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Cache legacy keys instead of downgrading them

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If someone calls an EVP_PKEY_get0*() function then we create a legacy
key and cache it in the EVP_PKEY - but it doesn't become an "origin" and
it doesn't ever get updated. This will be documented as a restriction of
the EVP_PKEY_get0*() function with provided keys.

Fixes #14020

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/14319)
This commit is contained in:
Matt Caswell 2021-02-24 16:38:28 +00:00
parent ec961f866a
commit b574c6a9ac
7 changed files with 125 additions and 170 deletions
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12
crypto/evp/p_legacy.c
View File

@ -33,15 +33,11 @@ int EVP_PKEY_set1_RSA(EVP_PKEY *pkey, RSA *key)
RSA *EVP_PKEY_get0_RSA(const EVP_PKEY *pkey)
{
if (!evp_pkey_downgrade((EVP_PKEY *)pkey)) {
ERR_raise(ERR_LIB_EVP, EVP_R_INACCESSIBLE_KEY);
return NULL;
}
if (pkey->type != EVP_PKEY_RSA && pkey->type != EVP_PKEY_RSA_PSS) {
ERR_raise(ERR_LIB_EVP, EVP_R_EXPECTING_AN_RSA_KEY);
return NULL;
}
return pkey->pkey.rsa;
return evp_pkey_get_legacy((EVP_PKEY *)pkey);
}
RSA *EVP_PKEY_get1_RSA(EVP_PKEY *pkey)
@ -65,15 +61,11 @@ int EVP_PKEY_set1_EC_KEY(EVP_PKEY *pkey, EC_KEY *key)
EC_KEY *EVP_PKEY_get0_EC_KEY(const EVP_PKEY *pkey)
{
if (!evp_pkey_downgrade((EVP_PKEY *)pkey)) {
ERR_raise(ERR_LIB_EVP, EVP_R_INACCESSIBLE_KEY);
return NULL;
}
if (EVP_PKEY_base_id(pkey) != EVP_PKEY_EC) {
EVPerr(EVP_F_EVP_PKEY_GET0_EC_KEY, EVP_R_EXPECTING_A_EC_KEY);
return NULL;
}
return pkey->pkey.ec;
return evp_pkey_get_legacy((EVP_PKEY *)pkey);
}
EC_KEY *EVP_PKEY_get1_EC_KEY(EVP_PKEY *pkey)

