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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_conntrack_zones.h>
22#include <net/netfilter/nf_log.h>
23
24static unsigned int nf_ct_icmp_timeout __read_mostly = 30*HZ;
25
26static bool icmp_pkt_to_tuple(const struct sk_buff *skb, unsigned int dataoff,
27 struct nf_conntrack_tuple *tuple)
28{
29 const struct icmphdr *hp;
30 struct icmphdr _hdr;
31
32 hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
33 if (hp == NULL)
34 return false;
35
36 tuple->dst.u.icmp.type = hp->type;
37 tuple->src.u.icmp.id = hp->un.echo.id;
38 tuple->dst.u.icmp.code = hp->code;
39
40 return true;
41}
42
43
44static const u_int8_t invmap[] = {
45 [ICMP_ECHO] = ICMP_ECHOREPLY + 1,
46 [ICMP_ECHOREPLY] = ICMP_ECHO + 1,
47 [ICMP_TIMESTAMP] = ICMP_TIMESTAMPREPLY + 1,
48 [ICMP_TIMESTAMPREPLY] = ICMP_TIMESTAMP + 1,
49 [ICMP_INFO_REQUEST] = ICMP_INFO_REPLY + 1,
50 [ICMP_INFO_REPLY] = ICMP_INFO_REQUEST + 1,
51 [ICMP_ADDRESS] = ICMP_ADDRESSREPLY + 1,
52 [ICMP_ADDRESSREPLY] = ICMP_ADDRESS + 1
53};
54
55static bool icmp_invert_tuple(struct nf_conntrack_tuple *tuple,
56 const struct nf_conntrack_tuple *orig)
57{
58 if (orig->dst.u.icmp.type >= sizeof(invmap) ||
59 !invmap[orig->dst.u.icmp.type])
60 return false;
61
62 tuple->src.u.icmp.id = orig->src.u.icmp.id;
63 tuple->dst.u.icmp.type = invmap[orig->dst.u.icmp.type] - 1;
64 tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
65 return true;
66}
67
68
69static int icmp_print_tuple(struct seq_file *s,
70 const struct nf_conntrack_tuple *tuple)
71{
72 return seq_printf(s, "type=%u code=%u id=%u ",
73 tuple->dst.u.icmp.type,
74 tuple->dst.u.icmp.code,
75 ntohs(tuple->src.u.icmp.id));
76}
77
78
79static int icmp_packet(struct nf_conn *ct,
80 const struct sk_buff *skb,
81 unsigned int dataoff,
82 enum ip_conntrack_info ctinfo,
83 u_int8_t pf,
84 unsigned int hooknum)
85{
86
87
88
89 nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_icmp_timeout);
90
91 return NF_ACCEPT;
92}
93
94
95static bool icmp_new(struct nf_conn *ct, const struct sk_buff *skb,
96 unsigned int dataoff)
97{
98 static const u_int8_t valid_new[] = {
99 [ICMP_ECHO] = 1,
100 [ICMP_TIMESTAMP] = 1,
101 [ICMP_INFO_REQUEST] = 1,
102 [ICMP_ADDRESS] = 1
103 };
104
105 if (ct->tuplehash[0].tuple.dst.u.icmp.type >= sizeof(valid_new) ||
106 !valid_new[ct->tuplehash[0].tuple.dst.u.icmp.type]) {
107
108 pr_debug("icmp: can't create new conn with type %u\n",
109 ct->tuplehash[0].tuple.dst.u.icmp.type);
110 nf_ct_dump_tuple_ip(&ct->tuplehash[0].tuple);
111 return false;
112 }
113 return true;
114}
115
116
117static int
118icmp_error_message(struct net *net, struct nf_conn *tmpl, struct sk_buff *skb,
119 enum ip_conntrack_info *ctinfo,
120 unsigned int hooknum)
121{
122 struct nf_conntrack_tuple innertuple, origtuple;
123 const struct nf_conntrack_l4proto *innerproto;
124 const struct nf_conntrack_tuple_hash *h;
125 u16 zone = tmpl ? nf_ct_zone(tmpl) : NF_CT_DEFAULT_ZONE;
126
127 NF_CT_ASSERT(skb->nfct == NULL);
128
129
130 if (!nf_ct_get_tuplepr(skb,
131 skb_network_offset(skb) + ip_hdrlen(skb)
132 + sizeof(struct icmphdr),
133 PF_INET, &origtuple)) {
134 pr_debug("icmp_error_message: failed to get tuple\n");
135 return -NF_ACCEPT;
136 }
137
138
139 innerproto = __nf_ct_l4proto_find(PF_INET, origtuple.dst.protonum);
140
141
142
143 if (!nf_ct_invert_tuple(&innertuple, &origtuple,
144 &nf_conntrack_l3proto_ipv4, innerproto)) {
145 pr_debug("icmp_error_message: no match\n");
146 return -NF_ACCEPT;
147 }
148
149 *ctinfo = IP_CT_RELATED;
150
151 h = nf_conntrack_find_get(net, zone, &innertuple);
152 if (!h) {
153 pr_debug("icmp_error_message: no match\n");
154 return -NF_ACCEPT;
155 }
156
157 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
158 *ctinfo += IP_CT_IS_REPLY;
159
160
161 skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
162 skb->nfctinfo = *ctinfo;
163 return -NF_ACCEPT;
164}
165
166
167static int
168icmp_error(struct net *net, struct nf_conn *tmpl,
169 struct sk_buff *skb, unsigned int dataoff,
170 enum ip_conntrack_info *ctinfo, u_int8_t pf, unsigned int hooknum)
171{
