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Linux/net/ipv4/udp_offload.c

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  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 struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
 29         netdev_features_t features,
 30         struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
 31                                              netdev_features_t features),
 32         __be16 new_protocol, bool is_ipv6)
 33 {
 34         struct sk_buff *segs = ERR_PTR(-EINVAL);
 35         u16 mac_offset = skb->mac_header;
 36         int mac_len = skb->mac_len;
 37         int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
 38         __be16 protocol = skb->protocol;
 39         netdev_features_t enc_features;
 40         int udp_offset, outer_hlen;
 41         unsigned int oldlen;
 42         bool need_csum = !!(skb_shinfo(skb)->gso_type &
 43                             SKB_GSO_UDP_TUNNEL_CSUM);
 44         bool remcsum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TUNNEL_REMCSUM);
 45         bool offload_csum = false, dont_encap = (need_csum || remcsum);
 46 
 47         oldlen = (u16)~skb->len;
 48 
 49         if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
 50                 goto out;
 51 
 52         skb->encapsulation = 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 = new_protocol;
 58         skb->encap_hdr_csum = need_csum;
 59         skb->remcsum_offload = remcsum;
 60 
 61         /* Try to offload checksum if possible */
 62         offload_csum = !!(need_csum &&
 63                           (skb->dev->features &
 64                            (is_ipv6 ? NETIF_F_V6_CSUM : NETIF_F_V4_CSUM)));
 65 
 66         /* segment inner packet. */
 67         enc_features = skb->dev->hw_enc_features & features;
 68         segs = gso_inner_segment(skb, enc_features);
 69         if (IS_ERR_OR_NULL(segs)) {
 70                 skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
 71                                      mac_len);
 72                 goto out;
 73         }
 74 
 75         outer_hlen = skb_tnl_header_len(skb);
 76         udp_offset = outer_hlen - tnl_hlen;
 77         skb = segs;
 78         do {
 79                 struct udphdr *uh;
 80                 int len;
 81                 __be32 delta;
 82 
 83                 if (dont_encap) {
 84                         skb->encapsulation = 0;
 85                         skb->ip_summed = CHECKSUM_NONE;
 86                 } else {
 87                         /* Only set up inner headers if we might be offloading
 88                          * inner checksum.
 89                          */
 90                         skb_reset_inner_headers(skb);
 91                         skb->encapsulation = 1;
 92                 }
 93 
 94                 skb->mac_len = mac_len;
 95                 skb->protocol = protocol;
 96 
 97                 skb_push(skb, outer_hlen);
 98                 skb_reset_mac_header(skb);
 99                 skb_set_network_header(skb, mac_len);
100                 skb_set_transport_header(skb, udp_offset);
101                 len = skb->len - udp_offset;
102                 uh = udp_hdr(skb);
103                 uh->len = htons(len);
104 
105                 if (!need_csum)
106                         continue;
107 
108                 delta = htonl(oldlen + len);
109 
110                 uh->check = ~csum_fold((__force __wsum)
111                                        ((__force u32)uh->check +
112                                         (__force u32)delta));
113                 if (offload_csum) {
114                         skb->ip_summed = CHECKSUM_PARTIAL;
115                         skb->csum_start = skb_transport_header(skb) - skb->head;
116                         skb->csum_offset = offsetof(struct udphdr, check);
117                 } else if (remcsum) {
118                         /* Need to calculate checksum from scratch,
119                          * inner checksums are never when doing
120                          * remote_checksum_offload.
