FreeBSD/Linux Kernel Cross Reference
sys/dev/random/other_algorithm.c

     /*-
      * Copyright (c) 2015-2018 Mark R V Murray
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
      *    notice, this list of conditions and the following disclaimer
     *    in this position and unchanged.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     *
     */
    
    /*-
     * This is a skeleton for folks who wish to build a loadable module
     * containing an alternative entropy-processing algorithm for random(4).
     *
     * The functions below should be completed with the appropriate code,
     * and the nearby fortuna.c may be consulted for examples of working code.
     *
     * The author is willing to provide reasonable help to those wishing to
     * write such a module for themselves. Please use the markm@ FreeBSD
     * email address, and ensure that you are developing this on a suitably
     * supported branch (This is currently 12-CURRENT, and may be no
     * older than 12-STABLE in the future).
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include <sys/limits.h>
    
    #ifdef _KERNEL
    #include <sys/param.h>
    #include <sys/kernel.h>
    #include <sys/lock.h>
    #include <sys/malloc.h>
    #include <sys/mutex.h>
    #include <sys/random.h>
    #include <sys/sysctl.h>
    #include <sys/systm.h>
    
    #include <machine/cpu.h>
    
    #include <crypto/rijndael/rijndael-api-fst.h>
    #include <crypto/sha2/sha256.h>
    
    #include <dev/random/hash.h>
    #include <dev/random/randomdev.h>
    #include <dev/random/random_harvestq.h>
    #include <dev/random/uint128.h>
    #include <dev/random/other_algorithm.h>
    #else /* !_KERNEL */
    #include <inttypes.h>
    #include <stdbool.h>
    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #include <threads.h>
    
    #include "unit_test.h"
    
    #include <crypto/rijndael/rijndael-api-fst.h>
    #include <crypto/sha2/sha256.h>
    
    #include <dev/random/hash.h>
    #include <dev/random/randomdev.h>
    #include <dev/random/uint128.h>
    #include <dev/random/other_algorithm.h>
    #endif /* _KERNEL */
    
    static void random_other_pre_read(void);
    static void random_other_read(uint8_t *, size_t);
    static bool random_other_seeded(void);
    static void random_other_process_event(struct harvest_event *);
    
    /*
     * RANDOM_OTHER_NPOOLS is used when reading hardware random
     * number sources to ensure that each pool gets one read sample
     * per loop iteration. Fortuna has 32 (0-31).
     */
    #define RANDOM_OTHER_NPOOLS 1
    
    #ifdef RANDOM_LOADABLE
    static
   #endif
   const struct random_algorithm random_alg_context = {
           .ra_ident = "other",
           .ra_pre_read = random_other_pre_read,
           .ra_read = random_other_read,
           .ra_seeded = random_other_seeded,
           .ra_event_processor = random_other_process_event,
           .ra_poolcount = RANDOM_OTHER_NPOOLS,
   };
   
   /* Use a mutex to protect your reseed variables? */
   static mtx_t other_mtx;
   
   /*
    * Do algorithm-specific initialisation here.
    */
   static void
   random_other_init_alg(void *unused __unused)
   {
   
   #ifdef RANDOM_LOADABLE
           p_random_alg_context = &random_alg_context;
   #endif
   
           RANDOM_RESEED_INIT_LOCK();
   }
   SYSINIT(random_alg, SI_SUB_RANDOM, SI_ORDER_SECOND, random_other_init_alg,
       NULL);
   
   /*
    * void random_other_pre_read(void)
    *
    * Do any pre-read preparation you need to. This will be called
    * before >=1 calls to random_other_read() corresponding to one
    * read(2).
    *
    * This routine will be called periodically while the generator is
    * still blocked and a read is being attempted, giving you an
    * opportunity to unblock.
    */
   static void
   random_other_pre_read(void)
   {
   
           RANDOM_RESEED_LOCK();
           /*
            * Do pre-read housekeeping work here!
            * You may use this as a chance to unblock the generator.
            */
           RANDOM_RESEED_UNLOCK();
   }
   
   /*
    * void random_other_read(uint8_t *buf, size_t count)
    *
    * Generate <count> bytes of output into <*buf>.
    * You may NOT use the fact that <count> will be a multiple of
    * RANDOM_BLOCKSIZE for optimization purposes.
    *
    * This function will always be called with your generator
    * unblocked and ready. If you are not ready to generate
    * output here, then feel free to KASSERT() or panic().
    */
   static void
   random_other_read(uint8_t *buf, size_t count)
   {
   
           RANDOM_RESEED_LOCK();
           /*
            * Do random-number generation work here!
            */
           RANDOM_RESEED_UNLOCK();
   }
   
   /*
    * bool random_other_seeded(void)
    *
    * Return true if your generator is ready to generate
    * output, and false otherwise.
    */
   static bool
   random_other_seeded(void)
   {
           bool seeded = false;
   
           /*
            * Find out if your generator is seeded here!
            */
           return (seeded);
   }
   
   /*
    * void random_other_process_event(struct harvest_event *event)
    *
    * Process one stochastic event <*event> into your entropy
    * processor.
    *
    * The structure of the event may change, so it is easier to
    * just grab the whole thing into your accumulation system.
    * You may pick-and-choose bits, but please don't complain
    * when/if these change.
    */
   static void
   random_other_process_event(struct harvest_event *event)
   {
   
           RANDOM_RESEED_LOCK();
           /*
            * Do entropy accumulation work here!
            * You may use this as a chance to unblock the generator.
            */
           RANDOM_RESEED_UNLOCK();
   }

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