diff --git a/drivers/char/random.c b/drivers/char/random.c
index d20ba1b104ca3aceadd19fb6fbcb9ba035799a62..2a41b21623ae42b6efdf530287c5f7e20660e3a1 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1277,7 +1277,6 @@ void add_interrupt_randomness(int irq, int irq_flags)
fast_mix(fast_pool);
add_interrupt_bench(cycles);
- this_cpu_add(net_rand_state.s1, fast_pool->pool[cycles & 3]);
if (unlikely(crng_init == 0)) {
if ((fast_pool->count >= 64) &&
diff --git a/include/linux/prandom.h b/include/linux/prandom.h
index aa16e6468f91e79e1f31e2f49c0ca96950600188..bbf4b4ad61dfda9dc66da325d9a29d3b9e6cbf09 100644
--- a/include/linux/prandom.h
+++ b/include/linux/prandom.h
@@ -16,12 +16,62 @@ void prandom_bytes(void *buf, size_t nbytes);
void prandom_seed(u32 seed);
void prandom_reseed_late(void);
+DECLARE_PER_CPU(unsigned long, net_rand_noise);
+
+#define PRANDOM_ADD_NOISE(a, b, c, d) \
+ prandom_u32_add_noise((unsigned long)(a), (unsigned long)(b), \
+ (unsigned long)(c), (unsigned long)(d))
+
+#if BITS_PER_LONG == 64
+/*
+ * The core SipHash round function. Each line can be executed in
+ * parallel given enough CPU resources.
+ */
+#define PRND_SIPROUND(v0, v1, v2, v3) ( \
+ v0 += v1, v1 = rol64(v1, 13), v2 += v3, v3 = rol64(v3, 16), \
+ v1 ^= v0, v0 = rol64(v0, 32), v3 ^= v2, \
+ v0 += v3, v3 = rol64(v3, 21), v2 += v1, v1 = rol64(v1, 17), \
+ v3 ^= v0, v1 ^= v2, v2 = rol64(v2, 32) \
+)
+
+#define PRND_K0 (0x736f6d6570736575 ^ 0x6c7967656e657261)
+#define PRND_K1 (0x646f72616e646f6d ^ 0x7465646279746573)
+
+#elif BITS_PER_LONG == 32
+/*
+ * On 32-bit machines, we use HSipHash, a reduced-width version of SipHash.
+ * This is weaker, but 32-bit machines are not used for high-traffic
+ * applications, so there is less output for an attacker to analyze.
+ */
+#define PRND_SIPROUND(v0, v1, v2, v3) ( \
+ v0 += v1, v1 = rol32(v1, 5), v2 += v3, v3 = rol32(v3, 8), \
+ v1 ^= v0, v0 = rol32(v0, 16), v3 ^= v2, \
+ v0 += v3, v3 = rol32(v3, 7), v2 += v1, v1 = rol32(v1, 13), \
+ v3 ^= v0, v1 ^= v2, v2 = rol32(v2, 16) \
+)
+#define PRND_K0 0x6c796765
+#define PRND_K1 0x74656462
+
+#else
+#error Unsupported BITS_PER_LONG
+#endif
+
+static inline void prandom_u32_add_noise(unsigned long a, unsigned long b,
+ unsigned long c, unsigned long d)
+{
+ /*
+ * This is not used cryptographically; it's just
+ * a convenient 4-word hash function. (3 xor, 2 add, 2 rol)
+ */
+ a ^= raw_cpu_read(net_rand_noise);
+ PRND_SIPROUND(a, b, c, d);
+ raw_cpu_write(net_rand_noise, d);
+}
+
struct rnd_state {
__u32 s1, s2, s3, s4;
};
-DECLARE_PER_CPU(struct rnd_state, net_rand_state);
-
u32 prandom_u32_state(struct rnd_state *state);
void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes);
void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state);
@@ -67,6 +117,7 @@ static inline void prandom_seed_state(struct rnd_state *state, u64 seed)
state->s2 = __seed(i, 8U);
state->s3 = __seed(i, 16U);
state->s4 = __seed(i, 128U);
+ PRANDOM_ADD_NOISE(state, i, 0, 0);
}
/* Pseudo random number generator from numerical recipes. */
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index dda05f4b7a1f8ddcb5ffa1393b0922720a41f29e..de37e33a868dc0efa2c947804ebd7f4d01e07eba 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1706,6 +1706,8 @@ void update_process_times(int user_tick)
{
struct task_struct *p = current;
+ PRANDOM_ADD_NOISE(jiffies, user_tick, p, 0);
+
/* Note: this timer irq context must be accounted for as well. */
account_process_tick(p, user_tick);
run_local_timers();
@@ -1717,13 +1719,6 @@ void update_process_times(int user_tick)
scheduler_tick();
if (IS_ENABLED(CONFIG_POSIX_TIMERS))
run_posix_cpu_timers();
-
- /* The current CPU might make use of net randoms without receiving IRQs
- * to renew them often enough. Let's update the net_rand_state from a
- * non-constant value that's not affine to the number of calls to make
- * sure it's updated when there's some activity (we don't care in idle).
