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-rw-r--r--lib/random32.c175
1 files changed, 96 insertions, 79 deletions
diff --git a/lib/random32.c b/lib/random32.c
index 1e5b2df44291..0bee183fa18f 100644
--- a/lib/random32.c
+++ b/lib/random32.c
@@ -1,37 +1,35 @@
/*
- This is a maximally equidistributed combined Tausworthe generator
- based on code from GNU Scientific Library 1.5 (30 Jun 2004)
-
- lfsr113 version:
-
- x_n = (s1_n ^ s2_n ^ s3_n ^ s4_n)
-
- s1_{n+1} = (((s1_n & 4294967294) << 18) ^ (((s1_n << 6) ^ s1_n) >> 13))
- s2_{n+1} = (((s2_n & 4294967288) << 2) ^ (((s2_n << 2) ^ s2_n) >> 27))
- s3_{n+1} = (((s3_n & 4294967280) << 7) ^ (((s3_n << 13) ^ s3_n) >> 21))
- s4_{n+1} = (((s4_n & 4294967168) << 13) ^ (((s4_n << 3) ^ s4_n) >> 12))
-
- The period of this generator is about 2^113 (see erratum paper).
-
- From: P. L'Ecuyer, "Maximally Equidistributed Combined Tausworthe
- Generators", Mathematics of Computation, 65, 213 (1996), 203--213:
- http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps
- ftp://ftp.iro.umontreal.ca/pub/simulation/lecuyer/papers/tausme.ps
-
- There is an erratum in the paper "Tables of Maximally
- Equidistributed Combined LFSR Generators", Mathematics of
- Computation, 68, 225 (1999), 261--269:
- http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps
-
- ... the k_j most significant bits of z_j must be non-
- zero, for each j. (Note: this restriction also applies to the
- computer code given in [4], but was mistakenly not mentioned in
- that paper.)
-
- This affects the seeding procedure by imposing the requirement
- s1 > 1, s2 > 7, s3 > 15, s4 > 127.
-
-*/
+ * This is a maximally equidistributed combined Tausworthe generator
+ * based on code from GNU Scientific Library 1.5 (30 Jun 2004)
+ *
+ * lfsr113 version:
+ *
+ * x_n = (s1_n ^ s2_n ^ s3_n ^ s4_n)
+ *
+ * s1_{n+1} = (((s1_n & 4294967294) << 18) ^ (((s1_n << 6) ^ s1_n) >> 13))
+ * s2_{n+1} = (((s2_n & 4294967288) << 2) ^ (((s2_n << 2) ^ s2_n) >> 27))
+ * s3_{n+1} = (((s3_n & 4294967280) << 7) ^ (((s3_n << 13) ^ s3_n) >> 21))
+ * s4_{n+1} = (((s4_n & 4294967168) << 13) ^ (((s4_n << 3) ^ s4_n) >> 12))
+ *
+ * The period of this generator is about 2^113 (see erratum paper).
+ *
+ * From: P. L'Ecuyer, "Maximally Equidistributed Combined Tausworthe
+ * Generators", Mathematics of Computation, 65, 213 (1996), 203--213:
+ * http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps
+ * ftp://ftp.iro.umontreal.ca/pub/simulation/lecuyer/papers/tausme.ps
+ *
+ * There is an erratum in the paper "Tables of Maximally Equidistributed
+ * Combined LFSR Generators", Mathematics of Computation, 68, 225 (1999),
+ * 261--269: http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps
+ *
+ * ... the k_j most significant bits of z_j must be non-zero,
+ * for each j. (Note: this restriction also applies to the
+ * computer code given in [4], but was mistakenly not mentioned
+ * in that paper.)
+ *
+ * This affects the seeding procedure by imposing the requirement
+ * s1 > 1, s2 > 7, s3 > 15, s4 > 127.
