<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd">
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<refentry id="crypto9">
<refmeta>
<refentrytitle>CRYPTO</refentrytitle>
<manvolnum>9</manvolnum>
</refmeta>
<refnamediv id="purpose">
<refname>crypto</refname>
<refpurpose>API for cryptographic services in the kernel</refpurpose>
</refnamediv>
<literallayout remap="Bd"><funcsynopsis><funcsynopsisinfo>
#define CRYPTO_SYMQ 0x1
#define CRYPTO_ASYMQ 0x2
#define EALG_MAX_BLOCK_LEN 16
struct cryptoini { int cri_alg;
int cri_klen;
int cri_rnd;
caddr_t cri_key;
u_int8_t cri_iv[EALG_MAX_BLOCK_LEN];
struct cryptoini *cri_next;
}; </funcsynopsisinfo><funcsynopsisinfo>struct cryptodesc { int crd_skip;
int crd_len;
int crd_inject;
int crd_flags;
struct cryptoini CRD_INI;
struct cryptodesc *crd_next;
}; </funcsynopsisinfo><funcsynopsisinfo>struct cryptop { TAILQ_ENTRY(cryptop) crp_next;
u_int64_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;
}; </funcsynopsisinfo><funcsynopsisinfo>struct crparam { caddr_t crp_p;
u_int crp_nbits;
}; </funcsynopsisinfo><funcsynopsisinfo>
#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 */
u_int32_t krp_hid;
struct crparam krp_param[CRK_MAXPARAM];
int (*krp_callback)(struct cryptkop *);
}; </funcsynopsisinfo></funcsynopsis></literallayout>
<!---->
<para><command remap="Nm">crypto </command> is a framework for drivers of
cryptographic hardware to register with the kernel so “consumers” (other
kernel subsystems, and users through the
<replaceable>/dev/crypto</replaceable> 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).</para>
<sbr />
Keying operations are supported as well. Unlike the symmetric operators described above, these sessionless commands perform mathematical operations using input and output parameters.
<sbr />
Since the consumers may not be associated with a process, drivers may not
<citerefentry>
<refentrytitle>sleep</refentrytitle>
<manvolnum>9</manvolnum>
</citerefentry>
. 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 an 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,
<errorcode>EAGAIN</errorcode>
, 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.
<sbr />
The crypto_newsession(); routine is called by consumers of cryptographic services (such as the
<citerefentry>
<refentrytitle>ipsec</refentrytitle>
<manvolnum>4</manvolnum>
</citerefentry>
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
<vartype>cryptoini</vartype>
structure are:
<variablelist remap="Bl -tag -width .Va cri_next">
<varlistentry>
<term>
<varname>cri_alg</varname>
</term>
<listitem>
<para>Contains an algorithm identifier. Currently supported algorithms
are:</para>
<sbr />
<table remap="Bl -tag -width .Dv CRYPTO_RIPEMD160_HMAC -compact">
<title />
<tgroup cols="1">
<tbody>
<row>
<entry>
<constant>CRYPTO_DES_CBC</constant>
</entry>
</row>
<row>
<entry>
<constant>CRYPTO_3DES_CBC</constant>
</entry>
</row>
<row>
<entry>
<constant>CRYPTO_BLF_CBC</constant>
</entry>
</row>
<row>
<entry>
<constant>CRYPTO_CAST_CBC</constant>
</entry>
</row>
<row>
<entry>
<constant>CRYPTO_SKIPJACK_CBC</constant>
</entry>
</row>
<row>
<entry>
<constant>CRYPTO_MD5_HMAC</constant>
</entry>
</row>
<row>
<entry>
<constant>CRYPTO_SHA1_HMAC</constant>
</entry>
</row>
<row>
<entry>
<constant>CRYPTO_RIPEMD160_HMAC</constant>
</entry>
</row>
<row>
<entry>
<constant>CRYPTO_MD5_KPDK</constant>
</entry>
</row>
<row>
<entry>
<constant>CRYPTO_SHA1_KPDK</constant>
</entry>
</row>
<row>
<entry>
<constant>CRYPTO_AES_CBC</constant>
</entry>
</row>
<row>
<entry>
<constant>CRYPTO_ARC4</constant>
</entry>
</row>
<row>
<entry>
<constant>CRYPTO_MD5</constant>
</entry>
</row>
<row>
<entry>
<constant>CRYPTO_SHA1</constant>
</entry>
</row>
<row>
<entry>
<constant>CRYPTO_SHA2_HMAC</constant>
</entry>
</row>
<row>
<entry>
<constant>CRYPTO_NULL_HMAC</constant>
</entry>
</row>
<row>
<entry>
<constant>CRYPTO_NULL_CBC</constant>
</entry>
</row>
</tbody>
