randomdev.c   [plain text]

/*
 * Copyright (c) 1999-2006 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/errno.h>
#include <sys/ioctl.h>
#include <sys/conf.h>
#include <sys/fcntl.h>
#include <string.h>
#include <miscfs/devfs/devfs.h>
#include <kern/lock.h>
#include <kern/clock.h>
#include <sys/time.h>
#include <sys/malloc.h>
#include <sys/uio_internal.h>

#include <dev/random/randomdev.h>
#include <dev/random/YarrowCoreLib/include/yarrow.h>
#include <libkern/crypto/sha1.h>

#include <mach/mach_time.h>
#include <machine/machine_routines.h>

#define RANDOM_MAJOR  -1 /* let the kernel pick the device number */

d_ioctl_t       random_ioctl;

/*
 * A struct describing which functions will get invoked for certain
 * actions.
 */
static struct cdevsw random_cdevsw =
{
	random_open,		/* open */
	random_close,		/* close */
	random_read,		/* read */
	random_write,		/* write */
	random_ioctl,		/* ioctl */
	(stop_fcn_t *)nulldev, /* stop */
	(reset_fcn_t *)nulldev, /* reset */
	NULL,				/* tty's */
	eno_select,			/* select */
	eno_mmap,			/* mmap */
	eno_strat,			/* strategy */
	eno_getc,			/* getc */
	eno_putc,			/* putc */
	0					/* type */
};

/* Used to detect whether we've already been initialized */
static int gRandomInstalled = 0;
static PrngRef gPrngRef;
static int gRandomError = 1;
static lck_grp_t *gYarrowGrp;
static lck_attr_t *gYarrowAttr;
static lck_grp_attr_t *gYarrowGrpAttr;
static lck_mtx_t *gYarrowMutex = 0;

void CheckReseed(void);

#define RESEED_TICKS 50 /* how long a reseed operation can take */


enum {kBSizeInBits = 160}; // MUST be a multiple of 32!!!
enum {kBSizeInBytes = kBSizeInBits / 8};
typedef u_int32_t BlockWord;
enum {kWordSizeInBits = 32};
enum {kBSize = 5};
typedef BlockWord Block[kBSize];

/* define prototypes to keep the compiler happy... */

void add_blocks(Block a, Block b, BlockWord carry);
void fips_initialize(void);
void random_block(Block b, int addOptional);
u_int32_t CalculateCRC(u_int8_t* buffer, size_t length);

/*
 * Get 120 bits from yarrow
 */

/*
 * add block b to block a
 */
void
add_blocks(Block a, Block b, BlockWord carry)
{
	int i = kBSize;
	while (--i >= 0)
	{
		u_int64_t c = (u_int64_t)carry +
					  (u_int64_t)a[i] +
					  (u_int64_t)b[i];
		a[i] = c & ((1LL << kWordSizeInBits) - 1);
		carry = c >> kWordSizeInBits;
	}
}



struct sha1_ctxt g_sha1_ctx;
char zeros[(512 - kBSizeInBits) / 8];
Block g_xkey;
Block g_random_data;
int g_bytes_used;
unsigned char g_SelfTestInitialized = 0;
u_int32_t gLastBlockChecksum;

static const u_int32_t g_crc_table[] =
{
	0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419, 0x706AF48F, 0xE963A535, 0x9E6495A3,
	0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988, 0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91,
	0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE, 0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7,
	0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9, 0xFA0F3D63, 0x8D080DF5,
	0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172, 0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B,
	0x35B5A8FA, 0x42B2986C, 0xDBBBC9D6, 0xACBCF940, 0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59,
	0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423, 0xCFBA9599, 0xB8BDA50F,
	0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924, 0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D,
	0x76DC4190, 0x01DB7106, 0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433,
	0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, 0x7F6A0DBB, 0x086D3D2D, 0x91646C97, 0xE6635C01,
	0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E, 0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457,
	0x65B0D9C6, 0x12B7E950, 0x8BBEB8EA, 0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65,
	0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2, 0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB,
	0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0, 0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9,
	0x5005713C, 0x270241AA, 0xBE0B1010, 0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F,
	0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17, 0x2EB40D81, 0xB7BD5C3B, 0xC0BA6CAD,
	0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A, 0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683,
	0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8, 0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1,
	0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB, 0x196C3671, 0x6E6B06E7,
	0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC, 0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5,
	0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B,
	0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55, 0x316E8EEF, 0x4669BE79,
	0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236, 0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F,
	0xC5BA3BBE, 0xB2BD0B28, 0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D,
	0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A, 0x9C0906A9, 0xEB0E363F, 0x72076785, 0x05005713,
	0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38, 0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21,
	0x86D3D2D4, 0xF1D4E242, 0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777,
	0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C, 0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45,
	0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2, 0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB,
	0xAED16A4A, 0xD9D65ADC, 0x40DF0B66, 0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9,
	0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605, 0xCDD70693, 0x54DE5729, 0x23D967BF,
	0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94, 0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D,
};