+ */
#include <linux/types.h>
#include <linux/percpu.h>
@@ -39,9 +37,14 @@
#include <linux/jiffies.h>
#include <linux/random.h>
#include <linux/sched.h>
+#include <asm/unaligned.h>
#ifdef CONFIG_RANDOM32_SELFTEST
static void __init prandom_state_selftest(void);
+#else
+static inline void prandom_state_selftest(void)
+{
+}
#endif
static DEFINE_PER_CPU(struct rnd_state, net_rand_state);
@@ -55,8 +58,7 @@ static DEFINE_PER_CPU(struct rnd_state, net_rand_state);
*/
u32 prandom_u32_state(struct rnd_state *state)
{
-#define TAUSWORTHE(s,a,b,c,d) ((s&c)<<d) ^ (((s <<a) ^ s)>>b)
-
+#define TAUSWORTHE(s, a, b, c, d) ((s & c) << d) ^ (((s << a) ^ s) >> b)
state->s1 = TAUSWORTHE(state->s1, 6U, 13U, 4294967294U, 18U);
state->s2 = TAUSWORTHE(state->s2, 2U, 27U, 4294967288U, 2U);
state->s3 = TAUSWORTHE(state->s3, 13U, 21U, 4294967280U, 7U);
@@ -75,15 +77,17 @@ EXPORT_SYMBOL(prandom_u32_state);
*/
u32 prandom_u32(void)
{
- unsigned long r;
struct rnd_state *state = &get_cpu_var(net_rand_state);
- r = prandom_u32_state(state);
+ u32 res;
+
+ res = prandom_u32_state(state);
put_cpu_var(state);
- return r;
+
+ return res;
}
EXPORT_SYMBOL(prandom_u32);
-/*
+/**
* prandom_bytes_state - get the requested number of pseudo-random bytes
*
* @state: pointer to state structure holding seeded state.
@@ -93,27 +97,23 @@ EXPORT_SYMBOL(prandom_u32);
* This is used for pseudo-randomness with no outside seeding.
* For more random results, use prandom_bytes().
*/
-void prandom_bytes_state(struct rnd_state *state, void *buf, int bytes)
+void prandom_bytes_state(struct rnd_state *state, void *buf, size_t bytes)
{
- unsigned char *p = buf;
- int i;
+ u8 *ptr = buf;
- for (i = 0; i < round_down(bytes, sizeof(u32)); i += sizeof(u32)) {
- u32 random = prandom_u32_state(state);
- int j;
-
- for (j = 0; j < sizeof(u32); j++) {
- p[i + j] = random;
- random >>= BITS_PER_BYTE;
- }
+ while (bytes >= sizeof(u32)) {
+ put_unaligned(prandom_u32_state(state), (u32 *) ptr);
+ ptr += sizeof(u32);
+ bytes -= sizeof(u32);
}
- if (i < bytes) {
- u32 random = prandom_u32_state(state);
- for (; i < bytes; i++) {
- p[i] = random;
- random >>= BITS_PER_BYTE;
- }
+ if (bytes > 0) {
+ u32 rem = prandom_u32_state(state);
+ do {
+ *ptr++ = (u8) rem;
+ bytes--;
+ rem >>= BITS_PER_BYTE;
+ } while (bytes > 0);
}
}
EXPORT_SYMBOL(prandom_bytes_state);
@@ -123,7 +123,7 @@ EXPORT_SYMBOL(prandom_bytes_state);
* @buf: where to copy the pseudo-random bytes to
* @bytes: the requested number of bytes
*/
-void prandom_bytes(void *buf, int bytes)
+void prandom_bytes(void *buf, size_t bytes)
{
struct rnd_state *state = &get_cpu_var(net_rand_state);
@@ -134,7 +134,7 @@ EXPORT_SYMBOL(prandom_bytes);
static void prandom_warmup(struct rnd_state *state)
{
- /* Calling RNG ten times to satify recurrence condition */
+ /* Calling RNG ten times to satisfy recurrence condition */
prandom_u32_state(state);
prandom_u32_state(state);
prandom_u32_state(state);
@@ -147,21 +147,25 @@ static void prandom_warmup(struct rnd_state *state)
prandom_u32_state(state);
}
-static void prandom_seed_very_weak(struct rnd_state *state, u32 seed)
+static u32 __extract_hwseed(void)
{
- /* Note: This sort of seeding is ONLY used in test cases and
- * during boot at the time from core_initcall until late_initcall
- * as we don't have a stronger entropy source available yet.
