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ee5d8f4d | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
1da177e4 LT |
2 | /* |
3 | * X.25 Packet Layer release 002 | |
4 | * | |
5 | * This is ALPHA test software. This code may break your machine, | |
6 | * randomly fail to work with new releases, misbehave and/or generally | |
f8e1d201 | 7 | * screw up. It might even work. |
1da177e4 LT |
8 | * |
9 | * This code REQUIRES 2.1.15 or higher | |
10 | * | |
1da177e4 LT |
11 | * History |
12 | * X.25 001 Split from x25_subr.c | |
f8e1d201 | 13 | * mar/20/00 Daniela Squassoni Disabling/enabling of facilities |
1da177e4 | 14 | * negotiation. |
ebc3f64b SP |
15 | * apr/14/05 Shaun Pereira - Allow fast select with no restriction |
16 | * on response. | |
1da177e4 LT |
17 | */ |
18 | ||
b73e9e3c | 19 | #define pr_fmt(fmt) "X25: " fmt |
20 | ||
1da177e4 LT |
21 | #include <linux/kernel.h> |
22 | #include <linux/string.h> | |
23 | #include <linux/skbuff.h> | |
24 | #include <net/sock.h> | |
25 | #include <net/x25.h> | |
26 | ||
95c30430 | 27 | /** |
28 | * x25_parse_facilities - Parse facilities from skb into the facilities structs | |
29 | * | |
30 | * @skb: sk_buff to parse | |
25985edc | 31 | * @facilities: Regular facilities, updated as facilities are found |
95c30430 | 32 | * @dte_facs: ITU DTE facilities, updated as DTE facilities are found |
33 | * @vc_fac_mask: mask is updated with all facilities found | |
34 | * | |
35 | * Return codes: | |
36 | * -1 - Parsing error, caller should drop call and clean up | |
37 | * 0 - Parse OK, this skb has no facilities | |
38 | * >0 - Parse OK, returns the length of the facilities header | |
39 | * | |
1da177e4 | 40 | */ |
a64b7b93 SP |
41 | int x25_parse_facilities(struct sk_buff *skb, struct x25_facilities *facilities, |
42 | struct x25_dte_facilities *dte_facs, unsigned long *vc_fac_mask) | |
1da177e4 | 43 | { |
cb101ed2 | 44 | unsigned char *p; |
f5eb917b | 45 | unsigned int len; |
1da177e4 LT |
46 | |
47 | *vc_fac_mask = 0; | |
48 | ||
a64b7b93 SP |
49 | /* |
50 | * The kernel knows which facilities were set on an incoming call but | |
51 | * currently this information is not available to userspace. Here we | |
52 | * give userspace who read incoming call facilities 0 length to indicate | |
53 | * it wasn't set. | |
54 | */ | |
55 | dte_facs->calling_len = 0; | |
56 | dte_facs->called_len = 0; | |
57 | memset(dte_facs->called_ae, '\0', sizeof(dte_facs->called_ae)); | |
58 | memset(dte_facs->calling_ae, '\0', sizeof(dte_facs->calling_ae)); | |
59 | ||
cb101ed2 | 60 | if (!pskb_may_pull(skb, 1)) |
f5eb917b JH |
61 | return 0; |
62 | ||
cb101ed2 | 63 | len = skb->data[0]; |
f5eb917b | 64 | |
cb101ed2 | 65 | if (!pskb_may_pull(skb, 1 + len)) |
f5eb917b JH |
66 | return -1; |
67 | ||
cb101ed2 MD |
68 | p = skb->data + 1; |
69 | ||
1da177e4 LT |
70 | while (len > 0) { |
71 | switch (*p & X25_FAC_CLASS_MASK) { | |
72 | case X25_FAC_CLASS_A: | |
5ef41308 | 73 | if (len < 2) |
95c30430 | 74 | return -1; |
1da177e4 LT |
75 | switch (*p) { |
76 | case X25_FAC_REVERSE: | |
ebc3f64b SP |
77 | if((p[1] & 0x81) == 0x81) { |
78 | facilities->reverse = p[1] & 0x81; | |
79 | *vc_fac_mask |= X25_MASK_REVERSE; | |