/*
 * Setup for fips compliance
 */

/*
 * calculate a crc-32 checksum
 */
u_int32_t CalculateCRC(u_int8_t* buffer, size_t length)
{
	u_int32_t crc = 0;
	
	size_t i;
	for (i = 0; i < length; ++i)
	{
		u_int32_t temp = (crc ^ ((u_int32_t) buffer[i])) & 0xFF;
		crc = (crc >> 8) ^ g_crc_table[temp];
	}
	
	return crc;
}

/*
 * get a random block of data per fips 186-2
 */
void
random_block(Block b, int addOptional)
{
	int repeatCount = 0;
	do
	{
		// do one iteration
		
		if (addOptional)
		{
			Block xSeed;
			prngOutput (gPrngRef, (BYTE*) &xSeed, sizeof (xSeed));
			
			// add the seed to the previous value of g_xkey
			add_blocks (g_xkey, xSeed, 0);
		}
		
		// compute "G"
		SHA1Update (&g_sha1_ctx, (const u_int8_t *) &g_xkey, sizeof (g_xkey));
		
		// add zeros to fill the internal SHA-1 buffer
		SHA1Update (&g_sha1_ctx, (const u_int8_t *)zeros, sizeof (zeros));
		
		// write the resulting block
		memmove(b, g_sha1_ctx.h.b8, sizeof (Block));
		
		// calculate the CRC-32 of the block
		u_int32_t new_crc = CalculateCRC(g_sha1_ctx.h.b8, sizeof (Block));
		
		// make sure we don't repeat
		int cmp = new_crc == gLastBlockChecksum;
		gLastBlockChecksum = new_crc;
		if (!g_SelfTestInitialized)
		{
			g_SelfTestInitialized = 1;
			return;
		}
		else if (!cmp)
		{
			return;
		}
		
		repeatCount += 1;
		
		// fix up the next value of g_xkey
		add_blocks (g_xkey, b, 1);
	} while (repeatCount < 2);
	
	/*
	 * If we got here, three sucessive checksums of the random number
	 * generator have been the same.  Since the odds of this happening are
	 * 1 in 18,446,744,073,709,551,616, (1 in 18 quintillion) one of the following has
	 * most likely happened:
	 *
	 * 1: There is a significant bug in this code.
	 * 2: There has been a massive system failure.
	 * 3: The universe has ceased to exist.
	 *
	 * There is no good way to recover from any of these cases. We
	 * therefore panic.
	 */
	 
	 panic("FIPS random self-test failed.");
}

/*
 *Initialize ONLY the Yarrow generator.
 */
void
PreliminarySetup(void)
{
    prng_error_status perr;

    /* create a Yarrow object */
    perr = prngInitialize(&gPrngRef);
    if (perr != 0) {
        printf ("Couldn't initialize Yarrow, /dev/random will not work.\n");
        return;
    }

	/* clear the error flag, reads and write should then work */
    gRandomError = 0;

   {
    struct timeval tt;
    char buffer [16];

    /* get a little non-deterministic data as an initial seed. */
    microtime(&tt);

