📄 random.c

📁 讲述linux的初始化过程
💻 C
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#define SHA_CODE_SIZE 0/* * SHA transform algorithm, taken from code written by Peter Gutmann, * and placed in the public domain. *//* The SHA f()-functions.  */#define f1(x,y,z)   ( z ^ (x & (y^z)) )		/* Rounds  0-19: x ? y : z */#define f2(x,y,z)   (x ^ y ^ z)			/* Rounds 20-39: XOR */#define f3(x,y,z)   ( (x & y) + (z & (x ^ y)) )	/* Rounds 40-59: majority */#define f4(x,y,z)   (x ^ y ^ z)			/* Rounds 60-79: XOR *//* The SHA Mysterious Constants */#define K1  0x5A827999L			/* Rounds  0-19: sqrt(2) * 2^30 */#define K2  0x6ED9EBA1L			/* Rounds 20-39: sqrt(3) * 2^30 */#define K3  0x8F1BBCDCL			/* Rounds 40-59: sqrt(5) * 2^30 */#define K4  0xCA62C1D6L			/* Rounds 60-79: sqrt(10) * 2^30 */#define ROTL(n,X)  ( ( ( X ) << n ) | ( ( X ) >> ( 32 - n ) ) )#define subRound(a, b, c, d, e, f, k, data) \    ( e += ROTL( 5, a ) + f( b, c, d ) + k + data, b = ROTL( 30, b ) )static void SHATransform(__u32 digest[85], __u32 const data[16]){    __u32 A, B, C, D, E;     /* Local vars */    __u32 TEMP;    int	i;#define W (digest + HASH_BUFFER_SIZE)	/* Expanded data array */    /*     * Do the preliminary expansion of 16 to 80 words.  Doing it     * out-of-line line this is faster than doing it in-line on     * register-starved machines like the x86, and not really any     * slower on real processors.     */    memcpy(W, data, 16*sizeof(__u32));    for (i = 0; i < 64; i++) {	    TEMP = W[i] ^ W[i+2] ^ W[i+8] ^ W[i+13];	    W[i+16] = ROTL(1, TEMP);    }    /* Set up first buffer and local data buffer */    A = digest[ 0 ];    B = digest[ 1 ];    C = digest[ 2 ];    D = digest[ 3 ];    E = digest[ 4 ];    /* Heavy mangling, in 4 sub-rounds of 20 iterations each. */#if SHA_CODE_SIZE == 0    /*     * Approximately 50% of the speed of the largest version, but     * takes up 1/16 the space.  Saves about 6k on an i386 kernel.     */    for (i = 0; i < 80; i++) {	if (i < 40) {	    if (i < 20)		TEMP = f1(B, C, D) + K1;	    else		TEMP = f2(B, C, D) + K2;	} else {	    if (i < 60)		TEMP = f3(B, C, D) + K3;	    else		TEMP = f4(B, C, D) + K4;	}	TEMP += ROTL(5, A) + E + W[i];	E = D; D = C; C = ROTL(30, B); B = A; A = TEMP;    }#elif SHA_CODE_SIZE == 1    for (i = 0; i < 20; i++) {	TEMP = f1(B, C, D) + K1 + ROTL(5, A) + E + W[i];	E = D; D = C; C = ROTL(30, B); B = A; A = TEMP;    }    for (; i < 40; i++) {	TEMP = f2(B, C, D) + K2 + ROTL(5, A) + E + W[i];	E = D; D = C; C = ROTL(30, B); B = A; A = TEMP;    }    for (; i < 60; i++) {	TEMP = f3(B, C, D) + K3 + ROTL(5, A) + E + W[i];	E = D; D = C; C = ROTL(30, B); B = A; A = TEMP;    }    for (; i < 80; i++) {	TEMP = f4(B, C, D) + K4 + ROTL(5, A) + E + W[i];	E = D; D = C; C = ROTL(30, B); B = A; A = TEMP;    }#elif SHA_CODE_SIZE == 2    for (i = 0; i < 20; i += 5) {	subRound( A, B, C, D, E, f1, K1, W[ i   ] );	subRound( E, A, B, C, D, f1, K1, W[ i+1 ] );	subRound( D, E, A, B, C, f1, K1, W[ i+2 ] );	subRound( C, D, E, A, B, f1, K1, W[ i+3 ] );	subRound( B, C, D, E, A, f1, K1, W[ i+4 ] );    }    for (; i < 40; i += 5) {	subRound( A, B, C, D, E, f2, K2, W[ i   ] );	subRound( E, A, B, C, D, f2, K2, W[ i+1 ] );	subRound( D, E, A, B, C, f2, K2, W[ i+2 ] );	subRound( C, D, E, A, B, f2, K2, W[ i+3 ] );	subRound( B, C, D, E, A, f2, K2, W[ i+4 ] );    }    for (; i < 60; i += 5) {	subRound( A, B, C, D, E, f3, K3, W[ i   ] );	subRound( E, A, B, C, D, f3, K3, W[ i+1 ] );	subRound( D, E, A, B, C, f3, K3, W[ i+2 ] );	subRound( C, D, E, A, B, f3, K3, W[ i+3 ] );	subRound( B, C, D, E, A, f3, K3, W[ i+4 ] );    }    for (; i < 80; i += 5) {	subRound( A, B, C, D, E, f4, K4, W[ i   ] );	subRound( E, A, B, C, D, f4, K4, W[ i+1 ] );	subRound( D, E, A, B, C, f4, K4, W[ i+2 ] );	subRound( C, D, E, A, B, f4, K4, W[ i+3 ] );	subRound( B, C, D, E, A, f4, K4, W[ i+4 ] );    }#elif SHA_CODE_SIZE == 3 /* Really large version */    subRound( A, B, C, D, E, f1, K1, W[  0 ] );    subRound( E, A, B, C, D, f1, K1, W[  1 ] );    subRound( D, E, A, B, C, f1, K1, W[  2 ] );    subRound( C, D, E, A, B, f1, K1, W[  3 ] );    subRound( B, C, D, E, A, f1, K1, W[  4 ] );    subRound( A, B, C, D, E, f1, K1, W[  5 ] );    subRound( E, A, B, C, D, f1, K1, W[  6 ] );    subRound( D, E, A, B, C, f1, K1, W[  7 ] );    subRound( C, D, E, A, B, f1, K1, W[  8 ] );    subRound( B, C, D, E, A, f1, K1, W[  9 ] );    subRound( A, B, C, D, E, f1, K1, W[ 10 ] );    subRound( E, A, B, C, D, f1, K1, W[ 11 ] );    subRound( D, E, A, B, C, f1, K1, W[ 12 ] );    subRound( C, D, E, A, B, f1, K1, W[ 13 ] );    subRound( B, C, D, E, A, f1, K1, W[ 14 ] );    subRound( A, B, C, D, E, f1, K1, W[ 15 ] );    subRound( E, A, B, C, D, f1, K1, W[ 16 ] );    subRound( D, E, A, B, C, f1, K1, W[ 17 ] );    subRound( C, D, E, A, B, f1, K1, W[ 18 ] );    subRound( B, C, D, E, A, f1, K1, W[ 19 ] );    subRound( A, B, C, D, E, f2, K2, W[ 20 ] );    subRound( E, A, B, C, D, f2, K2, W[ 21 ] );    subRound( D, E, A, B, C, f2, K2, W[ 22 ] );    subRound( C, D, E, A, B, f2, K2, W[ 23 ] );    subRound( B, C, D, E, A, f2, K2, W[ 24 ] );    subRound( A, B, C, D, E, f2, K2, W[ 25 ] );    subRound( E, A, B, C, D, f2, K2, W[ 26 ] );    subRound( D, E, A, B, C, f2, K2, W[ 27 ] );    subRound( C, D, E, A, B, f2, K2, W[ 28 ] );    subRound( B, C, D, E, A, f2, K2, W[ 29 ] );    subRound( A, B, C, D, E, f2, K2, W[ 30 ] );    subRound( E, A, B, C, D, f2, K2, W[ 31 ] );    subRound( D, E, A, B, C, f2, K2, W[ 32 ] );    subRound( C, D, E, A, B, f2, K2, W[ 33 ] );    subRound( B, C, D, E, A, f2, K2, W[ 34 ] );    subRound( A, B, C, D, E, f2, K2, W[ 35 ] );    subRound( E, A, B, C, D, f2, K2, W[ 36 ] );    subRound( D, E, A, B, C, f2, K2, W[ 37 ] );    subRound( C, D, E, A, B, f2, K2, W[ 38 ] );    subRound( B, C, D, E, A, f2, K2, W[ 39 ] );        subRound( A, B, C, D, E, f3, K3, W[ 