The elliptic curve point representation for the x25519 curve includes
only the X value, since the curve is designed such that the Montgomery
ladder does not need to ever know or calculate a Y value. There is no
curve point format byte: the public key data is simply the X value.
The pre-master secret is also simply the X value of the shared secret
curve point.
The point representation for the NIST curves includes both X and Y
values, and a single curve point format byte that must indicate that
the format is uncompressed. The pre-master secret for the NIST curves
does not include both X and Y values: only the X value is used.
Extend the definition of an elliptic curve to allow the point size to
be specified separately from the key size, and extend the definition
of a TLS named curve to include an optional curve point format byte
and a pre-master secret length.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Split out the portion of tls_send_client_key_exchange_ecdhe() that
actually performs the elliptic curve key exchange into a separate
function ecdhe_key().
Signed-off-by: Michael Brown <mcb30@ipxe.org>
In debug messages, big integers are currently printed as hex dumps.
This is quite verbose and cumbersome to check against external
sources.
Add bigint_ntoa() to transcribe big integers into a static buffer
(following the model of inet_ntoa(), eth_ntoa(), uuid_ntoa(), etc).
Abbreviate big integers that will not fit within the static buffer,
showing both the most significant and least significant digits in the
transcription. This is generally the most useful form when visually
comparing against external sources (such as test vectors, or results
produced by high-level languages).
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Calculating the Montgomery constant (R^2 mod N) is done in our
implementation by zeroing the double-width representation of N,
subtracting N once to give (R^2 - N) in order to obtain a positive
value, then reducing this value modulo N.
Extract this logic from bigint_mod_exp() to a separate function
bigint_reduce_supremum(), to allow for reuse by other code.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Classic Montgomery reduction involves a single conditional subtraction
to ensure that the result is strictly less than the modulus.
When performing chains of Montgomery multiplications (potentially
interspersed with additions and subtractions), it can be useful to
work with values that are stored modulo some small multiple of the
modulus, thereby allowing some reductions to be elided. Each addition
and subtraction stage will increase this running multiple, and the
following multiplication stages can be used to reduce the running
multiple since the reduction carried out for multiplication products
is generally strong enough to absorb some additional bits in the
inputs. This approach is already used in the x25519 code, where
multiplication takes two 258-bit inputs and produces a 257-bit output.
Split out the conditional subtraction from bigint_montgomery() and
provide a separate bigint_montgomery_relaxed() for callers who do not
require immediate reduction to within the range of the modulus.
Modular exponentiation could potentially make use of relaxed
Montgomery multiplication, but this would require R>4N, i.e. that the
two most significant bits of the modulus be zero. For both RSA and
DHE, this would necessitate extending the modulus size by one element,
which would negate any speed increase from omitting the conditional
subtractions. We therefore retain the use of classic Montgomery
reduction for modular exponentiation, apart from the final conversion
out of Montgomery form.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Reduce the number of parameters passed to bigint_montgomery() by
calculating the inverse of the modulus modulo the element size on
demand. Cache the result, since Montgomery reduction will be used
repeatedly with the same modulus value.
In all currently supported algorithms, the modulus is a public value
(or a fixed value defined by specification) and so this non-constant
timing does not leak any private information.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
There is no further need for a standalone modular multiplication
primitive, since the only consumer is modular exponentiation (which
now uses Montgomery multiplication instead).
Remove the now obsolete bigint_mod_multiply().
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Speed up modular exponentiation by using Montgomery reduction rather
than direct modular reduction.
Montgomery reduction in base 2^n requires the modulus to be coprime to
2^n, which would limit us to requiring that the modulus is an odd
number. Extend the implementation to include support for
exponentiation with even moduli via Garner's algorithm as described in
"Montgomery reduction with even modulus" (Koç, 1994).
Since almost all use cases for modular exponentation require a large
prime (and hence odd) modulus, the support for even moduli could
potentially be removed in future.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Montgomery reduction is substantially faster than direct reduction,
and is better suited for modular exponentiation operations.
