| #include <linux/types.h> |
| #include <linux/netfilter.h> |
| #include <net/tcp.h> |
| |
| #include <net/netfilter/nf_conntrack.h> |
| #include <net/netfilter/nf_conntrack_extend.h> |
| #include <net/netfilter/nf_conntrack_seqadj.h> |
| |
| int nf_ct_seqadj_init(struct nf_conn *ct, enum ip_conntrack_info ctinfo, |
| s32 off) |
| { |
| enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); |
| struct nf_conn_seqadj *seqadj; |
| struct nf_ct_seqadj *this_way; |
| |
| if (off == 0) |
| return 0; |
| |
| set_bit(IPS_SEQ_ADJUST_BIT, &ct->status); |
| |
| seqadj = nfct_seqadj(ct); |
| this_way = &seqadj->seq[dir]; |
| this_way->offset_before = off; |
| this_way->offset_after = off; |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(nf_ct_seqadj_init); |
| |
| int nf_ct_seqadj_set(struct nf_conn *ct, enum ip_conntrack_info ctinfo, |
| __be32 seq, s32 off) |
| { |
| struct nf_conn_seqadj *seqadj = nfct_seqadj(ct); |
| enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); |
| struct nf_ct_seqadj *this_way; |
| |
| if (off == 0) |
| return 0; |
| |
| if (unlikely(!seqadj)) { |
| WARN_ONCE(1, "Missing nfct_seqadj_ext_add() setup call\n"); |
| return 0; |
| } |
| |
| set_bit(IPS_SEQ_ADJUST_BIT, &ct->status); |
| |
| spin_lock_bh(&ct->lock); |
| this_way = &seqadj->seq[dir]; |
| if (this_way->offset_before == this_way->offset_after || |
| before(this_way->correction_pos, ntohl(seq))) { |
| this_way->correction_pos = ntohl(seq); |
| this_way->offset_before = this_way->offset_after; |
| this_way->offset_after += off; |
| } |
| spin_unlock_bh(&ct->lock); |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(nf_ct_seqadj_set); |
| |
| void nf_ct_tcp_seqadj_set(struct sk_buff *skb, |
| struct nf_conn *ct, enum ip_conntrack_info ctinfo, |
| s32 off) |
| { |
| const struct tcphdr *th; |
| |
| if (nf_ct_protonum(ct) != IPPROTO_TCP) |
| return; |
| |
| th = (struct tcphdr *)(skb_network_header(skb) + ip_hdrlen(skb)); |
| nf_ct_seqadj_set(ct, ctinfo, th->seq, off); |
| } |
| EXPORT_SYMBOL_GPL(nf_ct_tcp_seqadj_set); |
| |
| /* Adjust one found SACK option including checksum correction */ |
| static void nf_ct_sack_block_adjust(struct sk_buff *skb, |
| struct tcphdr *tcph, |
| unsigned int sackoff, |
| unsigned int sackend, |
| struct nf_ct_seqadj *seq) |
| { |
| while (sackoff < sackend) { |
| struct tcp_sack_block_wire *sack; |
| __be32 new_start_seq, new_end_seq; |
| |
| sack = (void *)skb->data + sackoff; |
| if (after(ntohl(sack->start_seq) - seq->offset_before, |
| seq->correction_pos)) |
| new_start_seq = htonl(ntohl(sack->start_seq) - |
| seq->offset_after); |
| else |
| new_start_seq = htonl(ntohl(sack->start_seq) - |
| seq->offset_before); |
| |
| if (after(ntohl(sack->end_seq) - seq->offset_before, |
| seq->correction_pos)) |
| new_end_seq = htonl(ntohl(sack->end_seq) - |
| seq->offset_after); |
| else |
| new_end_seq = htonl(ntohl(sack->end_seq) - |
| seq->offset_before); |
| |
| pr_debug("sack_adjust: start_seq: %u->%u, end_seq: %u->%u\n", |
| ntohl(sack->start_seq), ntohl(new_start_seq), |
| ntohl(sack->end_seq), ntohl(new_end_seq)); |
| |
| inet_proto_csum_replace4(&tcph->check, skb, |
| sack->start_seq, new_start_seq, false); |
| inet_proto_csum_replace4(&tcph->check, skb, |
| sack->end_seq, new_end_seq, false); |
| sack->start_seq = new_start_seq; |
| sack->end_seq = new_end_seq; |
| sackoff += sizeof(*sack); |
| } |
| } |
| |
| /* TCP SACK sequence number adjustment */ |
| static unsigned int nf_ct_sack_adjust(struct sk_buff *skb, |
| unsigned int protoff, |
| struct tcphdr *tcph, |
