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path: root/net/netfilter/nf_conntrack_seqadj.c
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Diffstat (limited to 'net/netfilter/nf_conntrack_seqadj.c')
-rw-r--r--net/netfilter/nf_conntrack_seqadj.c218
1 files changed, 218 insertions, 0 deletions
diff --git a/net/netfilter/nf_conntrack_seqadj.c b/net/netfilter/nf_conntrack_seqadj.c
new file mode 100644
index 000000000000..483eb9ce3216
--- /dev/null
+++ b/net/netfilter/nf_conntrack_seqadj.c
@@ -0,0 +1,218 @@
+#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_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;
+
+ 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, seq)) {
+ this_way->correction_pos = 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: %d->%d, end_seq: %d->%d\n",
+ ntohl(sack->start_seq), new_start_seq,
+ ntohl(sack->end_seq), new_end_seq);
+
+ inet_proto_csum_replace4(&tcph->check, skb,
+ sack->start_seq, new_start_seq, 0);
+ inet_proto_csum_replace4(&tcph->check, skb,
+ sack->end_seq, new_end_seq, 0);
+ 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;
+
+ 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;
+
+ 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;
+
+ newseq = htonl(ntohl(tcph->seq) + seqoff);
+ newack = htonl(ntohl(tcph->ack_seq) - ackoff);
+
+ inet_proto_csum_replace4(&tcph->check, skb, tcph->seq, newseq, 0);
+ inet_proto_csum_replace4(&tcph->check, skb, tcph->ack_seq, newack, 0);
+
+ pr_debug("Adjusting sequence number from %u->%u, ack from %u->%u\n",
+ ntohl(tcph->seq), ntohl(newseq), ntohl(tcph->ack_seq),
+ ntohl(newack));
+
+ tcph->seq = newseq;
+ tcph->ack_seq = newack;
+
+ res = nf_ct_sack_adjust(skb, protoff, tcph, ct, ctinfo);
+ 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 struct nf_ct_ext_type nf_ct_seqadj_extend __read_mostly = {
+ .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);
+}