Merge branch 'for-linus-5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad...
[linux-2.6-microblaze.git] / net / x25 / x25_facilities.c
1 // SPDX-License-Identifier: GPL-2.0-or-later
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
7  *      screw up. It might even work.
8  *
9  *      This code REQUIRES 2.1.15 or higher
10  *
11  *      History
12  *      X.25 001        Split from x25_subr.c
13  *      mar/20/00       Daniela Squassoni Disabling/enabling of facilities
14  *                                        negotiation.
15  *      apr/14/05       Shaun Pereira - Allow fast select with no restriction
16  *                                      on response.
17  */
18
19 #define pr_fmt(fmt) "X25: " fmt
20
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
27 /**
28  * x25_parse_facilities - Parse facilities from skb into the facilities structs
29  *
30  * @skb: sk_buff to parse
31  * @facilities: Regular facilities, updated as facilities are found
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  *
40  */
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)
43 {
44         unsigned char *p;
45         unsigned int len;
46
47         *vc_fac_mask = 0;
48
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
60         if (!pskb_may_pull(skb, 1))
61                 return 0;
62
63         len = skb->data[0];
64
65         if (!pskb_may_pull(skb, 1 + len))
66                 return -1;
67
68         p = skb->data + 1;
69
70         while (len > 0) {
71                 switch (*p & X25_FAC_CLASS_MASK) {
72                 case X25_FAC_CLASS_A:
73                         if (len < 2)
74                                 return -1;
75                         switch (*p) {
76                         case X25_FAC_REVERSE:
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                                 }
101                                 /*fall through */
102                         case X25_FAC_THROUGHPUT:
103                                 facilities->throughput = p[1];
104                                 *vc_fac_mask |= X25_MASK_THROUGHPUT;
105                                 break;
106                         case X25_MARKER:
107                                 break;
108                         default:
109                                 pr_debug("unknown facility "
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:
118                         if (len < 3)
119                                 return -1;
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:
132                                 pr_debug("unknown facility "
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:
141                         if (len < 4)
142                                 return -1;
143                         pr_debug("unknown facility %02X, "
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:
150                         if (len < p[1] + 2)
151                                 return -1;
152                         switch (*p) {
153                         case X25_FAC_CALLING_AE:
154                                 if (p[1] > X25_MAX_DTE_FACIL_LEN || p[1] <= 1)
155                                         return -1;
156                                 if (p[2] > X25_MAX_AE_LEN)
157                                         return -1;
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:
163                                 if (p[1] > X25_MAX_DTE_FACIL_LEN || p[1] <= 1)
164                                         return -1;
165                                 if (p[2] > X25_MAX_AE_LEN)
166                                         return -1;
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:
172                                 pr_debug("unknown facility %02X,"
173                                         "length %d\n", p[0], p[1]);
174                                 break;
175                         }
176                         len -= p[1] + 2;
177                         p += p[1] + 2;
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,
189                 struct x25_facilities *facilities,
190                 struct x25_dte_facilities *dte_facs, unsigned long facil_mask)
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;
207                 *p++ = facilities->reverse;
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
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)) {
235                 unsigned int bytecount = (dte_facs->calling_len + 1) >> 1;
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)) {
244                 unsigned int bytecount = (dte_facs->called_len % 2) ?
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
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,
266                 struct x25_facilities *new, struct x25_dte_facilities *dte)
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));
275         memset(dte, 0, sizeof(*dte));
276
277         len = x25_parse_facilities(skb, &theirs, dte, &x25->vc_facil_mask);
278         if (len < 0)
279                 return len;
280
281         /*
282          *      They want reverse charging, we won't accept it.
283          */
284         if ((theirs.reverse & 0x01 ) && (ours->reverse & 0x01)) {
285                 SOCK_DEBUG(sk, "X.25: rejecting reverse charging request\n");
286                 return -1;
287         }
288
289         new->reverse = theirs.reverse;
290
291         if (theirs.throughput) {
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;
304                 }
305         }
306
307         if (theirs.pacsize_in && theirs.pacsize_out) {
308                 if (theirs.pacsize_in < ours->pacsize_in) {
309                         SOCK_DEBUG(sk, "X.25: packet size inwards negotiated down\n");
310                         new->pacsize_in = theirs.pacsize_in;
311                 }
312                 if (theirs.pacsize_out < ours->pacsize_out) {
313                         SOCK_DEBUG(sk, "X.25: packet size outwards negotiated down\n");
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) {
320                         SOCK_DEBUG(sk, "X.25: window size inwards negotiated down\n");
321                         new->winsize_in = theirs.winsize_in;
322                 }
323                 if (theirs.winsize_out < ours->winsize_out) {
324                         SOCK_DEBUG(sk, "X.25: window size outwards negotiated down\n");
325                         new->winsize_out = theirs.winsize_out;
326                 }
327         }
328
329         return len;
330 }
331
332 /*
333  *      Limit values of certain facilities according to the capability of the
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) {
342                         pr_debug("incoming winsize limited to 7\n");
343                         facilities->winsize_in = 7;
344                 }
345                 if (facilities->winsize_out > 7) {
346                         facilities->winsize_out = 7;
347                         pr_debug("outgoing winsize limited to 7\n");
348                 }
349         }
350 }