</tgroup>
</table>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>cri_klen</varname>
</term>
<listitem>
<para>Specifies the length of the key in bits, for variable-size key
algorithms.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>cri_rnd</varname>
</term>
<listitem>
<para>Specifies the number of rounds to be used with the algorithm,
for variable-round algorithms.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>cri_key</varname>
</term>
<listitem>
<para>Contains the key to be used with the algorithm.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>cri_iv</varname>
</term>
<listitem>
<para>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.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>cri_next</varname>
</term>
<listitem><para>Contains a pointer to another</para>
<vartype>cryptoini</vartype> structure. Multiple such structures may be
linked to establish multi-algorithm sessions (<citerefentry>
<refentrytitle>ipsec</refentrytitle>
<manvolnum>4</manvolnum>
</citerefentry> is an example consumer of such a feature).</listitem>
</varlistentry>
</variablelist>
<sbr />
<para>The</para>
<vartype>cryptoini</vartype>
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).
<sbr />
crypto_freesession(); is called with the SID returned by crypto_newsession(); to disestablish the session.
<sbr />
crypto_dispatch(); is called to process a request. The various fields in the
<vartype>cryptop</vartype>
structure are:
<variablelist remap="Bl -tag -width .Va crp_callback">
<varlistentry>
<term>
<varname>crp_sid</varname>
</term>
<listitem>
<para>Contains the SID.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>crp_ilen</varname>
</term>
<listitem>
<para>Indicates the total length in bytes of the buffer to be
processed.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>crp_olen</varname>
</term>
<listitem>
<para>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).</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>crp_callback</varname>
</term>
<listitem>
<para>This routine is invoked upon completion of the request, whether
successful or not. It is invoked through the crypto_done(); routine.
If the request was not successful, an error code is set in the
<varname>crp_etype</varname> field. It is the responsibility of the
callback routine to set the appropriate <citerefentry>
<refentrytitle>spl</refentrytitle>
<manvolnum>9</manvolnum>
</citerefentry> level.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>crp_etype</varname>
</term>
<listitem><para>Contains the error type, if any errors were encountered,
or zero if the request was successfully processed. If the
<errorcode>EAGAIN</errorcode> error code is returned, the SID has
changed (and has been recorded in the <varname>crp_sid</varname> 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).</para> <sbr /> Note that this
field only makes sense when examined by the callback routine specified
in <varname>crp_callback</varname>. Errors are returned to the invoker
of crypto_process(); only when enough information is not present to call
the callback routine (i.e., if the pointer passed is
<constant>NULL</constant> or if no callback routine was
specified).</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>crp_flags</varname>
</term>
<listitem>
<para>Is a bitmask of flags associated with this request. Currently
defined flags are:</para>
<variablelist remap="Bl -tag -width .Dv CRYPTO_F_IMBUF">
<varlistentry>
<term>
<constant>CRYPTO_F_IMBUF</constant>
</term>
<listitem>
<para>The buffer pointed to by <varname>crp_buf</varname> is an
mbuf chain.</para>
</listitem>
</varlistentry>
</variablelist>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>crp_buf</varname>
</term>
<listitem>
<para>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
<varname>crp_flags</varname>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>crp_opaque</varname>
</term>
<listitem>
