Syscalls must validate that their reserved arguments are zero and return
EINVAL otherwise. Otherwise, it will be impossible to actually use them
for anything in the future because existing programs may be passing
garbage in. This is standard practice when adding new APIs.
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
SP800-56A defines the use of DH with key derivation function based on a
counter. The input to the KDF is defined as (DH shared secret || other
information). The value for the "other information" is to be provided by
the caller.
The KDF is implemented using the hash support from the kernel crypto API.
The implementation uses the symmetric hash support as the input to the
hash operation is usually very small. The caller is allowed to specify
the hash name that he wants to use to derive the key material allowing
the use of all supported hashes provided with the kernel crypto API.
As the KDF implements the proper truncation of the DH shared secret to
the requested size, this patch fills the caller buffer up to its size.
The patch is tested with a new test added to the keyutils user space
code which uses a CAVS test vector testing the compliance with
SP800-56A.
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: David Howells <dhowells@redhat.com>
