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, ufo; 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_GSO_CB(skb)->encap_level = 0; 53 __skb_pull(skb, tnl_hlen); 54 skb_reset_mac_header(skb); 55 skb_set_network_header(skb, skb_inner_network_offset(skb)); 56 skb->mac_len = skb_inner_network_offset(skb); 57 skb->protocol = skb->inner_protocol; 58 59 need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_GRE_CSUM); 60 skb->encap_hdr_csum = need_csum; 61 62 ufo = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP); 63 64 features &= skb->dev->hw_enc_features; 65 66 /* The only checksum offload we care about from here on out is the 67 * outer one so strip the existing checksum feature flags based 68 * on the fact that we will be computing our checksum in software. 69 */ 70 if (ufo) { 71 features &= ~NETIF_F_CSUM_MASK; 72 if (!need_csum) 73 features |= NETIF_F_HW_CSUM; 74 } 75 76 /* segment inner packet. */ 77 segs = skb_mac_gso_segment(skb, features); 78 if (IS_ERR_OR_NULL(segs)) { 79 skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset, 80 mac_len); 81 goto out; 82 } 83 84 outer_hlen = skb_tnl_header_len(skb); 85 gre_offset = outer_hlen - tnl_hlen; 86 skb = segs; 87 do { 88 struct gre_base_hdr *greh; 89 __be32 *pcsum; 90 91 /* Set up inner headers if we are offloading inner checksum */ 92 if (skb->ip_summed == CHECKSUM_PARTIAL) { 93 skb_reset_inner_headers(skb); 94 skb->encapsulation = 1; 95 } 96 97 skb->mac_len = mac_len; 98 skb->protocol = protocol; 99 100 __skb_push(skb, outer_hlen); 101 skb_reset_mac_header(skb); 102 skb_set_network_header(skb, mac_len); 103 skb_set_transport_header(skb, gre_offset); 104 105 if (!need_csum) 106 continue; 107 108 greh = (struct gre_base_hdr *)skb_transport_header(skb); 109 pcsum = (__be32 *)(greh + 1); 110 111 *pcsum = 0; 112 *(__sum16 *)pcsum = gso_make_checksum(skb, 0); 113 } while ((skb = skb->next)); 114 out: 115 return segs; 116 } 117 118 static struct sk_buff **gre_gro_receive(struct sk_buff **head, 119 struct sk_buff *skb) 120 { 121 struct sk_buff **pp = NULL; 122 struct sk_buff *p; 123 const struct gre_base_hdr *greh; 124 unsigned int hlen, grehlen; 125 unsigned int off; 126 int flush = 1; 127 struct packet_offload *ptype; 128 __be16 type; 129 130 if (NAPI_GRO_CB(skb)->encap_mark) 131 goto out; 132 133 NAPI_GRO_CB(skb)->encap_mark = 1; 134 135 off = skb_gro_offset(skb); 136 hlen = off + sizeof(*greh); 137 greh = skb_gro_header_fast(skb, off); 138 if (skb_gro_header_hard(skb, hlen)) { 139 greh = skb_gro_header_slow(skb, hlen, off); 140 if (unlikely(!greh)) 141 goto out; 142 } 143 144 /* Only support version 0 and K (key), C (csum) flags. Note that 145 * although the support for the S (seq#) flag can be added easily 146 * for GRO, this is problematic for GSO hence can not be enabled 147 * here because a GRO pkt may end up in the forwarding path, thus 148 * requiring GSO support to break it up correctly. 149 */ 150 if ((greh->flags & ~(GRE_KEY|GRE_CSUM)) != 0) 151 goto out; 152 153 /* We can only support GRE_CSUM if we can track the location of 154 * the GRE header. In the case of FOU/GUE we cannot because the 155 * outer UDP header displaces the GRE header leaving us in a state 156 * of limbo. 