- */
- this_cpu_add(net_rand_state.s1, rol32(jiffies, 24) + user_tick);
}
/**
diff --git a/lib/random32.c b/lib/random32.c
index dfb9981ab7989640b807e6f9809b27465b6d521c..4d0e05e471d72979dbce4ae7ea562f740914e6eb 100644
--- a/lib/random32.c
+++ b/lib/random32.c
@@ -38,19 +38,10 @@
#include <linux/jiffies.h>
#include <linux/random.h>
#include <linux/sched.h>
+#include <linux/bitops.h>
#include <asm/unaligned.h>
#include <trace/events/random.h>
-#ifdef CONFIG_RANDOM32_SELFTEST
-static void __init prandom_state_selftest(void);
-#else
-static inline void prandom_state_selftest(void)
-{
-}
-#endif
-
-DEFINE_PER_CPU(struct rnd_state, net_rand_state) __latent_entropy;
-
/**
* prandom_u32_state - seeded pseudo-random number generator.
* @state: pointer to state structure holding seeded state.
@@ -70,26 +61,6 @@ u32 prandom_u32_state(struct rnd_state *state)
}
EXPORT_SYMBOL(prandom_u32_state);
-/**
- * prandom_u32 - pseudo random number generator
- *
- * A 32 bit pseudo-random number is generated using a fast
- * algorithm suitable for simulation. This algorithm is NOT
- * considered safe for cryptographic use.
- */
-u32 prandom_u32(void)
-{
- struct rnd_state *state = &get_cpu_var(net_rand_state);
- u32 res;
-
- res = prandom_u32_state(state);
- trace_prandom_u32(res);
- put_cpu_var(net_rand_state);
-
- return res;
-}
-EXPORT_SYMBOL(prandom_u32);
-
/**
* prandom_bytes_state - get the requested number of pseudo-random bytes
*
@@ -121,20 +92,6 @@ void prandom_bytes_state(struct rnd_state *state, void *buf, size_t bytes)
}
EXPORT_SYMBOL(prandom_bytes_state);
-/**
- * prandom_bytes - get the requested number of pseudo-random bytes
- * @buf: where to copy the pseudo-random bytes to
- * @bytes: the requested number of bytes
- */
-void prandom_bytes(void *buf, size_t bytes)
-{
- struct rnd_state *state = &get_cpu_var(net_rand_state);
-
- prandom_bytes_state(state, buf, bytes);
- put_cpu_var(net_rand_state);
-}
-EXPORT_SYMBOL(prandom_bytes);
-
static void prandom_warmup(struct rnd_state *state)
{
/* Calling RNG ten times to satisfy recurrence condition */
@@ -150,96 +107,6 @@ static void prandom_warmup(struct rnd_state *state)
prandom_u32_state(state);
}
-static u32 __extract_hwseed(void)
-{
- 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);
-}
-
-/**
- * prandom_seed - add entropy to pseudo random number generator
- * @entropy: entropy value
- *
- * Add some additional entropy to the prandom pool.
- */
-void prandom_seed(u32 entropy)
-{
- int i;
- /*
- * No locking on the CPUs, but then somewhat random results are, well,
- * expected.
