net/sctp/offload.c

   1 /*
   2  * sctp_offload - GRO/GSO Offloading for SCTP
   3  *
   4  * Copyright (C) 2015, Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  */
  16
  17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  18
  19 #include <linux/kernel.h>
  20 #include <linux/kprobes.h>
  21 #include <linux/socket.h>
  22 #include <linux/sctp.h>
  23 #include <linux/proc_fs.h>
  24 #include <linux/vmalloc.h>
  25 #include <linux/module.h>
  26 #include <linux/kfifo.h>
  27 #include <linux/time.h>
  28 #include <net/net_namespace.h>
  29
  30 #include <linux/skbuff.h>
  31 #include <net/sctp/sctp.h>
  32 #include <net/sctp/checksum.h>
  33 #include <net/protocol.h>
  34
  35 static __le32 sctp_gso_make_checksum(struct sk_buff *skb)
  36 {
  37         skb->ip_summed = CHECKSUM_NONE;
  38         skb->csum_not_inet = 0;
  39         gso_reset_checksum(skb, ~0);
  40         return sctp_compute_cksum(skb, skb_transport_offset(skb));
  41 }
  42
  43 static struct sk_buff *sctp_gso_segment(struct sk_buff *skb,
  44                                         netdev_features_t features)
  45 {
  46         struct sk_buff *segs = ERR_PTR(-EINVAL);
  47         struct sctphdr *sh;
  48
  49         if (!skb_is_gso_sctp(skb))
  50                 goto out;
  51
  52         sh = sctp_hdr(skb);
  53         if (!pskb_may_pull(skb, sizeof(*sh)))
  54                 goto out;
  55
  56         __skb_pull(skb, sizeof(*sh));
  57
  58         if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
  59                 /* Packet is from an untrusted source, reset gso_segs. */
  60                 struct skb_shared_info *pinfo = skb_shinfo(skb);
  61                 struct sk_buff *frag_iter;
  62
  63                 pinfo->gso_segs = 0;
  64                 if (skb->len != skb->data_len) {
  65                         /* Means we have chunks in here too */
  66                         pinfo->gso_segs++;
  67                 }
  68
  69                 skb_walk_frags(skb, frag_iter)
  70                         pinfo->gso_segs++;
  71
  72                 segs = NULL;
  73                 goto out;
  74         }
  75
  76         segs = skb_segment(skb, features | NETIF_F_HW_CSUM | NETIF_F_SG);
  77         if (IS_ERR(segs))
  78                 goto out;
  79
  80         /* All that is left is update SCTP CRC if necessary */
  81         if (!(features & NETIF_F_SCTP_CRC)) {
  82                 for (skb = segs; skb; skb = skb->next) {
  83                         if (skb->ip_summed == CHECKSUM_PARTIAL) {
  84                                 sh = sctp_hdr(skb);
  85                                 sh->checksum = sctp_gso_make_checksum(skb);
  86                         }
  87                 }
  88         }
  89
  90 out:
  91         return segs;
  92 }
  93
  94 static const struct net_offload sctp_offload = {
  95         .callbacks = {
  96                 .gso_segment = sctp_gso_segment,
  97         },
  98 };
  99
 100 static const struct net_offload sctp6_offload = {
 101         .callbacks = {
 102                 .gso_segment = sctp_gso_segment,
 103         },
 104 };
 105
 106 static const struct skb_checksum_ops crc32c_csum_ops = {
 107         .update  = sctp_csum_update,
 108         .combine = sctp_csum_combine,
 109 };
 110
 111 int __init sctp_offload_init(void)
 112 {
 113         int ret;
 114
 115         ret = inet_add_offload(&sctp_offload, IPPROTO_SCTP);
 116         if (ret)
 117                 goto out;
 118
 119         ret = inet6_add_offload(&sctp6_offload, IPPROTO_SCTP);
 120         if (ret)
 121                 goto ipv4;
 122
 123         crc32c_csum_stub = &crc32c_csum_ops;
 124         return ret;
 125
 126 ipv4:
 127         inet_del_offload(&sctp_offload, IPPROTO_SCTP);
 128 out:
 129         return ret;
 130 }