diff options
Diffstat (limited to 'share/man/man9/crypto.9')
| -rw-r--r-- | share/man/man9/crypto.9 | 666 |
1 files changed, 666 insertions, 0 deletions
diff --git a/share/man/man9/crypto.9 b/share/man/man9/crypto.9 new file mode 100644 index 0000000..8ed30d9 --- /dev/null +++ b/share/man/man9/crypto.9 @@ -0,0 +1,666 @@ +.\" $OpenBSD: crypto.9,v 1.19 2002/07/16 06:31:57 angelos Exp $ +.\" +.\" The author of this manual page is Angelos D. Keromytis (angelos@cis.upenn.edu) +.\" +.\" Copyright (c) 2000, 2001 Angelos D. Keromytis +.\" +.\" Permission to use, copy, and modify this software with or without fee +.\" is hereby granted, provided that this entire notice is included in +.\" all source code copies of any software which is or includes a copy or +.\" modification of this software. +.\" +.\" THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR +.\" IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY +.\" REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE +.\" MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR +.\" PURPOSE. +.\" +.\" $FreeBSD$ +.\" +.Dd April 18, 2014 +.Dt CRYPTO 9 +.Os +.Sh NAME +.Nm crypto +.Nd API for cryptographic services in the kernel +.Sh SYNOPSIS +.In opencrypto/cryptodev.h +.Ft int32_t +.Fn crypto_get_driverid uint8_t +.Ft int +.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 *" +.Ft int +.Fn crypto_kregister uint32_t int uint32_t "int \*[lp]*\*[rp]\*[lp]void *, struct cryptkop *\*[rp]" "void *" +.Ft int +.Fn crypto_unregister uint32_t int +.Ft int +.Fn crypto_unregister_all uint32_t +.Ft void +.Fn crypto_done "struct cryptop *" +.Ft void +.Fn crypto_kdone "struct cryptkop *" +.Ft int +.Fn crypto_newsession "uint64_t *" "struct cryptoini *" int +.Ft int +.Fn crypto_freesession uint64_t +.Ft int +.Fn crypto_dispatch "struct cryptop *" +.Ft int +.Fn crypto_kdispatch "struct cryptkop *" +.Ft int +.Fn crypto_unblock uint32_t int +.Ft "struct cryptop *" +.Fn crypto_getreq int +.Ft void +.Fn crypto_freereq void +.Bd -literal +#define CRYPTO_SYMQ 0x1 +#define CRYPTO_ASYMQ 0x2 + +#define EALG_MAX_BLOCK_LEN 16 + +struct cryptoini { + int cri_alg; + int cri_klen; + int cri_mlen; + caddr_t cri_key; + uint8_t cri_iv[EALG_MAX_BLOCK_LEN]; + struct cryptoini *cri_next; +}; + +struct cryptodesc { + int crd_skip; + int crd_len; + int crd_inject; + int crd_flags; + struct cryptoini CRD_INI; +#define crd_iv CRD_INI.cri_iv +#define crd_key CRD_INI.cri_key +#define crd_alg CRD_INI.cri_alg +#define crd_klen CRD_INI.cri_klen + struct cryptodesc *crd_next; +}; + +struct cryptop { + TAILQ_ENTRY(cryptop) crp_next; + uint64_t crp_sid; + int crp_ilen; + int crp_olen; + int crp_etype; + int crp_flags; + caddr_t crp_buf; + caddr_t crp_opaque; + struct cryptodesc *crp_desc; + int (*crp_callback) (struct cryptop *); + caddr_t crp_mac; +}; + +struct crparam { + caddr_t crp_p; + u_int crp_nbits; +}; + +#define CRK_MAXPARAM 8 + +struct cryptkop { + TAILQ_ENTRY(cryptkop) krp_next; + u_int krp_op; /* ie. CRK_MOD_EXP or other */ + u_int krp_status; /* return status */ + u_short krp_iparams; /* # of input parameters */ + u_short krp_oparams; /* # of output parameters */ + uint32_t krp_hid; + struct crparam krp_param[CRK_MAXPARAM]; + int (*krp_callback)(struct cryptkop *); +}; +.Ed +.Sh DESCRIPTION +.Nm +is a framework for drivers of cryptographic hardware to register with +the kernel so +.Dq consumers +(other kernel subsystems, and +users through the +.Pa /dev/crypto +device) are able to make use of it. +Drivers register with the framework the algorithms they support, +and provide entry points (functions) the framework may call to +establish, use, and tear down sessions. +Sessions are used to cache cryptographic information in a particular driver +(or associated hardware), so initialization is not needed with every request. +Consumers of cryptographic services pass a set of +descriptors that instruct the framework (and the drivers registered +with it) of the operations that should be applied on the data (more +than one cryptographic operation can be requested). +.Pp +Keying operations are supported as well. +Unlike the symmetric operators described above, +these sessionless commands perform mathematical operations using +input and output parameters. +.Pp +Since the consumers may not be associated with a