Add bigint_montgomery() to perform the Montgomery reduction operation
(often referred to as "REDC"), along with some test vectors.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Montgomery reduction requires only the least significant element of an
inverse modulo 2^k, which in turn depends upon only the least
significant element of the invertend.
Use the inverse size (rather than the invertend size) as the effective
size for bigint_mod_invert(). This eliminates around 97% of the loop
iterations for a typical 2048-bit RSA modulus.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
With a slight modification to the algorithm to ignore bits of the
residue that can never contribute to the result, it is possible to
reuse the as-yet uncalculated portions of the inverse to hold the
residue. This removes the requirement for additional temporary
working space.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Direct modular reduction is expected to be used in situations where
there is no requirement to retain the original (unreduced) value.
Modify the API for bigint_reduce() to reduce the value in place,
(removing the separate result buffer), impose a constraint that the
modulus and value have the same size, and require the modulus to be
passed in writable memory (to allow for scaling in place). This
removes the requirement for additional temporary working space.
Reverse the order of arguments so that the constant input is first,
to match the usage pattern for bigint_add() et al.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Expose the effective carry (or borrow) out flag from big integer
addition and subtraction, and use this to elide an explicit bit test
when performing x25519 reduction.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Add a dedicated bigint_msb_is_set() to reduce the amount of open
coding required in the common case of testing the sign of a two's
complement big integer.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Running with flat physical addressing is a fairly common early boot
environment. Rename UACCESS_EFI to UACCESS_FLAT so that this code may
be reused in non-UEFI boot environments that also use flat physical
addressing.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Montgomery multiplication requires calculating the inverse of the
modulus modulo a larger power of two.
Add bigint_mod_invert() to calculate the inverse of any (odd) big
integer modulo an arbitrary power of two, using a lightly modified
version of the algorithm presented in "A New Algorithm for Inversion
mod p^k (Koç, 2017)".
The power of two is taken to be 2^k, where k is the number of bits
available in the big integer representation of the invertend. The
inverse modulo any smaller power of two may be obtained simply by
masking off the relevant bits in the inverse.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Allow scripts to read basic information from USB device descriptors
via the settings mechanism. For example:
echo USB vendor ID: ${usb/${busloc}.8.2}
echo USB device ID: ${usb/${busloc}.10.2}
echo USB manufacturer name: ${usb/${busloc}.14.0}
The general syntax is
usb/<bus:dev>.<offset>.<length>
where bus:dev is the USB bus:device address (as obtained via the
"usbscan" command, or from e.g. ${net0/busloc} for a USB network
device), and <offset> and <length> select the required portion of the
USB device descriptor.
Following the usage of SMBIOS settings tags, a <length> of zero may be
used to indicate that the byte at <offset> contains a USB string
descriptor index, and an <offset> of zero may be used to indicate that
the <length> contains a literal USB string descriptor index.
Since the byte at offset zero can never contain a string index, and a
literal string index can never be zero, the combination of both
<length> and <offset> being zero may be used to indicate that the
entire device descriptor is to be read as a raw hex dump.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Implement a "usbscan" command as a direct analogy of the existing
"pciscan" command, allowing scripts to iterate over all detected USB
devices.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Faster modular multiplication algorithms such as Montgomery
multiplication will still require the ability to perform a single
direct modular reduction.
Neaten up the implementation of direct reduction and split it out into
a separate bigint_reduce() function, complete with its own unit tests.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Every architecture uses the same implementation for bigint_is_set(),
and there is no reason to suspect that a future CPU architecture will
provide a more efficient way to implement this operation.
Simplify the code by providing a single architecture-independent
implementation of bigint_is_set().
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The big integer shift operations are misleadingly described as
rotations since the original x86 implementations are essentially
trivial loops around the relevant rotate-through-carry instruction.
The overall operation performed is a shift rather than a rotation.
