1/*
2 *	xt_ipvs - kernel module to match IPVS connection properties
3 *
4 *	Author: Hannes Eder <heder@google.com>
5 */
6
7#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8
9#include <linux/module.h>
10#include <linux/moduleparam.h>
11#include <linux/spinlock.h>
12#include <linux/skbuff.h>
13#ifdef CONFIG_IP_VS_IPV6
14#include <net/ipv6.h>
15#endif
16#include <linux/ip_vs.h>
17#include <linux/types.h>
18#include <linux/netfilter/x_tables.h>
19#include <linux/netfilter/xt_ipvs.h>
20#include <net/netfilter/nf_conntrack.h>
21
22#include <net/ip_vs.h>
23
24MODULE_AUTHOR("Hannes Eder <heder@google.com>");
25MODULE_DESCRIPTION("Xtables: match IPVS connection properties");
26MODULE_LICENSE("GPL");
27MODULE_ALIAS("ipt_ipvs");
28MODULE_ALIAS("ip6t_ipvs");
29
30/* borrowed from xt_conntrack */
31static bool ipvs_mt_addrcmp(const union nf_inet_addr *kaddr,
32			    const union nf_inet_addr *uaddr,
33			    const union nf_inet_addr *umask,
34			    unsigned int l3proto)
35{
36	if (l3proto == NFPROTO_IPV4)
37		return ((kaddr->ip ^ uaddr->ip) & umask->ip) == 0;
38#ifdef CONFIG_IP_VS_IPV6
39	else if (l3proto == NFPROTO_IPV6)
40		return ipv6_masked_addr_cmp(&kaddr->in6, &umask->in6,
41		       &uaddr->in6) == 0;
42#endif
43	else
44		return false;
45}
46
47static bool
48ipvs_mt(const struct sk_buff *skb, struct xt_action_param *par)
49{
50	const struct xt_ipvs_mtinfo *data = par->matchinfo;
51	/* ipvs_mt_check ensures that family is only NFPROTO_IPV[46]. */
52	const u_int8_t family = par->family;
53	struct ip_vs_iphdr iph;
54	struct ip_vs_protocol *pp;
55	struct ip_vs_conn *cp;
56	bool match = true;
57
58	if (data->bitmask == XT_IPVS_IPVS_PROPERTY) {
59		match = skb->ipvs_property ^
60			!!(data->invert & XT_IPVS_IPVS_PROPERTY);
61		goto out;
62	}
63
64	/* other flags than XT_IPVS_IPVS_PROPERTY are set */
65	if (!skb->ipvs_property) {
66		match = false;
67		goto out;
68	}
69
70	ip_vs_fill_iph_skb(family, skb, &iph);
71
72	if (data->bitmask & XT_IPVS_PROTO)
73		if ((iph.protocol == data->l4proto) ^
74		    !(data->invert & XT_IPVS_PROTO)) {
75			match = false;
76			goto out;
77		}
78
79	pp = ip_vs_proto_get(iph.protocol);
80	if (unlikely(!pp)) {
81		match = false;
82		goto out;
83	}
84
85	/*
86	 * Check if the packet belongs to an existing entry
87	 */
88	cp = pp->conn_out_get(family, skb, &iph, 1 /* inverse */);
89	if (unlikely(cp == NULL)) {
90		match = false;
91		goto out;
92	}
93
94	/*
95	 * We found a connection, i.e. ct != 0, make sure to call
96	 * __ip_vs_conn_put before returning.  In our case jump to out_put_con.
97	 */
98
99	if (data->bitmask & XT_IPVS_VPORT)
100		if ((cp->vport == data->vport) ^
101		    !(data->invert & XT_IPVS_VPORT)) {
102			match = false;
103			goto out_put_cp;
104		}
105
106	if (data->bitmask & XT_IPVS_VPORTCTL)
107		if ((cp->control != NULL &&
108		     cp->control->vport == data->vportctl) ^
109		    !(data->invert & XT_IPVS_VPORTCTL)) {
110			match = false;
111			goto out_put_cp;
112		}
113
114	if (data->bitmask & XT_IPVS_DIR) {
115		enum ip_conntrack_info ctinfo;
116		struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
117
118		if (ct == NULL || nf_ct_is_untracked(ct)) {
119			match = false;
120			goto out_put_cp;
121		}
122
123		if ((ctinfo >= IP_CT_IS_REPLY) ^
124		    !!(data->invert & XT_IPVS_DIR)) {
125			match = false;
126			goto out_put_cp;
127		}
128	}
129
130	if (data->bitmask & XT_IPVS_METHOD)
131		if (((cp->flags & IP_VS_CONN_F_FWD_MASK) == data->fwd_method) ^
132		    !(data->invert & XT_IPVS_METHOD)) {
133			match = false;
134			goto out_put_cp;
135		}
136
137	if (data->bitmask & XT_IPVS_VADDR) {
138		if (ipvs_mt_addrcmp(&cp->vaddr, &data->vaddr,
139				    &data->vmask, family) ^
140		    !(data->invert & XT_IPVS_VADDR)) {
141			match = false;
142			goto out_put_cp;
143		}
144	}
145
146out_put_cp:
147	__ip_vs_conn_put(cp);
148out:
149	pr_debug("match=%d\n", match);
150	return match;
151}
152
153static int ipvs_mt_check(const struct xt_mtchk_param *par)
154{
155	if (par->family != NFPROTO_IPV4
156#ifdef CONFIG_IP_VS_IPV6
157	    && par->family != NFPROTO_IPV6
158#endif
159		) {
160		pr_info("protocol family %u not supported\n", par->family);
161		return -EINVAL;
162	}
163
164	return 0;
165}
166
167static struct xt_match xt_ipvs_mt_reg __read_mostly = {
168	.name       = "ipvs",
169	.revision   = 0,
170	.family     = NFPROTO_UNSPEC,
171	.match      = ipvs_mt,
172	.checkentry = ipvs_mt_check,
173	.matchsize  = XT_ALIGN(sizeof(struct xt_ipvs_mtinfo)),
174	.me         = THIS_MODULE,
175};
176
177static int __init ipvs_mt_init(void)
178{
179	return xt_register_match(&xt_ipvs_mt_reg);
180}
181
182static void __exit ipvs_mt_exit(void)
183{
184	xt_unregister_match(&xt_ipvs_mt_reg);
185}
186
187module_init(ipvs_mt_init);
188module_exit(ipvs_mt_exit);
189