process, drivers may +not +.Xr sleep 9 . +The same holds for the framework. +Thus, a callback mechanism is used +to notify a consumer that a request has been completed (the +callback is specified by the consumer on a per-request basis). +The callback is invoked by the framework whether the request was +successfully completed or not. +An error indication is provided in the latter case. +A specific error code, +.Er EAGAIN , +is used to indicate that a session number has changed and that the +request may be re-submitted immediately with the new session number. +Errors are only returned to the invoking function if not +enough information to call the callback is available (meaning, there +was a fatal error in verifying the arguments). +For session initialization and teardown there is no callback mechanism used. +.Pp +The +.Fn crypto_newsession +routine is called by consumers of cryptographic services (such as the +.Xr ipsec 4 +stack) that wish to establish a new session with the framework. +On success, the first argument will contain the Session Identifier (SID). +The second argument contains all the necessary information for +the driver to establish the session. +The third argument indicates whether a +hardware driver (1) should be used or not (0). +The various fields in the +.Vt cryptoini +structure are: +.Bl -tag -width ".Va cri_next" +.It Va cri_alg +Contains an algorithm identifier. +Currently supported algorithms are: +.Pp +.Bl -tag -width ".Dv CRYPTO_RIPEMD160_HMAC" -compact +.It Dv CRYPTO_AES_CBC +.It Dv CRYPTO_ARC4 +.It Dv CRYPTO_BLF_CBC +.It Dv CRYPTO_CAMELLIA_CBC +.It Dv CRYPTO_CAST_CBC +.It Dv CRYPTO_DES_CBC +.It Dv CRYPTO_3DES_CBC +.It Dv CRYPTO_SKIPJACK_CBC +.It Dv CRYPTO_MD5 +.It Dv CRYPTO_MD5_HMAC +.It Dv CRYPTO_MD5_KPDK +.It Dv CRYPTO_RIPEMD160_HMAC +.It Dv CRYPTO_SHA1 +.It Dv CRYPTO_SHA1_HMAC +.It Dv CRYPTO_SHA1_KPDK +.It Dv CRYPTO_SHA2_256_HMAC +.It Dv CRYPTO_SHA2_384_HMAC +.It Dv CRYPTO_SHA2_512_HMAC +.It Dv CRYPTO_NULL_HMAC +.It Dv CRYPTO_NULL_CBC +.El +.It Va cri_klen +Specifies the length of the key in bits, for variable-size key +algorithms. +.It Va cri_mlen +Specifies how many bytes from the calculated hash should be copied back. +0 means entire hash. +.It Va cri_key +Contains the key to be used with the algorithm. +.It Va cri_iv +Contains an explicit initialization vector (IV), if it does not prefix +the data. +This field is ignored during initialization. +If no IV is explicitly passed (see below on details), a random IV is used +by the device driver processing the request. +.It Va cri_next +Contains a pointer to another +.Vt cryptoini +structure. +Multiple such structures may be linked to establish multi-algorithm sessions +.Xr ( ipsec 4 +is an example consumer of such a feature). +.El +.Pp +The +.Vt cryptoini +structure and its contents will not be modified by the framework (or +the drivers used). +Subsequent requests for processing that use the +SID returned will avoid the cost of re-initializing the hardware (in +essence, SID acts as an index in the session cache of the driver). +.Pp +.Fn crypto_freesession +is called with the SID returned by +.Fn crypto_newsession +to disestablish the session. +.Pp +.Fn crypto_dispatch +is called to process a request. +The various fields in the +.Vt cryptop +structure are: +.Bl -tag -width ".Va crp_callback" +.It Va crp_sid +Contains the SID. +.It Va crp_ilen +Indicates the total length in bytes of the buffer to be processed. +.It Va crp_olen +On return, contains the total length of the result. +For symmetric crypto operations, this will be the same as the input length. +This will be used if the framework needs to allocate a new +buffer for the result (or for re-formatting the input). +.It Va crp_callback +This routine is invoked upon completion of the request, whether +successful or not. +It is invoked through the +.Fn crypto_done +routine. +If the request was not successful, an error code is set in the +.Va crp_etype +field. +It is the responsibility of the callback routine to set the appropriate +.Xr spl 9 +level. +.It Va crp_etype +Contains the error type, if any errors were encountered, or zero if +the request was successfully processed. +If the +.Er EAGAIN +error code is returned, the SID has changed (and has been recorded in the +.Va crp_sid +field). +The