Update the function names and descriptions to reflect this.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
An n-bit multiplication product may be added to up to two n-bit
integers without exceeding the range of a (2n)-bit integer:
(2^n - 1)*(2^n - 1) + (2^n - 1) + (2^n - 1) = 2^(2n) - 1
Exploit this to perform big integer multiplication in constant time
without requiring the caller to provide temporary carry space.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
All consumers of profile_timestamp() currently treat the value as an
unsigned long. Only the elapsed number of ticks is ever relevant: the
absolute value of the timestamp is not used. Profiling is used to
measure short durations that are generally fewer than a million CPU
cycles, for which an unsigned long is easily large enough.
Standardise the return type of profile_timestamp() as unsigned long
across all CPU architectures. This allows 32-bit architectures such
as i386 and riscv32 to omit all logic associated with retrieving the
upper 32 bits of the 64-bit hardware counter, which simplifies the
code and allows riscv32 and riscv64 to share the same implementation.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Big integer multiplication currently performs immediate carry
propagation from each step of the long multiplication, relying on the
fact that the overall result has a known maximum value to minimise the
number of carries performed without ever needing to explicitly check
against the result buffer size.
This is not a constant-time algorithm, since the number of carries
performed will be a function of the input values. We could make it
constant-time by always continuing to propagate the carry until
reaching the end of the result buffer, but this would introduce a
large number of redundant zero carries.
Require callers of bigint_multiply() to provide a temporary carry
storage buffer, of the same size as the result buffer. This allows
the carry-out from the accumulation of each double-element product to
be accumulated in the temporary carry space, and then added in via a
single call to bigint_add() after the multiplication is complete.
Since the structure of big integer multiplication is identical across
all current CPU architectures, provide a single shared implementation
of bigint_multiply(). The architecture-specific operation then
becomes the multiplication of two big integer elements and the
accumulation of the double-element product.
Note that any intermediate carry arising from accumulating the lower
half of the double-element product may be added to the upper half of
the double-element product without risk of overflow, since the result
of multiplying two n-bit integers can never have all n bits set in its
upper half. This simplifies the carry calculations for architectures
such as RISC-V and LoongArch64 that do not have a carry flag.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Add support for building iPXE as a 64-bit or 32-bit RISC-V binary, for
either UEFI or Linux userspace platforms. For example:
# RISC-V 64-bit UEFI
make CROSS=riscv64-linux-gnu- bin-riscv64-efi/ipxe.efi
# RISC-V 32-bit UEFI
make CROSS=riscv64-linux-gnu- bin-riscv32-efi/ipxe.efi
# RISC-V 64-bit Linux
make CROSS=riscv64-linux-gnu- bin-riscv64-linux/tests.linux
qemu-riscv64 -L /usr/riscv64-linux-gnu/sys-root \
./bin-riscv64-linux/tests.linux
# RISC-V 32-bit Linux
make CROSS=riscv64-linux-gnu- SYSROOT=/usr/riscv32-linux-gnu/sys-root \
bin-riscv32-linux/tests.linux
qemu-riscv32 -L /usr/riscv32-linux-gnu/sys-root \
./bin-riscv32-linux/tests.linux
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Define a cpu_halt() function which is architecture-specific but
platform-independent, and merge the multiple architecture-specific
implementations of the EFI cpu_nap() function into a single central
efi_cpu_nap() that uses cpu_halt() if applicable.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The definitions of the setjmp() and longjmp() functions are common to
all architectures, with only the definition of the jump buffer
structure being architecture-specific.
Move the architecture-specific portions to bits/setjmp.h and provide a
common setjmp.h for the function definitions.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Move the <gdbmach.h> file to <bits/gdbmach.h>, and provide a common
dummy implementation for all architectures that have not yet
implemented support for GDB.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Simplify the process of adding a new CPU architecture by providing
common implementations of typically empty architecture-specific header
files.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
This patch adds support for the AQtion Ethernet controller, enabling
iPXE to recognize and utilize the specific models (AQC114, AQC113, and
AQC107).
