1#define KMSG_COMPONENT "IPVS"
2#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
3
4#include <linux/module.h>
5#include <linux/kernel.h>
6
7#include <net/ip_vs.h>
8#include <net/netfilter/nf_conntrack.h>
9#include <linux/netfilter/nf_conntrack_sip.h>
10
11#ifdef CONFIG_IP_VS_DEBUG
12static const char *ip_vs_dbg_callid(char *buf, size_t buf_len,
13				    const char *callid, size_t callid_len,
14				    int *idx)
15{
16	size_t max_len = 64;
17	size_t len = min3(max_len, callid_len, buf_len - *idx - 1);
18	memcpy(buf + *idx, callid, len);
19	buf[*idx+len] = '\0';
20	*idx += len + 1;
21	return buf + *idx - len;
22}
23
24#define IP_VS_DEBUG_CALLID(callid, len)					\
25	ip_vs_dbg_callid(ip_vs_dbg_buf, sizeof(ip_vs_dbg_buf),		\
26			 callid, len, &ip_vs_dbg_idx)
27#endif
28
29static int get_callid(const char *dptr, unsigned int dataoff,
30		      unsigned int datalen,
31		      unsigned int *matchoff, unsigned int *matchlen)
32{
33	/* Find callid */
34	while (1) {
35		int ret = ct_sip_get_header(NULL, dptr, dataoff, datalen,
36					    SIP_HDR_CALL_ID, matchoff,
37					    matchlen);
38		if (ret > 0)
39			break;
40		if (!ret)
41			return -EINVAL;
42		dataoff += *matchoff;
43	}
44
45	/* Too large is useless */
46	if (*matchlen > IP_VS_PEDATA_MAXLEN)
47		return -EINVAL;
48
49	/* SIP headers are always followed by a line terminator */
50	if (*matchoff + *matchlen == datalen)
51		return -EINVAL;
52
53	/* RFC 2543 allows lines to be terminated with CR, LF or CRLF,
54	 * RFC 3261 allows only CRLF, we support both. */
55	if (*(dptr + *matchoff + *matchlen) != '\r' &&
56	    *(dptr + *matchoff + *matchlen) != '\n')
57		return -EINVAL;
58
59	IP_VS_DBG_BUF(9, "SIP callid %s (%d bytes)\n",
60		      IP_VS_DEBUG_CALLID(dptr + *matchoff, *matchlen),
61		      *matchlen);
62	return 0;
63}
64
65static int
66ip_vs_sip_fill_param(struct ip_vs_conn_param *p, struct sk_buff *skb)
67{
68	struct ip_vs_iphdr iph;
69	unsigned int dataoff, datalen, matchoff, matchlen;
70	const char *dptr;
71	int retc;
72
73	ip_vs_fill_iph_skb(p->af, skb, &iph);
74
75	/* Only useful with UDP */
76	if (iph.protocol != IPPROTO_UDP)
77		return -EINVAL;
78	/* todo: IPv6 fragments:
79	 *       I think this only should be done for the first fragment. /HS
80	 */
81	dataoff = iph.len + sizeof(struct udphdr);
82
83	if (dataoff >= skb->len)
84		return -EINVAL;
85	retc = skb_linearize(skb);
86	if (retc < 0)
87		return retc;
88	dptr = skb->data + dataoff;
89	datalen = skb->len - dataoff;
90
91	if (get_callid(dptr, dataoff, datalen, &matchoff, &matchlen))
92		return -EINVAL;
93
94	/* N.B: pe_data is only set on success,
95	 * this allows fallback to the default persistence logic on failure
96	 */
97	p->pe_data = kmemdup(dptr + matchoff, matchlen, GFP_ATOMIC);
98	if (!p->pe_data)
99		return -ENOMEM;
100
101	p->pe_data_len = matchlen;
102
103	return 0;
104}
105
106static bool ip_vs_sip_ct_match(const struct ip_vs_conn_param *p,
107				  struct ip_vs_conn *ct)
108
109{
110	bool ret = false;
111
112	if (ct->af == p->af &&
113	    ip_vs_addr_equal(p->af, p->caddr, &ct->caddr) &&
114	    /* protocol should only be IPPROTO_IP if
115	     * d_addr is a fwmark */
116	    ip_vs_addr_equal(p->protocol == IPPROTO_IP ? AF_UNSPEC : p->af,
117			     p->vaddr, &ct->vaddr) &&
118	    ct->vport == p->vport &&
119	    ct->flags & IP_VS_CONN_F_TEMPLATE &&
120	    ct->protocol == p->protocol &&
121	    ct->pe_data && ct->pe_data_len == p->pe_data_len &&
122	    !memcmp(ct->pe_data, p->pe_data, p->pe_data_len))
123		ret = true;
124
125	IP_VS_DBG_BUF(9, "SIP template match %s %s->%s:%d %s\n",
126		      ip_vs_proto_name(p->protocol),
127		      IP_VS_DEBUG_CALLID(p->pe_data, p->pe_data_len),
128		      IP_VS_DBG_ADDR(p->af, p->vaddr), ntohs(p->vport),
129		      ret ? "hit" : "not hit");
130
131	return ret;
132}
133
134static u32 ip_vs_sip_hashkey_raw(const struct ip_vs_conn_param *p,
135				 u32 initval, bool inverse)
136{
137	return jhash(p->pe_data, p->pe_data_len, initval);
138}
139
140static int ip_vs_sip_show_pe_data(const struct ip_vs_conn *cp, char *buf)
141{
142	memcpy(buf, cp->pe_data, cp->pe_data_len);
143	return cp->pe_data_len;
144}
145
146static struct ip_vs_pe ip_vs_sip_pe =
147{
148	.name =			"sip",
149	.refcnt =		ATOMIC_INIT(0),
150	.module =		THIS_MODULE,
151	.n_list =		LIST_HEAD_INIT(ip_vs_sip_pe.n_list),
152	.fill_param =		ip_vs_sip_fill_param,
153	.ct_match =		ip_vs_sip_ct_match,
154	.hashkey_raw =		ip_vs_sip_hashkey_raw,
155	.show_pe_data =		ip_vs_sip_show_pe_data,
156};
157
158static int __init ip_vs_sip_init(void)
159{
160	return register_ip_vs_pe(&ip_vs_sip_pe);
161}
162
163static void __exit ip_vs_sip_cleanup(void)
164{
165	unregister_ip_vs_pe(&ip_vs_sip_pe);
166	synchronize_rcu();
167}
168
169module_init(ip_vs_sip_init);
170module_exit(ip_vs_sip_cleanup);
171MODULE_LICENSE("GPL");
172