- * After late_initcall, we reseed entire state, we have to (!),
- * otherwise an attacker just needs to search 32 bit space to
- * probe for our internal 128 bit state if he knows a couple
- * of prandom32 outputs!
- */
-#define LCG(x) ((x) * 69069U) /* super-duper LCG */
- state->s1 = __seed(LCG(seed), 2U);
- state->s2 = __seed(LCG(state->s1), 8U);
- state->s3 = __seed(LCG(state->s2), 16U);
- state->s4 = __seed(LCG(state->s3), 128U);
+ unsigned int val = 0;
+
+ (void)(arch_get_random_seed_int(&val) ||
+ arch_get_random_int(&val));
+
+ return val;
+}
+
+static void prandom_seed_early(struct rnd_state *state, u32 seed,
+ bool mix_with_hwseed)
+{
+#define LCG(x) ((x) * 69069U) /* super-duper LCG */
+#define HWSEED() (mix_with_hwseed ? __extract_hwseed() : 0)
+ state->s1 = __seed(HWSEED() ^ LCG(seed), 2U);
+ state->s2 = __seed(HWSEED() ^ LCG(state->s1), 8U);
+ state->s3 = __seed(HWSEED() ^ LCG(state->s2), 16U);
+ state->s4 = __seed(HWSEED() ^ LCG(state->s3), 128U);
}
/**
@@ -194,21 +198,22 @@ static int __init prandom_init(void)
{
int i;
-#ifdef CONFIG_RANDOM32_SELFTEST
prandom_state_selftest();
-#endif
for_each_possible_cpu(i) {
struct rnd_state *state = &per_cpu(net_rand_state,i);
+ u32 weak_seed = (i + jiffies) ^ random_get_entropy();
- prandom_seed_very_weak(state, (i + jiffies) ^ random_get_entropy());
+ prandom_seed_early(state, weak_seed, true);
prandom_warmup(state);
}
+
return 0;
}
core_initcall(prandom_init);
static void __prandom_timer(unsigned long dontcare);
+
static DEFINE_TIMER(seed_timer, __prandom_timer, 0, 0);
static void __prandom_timer(unsigned long dontcare)
@@ -220,7 +225,7 @@ static void __prandom_timer(unsigned long dontcare)
prandom_seed(entropy);
/* reseed every ~60 seconds, in [40 .. 80) interval with slack */
- expires = 40 + (prandom_u32() % 40);
+ expires = 40 + prandom_u32_max(40);
seed_timer.expires = jiffies + msecs_to_jiffies(expires * MSEC_PER_SEC);
add_timer(&seed_timer);
@@ -244,10 +249,22 @@ static void __prandom_reseed(bool late)
static bool latch = false;
static DEFINE_SPINLOCK(lock);
+ /* Asking for random bytes might result in bytes getting
+ * moved into the nonblocking pool and thus marking it
+ * as initialized. In this case we would double back into
+ * this function and attempt to do a late reseed.
+ * Ignore the pointless attempt to reseed again if we're
+ * already waiting for bytes when the nonblocking pool
+ * got initialized.
+ */
+
/* only allow initial seeding (late == false) once */
- spin_lock_irqsave(&lock, flags);
+ if (!spin_trylock_irqsave(&lock, flags))
+ return;
+
if (latch && !late)
goto out;
+
latch = true;
for_each_possible_cpu(i) {
@@ -406,7 +423,7 @@ static void __init prandom_state_selftest(void)
for (i = 0; i < ARRAY_SIZE(test1); i++) {
struct rnd_state state;
- prandom_seed_very_weak(&state, test1[i].seed);
+ prandom_seed_early(&state, test1[i].seed, false);
prandom_warmup(&state);
if (test1[i].result != prandom_u32_state(&state))
@@ -421,7 +438,7 @@ static void __init prandom_state_selftest(void)
for (i = 0; i < ARRAY_SIZE(test2); i++) {
struct rnd_state state;
- prandom_seed_very_weak(&state, test2[i].seed);
+ prandom_seed_early(&state, test2[i].seed, false);
prandom_warmup(&state);
for (j = 0; j < test2[i].iteration - 1; j++)
generated by cgit v1.2.3 (git 2.25.1) at 2025-12-12 21:34:09 +0000