net/ipv4/udp_offload.c

   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  *      UDPv4 GSO support
  11  */
  12
  13 #include <linux/skbuff.h>
  14 #include <net/udp.h>
  15 #include <net/protocol.h>
  16
  17 static DEFINE_SPINLOCK(udp_offload_lock);
  18 static struct udp_offload_priv __rcu *udp_offload_base __read_mostly;
  19
  20 #define udp_deref_protected(X) rcu_dereference_protected(X, lockdep_is_held(&udp_offload_lock))
  21
  22 struct udp_offload_priv {
  23         struct udp_offload      *offload;
  24         struct rcu_head         rcu;
  25         struct udp_offload_priv __rcu *next;
  26 };
  27
  28 static int udp4_ufo_send_check(struct sk_buff *skb)
  29 {
  30         if (!pskb_may_pull(skb, sizeof(struct udphdr)))
  31                 return -EINVAL;
  32
  33         if (likely(!skb->encapsulation)) {
  34                 const struct iphdr *iph;
  35                 struct udphdr *uh;
  36
  37                 iph = ip_hdr(skb);
  38                 uh = udp_hdr(skb);
  39
  40                 uh->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr, skb->len,
  41                                 IPPROTO_UDP, 0);
  42                 skb->csum_start = skb_transport_header(skb) - skb->head;
  43                 skb->csum_offset = offsetof(struct udphdr, check);
  44                 skb->ip_summed = CHECKSUM_PARTIAL;
  45         }
  46
  47         return 0;
  48 }
  49
  50 static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
  51                                          netdev_features_t features)
  52 {
  53         struct sk_buff *segs = ERR_PTR(-EINVAL);
  54         unsigned int mss;
  55         int offset;
  56         __wsum csum;
  57
  58         if (skb->encapsulation &&
  59             (skb_shinfo(skb)->gso_type &
  60              (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))) {
  61                 segs = skb_udp_tunnel_segment(skb, features);
  62                 goto out;
  63         }
  64
  65         mss = skb_shinfo(skb)->gso_size;
  66         if (unlikely(skb->len <= mss))
  67                 goto out;
  68
  69         if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
  70                 /* Packet is from an untrusted source, reset gso_segs. */
  71                 int type = skb_shinfo(skb)->gso_type;
  72
  73                 if (unlikely(type & ~(SKB_GSO_UDP | SKB_GSO_DODGY |
  74                                       SKB_GSO_UDP_TUNNEL |
  75                                       SKB_GSO_UDP_TUNNEL_CSUM |
  76                                       SKB_GSO_IPIP |
  77                                       SKB_GSO_GRE | SKB_GSO_GRE_CSUM |
  78                                       SKB_GSO_MPLS) ||
  79                              !(type & (SKB_GSO_UDP))))
  80                         goto out;
  81
  82                 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
  83
  84                 segs = NULL;
  85                 goto out;
  86         }
  87
  88         /* Do software UFO. Complete and fill in the UDP checksum as
  89          * HW cannot do checksum of UDP packets sent as multiple
  90          * IP fragments.
  91          */
  92         offset = skb_checksum_start_offset(skb);
  93         csum = skb_checksum(skb, offset, skb->len - offset, 0);
  94         offset += skb->csum_offset;
  95         *(__sum16 *)(skb->data + offset) = csum_fold(csum);
  96         skb->ip_summed = CHECKSUM_NONE;
  97
  98         /* Fragment the skb. IP headers of the fragments are updated in
  99          * inet_gso_segment()
 100          */
 101         segs = skb_segment(skb, features);
 102 out:
 103         return segs;
 104 }
 105
 106 int udp_add_offload(struct udp_offload *uo)
 107 {
 108         struct udp_offload_priv *new_offload = kzalloc(sizeof(*new_offload), GFP_ATOMIC);
 109
 110         if (!new_offload)
 111                 return -ENOMEM;
 112
 113         new_offload->offload = uo;
 114
 115         spin_lock(&udp_offload_lock);
 116         new_offload->next = udp_offload_base;
 117         rcu_assign_pointer(udp_offload_base, new_offload);
 118         spin_unlock(&udp_offload_lock);
 119
 120         return 0;
 121 }
 122 EXPORT_SYMBOL(udp_add_offload);
 123
 124 static void udp_offload_free_routine(struct rcu_head *head)
 125 {
 126         struct udp_offload_priv *ou_priv = container_of(head, struct udp_offload_priv, rcu);
 127         kfree(ou_priv);
 128 }
 129
