1 .\" $OpenBSD: crypto.9,v 1.19 2002/07/16 06:31:57 angelos Exp $
3 .\" The author of this manual page is Angelos D. Keromytis (angelos@cis.upenn.edu)
5 .\" Copyright (c) 2000, 2001 Angelos D. Keromytis
7 .\" Permission to use, copy, and modify this software with or without fee
8 .\" is hereby granted, provided that this entire notice is included in
9 .\" all source code copies of any software which is or includes a copy or
10 .\" modification of this software.
12 .\" THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
13 .\" IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY
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15 .\" MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR
25 .Nd API for cryptographic services in the kernel
27 .In opencrypto/cryptodev.h
29 .Fn crypto_get_driverid uint8_t
31 .Fn crypto_register uint32_t int uint16_t uint32_t "int \*[lp]*\*[rp]\*[lp]void *, uint32_t *, struct cryptoini *\*[rp]" "int \*[lp]*\*[rp]\*[lp]void *, uint64_t\*[rp]" "int \*[lp]*\*[rp]\*[lp]void *, struct cryptop *\*[rp]" "void *"
33 .Fn crypto_kregister uint32_t int uint32_t "int \*[lp]*\*[rp]\*[lp]void *, struct cryptkop *\*[rp]" "void *"
35 .Fn crypto_unregister uint32_t int
37 .Fn crypto_unregister_all uint32_t
39 .Fn crypto_done "struct cryptop *"
41 .Fn crypto_kdone "struct cryptkop *"
43 .Fn crypto_newsession "uint64_t *" "struct cryptoini *" int
45 .Fn crypto_freesession uint64_t
47 .Fn crypto_dispatch "struct cryptop *"
49 .Fn crypto_kdispatch "struct cryptkop *"
51 .Fn crypto_unblock uint32_t int
52 .Ft "struct cryptop *"
55 .Fn crypto_freereq void
57 #define CRYPTO_SYMQ 0x1
58 #define CRYPTO_ASYMQ 0x2
60 #define EALG_MAX_BLOCK_LEN 16
67 uint8_t cri_iv[EALG_MAX_BLOCK_LEN];
68 struct cryptoini *cri_next;
76 struct cryptoini CRD_INI;
77 #define crd_iv CRD_INI.cri_iv
78 #define crd_key CRD_INI.cri_key
79 #define crd_alg CRD_INI.cri_alg
80 #define crd_klen CRD_INI.cri_klen
81 struct cryptodesc *crd_next;
85 TAILQ_ENTRY(cryptop) crp_next;
93 struct cryptodesc *crp_desc;
94 int (*crp_callback) (struct cryptop *);
103 #define CRK_MAXPARAM 8
106 TAILQ_ENTRY(cryptkop) krp_next;
107 u_int krp_op; /* ie. CRK_MOD_EXP or other */
108 u_int krp_status; /* return status */
109 u_short krp_iparams; /* # of input parameters */
110 u_short krp_oparams; /* # of output parameters */
112 struct crparam krp_param[CRK_MAXPARAM];
113 int (*krp_callback)(struct cryptkop *);
118 is a framework for drivers of cryptographic hardware to register with
121 (other kernel subsystems, and
124 device) are able to make use of it.
125 Drivers register with the framework the algorithms they support,
126 and provide entry points (functions) the framework may call to
127 establish, use, and tear down sessions.
128 Sessions are used to cache cryptographic information in a particular driver
129 (or associated hardware), so initialization is not needed with every request.
130 Consumers of cryptographic services pass a set of
131 descriptors that instruct the framework (and the drivers registered
132 with it) of the operations that should be applied on the data (more
133 than one cryptographic operation can be requested).
135 Keying operations are supported as well.
136 Unlike the symmetric operators described above,
137 these sessionless commands perform mathematical operations using
138 input and output parameters.
140 Since the consumers may not be associated with a process, drivers may
143 The same holds for the framework.
144 Thus, a callback mechanism is used
145 to notify a consumer that a request has been completed (the
146 callback is specified by the consumer on a per-request basis).
147 The callback is invoked by the framework whether the request was
148 successfully completed or not.
149 An error indication is provided in the latter case.
150 A specific error code,
152 is used to indicate that a session number has changed and that the
153 request may be re-submitted immediately with the new session number.
154 Errors are only returned to the invoking function if not
155 enough information to call the callback is available (meaning, there
156 was a fatal error in verifying the arguments).
157 For session initialization and teardown there is no callback mechanism used.
160 .Fn crypto_newsession
161 routine is called by consumers of cryptographic services (such as the
163 stack) that wish to establish a new session with the framework.
