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9#include <linux/types.h>
10#include <linux/timer.h>
11#include <linux/netfilter.h>
12#include <linux/in.h>
13#include <linux/icmp.h>
14#include <linux/seq_file.h>
15#include <net/ip.h>
16#include <net/checksum.h>
17#include <linux/netfilter_ipv4.h>
18#include <net/netfilter/nf_conntrack_tuple.h>
19#include <net/netfilter/nf_conntrack_l4proto.h>
20#include <net/netfilter/nf_conntrack_core.h>
21#include <net/netfilter/nf_log.h>
22
23static unsigned int nf_ct_icmp_timeout __read_mostly = 30*HZ;
24
25static bool icmp_pkt_to_tuple(const struct sk_buff *skb, unsigned int dataoff,
26 struct nf_conntrack_tuple *tuple)
27{
28 const struct icmphdr *hp;
29 struct icmphdr _hdr;
30
31 hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
32 if (hp == NULL)
33 return false;
34
35 tuple->dst.u.icmp.type = hp->type;
36 tuple->src.u.icmp.id = hp->un.echo.id;
37 tuple->dst.u.icmp.code = hp->code;
38
39 return true;
40}
41
42
43static const u_int8_t invmap[] = {
44 [ICMP_ECHO] = ICMP_ECHOREPLY + 1,
45 [ICMP_ECHOREPLY] = ICMP_ECHO + 1,
46 [ICMP_TIMESTAMP] = ICMP_TIMESTAMPREPLY + 1,
47 [ICMP_TIMESTAMPREPLY] = ICMP_TIMESTAMP + 1,
48 [ICMP_INFO_REQUEST] = ICMP_INFO_REPLY + 1,
49 [ICMP_INFO_REPLY] = ICMP_INFO_REQUEST + 1,
50 [ICMP_ADDRESS] = ICMP_ADDRESSREPLY + 1,
51 [ICMP_ADDRESSREPLY] = ICMP_ADDRESS + 1
52};
53
54static bool icmp_invert_tuple(struct nf_conntrack_tuple *tuple,
55 const struct nf_conntrack_tuple *orig)
56{
57 if (orig->dst.u.icmp.type >= sizeof(invmap)
58 || !invmap[orig->dst.u.icmp.type])
59 return false;
60
61 tuple->src.u.icmp.id = orig->src.u.icmp.id;
62 tuple->dst.u.icmp.type = invmap[orig->dst.u.icmp.type] - 1;
63 tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
64 return true;
65}
66
67
68static int icmp_print_tuple(struct seq_file *s,
69 const struct nf_conntrack_tuple *tuple)
70{
71 return seq_printf(s, "type=%u code=%u id=%u ",
72 tuple->dst.u.icmp.type,
73 tuple->dst.u.icmp.code,
74 ntohs(tuple->src.u.icmp.id));
75}
76
77
78static int icmp_packet(struct nf_conn *ct,
79 const struct sk_buff *skb,
80 unsigned int dataoff,
81 enum ip_conntrack_info ctinfo,
82 u_int8_t pf,
83 unsigned int hooknum)
84{
85
86
87
88 nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_icmp_timeout);
89
90 return NF_ACCEPT;
91}
92
93
94static bool icmp_new(struct nf_conn *ct, const struct sk_buff *skb,
95 unsigned int dataoff)
96{
97 static const u_int8_t valid_new[] = {
98 [ICMP_ECHO] = 1,
99 [ICMP_TIMESTAMP] = 1,
100 [ICMP_INFO_REQUEST] = 1,
101 [ICMP_ADDRESS] = 1
102 };
103
104 if (ct->tuplehash[0].tuple.dst.u.icmp.type >= sizeof(valid_new)
105 || !valid_new[ct->tuplehash[0].tuple.dst.u.icmp.type]) {
106
107 pr_debug("icmp: can't create new conn with type %u\n",
108 ct->tuplehash[0].tuple.dst.u.icmp.type);
109 nf_ct_dump_tuple_ip(&ct->tuplehash[0].tuple);
110 return false;
111 }
112 return true;
113}
114
115
116static int
117icmp_error_message(struct net *net, struct sk_buff *skb,
118 enum ip_conntrack_info *ctinfo,
119 unsigned int hooknum)
120{
121 struct nf_conntrack_tuple innertuple, origtuple;
122 const struct nf_conntrack_l4proto *innerproto;
123 const struct nf_conntrack_tuple_hash *h;
124
125 NF_CT_ASSERT(skb->nfct == NULL);
126
127
128 if (!nf_ct_get_tuplepr(skb,
129 skb_network_offset(skb) + ip_hdrlen(skb)
130 + sizeof(struct icmphdr),
131 PF_INET, &origtuple)) {
132 pr_debug("icmp_error_message: failed to get tuple\n");
133 return -NF_ACCEPT;
134 }
135
136
137 innerproto = __nf_ct_l4proto_find(PF_INET, origtuple.dst.protonum);
138
139
140
141 if (!nf_ct_invert_tuple(&innertuple, &origtuple,
142 &nf_conntrack_l3proto_ipv4, innerproto)) {
143 pr_debug("icmp_error_message: no match\n");
144 return -NF_ACCEPT;
145 }
146
147 *ctinfo = IP_CT_RELATED;
148
149 h = nf_conntrack_find_get(net, &innertuple);
150 if (!h) {
151 pr_debug("icmp_error_message: no match\n");
152 return -NF_ACCEPT;
153 }
154
155 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
156 *ctinfo += IP_CT_IS_REPLY;
157
158
159 skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
160 skb->nfctinfo = *ctinfo;
161 return -NF_ACCEPT;
162}
163
164
165static int
166icmp_error(struct net *net, struct sk_buff *skb, unsigned int dataoff,
