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Commit e192be9d authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

random: replace non-blocking pool with a Chacha20-based CRNG



The CRNG is faster, and we don't pretend to track entropy usage in the
CRNG any more.

Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent b1132dea
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+0 −61
Original line number Diff line number Diff line
@@ -15,72 +15,11 @@
#include <linux/module.h>
#include <crypto/chacha20.h>

static inline u32 rotl32(u32 v, u8 n)
{
	return (v << n) | (v >> (sizeof(v) * 8 - n));
}

static inline u32 le32_to_cpuvp(const void *p)
{
	return le32_to_cpup(p);
}

static void chacha20_block(u32 *state, void *stream)
{
	u32 x[16], *out = stream;
	int i;

	for (i = 0; i < ARRAY_SIZE(x); i++)
		x[i] = state[i];

	for (i = 0; i < 20; i += 2) {
		x[0]  += x[4];    x[12] = rotl32(x[12] ^ x[0],  16);
		x[1]  += x[5];    x[13] = rotl32(x[13] ^ x[1],  16);
		x[2]  += x[6];    x[14] = rotl32(x[14] ^ x[2],  16);
		x[3]  += x[7];    x[15] = rotl32(x[15] ^ x[3],  16);

		x[8]  += x[12];   x[4]  = rotl32(x[4]  ^ x[8],  12);
		x[9]  += x[13];   x[5]  = rotl32(x[5]  ^ x[9],  12);
		x[10] += x[14];   x[6]  = rotl32(x[6]  ^ x[10], 12);
		x[11] += x[15];   x[7]  = rotl32(x[7]  ^ x[11], 12);

		x[0]  += x[4];    x[12] = rotl32(x[12] ^ x[0],   8);
		x[1]  += x[5];    x[13] = rotl32(x[13] ^ x[1],   8);
		x[2]  += x[6];    x[14] = rotl32(x[14] ^ x[2],   8);
		x[3]  += x[7];    x[15] = rotl32(x[15] ^ x[3],   8);

		x[8]  += x[12];   x[4]  = rotl32(x[4]  ^ x[8],   7);
		x[9]  += x[13];   x[5]  = rotl32(x[5]  ^ x[9],   7);
		x[10] += x[14];   x[6]  = rotl32(x[6]  ^ x[10],  7);
		x[11] += x[15];   x[7]  = rotl32(x[7]  ^ x[11],  7);

		x[0]  += x[5];    x[15] = rotl32(x[15] ^ x[0],  16);
		x[1]  += x[6];    x[12] = rotl32(x[12] ^ x[1],  16);
		x[2]  += x[7];    x[13] = rotl32(x[13] ^ x[2],  16);
		x[3]  += x[4];    x[14] = rotl32(x[14] ^ x[3],  16);

		x[10] += x[15];   x[5]  = rotl32(x[5]  ^ x[10], 12);
		x[11] += x[12];   x[6]  = rotl32(x[6]  ^ x[11], 12);
		x[8]  += x[13];   x[7]  = rotl32(x[7]  ^ x[8],  12);
		x[9]  += x[14];   x[4]  = rotl32(x[4]  ^ x[9],  12);

		x[0]  += x[5];    x[15] = rotl32(x[15] ^ x[0],   8);
		x[1]  += x[6];    x[12] = rotl32(x[12] ^ x[1],   8);
		x[2]  += x[7];    x[13] = rotl32(x[13] ^ x[2],   8);
		x[3]  += x[4];    x[14] = rotl32(x[14] ^ x[3],   8);

		x[10] += x[15];   x[5]  = rotl32(x[5]  ^ x[10],  7);
		x[11] += x[12];   x[6]  = rotl32(x[6]  ^ x[11],  7);
		x[8]  += x[13];   x[7]  = rotl32(x[7]  ^ x[8],   7);
		x[9]  += x[14];   x[4]  = rotl32(x[4]  ^ x[9],   7);
	}

	for (i = 0; i < ARRAY_SIZE(x); i++)
		out[i] = cpu_to_le32(x[i] + state[i]);

	state[12]++;
}

static void chacha20_docrypt(u32 *state, u8 *dst, const u8 *src,
			     unsigned int bytes)
{
+276 −102
Original line number Diff line number Diff line
@@ -261,6 +261,7 @@
#include <linux/syscalls.h>
#include <linux/completion.h>
#include <linux/uuid.h>
#include <crypto/chacha20.h>