191
crypto/evp/p_lib.c
View File

@ -13,6 +13,7 @@
*/
#include "internal/deprecated.h"
#include <assert.h>
#include <stdio.h>
#include "internal/cryptlib.h"
#include "internal/refcount.h"
@ -740,11 +741,8 @@ void *EVP_PKEY_get0(const EVP_PKEY *pkey)
{
if (pkey == NULL)
return NULL;
if (!evp_pkey_downgrade((EVP_PKEY *)pkey)) {
ERR_raise(ERR_LIB_EVP, EVP_R_INACCESSIBLE_KEY);
return NULL;
}
return pkey->pkey.ptr;
return evp_pkey_get_legacy((EVP_PKEY *)pkey);
}
const unsigned char *EVP_PKEY_get0_hmac(const EVP_PKEY *pkey, size_t *len)
@ -791,15 +789,11 @@ const unsigned char *EVP_PKEY_get0_siphash(const EVP_PKEY *pkey, size_t *len)
# ifndef OPENSSL_NO_DSA
DSA *EVP_PKEY_get0_DSA(const EVP_PKEY *pkey)
{
if (!evp_pkey_downgrade((EVP_PKEY *)pkey)) {
ERR_raise(ERR_LIB_EVP, EVP_R_INACCESSIBLE_KEY);
return NULL;
}
if (pkey->type != EVP_PKEY_DSA) {
ERR_raise(ERR_LIB_EVP, EVP_R_EXPECTING_A_DSA_KEY);
return NULL;
}
return pkey->pkey.dsa;
return evp_pkey_get_legacy((EVP_PKEY *)pkey);
}
int EVP_PKEY_set1_DSA(EVP_PKEY *pkey, DSA *key)
@ -823,15 +817,11 @@ DSA *EVP_PKEY_get1_DSA(EVP_PKEY *pkey)
# ifndef OPENSSL_NO_EC
static ECX_KEY *evp_pkey_get0_ECX_KEY(const EVP_PKEY *pkey, int type)
{
if (!evp_pkey_downgrade((EVP_PKEY *)pkey)) {
ERR_raise(ERR_LIB_EVP, EVP_R_INACCESSIBLE_KEY);
return NULL;
}
if (EVP_PKEY_base_id(pkey) != type) {
ERR_raise(ERR_LIB_EVP, EVP_R_EXPECTING_A_ECX_KEY);
return NULL;
}
return pkey->pkey.ecx;
return evp_pkey_get_legacy((EVP_PKEY *)pkey);
}
static ECX_KEY *evp_pkey_get1_ECX_KEY(EVP_PKEY *pkey, int type)
@ -868,15 +858,11 @@ int EVP_PKEY_set1_DH(EVP_PKEY *pkey, DH *key)
DH *EVP_PKEY_get0_DH(const EVP_PKEY *pkey)
{
if (!evp_pkey_downgrade((EVP_PKEY *)pkey)) {
ERR_raise(ERR_LIB_EVP, EVP_R_INACCESSIBLE_KEY);
return NULL;
}
if (pkey->type != EVP_PKEY_DH && pkey->type != EVP_PKEY_DHX) {
ERR_raise(ERR_LIB_EVP, EVP_R_EXPECTING_A_DH_KEY);
return NULL;
}
return pkey->pkey.dh;
return evp_pkey_get_legacy((EVP_PKEY *)pkey);
}
DH *EVP_PKEY_get1_DH(EVP_PKEY *pkey)
@ -1310,36 +1296,6 @@ size_t EVP_PKEY_get1_encoded_public_key(EVP_PKEY *pkey, unsigned char **ppub)
/*- All methods below can also be used in FIPS_MODULE */
/*
* This reset function must be used very carefully, as it literally throws
* away everything in an EVP_PKEY without freeing them, and may cause leaks
* of memory, what have you.
* The only reason we have this is to have the same code for EVP_PKEY_new()
* and evp_pkey_downgrade().
*/
static int evp_pkey_reset_unlocked(EVP_PKEY *pk)
{
if (pk == NULL)
return 0;
if (pk->lock != NULL) {
const size_t offset = (unsigned char *)&pk->lock - (unsigned char *)pk;
memset(pk, 0, offset);
memset((unsigned char *)pk + offset + sizeof(pk->lock),
0,
sizeof(*pk) - offset - sizeof(pk->lock));
}
/* EVP_PKEY_new uses zalloc so no need to call memset if pk->lock is NULL */
pk->type = EVP_PKEY_NONE;
pk->save_type = EVP_PKEY_NONE;
pk->references = 1;
pk->save_parameters = 1;
return 1;
}
EVP_PKEY *EVP_PKEY_new(void)
{
EVP_PKEY *ret = OPENSSL_zalloc(sizeof(*ret));
@ -1349,8 +1305,10 @@ EVP_PKEY *EVP_PKEY_new(void)
return NULL;
}
if (!evp_pkey_reset_unlocked(ret))
goto err;
ret->type = EVP_PKEY_NONE;
ret->save_type = EVP_PKEY_NONE;
ret->references = 1;
ret->save_parameters = 1;
ret->lock = CRYPTO_THREAD_lock_new();
if (ret->lock == NULL) {
@ -1559,12 +1517,32 @@ int EVP_PKEY_up_ref(EVP_PKEY *pkey)
#ifndef FIPS_MODULE
void evp_pkey_free_legacy(EVP_PKEY *x)
{
if (x->ameth != NULL) {
if (x->ameth->pkey_free != NULL)
x->ameth->pkey_free(x);
const EVP_PKEY_ASN1_METHOD *ameth = x->ameth;