- */
- for_each_possible_cpu(i) {
- struct rnd_state *state = &per_cpu(net_rand_state, i);
-
- state->s1 = __seed(state->s1 ^ entropy, 2U);
- prandom_warmup(state);
- }
-}
-EXPORT_SYMBOL(prandom_seed);
-
-/*
- * Generate some initially weak seeding values to allow
- * to start the prandom_u32() engine.
- */
-static int __init prandom_init(void)
-{
- int i;
-
- prandom_state_selftest();
-
- 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_early(state, weak_seed, true);
- prandom_warmup(state);
- }
-
- return 0;
-}
-core_initcall(prandom_init);
-
-static void __prandom_timer(struct timer_list *unused);
-
-static DEFINE_TIMER(seed_timer, __prandom_timer);
-
-static void __prandom_timer(struct timer_list *unused)
-{
- u32 entropy;
- unsigned long expires;
-
- get_random_bytes(&entropy, sizeof(entropy));
- prandom_seed(entropy);
-
- /* reseed every ~60 seconds, in [40 .. 80) interval with slack */
- expires = 40 + prandom_u32_max(40);
- seed_timer.expires = jiffies + msecs_to_jiffies(expires * MSEC_PER_SEC);
-
- add_timer(&seed_timer);
-}
-
-static void __init __prandom_start_seed_timer(void)
-{
- seed_timer.expires = jiffies + msecs_to_jiffies(40 * MSEC_PER_SEC);
- add_timer(&seed_timer);
-}
-
void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state)
{
int i;
@@ -259,51 +126,6 @@ void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state)
}
EXPORT_SYMBOL(prandom_seed_full_state);
-/*
- * Generate better values after random number generator
- * is fully initialized.
- */
-static void __prandom_reseed(bool late)
-{
- unsigned long flags;
- 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 */
- if (!spin_trylock_irqsave(&lock, flags))
- return;
-
- if (latch && !late)
- goto out;
-
- latch = true;
- prandom_seed_full_state(&net_rand_state);
-out:
- spin_unlock_irqrestore(&lock, flags);
-}
-
-void prandom_reseed_late(void)
-{
- __prandom_reseed(true);
-}
-
-static int __init prandom_reseed(void)
-{
- __prandom_reseed(false);
- __prandom_start_seed_timer();
- return 0;
-}
-late_initcall(prandom_reseed);
-
#ifdef CONFIG_RANDOM32_SELFTEST
static struct prandom_test1 {
u32 seed;
@@ -423,7 +245,28 @@ static struct prandom_test2 {
{ 407983964U, 921U, 728767059U },
};
-static void __init prandom_state_selftest(void)
+static u32 __extract_hwseed(void)
+{
+ 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);
+}
+
+static int __init prandom_state_selftest(void)
{
int i, j, errors = 0, runs = 0;
bool error = false;
@@ -463,5 +306,327 @@ static void __init prandom_state_selftest(void)
pr_warn("prandom: %d/%d self tests failed\n", errors, runs);
else
pr_info("prandom: %d self tests passed\n", runs);
+ return 0;
}
+core_initcall(prandom_state_selftest);
#endif
+
+/*
+ * The prandom_u32() implementation is now completely separate from the
+ * prandom_state() functions, which are retained (for now) for compatibility.
+ *
+ * Because of (ab)use in the networking code for choosing random TCP/UDP port
+ * numbers, which open DoS possibilities if guessable, we want something
+ * stronger than a standard PRNG. But the performance requirements of
+ * the network code do not allow robust crypto for this application.
+ *
+ * So this is a homebrew Junior Spaceman implementation, based on the
+ * lowest-latency trustworthy crypto primitive available, SipHash.
+ * (The authors of SipHash have not been consulted about this abuse of
+ * their work.)
+ *
+ * Standard SipHash-2-4 uses 2n+4 rounds to hash n words of input to
+ * one word of output. This abbreviated version uses 2 rounds per word
+ * of output.
+ */
+
+struct siprand_state {
+ unsigned long v0;
+ unsigned long v1;
+ unsigned long v2;
+ unsigned long v3;
+};
+
+static DEFINE_PER_CPU(struct siprand_state, net_rand_state) __latent_entropy;
+DEFINE_PER_CPU(unsigned long, net_rand_noise);
+EXPORT_PER_CPU_SYMBOL(net_rand_noise);
+
+/*
+ * This is the core CPRNG function. As "pseudorandom", this is not used
+ * for truly valuable things, just intended to be a PITA to guess.