#include <asm/processor.h>
#include <asm/uaccess.h>
@@ -413,6 +414,31 @@ static struct fasync_struct *fasync;
static DEFINE_SPINLOCK(random_ready_list_lock);
static LIST_HEAD(random_ready_list);

struct crng_state {
	__u32		state[16];
	unsigned long	init_time;
	spinlock_t	lock;
};

struct crng_state primary_crng = {
	.lock = __SPIN_LOCK_UNLOCKED(primary_crng.lock),
};

/*
 * crng_init =  0 --> Uninitialized
 *		1 --> Initialized
 *		2 --> Initialized from input_pool
 *
 * crng_init is protected by primary_crng->lock, and only increases
 * its value (from 0->1->2).
 */
static int crng_init = 0;
#define crng_ready() (likely(crng_init > 0))
static int crng_init_cnt = 0;
#define CRNG_INIT_CNT_THRESH (2*CHACHA20_KEY_SIZE)
static void extract_crng(__u8 out[CHACHA20_BLOCK_SIZE]);
static void process_random_ready_list(void);

/**********************************************************************
 *
 * OS independent entropy store.   Here are the functions which handle
@@ -442,10 +468,15 @@ struct entropy_store {
	__u8 last_data[EXTRACT_SIZE];
};

static ssize_t extract_entropy(struct entropy_store *r, void *buf,
			       size_t nbytes, int min, int rsvd);
static ssize_t _extract_entropy(struct entropy_store *r, void *buf,
				size_t nbytes, int fips);

static void crng_reseed(struct crng_state *crng, struct entropy_store *r);
static void push_to_pool(struct work_struct *work);
static __u32 input_pool_data[INPUT_POOL_WORDS];
static __u32 blocking_pool_data[OUTPUT_POOL_WORDS];
static __u32 nonblocking_pool_data[OUTPUT_POOL_WORDS];

static struct entropy_store input_pool = {
	.poolinfo = &poolinfo_table[0],
@@ -466,16 +497,6 @@ static struct entropy_store blocking_pool = {
					push_to_pool),
};

static struct entropy_store nonblocking_pool = {
	.poolinfo = &poolinfo_table[1],
	.name = "nonblocking",
	.pull = &input_pool,
	.lock = __SPIN_LOCK_UNLOCKED(nonblocking_pool.lock),
	.pool = nonblocking_pool_data,
	.push_work = __WORK_INITIALIZER(nonblocking_pool.push_work,
					push_to_pool),
};

static __u32 const twist_table[8] = {
	0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158,
	0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 };
@@ -678,12 +699,6 @@ static void credit_entropy_bits(struct entropy_store *r, int nbits)
	if (!r->initialized && r->entropy_total > 128) {
		r->initialized = 1;
		r->entropy_total = 0;
		if (r == &nonblocking_pool) {
			prandom_reseed_late();
			process_random_ready_list();
			wake_up_all(&urandom_init_wait);
			pr_notice("random: %s pool is initialized\n", r->name);
		}
	}

	trace_credit_entropy_bits(r->name, nbits,
@@ -693,30 +708,27 @@ static void credit_entropy_bits(struct entropy_store *r, int nbits)
	if (r == &input_pool) {
		int entropy_bits = entropy_count >> ENTROPY_SHIFT;

		if (crng_init < 2 && entropy_bits >= 128) {
			crng_reseed(&primary_crng, r);
			entropy_bits = r->entropy_count >> ENTROPY_SHIFT;
		}

		/* should we wake readers? */
		if (entropy_bits >= random_read_wakeup_bits) {
			wake_up_interruptible(&random_read_wait);
			kill_fasync(&fasync, SIGIO, POLL_IN);
		}
		/* If the input pool is getting full, send some
		 * entropy to the two output pools, flipping back and
		 * forth between them, until the output pools are 75%
		 * full.
		 * entropy to the blocking pool until it is 75% full.
		 */
		if (entropy_bits > random_write_wakeup_bits &&
		    r->initialized &&
		    r->entropy_total >= 2*random_read_wakeup_bits) {
			static struct entropy_store *last = &blocking_pool;
			struct entropy_store *other = &blocking_pool;

			if (last == &blocking_pool)
				other = &nonblocking_pool;
			if (other->entropy_count <=
			    3 * other->poolinfo->poolfracbits / 4)
				last = other;
			if (last->entropy_count <=
			    3 * last->poolinfo->poolfracbits / 4) {
				schedule_work(&last->push_work);
			    3 * other->poolinfo->poolfracbits / 4) {
				schedule_work(&other->push_work);
				r->entropy_total = 0;
			}
		}
@@ -734,6 +746,152 @@ static void credit_entropy_bits_safe(struct entropy_store *r, int nbits)
	credit_entropy_bits(r, nbits);
}