121                          */
122 
123                         skb->csum = skb_checksum(skb, udp_offset,
124                                                  skb->len - udp_offset,
125                                                  0);
126                         uh->check = csum_fold(skb->csum);
127                         if (uh->check == 0)
128                                 uh->check = CSUM_MANGLED_0;
129                 } else {
130                         uh->check = gso_make_checksum(skb, ~uh->check);
131 
132                         if (uh->check == 0)
133                                 uh->check = CSUM_MANGLED_0;
134                 }
135         } while ((skb = skb->next));
136 out:
137         return segs;
138 }
139 
140 struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
141                                        netdev_features_t features,
142                                        bool is_ipv6)
143 {
144         __be16 protocol = skb->protocol;
145         const struct net_offload **offloads;
146         const struct net_offload *ops;
147         struct sk_buff *segs = ERR_PTR(-EINVAL);
148         struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
149                                              netdev_features_t features);
150 
151         rcu_read_lock();
152 
153         switch (skb->inner_protocol_type) {
154         case ENCAP_TYPE_ETHER:
155                 protocol = skb->inner_protocol;
156                 gso_inner_segment = skb_mac_gso_segment;
157                 break;
158         case ENCAP_TYPE_IPPROTO:
159                 offloads = is_ipv6 ? inet6_offloads : inet_offloads;
160                 ops = rcu_dereference(offloads[skb->inner_ipproto]);
161                 if (!ops || !ops->callbacks.gso_segment)
162                         goto out_unlock;
163                 gso_inner_segment = ops->callbacks.gso_segment;
164                 break;
165         default:
166                 goto out_unlock;
167         }
168 
169         segs = __skb_udp_tunnel_segment(skb, features, gso_inner_segment,
170                                         protocol, is_ipv6);
171 
172 out_unlock:
173         rcu_read_unlock();
174 
175         return segs;
176 }
177 
178 static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
179                                          netdev_features_t features)
180 {
181         struct sk_buff *segs = ERR_PTR(-EINVAL);
182         unsigned int mss;
183         __wsum csum;
184         struct udphdr *uh;
185         struct iphdr *iph;
186 
187         if (skb->encapsulation &&
188             (skb_shinfo(skb)->gso_type &
189              (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))) {
190                 segs = skb_udp_tunnel_segment(skb, features, false);
191                 goto out;
192         }
193 
194         if (!pskb_may_pull(skb, sizeof(struct udphdr)))
195                 goto out;
196 
197         mss = skb_shinfo(skb)->gso_size;
198         if (unlikely(skb->len <= mss))
199                 goto out;
200 
201         if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
202                 /* Packet is from an untrusted source, reset gso_segs. */
203                 int type = skb_shinfo(skb)->gso_type;
204 
205                 if (unlikely(type & ~(SKB_GSO_UDP | SKB_GSO_DODGY |
206                                       SKB_GSO_UDP_TUNNEL |
207                                       SKB_GSO_UDP_TUNNEL_CSUM |
208                                       SKB_GSO_TUNNEL_REMCSUM |
209                                       SKB_GSO_IPIP |
210                                       SKB_GSO_GRE | SKB_GSO_GRE_CSUM) ||
211                              !(type & (SKB_GSO_UDP))))
212                         goto out;
213 
214                 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
215 
216                 segs = NULL;
217                 goto out;
218         }
219 
220         /* Do software UFO. Complete and fill in the UDP checksum as
221          * HW cannot do checksum of UDP packets sent as multiple
222          * IP fragments.
223          */
224 
225         uh = udp_hdr(skb);
226         iph = ip_hdr(skb);
227 
228         uh->check = 0;
229         csum = skb_checksum(skb, 0, skb->len, 0);
230         uh->check = udp_v4_check(skb->len, iph->saddr, iph->daddr, csum);
231         if (uh->check == 0)
232                 uh->check = CSUM_MANGLED_0;
233 
234         skb->ip_summed = CHECKSUM_NONE;
235 
236         /* Fragment the skb. IP headers of the fragments are updated in
237          * inet_gso_segment()
238          */
239         segs = skb_segment(skb, features);
240 out:
241         return segs;
242 }
243 
244 int udp_add_offload(struct udp_offload *uo)
245 {
246         struct udp_offload_priv *new_offload = kzalloc(sizeof(*new_offload), GFP_ATOMIC);
247 
248         if (!new_offload)
249                 return -ENOMEM;
250 
251         new_offload->offload = uo;
252 
253         spin_lock(&udp_offload_lock);
254         new_offload->next = udp_offload_base;
255         rcu_assign_pointer(udp_offload_base, new_offload);
256         spin_unlock(&udp_offload_lock);
257 
258         return 0;
259 }
260 EXPORT_SYMBOL(udp_add_offload);
261 
262 static void udp_offload_free_routine(struct rcu_head *head)
263 {
264         struct udp_offload_priv *ou_priv = container_of(head, struct udp_offload_priv, rcu);
265         kfree(ou_priv);
266 }
267 
268 void udp_del_offload(struct udp_offload *uo)
269 {
270         struct udp_offload_priv __rcu **head = &udp_offload_base;
271         struct udp_offload_priv *uo_priv;
272 
273         spin_lock(&udp_offload_lock);
274 
275         uo_priv = udp_deref_protected(*head);
276         for (; uo_priv != NULL;
277              uo_priv = udp_deref_protected(*head)) {
278                 if (uo_priv->offload == uo) {
279                         rcu_assign_pointer(*head,
280                                            udp_deref_protected(uo_priv->next));
281                         goto unlock;
282                 }
283                 head = &uo_priv->next;
284         }
285         pr_warn("udp_del_offload: didn't find offload for port %d\n", ntohs(uo->port));
286 unlock:
287         spin_unlock(&udp_offload_lock);
288         if (uo_priv)
289                 call_rcu(&uo_priv->rcu, udp_offload_free_routine);
290 }
291 EXPORT_SYMBOL(udp_del_offload);
292 
293 struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb,
294                                  struct udphdr *uh)
295 {
296         struct udp_offload_priv *uo_priv;
297         struct sk_buff *p, **pp = NULL;
298         struct udphdr *uh2;
299         unsigned int off = skb_gro_offset(skb);
300         int flush = 1;
301 
302         if (NAPI_GRO_CB(skb)->udp_mark ||
303             (skb->ip_summed != CHECKSUM_PARTIAL &&
304              NAPI_GRO_CB(skb)->csum_cnt == 0 &&
305              !NAPI_GRO_CB(skb)->csum_valid))
306                 goto out;
307 
308         /* mark that this skb passed once through the udp gro layer */
309         NAPI_GRO_CB(skb)->udp_mark = 1;
310 
311         rcu_read_lock();
312         uo_priv = rcu_dereference(udp_offload_base);
313         for (; uo_priv != NULL; uo_priv = rcu_dereference(uo_priv->next)) {
314                 if (uo_priv->offload->port == uh->dest &&
315                     uo_priv->offload->callbacks.gro_receive)
316                         goto unflush;
317         }
318         goto out_unlock;
319 
320 unflush:
321         flush = 0;
322 
323         for (p = *head; p; p = p->next) {
324                 if (!NAPI_GRO_CB(p)->same_flow)
325                         continue;
326 
327                 uh2 = (struct udphdr   *)(p->data + off);
328 
329                 /* Match ports and either checksums are either both zero
330                  * or nonzero.
