Revert "Disable implicit rejection for RSA PKCS#1 (dotnet#95218)"

This reverts commit e3500b8.

To quote Clemens Lang:

> [Disabling implcit rejection] re-enables a Bleichenbacher timing oracle
> attack against PKCS#1v1.5 decryption. See
> https://people.redhat.com/~hkario/marvin/ for details and
> dotnet#95157 (comment) for a
> comment by the researcher who published the vulnerability and proposed the
> change in OpenSSL.

For more details, see:
dotnet#95216 (comment)

Author: omajid

src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/RSA/EncryptDecrypt.cs

@@ -338,10 +338,19 @@ private void RsaCryptRoundtrip(RSAEncryptionPadding paddingMode, bool expectSucc
             Assert.Equal(TestData.HelloBytes, output);
         }
 
-        [ConditionalFact(nameof(PlatformSupportsEmptyRSAEncryption))]
+        [ConditionalFact]
         [SkipOnTargetFramework(TargetFrameworkMonikers.NetFramework)]
         public void RoundtripEmptyArray()
         {
+            if (OperatingSystem.IsIOS() && !OperatingSystem.IsIOSVersionAtLeast(13, 6))
+            {
+                throw new SkipTestException("iOS prior to 13.6 does not reliably support RSA encryption of empty data.");
+            }
+            if (OperatingSystem.IsTvOS() && !OperatingSystem.IsTvOSVersionAtLeast(14, 0))
+            {
+                throw new SkipTestException("tvOS prior to 14.0 does not reliably support RSA encryption of empty data.");
+            }
+
             using (RSA rsa = RSAFactory.Create(TestData.RSA2048Params))
             {
                 void RoundtripEmpty(RSAEncryptionPadding paddingMode)
@@ -692,26 +701,6 @@ public void NotSupportedValueMethods()
             }
         }
 
-        [ConditionalTheory]
-        [InlineData(new byte[] { 1, 2, 3, 4 })]
-        [InlineData(new byte[0])]
-        public void Decrypt_Pkcs1_ErrorsForInvalidPadding(byte[] data)
-        {
-            if (data.Length == 0 && !PlatformSupportsEmptyRSAEncryption)
-            {
-                throw new SkipTestException("Platform does not support RSA encryption of empty data.");
-            }
-
-            using (RSA rsa = RSAFactory.Create(TestData.RSA2048Params))
-            {
-                byte[] encrypted = Encrypt(rsa, data, RSAEncryptionPadding.Pkcs1);
-                encrypted[1] ^= 0xFF;
-
-                // PKCS#1, the data, and the key are all deterministic so this should always throw an exception.
-                Assert.ThrowsAny<CryptographicException>(() => Decrypt(rsa, encrypted, RSAEncryptionPadding.Pkcs1));
-            }
-        }
-
         public static IEnumerable<object[]> OaepPaddingModes
         {
             get
@@ -726,23 +715,5 @@ public static IEnumerable<object[]> OaepPaddingModes
                 }
             }
         }
-
-        public static bool PlatformSupportsEmptyRSAEncryption
-        {
-            get
-            {
-                if (OperatingSystem.IsIOS() && !OperatingSystem.IsIOSVersionAtLeast(13, 6))
-                {
-                    return false;
-                }
-
-                if (OperatingSystem.IsTvOS() && !OperatingSystem.IsTvOSVersionAtLeast(14, 0))
-                {
-                    return false;
-                }
-
-                return true;
-            }
-        }
     }
 }

src/libraries/Native/Unix/System.Security.Cryptography.Native/opensslshim.h

@@ -272,10 +272,8 @@ const EVP_CIPHER* EVP_chacha20_poly1305(void);
     REQUIRED_FUNCTION(ERR_peek_error) \
     REQUIRED_FUNCTION(ERR_peek_error_line) \
     REQUIRED_FUNCTION(ERR_peek_last_error) \
-    REQUIRED_FUNCTION(ERR_pop_to_mark) \
     FALLBACK_FUNCTION(ERR_put_error) \
     REQUIRED_FUNCTION(ERR_reason_error_string) \
-    REQUIRED_FUNCTION(ERR_set_mark) \
     LIGHTUP_FUNCTION(ERR_set_debug) \
     LIGHTUP_FUNCTION(ERR_set_error) \
     REQUIRED_FUNCTION(EVP_aes_128_cbc) \
@@ -330,7 +328,6 @@ const EVP_CIPHER* EVP_chacha20_poly1305(void);
     REQUIRED_FUNCTION(EVP_PKCS82PKEY) \
     REQUIRED_FUNCTION(EVP_PKEY2PKCS8) \
     REQUIRED_FUNCTION(EVP_PKEY_CTX_ctrl) \
-    REQUIRED_FUNCTION(EVP_PKEY_CTX_ctrl_str) \
     REQUIRED_FUNCTION(EVP_PKEY_CTX_free) \
     REQUIRED_FUNCTION(EVP_PKEY_CTX_get0_pkey) \
     REQUIRED_FUNCTION(EVP_PKEY_CTX_new) \
@@ -728,10 +725,8 @@ FOR_ALL_OPENSSL_FUNCTIONS
 #define ERR_peek_error_line ERR_peek_error_line_ptr
 #define ERR_peek_last_error ERR_peek_last_error_ptr
 #define ERR_put_error ERR_put_error_ptr
-#define ERR_pop_to_mark ERR_pop_to_mark_ptr
 #define ERR_reason_error_string ERR_reason_error_string_ptr
 #define ERR_set_debug ERR_set_debug_ptr
-#define ERR_set_mark ERR_set_mark_ptr
 #define ERR_set_error ERR_set_error_ptr
 #define EVP_aes_128_cbc EVP_aes_128_cbc_ptr
 #define EVP_aes_128_cfb8 EVP_aes_128_cfb8_ptr
@@ -785,7 +780,6 @@ FOR_ALL_OPENSSL_FUNCTIONS
 #define EVP_PKCS82PKEY EVP_PKCS82PKEY_ptr
 #define EVP_PKEY2PKCS8 EVP_PKEY2PKCS8_ptr
 #define EVP_PKEY_CTX_ctrl EVP_PKEY_CTX_ctrl_ptr
-#define EVP_PKEY_CTX_ctrl_str EVP_PKEY_CTX_ctrl_str_ptr
 #define EVP_PKEY_CTX_free EVP_PKEY_CTX_free_ptr
 #define EVP_PKEY_CTX_get0_pkey EVP_PKEY_CTX_get0_pkey_ptr
 #define EVP_PKEY_CTX_new EVP_PKEY_CTX_new_ptr

src/libraries/Native/Unix/System.Security.Cryptography.Native/pal_evp_pkey_rsa.c

@@ -63,19 +63,6 @@ static bool ConfigureEncryption(EVP_PKEY_CTX* ctx, RsaPaddingMode padding, const
         {
             return false;
         }
-
-        // OpenSSL 3.2 introduced a change where PKCS#1 RSA decryption does not fail for invalid padding.
-        // If the padding is invalid, the decryption operation returns random data.
-        // See https://github.com/openssl/openssl/pull/13817 for background.
-        // Some Linux distributions backported this change to previous versions of OpenSSL.
-        // Here we do a best-effort to set a flag to revert the behavior to failing if the padding is invalid.
-        ERR_set_mark();
-
-        EVP_PKEY_CTX_ctrl_str(ctx, "rsa_pkcs1_implicit_rejection", "0");
-
-        // Undo any changes to the error queue that may have occured while configuring implicit rejection if the
-        // current version does not support implicit rejection.
-        ERR_pop_to_mark();
     }
     else
     {