1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 *	xt_ipvs - kernel module to match IPVS connection properties
4 *
5 *	Author: Hannes Eder <heder@google.com>
6 */
7
8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10#include <linux/module.h>
11#include <linux/moduleparam.h>
12#include <linux/spinlock.h>
13#include <linux/skbuff.h>
14#ifdef CONFIG_IP_VS_IPV6
15#include <net/ipv6.h>
16#endif
17#include <linux/ip_vs.h>
18#include <linux/types.h>
19#include <linux/netfilter/x_tables.h>
20#include <linux/netfilter/xt_ipvs.h>
21#include <net/netfilter/nf_conntrack.h>
22
23#include <net/ip_vs.h>
24
25MODULE_AUTHOR("Hannes Eder <heder@google.com>");
26MODULE_DESCRIPTION("Xtables: match IPVS connection properties");
27MODULE_LICENSE("GPL");
28MODULE_ALIAS("ipt_ipvs");
29MODULE_ALIAS("ip6t_ipvs");
30
31/* borrowed from xt_conntrack */
32static bool ipvs_mt_addrcmp(const union nf_inet_addr *kaddr,
33			    const union nf_inet_addr *uaddr,
34			    const union nf_inet_addr *umask,
35			    unsigned int l3proto)
36{
37	if (l3proto == NFPROTO_IPV4)
38		return ((kaddr->ip ^ uaddr->ip) & umask->ip) == 0;
39#ifdef CONFIG_IP_VS_IPV6
40	else if (l3proto == NFPROTO_IPV6)
41		return ipv6_masked_addr_cmp(&kaddr->in6, &umask->in6,
42		       &uaddr->in6) == 0;
43#endif
44	else
45		return false;
46}
47
48static bool
49ipvs_mt(const struct sk_buff *skb, struct xt_action_param *par)
50{
51	const struct xt_ipvs_mtinfo *data = par->matchinfo;
52	struct netns_ipvs *ipvs = net_ipvs(xt_net(par));
53	/* ipvs_mt_check ensures that family is only NFPROTO_IPV[46]. */
54	const u_int8_t family = xt_family(par);
55	struct ip_vs_iphdr iph;
56	struct ip_vs_protocol *pp;
57	struct ip_vs_conn *cp;
58	bool match = true;
59
60	if (data->bitmask == XT_IPVS_IPVS_PROPERTY) {
61		match = skb->ipvs_property ^
62			!!(data->invert & XT_IPVS_IPVS_PROPERTY);
63		goto out;
64	}
65
66	/* other flags than XT_IPVS_IPVS_PROPERTY are set */
67	if (!skb->ipvs_property) {
68		match = false;
69		goto out;
70	}
71
72	ip_vs_fill_iph_skb(family, skb, true, &iph);
73
74	if (data->bitmask & XT_IPVS_PROTO)
75		if ((iph.protocol == data->l4proto) ^
76		    !(data->invert & XT_IPVS_PROTO)) {
77			match = false;
78			goto out;
79		}
80
81	pp = ip_vs_proto_get(iph.protocol);
82	if (unlikely(!pp)) {
83		match = false;
84		goto out;
85	}
86
87	/*
88	 * Check if the packet belongs to an existing entry
89	 */
90	cp = pp->conn_out_get(ipvs, family, skb, &iph);
91	if (unlikely(cp == NULL)) {
92		match = false;
93		goto out;
94	}
95
96	/*
97	 * We found a connection, i.e. ct != 0, make sure to call
98	 * __ip_vs_conn_put before returning.  In our case jump to out_put_con.
99	 */
100
101	if (data->bitmask & XT_IPVS_VPORT)
102		if ((cp->vport == data->vport) ^
103		    !(data->invert & XT_IPVS_VPORT)) {
104			match = false;
105			goto out_put_cp;
106		}
107
108	if (data->bitmask & XT_IPVS_VPORTCTL)
109		if ((cp->control != NULL &&
110		     cp->control->vport == data->vportctl) ^
111		    !(data->invert & XT_IPVS_VPORTCTL)) {
112			match = false;
113			goto out_put_cp;
114		}
115
116	if (data->bitmask & XT_IPVS_DIR) {
117		enum ip_conntrack_info ctinfo;
118		struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
119
120		if (ct == NULL) {
121			match = false;
122			goto out_put_cp;
123		}
124
125		if ((ctinfo >= IP_CT_IS_REPLY) ^
126		    !!(data->invert & XT_IPVS_DIR)) {
127			match = false;
128			goto out_put_cp;
129		}
130	}
131
132	if (data->bitmask & XT_IPVS_METHOD)
133		if (((cp->flags & IP_VS_CONN_F_FWD_MASK) == data->fwd_method) ^
134		    !(data->invert & XT_IPVS_METHOD)) {
135			match = false;
136			goto out_put_cp;
137		}
138
139	if (data->bitmask & XT_IPVS_VADDR) {
140		if (ipvs_mt_addrcmp(&cp->vaddr, &data->vaddr,
141				    &data->vmask, family) ^
142		    !(data->invert & XT_IPVS_VADDR)) {
143			match = false;
144			goto out_put_cp;
145		}
146	}
147
148out_put_cp:
149	__ip_vs_conn_put(cp);
150out:
151	pr_debug("match=%d\n", match);
152	return match;
153}
154
155static int ipvs_mt_check(const struct xt_mtchk_param *par)
156{
157	if (par->family != NFPROTO_IPV4
158#ifdef CONFIG_IP_VS_IPV6
159	    && par->family != NFPROTO_IPV6
160#endif
161		) {
162		pr_info_ratelimited("protocol family %u not supported\n",
163				    par->family);
164		return -EINVAL;
165	}
166
167	return 0;
168}
169
170static struct xt_match xt_ipvs_mt_reg __read_mostly = {
171	.name       = "ipvs",
172	.revision   = 0,
173	.family     = NFPROTO_UNSPEC,
174	.match      = ipvs_mt,
175	.checkentry = ipvs_mt_check,
176	.matchsize  = XT_ALIGN(sizeof(struct xt_ipvs_mtinfo)),
177	.me         = THIS_MODULE,
178};
179
180static int __init ipvs_mt_init(void)
181{
182	return xt_register_match(&xt_ipvs_mt_reg);
183}
184
185static void __exit ipvs_mt_exit(void)
186{
187	xt_unregister_match(&xt_ipvs_mt_reg);
188}
189
190module_init(ipvs_mt_init);
191module_exit(ipvs_mt_exit);
192