LCOV - code coverage report
Current view: top level - net/ipv4 - gre_offload.c (source / functions) Hit Total Coverage
Test: landlock.info Lines: 4 157 2.5 %
Date: 2021-04-22 12:43:58 Functions: 1 4 25.0 %

          Line data    Source code
       1             : // SPDX-License-Identifier: GPL-2.0-or-later
       2             : /*
       3             :  *      IPV4 GSO/GRO offload support
       4             :  *      Linux INET implementation
       5             :  *
       6             :  *      GRE GSO support
       7             :  */
       8             : 
       9             : #include <linux/skbuff.h>
      10             : #include <linux/init.h>
      11             : #include <net/protocol.h>
      12             : #include <net/gre.h>
      13             : 
      14           0 : static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
      15             :                                        netdev_features_t features)
      16             : {
      17           0 :         int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
      18           0 :         bool need_csum, offload_csum, gso_partial, need_ipsec;
      19           0 :         struct sk_buff *segs = ERR_PTR(-EINVAL);
      20           0 :         u16 mac_offset = skb->mac_header;
      21           0 :         __be16 protocol = skb->protocol;
      22           0 :         u16 mac_len = skb->mac_len;
      23           0 :         int gre_offset, outer_hlen;
      24             : 
      25           0 :         if (!skb->encapsulation)
      26           0 :                 goto out;
      27             : 
      28           0 :         if (unlikely(tnl_hlen < sizeof(struct gre_base_hdr)))
      29           0 :                 goto out;
      30             : 
      31           0 :         if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
      32           0 :                 goto out;
      33             : 
      34             :         /* setup inner skb. */
      35           0 :         skb->encapsulation = 0;
      36           0 :         SKB_GSO_CB(skb)->encap_level = 0;
      37           0 :         __skb_pull(skb, tnl_hlen);
      38           0 :         skb_reset_mac_header(skb);
      39           0 :         skb_set_network_header(skb, skb_inner_network_offset(skb));
      40           0 :         skb->mac_len = skb_inner_network_offset(skb);
      41           0 :         skb->protocol = skb->inner_protocol;
      42             : 
      43           0 :         need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_GRE_CSUM);
      44           0 :         skb->encap_hdr_csum = need_csum;
      45             : 
      46           0 :         features &= skb->dev->hw_enc_features;
      47           0 :         if (need_csum)
      48           0 :                 features &= ~NETIF_F_SCTP_CRC;
      49             : 
      50           0 :         need_ipsec = skb_dst(skb) && dst_xfrm(skb_dst(skb));
      51             :         /* Try to offload checksum if possible */
      52           0 :         offload_csum = !!(need_csum && !need_ipsec &&
      53           0 :                           (skb->dev->features & NETIF_F_HW_CSUM));
      54             : 
      55             :         /* segment inner packet. */
      56           0 :         segs = skb_mac_gso_segment(skb, features);
      57           0 :         if (IS_ERR_OR_NULL(segs)) {
      58           0 :                 skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
      59             :                                      mac_len);
      60           0 :                 goto out;
      61             :         }
      62             : 
      63           0 :         gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL);
      64             : 
      65           0 :         outer_hlen = skb_tnl_header_len(skb);
      66           0 :         gre_offset = outer_hlen - tnl_hlen;
      67           0 :         skb = segs;
      68           0 :         do {
      69           0 :                 struct gre_base_hdr *greh;
      70           0 :                 __sum16 *pcsum;
      71             : 
      72             :                 /* Set up inner headers if we are offloading inner checksum */
      73           0 :                 if (skb->ip_summed == CHECKSUM_PARTIAL) {
      74           0 :                         skb_reset_inner_headers(skb);
      75           0 :                         skb->encapsulation = 1;
      76             :                 }
      77             : 
      78           0 :                 skb->mac_len = mac_len;
      79           0 :                 skb->protocol = protocol;
      80             : 
      81           0 :                 __skb_push(skb, outer_hlen);
      82           0 :                 skb_reset_mac_header(skb);
      83           0 :                 skb_set_network_header(skb, mac_len);
      84           0 :                 skb_set_transport_header(skb, gre_offset);
      85             : 
      86           0 :                 if (!need_csum)
      87           0 :                         continue;
      88             : 
      89           0 :                 greh = (struct gre_base_hdr *)skb_transport_header(skb);
      90           0 :                 pcsum = (__sum16 *)(greh + 1);
      91             : 
      92           0 :                 if (gso_partial && skb_is_gso(skb)) {
      93           0 :                         unsigned int partial_adj;
      94             : 
      95             :                         /* Adjust checksum to account for the fact that
      96             :                          * the partial checksum is based on actual size
      97             :                          * whereas headers should be based on MSS size.
