bigint_mod_multiply() and bigint_mod_exp() require a fixed amount of
temporary storage for intermediate results. (The amount of temporary
storage required depends upon the size of the integers involved.)
When performing calculations for 4096-bit RSA the amount of temporary
storage space required will exceed 2.5kB, which is too much to
allocate on the stack. Avoid this problem by forcing the caller to
allocate temporary storage.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
RSA requires modular exponentiation using arbitrarily large integers.
Given the sizes of the modulus and exponent, all required calculations
can be done without any further dynamic storage allocation. The x86
architecture allows for efficient large integer support via inline
assembly using the instructions that take advantage of the carry flag
(e.g. "adcl", "rcrl").
This implemention is approximately 80% smaller than the (more generic)
AXTLS implementation.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
All axTLS files are now vanilla versions of the upstream axTLS files,
with one minor exception: the unused "ctx" parameter of
bi_int_divide() has been marked with "__unused" to avoid a compilation
error.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Both HMAC_DRBG using SHA-1 and HMAC_DRBG using SHA-256 are Approved
algorithms in ANS X9.82 for our chosen security strength of 128 bits.
However, general recommendations (see e.g. NIST SP800-57) are to use a
larger hash function in preference to SHA-1.
Since SHA-256 is required anyway for TLSv1.2 support, there is no code
size penalty for switching HMAC_DRBG to also use SHA-256.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
ANS X9.82 Part 4 (April 2011 Draft) Section 13.3.4.2 states that "When
using the derivation function based on a hash function, the output
length of the hash function shall meet or exceed the security strength
indicated by the min_entropy parameter in the Get_entropy_input call",
although this criteria is missing from the pseudocode provided in the
same section.
Add a test for this condition, and upgrade from SHA-1 to SHA-256 since
SHA-1 has an output length of 160 bits, which is insufficient for
generating the (128 * 3/2 = 192) bits required when instantiating the
128-bit strength DRBG.
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>
Replace SHA-1 implementation from AXTLS with a dedicated iPXE
implementation which is around 40% smaller. This implementation has
been verified using the existing SHA-1 self-tests (including the NIST
SHA-1 test vectors).
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Advertise support for TLS version 1.1, and be prepared to downgrade to
TLS version 1.0. Tested against Apache with mod_gnutls, using the
GnuTLSPriorities directive to force specific protocol versions.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Allow packet transmission to be deferred pending successful ARP
resolution. This avoids the time spent waiting for a higher-level
protocol (e.g. TCP or TFTP) to attempt retransmission.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Some PXE stacks (observed with a QLogic 8242) will always try to
prepend a link-layer header, even if the caller uses P_UNKNOWN to
indicate that the link-layer header has already been filled in. This
results in an invalid packet being transmitted.
Work around these faulty PXE stacks where possible by stripping the
existing link-layer header and allowing the PXE stack to (re)construct
the link-layer header itself.
Originally-fixed-by: Buck Huppmann <buckh@pobox.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Some iSCSI targets respond to a PDU before receiving the padding
bytes. If the target responds quickly enough, this can cause iPXE to
start processing a new TX PDU before the padding bytes have been sent,
which results in a protocol violation.
Fix by always transmitting the padding bytes along with the data
segment.
Originally-fixed-by: Shyam Iyer <shyam_iyer@dell.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Abstract out the generic line-handling portions of the syslog
putchar() routine, to allow use by other console types.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Separate out the core HTTP functionality (which is shared by both HTTP
and HTTPS) from the provision of the "http://" URI opener. This
allows for builds that support only "https://" URIs.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
RSA requires the generation of random non-zero bytes (i.e. a sequence
of random numbers in the range [0x01,0xff]). ANS X9.82 provides
various Approved methods for converting random bits into random
numbers. The simplest such method is the Simple Discard Method.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
ANS X9.82 specifies several Approved Sources of Entropy Input (SEI).
One such SEI uses an entropy source as the Source of Entropy Input,
condensing each entropy source output after each GetEntropy call.
This can be implemented relatively cheaply in iPXE and avoids the need
to allocate potentially very large buffers.
(Note that the terms "entropy source" and "Source of Entropy Input"
are not synonyms within the context of ANS X9.82.)
Use the iPXE API mechanism to allow entropy sources to be selected at
compilation time.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Treat an empty (zeroed) DRBG as invalid. This ensures that a DRBG
that has not yet been instantiated (or that has been uninstantiated)
will refuse to attempt to generate random bits.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
ANS X9.82 specifies several Approved derivation functions for use in
distributing entropy throughout a buffer. One such derivation
function is Hash_df, which can be implemented using the existing iPXE
SHA-1 functionality.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
iPXE exposes some extended capabilities via the PXE FILE API to allow
NBPs such as pxelinux to use protocols other than TFTP. Provide an
equivalent interface as a UEFI protocol so that EFI binaries may also
take advantage of iPXE's extended capabilities.
This can be used with a patched version of elilo, for example:
http://comments.gmane.org/gmane.comp.boot-loaders.elilo.general/147
Signed-off-by: Michael Brown <mcb30@ipxe.org>
ANS X9.82 specifies that an Approved DRBG must consist of an Approved
algorithm wrapped inside an envelope which handles entropy gathering,
prediction resistance, automatic reseeding and other housekeeping
tasks.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Cryptographic random number generation requires an entropy source,
which is used as the input to a Deterministic Random Bit Generator
(DRBG).
iPXE does not currently have a suitable entropy source. Provide a
dummy source to allow the DRBG code to be implemented.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
ANS X9.82 specifies several Approved algorithms for use in a
Deterministic Random Bit Generator (DRBG). One such algorithm is
HMAC_DRBG, which can be implemented using the existing iPXE SHA-1 and
HMAC functionality. This algorithm provides a maximum security
strength of 128 bits.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
All users of imgdownload() require registration of the image, so make
registration an integral part of imgdownload() itself and simplify the
"action" parameter to be one of image_select(), image_exec() et al.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
