diff options
Diffstat (limited to 'drivers/char')
-rw-r--r-- | drivers/char/random.c | 67 |
1 files changed, 30 insertions, 37 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c index ba8d63f52c05..349beb318757 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -430,14 +430,20 @@ static int random_write_wakeup_bits = 28 * OUTPUT_POOL_WORDS; * polynomial which improves the resulting TGFSR polynomial to be * irreducible, which we have made here. */ -static const struct poolinfo { - int poolbitshift, poolwords, poolbytes, poolfracbits; -#define S(x) ilog2(x)+5, (x), (x)*4, (x) << (ENTROPY_SHIFT+5) - int tap1, tap2, tap3, tap4, tap5; -} poolinfo_table[] = { - /* was: x^128 + x^103 + x^76 + x^51 +x^25 + x + 1 */ +enum poolinfo { + POOL_WORDS = 128, + POOL_WORDMASK = POOL_WORDS - 1, + POOL_BYTES = POOL_WORDS * sizeof(u32), + POOL_BITS = POOL_BYTES * 8, + POOL_BITSHIFT = ilog2(POOL_WORDS) + 5, + POOL_FRACBITS = POOL_WORDS << (ENTROPY_SHIFT + 5), + /* x^128 + x^104 + x^76 + x^51 +x^25 + x + 1 */ - { S(128), 104, 76, 51, 25, 1 }, + POOL_TAP1 = 104, + POOL_TAP2 = 76, + POOL_TAP3 = 51, + POOL_TAP4 = 25, + POOL_TAP5 = 1 }; /* @@ -503,7 +509,6 @@ MODULE_PARM_DESC(ratelimit_disable, "Disable random ratelimit suppression"); struct entropy_store; struct entropy_store { /* read-only data: */ - const struct poolinfo *poolinfo; __u32 *pool; const char *name; @@ -525,7 +530,6 @@ static void crng_reseed(struct crng_state *crng, struct entropy_store *r); static __u32 input_pool_data[INPUT_POOL_WORDS] __latent_entropy; static struct entropy_store input_pool = { - .poolinfo = &poolinfo_table[0], .name = "input", .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock), .pool = input_pool_data @@ -548,33 +552,26 @@ static __u32 const twist_table[8] = { static void _mix_pool_bytes(struct entropy_store *r, const void *in, int nbytes) { - unsigned long i, tap1, tap2, tap3, tap4, tap5; + unsigned long i; int input_rotate; - int wordmask = r->poolinfo->poolwords - 1; const unsigned char *bytes = in; __u32 w; - tap1 = r->poolinfo->tap1; - tap2 = r->poolinfo->tap2; - tap3 = r->poolinfo->tap3; - tap4 = r->poolinfo->tap4; - tap5 = r->poolinfo->tap5; - input_rotate = r->input_rotate; i = r->add_ptr; /* mix one byte at a time to simplify size handling and churn faster */ while (nbytes--) { w = rol32(*bytes++, input_rotate); - i = (i - 1) & wordmask; + i = (i - 1) & POOL_WORDMASK; /* XOR in the various taps */ w ^= r->pool[i]; - w ^= r->pool[(i + tap1) & wordmask]; - w ^= r->pool[(i + tap2) & wordmask]; - w ^= r->pool[(i + tap3) & wordmask]; - w ^= r->pool[(i + tap4) & wordmask]; - w ^= r->pool[(i + tap5) & wordmask]; + w ^= r->pool[(i + POOL_TAP1) & POOL_WORDMASK]; + w ^= r->pool[(i + POOL_TAP2) & POOL_WORDMASK]; + w ^= r->pool[(i + POOL_TAP3) & POOL_WORDMASK]; + w ^= r->pool[(i + POOL_TAP4) & POOL_WORDMASK]; + w ^= r->pool[(i + POOL_TAP5) & POOL_WORDMASK]; /* Mix the result back in with a twist */ r->pool[i] = (w >> 3) ^ twist_table[w & 7]; @@ -672,7 +669,6 @@ static void process_random_ready_list(void) static void credit_entropy_bits(struct entropy_store *r, int nbits) { int entropy_count, orig; - const int pool_size = r->poolinfo->poolfracbits; int nfrac = nbits << ENTROPY_SHIFT; if (!nbits) @@ -706,25 +702,25 @@ retry: * turns no matter how large nbits is. */ int pnfrac = nfrac; - const int s = r->poolinfo->poolbitshift + ENTROPY_SHIFT + 2; + const int s = POOL_BITSHIFT + ENTROPY_SHIFT + 2; /* The +2 corresponds to the /4 in the denominator */ do { - unsigned int anfrac = min(pnfrac, pool_size/2); + unsigned int anfrac = min(pnfrac, POOL_FRACBITS/2); unsigned int add = - ((pool_size - entropy_count)*anfrac*3) >> s; + ((POOL_FRACBITS - entropy_count)*anfrac*3) >> s; entropy_count += add; pnfrac -= anfrac; - } while (unlikely(entropy_count < pool_size-2 && pnfrac)); + } while (unlikely(entropy_count < POOL_FRACBITS-2 && pnfrac)); } if (WARN_ON(entropy_count < 0)) { pr_warn("negative entropy/overflow: pool %s count %d\n", r->name, entropy_count); entropy_count = 0; - } else if (entropy_count > pool_size) - entropy_count = pool_size; + } else if (entropy_count > POOL_FRACBITS) + entropy_count = POOL_FRACBITS; if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig) goto retry; @@ -741,13 +737,11 @@ retry: static int credit_entropy_bits_safe(struct entropy_store *r, int nbits) { - const int nbits_max = r->poolinfo->poolwords * 32; - if (nbits < 0) return -EINVAL; /* Cap the value to avoid overflows */ - nbits = min(nbits, nbits_max); + nbits = min(nbits, POOL_BITS); credit_entropy_bits(r, nbits); return 0; @@ -1343,7 +1337,7 @@ static size_t account(struct entropy_store *r, size_t nbytes, int min, int entropy_count, orig, have_bytes; size_t ibytes, nfrac; - BUG_ON(r->entropy_count > r->poolinfo->poolfracbits); + BUG_ON(r->entropy_count > POOL_FRACBITS); /* Can we pull enough? */ retry: @@ -1409,8 +1403,7 @@ static void extract_buf(struct entropy_store *r, __u8 *out) /* Generate a hash across the pool */ spin_lock_irqsave(&r->lock, flags); - blake2s_update(&state, (const u8 *)r->pool, - r->poolinfo->poolwords * sizeof(*r->pool)); + blake2s_update(&state, (const u8 *)r->pool, POOL_BYTES); blake2s_final(&state, hash); /* final zeros out state */ /* @@ -1766,7 +1759,7 @@ static void __init init_std_data(struct entropy_store *r) unsigned long rv; mix_pool_bytes(r, &now, sizeof(now)); - for (i = r->poolinfo->poolbytes; i > 0; i -= sizeof(rv)) { + for (i = POOL_BYTES; i > 0; i -= sizeof(rv)) { if (!arch_get_random_seed_long(&rv) && !arch_get_random_long(&rv)) rv = random_get_entropy(); |