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Date: Thu, 29 Aug 2019 18:11:40 -0700
From: Andy Lutomirski <luto@...nel.org>
To: Theodore Tso <tytso@...gle.com>
Cc: LKML <linux-kernel@...r.kernel.org>,
Linux API <linux-api@...r.kernel.org>,
Kees Cook <keescook@...omium.org>,
"Jason A. Donenfeld" <Jason@...c4.com>,
Andy Lutomirski <luto@...nel.org>
Subject: [PATCH 5/7] random: Remove the blocking pool
There is no longer any interface to read data from the blocking
pool, so remove it.
This enables quite a bit of code deletion, much of which will be
done in subsequent patches.
Signed-off-by: Andy Lutomirski <luto@...nel.org>
---
drivers/char/random.c | 106 ------------------------------------------
1 file changed, 106 deletions(-)
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 29a158d9353c..4521138231ed 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -470,7 +470,6 @@ static const struct poolinfo {
/*
* Static global variables
*/
-static DECLARE_WAIT_QUEUE_HEAD(random_read_wait);
static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
static struct fasync_struct *fasync;
@@ -530,7 +529,6 @@ struct entropy_store {
__u32 *pool;
const char *name;
struct entropy_store *pull;
- struct work_struct push_work;
/* read-write data: */
unsigned long last_pulled;
@@ -549,9 +547,7 @@ 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] __latent_entropy;
-static __u32 blocking_pool_data[OUTPUT_POOL_WORDS] __latent_entropy;
static struct entropy_store input_pool = {
.poolinfo = &poolinfo_table[0],
@@ -560,16 +556,6 @@ static struct entropy_store input_pool = {
.pool = input_pool_data
};
-static struct entropy_store blocking_pool = {
- .poolinfo = &poolinfo_table[1],
- .name = "blocking",
- .pull = &input_pool,
- .lock = __SPIN_LOCK_UNLOCKED(blocking_pool.lock),
- .pool = blocking_pool_data,
- .push_work = __WORK_INITIALIZER(blocking_pool.push_work,
- push_to_pool),
-};
-
static __u32 const twist_table[8] = {
0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158,
0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 };
@@ -765,15 +751,11 @@ static void credit_entropy_bits(struct entropy_store *r, int nbits)
entropy_count = 0;
} else if (entropy_count > pool_size)
entropy_count = pool_size;
- if ((r == &blocking_pool) && !r->initialized &&
- (entropy_count >> ENTROPY_SHIFT) > 128)
- has_initialized = 1;
if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
goto retry;
if (has_initialized) {
r->initialized = 1;
- wake_up_interruptible(&random_read_wait);
kill_fasync(&fasync, SIGIO, POLL_IN);
}
@@ -782,7 +764,6 @@ static void credit_entropy_bits(struct entropy_store *r, int nbits)
if (r == &input_pool) {
int entropy_bits = entropy_count >> ENTROPY_SHIFT;
- struct entropy_store *other = &blocking_pool;
if (crng_init < 2) {
if (entropy_bits < 128)
@@ -790,27 +771,6 @@ static void credit_entropy_bits(struct entropy_store *r, int nbits)
crng_reseed(&primary_crng, r);
entropy_bits = r->entropy_count >> ENTROPY_SHIFT;
}
-
- /* initialize the blocking pool if necessary */
- if (entropy_bits >= random_read_wakeup_bits &&
- !other->initialized) {
- schedule_work(&other->push_work);
- return;
- }
-
- /* should we wake readers? */
- if (entropy_bits >= random_read_wakeup_bits &&
- wq_has_sleeper(&random_read_wait)) {
- wake_up_interruptible(&random_read_wait);
- }
- /* If the input pool is getting full, and the blocking
- * pool has room, send some entropy to the blocking
- * pool.
- */
- if (!work_pending(&other->push_work) &&
- (ENTROPY_BITS(r) > 6 * r->poolinfo->poolbytes) &&
- (ENTROPY_BITS(other) <= 6 * other->poolinfo->poolbytes))
- schedule_work(&other->push_work);
}
}
@@ -1422,22 +1382,6 @@ static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
credit_entropy_bits(r, bytes*8);
}
-/*
- * Used as a workqueue function so that when the input pool is getting
- * full, we can "spill over" some entropy to the output pools. That
- * way the output pools can store some of the excess entropy instead
- * of letting it go to waste.
- */
-static void push_to_pool(struct work_struct *work)
-{
- struct entropy_store *r = container_of(work, struct entropy_store,
- push_work);
- BUG_ON(!r);
- _xfer_secondary_pool(r, random_read_wakeup_bits/8);
- trace_push_to_pool(r->name, r->entropy_count >> ENTROPY_SHIFT,
- r->pull->entropy_count >> ENTROPY_SHIFT);
-}
-
/*
* This function decides how many bytes to actually take from the
* given pool, and also debits the entropy count accordingly.
@@ -1616,54 +1560,6 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
return _extract_entropy(r, buf, nbytes, fips_enabled);
}
-/*
- * This function extracts randomness from the "entropy pool", and
- * returns it in a userspace buffer.
- */
-static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf,
- size_t nbytes)
-{
- ssize_t ret = 0, i;
- __u8 tmp[EXTRACT_SIZE];
- int large_request = (nbytes > 256);
-
- trace_extract_entropy_user(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_);
- if (!r->initialized && r->pull) {
- xfer_secondary_pool(r, ENTROPY_BITS(r->pull)/8);
- if (!r->initialized)
- return 0;
- }
- xfer_secondary_pool(r, nbytes);
- nbytes = account(r, nbytes, 0, 0);
-
- while (nbytes) {
- if (large_request && need_resched()) {
- if (signal_pending(current)) {
- if (ret == 0)
- ret = -ERESTARTSYS;
- break;
- }
- schedule();
- }
-
- extract_buf(r, tmp);
- i = min_t(int, nbytes, EXTRACT_SIZE);
- if (copy_to_user(buf, tmp, i)) {
- ret = -EFAULT;
- break;
- }
-
- nbytes -= i;
- buf += i;
- ret += i;
- }
-
- /* Wipe data just returned from memory */
- memzero_explicit(tmp, sizeof(tmp));
-
- return ret;
-}
-
#define warn_unseeded_randomness(previous) \
_warn_unseeded_randomness(__func__, (void *) _RET_IP_, (previous))
@@ -1893,7 +1789,6 @@ static void __init init_std_data(struct entropy_store *r)
int __init rand_initialize(void)
{
init_std_data(&input_pool);
- init_std_data(&blocking_pool);
crng_initialize(&primary_crng);
crng_global_init_time = jiffies;
if (ratelimit_disable) {
@@ -2053,7 +1948,6 @@ 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;
- blocking_pool.entropy_count = 0;
return 0;
case RNDRESEEDCRNG:
if (!capable(CAP_SYS_ADMIN))
--
2.21.0
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