80 | break; | |
81 | } | |
82 | ||
83 | if((p[1] & 0x01) == 0x01) { | |
84 | facilities->reverse = p[1] & 0x01; | |
85 | *vc_fac_mask |= X25_MASK_REVERSE; | |
86 | break; | |
87 | } | |
88 | ||
89 | if((p[1] & 0x80) == 0x80) { | |
90 | facilities->reverse = p[1] & 0x80; | |
91 | *vc_fac_mask |= X25_MASK_REVERSE; | |
92 | break; | |
93 | } | |
94 | ||
95 | if(p[1] == 0x00) { | |
96 | facilities->reverse | |
97 | = X25_DEFAULT_REVERSE; | |
98 | *vc_fac_mask |= X25_MASK_REVERSE; | |
99 | break; | |
100 | } | |
0cea8e28 | 101 | /*fall through */ |
1da177e4 LT |
102 | case X25_FAC_THROUGHPUT: |
103 | facilities->throughput = p[1]; | |
104 | *vc_fac_mask |= X25_MASK_THROUGHPUT; | |
105 | break; | |
a64b7b93 SP |
106 | case X25_MARKER: |
107 | break; | |
1da177e4 | 108 | default: |
b73e9e3c | 109 | pr_debug("unknown facility " |
1da177e4 LT |
110 | "%02X, value %02X\n", |
111 | p[0], p[1]); | |
112 | break; | |
113 | } | |
114 | p += 2; | |
115 | len -= 2; | |
116 | break; | |
117 | case X25_FAC_CLASS_B: | |
5ef41308 | 118 | if (len < 3) |
95c30430 | 119 | return -1; |
1da177e4 LT |
120 | switch (*p) { |
121 | case X25_FAC_PACKET_SIZE: | |
122 | facilities->pacsize_in = p[1]; | |
123 | facilities->pacsize_out = p[2]; | |
124 | *vc_fac_mask |= X25_MASK_PACKET_SIZE; | |
125 | break; | |
126 | case X25_FAC_WINDOW_SIZE: | |
127 | facilities->winsize_in = p[1]; | |
128 | facilities->winsize_out = p[2]; | |
129 | *vc_fac_mask |= X25_MASK_WINDOW_SIZE; | |
130 | break; | |
131 | default: | |
b73e9e3c | 132 | pr_debug("unknown facility " |
1da177e4 LT |
133 | "%02X, values %02X, %02X\n", |
134 | p[0], p[1], p[2]); | |
135 | break; | |
136 | } | |
137 | p += 3; | |
138 | len -= 3; | |
139 | break; | |
140 | case X25_FAC_CLASS_C: | |
5ef41308 | 141 | if (len < 4) |
95c30430 | 142 | return -1; |
b73e9e3c | 143 | pr_debug("unknown facility %02X, " |
1da177e4 LT |
144 | "values %02X, %02X, %02X\n", |
145 | p[0], p[1], p[2], p[3]); | |
146 | p += 4; | |
147 | len -= 4; | |
148 | break; | |
149 | case X25_FAC_CLASS_D: | |
5ef41308 | 150 | if (len < p[1] + 2) |
95c30430 | 151 | return -1; |
a64b7b93 | 152 | switch (*p) { |
f8e1d201 | 153 | case X25_FAC_CALLING_AE: |
a6331d6f | 154 | if (p[1] > X25_MAX_DTE_FACIL_LEN || p[1] <= 1) |
95c30430 | 155 | return -1; |
80aa4e10 DC |
156 | if (p[2] > X25_MAX_AE_LEN) |
157 | return -1; | |
a64b7b93 SP |
158 | dte_facs->calling_len = p[2]; |
159 | memcpy(dte_facs->calling_ae, &p[3], p[1] - 1); | |
160 | *vc_fac_mask |= X25_MASK_CALLING_AE; | |
161 | break; | |
162 | case X25_FAC_CALLED_AE: | |
a6331d6f | 163 | if (p[1] > X25_MAX_DTE_FACIL_LEN || p[1] <= 1) |
95c30430 | 164 | return -1; |
80aa4e10 DC |
165 | if (p[2] > X25_MAX_AE_LEN) |
166 | return -1; | |
a64b7b93 SP |
167 | dte_facs->called_len = p[2]; |
168 | memcpy(dte_facs->called_ae, &p[3], p[1] - 1); | |
169 | *vc_fac_mask |= X25_MASK_CALLED_AE; | |
170 | break; | |
171 | default: | |
b73e9e3c | 172 | pr_debug("unknown facility %02X," |
5ef41308 | 173 | "length %d\n", p[0], p[1]); |
a64b7b93 SP |
174 | break; |
175 | } | |
1da177e4 | 176 | len -= p[1] + 2; |
a64b7b93 | 177 | p += p[1] + 2; |
1da177e4 LT |
178 | break; |
179 | } | |
180 | } | |
