Adding packet forward test cases involving multiple VMs
[kvmfornfv.git] / kernel / lib / asn1_decoder.c
1 /* Decoder for ASN.1 BER/DER/CER encoded bytestream
2  *
3  * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
4  * Written by David Howells (dhowells@redhat.com)
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public Licence
8  * as published by the Free Software Foundation; either version
9  * 2 of the Licence, or (at your option) any later version.
10  */
11
12 #include <linux/export.h>
13 #include <linux/kernel.h>
14 #include <linux/errno.h>
15 #include <linux/asn1_decoder.h>
16 #include <linux/asn1_ber_bytecode.h>
17
18 static const unsigned char asn1_op_lengths[ASN1_OP__NR] = {
19         /*                                      OPC TAG JMP ACT */
20         [ASN1_OP_MATCH]                         = 1 + 1,
21         [ASN1_OP_MATCH_OR_SKIP]                 = 1 + 1,
22         [ASN1_OP_MATCH_ACT]                     = 1 + 1     + 1,
23         [ASN1_OP_MATCH_ACT_OR_SKIP]             = 1 + 1     + 1,
24         [ASN1_OP_MATCH_JUMP]                    = 1 + 1 + 1,
25         [ASN1_OP_MATCH_JUMP_OR_SKIP]            = 1 + 1 + 1,
26         [ASN1_OP_MATCH_ANY]                     = 1,
27         [ASN1_OP_MATCH_ANY_OR_SKIP]             = 1,
28         [ASN1_OP_MATCH_ANY_ACT]                 = 1         + 1,
29         [ASN1_OP_MATCH_ANY_ACT_OR_SKIP]         = 1         + 1,
30         [ASN1_OP_COND_MATCH_OR_SKIP]            = 1 + 1,
31         [ASN1_OP_COND_MATCH_ACT_OR_SKIP]        = 1 + 1     + 1,
32         [ASN1_OP_COND_MATCH_JUMP_OR_SKIP]       = 1 + 1 + 1,
33         [ASN1_OP_COND_MATCH_ANY]                = 1,
34         [ASN1_OP_COND_MATCH_ANY_OR_SKIP]        = 1,
35         [ASN1_OP_COND_MATCH_ANY_ACT]            = 1         + 1,
36         [ASN1_OP_COND_MATCH_ANY_ACT_OR_SKIP]    = 1         + 1,
37         [ASN1_OP_COND_FAIL]                     = 1,
38         [ASN1_OP_COMPLETE]                      = 1,
39         [ASN1_OP_ACT]                           = 1         + 1,
40         [ASN1_OP_MAYBE_ACT]                     = 1         + 1,
41         [ASN1_OP_RETURN]                        = 1,
42         [ASN1_OP_END_SEQ]                       = 1,
43         [ASN1_OP_END_SEQ_OF]                    = 1     + 1,
44         [ASN1_OP_END_SET]                       = 1,
45         [ASN1_OP_END_SET_OF]                    = 1     + 1,
46         [ASN1_OP_END_SEQ_ACT]                   = 1         + 1,
47         [ASN1_OP_END_SEQ_OF_ACT]                = 1     + 1 + 1,
48         [ASN1_OP_END_SET_ACT]                   = 1         + 1,
49         [ASN1_OP_END_SET_OF_ACT]                = 1     + 1 + 1,
50 };
51
52 /*
53  * Find the length of an indefinite length object
54  * @data: The data buffer
55  * @datalen: The end of the innermost containing element in the buffer
56  * @_dp: The data parse cursor (updated before returning)
57  * @_len: Where to return the size of the element.
