crypto: rsa-pkcs1pad - only allow with rsa

crypto: rsa-pkcs1pad - only allow with rsa

BugLink: https://bugs.launchpad.net/bugs/1969110
commit 9b30430ea356f237945e52f8a3a42158877bd5a9 upstream.

The pkcs1pad template can be instantiated with an arbitrary akcipher
algorithm, which doesn't make sense; it is specifically an RSA padding
scheme.  Make it check that the underlying algorithm really is RSA.

Fixes: 3d5b1ecdea6f ("crypto: rsa - RSA padding algorithm")
Cc: <stable@vger.kernel.org> # v4.5+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 9c8d8f87c213cda58b226ec27b41d5d33c22b181)
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>