xref: /openbmc/linux/net/netfilter/xt_ipvs.c (revision 09c434b8)
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 
25 MODULE_AUTHOR("Hannes Eder <heder@google.com>");
26 MODULE_DESCRIPTION("Xtables: match IPVS connection properties");
27 MODULE_LICENSE("GPL");
28 MODULE_ALIAS("ipt_ipvs");
29 MODULE_ALIAS("ip6t_ipvs");
30 
31 /* borrowed from xt_conntrack */
ipvs_mt_addrcmp(const union nf_inet_addr * kaddr,const union nf_inet_addr * uaddr,const union nf_inet_addr * umask,unsigned int l3proto)32 static 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 
48 static bool
ipvs_mt(const struct sk_buff * skb,struct xt_action_param * par)49 ipvs_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 
148 out_put_cp:
149 	__ip_vs_conn_put(cp);
150 out:
151 	pr_debug("match=%d\n", match);
152 	return match;
153 }
154 
ipvs_mt_check(const struct xt_mtchk_param * par)155 static 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 
170 static 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 
ipvs_mt_init(void)180 static int __init ipvs_mt_init(void)
181 {
182 	return xt_register_match(&xt_ipvs_mt_reg);
183 }
184 
ipvs_mt_exit(void)185 static void __exit ipvs_mt_exit(void)
186 {
187 	xt_unregister_match(&xt_ipvs_mt_reg);
188 }
189 
190 module_init(ipvs_mt_init);
191 module_exit(ipvs_mt_exit);
192