Tested-by: Animesh Bhatt <animeshb@marvell.com>
Signed-off-by: Animesh Bhatt <animeshb@marvell.com>
Add the "imgdecrypt" command that can be used to decrypt a detached
encrypted data image using a cipher key obtained from a separate CMS
envelope image. For example:
# Create non-detached encrypted CMS messages
#
openssl cms -encrypt -binary -aes-256-gcm -recip client.crt \
-in vmlinuz -outform DER -out vmlinuz.cms
openssl cms -encrypt -binary -aes-256-gcm -recip client.crt \
-in initrd.img -outform DER -out initrd.img.cms
# Detach data from envelopes (using iPXE's contrib/crypto/cmsdetach)
#
cmsdetach vmlinuz.cms -d vmlinuz.dat -e vmlinuz.env
cmsdetach initrd.img.cms -d initrd.img.dat -e initrd.img.env
and then within iPXE:
#!ipxe
imgfetch http://192.168.0.1/vmlinuz.dat
imgfetch http://192.168.0.1/initrd.img.dat
imgdecrypt vmlinuz.dat http://192.168.0.1/vmlinuz.env
imgdecrypt initrd.img.dat http://192.168.0.1/initrd.img.env
boot vmlinuz
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Add support for decrypting images containing detached encrypted data
using a cipher key obtained from a separate CMS envelope image (in DER
or PEM format).
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Some ASN.1 OID-identified algorithms require additional parameters,
such as an initialisation vector for a block cipher. The structure of
the parameters is defined by the individual algorithm.
Extend asn1_algorithm() to allow these additional parameters to be
returned via a separate ASN.1 cursor.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Reduce the number of dynamic allocations required to parse a CMS
message by retaining the ASN.1 cursor returned from image_asn1() for
the lifetime of the CMS message. This allows embedded ASN.1 cursors
to be used for parsed objects within the message, such as embedded
signatures.
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>
The TLS connection structure has grown to become unmanageably large as
new features and support for new TLS protocol versions have been added
over time.
Split out the portions of struct tls_connection that are specific to
client and server operations into separate structures, and simplify
some structure field names.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The TLS connection structure has grown to become unmanageably large as
new features and support for new TLS protocol versions have been added
over time.
Split out the portions of struct tls_connection that are specific to
transmit and receive operations into separate structures, and simplify
some structure field names.
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>
Generalise the logic for identifying the matching PCI root bridge I/O
protocol to allow for identifying the closest matching PCI bus:dev.fn
address range, and use this to provide PCI address range discovery
(while continuing to inhibit automatic PCI bus probing).
This allows the "pciscan" command to work as expected under UEFI.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The UEFI device model requires us to not probe the PCI bus directly,
but instead to wait to be offered the opportunity to drive devices via
our driver service binding handle.
We currently inhibit PCI bus probing by having pci_discover() return
an empty range when using the EFI PCI I/O API. This has the unwanted
side effect that scanning the bus manually using the "pciscan" command
will also fail to discover any devices.
Separate out the concept of being allowed to probe PCI buses from the
mechanism for discovering PCI bus:dev.fn address ranges, so that this
limitation may be removed.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
There is some exploitable similarity between the data structures used
for representing CMS signatures and CMS encryption keys. In both
cases, the CMS message fundamentally encodes a list of participants
(either message signers or message recipients), where each participant
has an associated certificate and an opaque octet string representing
the signature or encrypted cipher key. The ASN.1 structures are not
identical, but are sufficiently similar to be worth exploiting: for
example, the SignerIdentifier and RecipientIdentifier data structures
are defined identically.
Rename data structures and functions, and add the concept of a CMS
message type.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Extend the definition of an ASN.1 OID-identified algorithm to include
a potential cipher suite, and add identifiers for AES-CBC and AES-GCM.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The cms_signature() and cms_verify() functions currently accept raw
data pointers. This will not be possible for cms_decrypt(), which
will need the ability to extract fragments of ASN.1 data from a
potentially large image.
Change cms_signature() and cms_verify() to accept an image as an input
parameter, and move the responsibility for setting the image trust
flag within cms_verify() since that now becomes a more natural fit.
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>
Michael Brown
Animesh Bhatt