net: tcp: move GRO/GSO functions to tcp_offload
Would be good to make things explicit and move those functions to
a new file called tcp_offload.c, thus make this similar to tcpv6_offload.c.
While moving all related functions into tcp_offload.c, we can also
make some of them static, since they are only used there. Also, add
an explicit registration function.
Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c
new file mode 100644
index 0000000..3a7525e
--- /dev/null
+++ b/net/ipv4/tcp_offload.c
@@ -0,0 +1,332 @@
+/*
+ * IPV4 GSO/GRO offload support
+ * Linux INET implementation
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * TCPv4 GSO/GRO support
+ */
+
+#include <linux/skbuff.h>
+#include <net/tcp.h>
+#include <net/protocol.h>
+
+struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
+ netdev_features_t features)
+{
+ struct sk_buff *segs = ERR_PTR(-EINVAL);
+ struct tcphdr *th;
+ unsigned int thlen;
+ unsigned int seq;
+ __be32 delta;
+ unsigned int oldlen;
+ unsigned int mss;
+ struct sk_buff *gso_skb = skb;
+ __sum16 newcheck;
+ bool ooo_okay, copy_destructor;
+
+ if (!pskb_may_pull(skb, sizeof(*th)))
+ goto out;
+
+ th = tcp_hdr(skb);
+ thlen = th->doff * 4;
+ if (thlen < sizeof(*th))
+ goto out;
+
+ if (!pskb_may_pull(skb, thlen))
+ goto out;
+
+ oldlen = (u16)~skb->len;
+ __skb_pull(skb, thlen);
+
+ mss = tcp_skb_mss(skb);
+ if (unlikely(skb->len <= mss))
+ goto out;
+
+ if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
+ /* Packet is from an untrusted source, reset gso_segs. */
+ int type = skb_shinfo(skb)->gso_type;
+
+ if (unlikely(type &
+ ~(SKB_GSO_TCPV4 |
+ SKB_GSO_DODGY |
+ SKB_GSO_TCP_ECN |
+ SKB_GSO_TCPV6 |
+ SKB_GSO_GRE |
+ SKB_GSO_MPLS |
+ SKB_GSO_UDP_TUNNEL |
+ 0) ||
+ !(type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))))
+ goto out;
+
+ skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
+
+ segs = NULL;
+ goto out;
+ }
+
+ copy_destructor = gso_skb->destructor == tcp_wfree;
+ ooo_okay = gso_skb->ooo_okay;
+ /* All segments but the first should have ooo_okay cleared */
+ skb->ooo_okay = 0;
+
+ segs = skb_segment(skb, features);
+ if (IS_ERR(segs))
+ goto out;
+
+ /* Only first segment might have ooo_okay set */
+ segs->ooo_okay = ooo_okay;
+
+ delta = htonl(oldlen + (thlen + mss));
+
+ skb = segs;
+ th = tcp_hdr(skb);
+ seq = ntohl(th->seq);
+
+ newcheck = ~csum_fold((__force __wsum)((__force u32)th->check +
+ (__force u32)delta));
+
+ do {
+ th->fin = th->psh = 0;
+ th->check = newcheck;
+
+ if (skb->ip_summed != CHECKSUM_PARTIAL)
+ th->check =
+ csum_fold(csum_partial(skb_transport_header(skb),
+ thlen, skb->csum));
+
+ seq += mss;
+ if (copy_destructor) {
+ skb->destructor = gso_skb->destructor;
+ skb->sk = gso_skb->sk;
+ /* {tcp|sock}_wfree() use exact truesize accounting :
+ * sum(skb->truesize) MUST be exactly be gso_skb->truesize
+ * So we account mss bytes of 'true size' for each segment.
+ * The last segment will contain the remaining.
+ */
+ skb->truesize = mss;
+ gso_skb->truesize -= mss;
+ }
+ skb = skb->next;
+ th = tcp_hdr(skb);
+
+ th->seq = htonl(seq);
+ th->cwr = 0;
+ } while (skb->next);
+
+ /* Following permits TCP Small Queues to work well with GSO :
+ * The callback to TCP stack will be called at the time last frag
+ * is freed at TX completion, and not right now when gso_skb
+ * is freed by GSO engine
+ */
+ if (copy_destructor) {
+ swap(gso_skb->sk, skb->sk);
+ swap(gso_skb->destructor, skb->destructor);
+ swap(gso_skb->truesize, skb->truesize);
+ }
+
+ delta = htonl(oldlen + (skb_tail_pointer(skb) -
+ skb_transport_header(skb)) +
+ skb->data_len);
+ th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
+ (__force u32)delta));
+ if (skb->ip_summed != CHECKSUM_PARTIAL)
+ th->check = csum_fold(csum_partial(skb_transport_header(skb),
+ thlen, skb->csum));
+out:
+ return segs;
+}
+EXPORT_SYMBOL(tcp_tso_segment);
+
+struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb)
+{
+ struct sk_buff **pp = NULL;
+ struct sk_buff *p;
+ struct tcphdr *th;
+ struct tcphdr *th2;
+ unsigned int len;