58  * @_errmsg: Where to return a pointer to an error message on error
59  */
60 static int asn1_find_indefinite_length(const unsigned char *data, size_t datalen,
61                                        size_t *_dp, size_t *_len,
62                                        const char **_errmsg)
63 {
64         unsigned char tag, tmp;
65         size_t dp = *_dp, len, n;
66         int indef_level = 1;
67
68 next_tag:
69         if (unlikely(datalen - dp < 2)) {
70                 if (datalen == dp)
71                         goto missing_eoc;
72                 goto data_overrun_error;
73         }
74
75         /* Extract a tag from the data */
76         tag = data[dp++];
77         if (tag == ASN1_EOC) {
78                 /* It appears to be an EOC. */
79                 if (data[dp++] != 0)
80                         goto invalid_eoc;
81                 if (--indef_level <= 0) {
82                         *_len = dp - *_dp;
83                         *_dp = dp;
84                         return 0;
85                 }
86                 goto next_tag;
87         }
88
89         if (unlikely((tag & 0x1f) == ASN1_LONG_TAG)) {
90                 do {
91                         if (unlikely(datalen - dp < 2))
92                                 goto data_overrun_error;
93                         tmp = data[dp++];
94                 } while (tmp & 0x80);
95         }
96
97         /* Extract the length */
98         len = data[dp++];
99         if (len <= 0x7f)
100                 goto check_length;
101
102         if (unlikely(len == ASN1_INDEFINITE_LENGTH)) {
103                 /* Indefinite length */
104                 if (unlikely((tag & ASN1_CONS_BIT) == ASN1_PRIM << 5))
105                         goto indefinite_len_primitive;
106                 indef_level++;
107                 goto next_tag;
108         }
109
110         n = len - 0x80;
111         if (unlikely(n > sizeof(len) - 1))
112                 goto length_too_long;
113         if (unlikely(n > datalen - dp))
114                 goto data_overrun_error;
115         len = 0;
116         for (; n > 0; n--) {
117                 len <<= 8;
118                 len |= data[dp++];
119         }
120 check_length:
121         if (len > datalen - dp)
122                 goto data_overrun_error;
123         dp += len;
124         goto next_tag;
125
126 length_too_long:
127         *_errmsg = "Unsupported length";
128         goto error;
129 indefinite_len_primitive:
130         *_errmsg = "Indefinite len primitive not permitted";
131         goto error;
132 invalid_eoc:
133         *_errmsg = "Invalid length EOC";
134         goto error;
135 data_overrun_error:
136         *_errmsg = "Data overrun error";
137         goto error;
138 missing_eoc:
139         *_errmsg = "Missing EOC in indefinite len cons";
140 error:
141         *_dp = dp;
142         return -1;
143 }
144
145 /**
146  * asn1_ber_decoder - Decoder BER/DER/CER ASN.1 according to pattern
147  * @decoder: The decoder definition (produced by asn1_compiler)
148  * @context: The caller's context (to be passed to the action functions)
149  * @data: The encoded data
150  * @datalen: The size of the encoded data
151  *
152  * Decode BER/DER/CER encoded ASN.1 data according to a bytecode pattern
153  * produced by asn1_compiler.  Action functions are called on marked tags to
154  * allow the caller to retrieve significant data.
155  *
156  * LIMITATIONS:
157  *
158  * To keep down the amount of stack used by this function, the following limits
159  * have been imposed:
160  *
161  *  (1) This won't handle datalen > 65535 without increasing the size of the
162  *      cons stack elements and length_too_long checking.
163  *
164  *  (2) The stack of constructed types is 10 deep.  If the depth of non-leaf
165  *      constructed types exceeds this, the decode will fail.
166  *
167  *  (3) The SET type (not the SET OF type) isn't really supported as tracking
168  *      what members of the set have been seen is a pain.
169  */
170 int asn1_ber_decoder(const struct asn1_decoder *decoder,
171                      void *context,
172                      const unsigned char *data,
173                      size_t datalen)
174 {
175         const unsigned char *machine = decoder->machine;
176         const asn1_action_t *actions = decoder->actions;
177         size_t machlen = decoder->machlen;
178         enum asn1_opcode op;
179         unsigned char tag = 0, csp = 0, jsp = 0, optag = 0, hdr = 0;
180         const char *errmsg;
181         size_t pc = 0, dp = 0, tdp = 0, len = 0;
182         int ret;
183
184         unsigned char flags = 0;
185 #define FLAG_INDEFINITE_LENGTH  0x01
186 #define FLAG_MATCHED            0x02
187 #define FLAG_LAST_MATCHED       0x04 /* Last tag matched */
188 #define FLAG_CONS               0x20 /* Corresponds to CONS bit in the opcode tag
189                                       * - ie. whether or not we are going to parse
190                                       *   a compound type.
