION; 227 228 rcu_read_lock(); 229 ptype = gro_find_complete_by_type(type); 230 if (ptype) 231 err = ptype->callbacks.gro_complete(skb, nhoff + grehlen); 232 233 rcu_read_unlock(); 234 235 skb_set_inner_mac_header(skb, nhoff + grehlen); 236 237 return err; 238 } 239 240 static const struct net_offload gre_offload = { 241 .callbacks = { 242 .gso_segment = gre_gso_segment, 243 .gro_receive = gre_gro_receive, 244 .gro_complete = gre_gro_complete, 245 }, 246 }; 247 248 static int __init gre_offload_init(void) 249 { 250 return inet_add_offload(&gre_offload, IPPROTO_GRE); 251 } 252 device_initcall(gre_offload_init); 253