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tests/drbgtest: use new RAND_DRBG callback_data API instead of ex_data 

It took me a little while to realize why the test_rand_drbg_reseed test
kept crashing after replacing the RAND_DRBG_{gs}et_ex_data() calls by
RAND_DRBG_{gs}et_callback_data().

The reason was that the ex_data API prohibits modifying the callbacks
or callback data of chained DRBGs and returned an error which was
ignored by the `test_rand_drbg_reseed` test, for good reasons.

The `test_rand_drbg_reseed` test is special in this respect, because
it needs to install callbacks for all DRBGs, in order to intercept
and count the reseeding events.

Since the drbgtest module has access to the internal structures of
the DRBG anyway, the problem could be solved by accessing the members
directly. I added a warning comment in hook_drbg().

[extended tests]

Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/10950)
This commit is contained in:
Dr. Matthias St. Pierre 2020-01-31 13:32:11 +01:00
parent 30a9d5d1a7
commit 09066cf2a1
2 changed files with 18 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
doc/man3/RAND_DRBG_set_callbacks.pod
View File

@ -62,7 +62,7 @@ RAND_DRBG_set_callback_data() can be used to store a pointer to some context
specific data, which can subsequently be retrieved by the entropy and nonce
callbacks using RAND_DRBG_get_callback_data().
The ownership of the context data remains with the caller, i.e., it is the
caller's responsibility to keep it available as long as it is need by the
caller's responsibility to keep it available as long as it is needed by the
callbacks and free it after use.
For more information about the the callback data see the NOTES section.
@ -140,7 +140,7 @@ In this case the DRBG will automatically request an extra amount of entropy
utilize for the nonce, following the recommendations of [NIST SP 800-90A Rev. 1],
section 8.6.7.
The callback data a rather specialized feature, because in general the
The callback data is a rather specialized feature, because in general the
random sources don't (and in fact, they must not) depend on any state provided
by the DRBG.
There are however exceptional cases where this feature is useful, most notably

31
test/drbgtest.c
View File

@ -127,8 +127,6 @@ static DRBG_SELFTEST_DATA drbg_test[] = {
make_drbg_test_data_hash(NID_sha512, sha512, 0),
};
static int app_data_index;
/*
* Test context data, attached as EXDATA to the RAND_DRBG
*/
@ -145,7 +143,7 @@ static size_t kat_entropy(RAND_DRBG *drbg, unsigned char **pout,
int entropy, size_t min_len, size_t max_len,
int prediction_resistance)
{
TEST_CTX *t = (TEST_CTX *)RAND_DRBG_get_ex_data(drbg, app_data_index);
TEST_CTX *t = (TEST_CTX *)RAND_DRBG_get_callback_data(drbg);
t->entropycnt++;
*pout = (unsigned char *)t->entropy;
@ -155,7 +153,7 @@ static size_t kat_entropy(RAND_DRBG *drbg, unsigned char **pout,
static size_t kat_nonce(RAND_DRBG *drbg, unsigned char **pout,
int entropy, size_t min_len, size_t max_len)
{
TEST_CTX *t = (TEST_CTX *)RAND_DRBG_get_ex_data(drbg, app_data_index);
TEST_CTX *t = (TEST_CTX *)RAND_DRBG_get_callback_data(drbg);
t->noncecnt++;
*pout = (unsigned char *)t->nonce;
@ -213,6 +211,7 @@ static int single_kat(DRBG_SELFTEST_DATA *td)
return 0;
if (!TEST_true(RAND_DRBG_set_callbacks(drbg, kat_entropy, NULL,
kat_nonce, NULL))
|| !TEST_true(RAND_DRBG_set_callback_data(drbg, &t))
|| !TEST_true(disable_crngt(drbg))) {
failures++;
goto err;
@ -222,7 +221,6 @@ static int single_kat(DRBG_SELFTEST_DATA *td)
t.entropylen = td->entropylen;
t.nonce = td->nonce;
t.noncelen = td->noncelen;
RAND_DRBG_set_ex_data(drbg, app_data_index, &t);
if (!TEST_true(RAND_DRBG_instantiate(drbg, td->pers, td->perslen))
|| !TEST_true(RAND_DRBG_generate(drbg, buff, td->exlen, 0,
@ -246,9 +244,9 @@ static int single_kat(DRBG_SELFTEST_DATA *td)
*/
if (!TEST_true(RAND_DRBG_set(drbg, td->nid, td->flags))
|| !TEST_true(RAND_DRBG_set_callbacks(drbg, kat_entropy, NULL,
kat_nonce, NULL)))
kat_nonce, NULL))
|| !TEST_true(RAND_DRBG_set_callback_data(drbg, &t)))
failures++;
RAND_DRBG_set_ex_data(drbg, app_data_index, &t);
t.entropy = td->entropy_pr;
t.entropylen = td->entropylen_pr;
t.nonce = td->nonce_pr;
@ -296,7 +294,7 @@ static int init(RAND_DRBG *drbg, DRBG_SELFTEST_DATA *td, TEST_CTX *t)
|| !TEST_true(RAND_DRBG_set_callbacks(drbg, kat_entropy, NULL,
kat_nonce, NULL)))
return 0;
RAND_DRBG_set_ex_data(drbg, app_data_index, t);
RAND_DRBG_set_callback_data(drbg, t);
t->entropy = td->entropy;
t->entropylen = td->entropylen;
t->nonce = td->nonce;
@ -551,7 +549,7 @@ static HOOK_CTX master_ctx, public_ctx, private_ctx;
static HOOK_CTX *get_hook_ctx(RAND_DRBG *drbg)
{
return (HOOK_CTX *)RAND_DRBG_get_ex_data(drbg, app_data_index);
return (HOOK_CTX *)RAND_DRBG_get_callback_data(drbg);
}
/* Intercepts and counts calls to the get_entropy() callback */
@ -579,17 +577,22 @@ static void hook_drbg(RAND_DRBG *drbg, HOOK_CTX *ctx)
memset(ctx, 0, sizeof(*ctx));
ctx->drbg = drbg;
ctx->get_entropy = drbg->get_entropy;
/*
* We can't use the public API here, since it prohibits modifying
* the callbacks or the callback data of chained DRBGs.
*/
drbg->get_entropy = get_entropy_hook;
RAND_DRBG_set_ex_data(drbg, app_data_index, ctx);
drbg->callback_data = ctx;
}
/* Installs the hook for the get_entropy() callback of the given drbg */
static void unhook_drbg(RAND_DRBG *drbg)
{
HOOK_CTX *ctx = get_hook_ctx(drbg);
HOOK_CTX *ctx = drbg->callback_data;
drbg->get_entropy = ctx->get_entropy;
CRYPTO_free_ex_data(CRYPTO_EX_INDEX_RAND_DRBG, drbg, &drbg->ex_data);
if (ctx != NULL)
drbg->get_entropy = ctx->get_entropy;
}
/* Resets the given hook context */
@ -1382,8 +1385,6 @@ err:
int setup_tests(void)
{
app_data_index = RAND_DRBG_get_ex_new_index(0L, NULL, NULL, NULL, NULL);
ADD_ALL_TESTS(test_kats, OSSL_NELEM(drbg_test));
ADD_ALL_TESTS(test_error_checks, OSSL_NELEM(drbg_test));
ADD_TEST(test_rand_drbg_reseed);