[PATCH 4.9 059/264] random: remove the blocking pool

Greg Kroah-Hartman
2022-06-23T17:00:11Z

From: Andy Lutomirski <luto@kernel.org>

commit 90ea1c6436d26e62496616fb5891e00819ff4849 upstream.

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@kernel.org>
Link: https://lore.kernel.org/r/511225a224bf0a291149d3c0b8b45393cd03ab96.1577088521.git.luto@kernel.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 106 --------------------------------------------------
1 file changed, 106 deletions(-)

--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -471,7 +471,6 @@ 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;

@@ -533,7 +532,6 @@ struct entropy_store {
__u32 *pool;
const char *name;
struct entropy_store *pull;
- struct work_struct push_work;

/* read-write data: */
unsigned long last_pulled;
@@ -552,9 +550,7 @@ static ssize_t _extract_entropy(struct e
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],
@@ -563,16 +559,6 @@ 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 };
@@ -768,15 +754,11 @@ retry:
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);
}

@@ -785,7 +767,6 @@ retry:

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)
@@ -793,27 +774,6 @@ retry:
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);
}
}

@@ -1491,22 +1451,6 @@ static void _xfer_secondary_pool(struct
}

/*
- * 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.
*/
@@ -1684,54 +1628,6 @@ static ssize_t extract_entropy(struct en
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))

@@ -1961,7 +1857,6 @@ static void __init init_std_data(struct
int __init rand_initialize(void)
{
init_std_data(&input_pool);
- init_std_data(&blocking_pool);
if (crng_need_final_init)
crng_finalize_init(&primary_crng);
crng_initialize(&primary_crng);
@@ -2132,7 +2027,6 @@ static long random_ioctl(struct file *f,
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))