 130 void udp_del_offload(struct udp_offload *uo)
 131 {
 132         struct udp_offload_priv __rcu **head = &udp_offload_base;
 133         struct udp_offload_priv *uo_priv;
 134
 135         spin_lock(&udp_offload_lock);
 136
 137         uo_priv = udp_deref_protected(*head);
 138         for (; uo_priv != NULL;
 139              uo_priv = udp_deref_protected(*head)) {
 140                 if (uo_priv->offload == uo) {
 141                         rcu_assign_pointer(*head,
 142                                            udp_deref_protected(uo_priv->next));
 143                         goto unlock;
 144                 }
 145                 head = &uo_priv->next;
 146         }
 147         pr_warn("udp_del_offload: didn't find offload for port %d\n", ntohs(uo->port));
 148 unlock:
 149         spin_unlock(&udp_offload_lock);
 150         if (uo_priv != NULL)
 151                 call_rcu(&uo_priv->rcu, udp_offload_free_routine);
 152 }
 153 EXPORT_SYMBOL(udp_del_offload);
 154
 155 static struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb)
 156 {
 157         struct udp_offload_priv *uo_priv;
 158         struct sk_buff *p, **pp = NULL;
 159         struct udphdr *uh, *uh2;
 160         unsigned int hlen, off;
 161         int flush = 1;
 162
 163         if (NAPI_GRO_CB(skb)->udp_mark ||
 164             (!skb->encapsulation && skb->ip_summed != CHECKSUM_COMPLETE))
 165                 goto out;
 166
 167         /* mark that this skb passed once through the udp gro layer */
 168         NAPI_GRO_CB(skb)->udp_mark = 1;
 169
 170         off  = skb_gro_offset(skb);
 171         hlen = off + sizeof(*uh);
 172         uh   = skb_gro_header_fast(skb, off);
 173         if (skb_gro_header_hard(skb, hlen)) {
 174                 uh = skb_gro_header_slow(skb, hlen, off);
 175                 if (unlikely(!uh))
 176                         goto out;
 177         }
 178
 179         rcu_read_lock();
 180         uo_priv = rcu_dereference(udp_offload_base);
 181         for (; uo_priv != NULL; uo_priv = rcu_dereference(uo_priv->next)) {
 182                 if (uo_priv->offload->port == uh->dest &&
 183                     uo_priv->offload->callbacks.gro_receive)
 184                         goto unflush;
 185         }
 186         goto out_unlock;
 187
 188 unflush:
 189         flush = 0;
 190
 191         for (p = *head; p; p = p->next) {
 192                 if (!NAPI_GRO_CB(p)->same_flow)
 193                         continue;
 194
 195                 uh2 = (struct udphdr   *)(p->data + off);
 196                 if ((*(u32 *)&uh->source != *(u32 *)&uh2->source)) {
 197                         NAPI_GRO_CB(p)->same_flow = 0;
 198                         continue;
 199                 }
 200         }
 201
 202         skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */
 203         skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr));
 204         pp = uo_priv->offload->callbacks.gro_receive(head, skb);
 205
 206 out_unlock:
 207         rcu_read_unlock();
 208 out:
 209         NAPI_GRO_CB(skb)->flush |= flush;
 210         return pp;
 211 }
 212
 213 static int udp_gro_complete(struct sk_buff *skb, int nhoff)
 214 {
 215         struct udp_offload_priv *uo_priv;
 216         __be16 newlen = htons(skb->len - nhoff);
 217         struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 218         int err = -ENOSYS;
 219
 220         uh->len = newlen;
 221
 222         rcu_read_lock();
 223
 224         uo_priv = rcu_dereference(udp_offload_base);
 225         for (; uo_priv != NULL; uo_priv = rcu_dereference(uo_priv->next)) {
 226                 if (uo_priv->offload->port == uh->dest &&
 227                     uo_priv->offload->callbacks.gro_complete)
 228                         break;
 229         }
 230
 231         if (uo_priv != NULL)
 232                 err = uo_priv->offload->callbacks.gro_complete(skb, nhoff + sizeof(struct udphdr));
 233
 234         rcu_read_unlock();
 235         return err;
 236 }
 237
 238 static const struct net_offload udpv4_offload = {
 239         .callbacks = {
 240                 .gso_send_check = udp4_ufo_send_check,
 241                 .gso_segment = udp4_ufo_fragment,
 242                 .gro_receive  = udp_gro_receive,
 243                 .gro_complete = udp_gro_complete,
 244         },
 245 };
 246
 247 int __init udpv4_offload_init(void)
 248 {
 249         return inet_add_offload(&udpv4_offload, IPPROTO_UDP);
 250 }