We currently implement build-time assertions via a mechanism that
generates a call to an undefined external function that will cause the
link to fail unless the compiler can prove that the asserted condition
is true (and thereby eliminate the undefined function call).
This assertion mechanism can be used for conditions that are not
amenable to the use of static_assert(), since static_assert() will not
allow for proofs via dead code elimination.
Add __attribute__((error(...))) to the undefined external function, so
that the error is raised at compile time rather than at link time.
This allows us to provide a more meaningful error message (which will
include the file name and line number, as with any other compile-time
error), and avoids the need for the caller to specify a unique symbol
name for the external function.
Change the name from linker_assert() to build_assert(), since the
assertion now takes place at compile time rather than at link time.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
There are many ways in which the object for a cryptographic algorithm
may be included, even if not explicitly enabled in config/crypto.h.
For example: the MD5 algorithm is required by TLSv1.1 or earlier, by
iSCSI CHAP authentication, by HTTP digest authentication, and by NTLM
authentication.
In the current implementation, inclusion of an algorithm for any
reason will result in the algorithm's ASN.1 object identifier being
included in the "asn1_algorithms" table, which consequently allows the
algorithm to be used for any ASN1-identified purpose. For example: if
the MD5 algorithm is included in order to support HTTP digest
authentication, then iPXE would accept a (validly signed) TLS
certificate using an MD5 digest.
Split the ASN.1 object identifiers into separate files that are
required only if explicitly enabled in config/crypto.h. This allows
an algorithm to be omitted from the "asn1_algorithms" table even if
the algorithm implementation is dragged in for some other purpose.
The end result is that only the algorithms that are explicitly enabled
in config/crypto.h can be used for ASN1-identified purposes such as
signature verification.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Replace MD5 implementation with one which is around 20% smaller. This
implementation has been verified using the existing MD5 self-tests.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Access to the gpxe.org and etherboot.org domains and associated
resources has been revoked by the registrant of the domain. Work
around this problem by renaming project from gPXE to iPXE, and
updating URLs to match.
Also update README, LOG and COPYRIGHTS to remove obsolete information.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The various types of cryptographic algorithm are fundamentally
different, and it was probably a mistake to try to handle them via a
single common type.
pubkey_algorithm is a placeholder type for now.
Michael Brown