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