consumer should record the new SID and use it in all subsequent requests. +In this case, the request may be re-submitted immediately. +This mechanism is used by the framework to perform +session migration (move a session from one driver to another, because +of availability, performance, or other considerations). +.Pp +Note that this field only makes sense when examined by +the callback routine specified in +.Va crp_callback . +Errors are returned to the invoker of +.Fn crypto_process +only when enough information is not present to call the callback +routine (i.e., if the pointer passed is +.Dv NULL +or if no callback routine was specified). +.It Va crp_flags +Is a bitmask of flags associated with this request. +Currently defined flags are: +.Bl -tag -width ".Dv CRYPTO_F_CBIFSYNC" +.It Dv CRYPTO_F_IMBUF +The buffer pointed to by +.Va crp_buf +is an mbuf chain. +.It Dv CRYPTO_F_IOV +The buffer pointed to by +.Va crp_buf +is an +.Vt uio +structure. +.It Dv CRYPTO_F_REL +Must return data in the same place. +.It Dv CRYPTO_F_BATCH +Batch operation if possible. +.It Dv CRYPTO_F_CBIMM +Do callback immediately instead of doing it from a dedicated kernel thread. +.It Dv CRYPTO_F_DONE +Operation completed. +.It Dv CRYPTO_F_CBIFSYNC +Do callback immediately if operation is synchronous. +.El +.It Va crp_buf +Points to the input buffer. +On return (when the callback is invoked), +it contains the result of the request. +The input buffer may be an mbuf +chain or a contiguous buffer, +depending on +.Va crp_flags . +.It Va crp_opaque +This is passed through the crypto framework untouched and is +intended for the invoking application's use. +.It Va crp_desc +This is a linked list of descriptors. +Each descriptor provides +information about what type of cryptographic operation should be done +on the input buffer. +The various fields are: +.Bl -tag -width ".Va crd_inject" +.It Va crd_iv +The field where IV should be provided when the +.Dv CRD_F_IV_EXPLICIT +flag is given. +.It Va crd_key +When the +.Dv CRD_F_KEY_EXPLICIT +flag is given, the +.Va crd_key +points to a buffer with encryption or authentication key. +.It Va crd_alg +An algorithm to use. +Must be the same as the one given at newsession time. +.It Va crd_klen +The +.Va crd_key +key length. +.It Va crd_skip +The offset in the input buffer where processing should start. +.It Va crd_len +How many bytes, after +.Va crd_skip , +should be processed. +.It Va crd_inject +Offset from the beginning of the buffer to insert any results. +For encryption algorithms, this is where the initialization vector +(IV) will be inserted when encrypting or where it can be found when +decrypting (subject to +.Va crd_flags ) . +For MAC algorithms, this is where the result of the keyed hash will be +inserted. +.It Va crd_flags +The following flags are defined: +.Bl -tag -width 3n +.It Dv CRD_F_ENCRYPT +For encryption algorithms, this bit is set when encryption is required +(when not set, decryption is performed). +.It Dv CRD_F_IV_PRESENT +For encryption algorithms, this bit is set when the IV already +precedes the data, so the +.Va crd_inject +value will be ignored and no IV will be written in the buffer. +Otherwise, the IV used to encrypt the packet will be written +at the location pointed to by +.Va crd_inject . +The IV length is assumed to be equal to the blocksize of the +encryption algorithm. +Some applications that do special +.Dq "IV cooking" , +such as the half-IV mode in +.Xr ipsec 4 , +can use this flag to indicate that the IV should not be written on the packet. +This flag is typically used in conjunction with the +.Dv CRD_F_IV_EXPLICIT +flag. +.It Dv CRD_F_IV_EXPLICIT +For encryption algorithms, this bit is set when the IV is explicitly +provided by the consumer in the +.Va crd_iv +field. +Otherwise, for encryption operations the IV is provided for by +the driver used to perform the operation, whereas for decryption +operations it is pointed to by the +.Va crd_inject +field. +This flag is typically used when the IV is calculated +.Dq "on the fly" +by the consumer, and does not precede the data (some +.Xr ipsec 4 +configurations, and the encrypted swap are two such examples). +.It Dv CRD_F_KEY_EXPLICIT +For encryption and authentication (MAC) algorithms, this bit is set when the key +is