191                                       */
192
193 #define NR_CONS_STACK 10
194         unsigned short cons_dp_stack[NR_CONS_STACK];
195         unsigned short cons_datalen_stack[NR_CONS_STACK];
196         unsigned char cons_hdrlen_stack[NR_CONS_STACK];
197 #define NR_JUMP_STACK 10
198         unsigned char jump_stack[NR_JUMP_STACK];
199
200         if (datalen > 65535)
201                 return -EMSGSIZE;
202
203 next_op:
204         pr_debug("next_op: pc=\e[32m%zu\e[m/%zu dp=\e[33m%zu\e[m/%zu C=%d J=%d\n",
205                  pc, machlen, dp, datalen, csp, jsp);
206         if (unlikely(pc >= machlen))
207                 goto machine_overrun_error;
208         op = machine[pc];
209         if (unlikely(pc + asn1_op_lengths[op] > machlen))
210                 goto machine_overrun_error;
211
212         /* If this command is meant to match a tag, then do that before
213          * evaluating the command.
214          */
215         if (op <= ASN1_OP__MATCHES_TAG) {
216                 unsigned char tmp;
217
218                 /* Skip conditional matches if possible */
219                 if ((op & ASN1_OP_MATCH__COND && flags & FLAG_MATCHED) ||
220                     (op & ASN1_OP_MATCH__SKIP && dp == datalen)) {
221                         flags &= ~FLAG_LAST_MATCHED;
222                         pc += asn1_op_lengths[op];
223                         goto next_op;
224                 }
225
226                 flags = 0;
227                 hdr = 2;
228
229                 /* Extract a tag from the data */
230                 if (unlikely(dp >= datalen - 1))
231                         goto data_overrun_error;
232                 tag = data[dp++];
233                 if (unlikely((tag & 0x1f) == ASN1_LONG_TAG))
234                         goto long_tag_not_supported;
235
236                 if (op & ASN1_OP_MATCH__ANY) {
237                         pr_debug("- any %02x\n", tag);
238                 } else {
239                         /* Extract the tag from the machine
240                          * - Either CONS or PRIM are permitted in the data if
241                          *   CONS is not set in the op stream, otherwise CONS
242                          *   is mandatory.
243                          */
244                         optag = machine[pc + 1];
245                         flags |= optag & FLAG_CONS;
246
247                         /* Determine whether the tag matched */
248                         tmp = optag ^ tag;
249                         tmp &= ~(optag & ASN1_CONS_BIT);
250                         pr_debug("- match? %02x %02x %02x\n", tag, optag, tmp);
251                         if (tmp != 0) {
252                                 /* All odd-numbered tags are MATCH_OR_SKIP. */
253                                 if (op & ASN1_OP_MATCH__SKIP) {
254                                         pc += asn1_op_lengths[op];
255                                         dp--;
256                                         goto next_op;
257                                 }
258                                 goto tag_mismatch;
259                         }
260                 }
261                 flags |= FLAG_MATCHED;
262
263                 len = data[dp++];
264                 if (len > 0x7f) {
265                         if (unlikely(len == ASN1_INDEFINITE_LENGTH)) {
266                                 /* Indefinite length */
267                                 if (unlikely(!(tag & ASN1_CONS_BIT)))
268                                         goto indefinite_len_primitive;
269                                 flags |= FLAG_INDEFINITE_LENGTH;
270                                 if (unlikely(2 > datalen - dp))
271                                         goto data_overrun_error;
272                         } else {
273                                 int n = len - 0x80;
274                                 if (unlikely(n > 2))
275                                         goto length_too_long;
276                                 if (unlikely(dp >= datalen - n))
277                                         goto data_overrun_error;
278                                 hdr += n;
279                                 for (len = 0; n > 0; n--) {
280                                         len <<= 8;
281                                         len |= data[dp++];
282                                 }
283                                 if (unlikely(len > datalen - dp))
284                                         goto data_overrun_error;
285                         }
286                 }
287
288                 if (flags & FLAG_CONS) {
289                         /* For expected compound forms, we stack the positions
290                          * of the start and end of the data.
