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1/*
2 * IPv6 library code, needed by static components when full IPv6 support is
3 * not configured or static.
4 */
5#include <net/ipv6.h>
6
7/*
8 * find out if nexthdr is a well-known extension header or a protocol
9 */
10
11int ipv6_ext_hdr(u8 nexthdr)
12{
13 /*
14 * find out if nexthdr is an extension header or a protocol
15 */
16 return (nexthdr == NEXTHDR_HOP) ||
17 (nexthdr == NEXTHDR_ROUTING) ||
18 (nexthdr == NEXTHDR_FRAGMENT) ||
19 (nexthdr == NEXTHDR_AUTH) ||
20 (nexthdr == NEXTHDR_NONE) ||
21 (nexthdr == NEXTHDR_DEST);
22}
23
24/*
25 * Skip any extension headers. This is used by the ICMP module.
26 *
27 * Note that strictly speaking this conflicts with RFC 2460 4.0:
28 * ...The contents and semantics of each extension header determine whether
29 * or not to proceed to the next header. Therefore, extension headers must
30 * be processed strictly in the order they appear in the packet; a
31 * receiver must not, for example, scan through a packet looking for a
32 * particular kind of extension header and process that header prior to
33 * processing all preceding ones.
34 *
35 * We do exactly this. This is a protocol bug. We can't decide after a
36 * seeing an unknown discard-with-error flavour TLV option if it's a
37 * ICMP error message or not (errors should never be send in reply to
38 * ICMP error messages).
39 *
40 * But I see no other way to do this. This might need to be reexamined
41 * when Linux implements ESP (and maybe AUTH) headers.
42 * --AK
43 *
44 * This function parses (probably truncated) exthdr set "hdr".
45 * "nexthdrp" initially points to some place,
46 * where type of the first header can be found.
47 *
48 * It skips all well-known exthdrs, and returns pointer to the start
49 * of unparsable area i.e. the first header with unknown type.
50 * If it is not NULL *nexthdr is updated by type/protocol of this header.
51 *
52 * NOTES: - if packet terminated with NEXTHDR_NONE it returns NULL.
53 * - it may return pointer pointing beyond end of packet,
54 * if the last recognized header is truncated in the middle.
55 * - if packet is truncated, so that all parsed headers are skipped,
56 * it returns NULL.
57 * - First fragment header is skipped, not-first ones
58 * are considered as unparsable.
59 * - ESP is unparsable for now and considered like
60 * normal payload protocol.
61 * - Note also special handling of AUTH header. Thanks to IPsec wizards.
62 *
63 * --ANK (980726)
64 */
65
66int ipv6_skip_exthdr(const struct sk_buff *skb, int start, u8 *nexthdrp)
67{
68 u8 nexthdr = *nexthdrp;
69
70 while (ipv6_ext_hdr(nexthdr)) {
71 struct ipv6_opt_hdr _hdr, *hp;
72 int hdrlen;
73
74 if (nexthdr == NEXTHDR_NONE)
75 return -1;
76 hp = skb_header_pointer(skb, start, sizeof(_hdr), &_hdr);
77 if (hp == NULL)
78 return -1;
79 if (nexthdr == NEXTHDR_FRAGMENT) {
80 __be16 _frag_off, *fp;
81 fp = skb_header_pointer(skb,
82 start+offsetof(struct frag_hdr,
83 frag_off),
84 sizeof(_frag_off),
85 &_frag_off);
86 if (fp == NULL)
87 return -1;
88
89 if (ntohs(*fp) & ~0x7)
90 break;
91 hdrlen = 8;
92 } else if (nexthdr == NEXTHDR_AUTH)
93 hdrlen = (hp->hdrlen+2)<<2;
94 else
95 hdrlen = ipv6_optlen(hp);
96
97 nexthdr = hp->nexthdr;
98 start += hdrlen;
99 }
100
101 *nexthdrp = nexthdr;
102 return start;
103}
104
105EXPORT_SYMBOL(ipv6_ext_hdr);
106EXPORT_SYMBOL(ipv6_skip_exthdr);
1/*
2 * IPv6 library code, needed by static components when full IPv6 support is
3 * not configured or static.
4 */
5#include <linux/export.h>
6#include <net/ipv6.h>
7
8/*
9 * find out if nexthdr is a well-known extension header or a protocol
10 */
11
12bool ipv6_ext_hdr(u8 nexthdr)
13{
14 /*
15 * find out if nexthdr is an extension header or a protocol
16 */
17 return (nexthdr == NEXTHDR_HOP) ||
18 (nexthdr == NEXTHDR_ROUTING) ||
19 (nexthdr == NEXTHDR_FRAGMENT) ||
20 (nexthdr == NEXTHDR_AUTH) ||
21 (nexthdr == NEXTHDR_NONE) ||
22 (nexthdr == NEXTHDR_DEST);
23}
24EXPORT_SYMBOL(ipv6_ext_hdr);
25
26/*
27 * Skip any extension headers. This is used by the ICMP module.