40 ] );    subRound( E, A, B, C, D, f3, K3, W[ 41 ] );    subRound( D, E, A, B, C, f3, K3, W[ 42 ] );    subRound( C, D, E, A, B, f3, K3, W[ 43 ] );    subRound( B, C, D, E, A, f3, K3, W[ 44 ] );    subRound( A, B, C, D, E, f3, K3, W[ 45 ] );    subRound( E, A, B, C, D, f3, K3, W[ 46 ] );    subRound( D, E, A, B, C, f3, K3, W[ 47 ] );    subRound( C, D, E, A, B, f3, K3, W[ 48 ] );    subRound( B, C, D, E, A, f3, K3, W[ 49 ] );    subRound( A, B, C, D, E, f3, K3, W[ 50 ] );    subRound( E, A, B, C, D, f3, K3, W[ 51 ] );    subRound( D, E, A, B, C, f3, K3, W[ 52 ] );    subRound( C, D, E, A, B, f3, K3, W[ 53 ] );    subRound( B, C, D, E, A, f3, K3, W[ 54 ] );    subRound( A, B, C, D, E, f3, K3, W[ 55 ] );    subRound( E, A, B, C, D, f3, K3, W[ 56 ] );    subRound( D, E, A, B, C, f3, K3, W[ 57 ] );    subRound( C, D, E, A, B, f3, K3, W[ 58 ] );    subRound( B, C, D, E, A, f3, K3, W[ 59 ] );    subRound( A, B, C, D, E, f4, K4, W[ 60 ] );    subRound( E, A, B, C, D, f4, K4, W[ 61 ] );    subRound( D, E, A, B, C, f4, K4, W[ 62 ] );    subRound( C, D, E, A, B, f4, K4, W[ 63 ] );    subRound( B, C, D, E, A, f4, K4, W[ 64 ] );    subRound( A, B, C, D, E, f4, K4, W[ 65 ] );    subRound( E, A, B, C, D, f4, K4, W[ 66 ] );    subRound( D, E, A, B, C, f4, K4, W[ 67 ] );    subRound( C, D, E, A, B, f4, K4, W[ 68 ] );    subRound( B, C, D, E, A, f4, K4, W[ 69 ] );    subRound( A, B, C, D, E, f4, K4, W[ 70 ] );    subRound( E, A, B, C, D, f4, K4, W[ 71 ] );    subRound( D, E, A, B, C, f4, K4, W[ 72 ] );    subRound( C, D, E, A, B, f4, K4, W[ 73 ] );    subRound( B, C, D, E, A, f4, K4, W[ 74 ] );    subRound( A, B, C, D, E, f4, K4, W[ 75 ] );    subRound( E, A, B, C, D, f4, K4, W[ 76 ] );    subRound( D, E, A, B, C, f4, K4, W[ 77 ] );    subRound( C, D, E, A, B, f4, K4, W[ 78 ] );    subRound( B, C, D, E, A, f4, K4, W[ 79 ] );#else#error Illegal SHA_CODE_SIZE#endif    /* Build message digest */    digest[ 0 ] += A;    digest[ 1 ] += B;    digest[ 2 ] += C;    digest[ 3 ] += D;    digest[ 4 ] += E;	/* W is wiped by the caller */#undef W}#undef ROTL#undef f1#undef f2#undef f3#undef f4#undef K1	#undef K2#undef K3	#undef K4	#undef subRound	#else /* !USE_SHA - Use MD5 */#define HASH_BUFFER_SIZE 4#define HASH_EXTRA_SIZE 0#define HASH_TRANSFORM MD5Transform	/* * MD5 transform algorithm, taken from code written by Colin Plumb, * and put into the public domain *//* The four core functions - F1 is optimized somewhat *//* #define F1(x, y, z) (x & y | ~x & z) */#define F1(x, y, z) (z ^ (x & (y ^ z)))#define F2(x, y, z) F1(z, x, y)#define F3(x, y, z) (x ^ y ^ z)#define F4(x, y, z) (y ^ (x | ~z))/* This is the central step in the MD5 algorithm. */#define MD5STEP(f, w, x, y, z, data, s) \	( w += f(x, y, z) + data,  w = w<<s | w>>(32-s),  w += x )/* * The core of the MD5 algorithm, this alters an existing MD5 hash to * reflect the addition of 16 longwords of new data.  