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1 | /* | |
2 | * X.25 Packet Layer release 002 | |
3 | * | |
4 | * This is ALPHA test software. This code may break your machine, | |
5 | * randomly fail to work with new releases, misbehave and/or generally | |
6 | * screw up. It might even work. | |
7 | * | |
8 | * This code REQUIRES 2.1.15 or higher | |
9 | * | |
10 | * This module: | |
11 | * This module is free software; you can redistribute it and/or | |
12 | * modify it under the terms of the GNU General Public License | |
13 | * as published by the Free Software Foundation; either version | |
14 | * 2 of the License, or (at your option) any later version. | |
15 | * | |
16 | * History | |
17 | * X.25 001 Split from x25_subr.c | |
18 | * mar/20/00 Daniela Squassoni Disabling/enabling of facilities | |
19 | * negotiation. | |
20 | * apr/14/05 Shaun Pereira - Allow fast select with no restriction | |
21 | * on response. | |
22 | */ | |
23 | ||
24 | #define pr_fmt(fmt) "X25: " fmt | |
25 | ||
26 | #include <linux/kernel.h> | |
27 | #include <linux/string.h> | |
28 | #include <linux/skbuff.h> | |
29 | #include <net/sock.h> | |
30 | #include <net/x25.h> | |
31 | ||
32 | /** | |
33 | * x25_parse_facilities - Parse facilities from skb into the facilities structs | |
34 | * | |
35 | * @skb: sk_buff to parse | |
36 | * @facilities: Regular facilities, updated as facilities are found | |
37 | * @dte_facs: ITU DTE facilities, updated as DTE facilities are found | |
38 | * @vc_fac_mask: mask is updated with all facilities found | |
39 | * | |
40 | * Return codes: | |
41 | * -1 - Parsing error, caller should drop call and clean up | |
42 | * 0 - Parse OK, this skb has no facilities | |
43 | * >0 - Parse OK, returns the length of the facilities header | |
44 | * | |
45 | */ | |
46 | int x25_parse_facilities(struct sk_buff *skb, struct x25_facilities *facilities, | |
47 | struct x25_dte_facilities *dte_facs, unsigned long *vc_fac_mask) | |
48 | { | |
49 | unsigned char *p; | |
50 | unsigned int len; | |
51 | ||
52 | *vc_fac_mask = 0; | |
53 | ||
54 | /* | |
55 | * The kernel knows which facilities were set on an incoming call but | |
56 | * currently this information is not available to userspace. Here we | |
57 | * give userspace who read incoming call facilities 0 length to indicate | |
58 | * it wasn't set. | |
59 | */ | |
60 | dte_facs->calling_len = 0; | |
61 | dte_facs->called_len = 0; | |
62 | memset(dte_facs->called_ae, '\0', sizeof(dte_facs->called_ae)); | |
63 | memset(dte_facs->calling_ae, '\0', sizeof(dte_facs->calling_ae)); | |
64 | ||
65 | if (!pskb_may_pull(skb, 1)) | |
66 | return 0; | |
67 | ||
68 | len = skb->data[0]; | |
69 | ||
70 | if (!pskb_may_pull(skb, 1 + len)) | |
71 | return -1; | |
72 | ||
73 | p = skb->data + 1; | |
74 | ||
75 | while (len > 0) { | |
76 | switch (*p & X25_FAC_CLASS_MASK) { | |
77 | case X25_FAC_CLASS_A: | |
78 | if (len < 2) | |
79 | return -1; | |
80 | switch (*p) { | |
81 | case X25_FAC_REVERSE: | |