    /*
	 * So how much of the system clock is entropic?
	 * It's hard to say, but assume that at least the
	 * least significant byte of a 64 bit structure
	 * is entropic.  It's probably more, how can you figure
	 * the exact time the user turned the computer on, for example.
    */
    perr = prngInput(gPrngRef, (BYTE*) &tt, sizeof (tt), SYSTEM_SOURCE, 8);
    if (perr != 0) {
        /* an error, complain */
        printf ("Couldn't seed Yarrow.\n");
        return;
    }
    
    /* turn the data around */
    perr = prngOutput(gPrngRef, (BYTE*) buffer, sizeof (buffer));
    
    /* and scramble it some more */
    perr = prngForceReseed(gPrngRef, RESEED_TICKS);
    }
    
    /* make a mutex to control access */
    gYarrowGrpAttr = lck_grp_attr_alloc_init();
    gYarrowGrp     = lck_grp_alloc_init("random", gYarrowGrpAttr);
    gYarrowAttr    = lck_attr_alloc_init();
    gYarrowMutex   = lck_mtx_alloc_init(gYarrowGrp, gYarrowAttr);
	
	fips_initialize ();
}

const Block kKnownAnswer = {0x92b404e5, 0x56588ced, 0x6c1acd4e, 0xbf053f68, 0x9f73a93};

void
fips_initialize(void)
{
	/* So that we can do the self test, set the seed to zero */
	memset(&g_xkey, 0, sizeof(g_xkey));
	
	/* initialize our SHA1 generator */
	SHA1Init (&g_sha1_ctx);
	
	/* other initializations */
	memset (zeros, 0, sizeof (zeros));
	g_bytes_used = 0;
	random_block(g_random_data, FALSE);
	
	// check here to see if we got the initial data we were expecting
	int i;
	for (i = 0; i < kBSize; ++i)
	{
		if (kKnownAnswer[i] != g_random_data[i])
		{
			panic("FIPS random self test failed");
		}
	}
	
	// now do the random block again to make sure that userland doesn't get predicatable data
	random_block(g_random_data, TRUE);
}

/*
 * Called to initialize our device,
 * and to register ourselves with devfs
 */
void
random_init(void)
{
	int ret;

	if (gRandomInstalled)
		return;

	/* install us in the file system */
	gRandomInstalled = 1;

#ifndef ARM_BOARD_CONFIG_S5L8900XFPGA_1136JFS
	/* setup yarrow and the mutex */
	PreliminarySetup();
#endif

	ret = cdevsw_add(RANDOM_MAJOR, &random_cdevsw);
	if (ret < 0) {
		printf("random_init: failed to allocate a major number!\n");
		gRandomInstalled = 0;
		return;
	}

	devfs_make_node(makedev (ret, 0), DEVFS_CHAR,
		UID_ROOT, GID_WHEEL, 0666, "random", 0);

	/*
	 * also make urandom 
	 * (which is exactly the same thing in our context)
	 */
	devfs_make_node(makedev (ret, 1), DEVFS_CHAR,
		UID_ROOT, GID_WHEEL, 0666, "urandom", 0);
}

int
random_ioctl(	__unused dev_t dev, u_long cmd, __unused caddr_t data, 
				__unused int flag, __unused struct proc *p  )
{
	switch (cmd) {
	case FIONBIO:
	case FIOASYNC:
		break;
	default:
		return ENODEV;
	}

	return (0);
}

/*
 * Open the device.  Make sure init happened, and make sure the caller is
 * authorized.
 */
 
int
random_open(__unused dev_t dev, int flags, __unused int devtype, __unused struct proc *p)
{
	if (gRandomError != 0) {
		/* forget it, yarrow didn't come up */
		return (ENOTSUP);
	}

	/*
	 * if we are being opened for write,
	 * make sure that we have privledges do so
	 */
	if (flags & FWRITE) {
		if (securelevel >= 2)
			return (EPERM);
#ifndef __APPLE__
		if ((securelevel >= 1) && proc_suser(p))
			return (EPERM);
#endif	/* !__APPLE__ */
	}

	return (0);
}


/*
 * close the device.
 */
 
int
random_close(__unused dev_t dev, __unused int flags, __unused int mode, __unused struct proc *p)
{
	return (0);
}


