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) { swap(gso_skb->sk, skb->sk); swap(gso_skb->destructor, skb->destructor); sum_truesize += skb->truesize; atomic_add(sum_truesize - gso_skb->truesize, &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_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; 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_GRE_CSUM | SKB_GSO_IPIP | SKB_GSO_SIT | SKB_GSO_MPLS | SKB_GSO_UDP_TUNNEL | SKB_GSO_UDP_TUNNEL_CSUM | 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); 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)); do { th->fin = th->psh = 0; th->check = newcheck; if (skb->ip_summed != CHECKSUM_PARTIAL) 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; } 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); sum_truesize += skb->truesize; atomic_add(sum_truesize - gso_skb->truesize, &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) th->check = gso_make_checksum(skb, ~th->check); out: return segs; }