      98             :                          */
      99           0 :                         partial_adj = skb->len + skb_headroom(skb) -
     100           0 :                                       SKB_GSO_CB(skb)->data_offset -
     101           0 :                                       skb_shinfo(skb)->gso_size;
     102           0 :                         *pcsum = ~csum_fold((__force __wsum)htonl(partial_adj));
     103             :                 } else {
     104           0 :                         *pcsum = 0;
     105             :                 }
     106             : 
     107           0 :                 *(pcsum + 1) = 0;
     108           0 :                 if (skb->encapsulation || !offload_csum) {
     109           0 :                         *pcsum = gso_make_checksum(skb, 0);
     110             :                 } else {
     111           0 :                         skb->ip_summed = CHECKSUM_PARTIAL;
     112           0 :                         skb->csum_start = skb_transport_header(skb) - skb->head;
     113           0 :                         skb->csum_offset = sizeof(*greh);
     114             :                 }
     115           0 :         } while ((skb = skb->next));
     116           0 : out:
     117           0 :         return segs;
     118             : }
     119             : 
     120           0 : static struct sk_buff *gre_gro_receive(struct list_head *head,
     121             :                                        struct sk_buff *skb)
     122             : {
     123           0 :         struct sk_buff *pp = NULL;
     124           0 :         struct sk_buff *p;
     125           0 :         const struct gre_base_hdr *greh;
     126           0 :         unsigned int hlen, grehlen;
     127           0 :         unsigned int off;
     128           0 :         int flush = 1;
     129           0 :         struct packet_offload *ptype;
     130           0 :         __be16 type;
     131             : 
     132           0 :         if (NAPI_GRO_CB(skb)->encap_mark)
     133           0 :                 goto out;
     134             : 
     135           0 :         NAPI_GRO_CB(skb)->encap_mark = 1;
     136             : 
     137           0 :         off = skb_gro_offset(skb);
     138           0 :         hlen = off + sizeof(*greh);
     139           0 :         greh = skb_gro_header_fast(skb, off);
     140           0 :         if (skb_gro_header_hard(skb, hlen)) {
     141           0 :                 greh = skb_gro_header_slow(skb, hlen, off);
     142           0 :                 if (unlikely(!greh))
     143           0 :                         goto out;
     144             :         }
     145             : 
     146             :         /* Only support version 0 and K (key), C (csum) flags. Note that
     147             :          * although the support for the S (seq#) flag can be added easily
     148             :          * for GRO, this is problematic for GSO hence can not be enabled
     149             :          * here because a GRO pkt may end up in the forwarding path, thus
     150             :          * requiring GSO support to break it up correctly.
     151             :          */
     152           0 :         if ((greh->flags & ~(GRE_KEY|GRE_CSUM)) != 0)
     153           0 :                 goto out;
     154             : 
     155             :         /* We can only support GRE_CSUM if we can track the location of
     156             :          * the GRE header.  In the case of FOU/GUE we cannot because the
     157             :          * outer UDP header displaces the GRE header leaving us in a state
     158             :          * of limbo.
     159             :          */
     160           0 :         if ((greh->flags & GRE_CSUM) && NAPI_GRO_CB(skb)->is_fou)
     161           0 :                 goto out;
     162             : 
     163           0 :         type = greh->protocol;
     164             : 
     165           0 :         rcu_read_lock();
     166           0 :         ptype = gro_find_receive_by_type(type);
     167           0 :         if (!ptype)
     168           0 :                 goto out_unlock;
     169             : 
     170           0 :         grehlen = GRE_HEADER_SECTION;
     171             : 
     172           0 :         if (greh->flags & GRE_KEY)
     173           0 :                 grehlen += GRE_HEADER_SECTION;
     174             : 
     175           0 :         if (greh->flags & GRE_CSUM)
     176           0 :                 grehlen += GRE_HEADER_SECTION;
     177             : 
     178           0 :         hlen = off + grehlen;
     179           0 :         if (skb_gro_header_hard(skb, hlen)) {
     180           0 :                 greh = skb_gro_header_slow(skb, hlen, off);
     181           0 :                 if (unlikely(!greh))
     182           0 :                         goto out_unlock;
     183             :         }
     184             : 
     185             :         /* Don't bother verifying checksum if we're going to flush anyway. */
     186           0 :         if ((greh->flags & GRE_CSUM) && !NAPI_GRO_CB(skb)->flush) {
     187           0 :                 if (skb_gro_checksum_simple_validate(skb))
     188           0 :                         goto out_unlock;
     189             : 
     190           0 :                 skb_gro_checksum_try_convert(skb, IPPROTO_GRE,
     191             :                                              null_compute_pseudo);
     192             :         }
     193             : 
     194           0 :         list_for_each_entry(p, head, list) {
     195           0 :                 const struct gre_base_hdr *greh2;
     196             : 
     197           0 :                 if (!NAPI_GRO_CB(p)->same_flow)
     198           0 :                         continue;
     199             : 
     200             :                 /* The following checks are needed to ensure only pkts
     201             :                  * from the same tunnel are considered for aggregation.