ENGINE *tmpe = NULL;
if (ameth == NULL && x->legacy_cache_pkey.ptr != NULL)
ameth = EVP_PKEY_asn1_find(&tmpe, x->type);
if (ameth != NULL) {
if (x->legacy_cache_pkey.ptr != NULL) {
/*
* We should never have both a legacy origin key, and a key in the
* legacy cache.
*/
assert(x->pkey.ptr == NULL);
/*
* For the purposes of freeing we make the legacy cache look like
* a legacy origin key.
*/
x->pkey = x->legacy_cache_pkey;
x->legacy_cache_pkey.ptr = NULL;
}
if (ameth->pkey_free != NULL)
ameth->pkey_free(x);
x->pkey.ptr = NULL;
}
# ifndef OPENSSL_NO_ENGINE
ENGINE_finish(tmpe);
ENGINE_finish(x->engine);
x->engine = NULL;
ENGINE_finish(x->pmeth_engine);
@ -1877,78 +1855,57 @@ int evp_pkey_copy_downgraded(EVP_PKEY **dest, const EVP_PKEY *src)
return 0;
}
int evp_pkey_downgrade(EVP_PKEY *pk)
void *evp_pkey_get_legacy(EVP_PKEY *pk)
{
EVP_PKEY tmp_copy; /* Stack allocated! */
int rv = 0;
EVP_PKEY *tmp_copy = NULL;
void *ret = NULL;
if (!ossl_assert(pk != NULL))
return 0;
return NULL;
/*
* Throughout this whole function, we must ensure that we lock / unlock
* the exact same lock. Note that we do pass it around a bit.
* If this isn't an assigned provider side key, we just use any existing
* origin legacy key.
*/
if (!CRYPTO_THREAD_write_lock(pk->lock))
return 0;
if (!evp_pkey_is_assigned(pk))
return NULL;
if (!evp_pkey_is_provided(pk))
return pk->pkey.ptr;
/* If this isn't an assigned provider side key, we're done */
if (!evp_pkey_is_assigned(pk) || !evp_pkey_is_provided(pk)) {
rv = 1;
goto end;
}
if (!CRYPTO_THREAD_read_lock(pk->lock))
return NULL;
/*
* To be able to downgrade, we steal the contents of |pk|, then reset
* it, and finally try to make it a downgraded copy. If any of that
* fails, we restore the copied contents into |pk|.
*/
tmp_copy = *pk; /* |tmp_copy| now owns THE lock */
ret = pk->legacy_cache_pkey.ptr;
if (evp_pkey_reset_unlocked(pk)
&& evp_pkey_copy_downgraded(&pk, &tmp_copy)) {
/* Restore the common attributes, then empty |tmp_copy| */
pk->references = tmp_copy.references;
pk->attributes = tmp_copy.attributes;
pk->save_parameters = tmp_copy.save_parameters;
pk->ex_data = tmp_copy.ex_data;
/* Ensure that stuff we've copied won't be freed */
tmp_copy.lock = NULL;
tmp_copy.attributes = NULL;
memset(&tmp_copy.ex_data, 0, sizeof(tmp_copy.ex_data));
/*
* Save the provider side data in the operation cache, so they'll
* find it again. |pk| is new, so it's safe to assume slot zero
* is free.
* Note that evp_keymgmt_util_cache_keydata() increments keymgmt's
* reference count, so we need to decrement it, or there will be a
* leak.
*/
evp_keymgmt_util_cache_keydata(pk, tmp_copy.keymgmt,
tmp_copy.keydata);
EVP_KEYMGMT_free(tmp_copy.keymgmt);
/*
* Clear keymgmt and keydata from |tmp_copy|, or they'll get
* inadvertently freed.
*/
tmp_copy.keymgmt = NULL;
tmp_copy.keydata = NULL;
evp_pkey_free_it(&tmp_copy);
rv = 1;
} else {
/* Restore the original key */
*pk = tmp_copy;
}
end:
if (!CRYPTO_THREAD_unlock(pk->lock))
return 0;
return rv;
return NULL;
if (ret != NULL)
return ret;
if (!evp_pkey_copy_downgraded(&tmp_copy, pk))
return NULL;
if (!CRYPTO_THREAD_write_lock(pk->lock))
goto err;
/* Check again in case some other thread has updated it in the meantime */
ret = pk->legacy_cache_pkey.ptr;
if (ret == NULL) {
/* Steal the legacy key reference from the temporary copy */
ret = pk->legacy_cache_pkey.ptr = tmp_copy->pkey.ptr;
tmp_copy->pkey.ptr = NULL;
}
if (!CRYPTO_THREAD_unlock(pk->lock)) {
ret = NULL;
goto err;
}
err:
EVP_PKEY_free(tmp_copy);
return ret;
}
#endif /* FIPS_MODULE */

