UEFI's built-in HTTPS boot mechanism requires the trusted CA
certificates to be provided via the TlsCaCertificates variable.
(There is no equivalent of the iPXE cross-signing mechanism, so it is
not possible for UEFI to automatically use public CA certificates.)
Users who have configured UEFI HTTPS boot to use a custom root of
trust (e.g. a private CA certificate) may find it useful to have iPXE
automatically pick up and use this same root of trust, so that iPXE
can seamlessly fetch files via HTTPS from the same servers that were
trusted by UEFI HTTPS boot, in addition to servers that iPXE can
validate through other means such as cross-signed certificates.
Parse the TlsCaCertificates variable at startup, add any certificates
to the certificate store, and mark these certificates as trusted.
There are no access restrictions on modifying the TlsCaCertificates
variable: anybody with access to write UEFI variables is permitted to
change the root of trust. The UEFI security model assumes that anyone
with access to run code prior to ExitBootServices() or with access to
modify UEFI variables from within a loaded operating system is
supposed to be able to change the system's root of trust for TLS.
Any certificates parsed from TlsCaCertificates will show up in the
output of "certstat", and may be discarded using "certfree" if
unwanted.
Support for parsing TlsCaCertificates is enabled by default in EFI
builds, but may be disabled in config/general.h if needed.
As with the ${trust} setting, the contents of the TlsCaCertificates
variable will be ignored if iPXE has been compiled with an explicit
root of trust by specifying TRUST=... on the build command line.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Instances of cipher and digest algorithms tend to get called
repeatedly to process substantial amounts of data. This is not true
for public-key algorithms, which tend to get called only once or twice
for a given key.
Simplify the public-key algorithm API so that there is no reusable
algorithm context. In particular, this allows callers to omit the
error handling currently required to handle memory allocation (or key
parsing) errors from pubkey_init(), and to omit the cleanup calls to
pubkey_final().
This change does remove the ability for a caller to distinguish
between a verification failure due to a memory allocation failure and
a verification failure due to a bad signature. This difference is not
material in practice: in both cases, for whatever reason, the caller
was unable to verify the signature and so cannot proceed further, and
the cause of the error will be visible to the user via the return
status code.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Asymmetric keys are invariably encountered within ASN.1 structures
such as X.509 certificates, and the various large integers within an
RSA key are themselves encoded using ASN.1.
Simplify all code handling asymmetric keys by passing keys as a single
ASN.1 cursor, rather than separate data and length pointers.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Allow passing a NULL value for the certificate list to all functions
used for identifying an X.509 certificate from an existing set of
certificates, and rename function parameters to indicate that this
certificate list represents an unordered certificate store (rather
than an ordered certificate chain).
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Centralise all current mechanisms for identifying an X.509 certificate
(by raw content, by subject, by issuer and serial number, and by
matching public key), and remove the certstore-specific and
CMS-specific variants of these functions.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Downloading a cross-signed certificate chain to partially replace
(rather than simply extend) an existing chain will require the ability
to discard all certificates after a specified link in the chain.
Extract the relevant logic from x509_free_chain() and expose it
separately as x509_truncate().
Signed-off-by: Michael Brown <mcb30@ipxe.org>
DNS names are case-insensitive, and RFC 5280 (unlike RFC 3280)
mandates support for case-insensitive name comparison in X.509
certificates.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
We surface this debugging information in cases where a cert actually
lacks an issuer, but also in cases where it *has* an issuer, but we
cannot trust it (e.g. due to issues in establishing a trust chain).
Signed-off-by: Josh McSavaney <me@mcsau.cc>
Modified-by: Michael Brown <mcb30@ipxe.org>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Record the root of trust used at the point that a certificate is
validated, redefine validation as checking a certificate against a
specific root of trust, and pass an explicit root of trust when
creating a TLS connection.
This allows a custom TLS connection to be used with a custom root of
trust, without causing any validated certificates to be treated as
valid for normal purposes.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
There is nothing OID-specific about the ASN1_OID_CURSOR macro. Rename
to allow it to be used for constructing ASN.1 cursors with arbitrary
contents.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Add support for SHA-224, SHA-384, and SHA-512 as digest algorithms in
X.509 certificates, and allow the choice of public-key, cipher, and
digest algorithms to be configured at build time via config/crypto.h.
Originally-implemented-by: Tufan Karadere <tufank@gmail.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The current API for Base16 (and Base64) encoding requires the caller
to always provide sufficient buffer space. This prevents the use of
the generic encoding/decoding functionality in some situations, such
as in formatting the hex setting types.
Implement a generic hex_encode() (based on the existing
format_hex_setting()), implement base16_encode() and base16_decode()
in terms of the more generic hex_encode() and hex_decode(), and update
all callers to provide the additional buffer length parameter.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
At some point in the past few years, binutils became more aggressive
at removing unused symbols. To function as a symbol requirement, a
relocation record must now be in a section marked with @progbits and
must not be in a section which gets discarded during the link (either
via --gc-sections or via /DISCARD/).