+ unsigned int thlen;
+ __be32 flags;
+ unsigned int mss = 1;
+ unsigned int hlen;
+ unsigned int off;
+ int flush = 1;
+ int i;
+
+ off = skb_gro_offset(skb);
+ hlen = off + sizeof(*th);
+ th = skb_gro_header_fast(skb, off);
+ if (skb_gro_header_hard(skb, hlen)) {
+ th = skb_gro_header_slow(skb, hlen, off);
+ if (unlikely(!th))
+ goto out;
+ }
+
+ thlen = th->doff * 4;
+ if (thlen < sizeof(*th))
+ goto out;
+
+ hlen = off + thlen;
+ if (skb_gro_header_hard(skb, hlen)) {
+ th = skb_gro_header_slow(skb, hlen, off);
+ if (unlikely(!th))
+ goto out;
+ }
+
+ skb_gro_pull(skb, thlen);
+
+ len = skb_gro_len(skb);
+ flags = tcp_flag_word(th);
+
+ for (; (p = *head); head = &p->next) {
+ if (!NAPI_GRO_CB(p)->same_flow)
+ continue;
+
+ th2 = tcp_hdr(p);
+
+ if (*(u32 *)&th->source ^ *(u32 *)&th2->source) {
+ NAPI_GRO_CB(p)->same_flow = 0;
+ continue;
+ }
+
+ goto found;
+ }
+
+ goto out_check_final;
+
+found:
+ flush = NAPI_GRO_CB(p)->flush;
+ flush |= (__force int)(flags & TCP_FLAG_CWR);
+ flush |= (__force int)((flags ^ tcp_flag_word(th2)) &
+ ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH));
+ flush |= (__force int)(th->ack_seq ^ th2->ack_seq);
+ for (i = sizeof(*th); i < thlen; i += 4)
+ flush |= *(u32 *)((u8 *)th + i) ^
+ *(u32 *)((u8 *)th2 + i);
+
+ mss = tcp_skb_mss(p);
+
+ flush |= (len - 1) >= mss;
+ flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);
+
+ if (flush || skb_gro_receive(head, skb)) {
+ mss = 1;
+ goto out_check_final;
+ }
+
+ p = *head;
+ th2 = tcp_hdr(p);
+ tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH);
+
+out_check_final:
+ flush = len < mss;
+ flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH |
+ TCP_FLAG_RST | TCP_FLAG_SYN |
+ TCP_FLAG_FIN));
+
+ if (p && (!NAPI_GRO_CB(skb)->same_flow || flush))
+ pp = head;
+
+out:
+ NAPI_GRO_CB(skb)->flush |= flush;
+
+ return pp;
+}
+EXPORT_SYMBOL(tcp_gro_receive);
+
+int tcp_gro_complete(struct sk_buff *skb)
+{
+ struct tcphdr *th = tcp_hdr(skb);
+
+ skb->csum_start = skb_transport_header(skb) - skb->head;
+ skb->csum_offset = offsetof(struct tcphdr, check);
+ skb->ip_summed = CHECKSUM_PARTIAL;
+
+ skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
+
+ if (th->cwr)
+ skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
+
+ return 0;
+}
+EXPORT_SYMBOL(tcp_gro_complete);
+
+static int tcp_v4_gso_send_check(struct sk_buff *skb)
+{
+ const struct iphdr *iph;
+ struct tcphdr *th;
+
+ if (!pskb_may_pull(skb, sizeof(*th)))
+ return -EINVAL;
+
+ iph = ip_hdr(skb);
+ th = tcp_hdr(skb);
+
+ th->check = 0;
+ skb->ip_summed = CHECKSUM_PARTIAL;
+ __tcp_v4_send_check(skb, iph->saddr, iph->daddr);
+ return 0;
+}
+
+static struct sk_buff **tcp4_gro_receive(struct sk_buff **head, struct sk_buff *skb)
+{
+ const struct iphdr *iph = skb_gro_network_header(skb);
+ __wsum wsum;
+ __sum16 sum;
+
+ switch (skb->ip_summed) {
+ case CHECKSUM_COMPLETE:
+ if (!tcp_v4_check(skb_gro_len(skb), iph->saddr, iph->daddr,
+ skb->csum)) {
+ skb->ip_summed = CHECKSUM_UNNECESSARY;
+ break;
+ }
+flush:
+ NAPI_GRO_CB(skb)->flush = 1;
+ return NULL;
+
+ case CHECKSUM_NONE:
+ wsum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
+ skb_gro_len(skb), IPPROTO_TCP, 0);
+ sum = csum_fold(skb_checksum(skb,
+ skb_gro_offset(skb),
+ skb_gro_len(skb),
+ wsum));
+ if (sum)
+ goto flush;
+
+ skb->ip_summed = CHECKSUM_UNNECESSARY;
+ break;
+ }
+
+ return tcp_gro_receive(head, skb);
+}
+
+static int tcp4_gro_complete(struct sk_buff *skb)
+{
+ const struct iphdr *iph = ip_hdr(skb);
+ struct tcphdr *th = tcp_hdr(skb);
+
+ th->check = ~tcp_v4_check(skb->len - skb_transport_offset(skb),
+ iph->saddr, iph->daddr, 0);
+ skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
+
+ return tcp_gro_complete(skb);
+}
+
+static const struct net_offload tcpv4_offload = {
+ .callbacks = {
+ .gso_send_check = tcp_v4_gso_send_check,
+ .gso_segment = tcp_tso_segment,
+ .gro_receive = tcp4_gro_receive,
+ .gro_complete = tcp4_gro_complete,
+ },
+};
+
+int __init tcpv4_offload_init(void)
+{
+ return inet_add_offload(&tcpv4_offload, IPPROTO_TCP);
+}