13
crypto/evp/pmeth_gn.c
View File

@ -197,7 +197,7 @@ int EVP_PKEY_gen(EVP_PKEY_CTX *ctx, EVP_PKEY **ppkey)
#endif
/*
* Because we still have legacy keys, and evp_pkey_downgrade()
* Because we still have legacy keys
* TODO remove this #legacy internal keys are gone
*/
(*ppkey)->type = ctx->legacy_keytype;
@ -208,8 +208,17 @@ int EVP_PKEY_gen(EVP_PKEY_CTX *ctx, EVP_PKEY **ppkey)
#ifdef FIPS_MODULE
goto not_supported;
#else
if (ctx->pkey && !evp_pkey_downgrade(ctx->pkey))
/*
* If we get here then we're using legacy paramgen/keygen. In that case
* the pkey in ctx (if there is one) had better not be provided (because the
* legacy methods may not know how to handle it). However we can only get
* here if ctx->op.keymgmt.genctx == NULL, but that should never be the case
* if ctx->pkey is provided because we don't allow this when we initialise
* the ctx.
*/
if (ctx->pkey != NULL && !ossl_assert(!evp_pkey_is_provided(ctx->pkey)))
goto not_accessible;
switch (ctx->operation) {
case EVP_PKEY_OP_PARAMGEN:
ret = ctx->pmeth->paramgen(ctx, *ppkey);

3
crypto/evp/pmeth_lib.c
View File

@ -266,8 +266,7 @@ static EVP_PKEY_CTX *int_ctx_new(OSSL_LIB_CTX *libctx,
/*
* Chase down the legacy NID, as that might be needed for diverse
* purposes, such as ensure that EVP_PKEY_type() can return sensible
* values, or that there's a better chance to "downgrade" a key when
* needed. We go through all keymgmt names, because the keytype
* values. We go through all keymgmt names, because the keytype
* that's passed to this function doesn't necessarily translate
* directly.
* TODO: Remove this when #legacy keys are gone.

7
doc/internal/man3/evp_pkey_export_to_provider.pod
View File

@ -53,10 +53,9 @@ evp_pkey_downgrade() returns 1 on success or 0 on error.
=head1 NOTES
Some functions calling evp_pkey_export_to_provider() or evp_pkey_downgrade()
may have received a const key, and may therefore have to cast the key to
non-const form to call this function. Since B<EVP_PKEY> is always dynamically
allocated, this is OK.
Some functions calling evp_pkey_export_to_provider() may have received a const
key, and may therefore have to cast the key to non-const form to call this
function. Since B<EVP_PKEY> is always dynamically allocated, this is OK.
=head1 SEE ALSO