/*********************************************************************
 *
 * CRNG using CHACHA20
 *
 *********************************************************************/

#define CRNG_RESEED_INTERVAL (300*HZ)

static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait);

static void crng_initialize(struct crng_state *crng)
{
	int		i;
	unsigned long	rv;

	memcpy(&crng->state[0], "expand 32-byte k", 16);
	if (crng == &primary_crng)
		_extract_entropy(&input_pool, &crng->state[4],
				 sizeof(__u32) * 12, 0);
	else
		get_random_bytes(&crng->state[4], sizeof(__u32) * 12);
	for (i = 4; i < 16; i++) {
		if (!arch_get_random_seed_long(&rv) &&
		    !arch_get_random_long(&rv))
			rv = random_get_entropy();
		crng->state[i] ^= rv;
	}
	crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1;
}

static int crng_fast_load(const char *cp, size_t len)
{
	unsigned long flags;
	char *p;

	if (!spin_trylock_irqsave(&primary_crng.lock, flags))
		return 0;
	if (crng_ready()) {
		spin_unlock_irqrestore(&primary_crng.lock, flags);
		return 0;
	}
	p = (unsigned char *) &primary_crng.state[4];
	while (len > 0 && crng_init_cnt < CRNG_INIT_CNT_THRESH) {
		p[crng_init_cnt % CHACHA20_KEY_SIZE] ^= *cp;
		cp++; crng_init_cnt++; len--;
	}
	if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) {
		crng_init = 1;
		wake_up_interruptible(&crng_init_wait);
		pr_notice("random: fast init done\n");
	}
	spin_unlock_irqrestore(&primary_crng.lock, flags);
	return 1;
}

static void crng_reseed(struct crng_state *crng, struct entropy_store *r)
{
	unsigned long	flags;
	int		i, num;
	union {
		__u8	block[CHACHA20_BLOCK_SIZE];
		__u32	key[8];
	} buf;

	if (r) {
		num = extract_entropy(r, &buf, 32, 16, 0);
		if (num == 0)
			return;
	} else
		extract_crng(buf.block);
	spin_lock_irqsave(&primary_crng.lock, flags);
	for (i = 0; i < 8; i++) {
		unsigned long	rv;
		if (!arch_get_random_seed_long(&rv) &&
		    !arch_get_random_long(&rv))
			rv = random_get_entropy();
		crng->state[i+4] ^= buf.key[i] ^ rv;
	}
	memzero_explicit(&buf, sizeof(buf));
	crng->init_time = jiffies;
	if (crng == &primary_crng && crng_init < 2) {
		crng_init = 2;
		process_random_ready_list();
		wake_up_interruptible(&crng_init_wait);
		pr_notice("random: crng init done\n");
	}
	spin_unlock_irqrestore(&primary_crng.lock, flags);
}

static inline void crng_wait_ready(void)
{
	wait_event_interruptible(crng_init_wait, crng_ready());
}

static void extract_crng(__u8 out[CHACHA20_BLOCK_SIZE])
{
	unsigned long v, flags;
	struct crng_state *crng = &primary_crng;

	if (crng_init > 1 &&
	    time_after(jiffies, crng->init_time + CRNG_RESEED_INTERVAL))
		crng_reseed(crng, &input_pool);
	spin_lock_irqsave(&crng->lock, flags);
	if (arch_get_random_long(&v))
		crng->state[14] ^= v;
	chacha20_block(&crng->state[0], out);
	if (crng->state[12] == 0)
		crng->state[13]++;
	spin_unlock_irqrestore(&crng->lock, flags);
}

static ssize_t extract_crng_user(void __user *buf, size_t nbytes)
{
	ssize_t ret = 0, i;
	__u8 tmp[CHACHA20_BLOCK_SIZE];
	int large_request = (nbytes > 256);