28 *
29 * Note that strictly speaking this conflicts with RFC 2460 4.0:
30 * ...The contents and semantics of each extension header determine whether
31 * or not to proceed to the next header. Therefore, extension headers must
32 * be processed strictly in the order they appear in the packet; a
33 * receiver must not, for example, scan through a packet looking for a
34 * particular kind of extension header and process that header prior to
35 * processing all preceding ones.
36 *
37 * We do exactly this. This is a protocol bug. We can't decide after a
38 * seeing an unknown discard-with-error flavour TLV option if it's a
39 * ICMP error message or not (errors should never be send in reply to
40 * ICMP error messages).
41 *
42 * But I see no other way to do this. This might need to be reexamined
43 * when Linux implements ESP (and maybe AUTH) headers.
44 * --AK
45 *
46 * This function parses (probably truncated) exthdr set "hdr".
47 * "nexthdrp" initially points to some place,
48 * where type of the first header can be found.
49 *
50 * It skips all well-known exthdrs, and returns pointer to the start
51 * of unparsable area i.e. the first header with unknown type.
52 * If it is not NULL *nexthdr is updated by type/protocol of this header.
53 *
54 * NOTES: - if packet terminated with NEXTHDR_NONE it returns NULL.
55 * - it may return pointer pointing beyond end of packet,
56 * if the last recognized header is truncated in the middle.
57 * - if packet is truncated, so that all parsed headers are skipped,
58 * it returns NULL.
59 * - First fragment header is skipped, not-first ones
60 * are considered as unparsable.
61 * - Reports the offset field of the final fragment header so it is
62 * possible to tell whether this is a first fragment, later fragment,
63 * or not fragmented.
64 * - ESP is unparsable for now and considered like
65 * normal payload protocol.
66 * - Note also special handling of AUTH header. Thanks to IPsec wizards.
67 *
68 * --ANK (980726)
69 */
70
71int ipv6_skip_exthdr(const struct sk_buff *skb, int start, u8 *nexthdrp,
72 __be16 *frag_offp)
73{
74 u8 nexthdr = *nexthdrp;
75
76 *frag_offp = 0;
77
78 while (ipv6_ext_hdr(nexthdr)) {
79 struct ipv6_opt_hdr _hdr, *hp;
80 int hdrlen;
81
82 if (nexthdr == NEXTHDR_NONE)
83 return -1;
84 hp = skb_header_pointer(skb, start, sizeof(_hdr), &_hdr);
85 if (!hp)
86 return -1;
87 if (nexthdr == NEXTHDR_FRAGMENT) {
88 __be16 _frag_off, *fp;
89 fp = skb_header_pointer(skb,
90 start+offsetof(struct frag_hdr,
91 frag_off),
92 sizeof(_frag_off),
93 &_frag_off);
94 if (!fp)
95 return -1;
96
97 *frag_offp = *fp;
98 if (ntohs(*frag_offp) & ~0x7)
99 break;
100 hdrlen = 8;
101 } else if (nexthdr == NEXTHDR_AUTH)
102 hdrlen = (hp->hdrlen+2)<<2;
103 else
104 hdrlen = ipv6_optlen(hp);
105
106 nexthdr = hp->nexthdr;
107 start += hdrlen;
108 }
109
110 *nexthdrp = nexthdr;
111 return start;
112}
113EXPORT_SYMBOL(ipv6_skip_exthdr);
114
115int ipv6_find_tlv(struct sk_buff *skb, int offset, int type)
116{
117 const unsigned char *nh = skb_network_header(skb);
118 int packet_len = skb_tail_pointer(skb) - skb_network_header(skb);
119 struct ipv6_opt_hdr *hdr;
120 int len;
121
122 if (offset + 2 > packet_len)
123 goto bad;
124 hdr = (struct ipv6_opt_hdr *)(nh + offset);
125 len = ((hdr->hdrlen + 1) << 3);
126
127 if (offset + len > packet_len)
128 goto bad;
129
130 offset += 2;
131 len -= 2;
132
133 while (len > 0) {
134 int opttype = nh[offset];
135 int optlen;
136
137 if (opttype == type)
138 return offset;
139
140 switch (opttype) {
141 case IPV6_TLV_PAD1:
142 optlen = 1;
143 break;
144 default:
145 optlen = nh[offset + 1] + 2;
146 if (optlen > len)
147 goto bad;
148 break;
149 }
150 offset += optlen;
151 len -= optlen;
152 }
153 /* not_found */
154 bad:
155 return -1;
156}
157EXPORT_SYMBOL_GPL(ipv6_find_tlv);
158
159/*
160 * find the offset to specified header or the protocol number of last header
161 * if target < 0. "last header" is transport protocol header, ESP, or
162 * "No next header".