157 */ 158 if ((greh->flags & GRE_CSUM) && NAPI_GRO_CB(skb)->is_fou) 159 goto out; 160 161 type = greh->protocol; 162 163 rcu_read_lock(); 164 ptype = gro_find_receive_by_type(type); 165 if (!ptype) 166 goto out_unlock; 167 168 grehlen = GRE_HEADER_SECTION; 169 170 if (greh->flags & GRE_KEY) 171 grehlen += GRE_HEADER_SECTION; 172 173 if (greh->flags & GRE_CSUM) 174 grehlen += GRE_HEADER_SECTION; 175 176 hlen = off + grehlen; 177 if (skb_gro_header_hard(skb, hlen)) { 178 greh = skb_gro_header_slow(skb, hlen, off); 179 if (unlikely(!greh)) 180 goto out_unlock; 181 } 182 183 /* Don't bother verifying checksum if we're going to flush anyway. */ 184 if ((greh->flags & GRE_CSUM) && !NAPI_GRO_CB(skb)->flush) { 185 if (skb_gro_checksum_simple_validate(skb)) 186 goto out_unlock; 187 188 skb_gro_checksum_try_convert(skb, IPPROTO_GRE, 0, 189 null_compute_pseudo); 190 } 191 192 for (p = *head; p; p = p->next) { 193 const struct gre_base_hdr *greh2; 194 195 if (!NAPI_GRO_CB(p)->same_flow) 196 continue; 197 198 /* The following checks are needed to ensure only pkts 199 * from the same tunnel are considered for aggregation. 200 * The criteria for "the same tunnel" includes: 201 * 1) same version (we only support version 0 here) 202 * 2) same protocol (we only support ETH_P_IP for now) 203 * 3) same set of flags 204 * 4) same key if the key field is present. 205 */ 206 greh2 = (struct gre_base_hdr *)(p->data + off); 207 208 if (greh2->flags != greh->flags || 209 greh2->protocol != greh->protocol) { 210 NAPI_GRO_CB(p)->same_flow = 0; 211 continue; 212 } 213 if (greh->flags & GRE_KEY) { 214 /* compare keys */ 215 if (*(__be32 *)(greh2+1) != *(__be32 *)(greh+1)) { 216 NAPI_GRO_CB(p)->same_flow = 0; 217 continue; 218 } 219 } 220 } 221 222 skb_gro_pull(skb, grehlen); 223 224 /* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/ 225 skb_gro_postpull_rcsum(skb, greh, grehlen); 226 227 pp = ptype->callbacks.gro_receive(head, skb); 228 flush = 0; 229 230 out_unlock: 231 rcu_read_unlock(); 232 out: 233 NAPI_GRO_CB(skb)->flush |= flush; 234 235 return pp; 236 } 237 238 static int gre_gro_complete(struct sk_buff *skb, int nhoff) 239 { 240 struct gre_base_hdr *greh = (struct gre_base_hdr *)(skb->data + nhoff); 241 struct packet_offload *ptype; 242 unsigned int grehlen = sizeof(*greh); 243 int err = -ENOENT; 244 __be16 type; 245 246 skb->encapsulation = 1; 247 skb_shinfo(skb)->gso_type = SKB_GSO_GRE; 248 249 type = greh->protocol; 250 if (greh->flags & GRE_KEY) 251 grehlen += GRE_HEADER_SECTION; 252 253 if (greh->flags & GRE_CSUM) 254 grehlen += GRE_HEADER_SECTION; 255 256 rcu_read_lock(); 257 ptype = gro_find_complete_by_type(type); 258 if (ptype) 259 err = ptype->callbacks.gro_complete(skb, nhoff + grehlen); 260 261 rcu_read_unlock(); 262 263 skb_set_inner_mac_header(skb, nhoff + grehlen); 264 265 return err; 266 } 267 268 static const struct net_offload gre_offload = { 269 .callbacks = { 270 .gso_segment = gre_gso_segment, 271 .gro_receive = gre_gro_receive, 272 .gro_complete = gre_gro_complete, 273 }, 274 }; 275 276 static int __init gre_offload_init(void) 277 { 278 return inet_add_offload(&gre_offload, IPPROTO_GRE); 279 } 280 device_initcall(gre_offload_init); 281