MD5Update blocks * the data and converts bytes into longwords for this routine. */static void MD5Transform(__u32 buf[HASH_BUFFER_SIZE], __u32 const in[16]){	__u32 a, b, c, d;	a = buf[0];	b = buf[1];	c = buf[2];	d = buf[3];	MD5STEP(F1, a, b, c, d, in[ 0]+0xd76aa478,  7);	MD5STEP(F1, d, a, b, c, in[ 1]+0xe8c7b756, 12);	MD5STEP(F1, c, d, a, b, in[ 2]+0x242070db, 17);	MD5STEP(F1, b, c, d, a, in[ 3]+0xc1bdceee, 22);	MD5STEP(F1, a, b, c, d, in[ 4]+0xf57c0faf,  7);	MD5STEP(F1, d, a, b, c, in[ 5]+0x4787c62a, 12);	MD5STEP(F1, c, d, a, b, in[ 6]+0xa8304613, 17);	MD5STEP(F1, b, c, d, a, in[ 7]+0xfd469501, 22);	MD5STEP(F1, a, b, c, d, in[ 8]+0x698098d8,  7);	MD5STEP(F1, d, a, b, c, in[ 9]+0x8b44f7af, 12);	MD5STEP(F1, c, d, a, b, in[10]+0xffff5bb1, 17);	MD5STEP(F1, b, c, d, a, in[11]+0x895cd7be, 22);	MD5STEP(F1, a, b, c, d, in[12]+0x6b901122,  7);	MD5STEP(F1, d, a, b, c, in[13]+0xfd987193, 12);	MD5STEP(F1, c, d, a, b, in[14]+0xa679438e, 17);	MD5STEP(F1, b, c, d, a, in[15]+0x49b40821, 22);	MD5STEP(F2, a, b, c, d, in[ 1]+0xf61e2562,  5);	MD5STEP(F2, d, a, b, c, in[ 6]+0xc040b340,  9);	MD5STEP(F2, c, d, a, b, in[11]+0x265e5a51, 14);	MD5STEP(F2, b, c, d, a, in[ 0]+0xe9b6c7aa, 20);	MD5STEP(F2, a, b, c, d, in[ 5]+0xd62f105d,  5);	MD5STEP(F2, d, a, b, c, in[10]+0x02441453,  9);	MD5STEP(F2, c, d, a, b, in[15]+0xd8a1e681, 14);	MD5STEP(F2, b, c, d, a, in[ 4]+0xe7d3fbc8, 20);	MD5STEP(F2, a, b, c, d, in[ 9]+0x21e1cde6,  5);	MD5STEP(F2, d, a, b, c, in[14]+0xc33707d6,  9);	MD5STEP(F2, c, d, a, b, in[ 3]+0xf4d50d87, 14);	MD5STEP(F2, b, c, d, a, in[ 8]+0x455a14ed, 20);	MD5STEP(F2, a, b, c, d, in[13]+0xa9e3e905,  5);	MD5STEP(F2, d, a, b, c, in[ 2]+0xfcefa3f8,  9);	MD5STEP(F2, c, d, a, b, in[ 7]+0x676f02d9, 14);	MD5STEP(F2, b, c, d, a, in[12]+0x8d2a4c8a, 20);	MD5STEP(F3, a, b, c, d, in[ 5]+0xfffa3942,  4);	MD5STEP(F3, d, a, b, c, in[ 8]+0x8771f681, 11);	MD5STEP(F3, c, d, a, b, in[11]+0x6d9d6122, 16);	MD5STEP(F3, b, c, d, a, in[14]+0xfde5380c, 23);	MD5STEP(F3, a, b, c, d, in[ 1]+0xa4beea44,  4);	MD5STEP(F3, d, a, b, c, in[ 4]+0x4bdecfa9, 11);	MD5STEP(F3, c, d, a, b, in[ 7]+0xf6bb4b60, 16);	MD5STEP(F3, b, c, d, a, in[10]+0xbebfbc70, 23);	MD5STEP(F3, a, b, c, d, in[13]+0x289b7ec6,  4);	MD5STEP(F3, d, a, b, c, in[ 0]+0xeaa127fa, 11);	MD5STEP(F3, c, d, a, b, in[ 3]+0xd4ef3085, 16);	MD5STEP(F3, b, c, d, a, in[ 6]+0x04881d05, 23);	MD5STEP(F3, a, b, c, d, in[ 9]+0xd9d4d039,  4);	MD5STEP(F3, d, a, b, c, in[12]+0xe6db99e5, 11);	MD5STEP(F3, c, d, a, b, in[15]+0x1fa27cf8, 16);	MD5STEP(F3, b, c, d, a, in[ 2]+0xc4ac5665, 23);	MD5STEP(F4, a, b, c, d, in[ 0]+0xf4292244,  6);	MD5STEP(F4, d, a, b, c, in[ 7]+0x432aff97, 10);	MD5STEP(F4, c, d, a, b, in[14]+0xab9423a7, 15);	MD5STEP(F4, b, c, d, a, in[ 5]+0xfc93a039, 21);	MD5STEP(F4, a, b, c, d, in[12]+0x655b59c3,  6);	MD5STEP(F4, d, a, b, c, in[ 3]+0x8f0ccc92, 10);	MD5STEP(F4, c, d, a, b, in[10]+0xffeff47d, 15);	