1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/kernel.h>
3 #include <linux/init.h>
4 #include <linux/module.h>
5 #include <linux/skbuff.h>
6 #include <linux/netfilter.h>
7 #include <linux/mutex.h>
8 #include <net/sock.h>
9 
10 #include "nf_internals.h"
11 
12 /* Sockopts only registered and called from user context, so
13    net locking would be overkill.  Also, [gs]etsockopt calls may
14    sleep. */
15 static DEFINE_MUTEX(nf_sockopt_mutex);
16 static LIST_HEAD(nf_sockopts);
17 
18 /* Do exclusive ranges overlap? */
overlap(int min1,int max1,int min2,int max2)19 static inline int overlap(int min1, int max1, int min2, int max2)
20 {
21 	return max1 > min2 && min1 < max2;
22 }
23 
24 /* Functions to register sockopt ranges (exclusive). */
nf_register_sockopt(struct nf_sockopt_ops * reg)25 int nf_register_sockopt(struct nf_sockopt_ops *reg)
26 {
27 	struct nf_sockopt_ops *ops;
28 	int ret = 0;
29 
30 	mutex_lock(&nf_sockopt_mutex);
31 	list_for_each_entry(ops, &nf_sockopts, list) {
32 		if (ops->pf == reg->pf
33 		    && (overlap(ops->set_optmin, ops->set_optmax,
34 				reg->set_optmin, reg->set_optmax)
35 			|| overlap(ops->get_optmin, ops->get_optmax,
36 				   reg->get_optmin, reg->get_optmax))) {
37 			pr_debug("nf_sock overlap: %u-%u/%u-%u v %u-%u/%u-%u\n",
38 				ops->set_optmin, ops->set_optmax,
39 				ops->get_optmin, ops->get_optmax,
40 				reg->set_optmin, reg->set_optmax,
41 				reg->get_optmin, reg->get_optmax);
42 			ret = -EBUSY;
43 			goto out;
44 		}
45 	}
46 
47 	list_add(&reg->list, &nf_sockopts);
48 out:
49 	mutex_unlock(&nf_sockopt_mutex);
50 	return ret;
51 }
52 EXPORT_SYMBOL(nf_register_sockopt);
53 
nf_unregister_sockopt(struct nf_sockopt_ops * reg)54 void nf_unregister_sockopt(struct nf_sockopt_ops *reg)
55 {
56 	mutex_lock(&nf_sockopt_mutex);
57 	list_del(&reg->list);
58 	mutex_unlock(&nf_sockopt_mutex);
59 }
60 EXPORT_SYMBOL(nf_unregister_sockopt);
61 
nf_sockopt_find(struct sock * sk,u_int8_t pf,int val,int get)62 static struct nf_sockopt_ops *nf_sockopt_find(struct sock *sk, u_int8_t pf,
63 		int val, int get)
64 {
65 	struct nf_sockopt_ops *ops;
66 
67 	mutex_lock(&nf_sockopt_mutex);
68 	list_for_each_entry(ops, &nf_sockopts, list) {
69 		if (ops->pf == pf) {
70 			if (!try_module_get(ops->owner))
71 				goto out_nosup;
72 
73 			if (get) {
74 				if (val >= ops->get_optmin &&
75 						val < ops->get_optmax)
76 					goto out;
77 			} else {
78 				if (val >= ops->set_optmin &&
79 						val < ops->set_optmax)
80 					goto out;
81 			}
82 			module_put(ops->owner);
83 		}
84 	}
85 out_nosup:
86 	ops = ERR_PTR(-ENOPROTOOPT);
87 out:
88 	mutex_unlock(&nf_sockopt_mutex);
89 	return ops;
90 }
91 
nf_setsockopt(struct sock * sk,u_int8_t pf,int val,sockptr_t opt,unsigned int len)92 int nf_setsockopt(struct sock *sk, u_int8_t pf, int val, sockptr_t opt,
93 		  unsigned int len)
94 {
95 	struct nf_sockopt_ops *ops;
96 	int ret;
97 
98 	ops = nf_sockopt_find(sk, pf, val, 0);
99 	if (IS_ERR(ops))
100 		return PTR_ERR(ops);
101 	ret = ops->set(sk, val, opt, len);
102 	module_put(ops->owner);
103 	return ret;
104 }
105 EXPORT_SYMBOL(nf_setsockopt);
106 
nf_getsockopt(struct sock * sk,u_int8_t pf,int val,char __user * opt,int * len)107 int nf_getsockopt(struct sock *sk, u_int8_t pf, int val, char __user *opt,
108 		  int *len)
109 {
110 	struct nf_sockopt_ops *ops;
111 	int ret;
112 
113 	ops = nf_sockopt_find(sk, pf, val, 1);
114 	if (IS_ERR(ops))
115 		return PTR_ERR(ops);
116 	ret = ops->get(sk, val, opt, len);
117 	module_put(ops->owner);
118 	return ret;
119 }
120 EXPORT_SYMBOL(nf_getsockopt);
121