164 On success, the first argument will contain the Session Identifier (SID).
165 The second argument contains all the necessary information for
166 the driver to establish the session.
167 The third argument indicates whether a
168 hardware driver (1) should be used or not (0).
169 The various fields in the
172 .Bl -tag -width ".Va cri_next"
174 Contains an algorithm identifier.
175 Currently supported algorithms are:
177 .Bl -tag -width ".Dv CRYPTO_RIPEMD160_HMAC" -compact
178 .It Dv CRYPTO_AES_128_NIST_GMAC
179 .It Dv CRYPTO_AES_192_NIST_GMAC
180 .It Dv CRYPTO_AES_256_NIST_GMAC
181 .It Dv CRYPTO_AES_CBC
182 .It Dv CRYPTO_AES_ICM
183 .It Dv CRYPTO_AES_NIST_GCM_16
184 .It Dv CRYPTO_AES_NIST_GMAC
185 .It Dv CRYPTO_AES_XTS
187 .It Dv CRYPTO_BLF_CBC
188 .It Dv CRYPTO_CAMELLIA_CBC
189 .It Dv CRYPTO_CAST_CBC
190 .It Dv CRYPTO_DEFLATE_COMP
191 .It Dv CRYPTO_DES_CBC
192 .It Dv CRYPTO_3DES_CBC
194 .It Dv CRYPTO_MD5_HMAC
195 .It Dv CRYPTO_MD5_KPDK
196 .It Dv CRYPTO_NULL_HMAC
197 .It Dv CRYPTO_NULL_CBC
198 .It Dv CRYPTO_RIPEMD160_HMAC
200 .It Dv CRYPTO_SHA1_HMAC
201 .It Dv CRYPTO_SHA1_KPDK
202 .It Dv CRYPTO_SHA2_256_HMAC
203 .It Dv CRYPTO_SHA2_384_HMAC
204 .It Dv CRYPTO_SHA2_512_HMAC
205 .It Dv CRYPTO_SKIPJACK_CBC
208 Specifies the length of the key in bits, for variable-size key
211 Specifies how many bytes from the calculated hash should be copied back.
214 Contains the key to be used with the algorithm.
216 Contains an explicit initialization vector (IV), if it does not prefix
218 This field is ignored during initialization
219 .Pq Nm crypto_newsession .
220 If no IV is explicitly passed (see below on details), a random IV is used
221 by the device driver processing the request.
223 Contains a pointer to another
226 Multiple such structures may be linked to establish multi-algorithm sessions
228 is an example consumer of such a feature).
233 structure and its contents will not be modified by the framework (or
235 Subsequent requests for processing that use the
236 SID returned will avoid the cost of re-initializing the hardware (in
237 essence, SID acts as an index in the session cache of the driver).
239 .Fn crypto_freesession
240 is called with the SID returned by
241 .Fn crypto_newsession
242 to disestablish the session.
245 is called to process a request.
246 The various fields in the
249 .Bl -tag -width ".Va crp_callback"
253 Indicates the total length in bytes of the buffer to be processed.
255 On return, contains the total length of the result.
256 For symmetric crypto operations, this will be the same as the input length.
257 This will be used if the framework needs to allocate a new
258 buffer for the result (or for re-formatting the input).
260 This routine is invoked upon completion of the request, whether
262 It is invoked through the
265 If the request was not successful, an error code is set in the
268 It is the responsibility of the callback routine to set the appropriate
272 Contains the error type, if any errors were encountered, or zero if
273 the request was successfully processed.
276 error code is returned, the SID has changed (and has been recorded in the
279 The consumer should record the new SID and use it in all subsequent requests.
280 In this case, the request may be re-submitted immediately.
281 This mechanism is used by the framework to perform
282 session migration (move a session from one driver to another, because
283 of availability, performance, or other considerations).
285 Note that this field only makes sense when examined by
286 the callback routine specified in
288 Errors are returned to the invoker of
290 only when enough information is not present to call the callback
291 routine (i.e., if the pointer passed is
293 or if no callback routine was specified).
295 Is a bitmask of flags associated with this request.
296 Currently defined flags are:
297 .Bl -tag -width ".Dv CRYPTO_F_CBIFSYNC"
298 .It Dv CRYPTO_F_IMBUF
299 The buffer pointed to by
303 The buffer pointed to by
308 .It Dv CRYPTO_F_BATCH
309 Batch operation if possible.
310 .It Dv CRYPTO_F_CBIMM
311 Do callback immediately instead of doing it from a dedicated kernel thread.
314 .It Dv CRYPTO_F_CBIFSYNC
315 Do callback immediately if operation is synchronous.
318 Points to the input buffer.
319 On return (when the callback is invoked),
320 it contains the result of the request.