MD5STEP(F4, b, c, d, a, in[ 1]+0x85845dd1, 21);	MD5STEP(F4, a, b, c, d, in[ 8]+0x6fa87e4f,  6);	MD5STEP(F4, d, a, b, c, in[15]+0xfe2ce6e0, 10);	MD5STEP(F4, c, d, a, b, in[ 6]+0xa3014314, 15);	MD5STEP(F4, b, c, d, a, in[13]+0x4e0811a1, 21);	MD5STEP(F4, a, b, c, d, in[ 4]+0xf7537e82,  6);	MD5STEP(F4, d, a, b, c, in[11]+0xbd3af235, 10);	MD5STEP(F4, c, d, a, b, in[ 2]+0x2ad7d2bb, 15);	MD5STEP(F4, b, c, d, a, in[ 9]+0xeb86d391, 21);	buf[0] += a;	buf[1] += b;	buf[2] += c;	buf[3] += d;}#undef F1#undef F2#undef F3#undef F4#undef MD5STEP#endif /* !USE_SHA *//********************************************************************* * * Entropy extraction routines * *********************************************************************/#define EXTRACT_ENTROPY_USER		1#define EXTRACT_ENTROPY_SECONDARY	2#define TMP_BUF_SIZE			(HASH_BUFFER_SIZE + HASH_EXTRA_SIZE)#define SEC_XFER_SIZE			(TMP_BUF_SIZE*4)static ssize_t extract_entropy(struct entropy_store *r, void * buf,			       size_t nbytes, int flags);/* * This utility inline function is responsible for transfering entropy * from the primary pool to the secondary extraction pool.  We pull  * randomness under two conditions; one is if there isn't enough entropy  * in the secondary pool.  The other is after we have extract 1024 bytes, * at which point we do a "catastrophic reseeding". */static inline void xfer_secondary_pool(struct entropy_store *r,				       size_t nbytes){	__u32	tmp[TMP_BUF_SIZE];	if (r->entropy_count < nbytes*8) {		extract_entropy(random_state, tmp, sizeof(tmp), 0);		add_entropy_words(r, tmp, TMP_BUF_SIZE);		credit_entropy_store(r, TMP_BUF_SIZE*8);	}	if (r->extract_count > 1024) {		extract_entropy(random_state, tmp, sizeof(tmp), 0);		add_entropy_words(r, tmp, TMP_BUF_SIZE);		r->extract_count = 0;	}}/* * This function extracts randomness from the "entropy pool", and * returns it in a buffer.  This function computes how many remaining * bits of entropy are left in the pool, but it does not restrict the * number of bytes that are actually obtained.  If the EXTRACT_ENTROPY_USER * flag is given, then the buf pointer is assumed to be in user space. * If the EXTRACT_ENTROPY_SECONDARY flag is given, then this function will  * * Note: extract_entropy() assumes that POOLWORDS is a multiple of 16 words. */static ssize_t extract_entropy(struct entropy_store *r, void * buf,			       size_t nbytes, int flags){	ssize_t ret, i;	__u32 tmp[TMP_BUF_SIZE];	__u32 x;	add_timer_randomness(&extract_timer_state, nbytes);		/* Redundant, but just in case... */	if (r->entropy_count > r->poolinfo.poolwords) 		r->entropy_count = r->poolinfo.poolwords;	if (flags & EXTRACT_ENTROPY_SECONDARY)		xfer_secondary_pool(r, nbytes);	if (r->entropy_count / 8 >= nbytes)		r->entropy_count -= nbytes*8;	else		r->entropy_count = 0;	if (r->entropy_count < random_write_wakeup_thresh)
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