	while (nbytes) {
		if (large_request && need_resched()) {
			if (signal_pending(current)) {
				if (ret == 0)
					ret = -ERESTARTSYS;
				break;
			}
			schedule();
		}

		extract_crng(tmp);
		i = min_t(int, nbytes, CHACHA20_BLOCK_SIZE);
		if (copy_to_user(buf, tmp, i)) {
			ret = -EFAULT;
			break;
		}

		nbytes -= i;
		buf += i;
		ret += i;
	}

	/* Wipe data just written to memory */
	memzero_explicit(tmp, sizeof(tmp));

	return ret;
}


/*********************************************************************
 *
 * Entropy input management
@@ -750,12 +908,12 @@ struct timer_rand_state {
#define INIT_TIMER_RAND_STATE { INITIAL_JIFFIES, };

/*
 * Add device- or boot-specific data to the input and nonblocking
 * pools to help initialize them to unique values.
 * Add device- or boot-specific data to the input pool to help
 * initialize it.
 *
 * None of this adds any entropy, it is meant to avoid the
 * problem of the nonblocking pool having similar initial state
 * across largely identical devices.
 * None of this adds any entropy; it is meant to avoid the problem of
 * the entropy pool having similar initial state across largely
 * identical devices.
 */
void add_device_randomness(const void *buf, unsigned int size)
{
@@ -767,11 +925,6 @@ void add_device_randomness(const void *buf, unsigned int size)
	_mix_pool_bytes(&input_pool, buf, size);
	_mix_pool_bytes(&input_pool, &time, sizeof(time));
	spin_unlock_irqrestore(&input_pool.lock, flags);

	spin_lock_irqsave(&nonblocking_pool.lock, flags);
	_mix_pool_bytes(&nonblocking_pool, buf, size);
	_mix_pool_bytes(&nonblocking_pool, &time, sizeof(time));
	spin_unlock_irqrestore(&nonblocking_pool.lock, flags);
}
EXPORT_SYMBOL(add_device_randomness);

@@ -802,7 +955,7 @@ static void add_timer_randomness(struct timer_rand_state *state, unsigned num)
	sample.jiffies = jiffies;
	sample.cycles = random_get_entropy();
	sample.num = num;
	r = nonblocking_pool.initialized ? &input_pool : &nonblocking_pool;
	r = &input_pool;
	mix_pool_bytes(r, &sample, sizeof(sample));

	/*
@@ -918,11 +1071,21 @@ void add_interrupt_randomness(int irq, int irq_flags)
	fast_mix(fast_pool);
	add_interrupt_bench(cycles);

	if (!crng_ready()) {
		if ((fast_pool->count >= 64) &&
		    crng_fast_load((char *) fast_pool->pool,
				   sizeof(fast_pool->pool))) {
			fast_pool->count = 0;
			fast_pool->last = now;
		}
		return;
	}

	if ((fast_pool->count < 64) &&
	    !time_after(now, fast_pool->last + HZ))
		return;

	r = nonblocking_pool.initialized ? &input_pool : &nonblocking_pool;
	r = &input_pool;
	if (!spin_trylock(&r->lock))
		return;

@@ -966,9 +1129,6 @@ EXPORT_SYMBOL_GPL(add_disk_randomness);
 *
 *********************************************************************/

static ssize_t extract_entropy(struct entropy_store *r, void *buf,
			       size_t nbytes, int min, int rsvd);

/*
 * This utility inline function is responsible for transferring entropy
 * from the primary pool to the secondary extraction pool. We make
@@ -1143,6 +1303,36 @@ static void extract_buf(struct entropy_store *r, __u8 *out)
	memzero_explicit(&hash, sizeof(hash));
}

static ssize_t _extract_entropy(struct entropy_store *r, void *buf,
				size_t nbytes, int fips)
{
	ssize_t ret = 0, i;
	__u8 tmp[EXTRACT_SIZE];
	unsigned long flags;

	while (nbytes) {
		extract_buf(r, tmp);

		if (fips) {
			spin_lock_irqsave(&r->lock, flags);
			if (!memcmp(tmp, r->last_data, EXTRACT_SIZE))
				panic("Hardware RNG duplicated output!\n");
			memcpy(r->last_data, tmp, EXTRACT_SIZE);
			spin_unlock_irqrestore(&r->lock, flags);
		}
		i = min_t(int, nbytes, EXTRACT_SIZE);
		memcpy(buf, tmp, i);
		nbytes -= i;
		buf += i;
		ret += i;
	}