172 const struct icmphdr *icmph;
173 struct icmphdr _ih;
174
175
176 icmph = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_ih), &_ih);
177 if (icmph == NULL) {
178 if (LOG_INVALID(net, IPPROTO_ICMP))
179 nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
180 "nf_ct_icmp: short packet ");
181 return -NF_ACCEPT;
182 }
183
184
185 if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
186 nf_ip_checksum(skb, hooknum, dataoff, 0)) {
187 if (LOG_INVALID(net, IPPROTO_ICMP))
188 nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
189 "nf_ct_icmp: bad HW ICMP checksum ");
190 return -NF_ACCEPT;
191 }
192
193
194
195
196
197
198
199 if (icmph->type > NR_ICMP_TYPES) {
200 if (LOG_INVALID(net, IPPROTO_ICMP))
201 nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
202 "nf_ct_icmp: invalid ICMP type ");
203 return -NF_ACCEPT;
204 }
205
206
207 if (icmph->type != ICMP_DEST_UNREACH &&
208 icmph->type != ICMP_SOURCE_QUENCH &&
209 icmph->type != ICMP_TIME_EXCEEDED &&
210 icmph->type != ICMP_PARAMETERPROB &&
211 icmph->type != ICMP_REDIRECT)
212 return NF_ACCEPT;
213
214 return icmp_error_message(net, tmpl, skb, ctinfo, hooknum);
215}
216
217#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
218
219#include <linux/netfilter/nfnetlink.h>
220#include <linux/netfilter/nfnetlink_conntrack.h>
221
222static int icmp_tuple_to_nlattr(struct sk_buff *skb,
223 const struct nf_conntrack_tuple *t)
224{
225 NLA_PUT_BE16(skb, CTA_PROTO_ICMP_ID, t->src.u.icmp.id);
226 NLA_PUT_U8(skb, CTA_PROTO_ICMP_TYPE, t->dst.u.icmp.type);
227 NLA_PUT_U8(skb, CTA_PROTO_ICMP_CODE, t->dst.u.icmp.code);
228
229 return 0;
230
231nla_put_failure:
232 return -1;
233}
234
235static const struct nla_policy icmp_nla_policy[CTA_PROTO_MAX+1] = {
236 [CTA_PROTO_ICMP_TYPE] = { .type = NLA_U8 },
237 [CTA_PROTO_ICMP_CODE] = { .type = NLA_U8 },
238 [CTA_PROTO_ICMP_ID] = { .type = NLA_U16 },
239};
240
241static int icmp_nlattr_to_tuple(struct nlattr *tb[],
242 struct nf_conntrack_tuple *tuple)
243{
244 if (!tb[CTA_PROTO_ICMP_TYPE] ||
245 !tb[CTA_PROTO_ICMP_CODE] ||
246 !tb[CTA_PROTO_ICMP_ID])
247 return -EINVAL;
248
249 tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMP_TYPE]);
250 tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMP_CODE]);
251 tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMP_ID]);
252
253 if (tuple->dst.u.icmp.type >= sizeof(invmap) ||
254 !invmap[tuple->dst.u.icmp.type])
255 return -EINVAL;
256
257 return 0;
258}
259
260static int icmp_nlattr_tuple_size(void)
261{
262 return nla_policy_len(icmp_nla_policy, CTA_PROTO_MAX + 1);
263}
264#endif
265
266#ifdef CONFIG_SYSCTL
267static struct ctl_table_header *icmp_sysctl_header;
268static struct ctl_table icmp_sysctl_table[] = {
269 {
270 .procname = "nf_conntrack_icmp_timeout",
271 .data = &nf_ct_icmp_timeout,
272 .maxlen = sizeof(unsigned int),
273 .mode = 0644,
274 .proc_handler = proc_dointvec_jiffies,
275 },
276 { }
277};
278#ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
279static struct ctl_table icmp_compat_sysctl_table[] = {
280 {
281 .procname = "ip_conntrack_icmp_timeout",
282 .data = &nf_ct_icmp_timeout,
283 .maxlen = sizeof(unsigned int),
284 .mode = 0644,
285 .proc_handler = proc_dointvec_jiffies,
286 },
287 { }
288};
289#endif
290#endif
291
292struct nf_conntrack_l4proto nf_conntrack_l4proto_icmp __read_mostly =
293{
294 .l3proto = PF_INET,
295 .l4proto = IPPROTO_ICMP,
296 .name = "icmp",
297 .pkt_to_tuple = icmp_pkt_to_tuple,
298 .invert_tuple = icmp_invert_tuple,
299 .print_tuple = icmp_print_tuple,
300 .packet = icmp_packet,
301 .new = icmp_new,
302 .error = icmp_error,
303 .destroy = NULL,
304 .me = NULL,
305#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
306 .tuple_to_nlattr = icmp_tuple_to_nlattr,
307 .nlattr_tuple_size = icmp_nlattr_tuple_size,
308 .nlattr_to_tuple = icmp_nlattr_to_tuple,
309 .nla_policy = icmp_nla_policy,
310#endif
311#ifdef CONFIG_SYSCTL
312 .ctl_table_header = &icmp_sysctl_header,
313 .ctl_table = icmp_sysctl_table,
314#ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
315 .ctl_compat_table = icmp_compat_sysctl_table,
316#endif
317#endif
318};
319