<para>This is passed through the crypto framework untouched and is
intended for the invoking application's use.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>crp_desc</varname>
</term>
<listitem>
<para>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:</para>
<variablelist remap="Bl -tag -width .Va crd_inject">
<varlistentry>
<term>
<varname>crd_skip</varname>
</term>
<listitem>
<para>The offset in the input buffer where processing should
start.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>crd_len</varname>
</term>
<listitem>
<para>How many bytes, after <varname>crd_skip</varname>, should
be processed.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>crd_inject</varname>
</term>
<listitem>
<para>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
<varname>crd_flags</varname>). For MAC algorithms, this is where
the result of the keyed hash will be inserted.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>crd_flags</varname>
</term>
<listitem>
<para>The following flags are defined:</para>
<variablelist remap="Bl -tag -width .Dv CRD_F_IV_EXPLICIT">
<varlistentry>
<term>
<constant>CRD_F_ENCRYPT</constant>
</term>
<listitem>
<para>For encryption algorithms, this bit is set when
encryption is required (when not set, decryption is
performed).</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<constant>CRD_F_IV_PRESENT</constant>
</term>
<listitem>
<para>For encryption algorithms, this bit is set when the
IV already precedes the data, so the
<varname>crd_inject</varname> 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 <varname>crd_inject</varname>. The IV length
is assumed to be equal to the blocksize of the encryption
algorithm. Some applications that do special “IV cooking”,
such as the half-IV mode in <citerefentry>
<refentrytitle>ipsec</refentrytitle>
<manvolnum>4</manvolnum>
</citerefentry>, 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
<constant>CRD_F_IV_EXPLICIT</constant> flag.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<constant>CRD_F_IV_EXPLICIT</constant>
</term>
<listitem>
<para>For encryption algorithms, this bit is set when the
IV is explicitly provided by the consumer in the
<varname>cri_iv</varname> fields. 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
<varname>crd_inject</varname> field. This flag is
typically used when the IV is calculated “on the fly” by
the consumer, and does not precede the data (some
<citerefentry>
<refentrytitle>ipsec</refentrytitle>
<manvolnum>4</manvolnum>
</citerefentry> configurations, and the encrypted swap
are two such examples).</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<constant>CRD_F_COMP</constant>
</term>
<listitem>
<para>For compression algorithms, this bit is set when
compression is required (when not set, decompression is
performed).</para>
</listitem>
</varlistentry>
</variablelist>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>CRD_INI</varname>
</term>
<listitem><para>This</para> <vartype>cryptoini</vartype> 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.</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>crd_next</varname>
</term>
<listitem>
<para>Point to the next descriptor. Linked operations are useful
in protocols such as <citerefentry>
<refentrytitle>ipsec</refentrytitle>
<manvolnum>4</manvolnum>
</citerefentry>, where multiple cryptographic transforms may
be applied on the same block of data.</para>
</listitem>
</varlistentry>
</variablelist>
</listitem>
</varlistentry>
</variablelist>
<sbr />
<para>crypto_getreq(); allocates a</para>
<vartype>cryptop</vartype>
structure with a linked list of as many
<vartype>cryptodesc</vartype>
structures as were specified in the argument passed to it.
<sbr />
crypto_freereq(); deallocates a structure
<vartype>cryptop</vartype>
and any
<vartype>cryptodesc</vartype>
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
<vartype>cryptop</vartype>
structure.