291                          */
292                         if (unlikely(csp >= NR_CONS_STACK))
293                                 goto cons_stack_overflow;
294                         cons_dp_stack[csp] = dp;
295                         cons_hdrlen_stack[csp] = hdr;
296                         if (!(flags & FLAG_INDEFINITE_LENGTH)) {
297                                 cons_datalen_stack[csp] = datalen;
298                                 datalen = dp + len;
299                         } else {
300                                 cons_datalen_stack[csp] = 0;
301                         }
302                         csp++;
303                 }
304
305                 pr_debug("- TAG: %02x %zu%s\n",
306                          tag, len, flags & FLAG_CONS ? " CONS" : "");
307                 tdp = dp;
308         }
309
310         /* Decide how to handle the operation */
311         switch (op) {
312         case ASN1_OP_MATCH_ANY_ACT:
313         case ASN1_OP_MATCH_ANY_ACT_OR_SKIP:
314         case ASN1_OP_COND_MATCH_ANY_ACT:
315         case ASN1_OP_COND_MATCH_ANY_ACT_OR_SKIP:
316                 ret = actions[machine[pc + 1]](context, hdr, tag, data + dp, len);
317                 if (ret < 0)
318                         return ret;
319                 goto skip_data;
320
321         case ASN1_OP_MATCH_ACT:
322         case ASN1_OP_MATCH_ACT_OR_SKIP:
323         case ASN1_OP_COND_MATCH_ACT_OR_SKIP:
324                 ret = actions[machine[pc + 2]](context, hdr, tag, data + dp, len);
325                 if (ret < 0)
326                         return ret;
327                 goto skip_data;
328
329         case ASN1_OP_MATCH:
330         case ASN1_OP_MATCH_OR_SKIP:
331         case ASN1_OP_MATCH_ANY:
332         case ASN1_OP_MATCH_ANY_OR_SKIP:
333         case ASN1_OP_COND_MATCH_OR_SKIP:
334         case ASN1_OP_COND_MATCH_ANY:
335         case ASN1_OP_COND_MATCH_ANY_OR_SKIP:
336         skip_data:
337                 if (!(flags & FLAG_CONS)) {
338                         if (flags & FLAG_INDEFINITE_LENGTH) {
339                                 ret = asn1_find_indefinite_length(
340                                         data, datalen, &dp, &len, &errmsg);
341                                 if (ret < 0)
342                                         goto error;
343                         } else {
344                                 dp += len;
345                         }
346                         pr_debug("- LEAF: %zu\n", len);
347                 }
348                 pc += asn1_op_lengths[op];
349                 goto next_op;
350
351         case ASN1_OP_MATCH_JUMP:
352         case ASN1_OP_MATCH_JUMP_OR_SKIP:
353         case ASN1_OP_COND_MATCH_JUMP_OR_SKIP:
354                 pr_debug("- MATCH_JUMP\n");
355                 if (unlikely(jsp == NR_JUMP_STACK))
356                         goto jump_stack_overflow;
357                 jump_stack[jsp++] = pc + asn1_op_lengths[op];
358                 pc = machine[pc + 2];
359                 goto next_op;
360
361         case ASN1_OP_COND_FAIL:
362                 if (unlikely(!(flags & FLAG_MATCHED)))
363                         goto tag_mismatch;
364                 pc += asn1_op_lengths[op];
365                 goto next_op;
366
367         case ASN1_OP_COMPLETE:
368                 if (unlikely(jsp != 0 || csp != 0)) {
369                         pr_err("ASN.1 decoder error: Stacks not empty at completion (%u, %u)\n",
370                                jsp, csp);
371                         return -EBADMSG;
372                 }
373                 return 0;
374
375         case ASN1_OP_END_SET:
376         case ASN1_OP_END_SET_ACT:
377                 if (unlikely(!(flags & FLAG_MATCHED)))
378                         goto tag_mismatch;
379         case ASN1_OP_END_SEQ:
380         case ASN1_OP_END_SET_OF:
381         case ASN1_OP_END_SEQ_OF:
382         case ASN1_OP_END_SEQ_ACT:
383         case ASN1_OP_END_SET_OF_ACT:
384         case ASN1_OP_END_SEQ_OF_ACT:
385                 if (unlikely(csp <= 0))
386                         goto cons_stack_underflow;
387                 csp--;
388                 tdp = cons_dp_stack[csp];
389                 hdr = cons_hdrlen_stack[csp];
390                 len = datalen;
391                 datalen = cons_datalen_stack[csp];
392                 pr_debug("- end cons t=%zu dp=%zu l=%zu/%zu\n",
393                          tdp, dp, len, datalen);
394                 if (datalen == 0) {
