random32: use real rng for non-deterministic randomness

diff --git a/include/linux/prandom.h b/include/linux/prandom.h
index a4aadd2dc153..77040efd77ef 100644
--- a/include/linux/prandom.h
+++ b/include/linux/prandom.h
@@ -10,53 +10,16 @@ 
 
 #include <linux/types.h>
 #include <linux/percpu.h>
-#include <linux/siphash.h>
+#include <linux/random.h>
 
-u32 prandom_u32(void);
-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) SIPHASH_PERMUTATION(v0, v1, v2, v3)
-
-#define PRND_K0 (SIPHASH_CONST_0 ^ SIPHASH_CONST_2)
-#define PRND_K1 (SIPHASH_CONST_1 ^ SIPHASH_CONST_3)
-
-#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) HSIPHASH_PERMUTATION(v0, v1, v2, v3)
-#define PRND_K0 (HSIPHASH_CONST_0 ^ HSIPHASH_CONST_2)
-#define PRND_K1 (HSIPHASH_CONST_1 ^ HSIPHASH_CONST_3)
-
-#else
-#error Unsupported BITS_PER_LONG
-#endif
+static inline u32 prandom_u32(void)
+{
+	return get_random_u32();
+}
 
-static inline void prandom_u32_add_noise(unsigned long a, unsigned long b,
-					 unsigned long c, unsigned long d)
+static inline void prandom_bytes(void *buf, size_t nbytes)
 {
-	/*
-	 * 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);
+	return get_random_bytes(buf, nbytes);
 }
 
 struct rnd_state {
@@ -70,6 +33,14 @@  void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state);
 #define prandom_init_once(pcpu_state)			\
 	DO_ONCE(prandom_seed_full_state, (pcpu_state))
 
+/*
+ * Handle minimum values for seeds
+ */
+static inline u32 __seed(u32 x, u32 m)
+{
+	return (x < m) ? x + m : x;
+}
+
 /**
  * prandom_u32_max - returns a pseudo-random number in interval [0, ep_ro)
  * @ep_ro: right open interval endpoint
@@ -87,14 +58,6 @@  static inline u32 prandom_u32_max(u32 ep_ro)
 	return (u32)(((u64) prandom_u32() * ep_ro) >> 32);
 }
 
-/*
- * Handle minimum values for seeds
- */
-static inline u32 __seed(u32 x, u32 m)
-{
-	return (x < m) ? x + m : x;
-}
-
 /**
  * prandom_seed_state - set seed for prandom_u32_state().
  * @state: pointer to state structure to receive the seed.
@@ -108,7 +71,6 @@  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 9dd2a39cb3b0..c12fe329c9ff 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1780,8 +1780,6 @@  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();
diff --git a/lib/random32.c b/lib/random32.c
index 976632003ec6..7aed7e7cf214 100644
--- a/lib/random32.c
+++ b/lib/random32.c
@@ -310,324 +310,3 @@  static int __init prandom_state_selftest(void)
 }
 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);
-
-	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 int prandom_timer_start(struct notifier_block *nb,
-			       unsigned long action, void *data)
-{
-	mod_timer(&seed_timer, jiffies);
-	return 0;
-}
-
-#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 notifier_block random_ready = {
-		.notifier_call = prandom_timer_start
-	};
-	int ret = register_random_ready_notifier(&random_ready);
-
-	if (ret == -EALREADY) {
-		prandom_timer_start(&random_ready, 0, NULL);
-		ret = 0;
-	}
-	return ret;
-}
-late_initcall(prandom_init_late);
diff --git a/net/core/dev.c b/net/core/dev.c
index 1461c2d9dec8..19c9beb1136b 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3527,7 +3527,6 @@  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);
@@ -4168,7 +4167,6 @@  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)) {
@@ -4234,7 +4232,6 @@  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();
 
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 53a6b14dc50a..3d6d33ac20cc 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -536,10 +536,8 @@  static int __inet_insert_ifa(struct in_ifaddr *ifa, struct nlmsghdr *nlh,
 		return ret;
 	}
 
-	if (!(ifa->ifa_flags & IFA_F_SECONDARY)) {
-		prandom_seed((__force u32) ifa->ifa_local);
+	if (!(ifa->ifa_flags & IFA_F_SECONDARY))
 		ifap = last_primary;
-	}
 
 	rcu_assign_pointer(ifa->ifa_next, *ifap);
 	rcu_assign_pointer(*ifap, ifa);
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index b22504176588..e7c68fa12fae 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -3972,8 +3972,6 @@  static void addrconf_dad_begin(struct inet6_ifaddr *ifp)
 
 	addrconf_join_solict(dev, &ifp->addr);
 
-	prandom_seed((__force u32) ifp->addr.s6_addr32[3]);
-
 	read_lock_bh(&idev->lock);
 	spin_lock(&ifp->lock);
 	if (ifp->state == INET6_IFADDR_STATE_DEAD)