[mirror_ubuntu-bionic-kernel.git] / net / netfilter / nf_conntrack_seqadj.c

#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 nf_conn *ct,
				      enum ip_conntrack_info ctinfo)
{
	struct tcphdr *tcph = (void *)skb->data + protoff;
	struct nf_conn_seqadj *seqadj = nfct_seqadj(ct);
	unsigned int dir, optoff, optend;

	optoff = protoff + sizeof(struct tcphdr);
	optend = protoff + tcph->doff * 4;

	if (!skb_make_writable(skb, optend))
		return 0;

	tcph = (void *)skb->data + protoff;
	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, 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);
}
Commit	Line	Data
41d73ec0 PM	1	#include <linux/types.h>
	2	#include <linux/netfilter.h>
	3	#include <net/tcp.h>
	4
	5	#include <net/netfilter/nf_conntrack.h>
	6	#include <net/netfilter/nf_conntrack_extend.h>
	7	#include <net/netfilter/nf_conntrack_seqadj.h>
	8
48b1de4c PM	9	int nf_ct_seqadj_init(struct nf_conn *ct, enum ip_conntrack_info ctinfo,
	10	s32 off)
	11	{
	12	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	13	struct nf_conn_seqadj *seqadj;
	14	struct nf_ct_seqadj *this_way;
	15
	16	if (off == 0)
	17	return 0;
	18
	19	set_bit(IPS_SEQ_ADJUST_BIT, &ct->status);
	20
	21	seqadj = nfct_seqadj(ct);
	22	this_way = &seqadj->seq[dir];
	23	this_way->offset_before = off;
	24	this_way->offset_after = off;
	25	return 0;
	26	}
	27	EXPORT_SYMBOL_GPL(nf_ct_seqadj_init);
	28
41d73ec0 PM	29	int nf_ct_seqadj_set(struct nf_conn *ct, enum ip_conntrack_info ctinfo,
	30	__be32 seq, s32 off)
	31	{
	32	struct nf_conn_seqadj *seqadj = nfct_seqadj(ct);
	33	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	34	struct nf_ct_seqadj *this_way;
	35
	36	if (off == 0)
	37	return 0;
	38
db12cf27	39	if (unlikely(!seqadj)) {
f2661adc	40	WARN_ONCE(1, "Missing nfct_seqadj_ext_add() setup call\n");
db12cf27 JDB	41	return 0;
	42	}
	43
41d73ec0 PM	44	set_bit(IPS_SEQ_ADJUST_BIT, &ct->status);
	45
	46	spin_lock_bh(&ct->lock);
	47	this_way = &seqadj->seq[dir];
	48	if (this_way->offset_before == this_way->offset_after \|\|
23dfe136 PO	49	before(this_way->correction_pos, ntohl(seq))) {
23dfe136 PO	50	this_way->correction_pos = ntohl(seq);
41d73ec0 PM	51	this_way->offset_before = this_way->offset_after;
	52	this_way->offset_after += off;
	53	}
	54	spin_unlock_bh(&ct->lock);
	55	return 0;
	56	}
	57	EXPORT_SYMBOL_GPL(nf_ct_seqadj_set);
	58
	59	void nf_ct_tcp_seqadj_set(struct sk_buff *skb,
	60	struct nf_conn *ct, enum ip_conntrack_info ctinfo,
	61	s32 off)
	62	{
	63	const struct tcphdr *th;
	64
	65	if (nf_ct_protonum(ct) != IPPROTO_TCP)
	66	return;
	67
	68	th = (struct tcphdr *)(skb_network_header(skb) + ip_hdrlen(skb));
	69	nf_ct_seqadj_set(ct, ctinfo, th->seq, off);
	70	}
	71	EXPORT_SYMBOL_GPL(nf_ct_tcp_seqadj_set);
	72
	73	/* Adjust one found SACK option including checksum correction */