	/* Wipe data just returned from memory */
	memzero_explicit(tmp, sizeof(tmp));

	return ret;
}

/*
 * This function extracts randomness from the "entropy pool", and
 * returns it in a buffer.
@@ -1155,7 +1345,6 @@ static void extract_buf(struct entropy_store *r, __u8 *out)
static ssize_t extract_entropy(struct entropy_store *r, void *buf,
				 size_t nbytes, int min, int reserved)
{
	ssize_t ret = 0, i;
	__u8 tmp[EXTRACT_SIZE];
	unsigned long flags;

@@ -1179,27 +1368,7 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
	xfer_secondary_pool(r, nbytes);
	nbytes = account(r, nbytes, min, reserved);

	while (nbytes) {
		extract_buf(r, tmp);

		if (fips_enabled) {
			spin_lock_irqsave(&r->lock, flags);
			if (!memcmp(tmp, r->last_data, EXTRACT_SIZE))
				panic("Hardware RNG duplicated output!\n");
			memcpy(r->last_data, tmp, EXTRACT_SIZE);
			spin_unlock_irqrestore(&r->lock, flags);
		}
		i = min_t(int, nbytes, EXTRACT_SIZE);
		memcpy(buf, tmp, i);
		nbytes -= i;
		buf += i;
		ret += i;
	}

	/* Wipe data just returned from memory */
	memzero_explicit(tmp, sizeof(tmp));

	return ret;
	return _extract_entropy(r, buf, nbytes, fips_enabled);
}

/*
@@ -1254,15 +1423,26 @@ static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf,
 */
void get_random_bytes(void *buf, int nbytes)
{
	__u8 tmp[CHACHA20_BLOCK_SIZE];

#if DEBUG_RANDOM_BOOT > 0
	if (unlikely(nonblocking_pool.initialized == 0))
	if (!crng_ready())
		printk(KERN_NOTICE "random: %pF get_random_bytes called "
		       "with %d bits of entropy available\n",
		       (void *) _RET_IP_,
		       nonblocking_pool.entropy_total);
		       "with crng_init = %d\n", (void *) _RET_IP_, crng_init);
#endif
	trace_get_random_bytes(nbytes, _RET_IP_);
	extract_entropy(&nonblocking_pool, buf, nbytes, 0, 0);

	while (nbytes >= CHACHA20_BLOCK_SIZE) {
		extract_crng(buf);
		buf += CHACHA20_BLOCK_SIZE;
		nbytes -= CHACHA20_BLOCK_SIZE;
	}

	if (nbytes > 0) {
		extract_crng(tmp);
		memcpy(buf, tmp, nbytes);
		memzero_explicit(tmp, nbytes);
	}
}
EXPORT_SYMBOL(get_random_bytes);

@@ -1280,7 +1460,7 @@ int add_random_ready_callback(struct random_ready_callback *rdy)
	unsigned long flags;
	int err = -EALREADY;

	if (likely(nonblocking_pool.initialized))
	if (crng_ready())
		return err;

	owner = rdy->owner;
@@ -1288,7 +1468,7 @@ int add_random_ready_callback(struct random_ready_callback *rdy)
		return -ENOENT;

	spin_lock_irqsave(&random_ready_list_lock, flags);
	if (nonblocking_pool.initialized)
	if (crng_ready())
		goto out;

	owner = NULL;
@@ -1352,7 +1532,7 @@ void get_random_bytes_arch(void *buf, int nbytes)
	}

	if (nbytes)
		extract_entropy(&nonblocking_pool, p, nbytes, 0, 0);
		get_random_bytes(p, nbytes);
}
EXPORT_SYMBOL(get_random_bytes_arch);

