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Use hardcoded RSA-PSS params
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To be squashed

Signed-off-by: Jakub Jelen <[email protected]>
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@Jakuje
Jakuje committed Jan 27, 2025
1 parent 73713fd commit 542a6ea
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Showing 4 changed files with 125 additions and 258 deletions.
203 changes: 4 additions & 199 deletions src/encoder.c
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Original file line number Diff line number Diff line change
Expand Up @@ -251,197 +251,6 @@ static int p11prov_rsa_pubkey_to_der(P11PROV_OBJ *key, unsigned char **der,
return RET_OSSL_OK;
}

static X509_ALGOR *p11prov_x509_algor_new_from_nid(int nid, int ptype,
void *pval)
{
X509_ALGOR *alg = NULL;
ASN1_OBJECT *obj = NULL;
int ret;

alg = X509_ALGOR_new();
obj = OBJ_nid2obj(nid);
if (alg == NULL || obj == NULL) {
ASN1_OBJECT_free(obj);
return NULL;
}

ret = X509_ALGOR_set0(alg, obj, ptype, pval);
if (ret != 1) {
X509_ALGOR_free(alg);
ASN1_OBJECT_free(obj);
return NULL;
}
return alg;
}

static X509_ALGOR *p11prov_x509_algor_new_from_mgf1_nid(int mgf1_nid)
{
X509_ALGOR *tmpalg = NULL;
ASN1_STRING *enc = NULL;
X509_ALGOR *out = NULL;

tmpalg = p11prov_x509_algor_new_from_nid(mgf1_nid, V_ASN1_UNDEF, NULL);
if (tmpalg == NULL) {
return NULL;
}
enc = ASN1_item_pack(tmpalg, ASN1_ITEM_rptr(X509_ALGOR), NULL);
X509_ALGOR_free(tmpalg);
if (enc == NULL) {
return NULL;
}
out = p11prov_x509_algor_new_from_nid(NID_mgf1, V_ASN1_SEQUENCE, enc);
if (out == NULL) {
ASN1_STRING_free(enc);
}
return out;
}

RSA_PSS_PARAMS *p11prov_encode_rsa_pss_params(int hash_nid, int mgf1_hash_nid,
int saltlen)
{
RSA_PSS_PARAMS *pss = NULL;
int ret;

pss = RSA_PSS_PARAMS_new();
if (pss == NULL) {
return NULL;
}

pss->hashAlgorithm =
p11prov_x509_algor_new_from_nid(hash_nid, V_ASN1_UNDEF, NULL);
if (pss->hashAlgorithm == NULL) {
goto err;
}

pss->maskHash =
p11prov_x509_algor_new_from_nid(mgf1_hash_nid, V_ASN1_UNDEF, NULL);
if (pss->maskHash == NULL) {
goto err;
}

pss->maskGenAlgorithm = p11prov_x509_algor_new_from_mgf1_nid(mgf1_hash_nid);
if (pss->maskGenAlgorithm == NULL) {
goto err;
}

/* The saltLength has default value so it is optional for restrictions */
if (saltlen >= 0) {
pss->saltLength = ASN1_INTEGER_new();
if (pss->saltLength == NULL) {
goto err;
}

ret = ASN1_INTEGER_set(pss->saltLength, saltlen);
if (ret != 1) {
goto err;
}
}
/* the pss->trailerField has a default value 1 so it is optional and we do
* not need to include it in the generated ASN1 for public key restrictions
*/
return pss;

err:
RSA_PSS_PARAMS_free(pss);
return NULL;
}

/* RSA-PSS mechanism map, sorted by priority */
struct rsa_pss_map {
CK_MECHANISM_TYPE pkcs11_mechanism;
CK_MECHANISM_TYPE hash_type;
} rsa_pss_map[P11PROV_N_RSAPSS_MECHS] = {
{ CKM_RSA_PKCS_PSS, CKM_SHA512 },
{ CKM_SHA512_RSA_PKCS_PSS, CKM_SHA512 },
{ CKM_SHA384_RSA_PKCS_PSS, CKM_SHA384 },
{ CKM_SHA256_RSA_PKCS_PSS, CKM_SHA256 },
{ CKM_SHA224_RSA_PKCS_PSS, CKM_SHA224 },
/* Technically OpenSSL will not encode the SHA3 these days so if we will get
* these on PKCS#11 level, we will just fall back to non-PSS Key encoding:
* https://tools.ietf.org/html/rfc8017#appendix-A.2.1
*/
{ CKM_SHA3_512_RSA_PKCS_PSS, CKM_SHA3_512 },
{ CKM_SHA3_384_RSA_PKCS_PSS, CKM_SHA3_384 },
{ CKM_SHA3_256_RSA_PKCS_PSS, CKM_SHA3_256 },
{ CKM_SHA3_224_RSA_PKCS_PSS, CKM_SHA3_224 },
{ CKM_SHA1_RSA_PKCS_PSS, CKM_SHA_1 },
};