31
doc/internal/man7/EVP_PKEY.pod
View File

@ -178,27 +178,20 @@ OSSL_FUNC_keymgmt_import() function.
=back
=head2 Upgrading and downgrading a key
=head2 Changing a key origin
An B<EVP_PKEY> with a legacy origin will I<never> be upgraded to
become an B<EVP_PKEY> with a provider native origin. Instead, we have
the operation cache as described above, that takes care of the needs
of the diverse operation the application may want to perform.
It is never possible to change the origin of a key. An B<EVP_PKEY> with a legacy
origin will I<never> be upgraded to become an B<EVP_PKEY> with a provider
native origin. Instead, we have the operation cache as described above, that
takes care of the needs of the diverse operation the application may want to
perform.
An B<EVP_PKEY> with a provider native origin, I<may> be downgraded to
be I<transformed> into an B<EVP_PKEY> with a legacy origin. Because
an B<EVP_PKEY> can't have two origins, it means that it stops having a
provider native origin. The previous provider native key data is
moved to the operation cache. Downgrading is performed with the
internal function L<evp_pkey_downgrade(3)>.
I<Downgrading a key is understandably fragile>, and possibly surprising,
and should therefore be done I<as little as possible>, but is needed
to be able to support functions like L<EVP_PKEY_get0_RSA(3)>.
The general recommendation is to use L<evp_pkey_copy_downgraded(3)>
whenever possible, which it should be if the need for a legacy origin
is only internal, or better yet, to remove the need for downgrade at
all.
Similarly an B<EVP_PKEY> with a provider native origin, will I<never> be
downgraded to be I<transformed> into an B<EVP_PKEY> with a legacy origin.
Instead we may have a cached copy of the provider key in legacy form. Once the
cached copy is created it is never updated. Changes made to the provider key
are not reflected back in the cached legacy copy. Similarly changes made to the
cached legacy copy are not reflected back in the provider key.
=head1 SEE ALSO

38
include/crypto/evp.h
View File

@ -608,6 +608,21 @@ DEFINE_STACK_OF(OP_CACHE_ELEM)
#define evp_pkey_is_provided(pk) \
((pk)->keymgmt != NULL)
union legacy_pkey_st {
void *ptr;
struct rsa_st *rsa; /* RSA */
# ifndef OPENSSL_NO_DSA
struct dsa_st *dsa; /* DSA */
# endif
# ifndef OPENSSL_NO_DH
struct dh_st *dh; /* DH */
# endif
# ifndef OPENSSL_NO_EC
struct ec_key_st *ec; /* ECC */
ECX_KEY *ecx; /* X25519, X448, Ed25519, Ed448 */
# endif
};
struct evp_pkey_st {
/* == Legacy attributes == */
int type;
@ -621,24 +636,15 @@ struct evp_pkey_st {
const EVP_PKEY_ASN1_METHOD *ameth;
ENGINE *engine;
ENGINE *pmeth_engine; /* If not NULL public key ENGINE to use */
union {
void *ptr;
struct rsa_st *rsa; /* RSA */
# ifndef OPENSSL_NO_DSA
struct dsa_st *dsa; /* DSA */
# endif
# ifndef OPENSSL_NO_DH
struct dh_st *dh; /* DH */
# endif
# ifndef OPENSSL_NO_EC
struct ec_key_st *ec; /* ECC */
ECX_KEY *ecx; /* X25519, X448, Ed25519, Ed448 */
# endif
} pkey;
/* Union to store the reference to an origin legacy key */
union legacy_pkey_st pkey;
/* Union to store the reference to a non-origin legacy key */
union legacy_pkey_st legacy_cache_pkey;
# endif
/* == Common attributes == */
/* If these are modified, so must evp_pkey_downgrade() */
CRYPTO_REF_COUNT references;
CRYPTO_RWLOCK *lock;
STACK_OF(X509_ATTRIBUTE) *attributes; /* [ 0 ] */
@ -719,7 +725,7 @@ void *evp_pkey_export_to_provider(EVP_PKEY *pk, OSSL_LIB_CTX *libctx,
const char *propquery);
#ifndef FIPS_MODULE
int evp_pkey_copy_downgraded(EVP_PKEY **dest, const EVP_PKEY *src);
int evp_pkey_downgrade(EVP_PKEY *pk);
void *evp_pkey_get_legacy(EVP_PKEY *pk);
void evp_pkey_free_legacy(EVP_PKEY *x);
#endif