@@ -1397,7 +1577,7 @@ static int rand_initialize(void)
{
	init_std_data(&input_pool);
	init_std_data(&blocking_pool);
	init_std_data(&nonblocking_pool);
	crng_initialize(&primary_crng);
	return 0;
}
early_initcall(rand_initialize);
@@ -1459,22 +1639,22 @@ random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
static ssize_t
urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
{
	unsigned long flags;
	static int maxwarn = 10;
	int ret;

	if (unlikely(nonblocking_pool.initialized == 0) &&
	    maxwarn > 0) {
	if (!crng_ready() && maxwarn > 0) {
		maxwarn--;
		printk(KERN_NOTICE "random: %s: uninitialized urandom read "
		       "(%zd bytes read, %d bits of entropy available)\n",
		       current->comm, nbytes, nonblocking_pool.entropy_total);
		       "(%zd bytes read)\n",
		       current->comm, nbytes);
		spin_lock_irqsave(&primary_crng.lock, flags);
		crng_init_cnt = 0;
		spin_unlock_irqrestore(&primary_crng.lock, flags);
	}

	nbytes = min_t(size_t, nbytes, INT_MAX >> (ENTROPY_SHIFT + 3));
	ret = extract_entropy_user(&nonblocking_pool, buf, nbytes);

	trace_urandom_read(8 * nbytes, ENTROPY_BITS(&nonblocking_pool),
			   ENTROPY_BITS(&input_pool));
	ret = extract_crng_user(buf, nbytes);
	trace_urandom_read(8 * nbytes, 0, ENTROPY_BITS(&input_pool));
	return ret;
}

@@ -1520,10 +1700,7 @@ static ssize_t random_write(struct file *file, const char __user *buffer,
{
	size_t ret;

	ret = write_pool(&blocking_pool, buffer, count);
	if (ret)
		return ret;
	ret = write_pool(&nonblocking_pool, buffer, count);
	ret = write_pool(&input_pool, buffer, count);
	if (ret)
		return ret;

@@ -1574,7 +1751,6 @@ static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
		if (!capable(CAP_SYS_ADMIN))
			return -EPERM;
		input_pool.entropy_count = 0;
		nonblocking_pool.entropy_count = 0;
		blocking_pool.entropy_count = 0;
		return 0;
	default:
@@ -1616,11 +1792,10 @@ SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count,
	if (flags & GRND_RANDOM)
		return _random_read(flags & GRND_NONBLOCK, buf, count);

	if (unlikely(nonblocking_pool.initialized == 0)) {
	if (!crng_ready()) {
		if (flags & GRND_NONBLOCK)
			return -EAGAIN;
		wait_event_interruptible(urandom_init_wait,
					 nonblocking_pool.initialized);
		crng_wait_ready();
		if (signal_pending(current))
			return -ERESTARTSYS;
	}
@@ -1856,18 +2031,17 @@ void add_hwgenerator_randomness(const char *buffer, size_t count,
{
	struct entropy_store *poolp = &input_pool;

	if (unlikely(nonblocking_pool.initialized == 0))
		poolp = &nonblocking_pool;
	else {
		/* Suspend writing if we're above the trickle
		 * threshold.  We'll be woken up again once below
		 * random_write_wakeup_thresh, or when the calling
		 * thread is about to terminate.
	if (!crng_ready()) {
		crng_fast_load(buffer, count);
		return;
	}

	/* Suspend writing if we're above the trickle threshold.
	 * We'll be woken up again once below random_write_wakeup_thresh,
	 * or when the calling thread is about to terminate.
	 */
		wait_event_interruptible(random_write_wait,
					 kthread_should_stop() ||
	wait_event_interruptible(random_write_wait, kthread_should_stop() ||
			ENTROPY_BITS(&input_pool) <= random_write_wakeup_bits);
	}
	mix_pool_bytes(poolp, buffer, count);
	credit_entropy_bits(poolp, entropy);
}
+1 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ struct chacha20_ctx {
	u32 key[8];
};

void chacha20_block(u32 *state, void *stream);
void crypto_chacha20_init(u32 *state, struct chacha20_ctx *ctx, u8 *iv);
int crypto_chacha20_setkey(struct crypto_tfm *tfm, const u8 *key,
			   unsigned int keysize);
+1 −1
Original line number Diff line number Diff line
@@ -22,7 +22,7 @@ KCOV_INSTRUMENT_hweight.o := n
lib-y := ctype.o string.o vsprintf.o cmdline.o \
	 rbtree.o radix-tree.o dump_stack.o timerqueue.o\
	 idr.o int_sqrt.o extable.o \
	 sha1.o md5.o irq_regs.o argv_split.o \
	 sha1.o chacha20.o md5.o irq_regs.o argv_split.o \
	 flex_proportions.o ratelimit.o show_mem.o \
	 is_single_threaded.o plist.o decompress.o kobject_uevent.o \
	 earlycpio.o seq_buf.o nmi_backtrace.o nodemask.o

