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1/* SPDX-License-Identifier: GPL-2.0 */
2#include <linux/module.h>
3#include <linux/netfilter/nf_tables.h>
4#include <net/netfilter/nf_tables.h>
5#include <net/netfilter/nf_tables_core.h>
6#include <net/netfilter/nf_socket.h>
7#include <net/inet_sock.h>
8#include <net/tcp.h>
9
10struct nft_socket {
11 enum nft_socket_keys key:8;
12 u8 level; /* cgroupv2 level to extract */
13 u8 level_user; /* cgroupv2 level provided by userspace */
14 u8 len;
15 union {
16 u8 dreg;
17 };
18};
19
20static void nft_socket_wildcard(const struct nft_pktinfo *pkt,
21 struct nft_regs *regs, struct sock *sk,
22 u32 *dest)
23{
24 switch (nft_pf(pkt)) {
25 case NFPROTO_IPV4:
26 nft_reg_store8(dest, inet_sk(sk)->inet_rcv_saddr == 0);
27 break;
28#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
29 case NFPROTO_IPV6:
30 nft_reg_store8(dest, ipv6_addr_any(&sk->sk_v6_rcv_saddr));
31 break;
32#endif
33 default:
34 regs->verdict.code = NFT_BREAK;
35 return;
36 }
37}
38
39#ifdef CONFIG_SOCK_CGROUP_DATA
40static noinline bool
41nft_sock_get_eval_cgroupv2(u32 *dest, struct sock *sk, const struct nft_pktinfo *pkt, u32 level)
42{
43 struct cgroup *cgrp;
44 u64 cgid;
45
46 if (!sk_fullsock(sk))
47 return false;
48
49 cgrp = cgroup_ancestor(sock_cgroup_ptr(&sk->sk_cgrp_data), level);
50 if (!cgrp)
51 return false;
52
53 cgid = cgroup_id(cgrp);
54 memcpy(dest, &cgid, sizeof(u64));
55 return true;
56}
57
58/* process context only, uses current->nsproxy. */
59static noinline int nft_socket_cgroup_subtree_level(void)
60{
61 struct cgroup *cgrp = cgroup_get_from_path("/");
62 int level;
63
64 if (IS_ERR(cgrp))
65 return PTR_ERR(cgrp);
66
67 level = cgrp->level;
68
69 cgroup_put(cgrp);
70
71 if (level > 255)
72 return -ERANGE;
73
74 if (unlikely(level < 0)) {
75 DEBUG_NET_WARN_ON_ONCE(1);
76 return -EINVAL;
77 }
78
79 return level;
80}
81#endif
82
83static struct sock *nft_socket_do_lookup(const struct nft_pktinfo *pkt)
84{
85 const struct net_device *indev = nft_in(pkt);
86 const struct sk_buff *skb = pkt->skb;
87 struct sock *sk = NULL;
88
89 if (!indev)
90 return NULL;
91
92 switch (nft_pf(pkt)) {
93 case NFPROTO_IPV4:
94 sk = nf_sk_lookup_slow_v4(nft_net(pkt), skb, indev);
95 break;
96#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
97 case NFPROTO_IPV6:
98 sk = nf_sk_lookup_slow_v6(nft_net(pkt), skb, indev);
99 break;
100#endif
101 default:
102 DEBUG_NET_WARN_ON_ONCE(1);
103 break;
104 }
105
106 return sk;
107}
108
109static void nft_socket_eval(const struct nft_expr *expr,
110 struct nft_regs *regs,
111 const struct nft_pktinfo *pkt)
112{
113 const struct nft_socket *priv = nft_expr_priv(expr);
114 struct sk_buff *skb = pkt->skb;
115 struct sock *sk = skb->sk;
116 u32 *dest = &regs->data[priv->dreg];
117
118 if (sk && !net_eq(nft_net(pkt), sock_net(sk)))
119 sk = NULL;
120
121 if (!sk)
122 sk = nft_socket_do_lookup(pkt);
123
124 if (!sk) {
125 regs->verdict.code = NFT_BREAK;
126 return;
127 }
128
129 switch(priv->key) {
130 case NFT_SOCKET_TRANSPARENT:
131 nft_reg_store8(dest, inet_sk_transparent(sk));
132 break;
133 case NFT_SOCKET_MARK:
134 if (sk_fullsock(sk)) {
135 *dest = READ_ONCE(sk->sk_mark);
136 } else {
137 regs->verdict.code = NFT_BREAK;
138 goto out_put_sk;
139 }
140 break;
141 case NFT_SOCKET_WILDCARD:
142 if (!sk_fullsock(sk)) {
143 regs->verdict.code = NFT_BREAK;
144 goto out_put_sk;
145 }
146 nft_socket_wildcard(pkt, regs, sk, dest);
147 break;
148#ifdef CONFIG_SOCK_CGROUP_DATA
149 case NFT_SOCKET_CGROUPV2:
150 if (!nft_sock_get_eval_cgroupv2(dest, sk, pkt, priv->level)) {
151 regs->verdict.code = NFT_BREAK;
152 goto out_put_sk;
153 }
154 break;
155#endif
156 default:
157 DEBUG_NET_WARN_ON_ONCE(1);