/* The PKCS#11 defines CKA_ALLOWED_MECHANISMS listing all allowed mechanisms on
* given key.
* OTOH X509 define parameters that either allow the key operation with any
* parameters or only with one particular parameter combination
* (including hash, mgf, mgf1 hash, salt length and trailer field).
*
* In case we have only one hash algorithm, such as CKM_SHA256_RSA_PKCS_PSS, we
* can derive hash and default parameters.
*
* If there are more or there is a generic CKM_RSA_PKCS_PSS or all the PSS
* mechanisms, we need to generate unrestricted RSA-PSS mechanism
* (V_ASN1_UNDEF). Note, that this is possible to do only on the key itself and
* not on the signature!
*/
static ASN1_STRING *p11prov_encode_rsa_pss(P11PROV_OBJ *obj)
{
CK_ATTRIBUTE *am = p11prov_obj_get_attr(obj, CKA_ALLOWED_MECHANISMS);
CK_MECHANISM_TYPE *allowed;
int am_nmechs, i, nfound = 0, first = -1;
RSA_PSS_PARAMS *pss = NULL;
int nid, ret;
ASN1_STRING *pstr = NULL;

if (am == NULL || am->ulValueLen == 0) {
/* no limitations or no support for allowed mechs. Should not be
* reached.
* TODO we can try also certificate restrictions */
return NULL;
}
allowed = (CK_MECHANISM_TYPE *)am->pValue;
am_nmechs = am->ulValueLen / sizeof(CK_MECHANISM_TYPE);
for (i = 0; i < P11PROV_N_RSAPSS_MECHS; i++) {
bool found = false;
for (int j = 0; j < am_nmechs; j++) {
if (rsa_pss_map[i].pkcs11_mechanism == allowed[j]) {
found = true;
break;
}
}
if (found) {
nfound++;
if (first == -1) {
first = i;
}
}
}
if (i == P11PROV_N_RSAPSS_MECHS) {
/* no RSA-PSS mechanism -- should not be reached */
return NULL;
}

if (nfound > 1 || rsa_pss_map[first].pkcs11_mechanism == CKM_RSA_PKCS_PSS) {
/* no restrictions -- we can not better express limitation on multiple
* mechanisms or this generic PSS mechanism */
return NULL;
}

ret = p11prov_digest_get_nid(rsa_pss_map[i].hash_type, &nid);
if (ret != CKR_OK) {
return NULL;
}

pss = p11prov_encode_rsa_pss_params(nid, nid, -1);
if (pss == NULL) {
return NULL;
}

if (ASN1_item_pack(pss, ASN1_ITEM_rptr(RSA_PSS_PARAMS), &pstr) == NULL) {
RSA_PSS_PARAMS_free(pss);
return NULL;
}
RSA_PSS_PARAMS_free(pss);
return pstr;
}

static X509_PUBKEY *p11prov_rsa_pubkey_to_x509(P11PROV_OBJ *key)
{
X509_PUBKEY *pubkey;
Expand All @@ -463,14 +272,10 @@ static X509_PUBKEY *p11prov_rsa_pubkey_to_x509(P11PROV_OBJ *key)

if (p11prov_obj_is_rsa_pss(key)) {
nid = NID_rsassaPss;
pval = p11prov_encode_rsa_pss(key);
if (pval != NULL) {
/* This is RSA-PSS key with restrictions */
ptype = V_ASN1_SEQUENCE;
} else {
/* This is RSA-PSS key without additional restrictions */
ptype = V_ASN1_UNDEF;
}
/* This is RSA-PSS key without additional restrictions */
pval = NULL;
ptype = V_ASN1_UNDEF;
/* TODO implement restrictions here based on ALLOWED_MECHANISMS */
} else {
/* this is generic RSA key without restrictions */
nid = NID_rsaEncryption;
Expand Down
2 changes: 0 additions & 2 deletions src/encoder.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -42,6 +42,4 @@ extern const OSSL_DISPATCH
p11prov_ec_edwards_encoder_priv_key_info_pem_functions[];
extern const OSSL_DISPATCH p11prov_ec_edwards_encoder_text_functions[];

RSA_PSS_PARAMS *p11prov_encode_rsa_pss_params(int hash_nid, int mgf1_hash_nid,
int saltlen);
#endif /* _ENCODER_H */
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