	74	static void nf_ct_sack_block_adjust(struct sk_buff *skb,
	75	struct tcphdr *tcph,
	76	unsigned int sackoff,
	77	unsigned int sackend,
	78	struct nf_ct_seqadj *seq)
	79	{
	80	while (sackoff < sackend) {
	81	struct tcp_sack_block_wire *sack;
	82	__be32 new_start_seq, new_end_seq;
	83
	84	sack = (void *)skb->data + sackoff;
	85	if (after(ntohl(sack->start_seq) - seq->offset_before,
	86	seq->correction_pos))
	87	new_start_seq = htonl(ntohl(sack->start_seq) -
	88	seq->offset_after);
	89	else
	90	new_start_seq = htonl(ntohl(sack->start_seq) -
	91	seq->offset_before);
	92
	93	if (after(ntohl(sack->end_seq) - seq->offset_before,
	94	seq->correction_pos))
	95	new_end_seq = htonl(ntohl(sack->end_seq) -
	96	seq->offset_after);
	97	else
	98	new_end_seq = htonl(ntohl(sack->end_seq) -
	99	seq->offset_before);
	100
b44b565c G	101	pr_debug("sack_adjust: start_seq: %u->%u, end_seq: %u->%u\n",
	102	ntohl(sack->start_seq), ntohl(new_start_seq),
	103	ntohl(sack->end_seq), ntohl(new_end_seq));
41d73ec0 PM	104
41d73ec0 PM	105	inet_proto_csum_replace4(&tcph->check, skb,
4b048d6d	106	sack->start_seq, new_start_seq, false);
41d73ec0	107	inet_proto_csum_replace4(&tcph->check, skb,
4b048d6d	108	sack->end_seq, new_end_seq, false);
41d73ec0 PM	109	sack->start_seq = new_start_seq;
	110	sack->end_seq = new_end_seq;
	111	sackoff += sizeof(*sack);
	112	}
	113	}
	114
	115	/* TCP SACK sequence number adjustment */
	116	static unsigned int nf_ct_sack_adjust(struct sk_buff *skb,
	117	unsigned int protoff,
41d73ec0 PM	118	struct nf_conn *ct,
	119	enum ip_conntrack_info ctinfo)
	120	{
4d418075	121	struct tcphdr tcph = (void )skb->data + protoff;
41d73ec0	122	struct nf_conn_seqadj *seqadj = nfct_seqadj(ct);
4d418075	123	unsigned int dir, optoff, optend;
41d73ec0 PM	124
	125	optoff = protoff + sizeof(struct tcphdr);
	126	optend = protoff + tcph->doff * 4;
	127
	128	if (!skb_make_writable(skb, optend))
	129	return 0;
	130
4d418075	131	tcph = (void *)skb->data + protoff;
41d73ec0 PM	132	dir = CTINFO2DIR(ctinfo);
	133
	134	while (optoff < optend) {
	135	/* Usually: option, length. */
	136	unsigned char *op = skb->data + optoff;
	137
	138	switch (op[0]) {
	139	case TCPOPT_EOL:
	140	return 1;
	141	case TCPOPT_NOP:
	142	optoff++;
	143	continue;
	144	default:
	145	/* no partial options */
	146	if (optoff + 1 == optend \|\|
	147	optoff + op[1] > optend \|\|
	148	op[1] < 2)
	149	return 0;
	150	if (op[0] == TCPOPT_SACK &&
	151	op[1] >= 2+TCPOLEN_SACK_PERBLOCK &&
	152	((op[1] - 2) % TCPOLEN_SACK_PERBLOCK) == 0)
	153	nf_ct_sack_block_adjust(skb, tcph, optoff + 2,
	154	optoff+op[1],
	155	&seqadj->seq[!dir]);
	156	optoff += op[1];
	157	}
	158	}
	159	return 1;
	160	}
	161
	162	/* TCP sequence number adjustment. Returns 1 on success, 0 on failure */