331                  */
332                 if ((*(u32 *)&uh->source != *(u32 *)&uh2->source) ||
333                     (!uh->check ^ !uh2->check)) {
334                         NAPI_GRO_CB(p)->same_flow = 0;
335                         continue;
336                 }
337         }
338 
339         skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */
340         skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr));
341         NAPI_GRO_CB(skb)->proto = uo_priv->offload->ipproto;
342         pp = uo_priv->offload->callbacks.gro_receive(head, skb,
343                                                      uo_priv->offload);
344 
345 out_unlock:
346         rcu_read_unlock();
347 out:
348         NAPI_GRO_CB(skb)->flush |= flush;
349         return pp;
350 }
351 
352 static struct sk_buff **udp4_gro_receive(struct sk_buff **head,
353                                          struct sk_buff *skb)
354 {
355         struct udphdr *uh = udp_gro_udphdr(skb);
356 
357         if (unlikely(!uh))
358                 goto flush;
359 
360         /* Don't bother verifying checksum if we're going to flush anyway. */
361         if (NAPI_GRO_CB(skb)->flush)
362                 goto skip;
363 
364         if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
365                                                  inet_gro_compute_pseudo))
366                 goto flush;
367         else if (uh->check)
368                 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
369                                              inet_gro_compute_pseudo);
370 skip:
371         NAPI_GRO_CB(skb)->is_ipv6 = 0;
372         return udp_gro_receive(head, skb, uh);
373 
374 flush:
375         NAPI_GRO_CB(skb)->flush = 1;
376         return NULL;
377 }
378 
379 int udp_gro_complete(struct sk_buff *skb, int nhoff)
380 {
381         struct udp_offload_priv *uo_priv;
382         __be16 newlen = htons(skb->len - nhoff);
383         struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
384         int err = -ENOSYS;
385 
386         uh->len = newlen;
387 
388         rcu_read_lock();
389 
390         uo_priv = rcu_dereference(udp_offload_base);
391         for (; uo_priv != NULL; uo_priv = rcu_dereference(uo_priv->next)) {
392                 if (uo_priv->offload->port == uh->dest &&
393                     uo_priv->offload->callbacks.gro_complete)
394                         break;
395         }
396 
397         if (uo_priv) {
398                 NAPI_GRO_CB(skb)->proto = uo_priv->offload->ipproto;
399                 err = uo_priv->offload->callbacks.gro_complete(skb,
400                                 nhoff + sizeof(struct udphdr),
401                                 uo_priv->offload);
402         }
403 
404         rcu_read_unlock();
405 
406         if (skb->remcsum_offload)
407                 skb_shinfo(skb)->gso_type |= SKB_GSO_TUNNEL_REMCSUM;
408 
409         skb->encapsulation = 1;
410         skb_set_inner_mac_header(skb, nhoff + sizeof(struct udphdr));
411 
412         return err;
413 }
414 
415 static int udp4_gro_complete(struct sk_buff *skb, int nhoff)
416 {
417         const struct iphdr *iph = ip_hdr(skb);
418         struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
419 
420         if (uh->check) {
421                 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
422                 uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr,
423                                           iph->daddr, 0);
424         } else {
425                 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL;
426         }
427 
428         return udp_gro_complete(skb, nhoff);
429 }
430 
431 static const struct net_offload udpv4_offload = {
432         .callbacks = {
433                 .gso_segment = udp4_ufo_fragment,
434                 .gro_receive  = udp4_gro_receive,
435                 .gro_complete = udp4_gro_complete,
436         },
437 };
438 
439 int __init udpv4_offload_init(void)
440 {
441         return inet_add_offload(&udpv4_offload, IPPROTO_UDP);
442 }
443 

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