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Date: Mon, 30 May 2016 01:39:21 -0400
From: Theodore Ts'o <tytso@....edu>
To: Linux Kernel Developers List <linux-kernel@...r.kernel.org>
Cc: smueller@...onox.de, herbert@...dor.apana.org.au,
andi@...stfloor.org, sandyinchina@...il.com,
cryptography@...edaemon.net, jsd@...n.com, hpa@...or.com,
linux-crypto@...r.kernel.org, Theodore Ts'o <tytso@....edu>
Subject: [PATCH 1/5] 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: Theodore Ts'o <tytso@....edu>
---
crypto/chacha20_generic.c | 61 --------
drivers/char/random.c | 350 ++++++++++++++++++++++++++++++++++------------
include/crypto/chacha20.h | 1 +
lib/Makefile | 2 +-
lib/chacha20.c | 79 +++++++++++
5 files changed, 340 insertions(+), 153 deletions(-)
create mode 100644 lib/chacha20.c
diff --git a/crypto/chacha20_generic.c b/crypto/chacha20_generic.c
index da9c899..1cab831 100644
--- a/crypto/chacha20_generic.c
+++ b/crypto/chacha20_generic.c
@@ -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)
{
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 0158d3b..3a4d865 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -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 +414,29 @@ 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
+ * 2 --> Initialized
+ * 3 --> Initialized from input_pool
+ *
+ * crng_init is protected by primary_crng->lock, and only increases
+ * its value (from 0->1->2->3).
+ */
+static int crng_init = 0;
+#define crng_ready() (likely(crng_init >= 2))
+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 +466,15 @@ 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 +495,6 @@ 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 +697,6 @@ retry:
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 +706,27 @@ retry:
if (r == &input_pool) {
int entropy_bits = entropy_count >> ENTROPY_SHIFT;
+ if (crng_init < 3 && 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;
}
}
@@ -736,6 +746,157 @@ static void credit_entropy_bits_safe(struct entropy_store *r, int nbits)
/*********************************************************************
*
+ * CRNG using CHACHA20
+ *
+ *********************************************************************/
+
+#define CRNG_RESEED_INTERVAL (300*HZ)
+
+static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait);
+
+static void _initialize_crng(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 void initialize_crng(struct crng_state *crng)
+{
+ _initialize_crng(crng);
+ spin_lock_init(&crng->lock);
+}
+
+static int crng_fast_load(__u32 pool[4])
+{
+ int i;
+ __u32 *p;
+
+ if (!spin_trylock(&primary_crng.lock))
+ return 0;
+ if (crng_ready()) {
+ spin_unlock(&primary_crng.lock);
+ return 0;
+ }
+ p = &primary_crng.state[4];
+ if (crng_init == 1)
+ p += 4;
+ for (i=0; i < 4; i++)
+ *p ^= pool[i];
+ if (++crng_init >= 2) {
+ wake_up_interruptible(&crng_init_wait);
+ pr_notice("random: fast init done\n");
+ }
+ spin_unlock(&primary_crng.lock);
+ 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 < 3) {
+ crng_init = 3;
+ 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 > 2 &&
+ 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 +911,12 @@ 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 +928,6 @@ 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 +958,7 @@ 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));
/*
@@ -922,7 +1078,13 @@ void add_interrupt_randomness(int irq, int irq_flags)
!time_after(now, fast_pool->last + HZ))
return;
- r = nonblocking_pool.initialized ? &input_pool : &nonblocking_pool;
+ if (!crng_ready() && crng_fast_load(fast_pool->pool)) {
+ fast_pool->count = 0;
+ fast_pool->last = now;
+ return;
+ }
+
+ r = &input_pool;
if (!spin_trylock(&r->lock))
return;
@@ -965,9 +1127,6 @@ 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
@@ -1142,6 +1301,36 @@ 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.
@@ -1154,7 +1343,6 @@ 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;
@@ -1178,27 +1366,7 @@ 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);
}
/*
@@ -1253,15 +1421,26 @@ 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);
@@ -1279,7 +1458,7 @@ 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;
@@ -1287,7 +1466,7 @@ 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;
@@ -1351,7 +1530,7 @@ 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);
@@ -1396,7 +1575,7 @@ static int rand_initialize(void)
{
init_std_data(&input_pool);
init_std_data(&blocking_pool);
- init_std_data(&nonblocking_pool);
+ _initialize_crng(&primary_crng);
return 0;
}
early_initcall(rand_initialize);
@@ -1460,16 +1639,10 @@ urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
{
int ret;
- if (unlikely(nonblocking_pool.initialized == 0))
- printk_once(KERN_NOTICE "random: %s urandom read "
- "with %d bits of entropy available\n",
- current->comm, nonblocking_pool.entropy_total);
-
+ crng_wait_ready();
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;
}
@@ -1515,10 +1688,7 @@ 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;
@@ -1569,7 +1739,6 @@ 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:
@@ -1611,11 +1780,10 @@ 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;
}
diff --git a/include/crypto/chacha20.h b/include/crypto/chacha20.h
index 274bbae..20d20f68 100644
--- a/include/crypto/chacha20.h
+++ b/include/crypto/chacha20.h
@@ -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);
diff --git a/lib/Makefile b/lib/Makefile
index 499fb35..34e205f 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -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
diff --git a/lib/chacha20.c b/lib/chacha20.c
new file mode 100644
index 0000000..250ceed
--- /dev/null
+++ b/lib/chacha20.c
@@ -0,0 +1,79 @@
+/*
+ * 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);
--
2.5.0
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