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Convert rand code to new threading API
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Replace the CRYPTO_LOCK_RAND and CRYPTO_LOCK_RAND2 locks with new thread
API style locks.

Reviewed-by: Rich Salz <rsalz@openssl.org>
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@mattcaswell
mattcaswell committed Mar 9, 2016
1 parent 29eed3d commit 8eed7e8
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Showing 2 changed files with 47 additions and 34 deletions.
79 changes: 47 additions & 32 deletions crypto/rand/md_rand.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -125,6 +125,7 @@
#include <openssl/rand.h>
#include <openssl/async.h>
#include "rand_lcl.h"
#include "internal/threads.h"

#include <openssl/err.h>

Expand All @@ -147,12 +148,15 @@ static long md_count[2] = { 0, 0 };
static double entropy = 0;
static int initialized = 0;

static unsigned int crypto_lock_rand = 0; /* may be set only when a thread
* holds CRYPTO_LOCK_RAND (to
* prevent double locking) */
/* access to lockin_thread is synchronized by CRYPTO_LOCK_RAND2 */
static CRYPTO_RWLOCK *rand_lock = NULL;
static CRYPTO_RWLOCK *rand_tmp_lock = NULL;
static CRYPTO_ONCE rand_lock_init = CRYPTO_ONCE_STATIC_INIT;

/* May be set only when a thread holds rand_lock (to prevent double locking) */
static unsigned int crypto_lock_rand = 0;
/* access to locking_threadid is synchronized by rand_tmp_lock */
/* valid iff crypto_lock_rand is set */
static CRYPTO_THREADID locking_threadid;
static CRYPTO_THREAD_ID locking_threadid;

#ifdef PREDICT
int rand_predictable = 0;
Expand Down Expand Up @@ -183,6 +187,12 @@ static RAND_METHOD rand_meth = {
rand_status
};

static void do_rand_lock_init(void)
{
rand_lock = CRYPTO_THREAD_lock_new();
rand_tmp_lock = CRYPTO_THREAD_lock_new();
}

RAND_METHOD *RAND_OpenSSL(void)
{
return (&rand_meth);
Expand All @@ -198,6 +208,8 @@ static void rand_cleanup(void)
md_count[1] = 0;
entropy = 0;
initialized = 0;
CRYPTO_THREAD_lock_free(rand_lock);
CRYPTO_THREAD_lock_free(rand_tmp_lock);
}

static int rand_add(const void *buf, int num, double add)
Expand Down Expand Up @@ -231,18 +243,19 @@ static int rand_add(const void *buf, int num, double add)
if (m == NULL)
goto err;

CRYPTO_THREAD_run_once(&rand_lock_init, do_rand_lock_init);

/* check if we already have the lock */
if (crypto_lock_rand) {
CRYPTO_THREADID cur;
CRYPTO_THREADID_current(&cur);
CRYPTO_r_lock(CRYPTO_LOCK_RAND2);
do_not_lock = !CRYPTO_THREADID_cmp(&locking_threadid, &cur);
CRYPTO_r_unlock(CRYPTO_LOCK_RAND2);
CRYPTO_THREAD_ID cur = CRYPTO_THREAD_get_current_id();
CRYPTO_THREAD_read_lock(rand_tmp_lock);
do_not_lock = CRYPTO_THREAD_compare_id(locking_threadid, cur);
CRYPTO_THREAD_unlock(rand_tmp_lock);
} else
do_not_lock = 0;

if (!do_not_lock)
CRYPTO_w_lock(CRYPTO_LOCK_RAND);
CRYPTO_THREAD_write_lock(rand_lock);
st_idx = state_index;

/*
Expand Down Expand Up @@ -274,7 +287,7 @@ static int rand_add(const void *buf, int num, double add)
md_count[1] += (num / MD_DIGEST_LENGTH) + (num % MD_DIGEST_LENGTH > 0);

if (!do_not_lock)
CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
CRYPTO_THREAD_unlock(rand_lock);

for (i = 0; i < num; i += MD_DIGEST_LENGTH) {
j = (num - i);
Expand Down Expand Up @@ -328,7 +341,7 @@ static int rand_add(const void *buf, int num, double add)
}

if (!do_not_lock)
CRYPTO_w_lock(CRYPTO_LOCK_RAND);
CRYPTO_THREAD_write_lock(rand_lock);
/*
* Don't just copy back local_md into md -- this could mean that other
* thread's seeding remains without effect (except for the incremented
Expand All @@ -341,7 +354,7 @@ static int rand_add(const void *buf, int num, double add)
if (entropy < ENTROPY_NEEDED) /* stop counting when we have enough */
entropy += add;
if (!do_not_lock)
CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
CRYPTO_THREAD_unlock(rand_lock);

rv = 1;
err:
Expand Down Expand Up @@ -428,17 +441,18 @@ static int rand_bytes(unsigned char *buf, int num, int pseudo)
* global 'md'.
*/

