Backport the RSA_get0_pss_params() function from master

This is a missing accessor in order to obtain PSS parameters from an
RSA key, which should also be available in 1.1.1.
Reviewed-by: NRichard Levitte <levitte@openssl.org>
Reviewed-by: NTomas Mraz <tmraz@fedoraproject.org>
(Merged from https://github.com/openssl/openssl/pull/10568)

crypto/rsa/rsa_lib.c

@@ -451,6 +451,11 @@ const BIGNUM *RSA_get0_iqmp(const RSA *r)
     return r->iqmp;
 }
 
+const RSA_PSS_PARAMS *RSA_get0_pss_params(const RSA *r)
+{
+    return r->pss;
+}
+
 void RSA_clear_flags(RSA *r, int flags)
 {
     r->flags &= ~flags;

doc/man3/RSA_get0_key.pod

@@ -5,7 +5,7 @@
 RSA_set0_key, RSA_set0_factors, RSA_set0_crt_params, RSA_get0_key,
 RSA_get0_factors, RSA_get0_crt_params,
 RSA_get0_n, RSA_get0_e, RSA_get0_d, RSA_get0_p, RSA_get0_q,
-RSA_get0_dmp1, RSA_get0_dmq1, RSA_get0_iqmp,
+RSA_get0_dmp1, RSA_get0_dmq1, RSA_get0_iqmp, RSA_get0_pss_params,
 RSA_clear_flags,
 RSA_test_flags, RSA_set_flags, RSA_get0_engine, RSA_get_multi_prime_extra_count,
 RSA_get0_multi_prime_factors, RSA_get0_multi_prime_crt_params,
@@ -33,6 +33,7 @@ RSA_set0_multi_prime_params, RSA_get_version
  const BIGNUM *RSA_get0_dmp1(const RSA *r);
  const BIGNUM *RSA_get0_dmq1(const RSA *r);
  const BIGNUM *RSA_get0_iqmp(const RSA *r);
+ const RSA_PSS_PARAMS *RSA_get0_pss_params(const RSA *r);
  void RSA_clear_flags(RSA *r, int flags);
  int RSA_test_flags(const RSA *r, int flags);
  void RSA_set_flags(RSA *r, int flags);
@@ -98,6 +99,8 @@ retrieved separately by the corresponding function
 RSA_get0_n(), RSA_get0_e(), RSA_get0_d(), RSA_get0_p(), RSA_get0_q(),
 RSA_get0_dmp1(), RSA_get0_dmq1(), and RSA_get0_iqmp(), respectively.
 
+RSA_get0_pss_params() is used to retrieve the RSA-PSS parameters.
+
 RSA_set_flags() sets the flags in the B<flags> parameter on the RSA
 object. Multiple flags can be passed in one go (bitwise ORed together).
 Any flags that are already set are left set. RSA_test_flags() tests to

include/openssl/ossl_typ.h

@@ -109,6 +109,7 @@ typedef struct dsa_method DSA_METHOD;
 
 typedef struct rsa_st RSA;
 typedef struct rsa_meth_st RSA_METHOD;
+typedef struct rsa_pss_params_st RSA_PSS_PARAMS;
 
 typedef struct ec_key_st EC_KEY;
 typedef struct ec_key_method_st EC_KEY_METHOD;

include/openssl/rsa.h

@@ -224,6 +224,7 @@ const BIGNUM *RSA_get0_q(const RSA *d);
 const BIGNUM *RSA_get0_dmp1(const RSA *r);
 const BIGNUM *RSA_get0_dmq1(const RSA *r);
 const BIGNUM *RSA_get0_iqmp(const RSA *r);
+const RSA_PSS_PARAMS *RSA_get0_pss_params(const RSA *r);
 void RSA_clear_flags(RSA *r, int flags);
 int RSA_test_flags(const RSA *r, int flags);
 void RSA_set_flags(RSA *r, int flags);
@@ -279,14 +280,14 @@ int RSA_pkey_ctx_ctrl(EVP_PKEY_CTX *ctx, int optype, int cmd, int p1, void *p2);
 DECLARE_ASN1_ENCODE_FUNCTIONS_const(RSA, RSAPublicKey)
 DECLARE_ASN1_ENCODE_FUNCTIONS_const(RSA, RSAPrivateKey)
 
-typedef struct rsa_pss_params_st {
+struct rsa_pss_params_st {
     X509_ALGOR *hashAlgorithm;
     X509_ALGOR *maskGenAlgorithm;
     ASN1_INTEGER *saltLength;
     ASN1_INTEGER *trailerField;
     /* Decoded hash algorithm from maskGenAlgorithm */
     X509_ALGOR *maskHash;
-} RSA_PSS_PARAMS;
+};
 
 DECLARE_ASN1_FUNCTIONS(RSA_PSS_PARAMS)
 

util/libcrypto.num

@@ -4586,3 +4586,4 @@ EVP_PKEY_meth_set_digestsign            4539	1_1_1e	EXIST::FUNCTION:
 EVP_PKEY_meth_set_digestverify          4540	1_1_1e	EXIST::FUNCTION:
 EVP_PKEY_meth_get_digestverify          4541	1_1_1e	EXIST::FUNCTION:
 EVP_PKEY_meth_get_digestsign            4542	1_1_1e	EXIST::FUNCTION:
+RSA_get0_pss_params                     4543	1_1_1e	EXIST::FUNCTION:RSA