	163	int nf_ct_seq_adjust(struct sk_buff *skb,
	164	struct nf_conn *ct, enum ip_conntrack_info ctinfo,
	165	unsigned int protoff)
	166	{
	167	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	168	struct tcphdr *tcph;
	169	__be32 newseq, newack;
	170	s32 seqoff, ackoff;
	171	struct nf_conn_seqadj *seqadj = nfct_seqadj(ct);
	172	struct nf_ct_seqadj this_way, other_way;
8d11350f	173	int res = 1;
41d73ec0 PM	174
	175	this_way = &seqadj->seq[dir];
	176	other_way = &seqadj->seq[!dir];
	177
	178	if (!skb_make_writable(skb, protoff + sizeof(*tcph)))
	179	return 0;
	180
	181	tcph = (void *)skb->data + protoff;
	182	spin_lock_bh(&ct->lock);
	183	if (after(ntohl(tcph->seq), this_way->correction_pos))
	184	seqoff = this_way->offset_after;
	185	else
	186	seqoff = this_way->offset_before;
	187
8d11350f GF	188	newseq = htonl(ntohl(tcph->seq) + seqoff);
	189	inet_proto_csum_replace4(&tcph->check, skb, tcph->seq, newseq, false);
	190	pr_debug("Adjusting sequence number from %u->%u\n",
	191	ntohl(tcph->seq), ntohl(newseq));
	192	tcph->seq = newseq;
	193
	194	if (!tcph->ack)
	195	goto out;
	196
41d73ec0 PM	197	if (after(ntohl(tcph->ack_seq) - other_way->offset_before,
	198	other_way->correction_pos))
	199	ackoff = other_way->offset_after;
	200	else
	201	ackoff = other_way->offset_before;
	202
41d73ec0	203	newack = htonl(ntohl(tcph->ack_seq) - ackoff);
4b048d6d TH	204	inet_proto_csum_replace4(&tcph->check, skb, tcph->ack_seq, newack,
4b048d6d TH	205	false);
8d11350f	206	pr_debug("Adjusting ack number from %u->%u, ack from %u->%u\n",
41d73ec0 PM	207	ntohl(tcph->seq), ntohl(newseq), ntohl(tcph->ack_seq),
41d73ec0 PM	208	ntohl(newack));
41d73ec0 PM	209	tcph->ack_seq = newack;
41d73ec0 PM	210
4d418075	211	res = nf_ct_sack_adjust(skb, protoff, ct, ctinfo);
8d11350f	212	out:
41d73ec0 PM	213	spin_unlock_bh(&ct->lock);
	214
	215	return res;
	216	}
	217	EXPORT_SYMBOL_GPL(nf_ct_seq_adjust);
	218
	219	s32 nf_ct_seq_offset(const struct nf_conn *ct,
	220	enum ip_conntrack_dir dir,
	221	u32 seq)
	222	{
	223	struct nf_conn_seqadj *seqadj = nfct_seqadj(ct);
	224	struct nf_ct_seqadj *this_way;
	225
	226	if (!seqadj)
	227	return 0;
	228
	229	this_way = &seqadj->seq[dir];
	230	return after(seq, this_way->correction_pos) ?
	231	this_way->offset_after : this_way->offset_before;
	232	}
	233	EXPORT_SYMBOL_GPL(nf_ct_seq_offset);
	234
23f671a1	235	static const struct nf_ct_ext_type nf_ct_seqadj_extend = {
41d73ec0 PM	236	.len = sizeof(struct nf_conn_seqadj),
	237	.align = __alignof__(struct nf_conn_seqadj),
	238	.id = NF_CT_EXT_SEQADJ,
	239	};
	240
	241	int nf_conntrack_seqadj_init(void)
	242	{
	243	return nf_ct_extend_register(&nf_ct_seqadj_extend);
	244	}
	245
	246	void nf_conntrack_seqadj_fini(void)
	247	{
	248	nf_ct_extend_unregister(&nf_ct_seqadj_extend);
	249	}