+ * For maximum speed, we do just two SipHash rounds per word. This is
+ * the same rate as 4 rounds per 64 bits that SipHash normally uses,
+ * so hopefully it's reasonably secure.
+ *
+ * There are two changes from the official SipHash finalization:
+ * - We omit some constants XORed with v2 in the SipHash spec as irrelevant;
+ * they are there only to make the output rounds distinct from the input
+ * rounds, and this application has no input rounds.
+ * - Rather than returning v0^v1^v2^v3, return v1+v3.
+ * If you look at the SipHash round, the last operation on v3 is
+ * "v3 ^= v0", so "v0 ^ v3" just undoes that, a waste of time.
+ * Likewise "v1 ^= v2". (The rotate of v2 makes a difference, but
+ * it still cancels out half of the bits in v2 for no benefit.)
+ * Second, since the last combining operation was xor, continue the
+ * pattern of alternating xor/add for a tiny bit of extra non-linearity.
+ */
+static inline u32 siprand_u32(struct siprand_state *s)
+{
+ unsigned long v0 = s->v0, v1 = s->v1, v2 = s->v2, v3 = s->v3;
+ unsigned long n = raw_cpu_read(net_rand_noise);
+
+ v3 ^= n;
+ PRND_SIPROUND(v0, v1, v2, v3);
+ PRND_SIPROUND(v0, v1, v2, v3);
+ v0 ^= n;
+ s->v0 = v0; s->v1 = v1; s->v2 = v2; s->v3 = v3;
+ return v1 + v3;
+}
+
+
+/**
+ * prandom_u32 - pseudo random number generator
+ *
+ * A 32 bit pseudo-random number is generated using a fast
+ * algorithm suitable for simulation. This algorithm is NOT
+ * considered safe for cryptographic use.
+ */
+u32 prandom_u32(void)
+{
+ struct siprand_state *state = get_cpu_ptr(&net_rand_state);
+ u32 res = siprand_u32(state);
+
+ trace_prandom_u32(res);
+ put_cpu_ptr(&net_rand_state);
+ return res;
+}
+EXPORT_SYMBOL(prandom_u32);
+
+/**
+ * prandom_bytes - get the requested number of pseudo-random bytes
+ * @buf: where to copy the pseudo-random bytes to
+ * @bytes: the requested number of bytes
+ */
+void prandom_bytes(void *buf, size_t bytes)
+{
+ struct siprand_state *state = get_cpu_ptr(&net_rand_state);
+ u8 *ptr = buf;
+
+ while (bytes >= sizeof(u32)) {
+ put_unaligned(siprand_u32(state), (u32 *)ptr);
+ ptr += sizeof(u32);
+ bytes -= sizeof(u32);
+ }
+
+ if (bytes > 0) {
+ u32 rem = siprand_u32(state);
+
+ do {
+ *ptr++ = (u8)rem;
+ rem >>= BITS_PER_BYTE;
+ } while (--bytes > 0);
+ }
+ put_cpu_ptr(&net_rand_state);
+}
+EXPORT_SYMBOL(prandom_bytes);
+
+/**
+ * prandom_seed - add entropy to pseudo random number generator
+ * @entropy: entropy value
+ *
+ * Add some additional seed material to the prandom pool.
+ * The "entropy" is actually our IP address (the only caller is
+ * the network code), not for unpredictability, but to ensure that
+ * different machines are initialized differently.
+ */
+void prandom_seed(u32 entropy)
+{
+ int i;
+
+ add_device_randomness(&entropy, sizeof(entropy));
+
+ for_each_possible_cpu(i) {
+ struct siprand_state *state = per_cpu_ptr(&net_rand_state, i);
+ unsigned long v0 = state->v0, v1 = state->v1;
+ unsigned long v2 = state->v2, v3 = state->v3;
+
+ do {
+ v3 ^= entropy;
+ PRND_SIPROUND(v0, v1, v2, v3);
+ PRND_SIPROUND(v0, v1, v2, v3);
+ v0 ^= entropy;
+ } while (unlikely(!v0 || !v1 || !v2 || !v3));
+
+ WRITE_ONCE(state->v0, v0);
+ WRITE_ONCE(state->v1, v1);
+ WRITE_ONCE(state->v2, v2);
+ WRITE_ONCE(state->v3, v3);
+ }
+}
+EXPORT_SYMBOL(prandom_seed);
+
+/*
+ * Generate some initially weak seeding values to allow
+ * the prandom_u32() engine to be started.
