// SPDX-License-Identifier: GPL-2.0-or-later
/*
* IPV4 GSO/GRO offload support
* Linux INET implementation
*
* TCPv4 GSO/GRO support
*/
#include <linux/indirect_call_wrapper.h>
#include <linux/skbuff.h>
#include <net/tcp.h>
#include <net/protocol.h>
static void tcp_gso_tstamp(struct sk_buff *skb, unsigned int ts_seq,
unsigned int seq, unsigned int mss)
{
while (skb) {
if (before(ts_seq, seq + mss)) {
skb_shinfo(skb)->tx_flags |= SKBTX_SW_TSTAMP;
skb_shinfo(skb)->tskey = ts_seq;
return;
}
skb = skb->next;
seq += mss;
}
}
static struct sk_buff *tcp4_gso_segment(struct sk_buff *skb,
netdev_features_t features)
{
if (!(skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4))
return ERR_PTR(-EINVAL);
if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
return ERR_PTR(-EINVAL);
if (unlikely(skb->ip_summed != CHECKSUM_PARTIAL)) {
const struct iphdr *iph = ip_hdr(skb);
struct tcphdr *th = tcp_hdr(skb);
/* Set up checksum pseudo header, usually expect stack to
* have done this already.
*/
th->check = 0;
skb->ip_summed = CHECKSUM_PARTIAL;
__tcp_v4_send_check(skb, iph->saddr, iph->daddr);
}
return tcp_gso_segment(skb, features);
}
struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
netdev_features_t features)
{
struct sk_buff *segs = ERR_PTR(-EINVAL);
unsigned int sum_truesize = 0;
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;
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 = skb_shinfo(skb)->gso_size;
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. */
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;
/* GSO partial and frag_list segmentation only requires splitting
* the frame into an MSS multiple and possibly a remainder, both
* cases return a GSO skb. So update the mss now.
*/
if (skb_is_gso(segs))
mss *= skb_shinfo(segs)->gso_segs;
delta = htonl(oldlen + (thlen + mss));
skb = segs;
th = tcp_hdr(skb);
seq = ntohl(th->seq);
if (unlikely(skb_shinfo(gso_skb)->tx_flags & SKBTX_SW_TSTAMP))
tcp_gso_tstamp(segs, skb_shinfo(gso_skb)->tskey, seq, mss);
newcheck = ~csum_fold((__force __wsum)((__force u32)th->check +
(__force u32)delta));
while (skb->next) {
th->fin = th->psh = 0;
th->check = newcheck;
if (skb->ip_summed == CHECKSUM_PARTIAL)
gso_reset_checksum(skb, ~th->check);
else
th->check = gso_make_checksum(skb, ~th->check);
seq += mss;
if (copy_destructor) {
skb->destructor = gso_skb->destructor;
skb->sk = gso_skb->sk;
sum_truesize += skb->truesize;
}
skb = skb->next;
th = tcp_hdr(skb);
th->seq = htonl(seq);
th->cwr = 0;
}
/* 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) {
int delta;
swap(gso_skb->sk, skb->sk);
swap(gso_skb->destructor, skb->destructor);
sum_truesize += skb->truesize;
delta = sum_truesize - gso_skb->truesize;
/* In some pathological cases, delta can be negative.
* We need to either use refcount_add() or refcount_sub_and_test()
*/
if (likely(delta >= 0))
refcount_add(delta, &skb->sk->sk_wmem_alloc);
else
WARN_ON_ONCE(refcount_sub_and_test(-delta, &skb->sk->sk_wmem_alloc));
}
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)
gso_reset_checksum(skb, ~th->check);
else
th->check = gso_make_checksum(skb, ~th->check);
out:
return segs;
}
struct sk_buff *tcp_gro_receive(struct list_head *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);
list_for_each_entry(p, head, list) {
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;
}
p = NULL;
goto out_check_final;
found:
/* Include the IP ID check below from the inner most IP hdr */
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);
/* When we receive our second frame we can made a decision on if we
* continue this flow as an atomic flow with a fixed ID or if we use
* an incrementing ID.
*/
if (NAPI_GRO_CB(p)->flush_id != 1 ||
NAPI_GRO_CB(p)->count != 1 ||
!NAPI_GRO_CB(p)->is_atomic)
flush |= NAPI_GRO_CB(p)->flush_id;
else
NAPI_GRO_CB(p)->is_atomic = false;
mss = skb_shinfo(p)->gso_size;
flush |= (len - 1) >= mss;
flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);
#ifdef CONFIG_TLS_DEVICE
flush |= p->decrypted ^ skb->decrypted;
#endif
if (flush || skb_gro_receive(p, skb)) {
mss = 1;
goto out_check_final;
}
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 = p;
out:
NAPI_GRO_CB(skb)->flush |= (flush != 0);
return pp;
}
int tcp_gro_complete(struct sk_buff *skb)
{
struct tcphdr *th = tcp_hdr(skb);
skb->csum_start = (unsigned char *)th - 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);
INDIRECT_CALLABLE_SCOPE
struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb)
{
/* Don't bother verifying checksum if we're going to flush anyway. */
if (!NAPI_GRO_CB(skb)->flush &&
skb_gro_checksum_validate(skb, IPPROTO_TCP,
inet_gro_compute_pseudo)) {
NAPI_GRO_CB(skb)->flush = 1;
return NULL;
}
return tcp_gro_receive(head, skb);
}
INDIRECT_CALLABLE_SCOPE int tcp4_gro_complete(struct sk_buff *skb, int thoff)
{
const struct iphdr *iph = ip_hdr(skb);
struct tcphdr *th = tcp_hdr(skb);
th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr,
iph->daddr, 0);
skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4;
if (NAPI_GRO_CB(skb)->is_atomic)
skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_FIXEDID;
return tcp_gro_complete(skb);
}
static const struct net_offload tcpv4_offload = {
.callbacks = {
.gso_segment = tcp4_gso_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);
}
