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