82 | if((p[1] & 0x81) == 0x81) { | |
83 | facilities->reverse = p[1] & 0x81; | |
84 | *vc_fac_mask |= X25_MASK_REVERSE; | |
85 | break; | |
86 | } | |
87 | ||
88 | if((p[1] & 0x01) == 0x01) { | |
89 | facilities->reverse = p[1] & 0x01; | |
90 | *vc_fac_mask |= X25_MASK_REVERSE; | |
91 | break; | |
92 | } | |
93 | ||
94 | if((p[1] & 0x80) == 0x80) { | |
95 | facilities->reverse = p[1] & 0x80; | |
96 | *vc_fac_mask |= X25_MASK_REVERSE; | |
97 | break; | |
98 | } | |
99 | ||
100 | if(p[1] == 0x00) { | |
101 | facilities->reverse | |
102 | = X25_DEFAULT_REVERSE; | |
103 | *vc_fac_mask |= X25_MASK_REVERSE; | |
104 | break; | |
105 | } | |
106 | ||
107 | case X25_FAC_THROUGHPUT: | |
108 | facilities->throughput = p[1]; | |
109 | *vc_fac_mask |= X25_MASK_THROUGHPUT; | |
110 | break; | |
111 | case X25_MARKER: | |
112 | break; | |
113 | default: | |
114 | pr_debug("unknown facility " | |
115 | "%02X, value %02X\n", | |
116 | p[0], p[1]); | |
117 | break; | |
118 | } | |
119 | p += 2; | |
120 | len -= 2; | |
121 | break; | |
122 | case X25_FAC_CLASS_B: | |
123 | if (len < 3) | |
124 | return -1; | |
125 | switch (*p) { | |
126 | case X25_FAC_PACKET_SIZE: | |
127 | facilities->pacsize_in = p[1]; | |
128 | facilities->pacsize_out = p[2]; | |
129 | *vc_fac_mask |= X25_MASK_PACKET_SIZE; | |
130 | break; | |
131 | case X25_FAC_WINDOW_SIZE: | |
132 | facilities->winsize_in = p[1]; | |
133 | facilities->winsize_out = p[2]; | |
134 | *vc_fac_mask |= X25_MASK_WINDOW_SIZE; | |
135 | break; | |
136 | default: | |
137 | pr_debug("unknown facility " | |
138 | "%02X, values %02X, %02X\n", | |
139 | p[0], p[1], p[2]); | |
140 | break; | |
141 | } | |
142 | p += 3; | |
143 | len -= 3; | |
144 | break; | |
145 | case X25_FAC_CLASS_C: | |
146 | if (len < 4) | |
147 | return -1; | |
148 | pr_debug("unknown facility %02X, " | |
149 | "values %02X, %02X, %02X\n", | |
150 | p[0], p[1], p[2], p[3]); | |
151 | p += 4; | |
152 | len -= 4; | |
153 | break; | |
154 | case X25_FAC_CLASS_D: | |
155 | if (len < p[1] + 2) | |
156 | return -1; | |
157 | switch (*p) { | |
158 | case X25_FAC_CALLING_AE: | |
159 | if (p[1] > X25_MAX_DTE_FACIL_LEN || p[1] <= 1) | |
160 | return -1; | |
161 | if (p[2] > X25_MAX_AE_LEN) | |
162 | return -1; | |
163 | dte_facs->calling_len = p[2]; | |
164 | memcpy(dte_facs->calling_ae, &p[3], p[1] - 1); | |
165 | *vc_fac_mask |= X25_MASK_CALLING_AE; | |
166 | break; | |
167 | case X25_FAC_CALLED_AE: | |
168 | if (p[1] > X25_MAX_DTE_FACIL_LEN || p[1] <= 1) | |
169 | return -1; | |
170 | if (p[2] > X25_MAX_AE_LEN) | |
171 | return -1; | |
172 | dte_facs->called_len = p[2]; | |
173 | memcpy(dte_facs->called_ae, &p[3], p[1] - 1); | |
174 | *vc_fac_mask |= X25_MASK_CALLED_AE; | |
175 | break; | |
176 | default: | |
177 | pr_debug("unknown facility %02X," | |
178 | "length %d\n", p[0], p[1]); | |
179 | break; | |
180 | } | |
181 | len -= p[1] + 2; | |
182 | p += p[1] + 2; | |
183 | break; | |
184 | } | |
185 | } | |
186 | ||