163 *
164 * Note that *offset is used as input/output parameter. an if it is not zero,
165 * then it must be a valid offset to an inner IPv6 header. This can be used
166 * to explore inner IPv6 header, eg. ICMPv6 error messages.
167 *
168 * If target header is found, its offset is set in *offset and return protocol
169 * number. Otherwise, return -1.
170 *
171 * If the first fragment doesn't contain the final protocol header or
172 * NEXTHDR_NONE it is considered invalid.
173 *
174 * Note that non-1st fragment is special case that "the protocol number
175 * of last header" is "next header" field in Fragment header. In this case,
176 * *offset is meaningless and fragment offset is stored in *fragoff if fragoff
177 * isn't NULL.
178 *
179 * if flags is not NULL and it's a fragment, then the frag flag
180 * IP6_FH_F_FRAG will be set. If it's an AH header, the
181 * IP6_FH_F_AUTH flag is set and target < 0, then this function will
182 * stop at the AH header. If IP6_FH_F_SKIP_RH flag was passed, then this
183 * function will skip all those routing headers, where segements_left was 0.
184 */
185int ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset,
186 int target, unsigned short *fragoff, int *flags)
187{
188 unsigned int start = skb_network_offset(skb) + sizeof(struct ipv6hdr);
189 u8 nexthdr = ipv6_hdr(skb)->nexthdr;
190 unsigned int len;
191 bool found;
192
193 if (fragoff)
194 *fragoff = 0;
195
196 if (*offset) {
197 struct ipv6hdr _ip6, *ip6;
198
199 ip6 = skb_header_pointer(skb, *offset, sizeof(_ip6), &_ip6);
200 if (!ip6 || (ip6->version != 6)) {
201 printk(KERN_ERR "IPv6 header not found\n");
202 return -EBADMSG;
203 }
204 start = *offset + sizeof(struct ipv6hdr);
205 nexthdr = ip6->nexthdr;
206 }
207 len = skb->len - start;
208
209 do {
210 struct ipv6_opt_hdr _hdr, *hp;
211 unsigned int hdrlen;
212 found = (nexthdr == target);
213
214 if ((!ipv6_ext_hdr(nexthdr)) || nexthdr == NEXTHDR_NONE) {
215 if (target < 0 || found)
216 break;
217 return -ENOENT;
218 }
219
220 hp = skb_header_pointer(skb, start, sizeof(_hdr), &_hdr);
221 if (!hp)
222 return -EBADMSG;
223
224 if (nexthdr == NEXTHDR_ROUTING) {
225 struct ipv6_rt_hdr _rh, *rh;
226
227 rh = skb_header_pointer(skb, start, sizeof(_rh),
228 &_rh);
229 if (!rh)
230 return -EBADMSG;
231
232 if (flags && (*flags & IP6_FH_F_SKIP_RH) &&
233 rh->segments_left == 0)
234 found = false;
235 }
236
237 if (nexthdr == NEXTHDR_FRAGMENT) {
238 unsigned short _frag_off;
239 __be16 *fp;
240
241 if (flags) /* Indicate that this is a fragment */
242 *flags |= IP6_FH_F_FRAG;
243 fp = skb_header_pointer(skb,
244 start+offsetof(struct frag_hdr,
245 frag_off),
246 sizeof(_frag_off),
247 &_frag_off);
248 if (!fp)
249 return -EBADMSG;
250
251 _frag_off = ntohs(*fp) & ~0x7;
252 if (_frag_off) {
253 if (target < 0 &&
254 ((!ipv6_ext_hdr(hp->nexthdr)) ||
255 hp->nexthdr == NEXTHDR_NONE)) {
256 if (fragoff)
257 *fragoff = _frag_off;
258 return hp->nexthdr;
259 }
260 if (!found)
261 return -ENOENT;
262 if (fragoff)
263 *fragoff = _frag_off;
264 break;
265 }
266 hdrlen = 8;
267 } else if (nexthdr == NEXTHDR_AUTH) {
268 if (flags && (*flags & IP6_FH_F_AUTH) && (target < 0))
269 break;
270 hdrlen = (hp->hdrlen + 2) << 2;
271 } else
272 hdrlen = ipv6_optlen(hp);
273
274 if (!found) {
275 nexthdr = hp->nexthdr;
276 len -= hdrlen;
277 start += hdrlen;
278 }
279 } while (!found);
280
281 *offset = start;
282 return nexthdr;
283}
284EXPORT_SYMBOL(ipv6_find_hdr);
285