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         return sctp_compute_cksum(skb, skb_transport_offset(skb));
  40 }
  41
  42 static struct sk_buff *sctp_gso_segment(struct sk_buff *skb,
  43                                         netdev_features_t features)
  44 {
  45         struct sk_buff *segs = ERR_PTR(-EINVAL);
  46         struct sctphdr *sh;
  47
  48         if (!(skb_shinfo(skb)->gso_type & SKB_GSO_SCTP))
  49                 goto out;
  50
  51         sh = sctp_hdr(skb);
  52         if (!pskb_may_pull(skb, sizeof(*sh)))
  53                 goto out;
  54
  55         __skb_pull(skb, sizeof(*sh));
  56
  57         if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
  58                 /* Packet is from an untrusted source, reset gso_segs. */
  59                 struct skb_shared_info *pinfo = skb_shinfo(skb);
  60                 struct sk_buff *frag_iter;
  61
  62                 pinfo->gso_segs = 0;
  63                 if (skb->len != skb->data_len) {
  64                         /* Means we have chunks in here too */
  65                         pinfo->gso_segs++;
  66                 }
  67
  68                 skb_walk_frags(skb, frag_iter)
  69                         pinfo->gso_segs++;
  70
  71                 segs = NULL;
  72                 goto out;
  73         }
  74
  75         segs = skb_segment(skb, features | NETIF_F_HW_CSUM | NETIF_F_SG);
  76         if (IS_ERR(segs))
  77                 goto out;
  78
  79         /* All that is left is update SCTP CRC if necessary */
  80         if (!(features & NETIF_F_SCTP_CRC)) {
  81                 for (skb = segs; skb; skb = skb->next) {
  82                         if (skb->ip_summed == CHECKSUM_PARTIAL) {
  83                                 sh = sctp_hdr(skb);
  84                                 sh->checksum = sctp_gso_make_checksum(skb);
  85                         }
  86                 }
  87         }
  88
  89 out:
  90         return segs;
  91 }
  92
  93 static const struct net_offload sctp_offload = {
  94         .callbacks = {
  95                 .gso_segment = sctp_gso_segment,
  96         },
  97 };
  98
  99 static const struct net_offload sctp6_offload = {
 100         .callbacks = {
 101                 .gso_segment = sctp_gso_segment,
 102         },
 103 };
 104
 105 static const struct skb_checksum_ops crc32c_csum_ops = {
 106         .update  = sctp_csum_update,
 107         .combine = sctp_csum_combine,
 108 };
 109
 110 int __init sctp_offload_init(void)
 111 {
 112         int ret;
 113
 114         ret = inet_add_offload(&sctp_offload, IPPROTO_SCTP);
 115         if (ret)
 116                 goto out;
 117
 118         ret = inet6_add_offload(&sctp6_offload, IPPROTO_SCTP);
 119         if (ret)
 120                 goto ipv4;
 121
 122         crc32c_csum_stub = &crc32c_csum_ops;
 123         return ret;
 124
 125 ipv4:
 126         inet_del_offload(&sctp_offload, IPPROTO_SCTP);
 127 out:
 128         return ret;
 129 }