181 | ||
182 | return p - skb->data; | |
183 | } | |
184 | ||
185 | /* | |
186 | * Create a set of facilities. | |
187 | */ | |
188 | int x25_create_facilities(unsigned char *buffer, | |
a64b7b93 SP |
189 | struct x25_facilities *facilities, |
190 | struct x25_dte_facilities *dte_facs, unsigned long facil_mask) | |
1da177e4 LT |
191 | { |
192 | unsigned char *p = buffer + 1; | |
193 | int len; | |
194 | ||
195 | if (!facil_mask) { | |
196 | /* | |
197 | * Length of the facilities field in call_req or | |
198 | * call_accept packets | |
199 | */ | |
200 | buffer[0] = 0; | |
201 | len = 1; /* 1 byte for the length field */ | |
202 | return len; | |
203 | } | |
204 | ||
205 | if (facilities->reverse && (facil_mask & X25_MASK_REVERSE)) { | |
206 | *p++ = X25_FAC_REVERSE; | |
ebc3f64b | 207 | *p++ = facilities->reverse; |
1da177e4 LT |
208 | } |
209 | ||
210 | if (facilities->throughput && (facil_mask & X25_MASK_THROUGHPUT)) { | |
211 | *p++ = X25_FAC_THROUGHPUT; | |
212 | *p++ = facilities->throughput; | |
213 | } | |
214 | ||
215 | if ((facilities->pacsize_in || facilities->pacsize_out) && | |
216 | (facil_mask & X25_MASK_PACKET_SIZE)) { | |
217 | *p++ = X25_FAC_PACKET_SIZE; | |
218 | *p++ = facilities->pacsize_in ? : facilities->pacsize_out; | |
219 | *p++ = facilities->pacsize_out ? : facilities->pacsize_in; | |
220 | } | |
221 | ||
222 | if ((facilities->winsize_in || facilities->winsize_out) && | |
223 | (facil_mask & X25_MASK_WINDOW_SIZE)) { | |
224 | *p++ = X25_FAC_WINDOW_SIZE; | |
225 | *p++ = facilities->winsize_in ? : facilities->winsize_out; | |
226 | *p++ = facilities->winsize_out ? : facilities->winsize_in; | |
227 | } | |
228 | ||
a64b7b93 SP |
229 | if (facil_mask & (X25_MASK_CALLING_AE|X25_MASK_CALLED_AE)) { |
230 | *p++ = X25_MARKER; | |
231 | *p++ = X25_DTE_SERVICES; | |
232 | } | |
233 | ||
234 | if (dte_facs->calling_len && (facil_mask & X25_MASK_CALLING_AE)) { | |
95c96174 | 235 | unsigned int bytecount = (dte_facs->calling_len + 1) >> 1; |
a64b7b93 SP |
236 | *p++ = X25_FAC_CALLING_AE; |
237 | *p++ = 1 + bytecount; | |
238 | *p++ = dte_facs->calling_len; | |
239 | memcpy(p, dte_facs->calling_ae, bytecount); | |
240 | p += bytecount; | |
241 | } | |
242 | ||
243 | if (dte_facs->called_len && (facil_mask & X25_MASK_CALLED_AE)) { | |
95c96174 | 244 | unsigned int bytecount = (dte_facs->called_len % 2) ? |
a64b7b93 SP |
245 | dte_facs->called_len / 2 + 1 : |
246 | dte_facs->called_len / 2; | |
247 | *p++ = X25_FAC_CALLED_AE; | |
248 | *p++ = 1 + bytecount; | |
249 | *p++ = dte_facs->called_len; | |
250 | memcpy(p, dte_facs->called_ae, bytecount); | |
251 | p+=bytecount; | |
252 | } | |
253 | ||
1da177e4 LT |
254 | len = p - buffer; |
255 | buffer[0] = len - 1; | |
256 | ||
257 | return len; | |
258 | } | |
259 | ||
260 | /* | |
261 | * Try to reach a compromise on a set of facilities. | |
262 | * | |
263 | * The only real problem is with reverse charging. | |
264 | */ | |
265 | int x25_negotiate_facilities(struct sk_buff *skb, struct sock *sk, | |
a64b7b93 | 266 | struct x25_facilities *new, struct x25_dte_facilities *dte) |
1da177e4 LT |
267 | { |
268 | struct x25_sock *x25 = x25_sk(sk); | |