     202             :                  * The criteria for "the same tunnel" includes:
     203             :                  * 1) same version (we only support version 0 here)
     204             :                  * 2) same protocol (we only support ETH_P_IP for now)
     205             :                  * 3) same set of flags
     206             :                  * 4) same key if the key field is present.
     207             :                  */
     208           0 :                 greh2 = (struct gre_base_hdr *)(p->data + off);
     209             : 
     210           0 :                 if (greh2->flags != greh->flags ||
     211           0 :                     greh2->protocol != greh->protocol) {
     212           0 :                         NAPI_GRO_CB(p)->same_flow = 0;
     213           0 :                         continue;
     214             :                 }
     215           0 :                 if (greh->flags & GRE_KEY) {
     216             :                         /* compare keys */
     217           0 :                         if (*(__be32 *)(greh2+1) != *(__be32 *)(greh+1)) {
     218           0 :                                 NAPI_GRO_CB(p)->same_flow = 0;
     219           0 :                                 continue;
     220             :                         }
     221             :                 }
     222             :         }
     223             : 
     224           0 :         skb_gro_pull(skb, grehlen);
     225             : 
     226             :         /* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/
     227           0 :         skb_gro_postpull_rcsum(skb, greh, grehlen);
     228             : 
     229           0 :         pp = call_gro_receive(ptype->callbacks.gro_receive, head, skb);
     230           0 :         flush = 0;
     231             : 
     232           0 : out_unlock:
     233           0 :         rcu_read_unlock();
     234           0 : out:
     235           0 :         skb_gro_flush_final(skb, pp, flush);
     236             : 
     237           0 :         return pp;
     238             : }
     239             : 
     240           0 : static int gre_gro_complete(struct sk_buff *skb, int nhoff)
     241             : {
     242           0 :         struct gre_base_hdr *greh = (struct gre_base_hdr *)(skb->data + nhoff);
     243           0 :         struct packet_offload *ptype;
     244           0 :         unsigned int grehlen = sizeof(*greh);
     245           0 :         int err = -ENOENT;
     246           0 :         __be16 type;
     247             : 
     248           0 :         skb->encapsulation = 1;
     249           0 :         skb_shinfo(skb)->gso_type = SKB_GSO_GRE;
     250             : 
     251           0 :         type = greh->protocol;
     252           0 :         if (greh->flags & GRE_KEY)
     253           0 :                 grehlen += GRE_HEADER_SECTION;
     254             : 
     255           0 :         if (greh->flags & GRE_CSUM)
     256           0 :                 grehlen += GRE_HEADER_SECTION;
     257             : 
     258           0 :         rcu_read_lock();
     259           0 :         ptype = gro_find_complete_by_type(type);
     260           0 :         if (ptype)
     261           0 :                 err = ptype->callbacks.gro_complete(skb, nhoff + grehlen);
     262             : 
     263           0 :         rcu_read_unlock();
     264             : 
     265           0 :         skb_set_inner_mac_header(skb, nhoff + grehlen);
     266             : 
     267           0 :         return err;
     268             : }
     269             : 
     270             : static const struct net_offload gre_offload = {
     271             :         .callbacks = {
     272             :                 .gso_segment = gre_gso_segment,
     273             :                 .gro_receive = gre_gro_receive,
     274             :                 .gro_complete = gre_gro_complete,
     275             :         },
     276             : };
     277             : 
     278           1 : static int __init gre_offload_init(void)
     279             : {
     280           1 :         int err;
     281             : 
     282           1 :         err = inet_add_offload(&gre_offload, IPPROTO_GRE);
     283             : #if IS_ENABLED(CONFIG_IPV6)
     284             :         if (err)
     285             :                 return err;
     286             : 
     287             :         err = inet6_add_offload(&gre_offload, IPPROTO_GRE);
     288             :         if (err)
     289             :                 inet_del_offload(&gre_offload, IPPROTO_GRE);
     290             : #endif
     291             : 
     292           1 :         return err;
     293             : }
     294             : device_initcall(gre_offload_init);

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