Update REQUIRE_SYMBOL() to generate relocation records meeting these
criteria. To minimise the impact upon the final binary size, we use
existing symbols (specified via the REQUIRING_SYMBOL() macro) as the
relocation targets where possible. We use R_386_NONE or R_X86_64_NONE
relocation types to prevent any actual unwanted relocation taking
place. Where no suitable symbol exists for REQUIRING_SYMBOL() (such
as in config.c), the macro PROVIDE_REQUIRING_SYMBOL() can be used to
generate a one-byte-long symbol to act as the relocation target.
If there are versions of binutils for which this approach fails, then
the fallback will probably involve killing off REQUEST_SYMBOL(),
redefining REQUIRE_SYMBOL() to use the current definition of
REQUEST_SYMBOL(), and postprocessing the linked ELF file with
something along the lines of "nm -u | wc -l" to check that there are
no undefined symbols remaining.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Expand the concept of the X.509 cache to provide the functionality of
a certificate store. Certificates in the store will be automatically
used to complete certificate chains where applicable.
The certificate store may be prepopulated at build time using the
CERT=... build command line option. For example:
make bin/ipxe.usb CERT=mycert1.crt,mycert2.crt
Certificates within the certificate store are not implicitly trusted;
the trust list is specified using TRUST=... as before. For example:
make bin/ipxe.usb CERT=root.crt TRUST=root.crt
This can be used to embed the full trusted root certificate within the
iPXE binary, which is potentially useful in an HTTPS-only environment
in which there is no HTTP server from which to automatically download
cross-signed certificates or other certificate chain fragments.
This usage of CERT= extends the existing use of CERT= to specify the
client certificate. The client certificate is now identified
automatically by checking for a match against the private key. For
example:
make bin/ipxe.usb CERT=root.crt,client.crt TRUST=root.crt KEY=client.key
Signed-off-by: Michael Brown <mcb30@ipxe.org>
iPXE currently allocates a copy the certificate's common name as a
string. This string is used by the TLS and CMS code to check
certificate names against an expected name, and also appears in
debugging messages.
Provide a function x509_check_name() to centralise certificate name
checking (in preparation for adding subjectAlternativeName support),
and a function x509_name() to provide a name to be used in debugging
messages, and remove the dynamically allocated string.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
If a certificate chain contains no certificate which can be validated
as a standalone certificate (i.e. contains no trusted root
certificates or previously-validated certificates) then iPXE will
currently return a fixed error EACCES_UNTRUSTED. This masks the
actual errors obtained when attempting to validate each certificate as
a standalone certificate, and so makes troubleshooting difficult for
the end user.
Fix by instead returning the error obtained when attempting to
validate the final certificate in the chain as a standalone
certificate. This error is most likely (though not guaranteed) to
represent the "real" problem.
Reported-by: Sven Dreyer <sven@dreyer-net.de>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Discarding the active ARP cache entry in the middle of a download will
substantially disrupt the TCP stream. Try to minimise any such
disruption by treating ARP cache entries as expensive, and discarding
them only when nothing else is available to discard.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
iPXE has no concept of the local time zone, mainly because there is no
viable way to obtain time zone information in the absence of local
state. This causes potential problems with newly-issued certificates
and certificates that are about to expire.
Avoid such problems by allowing an error margin of around 12 hours on
certificate validity periods, similar to the error margin already
allowed for OCSP response timestamps.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Add support for constructing OCSP queries and parsing OCSP responses.
(There is no support yet for actually issuing an OCSP query via an
HTTP POST.)
Signed-off-by: Michael Brown <mcb30@ipxe.org>
X.509 certificate processing currently produces an overwhelming amount
of debugging information. Move some of this from DBGLVL_LOG to
DBGLVL_EXTRA, to make the output more manageable.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
CMS includes an unordered certificate set, from which certificates
must be extracted in order by matching up issuers with subjects. We
will use the same functionality as part of the automatic download of
cross-signing certificates. Generalise cms_find_subject() to
x509_find_subject(), and create x509_auto_append().
Signed-off-by: Michael Brown <mcb30@ipxe.org>
At present, certificate chain validation is treated as an
instantaneous process that can be carried out using only data that is
already in memory. This model does not allow for validation to
include non-instantaneous steps, such as downloading a cross-signing
certificate, or determining certificate revocation status via OCSP.
Redesign the internal representation of certificate chains to allow
chains to outlive the scope of the original source of certificates
(such as a TLS Certificate record).
Allow for certificates to be cached, so that each certificate needs to
be validated only once.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The certificate may be part of an ASN.1-encoded certificate chain, and
so may not be the only object contained within the ASN.1 cursor.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Michael Brown
Josh McSavaney