167 enum ip_conntrack_info *ctinfo, u_int8_t pf, unsigned int hooknum)
168{
169 const struct icmphdr *icmph;
170 struct icmphdr _ih;
171
172
173 icmph = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_ih), &_ih);
174 if (icmph == NULL) {
175 if (LOG_INVALID(net, IPPROTO_ICMP))
176 nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
177 "nf_ct_icmp: short packet ");
178 return -NF_ACCEPT;
179 }
180
181
182 if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
183 nf_ip_checksum(skb, hooknum, dataoff, 0)) {
184 if (LOG_INVALID(net, IPPROTO_ICMP))
185 nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
186 "nf_ct_icmp: bad HW ICMP checksum ");
187 return -NF_ACCEPT;
188 }
189
190
191
192
193
194
195
196 if (icmph->type > NR_ICMP_TYPES) {
197 if (LOG_INVALID(net, IPPROTO_ICMP))
198 nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
199 "nf_ct_icmp: invalid ICMP type ");
200 return -NF_ACCEPT;
201 }
202
203
204 if (icmph->type != ICMP_DEST_UNREACH
205 && icmph->type != ICMP_SOURCE_QUENCH
206 && icmph->type != ICMP_TIME_EXCEEDED
207 && icmph->type != ICMP_PARAMETERPROB
208 && icmph->type != ICMP_REDIRECT)
209 return NF_ACCEPT;
210
211 return icmp_error_message(net, skb, ctinfo, hooknum);
212}
213
214#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
215
216#include <linux/netfilter/nfnetlink.h>
217#include <linux/netfilter/nfnetlink_conntrack.h>
218
219static int icmp_tuple_to_nlattr(struct sk_buff *skb,
220 const struct nf_conntrack_tuple *t)
221{
222 NLA_PUT_BE16(skb, CTA_PROTO_ICMP_ID, t->src.u.icmp.id);
223 NLA_PUT_U8(skb, CTA_PROTO_ICMP_TYPE, t->dst.u.icmp.type);
224 NLA_PUT_U8(skb, CTA_PROTO_ICMP_CODE, t->dst.u.icmp.code);
225
226 return 0;
227
228nla_put_failure:
229 return -1;
230}
231
232static const struct nla_policy icmp_nla_policy[CTA_PROTO_MAX+1] = {
233 [CTA_PROTO_ICMP_TYPE] = { .type = NLA_U8 },
234 [CTA_PROTO_ICMP_CODE] = { .type = NLA_U8 },
235 [CTA_PROTO_ICMP_ID] = { .type = NLA_U16 },
236};
237
238static int icmp_nlattr_to_tuple(struct nlattr *tb[],
239 struct nf_conntrack_tuple *tuple)
240{
241 if (!tb[CTA_PROTO_ICMP_TYPE]
242 || !tb[CTA_PROTO_ICMP_CODE]
243 || !tb[CTA_PROTO_ICMP_ID])
244 return -EINVAL;
245
246 tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMP_TYPE]);
247 tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMP_CODE]);
248 tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMP_ID]);
249
250 if (tuple->dst.u.icmp.type >= sizeof(invmap)
251 || !invmap[tuple->dst.u.icmp.type])
252 return -EINVAL;
253
254 return 0;
255}
256
257static int icmp_nlattr_tuple_size(void)
258{
259 return nla_policy_len(icmp_nla_policy, CTA_PROTO_MAX + 1);
260}
261#endif
262
263#ifdef CONFIG_SYSCTL
264static struct ctl_table_header *icmp_sysctl_header;
265static struct ctl_table icmp_sysctl_table[] = {
266 {
267 .procname = "nf_conntrack_icmp_timeout",
268 .data = &nf_ct_icmp_timeout,
269 .maxlen = sizeof(unsigned int),
270 .mode = 0644,
271 .proc_handler = proc_dointvec_jiffies,
272 },
273 {
274 .ctl_name = 0
275 }
276};
277#ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
278static struct ctl_table icmp_compat_sysctl_table[] = {
279 {
280 .procname = "ip_conntrack_icmp_timeout",
281 .data = &nf_ct_icmp_timeout,
282 .maxlen = sizeof(unsigned int),
283 .mode = 0644,
284 .proc_handler = proc_dointvec_jiffies,
285 },
286 {
287 .ctl_name = 0
288 }
289};
290#endif
291#endif
292
293struct nf_conntrack_l4proto nf_conntrack_l4proto_icmp __read_mostly =
294{
295 .l3proto = PF_INET,
296 .l4proto = IPPROTO_ICMP,
297 .name = "icmp",
298 .pkt_to_tuple = icmp_pkt_to_tuple,
299 .invert_tuple = icmp_invert_tuple,
300 .print_tuple = icmp_print_tuple,
301 .packet = icmp_packet,
302 .new = icmp_new,
303 .error = icmp_error,
304 .destroy = NULL,
305 .me = NULL,
306#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
307 .tuple_to_nlattr = icmp_tuple_to_nlattr,
308 .nlattr_tuple_size = icmp_nlattr_tuple_size,
309 .nlattr_to_tuple = icmp_nlattr_to_tuple,
310 .nla_policy = icmp_nla_policy,
311#endif
312#ifdef CONFIG_SYSCTL
313 .ctl_table_header = &icmp_sysctl_header,
314 .ctl_table = icmp_sysctl_table,
315#ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
316 .ctl_compat_table = icmp_compat_sysctl_table,
317#endif
318#endif
319};
320