lib/chacha20.c

0 → 100644
+79 −0
Original line number Diff line number Diff line
/*
 * ChaCha20 256-bit cipher algorithm, RFC7539
 *
 * Copyright (C) 2015 Martin Willi
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/bitops.h>
#include <linux/cryptohash.h>
#include <asm/unaligned.h>
#include <crypto/chacha20.h>

static inline u32 rotl32(u32 v, u8 n)
{
	return (v << n) | (v >> (sizeof(v) * 8 - n));
}

extern void chacha20_block(u32 *state, void *stream)
{
	u32 x[16], *out = stream;
	int i;

	for (i = 0; i < ARRAY_SIZE(x); i++)
		x[i] = state[i];

	for (i = 0; i < 20; i += 2) {
		x[0]  += x[4];    x[12] = rotl32(x[12] ^ x[0],  16);
		x[1]  += x[5];    x[13] = rotl32(x[13] ^ x[1],  16);
		x[2]  += x[6];    x[14] = rotl32(x[14] ^ x[2],  16);
		x[3]  += x[7];    x[15] = rotl32(x[15] ^ x[3],  16);

		x[8]  += x[12];   x[4]  = rotl32(x[4]  ^ x[8],  12);
		x[9]  += x[13];   x[5]  = rotl32(x[5]  ^ x[9],  12);
		x[10] += x[14];   x[6]  = rotl32(x[6]  ^ x[10], 12);
		x[11] += x[15];   x[7]  = rotl32(x[7]  ^ x[11], 12);

		x[0]  += x[4];    x[12] = rotl32(x[12] ^ x[0],   8);
		x[1]  += x[5];    x[13] = rotl32(x[13] ^ x[1],   8);
		x[2]  += x[6];    x[14] = rotl32(x[14] ^ x[2],   8);
		x[3]  += x[7];    x[15] = rotl32(x[15] ^ x[3],   8);

		x[8]  += x[12];   x[4]  = rotl32(x[4]  ^ x[8],   7);
		x[9]  += x[13];   x[5]  = rotl32(x[5]  ^ x[9],   7);
		x[10] += x[14];   x[6]  = rotl32(x[6]  ^ x[10],  7);
		x[11] += x[15];   x[7]  = rotl32(x[7]  ^ x[11],  7);

		x[0]  += x[5];    x[15] = rotl32(x[15] ^ x[0],  16);
		x[1]  += x[6];    x[12] = rotl32(x[12] ^ x[1],  16);
		x[2]  += x[7];    x[13] = rotl32(x[13] ^ x[2],  16);
		x[3]  += x[4];    x[14] = rotl32(x[14] ^ x[3],  16);

		x[10] += x[15];   x[5]  = rotl32(x[5]  ^ x[10], 12);
		x[11] += x[12];   x[6]  = rotl32(x[6]  ^ x[11], 12);
		x[8]  += x[13];   x[7]  = rotl32(x[7]  ^ x[8],  12);
		x[9]  += x[14];   x[4]  = rotl32(x[4]  ^ x[9],  12);

		x[0]  += x[5];    x[15] = rotl32(x[15] ^ x[0],   8);
		x[1]  += x[6];    x[12] = rotl32(x[12] ^ x[1],   8);
		x[2]  += x[7];    x[13] = rotl32(x[13] ^ x[2],   8);
		x[3]  += x[4];    x[14] = rotl32(x[14] ^ x[3],   8);

		x[10] += x[15];   x[5]  = rotl32(x[5]  ^ x[10],  7);
		x[11] += x[12];   x[6]  = rotl32(x[6]  ^ x[11],  7);
		x[8]  += x[13];   x[7]  = rotl32(x[7]  ^ x[8],   7);
		x[9]  += x[14];   x[4]  = rotl32(x[4]  ^ x[9],   7);
	}

	for (i = 0; i < ARRAY_SIZE(x); i++)
		out[i] = cpu_to_le32(x[i] + state[i]);

	state[12]++;
}
EXPORT_SYMBOL(chacha20_block);