187 | return p - skb->data; | |
188 | } | |
189 | ||
190 | /* | |
191 | * Create a set of facilities. | |
192 | */ | |
193 | int x25_create_facilities(unsigned char *buffer, | |
194 | struct x25_facilities *facilities, | |
195 | struct x25_dte_facilities *dte_facs, unsigned long facil_mask) | |
196 | { | |
197 | unsigned char *p = buffer + 1; | |
198 | int len; | |
199 | ||
200 | if (!facil_mask) { | |
201 | /* | |
202 | * Length of the facilities field in call_req or | |
203 | * call_accept packets | |
204 | */ | |
205 | buffer[0] = 0; | |
206 | len = 1; /* 1 byte for the length field */ | |
207 | return len; | |
208 | } | |
209 | ||
210 | if (facilities->reverse && (facil_mask & X25_MASK_REVERSE)) { | |
211 | *p++ = X25_FAC_REVERSE; | |
212 | *p++ = facilities->reverse; | |
213 | } | |
214 | ||
215 | if (facilities->throughput && (facil_mask & X25_MASK_THROUGHPUT)) { | |
216 | *p++ = X25_FAC_THROUGHPUT; | |
217 | *p++ = facilities->throughput; | |
218 | } | |
219 | ||
220 | if ((facilities->pacsize_in || facilities->pacsize_out) && | |
221 | (facil_mask & X25_MASK_PACKET_SIZE)) { | |
222 | *p++ = X25_FAC_PACKET_SIZE; | |
223 | *p++ = facilities->pacsize_in ? : facilities->pacsize_out; | |
224 | *p++ = facilities->pacsize_out ? : facilities->pacsize_in; | |
225 | } | |
226 | ||
227 | if ((facilities->winsize_in || facilities->winsize_out) && | |
228 | (facil_mask & X25_MASK_WINDOW_SIZE)) { | |
229 | *p++ = X25_FAC_WINDOW_SIZE; | |
230 | *p++ = facilities->winsize_in ? : facilities->winsize_out; | |
231 | *p++ = facilities->winsize_out ? : facilities->winsize_in; | |
232 | } | |
233 | ||
234 | if (facil_mask & (X25_MASK_CALLING_AE|X25_MASK_CALLED_AE)) { | |
235 | *p++ = X25_MARKER; | |
236 | *p++ = X25_DTE_SERVICES; | |
237 | } | |
238 | ||
239 | if (dte_facs->calling_len && (facil_mask & X25_MASK_CALLING_AE)) { | |
240 | unsigned int bytecount = (dte_facs->calling_len + 1) >> 1; | |
241 | *p++ = X25_FAC_CALLING_AE; | |
242 | *p++ = 1 + bytecount; | |
243 | *p++ = dte_facs->calling_len; | |
244 | memcpy(p, dte_facs->calling_ae, bytecount); | |
245 | p += bytecount; | |
246 | } | |
247 | ||
248 | if (dte_facs->called_len && (facil_mask & X25_MASK_CALLED_AE)) { | |
249 | unsigned int bytecount = (dte_facs->called_len % 2) ? | |
250 | dte_facs->called_len / 2 + 1 : | |
251 | dte_facs->called_len / 2; | |
252 | *p++ = X25_FAC_CALLED_AE; | |
253 | *p++ = 1 + bytecount; | |
254 | *p++ = dte_facs->called_len; | |
255 | memcpy(p, dte_facs->called_ae, bytecount); | |
256 | p+=bytecount; | |
257 | } | |
258 | ||
259 | len = p - buffer; | |
260 | buffer[0] = len - 1; | |
261 | ||
262 | return len; | |
263 | } | |
264 | ||
265 | /* | |
266 | * Try to reach a compromise on a set of facilities. | |
267 | * | |
268 | * The only real problem is with reverse charging. | |
269 | */ | |
270 | int x25_negotiate_facilities(struct sk_buff *skb, struct sock *sk, | |
271 | struct x25_facilities *new, struct x25_dte_facilities *dte) | |
272 | { | |