321 The input buffer may be an mbuf
322 chain or a contiguous buffer,
326 This is passed through the crypto framework untouched and is
327 intended for the invoking application's use.
329 This is a linked list of descriptors.
330 Each descriptor provides
331 information about what type of cryptographic operation should be done
333 The various fields are:
334 .Bl -tag -width ".Va crd_inject"
337 .Dv CRD_F_IV_EXPLICIT
338 is set, this field contains the IV.
341 .Dv CRD_F_KEY_EXPLICIT
344 points to a buffer with encryption or authentication key.
347 Must be the same as the one given at newsession time.
353 The offset in the input buffer where processing should start.
355 How many bytes, after
359 Offset from the beginning of the buffer to insert any results.
360 For encryption algorithms, this is where the initialization vector
361 (IV) will be inserted when encrypting or where it can be found when
362 decrypting (subject to
364 For MAC algorithms, this is where the result of the keyed hash will be
367 The following flags are defined:
370 For encryption algorithms, this bit is set when encryption is required
371 (when not set, decryption is performed).
372 .It Dv CRD_F_IV_PRESENT
373 .\" This flag name has nothing to do w/ it's behavior, fix the name.
374 For encryption, if this bit is not set the IV used to encrypt the packet
375 will be written at the location pointed to by
377 The IV length is assumed to be equal to the blocksize of the
378 encryption algorithm.
379 For encryption, if this bit is set, nothing is done.
380 For decryption, this flag has no meaning.
381 Applications that do special
383 such as the half-IV mode in
385 can use this flag to indicate that the IV should not be written on the packet.
386 This flag is typically used in conjunction with the
387 .Dv CRD_F_IV_EXPLICIT
389 .It Dv CRD_F_IV_EXPLICIT
390 This bit is set when the IV is explicitly
391 provided by the consumer in the
394 Otherwise, for encryption operations the IV is provided for by
395 the driver used to perform the operation, whereas for decryption
396 operations it is pointed to by the
399 This flag is typically used when the IV is calculated
401 by the consumer, and does not precede the data (some
403 configurations, and the encrypted swap are two such examples).
404 .It Dv CRD_F_KEY_EXPLICIT
405 For encryption and authentication (MAC) algorithms, this bit is set when the key
406 is explicitly provided by the consumer in the
408 field for the given operation.
409 Otherwise, the key is taken at newsession time from the
412 As calculating the key schedule may take a while, it is recommended that often
413 used keys are given their own session.
415 For compression algorithms, this bit is set when compression is required (when
416 not set, decompression is performed).
421 structure will not be modified by the framework or the device drivers.
422 Since this information accompanies every cryptographic
423 operation request, drivers may re-initialize state on-demand
424 (typically an expensive operation).
425 Furthermore, the cryptographic
426 framework may re-route requests as a result of full queues or hardware
427 failure, as described above.
429 Point to the next descriptor.
430 Linked operations are useful in protocols such as
432 where multiple cryptographic transforms may be applied on the same
440 structure with a linked list of as many
442 structures as were specified in the argument passed to it.
445 deallocates a structure
449 structures linked to it.
450 Note that it is the responsibility of the
451 callback routine to do the necessary cleanups associated with the
457 is called to perform a keying operation.
458 The various fields in the
461 .Bl -tag -width ".Va krp_callback"
463 Operation code, such as
469 variable indicates whether lower level reasons
470 for operation failure.
472 Number if input parameters to the specified operation.
473 Note that each operation has a (typically hardwired) number of such parameters.
475 Number if output parameters from the specified operation.
476 Note that each operation has a (typically hardwired) number of such parameters.
478 An array of kernel memory blocks containing the parameters.
480 Identifier specifying which low-level driver is being used.
482 Callback called on completion of a keying operation.
486 .Fn crypto_get_driverid ,
487 .Fn crypto_register ,
488 .Fn crypto_kregister ,
489 .Fn crypto_unregister ,
493 routines are used by drivers that provide support for cryptographic
494 primitives to register and unregister with the kernel crypto services
496 Drivers must first use the
497 .Fn crypto_get_driverid
498 function to acquire a driver identifier, specifying the
500 as an argument (normally 0, but software-only drivers should specify
501 .Dv CRYPTOCAP_F_SOFTWARE ) .