158 regs->verdict.code = NFT_BREAK;
159 }
160
161out_put_sk:
162 if (sk != skb->sk)
163 sock_gen_put(sk);
164}
165
166static const struct nla_policy nft_socket_policy[NFTA_SOCKET_MAX + 1] = {
167 [NFTA_SOCKET_KEY] = NLA_POLICY_MAX(NLA_BE32, 255),
168 [NFTA_SOCKET_DREG] = NLA_POLICY_MAX(NLA_BE32, NFT_REG32_MAX),
169 [NFTA_SOCKET_LEVEL] = NLA_POLICY_MAX(NLA_BE32, 255),
170};
171
172static int nft_socket_init(const struct nft_ctx *ctx,
173 const struct nft_expr *expr,
174 const struct nlattr * const tb[])
175{
176 struct nft_socket *priv = nft_expr_priv(expr);
177 unsigned int len;
178
179 if (!tb[NFTA_SOCKET_DREG] || !tb[NFTA_SOCKET_KEY])
180 return -EINVAL;
181
182 switch(ctx->family) {
183 case NFPROTO_IPV4:
184#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
185 case NFPROTO_IPV6:
186#endif
187 case NFPROTO_INET:
188 break;
189 default:
190 return -EOPNOTSUPP;
191 }
192
193 priv->key = ntohl(nla_get_be32(tb[NFTA_SOCKET_KEY]));
194 switch(priv->key) {
195 case NFT_SOCKET_TRANSPARENT:
196 case NFT_SOCKET_WILDCARD:
197 len = sizeof(u8);
198 break;
199 case NFT_SOCKET_MARK:
200 len = sizeof(u32);
201 break;
202#ifdef CONFIG_SOCK_CGROUP_DATA
203 case NFT_SOCKET_CGROUPV2: {
204 unsigned int level;
205 int err;
206
207 if (!tb[NFTA_SOCKET_LEVEL])
208 return -EINVAL;
209
210 level = ntohl(nla_get_be32(tb[NFTA_SOCKET_LEVEL]));
211 if (level > 255)
212 return -EOPNOTSUPP;
213
214 err = nft_socket_cgroup_subtree_level();
215 if (err < 0)
216 return err;
217
218 priv->level_user = level;
219
220 level += err;
221 /* Implies a giant cgroup tree */
222 if (level > 255)
223 return -EOPNOTSUPP;
224
225 priv->level = level;
226 len = sizeof(u64);
227 break;
228 }
229#endif
230 default:
231 return -EOPNOTSUPP;
232 }
233
234 priv->len = len;
235 return nft_parse_register_store(ctx, tb[NFTA_SOCKET_DREG], &priv->dreg,
236 NULL, NFT_DATA_VALUE, len);
237}
238
239static int nft_socket_dump(struct sk_buff *skb,
240 const struct nft_expr *expr, bool reset)
241{
242 const struct nft_socket *priv = nft_expr_priv(expr);
243
244 if (nla_put_be32(skb, NFTA_SOCKET_KEY, htonl(priv->key)))
245 return -1;
246 if (nft_dump_register(skb, NFTA_SOCKET_DREG, priv->dreg))
247 return -1;
248 if (priv->key == NFT_SOCKET_CGROUPV2 &&
249 nla_put_be32(skb, NFTA_SOCKET_LEVEL, htonl(priv->level_user)))
250 return -1;
251 return 0;
252}
253
254static int nft_socket_validate(const struct nft_ctx *ctx,
255 const struct nft_expr *expr)
256{
257 if (ctx->family != NFPROTO_IPV4 &&
258 ctx->family != NFPROTO_IPV6 &&
259 ctx->family != NFPROTO_INET)
260 return -EOPNOTSUPP;
261
262 return nft_chain_validate_hooks(ctx->chain,
263 (1 << NF_INET_PRE_ROUTING) |
264 (1 << NF_INET_LOCAL_IN) |
265 (1 << NF_INET_LOCAL_OUT));
266}
267
268static struct nft_expr_type nft_socket_type;
269static const struct nft_expr_ops nft_socket_ops = {
270 .type = &nft_socket_type,
271 .size = NFT_EXPR_SIZE(sizeof(struct nft_socket)),
272 .eval = nft_socket_eval,
273 .init = nft_socket_init,
274 .dump = nft_socket_dump,
275 .validate = nft_socket_validate,
276};
277
278static struct nft_expr_type nft_socket_type __read_mostly = {
279 .name = "socket",
280 .ops = &nft_socket_ops,
281 .policy = nft_socket_policy,
282 .maxattr = NFTA_SOCKET_MAX,
283 .owner = THIS_MODULE,
284};
285
286static int __init nft_socket_module_init(void)
287{
288 return nft_register_expr(&nft_socket_type);
289}
290
291static void __exit nft_socket_module_exit(void)
292{
293 nft_unregister_expr(&nft_socket_type);
294}
295
296module_init(nft_socket_module_init);
297module_exit(nft_socket_module_exit);
298
299MODULE_LICENSE("GPL");
300MODULE_AUTHOR("Máté Eckl");
301MODULE_DESCRIPTION("nf_tables socket match module");
302MODULE_ALIAS_NFT_EXPR("socket");