1 // SPDX-License-Identifier: GPL-2.0-only
2 #define KMSG_COMPONENT "IPVS"
3 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
4 
5 #include <linux/module.h>
6 #include <linux/kernel.h>
7 
8 #include <net/ip_vs.h>
9 #include <net/netfilter/nf_conntrack.h>
10 #include <linux/netfilter/nf_conntrack_sip.h>
11 
12 #ifdef CONFIG_IP_VS_DEBUG
ip_vs_dbg_callid(char * buf,size_t buf_len,const char * callid,size_t callid_len,int * idx)13 static const char *ip_vs_dbg_callid(char *buf, size_t buf_len,
14 				    const char *callid, size_t callid_len,
15 				    int *idx)
16 {
17 	size_t max_len = 64;
18 	size_t len = min3(max_len, callid_len, buf_len - *idx - 1);
19 	memcpy(buf + *idx, callid, len);
20 	buf[*idx+len] = '\0';
21 	*idx += len + 1;
22 	return buf + *idx - len;
23 }
24 
25 #define IP_VS_DEBUG_CALLID(callid, len)					\
26 	ip_vs_dbg_callid(ip_vs_dbg_buf, sizeof(ip_vs_dbg_buf),		\
27 			 callid, len, &ip_vs_dbg_idx)
28 #endif
29 
get_callid(const char * dptr,unsigned int dataoff,unsigned int datalen,unsigned int * matchoff,unsigned int * matchlen)30 static int get_callid(const char *dptr, unsigned int dataoff,
31 		      unsigned int datalen,
32 		      unsigned int *matchoff, unsigned int *matchlen)
33 {
34 	/* Find callid */
35 	while (1) {
36 		int ret = ct_sip_get_header(NULL, dptr, dataoff, datalen,
37 					    SIP_HDR_CALL_ID, matchoff,
38 					    matchlen);
39 		if (ret > 0)
40 			break;
41 		if (!ret)
42 			return -EINVAL;
43 		dataoff += *matchoff;
44 	}
45 
46 	/* Too large is useless */
47 	if (*matchlen > IP_VS_PEDATA_MAXLEN)
48 		return -EINVAL;
49 
50 	/* SIP headers are always followed by a line terminator */
51 	if (*matchoff + *matchlen == datalen)
52 		return -EINVAL;
53 
54 	/* RFC 2543 allows lines to be terminated with CR, LF or CRLF,
55 	 * RFC 3261 allows only CRLF, we support both. */
56 	if (*(dptr + *matchoff + *matchlen) != '\r' &&
57 	    *(dptr + *matchoff + *matchlen) != '\n')
58 		return -EINVAL;
59 
60 	IP_VS_DBG_BUF(9, "SIP callid %s (%d bytes)\n",
61 		      IP_VS_DEBUG_CALLID(dptr + *matchoff, *matchlen),
62 		      *matchlen);
63 	return 0;
64 }
65 
66 static int
ip_vs_sip_fill_param(struct ip_vs_conn_param * p,struct sk_buff * skb)67 ip_vs_sip_fill_param(struct ip_vs_conn_param *p, struct sk_buff *skb)
68 {
69 	struct ip_vs_iphdr iph;
70 	unsigned int dataoff, datalen, matchoff, matchlen;
71 	const char *dptr;
72 	int retc;
73 
74 	retc = ip_vs_fill_iph_skb(p->af, skb, false, &iph);
75 
76 	/* Only useful with UDP */
77 	if (!retc || iph.protocol != IPPROTO_UDP)
78 		return -EINVAL;
79 	/* todo: IPv6 fragments:
80 	 *       I think this only should be done for the first fragment. /HS
81 	 */
82 	dataoff = iph.len + sizeof(struct udphdr);
83 
84 	if (dataoff >= skb->len)
85 		return -EINVAL;
86 	retc = skb_linearize(skb);
87 	if (retc < 0)
88 		return retc;
89 	dptr = skb->data + dataoff;
90 	datalen = skb->len - dataoff;
91 
92 	if (get_callid(dptr, 0, datalen, &matchoff, &matchlen))
93 		return -EINVAL;
94 
95 	/* N.B: pe_data is only set on success,
96 	 * this allows fallback to the default persistence logic on failure