395                         /* Indefinite length - check for the EOC. */
396                         datalen = len;
397                         if (unlikely(datalen - dp < 2))
398                                 goto data_overrun_error;
399                         if (data[dp++] != 0) {
400                                 if (op & ASN1_OP_END__OF) {
401                                         dp--;
402                                         csp++;
403                                         pc = machine[pc + 1];
404                                         pr_debug("- continue\n");
405                                         goto next_op;
406                                 }
407                                 goto missing_eoc;
408                         }
409                         if (data[dp++] != 0)
410                                 goto invalid_eoc;
411                         len = dp - tdp - 2;
412                 } else {
413                         if (dp < len && (op & ASN1_OP_END__OF)) {
414                                 datalen = len;
415                                 csp++;
416                                 pc = machine[pc + 1];
417                                 pr_debug("- continue\n");
418                                 goto next_op;
419                         }
420                         if (dp != len)
421                                 goto cons_length_error;
422                         len -= tdp;
423                         pr_debug("- cons len l=%zu d=%zu\n", len, dp - tdp);
424                 }
425
426                 if (op & ASN1_OP_END__ACT) {
427                         unsigned char act;
428                         if (op & ASN1_OP_END__OF)
429                                 act = machine[pc + 2];
430                         else
431                                 act = machine[pc + 1];
432                         ret = actions[act](context, hdr, 0, data + tdp, len);
433                 }
434                 pc += asn1_op_lengths[op];
435                 goto next_op;
436
437         case ASN1_OP_MAYBE_ACT:
438                 if (!(flags & FLAG_LAST_MATCHED)) {
439                         pc += asn1_op_lengths[op];
440                         goto next_op;
441                 }
442         case ASN1_OP_ACT:
443                 ret = actions[machine[pc + 1]](context, hdr, tag, data + tdp, len);
444                 if (ret < 0)
445                         return ret;
446                 pc += asn1_op_lengths[op];
447                 goto next_op;
448
449         case ASN1_OP_RETURN:
450                 if (unlikely(jsp <= 0))
451                         goto jump_stack_underflow;
452                 pc = jump_stack[--jsp];
453                 flags |= FLAG_MATCHED | FLAG_LAST_MATCHED;
454                 goto next_op;
455
456         default:
457                 break;
458         }
459
460         /* Shouldn't reach here */
461         pr_err("ASN.1 decoder error: Found reserved opcode (%u) pc=%zu\n",
462                op, pc);
463         return -EBADMSG;
464
465 data_overrun_error:
466         errmsg = "Data overrun error";
467         goto error;
468 machine_overrun_error:
469         errmsg = "Machine overrun error";
470         goto error;
471 jump_stack_underflow:
472         errmsg = "Jump stack underflow";
473         goto error;
474 jump_stack_overflow:
475         errmsg = "Jump stack overflow";
476         goto error;
477 cons_stack_underflow:
478         errmsg = "Cons stack underflow";
479         goto error;
480 cons_stack_overflow:
481         errmsg = "Cons stack overflow";
482         goto error;
483 cons_length_error:
484         errmsg = "Cons length error";
485         goto error;
486 missing_eoc:
487         errmsg = "Missing EOC in indefinite len cons";
488         goto error;
489 invalid_eoc:
490         errmsg = "Invalid length EOC";
491         goto error;
492 length_too_long:
493         errmsg = "Unsupported length";
494         goto error;
495 indefinite_len_primitive:
496         errmsg = "Indefinite len primitive not permitted";
497         goto error;
498 tag_mismatch:
499         errmsg = "Unexpected tag";
500         goto error;
501 long_tag_not_supported:
502         errmsg = "Long tag not supported";
503 error:
504         pr_debug("\nASN1: %s [m=%zu d=%zu ot=%02x t=%02x l=%zu]\n",
505                  errmsg, pc, dp, optag, tag, len);
506         return -EBADMSG;
507 }
508 EXPORT_SYMBOL_GPL(asn1_ber_decoder);