+ */
+static int __init prandom_init_early(void)
+{
+ int i;
+ unsigned long v0, v1, v2, v3;
+
+ if (!arch_get_random_long(&v0))
+ v0 = jiffies;
+ if (!arch_get_random_long(&v1))
+ v1 = random_get_entropy();
+ v2 = v0 ^ PRND_K0;
+ v3 = v1 ^ PRND_K1;
+
+ for_each_possible_cpu(i) {
+ struct siprand_state *state;
+
+ v3 ^= i;
+ PRND_SIPROUND(v0, v1, v2, v3);
+ PRND_SIPROUND(v0, v1, v2, v3);
+ v0 ^= i;
+
+ state = per_cpu_ptr(&net_rand_state, i);
+ state->v0 = v0; state->v1 = v1;
+ state->v2 = v2; state->v3 = v3;
+ }
+
+ return 0;
+}
+core_initcall(prandom_init_early);
+
+
+/* Stronger reseeding when available, and periodically thereafter. */
+static void prandom_reseed(struct timer_list *unused);
+
+static DEFINE_TIMER(seed_timer, prandom_reseed);
+
+static void prandom_reseed(struct timer_list *unused)
+{
+ unsigned long expires;
+ int i;
+
+ /*
+ * Reinitialize each CPU's PRNG with 128 bits of key.
+ * No locking on the CPUs, but then somewhat random results are,
+ * well, expected.
+ */
+ for_each_possible_cpu(i) {
+ struct siprand_state *state;
+ unsigned long v0 = get_random_long(), v2 = v0 ^ PRND_K0;
+ unsigned long v1 = get_random_long(), v3 = v1 ^ PRND_K1;
+#if BITS_PER_LONG == 32
+ int j;
+
+ /*
+ * On 32-bit machines, hash in two extra words to
+ * approximate 128-bit key length. Not that the hash
+ * has that much security, but this prevents a trivial
+ * 64-bit brute force.
+ */
+ for (j = 0; j < 2; j++) {
+ unsigned long m = get_random_long();
+
+ v3 ^= m;
+ PRND_SIPROUND(v0, v1, v2, v3);
+ PRND_SIPROUND(v0, v1, v2, v3);
+ v0 ^= m;
+ }
+#endif
+ /*
+ * Probably impossible in practice, but there is a
+ * theoretical risk that a race between this reseeding
+ * and the target CPU writing its state back could
+ * create the all-zero SipHash fixed point.
+ *
+ * To ensure that never happens, ensure the state
+ * we write contains no zero words.
+ */
+ state = per_cpu_ptr(&net_rand_state, i);
+ WRITE_ONCE(state->v0, v0 ? v0 : -1ul);
+ WRITE_ONCE(state->v1, v1 ? v1 : -1ul);
+ WRITE_ONCE(state->v2, v2 ? v2 : -1ul);
+ WRITE_ONCE(state->v3, v3 ? v3 : -1ul);
+ }
+
+ /* reseed every ~60 seconds, in [40 .. 80) interval with slack */
+ expires = round_jiffies(jiffies + 40 * HZ + prandom_u32_max(40 * HZ));
+ mod_timer(&seed_timer, expires);
+}
+
+/*
+ * The random ready callback can be called from almost any interrupt.
+ * To avoid worrying about whether it's safe to delay that interrupt
+ * long enough to seed all CPUs, just schedule an immediate timer event.