97 	 */
98 	p->pe_data = kmemdup(dptr + matchoff, matchlen, GFP_ATOMIC);
99 	if (!p->pe_data)
100 		return -ENOMEM;
101 
102 	p->pe_data_len = matchlen;
103 
104 	return 0;
105 }
106 
ip_vs_sip_ct_match(const struct ip_vs_conn_param * p,struct ip_vs_conn * ct)107 static bool ip_vs_sip_ct_match(const struct ip_vs_conn_param *p,
108 				  struct ip_vs_conn *ct)
109 
110 {
111 	bool ret = false;
112 
113 	if (ct->af == p->af &&
114 	    ip_vs_addr_equal(p->af, p->caddr, &ct->caddr) &&
115 	    /* protocol should only be IPPROTO_IP if
116 	     * d_addr is a fwmark */
117 	    ip_vs_addr_equal(p->protocol == IPPROTO_IP ? AF_UNSPEC : p->af,
118 			     p->vaddr, &ct->vaddr) &&
119 	    ct->vport == p->vport &&
120 	    ct->flags & IP_VS_CONN_F_TEMPLATE &&
121 	    ct->protocol == p->protocol &&
122 	    ct->pe_data && ct->pe_data_len == p->pe_data_len &&
123 	    !memcmp(ct->pe_data, p->pe_data, p->pe_data_len))
124 		ret = true;
125 
126 	IP_VS_DBG_BUF(9, "SIP template match %s %s->%s:%d %s\n",
127 		      ip_vs_proto_name(p->protocol),
128 		      IP_VS_DEBUG_CALLID(p->pe_data, p->pe_data_len),
129 		      IP_VS_DBG_ADDR(p->af, p->vaddr), ntohs(p->vport),
130 		      ret ? "hit" : "not hit");
131 
132 	return ret;
133 }
134 
ip_vs_sip_hashkey_raw(const struct ip_vs_conn_param * p,u32 initval,bool inverse)135 static u32 ip_vs_sip_hashkey_raw(const struct ip_vs_conn_param *p,
136 				 u32 initval, bool inverse)
137 {
138 	return jhash(p->pe_data, p->pe_data_len, initval);
139 }
140 
ip_vs_sip_show_pe_data(const struct ip_vs_conn * cp,char * buf)141 static int ip_vs_sip_show_pe_data(const struct ip_vs_conn *cp, char *buf)
142 {
143 	memcpy(buf, cp->pe_data, cp->pe_data_len);
144 	return cp->pe_data_len;
145 }
146 
147 static struct ip_vs_conn *
ip_vs_sip_conn_out(struct ip_vs_service * svc,struct ip_vs_dest * dest,struct sk_buff * skb,const struct ip_vs_iphdr * iph,__be16 dport,__be16 cport)148 ip_vs_sip_conn_out(struct ip_vs_service *svc,
149 		   struct ip_vs_dest *dest,
150 		   struct sk_buff *skb,
151 		   const struct ip_vs_iphdr *iph,
152 		   __be16 dport,
153 		   __be16 cport)
154 {
155 	if (likely(iph->protocol == IPPROTO_UDP))
156 		return ip_vs_new_conn_out(svc, dest, skb, iph, dport, cport);
157 	/* currently no need to handle other than UDP */
158 	return NULL;
159 }
160 
161 static struct ip_vs_pe ip_vs_sip_pe =
162 {
163 	.name =			"sip",
164 	.refcnt =		ATOMIC_INIT(0),
165 	.module =		THIS_MODULE,
166 	.n_list =		LIST_HEAD_INIT(ip_vs_sip_pe.n_list),
167 	.fill_param =		ip_vs_sip_fill_param,
168 	.ct_match =		ip_vs_sip_ct_match,
169 	.hashkey_raw =		ip_vs_sip_hashkey_raw,
170 	.show_pe_data =		ip_vs_sip_show_pe_data,
171 	.conn_out =		ip_vs_sip_conn_out,
172 };
173 
ip_vs_sip_init(void)174 static int __init ip_vs_sip_init(void)
175 {
176 	return register_ip_vs_pe(&ip_vs_sip_pe);
177 }
178 
ip_vs_sip_cleanup(void)179 static void __exit ip_vs_sip_cleanup(void)
180 {
181 	unregister_ip_vs_pe(&ip_vs_sip_pe);
182 	synchronize_rcu();
183 }
184 
185 module_init(ip_vs_sip_init);
186 module_exit(ip_vs_sip_cleanup);
187 MODULE_LICENSE("GPL");
188