CRYPTO_w_lock(CRYPTO_LOCK_RAND);
CRYPTO_THREAD_run_once(&rand_lock_init, do_rand_lock_init);
CRYPTO_THREAD_write_lock(rand_lock);
/*
* We could end up in an async engine while holding this lock so ensure
* we don't pause and cause a deadlock
*/
ASYNC_block_pause();

/* prevent rand_bytes() from trying to obtain the lock again */
CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
CRYPTO_THREADID_current(&locking_threadid);
CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
CRYPTO_THREAD_write_lock(rand_tmp_lock);
locking_threadid = CRYPTO_THREAD_get_current_id();
CRYPTO_THREAD_unlock(rand_tmp_lock);
crypto_lock_rand = 1;

if (!initialized) {
Expand Down Expand Up @@ -513,7 +527,7 @@ static int rand_bytes(unsigned char *buf, int num, int pseudo)
/* before unlocking, we must clear 'crypto_lock_rand' */
crypto_lock_rand = 0;
ASYNC_unblock_pause();
CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
CRYPTO_THREAD_unlock(rand_lock);

while (num > 0) {
/* num_ceil -= MD_DIGEST_LENGTH/2 */
Expand Down Expand Up @@ -566,17 +580,17 @@ static int rand_bytes(unsigned char *buf, int num, int pseudo)
|| !MD_Update(m, (unsigned char *)&(md_c[0]), sizeof(md_c))
|| !MD_Update(m, local_md, MD_DIGEST_LENGTH))
goto err;
CRYPTO_w_lock(CRYPTO_LOCK_RAND);
CRYPTO_THREAD_write_lock(rand_lock);
/*
* Prevent deadlocks if we end up in an async engine
*/
ASYNC_block_pause();
if (!MD_Update(m, md, MD_DIGEST_LENGTH) || !MD_Final(m, md)) {
CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
CRYPTO_THREAD_unlock(rand_lock);
goto err;
}
ASYNC_unblock_pause();
CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
CRYPTO_THREAD_unlock(rand_lock);

EVP_MD_CTX_free(m);
if (ok)
Expand Down Expand Up @@ -617,24 +631,25 @@ static int rand_pseudo_bytes(unsigned char *buf, int num)

static int rand_status(void)
{
CRYPTO_THREADID cur;
CRYPTO_THREAD_ID cur;
int ret;
int do_not_lock;

CRYPTO_THREADID_current(&cur);
CRYPTO_THREAD_run_once(&rand_lock_init, do_rand_lock_init);
cur = CRYPTO_THREAD_get_current_id();
/*
* check if we already have the lock (could happen if a RAND_poll()
* implementation calls RAND_status())
*/
if (crypto_lock_rand) {
CRYPTO_r_lock(CRYPTO_LOCK_RAND2);
do_not_lock = !CRYPTO_THREADID_cmp(&locking_threadid, &cur);
CRYPTO_r_unlock(CRYPTO_LOCK_RAND2);
CRYPTO_THREAD_read_lock(rand_tmp_lock);
do_not_lock = CRYPTO_THREAD_compare_id(locking_threadid, cur);
CRYPTO_THREAD_unlock(rand_tmp_lock);
} else
do_not_lock = 0;

if (!do_not_lock) {
CRYPTO_w_lock(CRYPTO_LOCK_RAND);
CRYPTO_THREAD_write_lock(rand_lock);
/*
* Prevent deadlocks in case we end up in an async engine
*/
Expand All @@ -643,9 +658,9 @@ static int rand_status(void)
/*
* prevent rand_bytes() from trying to obtain the lock again
*/
CRYPTO_w_lock(CRYPTO_LOCK_RAND2);
CRYPTO_THREADID_cpy(&locking_threadid, &cur);
CRYPTO_w_unlock(CRYPTO_LOCK_RAND2);
CRYPTO_THREAD_write_lock(rand_tmp_lock);
locking_threadid = cur;
CRYPTO_THREAD_unlock(rand_tmp_lock);
crypto_lock_rand = 1;
}

Expand All @@ -661,7 +676,7 @@ static int rand_status(void)
crypto_lock_rand = 0;

ASYNC_unblock_pause();
CRYPTO_w_unlock(CRYPTO_LOCK_RAND);
CRYPTO_THREAD_unlock(rand_lock);
}

return ret;
Expand Down
2 changes: 0 additions & 2 deletions include/openssl/crypto.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -166,8 +166,6 @@ extern "C" {
*/

# define CRYPTO_LOCK_X509_STORE 11
# define CRYPTO_LOCK_RAND 18
# define CRYPTO_LOCK_RAND2 19
# define CRYPTO_LOCK_DYNLOCK 29
# define CRYPTO_LOCK_ENGINE 30
# define CRYPTO_LOCK_ECDSA 32
Expand Down

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