273 | struct x25_sock *x25 = x25_sk(sk); | |
274 | struct x25_facilities *ours = &x25->facilities; | |
275 | struct x25_facilities theirs; | |
276 | int len; | |
277 | ||
278 | memset(&theirs, 0, sizeof(theirs)); | |
279 | memcpy(new, ours, sizeof(*new)); | |
280 | memset(dte, 0, sizeof(*dte)); | |
281 | ||
282 | len = x25_parse_facilities(skb, &theirs, dte, &x25->vc_facil_mask); | |
283 | if (len < 0) | |
284 | return len; | |
285 | ||
286 | /* | |
287 | * They want reverse charging, we won't accept it. | |
288 | */ | |
289 | if ((theirs.reverse & 0x01 ) && (ours->reverse & 0x01)) { | |
290 | SOCK_DEBUG(sk, "X.25: rejecting reverse charging request\n"); | |
291 | return -1; | |
292 | } | |
293 | ||
294 | new->reverse = theirs.reverse; | |
295 | ||
296 | if (theirs.throughput) { | |
297 | int theirs_in = theirs.throughput & 0x0f; | |
298 | int theirs_out = theirs.throughput & 0xf0; | |
299 | int ours_in = ours->throughput & 0x0f; | |
300 | int ours_out = ours->throughput & 0xf0; | |
301 | if (!ours_in || theirs_in < ours_in) { | |
302 | SOCK_DEBUG(sk, "X.25: inbound throughput negotiated\n"); | |
303 | new->throughput = (new->throughput & 0xf0) | theirs_in; | |
304 | } | |
305 | if (!ours_out || theirs_out < ours_out) { | |
306 | SOCK_DEBUG(sk, | |
307 | "X.25: outbound throughput negotiated\n"); | |
308 | new->throughput = (new->throughput & 0x0f) | theirs_out; | |
309 | } | |
310 | } | |
311 | ||
312 | if (theirs.pacsize_in && theirs.pacsize_out) { | |
313 | if (theirs.pacsize_in < ours->pacsize_in) { | |
314 | SOCK_DEBUG(sk, "X.25: packet size inwards negotiated down\n"); | |
315 | new->pacsize_in = theirs.pacsize_in; | |
316 | } | |
317 | if (theirs.pacsize_out < ours->pacsize_out) { | |
318 | SOCK_DEBUG(sk, "X.25: packet size outwards negotiated down\n"); | |
319 | new->pacsize_out = theirs.pacsize_out; | |
320 | } | |
321 | } | |
322 | ||
323 | if (theirs.winsize_in && theirs.winsize_out) { | |
324 | if (theirs.winsize_in < ours->winsize_in) { | |
325 | SOCK_DEBUG(sk, "X.25: window size inwards negotiated down\n"); | |
326 | new->winsize_in = theirs.winsize_in; | |
327 | } | |
328 | if (theirs.winsize_out < ours->winsize_out) { | |
329 | SOCK_DEBUG(sk, "X.25: window size outwards negotiated down\n"); | |
330 | new->winsize_out = theirs.winsize_out; | |
331 | } | |
332 | } | |
333 | ||
334 | return len; | |
335 | } | |
336 | ||
337 | /* | |
338 | * Limit values of certain facilities according to the capability of the | |
339 | * currently attached x25 link. | |
340 | */ | |
341 | void x25_limit_facilities(struct x25_facilities *facilities, | |
342 | struct x25_neigh *nb) | |
343 | { | |
344 | ||
345 | if (!nb->extended) { | |
346 | if (facilities->winsize_in > 7) { | |
347 | pr_debug("incoming winsize limited to 7\n"); | |
348 | facilities->winsize_in = 7; | |
349 | } | |
350 | if (facilities->winsize_out > 7) { | |
351 | facilities->winsize_out = 7; | |
352 | pr_debug("outgoing winsize limited to 7\n"); | |
353 | } | |
354 | } | |
355 | } |