<sbr />
crypto_kdispatch(); is called to perform a keying operation. The various fields in the
<vartype>cryptkop</vartype>
structure are:
<variablelist remap="Bl -tag -width .Va krp_callback">
<varlistentry>
<term>
<varname>krp_op</varname>
</term>
<listitem>
<para>Operation code, such as <constant>CRK_MOD_EXP</constant>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>krp_status</varname>
</term>
<listitem>
<para>Return code. This <varname>errno</varname>-style variable
indicates whether lower level reasons for operation failure.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>krp_iparams</varname>
</term>
<listitem>
<para>Number if input parameters to the specified operation. Note that
each operation has a (typically hardwired) number of such
parameters.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>krp_oparams</varname>
</term>
<listitem>
<para>Number if output parameters from the specified operation. Note
that each operation has a (typically hardwired) number of such
parameters.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>krp_kvp</varname>
</term>
<listitem>
<para>An array of kernel memory blocks containing the
parameters.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>krp_hid</varname>
</term>
<listitem>
<para>Identifier specifying which low-level driver is being
used.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>krp_callback</varname>
</term>
<listitem>
<para>Callback called on completion of a keying operation.</para>
</listitem>
</varlistentry>
</variablelist>
<!-- body begins here -->
<refsynopsisdiv id="synopsis">
<funcsynopsis>
<funcsynopsisinfo>
#include <opencrypto/cryptodev.h>
</funcsynopsisinfo>
<funcprototype>
<funcdef><function>int32_t</function> crypto_get_driverid</funcdef>
<paramdef>
<parameter>u_int8_t</parameter>
</paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>crypto_register</function></funcdef>
<paramdef>
<parameter>u_int32_t</parameter>
</paramdef>
<paramdef>
<parameter>int</parameter>
</paramdef>
<paramdef>
<parameter>u_int16_t</parameter>
</paramdef>
<paramdef>
<parameter>u_int32_t</parameter>
</paramdef>
<paramdef>int (*)(<parameter>void</parameter>*</paramdef>
<paramdef>u_int32_t * <parameter /></paramdef>
<paramdef>struct cryptoini *)<parameter /></paramdef>
<paramdef>int (*)(<parameter>void</parameter>*</paramdef>
<paramdef>u_int64_t )</paramdef>
<paramdef>int (*)(<parameter>void</parameter>*</paramdef>
<paramdef>struct cryptop *)</paramdef>
<paramdef>void * <parameter /></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>crypto_kregister</function></funcdef>
<paramdef>
<parameter>u_int32_t</parameter>
</paramdef>
<paramdef>
<parameter>int</parameter>
</paramdef>
<paramdef>
<parameter>u_int32_t</parameter>
</paramdef>
<paramdef>int (*)(<parameter>void</parameter>*</paramdef>
<paramdef>struct cryptkop *)</paramdef>
<paramdef>void * <parameter /></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>crypto_unregister</function></funcdef>
<paramdef>
<parameter>u_int32_t</parameter>
</paramdef>
<paramdef>
<parameter>int</parameter>
</paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>crypto_unregister_all</function></funcdef>
<paramdef>
<parameter>u_int32_t</parameter>
</paramdef>
</funcprototype>
<funcprototype>
<funcdef>void <function>crypto_done</function></funcdef>
<paramdef>struct <parameter>cryptop</parameter>*</paramdef>
</funcprototype>
<funcprototype>
<funcdef>void <function>crypto_kdone</function></funcdef>
<paramdef>struct <parameter>cryptkop</parameter>*</paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>crypto_newsession</function></funcdef>
<paramdef>u_int64_t * <parameter /></paramdef>
<paramdef>struct <parameter>cryptoini</parameter>*</paramdef>
<paramdef>
<parameter>int</parameter>
</paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>crypto_freesession</function></funcdef>
<paramdef>
<parameter>u_int64_t</parameter>
</paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>crypto_dispatch</function></funcdef>
<paramdef>struct <parameter>cryptop</parameter>*</paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>crypto_kdispatch</function></funcdef>
<paramdef>struct <parameter>cryptkop</parameter>*</paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>crypto_unblock</function></funcdef>
<paramdef>
<parameter>u_int32_t</parameter>
</paramdef>
<paramdef>
<parameter>int</parameter>
</paramdef>
</funcprototype>
<funcprototype>
<funcdef>struct <function>cryptop</function> *crypto_getreq</funcdef>
<paramdef>
<parameter>int</parameter>
</paramdef>
</funcprototype>
<funcprototype>
<funcdef>void <function>crypto_freereq</function></funcdef>
<paramdef>
<parameter>void</parameter>
</paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 id="driverside_api"><title>DRIVER-SIDE API</title> <para>The