explicitly provided by the consumer in the +.Va crd_key +field for the given operation. +Otherwise, the key is taken at newsession time from the +.Va cri_key +field. +.It Dv CRD_F_COMP +For compression algorithms, this bit is set when compression is required (when +not set, decompression is performed). +.El +.It Va CRD_INI +This +.Vt cryptoini +structure will not be modified by the framework or the device drivers. +Since this information accompanies every cryptographic +operation request, drivers may re-initialize state on-demand +(typically an expensive operation). +Furthermore, the cryptographic +framework may re-route requests as a result of full queues or hardware +failure, as described above. +.It Va crd_next +Point to the next descriptor. +Linked operations are useful in protocols such as +.Xr ipsec 4 , +where multiple cryptographic transforms may be applied on the same +block of data. +.El +.El +.Pp +.Fn crypto_getreq +allocates a +.Vt cryptop +structure with a linked list of as many +.Vt cryptodesc +structures as were specified in the argument passed to it. +.Pp +.Fn crypto_freereq +deallocates a structure +.Vt cryptop +and any +.Vt cryptodesc +structures linked to it. +Note that it is the responsibility of the +callback routine to do the necessary cleanups associated with the +opaque field in the +.Vt cryptop +structure. +.Pp +.Fn crypto_kdispatch +is called to perform a keying operation. +The various fields in the +.Vt cryptkop +structure are: +.Bl -tag -width ".Va krp_callback" +.It Va krp_op +Operation code, such as +.Dv CRK_MOD_EXP . +.It Va krp_status +Return code. +This +.Va errno Ns -style +variable indicates whether lower level reasons +for operation failure. +.It Va krp_iparams +Number if input parameters to the specified operation. +Note that each operation has a (typically hardwired) number of such parameters. +.It Va krp_oparams +Number if output parameters from the specified operation. +Note that each operation has a (typically hardwired) number of such parameters. +.It Va krp_kvp +An array of kernel memory blocks containing the parameters. +.It Va krp_hid +Identifier specifying which low-level driver is being used. +.It Va krp_callback +Callback called on completion of a keying operation. +.El +.Sh DRIVER-SIDE API +The +.Fn crypto_get_driverid , +.Fn crypto_register , +.Fn crypto_kregister , +.Fn crypto_unregister , +.Fn crypto_unblock , +and +.Fn crypto_done +routines are used by drivers that provide support for cryptographic +primitives to register and unregister with the kernel crypto services +framework. +Drivers must first use the +.Fn crypto_get_driverid +function to acquire a driver identifier, specifying the +.Fa cc_flags +as an argument (normally 0, but software-only drivers should specify +.Dv CRYPTOCAP_F_SOFTWARE ) . +For each algorithm the driver supports, it must then call +.Fn crypto_register . +The first two arguments are the driver and algorithm identifiers. +The next two arguments specify the largest possible operator length (in bits, +important for public key operations) and flags for this algorithm. +The last four arguments must be provided in the first call to +.Fn crypto_register +and are ignored in all subsequent calls. +They are pointers to three +driver-provided functions that the framework may call to establish new +cryptographic context with the driver, free already established +context, and ask for a request to be processed (encrypt, decrypt, +etc.); and an opaque parameter to pass when calling each of these routines. +.Fn crypto_unregister +is called by drivers that wish to withdraw support for an algorithm. +The two arguments are the driver and algorithm identifiers, respectively. +Typically, drivers for +PCMCIA +crypto cards that are being ejected will invoke this routine for all +algorithms supported by the card. +.Fn crypto_unregister_all +will unregister all algorithms registered by a driver +and the driver will be disabled (no new sessions will be allocated on +that driver, and any existing sessions will be migrated to other +drivers). +The same will be done if all algorithms associated with a driver are +unregistered one by one. +.Pp +The calling convention for the three driver-supplied routines is: +.Pp +.Bl -item -compact +.It +.Ft int +.Fn \*[lp]*newsession\*[rp] "void *" "uint32_t *" "struct cryptoini *" ; +.It +.Ft int +.Fn \*[lp]*freesession\*[rp] "void *" "uint64_t" ; +.It +.Ft int +.Fn \*[lp]*process\*[rp] "void *" "struct cryptop *" ; +.It +.Ft int +.Fn \*[lp]*kprocess\*[rp] "void *" "struct cryptkop *" ; +.El +.Pp +On invocation, the first argument to +all routines is an opaque data value supplied when the algorithm +is registered with +.Fn crypto_register . +The second argument to +.Fn newsession +contains the driver identifier obtained via +.Fn crypto_get_driverid . +On successful return, it should contain a driver-specific session +identifier. +The third argument is identical to that of +.Fn crypto_newsession . +.Pp +The +.Fn freesession +routine takes as arguments the opaque data value and the SID +(which is the concatenation of the +driver identifier and the driver-specific session identifier). +It should clear any context associated with the session (clear hardware +registers, memory, etc.). +.Pp +The +.Fn process +routine is invoked with a request to perform crypto processing. +This routine must not block, but should queue the request and return +immediately. +Upon processing the request, the callback routine should be invoked. +In case of an unrecoverable error, the error indication must be placed in the +.Va crp_etype +field of the +.Vt cryptop +structure. +When the request is completed, or an error is detected, the +.Fn process +routine should invoke +.Fn crypto_done . +Session migration may be performed, as mentioned previously. +.Pp +In case of a temporary resource exhaustion, the +.Fn process +routine may return +.Er ERESTART +in which case the crypto services will requeue the request, mark the driver +as +.Dq blocked , +and stop submitting requests for processing. +The driver is then responsible for notifying the crypto services +when it is again able to process requests through the +.Fn crypto_unblock +routine. +This simple flow control mechanism should only be used for short-lived +resource exhaustion as it causes operations to be queued in the crypto +layer. +Doing so is preferable to returning an error in such cases as +it can cause network protocols to degrade performance by treating the +failure much like a lost packet. +.Pp +The +.Fn kprocess +routine is invoked with a request to perform crypto key processing. +This routine must not block, but should queue the request and return +immediately. +Upon processing the request, the callback routine should be invoked. +In case of an unrecoverable error, the error indication must be placed in the +.Va krp_status +field of the +.Vt cryptkop +structure. +When the request is completed, or an error is detected, the +.Fn kprocess +routine should invoked +.Fn crypto_kdone . +.Sh RETURN VALUES +.Fn crypto_register , +.Fn crypto_kregister , +.Fn crypto_unregister , +.Fn crypto_newsession , +.Fn crypto_freesession , +and +.Fn crypto_unblock +return 0 on success, or an error code on failure. +.Fn crypto_get_driverid +returns a non-negative value on error, and \-1 on failure. +.Fn crypto_getreq +returns a pointer to a +.Vt cryptop +structure and +.Dv NULL +on failure. +.Fn crypto_dispatch +returns +.Er EINVAL +if its argument or the callback function was +.Dv NULL , +and 0 otherwise. +The callback is provided with an error code in case of failure, in the +.Va crp_etype +field. +.Sh FILES +.Bl -tag -width ".Pa sys/opencrypto/crypto.c" +.It Pa sys/opencrypto/crypto.c +most of the framework code +.El +.Sh SEE ALSO +.Xr crypto 4 , +.Xr ipsec 4 , +.Xr malloc 9 , +.Xr sleep 9 +.Sh HISTORY +The cryptographic framework first appeared in +.Ox 2.7 +and was written by +.An Angelos D. Keromytis Aq Mt angelos@openbsd.org . +.Sh BUGS +The framework currently assumes that all the algorithms in a +.Fn crypto_newsession +operation must be available by the same driver. +If that is not the case, session initialization will fail. +.Pp +The framework also needs a mechanism for determining which driver is +best for a specific set of algorithms associated with a session. +Some type of benchmarking is in order here. +.Pp +Multiple instances of the same algorithm in the same session are not +supported. +Note that 3DES is considered one algorithm (and not three +instances of DES). +Thus, 3DES and DES could be mixed in the same request. |