+ */
+static void prandom_timer_start(struct random_ready_callback *unused)
+{
+ mod_timer(&seed_timer, jiffies);
+}
+
+#ifdef CONFIG_RANDOM32_SELFTEST
+/* Principle: True 32-bit random numbers will all have 16 differing bits on
+ * average. For each 32-bit number, there are 601M numbers differing by 16
+ * bits, and 89% of the numbers differ by at least 12 bits. Note that more
+ * than 16 differing bits also implies a correlation with inverted bits. Thus
+ * we take 1024 random numbers and compare each of them to the other ones,
+ * counting the deviation of correlated bits to 16. Constants report 32,
+ * counters 32-log2(TEST_SIZE), and pure randoms, around 6 or lower. With the
+ * u32 total, TEST_SIZE may be as large as 4096 samples.
+ */
+#define TEST_SIZE 1024
+static int __init prandom32_state_selftest(void)
+{
+ unsigned int x, y, bits, samples;
+ u32 xor, flip;
+ u32 total;
+ u32 *data;
+
+ data = kmalloc(sizeof(*data) * TEST_SIZE, GFP_KERNEL);
+ if (!data)
+ return 0;
+
+ for (samples = 0; samples < TEST_SIZE; samples++)
+ data[samples] = prandom_u32();
+
+ flip = total = 0;
+ for (x = 0; x < samples; x++) {
+ for (y = 0; y < samples; y++) {
+ if (x == y)
+ continue;
+ xor = data[x] ^ data[y];
+ flip |= xor;
+ bits = hweight32(xor);
+ total += (bits - 16) * (bits - 16);
+ }
+ }
+
+ /* We'll return the average deviation as 2*sqrt(corr/samples), which
+ * is also sqrt(4*corr/samples) which provides a better resolution.
+ */
+ bits = int_sqrt(total / (samples * (samples - 1)) * 4);
+ if (bits > 6)
+ pr_warn("prandom32: self test failed (at least %u bits"
+ " correlated, fixed_mask=%#x fixed_value=%#x\n",
+ bits, ~flip, data[0] & ~flip);
+ else
+ pr_info("prandom32: self test passed (less than %u bits"
+ " correlated)\n",
+ bits+1);
+ kfree(data);
+ return 0;
+}
+core_initcall(prandom32_state_selftest);
+#endif /* CONFIG_RANDOM32_SELFTEST */
+
+/*
+ * Start periodic full reseeding as soon as strong
+ * random numbers are available.
+ */
+static int __init prandom_init_late(void)
+{
+ static struct random_ready_callback random_ready = {
+ .func = prandom_timer_start
+ };
+ int ret = add_random_ready_callback(&random_ready);
+
+ if (ret == -EALREADY) {
+ prandom_timer_start(&random_ready);
+ ret = 0;
+ }
+ return ret;
+}
+late_initcall(prandom_init_late);
diff --git a/net/core/dev.c b/net/core/dev.c
index 9499a414d67e1021f976b31579ecbad9920044c0..82dc6b48e45fdff2dd117e6ff23bccad480aa612 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -145,6 +145,7 @@
#include <linux/indirect_call_wrapper.h>
#include <net/devlink.h>
#include <linux/pm_runtime.h>
+#include <linux/prandom.h>
#include "net-sysfs.h"
@@ -3558,6 +3559,7 @@ static int xmit_one(struct sk_buff *skb, struct net_device *dev,
dev_queue_xmit_nit(skb, dev);
len = skb->len;
+ PRANDOM_ADD_NOISE(skb, dev, txq, len + jiffies);
trace_net_dev_start_xmit(skb, dev);
rc = netdev_start_xmit(skb, dev, txq, more);
trace_net_dev_xmit(skb, rc, dev, len);
@@ -4130,6 +4132,7 @@ static int __dev_queue_xmit(struct sk_buff *skb, struct net_device *sb_dev)
if (!skb)
goto out;
+ PRANDOM_ADD_NOISE(skb, dev, txq, jiffies);
HARD_TX_LOCK(dev, txq, cpu);
if (!netif_xmit_stopped(txq)) {
@@ -4195,6 +4198,7 @@ int dev_direct_xmit(struct sk_buff *skb, u16 queue_id)
skb_set_queue_mapping(skb, queue_id);
txq = skb_get_tx_queue(dev, skb);
+ PRANDOM_ADD_NOISE(skb, dev, txq, jiffies);
local_bh_disable();