crypto_get_driverid(,); crypto_register(,); crypto_kregister(,);
crypto_unregister(,); crypto_unblock(,); and 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 crypto_get_driverid(); function to acquire a driver
identifier, specifying the <emphasis remap="Fa">cc_flags</emphasis> as an
argument (normally 0, but software-only drivers should specify
<constant>CRYPTOCAP_F_SOFTWARE</constant>). For each algorithm the driver
supports, it must then call 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 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. 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. 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.</para> <para>The
calling convention for the three driver-supplied routines is:</para>
<itemizedlist remap="Bl -item -compact">
<listitem>
<para><type remap="Ft"> int </type> (*newsession)(void *, u_int32_t *,
struct cryptoini *);</para>
</listitem>
<listitem>
<para><type remap="Ft"> int </type> (*freesession)(void *,
u_int64_t);</para>
</listitem>
<listitem>
<para><type remap="Ft"> int </type> (*process)(void *, struct cryptop
*);</para>
</listitem>
<listitem>
<para><type remap="Ft"> int </type> (*kprocess)(void *, struct
cryptkop *);</para>
</listitem>
</itemizedlist> <para>On invocation, the first argument to all routines is
an opaque data value supplied when the algorithm is registered with
crypto_register(.); The second argument to newsession(); contains the driver
identifier obtained via crypto_get_driverid(.); On successful return, it
should contain a driver-specific session identifier. The third argument is
identical to that of crypto_newsession(.);</para> <para>The 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.).</para> <para>The 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
<varname>crp_etype</varname> field of the</para> <vartype>cryptop</vartype>
structure. When the request is completed, or an error is detected, the
process(); routine should invoke crypto_done(.); Session migration may be
performed, as mentioned previously. <para>In case of a temporary resource
exhaustion, the process(); routine may return
<errorcode>ERESTART</errorcode> in which case the crypto services will
requeue the request, mark the driver as “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
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.</para> <para>The 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
<varname>krp_status</varname> field of the</para>
<vartype>cryptkop</vartype> structure. When the request is completed, or an
error is detected, the kprocess(); routine should invoked
crypto_kdone(.);</refsect1>
<refsect1 id="return_values"><title>RETURN VALUES</title>
<para>crypto_register(); crypto_kregister(); crypto_unregister();
crypto_newsession(); crypto_freesession(,); and crypto_unblock(); return 0
on success, or an error code on failure. crypto_get_driverid(); returns a
non-negative value on error, and -1 on failure. crypto_getreq(); returns a
pointer to a</para> <vartype>cryptop</vartype> structure and
<constant>NULL</constant> on failure. crypto_dispatch(); returns
<errorcode>EINVAL</errorcode> if its argument or the callback function was
<constant>NULL</constant>, and 0 otherwise. The callback is provided with an
error code in case of failure, in the <varname>crp_etype</varname>
field.</refsect1>
<refsect1 id="files">
<title>FILES</title>
<variablelist remap="Bl -tag -width .Pa sys/opencrypto/crypto.c">
<varlistentry>
<term>
<filename>sys/opencrypto/crypto.c</filename>
</term>
<listitem>
<para>most of the framework code</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 id="see_also">
<title>SEE ALSO</title>
<para><citerefentry>
<refentrytitle>ipsec</refentrytitle>
<manvolnum>4</manvolnum>
</citerefentry>, <citerefentry>
<refentrytitle>malloc</refentrytitle>
<manvolnum>9</manvolnum>
</citerefentry>, <citerefentry>
<refentrytitle>sleep</refentrytitle>
<manvolnum>9</manvolnum>
</citerefentry></para>
</refsect1>
<refsect1 id="history">
<title>HISTORY</title>
<para>The cryptographic framework first appeared in <productname>OpenBSD
2.7</productname> and was written by <phrase role="author ">Angelos D.
Keromytis <angelos@openbsd.org></phrase>. It was ported to FreeBSD
by Sam Leffler. It was ported to Openswan by David McCullough.</para>
</refsect1>
<refsect1 id="bugs">
<title>BUGS</title>
<para>The framework currently assumes that all the algorithms in a
crypto_newsession(); operation must be available by the same driver. If
that is not the case, session initialization will fail.</para>
<para>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.</para>
<para>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.</para>
</refsect1>
</refentry>
