348 lines
8.3 KiB
C
348 lines
8.3 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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* TCPv4 GSO/GRO support
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*/
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#include <linux/skbuff.h>
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#include <net/tcp.h>
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#include <net/protocol.h>
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static void tcp_gso_tstamp(struct sk_buff *skb, unsigned int ts_seq,
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unsigned int seq, unsigned int mss)
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{
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while (skb) {
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if (before(ts_seq, seq + mss)) {
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skb_shinfo(skb)->tx_flags |= SKBTX_SW_TSTAMP;
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skb_shinfo(skb)->tskey = ts_seq;
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return;
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}
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skb = skb->next;
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seq += mss;
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}
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}
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static struct sk_buff *tcp4_gso_segment(struct sk_buff *skb,
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netdev_features_t features)
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{
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if (!(skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4))
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return ERR_PTR(-EINVAL);
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if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
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return ERR_PTR(-EINVAL);
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if (unlikely(skb->ip_summed != CHECKSUM_PARTIAL)) {
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const struct iphdr *iph = ip_hdr(skb);
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struct tcphdr *th = tcp_hdr(skb);
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/* Set up checksum pseudo header, usually expect stack to
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* have done this already.
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*/
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th->check = 0;
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skb->ip_summed = CHECKSUM_PARTIAL;
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__tcp_v4_send_check(skb, iph->saddr, iph->daddr);
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}
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return tcp_gso_segment(skb, features);
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}
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struct sk_buff *tcp_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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unsigned int sum_truesize = 0;
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struct tcphdr *th;
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unsigned int thlen;
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unsigned int seq;
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__be32 delta;
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unsigned int oldlen;
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unsigned int mss;
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struct sk_buff *gso_skb = skb;
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__sum16 newcheck;
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bool ooo_okay, copy_destructor;
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th = tcp_hdr(skb);
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thlen = th->doff * 4;
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if (thlen < sizeof(*th))
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goto out;
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if (!pskb_may_pull(skb, thlen))
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goto out;
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oldlen = (u16)~skb->len;
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__skb_pull(skb, thlen);
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mss = skb_shinfo(skb)->gso_size;
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if (unlikely(skb->len <= mss))
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goto out;
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if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
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/* Packet is from an untrusted source, reset gso_segs. */
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skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
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segs = NULL;
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goto out;
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}
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copy_destructor = gso_skb->destructor == tcp_wfree;
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ooo_okay = gso_skb->ooo_okay;
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/* All segments but the first should have ooo_okay cleared */
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skb->ooo_okay = 0;
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segs = skb_segment(skb, features);
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if (IS_ERR(segs))
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goto out;
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/* Only first segment might have ooo_okay set */
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segs->ooo_okay = ooo_okay;
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/* GSO partial and frag_list segmentation only requires splitting
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* the frame into an MSS multiple and possibly a remainder, both
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* cases return a GSO skb. So update the mss now.
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*/
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if (skb_is_gso(segs))
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mss *= skb_shinfo(segs)->gso_segs;
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delta = htonl(oldlen + (thlen + mss));
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skb = segs;
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th = tcp_hdr(skb);
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seq = ntohl(th->seq);
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if (unlikely(skb_shinfo(gso_skb)->tx_flags & SKBTX_SW_TSTAMP))
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tcp_gso_tstamp(segs, skb_shinfo(gso_skb)->tskey, seq, mss);
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newcheck = ~csum_fold((__force __wsum)((__force u32)th->check +
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(__force u32)delta));
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while (skb->next) {
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th->fin = th->psh = 0;
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th->check = newcheck;
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if (skb->ip_summed == CHECKSUM_PARTIAL)
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gso_reset_checksum(skb, ~th->check);
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else
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th->check = gso_make_checksum(skb, ~th->check);
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seq += mss;
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if (copy_destructor) {
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skb->destructor = gso_skb->destructor;
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skb->sk = gso_skb->sk;
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sum_truesize += skb->truesize;
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}
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skb = skb->next;
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th = tcp_hdr(skb);
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th->seq = htonl(seq);
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th->cwr = 0;
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}
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/* Following permits TCP Small Queues to work well with GSO :
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* The callback to TCP stack will be called at the time last frag
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* is freed at TX completion, and not right now when gso_skb
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* is freed by GSO engine
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*/
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if (copy_destructor) {
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int delta;
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swap(gso_skb->sk, skb->sk);
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swap(gso_skb->destructor, skb->destructor);
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sum_truesize += skb->truesize;
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delta = sum_truesize - gso_skb->truesize;
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/* In some pathological cases, delta can be negative.
