![Florian Westphal](/assets/img/avatar_default.png)
skb_gso_segment() has a 'features' argument representing offload features available to the output path. A few handlers, e.g. GRE, instead re-fetch the features of skb->dev and use those instead of the provided ones when handing encapsulation/tunnels. Depending on dev->hw_enc_features of the output device skb_gso_segment() can then return NULL even when the caller has disabled all GSO feature bits, as segmentation of inner header thinks device will take care of segmentation. This e.g. affects the tbf scheduler, which will silently drop GRE-encap GSO skbs that did not fit the remaining token quota as the segmentation does not work when device supports corresponding hw offload capabilities. Cc: Pravin B Shelar <pshelar@nicira.com> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: David S. Miller <davem@davemloft.net>
266 lines
6.2 KiB
C
266 lines
6.2 KiB
C
/*
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* IPV4 GSO/GRO offload support
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* Linux INET implementation
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* GRE GSO support
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*/
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#include <linux/skbuff.h>
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#include <linux/init.h>
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#include <net/protocol.h>
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#include <net/gre.h>
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static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
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netdev_features_t features)
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{
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struct sk_buff *segs = ERR_PTR(-EINVAL);
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netdev_features_t enc_features;
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int ghl;
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struct gre_base_hdr *greh;
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u16 mac_offset = skb->mac_header;
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int mac_len = skb->mac_len;
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__be16 protocol = skb->protocol;
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int tnl_hlen;
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bool csum;
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if (unlikely(skb_shinfo(skb)->gso_type &
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~(SKB_GSO_TCPV4 |
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SKB_GSO_TCPV6 |
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SKB_GSO_UDP |
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SKB_GSO_DODGY |
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SKB_GSO_TCP_ECN |
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SKB_GSO_GRE |
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SKB_GSO_GRE_CSUM |
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SKB_GSO_IPIP)))
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goto out;
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if (!skb->encapsulation)
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goto out;
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if (unlikely(!pskb_may_pull(skb, sizeof(*greh))))
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goto out;
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greh = (struct gre_base_hdr *)skb_transport_header(skb);
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ghl = skb_inner_network_header(skb) - skb_transport_header(skb);
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if (unlikely(ghl < sizeof(*greh)))
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goto out;
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csum = !!(greh->flags & GRE_CSUM);
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if (csum)
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skb->encap_hdr_csum = 1;
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/* setup inner skb. */
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skb->protocol = greh->protocol;
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skb->encapsulation = 0;
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if (unlikely(!pskb_may_pull(skb, ghl)))
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goto out;
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__skb_pull(skb, ghl);
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skb_reset_mac_header(skb);
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skb_set_network_header(skb, skb_inner_network_offset(skb));
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skb->mac_len = skb_inner_network_offset(skb);
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/* segment inner packet. */
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enc_features = skb->dev->hw_enc_features & features;
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segs = skb_mac_gso_segment(skb, enc_features);
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if (IS_ERR_OR_NULL(segs)) {
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skb_gso_error_unwind(skb, protocol, ghl, mac_offset, mac_len);
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goto out;
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}
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skb = segs;
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tnl_hlen = skb_tnl_header_len(skb);
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do {
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__skb_push(skb, ghl);
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if (csum) {
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__be32 *pcsum;
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if (skb_has_shared_frag(skb)) {
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int err;
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err = __skb_linearize(skb);
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if (err) {
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kfree_skb_list(segs);
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segs = ERR_PTR(err);
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goto out;
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}
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}
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skb_reset_transport_header(skb);
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greh = (struct gre_base_hdr *)
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skb_transport_header(skb);
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pcsum = (__be32 *)(greh + 1);
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*pcsum = 0;
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*(__sum16 *)pcsum = gso_make_checksum(skb, 0);
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}
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__skb_push(skb, tnl_hlen - ghl);
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skb_reset_inner_headers(skb);
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skb->encapsulation = 1;
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skb_reset_mac_header(skb);
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skb_set_network_header(skb, mac_len);
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skb->mac_len = mac_len;
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skb->protocol = protocol;
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} while ((skb = skb->next));
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out:
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return segs;
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}
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static struct sk_buff **gre_gro_receive(struct sk_buff **head,
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struct sk_buff *skb)
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{
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struct sk_buff **pp = NULL;
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struct sk_buff *p;
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const struct gre_base_hdr *greh;
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unsigned int hlen, grehlen;
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unsigned int off;
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int flush = 1;
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struct packet_offload *ptype;
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__be16 type;
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off = skb_gro_offset(skb);
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hlen = off + sizeof(*greh);
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greh = skb_gro_header_fast(skb, off);
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if (skb_gro_header_hard(skb, hlen)) {
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greh = skb_gro_header_slow(skb, hlen, off);
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if (unlikely(!greh))
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goto out;
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}
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/* Only support version 0 and K (key), C (csum) flags. Note that
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* although the support for the S (seq#) flag can be added easily
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* for GRO, this is problematic for GSO hence can not be enabled
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* here because a GRO pkt may end up in the forwarding path, thus
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* requiring GSO support to break it up correctly.