| struct nf_conn *ct, |
| enum ip_conntrack_info ctinfo) |
| { |
| unsigned int dir, optoff, optend; |
| struct nf_conn_seqadj *seqadj = nfct_seqadj(ct); |
| |
| optoff = protoff + sizeof(struct tcphdr); |
| optend = protoff + tcph->doff * 4; |
| |
| if (!skb_make_writable(skb, optend)) |
| return 0; |
| |
| dir = CTINFO2DIR(ctinfo); |
| |
| while (optoff < optend) { |
| /* Usually: option, length. */ |
| unsigned char *op = skb->data + optoff; |
| |
| switch (op[0]) { |
| case TCPOPT_EOL: |
| return 1; |
| case TCPOPT_NOP: |
| optoff++; |
| continue; |
| default: |
| /* no partial options */ |
| if (optoff + 1 == optend || |
| optoff + op[1] > optend || |
| op[1] < 2) |
| return 0; |
| if (op[0] == TCPOPT_SACK && |
| op[1] >= 2+TCPOLEN_SACK_PERBLOCK && |
| ((op[1] - 2) % TCPOLEN_SACK_PERBLOCK) == 0) |
| nf_ct_sack_block_adjust(skb, tcph, optoff + 2, |
| optoff+op[1], |
| &seqadj->seq[!dir]); |
| optoff += op[1]; |
| } |
| } |
| return 1; |
| } |
| |
| /* TCP sequence number adjustment. Returns 1 on success, 0 on failure */ |
| int nf_ct_seq_adjust(struct sk_buff *skb, |
| struct nf_conn *ct, enum ip_conntrack_info ctinfo, |
| unsigned int protoff) |
| { |
| enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); |
| struct tcphdr *tcph; |
| __be32 newseq, newack; |
| s32 seqoff, ackoff; |
| struct nf_conn_seqadj *seqadj = nfct_seqadj(ct); |
| struct nf_ct_seqadj *this_way, *other_way; |
| int res = 1; |
| |
| this_way = &seqadj->seq[dir]; |
| other_way = &seqadj->seq[!dir]; |
| |
| if (!skb_make_writable(skb, protoff + sizeof(*tcph))) |
| return 0; |
| |
| tcph = (void *)skb->data + protoff; |
| spin_lock_bh(&ct->lock); |
| if (after(ntohl(tcph->seq), this_way->correction_pos)) |
| seqoff = this_way->offset_after; |
| else |
| seqoff = this_way->offset_before; |
| |
| newseq = htonl(ntohl(tcph->seq) + seqoff); |
| inet_proto_csum_replace4(&tcph->check, skb, tcph->seq, newseq, false); |
| pr_debug("Adjusting sequence number from %u->%u\n", |
| ntohl(tcph->seq), ntohl(newseq)); |
| tcph->seq = newseq; |
| |
| if (!tcph->ack) |
| goto out; |
| |
| if (after(ntohl(tcph->ack_seq) - other_way->offset_before, |
| other_way->correction_pos)) |
| ackoff = other_way->offset_after; |
| else |
| ackoff = other_way->offset_before; |
| |
| newack = htonl(ntohl(tcph->ack_seq) - ackoff); |
| inet_proto_csum_replace4(&tcph->check, skb, tcph->ack_seq, newack, |
| false); |
| pr_debug("Adjusting ack number from %u->%u, ack from %u->%u\n", |
| ntohl(tcph->seq), ntohl(newseq), ntohl(tcph->ack_seq), |
| ntohl(newack)); |
| tcph->ack_seq = newack; |
| |
| res = nf_ct_sack_adjust(skb, protoff, tcph, ct, ctinfo); |
| out: |
| spin_unlock_bh(&ct->lock); |
| |
| return res; |
| } |
| EXPORT_SYMBOL_GPL(nf_ct_seq_adjust); |
| |
| s32 nf_ct_seq_offset(const struct nf_conn *ct, |
| enum ip_conntrack_dir dir, |
| u32 seq) |
| { |
| struct nf_conn_seqadj *seqadj = nfct_seqadj(ct); |
| struct nf_ct_seqadj *this_way; |
| |
| if (!seqadj) |
| return 0; |
| |
| this_way = &seqadj->seq[dir]; |
| return after(seq, this_way->correction_pos) ? |
| this_way->offset_after : this_way->offset_before; |
| } |
| EXPORT_SYMBOL_GPL(nf_ct_seq_offset); |
| |
| static const struct nf_ct_ext_type nf_ct_seqadj_extend = { |
| .len = sizeof(struct nf_conn_seqadj), |
| .align = __alignof__(struct nf_conn_seqadj), |
| .id = NF_CT_EXT_SEQADJ, |
| }; |
| |
| int nf_conntrack_seqadj_init(void) |
| { |
| return nf_ct_extend_register(&nf_ct_seqadj_extend); |
| } |
| |
| void nf_conntrack_seqadj_fini(void) |
| { |
| nf_ct_extend_unregister(&nf_ct_seqadj_extend); |
| } |