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* We need to either use refcount_add() or refcount_sub_and_test()
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*/
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if (likely(delta >= 0))
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refcount_add(delta, &skb->sk->sk_wmem_alloc);
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else
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WARN_ON_ONCE(refcount_sub_and_test(-delta, &skb->sk->sk_wmem_alloc));
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}
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delta = htonl(oldlen + (skb_tail_pointer(skb) -
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skb_transport_header(skb)) +
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skb->data_len);
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th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
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(__force u32)delta));
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if (skb->ip_summed == CHECKSUM_PARTIAL)
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gso_reset_checksum(skb, ~th->check);
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else
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th->check = gso_make_checksum(skb, ~th->check);
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out:
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return segs;
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}
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struct sk_buff *tcp_gro_receive(struct list_head *head, 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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struct tcphdr *th;
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struct tcphdr *th2;
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unsigned int len;
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unsigned int thlen;
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__be32 flags;
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unsigned int mss = 1;
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unsigned int hlen;
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unsigned int off;
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int flush = 1;
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int i;
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off = skb_gro_offset(skb);
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hlen = off + sizeof(*th);
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th = skb_gro_header_fast(skb, off);
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if (skb_gro_header_hard(skb, hlen)) {
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th = skb_gro_header_slow(skb, hlen, off);
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if (unlikely(!th))
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goto out;
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}
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thlen = th->doff * 4;
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if (thlen < sizeof(*th))
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goto out;
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hlen = off + thlen;
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if (skb_gro_header_hard(skb, hlen)) {
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th = skb_gro_header_slow(skb, hlen, off);
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if (unlikely(!th))
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goto out;
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}
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skb_gro_pull(skb, thlen);
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len = skb_gro_len(skb);
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flags = tcp_flag_word(th);
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list_for_each_entry(p, head, list) {
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if (!NAPI_GRO_CB(p)->same_flow)
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continue;
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th2 = tcp_hdr(p);
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if (*(u32 *)&th->source ^ *(u32 *)&th2->source) {
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NAPI_GRO_CB(p)->same_flow = 0;
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continue;
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}
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goto found;
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}
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p = NULL;
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goto out_check_final;
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found:
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/* Include the IP ID check below from the inner most IP hdr */
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flush = NAPI_GRO_CB(p)->flush;
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flush |= (__force int)(flags & TCP_FLAG_CWR);
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flush |= (__force int)((flags ^ tcp_flag_word(th2)) &
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~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH));
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flush |= (__force int)(th->ack_seq ^ th2->ack_seq);
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for (i = sizeof(*th); i < thlen; i += 4)
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flush |= *(u32 *)((u8 *)th + i) ^
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*(u32 *)((u8 *)th2 + i);
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/* When we receive our second frame we can made a decision on if we
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* continue this flow as an atomic flow with a fixed ID or if we use
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* an incrementing ID.
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*/
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if (NAPI_GRO_CB(p)->flush_id != 1 ||
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NAPI_GRO_CB(p)->count != 1 ||
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!NAPI_GRO_CB(p)->is_atomic)
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flush |= NAPI_GRO_CB(p)->flush_id;
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else
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NAPI_GRO_CB(p)->is_atomic = false;
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mss = skb_shinfo(p)->gso_size;
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flush |= (len - 1) >= mss;
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flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);
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#ifdef CONFIG_TLS_DEVICE
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flush |= p->decrypted ^ skb->decrypted;
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#endif
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if (flush || skb_gro_receive(p, skb)) {
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mss = 1;
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goto out_check_final;
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}
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tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH);
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out_check_final:
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flush = len < mss;
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flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH |
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TCP_FLAG_RST | TCP_FLAG_SYN |
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TCP_FLAG_FIN));
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if (p && (!NAPI_GRO_CB(skb)->same_flow || flush))
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pp = p;
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out:
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NAPI_GRO_CB(skb)->flush |= (flush != 0);
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return pp;
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}
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int tcp_gro_complete(struct sk_buff *skb)
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{
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struct tcphdr *th = tcp_hdr(skb);
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skb->csum_start = (unsigned char *)th - skb->head;
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skb->csum_offset = offsetof(struct tcphdr, check);
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skb->ip_summed = CHECKSUM_PARTIAL;
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skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
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if (th->cwr)
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skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
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return 0;
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}
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EXPORT_SYMBOL(tcp_gro_complete);
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static struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb)
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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 (!NAPI_GRO_CB(skb)->flush &&
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skb_gro_checksum_validate(skb, IPPROTO_TCP,
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inet_gro_compute_pseudo)) {
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NAPI_GRO_CB(skb)->flush = 1;
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return NULL;
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}
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return tcp_gro_receive(head, skb);
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}
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static int tcp4_gro_complete(struct sk_buff *skb, int thoff)
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{
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const struct iphdr *iph = ip_hdr(skb);
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struct tcphdr *th = tcp_hdr(skb);
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th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr,
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iph->daddr, 0);
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skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4;
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if (NAPI_GRO_CB(skb)->is_atomic)
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skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_FIXEDID;
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return tcp_gro_complete(skb);
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}
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static const struct net_offload tcpv4_offload = {
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.callbacks = {
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.gso_segment = tcp4_gso_segment,
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.gro_receive = tcp4_gro_receive,
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.gro_complete = tcp4_gro_complete,
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},
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};
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int __init tcpv4_offload_init(void)
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{
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return inet_add_offload(&tcpv4_offload, IPPROTO_TCP);
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}
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