502 For each algorithm the driver supports, it must then call
503 .Fn crypto_register .
504 The first two arguments are the driver and algorithm identifiers.
505 The next two arguments specify the largest possible operator length (in bits,
506 important for public key operations) and flags for this algorithm.
507 The last four arguments must be provided in the first call to
509 and are ignored in all subsequent calls.
510 They are pointers to three
511 driver-provided functions that the framework may call to establish new
512 cryptographic context with the driver, free already established
513 context, and ask for a request to be processed (encrypt, decrypt,
514 etc.); and an opaque parameter to pass when calling each of these routines.
515 .Fn crypto_unregister
516 is called by drivers that wish to withdraw support for an algorithm.
517 The two arguments are the driver and algorithm identifiers, respectively.
518 Typically, drivers for
520 crypto cards that are being ejected will invoke this routine for all
521 algorithms supported by the card.
522 .Fn crypto_unregister_all
523 will unregister all algorithms registered by a driver
524 and the driver will be disabled (no new sessions will be allocated on
525 that driver, and any existing sessions will be migrated to other
527 The same will be done if all algorithms associated with a driver are
528 unregistered one by one.
530 The calling convention for the three driver-supplied routines is:
535 .Fn \*[lp]*newsession\*[rp] "void *" "uint32_t *" "struct cryptoini *" ;
538 .Fn \*[lp]*freesession\*[rp] "void *" "uint64_t" ;
541 .Fn \*[lp]*process\*[rp] "void *" "struct cryptop *" ;
544 .Fn \*[lp]*kprocess\*[rp] "void *" "struct cryptkop *" ;
547 On invocation, the first argument to
548 all routines is an opaque data value supplied when the algorithm
550 .Fn crypto_register .
551 The second argument to
553 contains the driver identifier obtained via
554 .Fn crypto_get_driverid .
555 On successful return, it should contain a driver-specific session
557 The third argument is identical to that of
558 .Fn crypto_newsession .
562 routine takes as arguments the opaque data value and the SID
563 (which is the concatenation of the
564 driver identifier and the driver-specific session identifier).
565 It should clear any context associated with the session (clear hardware
566 registers, memory, etc.).
570 routine is invoked with a request to perform crypto processing.
571 This routine must not block, but should queue the request and return
573 Upon processing the request, the callback routine should be invoked.
574 In case of an unrecoverable error, the error indication must be placed in the
579 When the request is completed, or an error is detected, the
581 routine should invoke
583 Session migration may be performed, as mentioned previously.
585 In case of a temporary resource exhaustion, the
589 in which case the crypto services will requeue the request, mark the driver
592 and stop submitting requests for processing.
593 The driver is then responsible for notifying the crypto services
594 when it is again able to process requests through the
597 This simple flow control mechanism should only be used for short-lived
598 resource exhaustion as it causes operations to be queued in the crypto
600 Doing so is preferable to returning an error in such cases as
601 it can cause network protocols to degrade performance by treating the
602 failure much like a lost packet.
606 routine is invoked with a request to perform crypto key processing.
607 This routine must not block, but should queue the request and return
609 Upon processing the request, the callback routine should be invoked.
610 In case of an unrecoverable error, the error indication must be placed in the
615 When the request is completed, or an error is detected, the
617 routine should invoked
620 .Fn crypto_register ,
621 .Fn crypto_kregister ,
622 .Fn crypto_unregister ,
623 .Fn crypto_newsession ,
624 .Fn crypto_freesession ,
627 return 0 on success, or an error code on failure.
628 .Fn crypto_get_driverid
629 returns a non-negative value on error, and \-1 on failure.
631 returns a pointer to a
639 if its argument or the callback function was
642 The callback is provided with an error code in case of failure, in the
646 .Bl -tag -width ".Pa sys/opencrypto/crypto.c"
647 .It Pa sys/opencrypto/crypto.c
648 most of the framework code
657 The cryptographic framework first appeared in
660 .An Angelos D. Keromytis Aq Mt angelos@openbsd.org .
662 The framework currently assumes that all the algorithms in a
663 .Fn crypto_newsession
664 operation must be available by the same driver.
665 If that is not the case, session initialization will fail.
667 The framework also needs a mechanism for determining which driver is
668 best for a specific set of algorithms associated with a session.
669 Some type of benchmarking is in order here.
671 Multiple instances of the same algorithm in the same session are not
673 Note that 3DES is considered one algorithm (and not three
675 Thus, 3DES and DES could be mixed in the same request.