269 | struct x25_facilities *ours = &x25->facilities; | |
270 | struct x25_facilities theirs; | |
271 | int len; | |
272 | ||
273 | memset(&theirs, 0, sizeof(theirs)); | |
274 | memcpy(new, ours, sizeof(*new)); | |
79e48650 | 275 | memset(dte, 0, sizeof(*dte)); |
1da177e4 | 276 | |
a64b7b93 | 277 | len = x25_parse_facilities(skb, &theirs, dte, &x25->vc_facil_mask); |
f5eb917b JH |
278 | if (len < 0) |
279 | return len; | |
1da177e4 LT |
280 | |
281 | /* | |
282 | * They want reverse charging, we won't accept it. | |
283 | */ | |
ebc3f64b | 284 | if ((theirs.reverse & 0x01 ) && (ours->reverse & 0x01)) { |
d2e7543c | 285 | SOCK_DEBUG(sk, "X.25: rejecting reverse charging request\n"); |
1da177e4 LT |
286 | return -1; |
287 | } | |
288 | ||
289 | new->reverse = theirs.reverse; | |
290 | ||
291 | if (theirs.throughput) { | |
ddd0451f JH |
292 | int theirs_in = theirs.throughput & 0x0f; |
293 | int theirs_out = theirs.throughput & 0xf0; | |
294 | int ours_in = ours->throughput & 0x0f; | |
295 | int ours_out = ours->throughput & 0xf0; | |
296 | if (!ours_in || theirs_in < ours_in) { | |
297 | SOCK_DEBUG(sk, "X.25: inbound throughput negotiated\n"); | |
298 | new->throughput = (new->throughput & 0xf0) | theirs_in; | |
299 | } | |
300 | if (!ours_out || theirs_out < ours_out) { | |
301 | SOCK_DEBUG(sk, | |
302 | "X.25: outbound throughput negotiated\n"); | |
303 | new->throughput = (new->throughput & 0x0f) | theirs_out; | |
1da177e4 LT |
304 | } |
305 | } | |
306 | ||
307 | if (theirs.pacsize_in && theirs.pacsize_out) { | |
308 | if (theirs.pacsize_in < ours->pacsize_in) { | |
d2e7543c | 309 | SOCK_DEBUG(sk, "X.25: packet size inwards negotiated down\n"); |
1da177e4 LT |
310 | new->pacsize_in = theirs.pacsize_in; |
311 | } | |
312 | if (theirs.pacsize_out < ours->pacsize_out) { | |
d2e7543c | 313 | SOCK_DEBUG(sk, "X.25: packet size outwards negotiated down\n"); |
1da177e4 LT |
314 | new->pacsize_out = theirs.pacsize_out; |
315 | } | |
316 | } | |
317 | ||
318 | if (theirs.winsize_in && theirs.winsize_out) { | |
319 | if (theirs.winsize_in < ours->winsize_in) { | |
d2e7543c | 320 | SOCK_DEBUG(sk, "X.25: window size inwards negotiated down\n"); |
1da177e4 LT |
321 | new->winsize_in = theirs.winsize_in; |
322 | } | |
323 | if (theirs.winsize_out < ours->winsize_out) { | |
d2e7543c | 324 | SOCK_DEBUG(sk, "X.25: window size outwards negotiated down\n"); |
1da177e4 LT |
325 | new->winsize_out = theirs.winsize_out; |
326 | } | |
327 | } | |
328 | ||
329 | return len; | |
330 | } | |
331 | ||
332 | /* | |
f8e1d201 | 333 | * Limit values of certain facilities according to the capability of the |
1da177e4 LT |
334 | * currently attached x25 link. |
335 | */ | |
336 | void x25_limit_facilities(struct x25_facilities *facilities, | |
337 | struct x25_neigh *nb) | |
338 | { | |
339 | ||
340 | if (!nb->extended) { | |
341 | if (facilities->winsize_in > 7) { | |
b73e9e3c | 342 | pr_debug("incoming winsize limited to 7\n"); |
1da177e4 LT |
343 | facilities->winsize_in = 7; |
344 | } | |
345 | if (facilities->winsize_out > 7) { | |
346 | facilities->winsize_out = 7; | |
b73e9e3c | 347 | pr_debug("outgoing winsize limited to 7\n"); |
1da177e4 LT |
348 | } |
349 | } | |
350 | } |