/*
 * Get entropic data from the Security Server, and use it to reseed the
 * prng.
 */
int
random_write (__unused dev_t dev, struct uio *uio, __unused int ioflag)
{
    int retCode = 0;
    char rdBuffer[256];

    if (gRandomError != 0) {
        return (ENOTSUP);
    }
    
    /* get control of the Yarrow instance, Yarrow is NOT thread safe */
    lck_mtx_lock(gYarrowMutex);
    
    /* Security server is sending us entropy */

    while (uio_resid(uio) > 0 && retCode == 0) {
        /* get the user's data */
        // LP64todo - fix this!  uio_resid may be 64-bit value
        int bytesToInput = min(uio_resid(uio), sizeof (rdBuffer));
        retCode = uiomove(rdBuffer, bytesToInput, uio);
        if (retCode != 0)
            goto /*ugh*/ error_exit;
        
        /* put it in Yarrow */
        if (prngInput(gPrngRef, (BYTE*) rdBuffer,
			bytesToInput, SYSTEM_SOURCE,
        	bytesToInput * 8) != 0) {
            retCode = EIO;
            goto error_exit;
        }
    }
    
    /* force a reseed */
    if (prngForceReseed(gPrngRef, RESEED_TICKS) != 0) {
        retCode = EIO;
        goto error_exit;
    }
    
    /* retCode should be 0 at this point */
    
error_exit: /* do this to make sure the mutex unlocks. */
    lck_mtx_unlock(gYarrowMutex);
    return (retCode);
}

/*
 * return data to the caller.  Results unpredictable.
 */ 
int
random_read(__unused dev_t dev, struct uio *uio, __unused int ioflag)
{
    int retCode = 0;
	
    if (gRandomError != 0)
        return (ENOTSUP);

   /* lock down the mutex */
    lck_mtx_lock(gYarrowMutex);

    CheckReseed();
	int bytes_remaining = uio_resid(uio);
    while (bytes_remaining > 0 && retCode == 0) {
        /* get the user's data */
		int bytes_to_read = 0;
		
		int bytes_available = kBSizeInBytes - g_bytes_used;
        if (bytes_available == 0)
		{
			random_block(g_random_data, TRUE);
			g_bytes_used = 0;
			bytes_available = kBSizeInBytes;
		}
		
		bytes_to_read = min (bytes_remaining, bytes_available);
		
        retCode = uiomove(((caddr_t)g_random_data)+ g_bytes_used, bytes_to_read, uio);
        g_bytes_used += bytes_to_read;

        if (retCode != 0)
            goto error_exit;
		
		bytes_remaining = uio_resid(uio);
    }
    
    retCode = 0;
    
error_exit:
    lck_mtx_unlock(gYarrowMutex);
    return retCode;
}

/* export good random numbers to the rest of the kernel */
void
read_random(void* buffer, u_int numbytes)
{
    if (gYarrowMutex == 0) { /* are we initialized? */
#ifndef ARM_BOARD_CONFIG_S5L8900XFPGA_1136JFS
        PreliminarySetup ();
#endif
    }
    
    lck_mtx_lock(gYarrowMutex);
    CheckReseed();

	int bytes_read = 0;

	int bytes_remaining = numbytes;
    while (bytes_remaining > 0) {
        int bytes_to_read = min(bytes_remaining, kBSizeInBytes - g_bytes_used);
        if (bytes_to_read == 0)
		{
			random_block(g_random_data, TRUE);
			g_bytes_used = 0;
			bytes_to_read = min(bytes_remaining, kBSizeInBytes);
		}
		
		memmove ((u_int8_t*) buffer + bytes_read, ((u_int8_t*)g_random_data)+ g_bytes_used, bytes_to_read);
		g_bytes_used += bytes_to_read;
		bytes_read += bytes_to_read;
		bytes_remaining -= bytes_to_read;
    }

    lck_mtx_unlock(gYarrowMutex);
}

/*
 * Return an unsigned long pseudo-random number.
 */
u_long
RandomULong(void)
{
	u_long buf;
	read_random(&buf, sizeof (buf));
	return (buf);
}

void
CheckReseed(void)
{
}