When we're just reading EX_CALLBACK data just get a read lock

The crypto_ex_data code was always obtaining a write lock in all functions
regardless of whether we were only reading EX_CALLBACK data or actually
changing it. Changes to the EX_CALLBACK data are rare, with many reads so
we should change to a read lock where we can.

We hit this every time we create or free any object that can have ex_data
associated with it (e.g. BIOs, SSL, etc)

Partially fixes #20286

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/20943)
This commit is contained in:
Matt Caswell 2023-05-11 11:25:07 +01:00
parent 7f2c22c1b9
commit 6d15357aeb

View File

@ -26,8 +26,10 @@ int ossl_do_ex_data_init(OSSL_LIB_CTX *ctx)
* Return the EX_CALLBACKS from the |ex_data| array that corresponds to
* a given class. On success, *holds the lock.*
* The |global| parameter is assumed to be non null (checked by the caller).
* If |read| is 1 then a read lock is obtained. Otherwise it is a write lock.
*/
static EX_CALLBACKS *get_and_lock(OSSL_EX_DATA_GLOBAL *global, int class_index)
static EX_CALLBACKS *get_and_lock(OSSL_EX_DATA_GLOBAL *global, int class_index,
int read)
{
EX_CALLBACKS *ip;
@ -44,8 +46,14 @@ static EX_CALLBACKS *get_and_lock(OSSL_EX_DATA_GLOBAL *global, int class_index)
return NULL;
}
if (!CRYPTO_THREAD_write_lock(global->ex_data_lock))
return NULL;
if (read) {
if (!CRYPTO_THREAD_read_lock(global->ex_data_lock))
return NULL;
} else {
if (!CRYPTO_THREAD_write_lock(global->ex_data_lock))
return NULL;
}
ip = &global->ex_data[class_index];
return ip;
}
@ -112,7 +120,7 @@ int ossl_crypto_free_ex_index_ex(OSSL_LIB_CTX *ctx, int class_index, int idx)
if (global == NULL)
return 0;
ip = get_and_lock(global, class_index);
ip = get_and_lock(global, class_index, 0);
if (ip == NULL)
return 0;
@ -153,7 +161,7 @@ int ossl_crypto_get_ex_new_index_ex(OSSL_LIB_CTX *ctx, int class_index,
if (global == NULL)
return -1;
ip = get_and_lock(global, class_index);
ip = get_and_lock(global, class_index, 0);
if (ip == NULL)
return -1;
@ -219,7 +227,7 @@ int ossl_crypto_new_ex_data_ex(OSSL_LIB_CTX *ctx, int class_index, void *obj,
if (global == NULL)
return 0;
ip = get_and_lock(global, class_index);
ip = get_and_lock(global, class_index, 1);
if (ip == NULL)
return 0;
@ -280,7 +288,7 @@ int CRYPTO_dup_ex_data(int class_index, CRYPTO_EX_DATA *to,
if (global == NULL)
return 0;
ip = get_and_lock(global, class_index);
ip = get_and_lock(global, class_index, 1);
if (ip == NULL)
return 0;
@ -367,7 +375,7 @@ void CRYPTO_free_ex_data(int class_index, void *obj, CRYPTO_EX_DATA *ad)
if (global == NULL)
goto err;
ip = get_and_lock(global, class_index);
ip = get_and_lock(global, class_index, 1);
if (ip == NULL)
goto err;
@ -434,7 +442,7 @@ int ossl_crypto_alloc_ex_data_intern(int class_index, void *obj,
if (global == NULL)
return 0;
ip = get_and_lock(global, class_index);
ip = get_and_lock(global, class_index, 1);
if (ip == NULL)
return 0;
f = sk_EX_CALLBACK_value(ip->meth, idx);