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*/
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if ((greh->flags & ~(GRE_KEY|GRE_CSUM)) != 0)
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goto out;
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type = greh->protocol;
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rcu_read_lock();
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ptype = gro_find_receive_by_type(type);
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if (ptype == NULL)
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goto out_unlock;
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grehlen = GRE_HEADER_SECTION;
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if (greh->flags & GRE_KEY)
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grehlen += GRE_HEADER_SECTION;
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if (greh->flags & GRE_CSUM)
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grehlen += GRE_HEADER_SECTION;
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hlen = off + grehlen;
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if (skb_gro_header_hard(skb, hlen)) {
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greh = skb_gro_header_slow(skb, hlen, off);
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if (unlikely(!greh))
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goto out_unlock;
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}
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/* Don't bother verifying checksum if we're going to flush anyway. */
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if ((greh->flags & GRE_CSUM) && !NAPI_GRO_CB(skb)->flush) {
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if (skb_gro_checksum_simple_validate(skb))
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goto out_unlock;
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skb_gro_checksum_try_convert(skb, IPPROTO_GRE, 0,
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null_compute_pseudo);
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}
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flush = 0;
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for (p = *head; p; p = p->next) {
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const struct gre_base_hdr *greh2;
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if (!NAPI_GRO_CB(p)->same_flow)
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continue;
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/* The following checks are needed to ensure only pkts
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* from the same tunnel are considered for aggregation.
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* The criteria for "the same tunnel" includes:
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* 1) same version (we only support version 0 here)
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* 2) same protocol (we only support ETH_P_IP for now)
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* 3) same set of flags
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* 4) same key if the key field is present.
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*/
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greh2 = (struct gre_base_hdr *)(p->data + off);
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if (greh2->flags != greh->flags ||
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greh2->protocol != greh->protocol) {
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NAPI_GRO_CB(p)->same_flow = 0;
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continue;
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}
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if (greh->flags & GRE_KEY) {
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/* compare keys */
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if (*(__be32 *)(greh2+1) != *(__be32 *)(greh+1)) {
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NAPI_GRO_CB(p)->same_flow = 0;
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continue;
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}
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}
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}
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skb_gro_pull(skb, grehlen);
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/* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/
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skb_gro_postpull_rcsum(skb, greh, grehlen);
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pp = ptype->callbacks.gro_receive(head, skb);
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out_unlock:
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rcu_read_unlock();
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out:
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NAPI_GRO_CB(skb)->flush |= flush;
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return pp;
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}
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static int gre_gro_complete(struct sk_buff *skb, int nhoff)
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{
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struct gre_base_hdr *greh = (struct gre_base_hdr *)(skb->data + nhoff);
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struct packet_offload *ptype;
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unsigned int grehlen = sizeof(*greh);
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int err = -ENOENT;
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__be16 type;
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skb->encapsulation = 1;
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skb_shinfo(skb)->gso_type = SKB_GSO_GRE;
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type = greh->protocol;
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if (greh->flags & GRE_KEY)
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grehlen += GRE_HEADER_SECTION;
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if (greh->flags & GRE_CSUM)
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grehlen += GRE_HEADER_SECTION;
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rcu_read_lock();
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ptype = gro_find_complete_by_type(type);
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if (ptype != NULL)
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err = ptype->callbacks.gro_complete(skb, nhoff + grehlen);
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rcu_read_unlock();
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return err;
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}
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static const struct net_offload gre_offload = {
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.callbacks = {
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.gso_segment = gre_gso_segment,
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.gro_receive = gre_gro_receive,
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.gro_complete = gre_gro_complete,
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},
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};
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static int __init gre_offload_init(void)
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{
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return inet_add_offload(&gre_offload, IPPROTO_GRE);
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}
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device_initcall(gre_offload_init);
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