diff options
| -rw-r--r-- | lib/random32.c | 49 |
1 files changed, 28 insertions, 21 deletions
diff --git a/lib/random32.c b/lib/random32.c index fa5da61ce7ad..c9b6bf3afe0c 100644 --- a/lib/random32.c +++ b/lib/random32.c @@ -40,6 +40,10 @@ #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); @@ -53,8 +57,7 @@ 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); @@ -147,21 +150,25 @@ 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); + u32 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); } /** @@ -194,14 +201,13 @@ 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); } @@ -210,6 +216,7 @@ static int __init prandom_init(void) 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) @@ -419,7 +426,7 @@ 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)) @@ -434,7 +441,7 @@ 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++) |