linux.git/crypto/testmgr.h, branch v6.14

crypto: keywrap - remove unused keywrap algorithm

2025-01-04T00:53:47+00:00

The keywrap (kw) algorithm has no in-tree user.  It has never had an
in-tree user, and the patch that added it provided no justification for
its inclusion.  Even use of it via AF_ALG is impossible, as it uses a
weird calling convention where part of the ciphertext is returned via
the IV buffer, which is not returned to userspace in AF_ALG.

It's also unclear whether any new code in the kernel that does key
wrapping would actually use this algorithm.  It is controversial in the
cryptographic community due to having no clearly stated security goal,
no security proof, poor performance, and only a 64-bit auth tag.  Later
work (https://eprint.iacr.org/2006/221) suggested that the goal is
deterministic authenticated encryption.  But there are now more modern
algorithms for this, and this is not the same as key wrapping, for which
a regular AEAD such as AES-GCM usually can be (and is) used instead.

Therefore, remove this unused code.

There were several special cases for this algorithm in the self-tests,
due to its weird calling convention.  Remove those too.

Cc: Stephan Mueller 
Signed-off-by: Eric Biggers 
Acked-by: Ard Biesheuvel 
Acked-by: Geert Uytterhoeven  # m68k
Signed-off-by: Herbert Xu

crypto: vmac - remove unused VMAC algorithm

2025-01-04T00:52:03+00:00

Remove the vmac64 template, as it has no known users.  It also continues
to have longstanding bugs such as alignment violations (see
https://lore.kernel.org/r/20241226134847.6690-1-evepolonium@gmail.com/).

This code was added in 2009 by commit f1939f7c5645 ("crypto: vmac - New
hash algorithm for intel_txt support").  Based on the mention of
intel_txt support in the commit title, it seems it was added as a
prerequisite for the contemporaneous patch
"intel_txt: add s3 userspace memory integrity verification"
(https://lore.kernel.org/r/4ABF2B50.6070106@intel.com/).  In the design
proposed by that patch, when an Intel Trusted Execution Technology (TXT)
enabled system resumed from suspend, the "tboot" trusted executable
launched the Linux kernel without verifying userspace memory, and then
the Linux kernel used VMAC to verify userspace memory.

However, that patch was never merged, as reviewers had objected to the
design.  It was later reworked into commit 4bd96a7a8185 ("x86, tboot:
Add support for S3 memory integrity protection") which made tboot verify
the memory instead.  Thus the VMAC support in Linux was never used.

No in-tree user has appeared since then, other than potentially the
usual components that allow specifying arbitrary hash algorithms by
name, namely AF_ALG and dm-integrity.  However there are no indications
that VMAC is being used with these components.  Debian Code Search and
web searches for "vmac64" (the actual algorithm name) do not return any
results other than the kernel itself, suggesting that it does not appear
in any other code or documentation.  Explicitly grepping the source code
of the usual suspects (libell, iwd, cryptsetup) finds no matches either.

Before 2018, the vmac code was also completely broken due to using a
hardcoded nonce and the wrong endianness for the MAC.  It was then fixed
by commit ed331adab35b ("crypto: vmac - add nonced version with big
endian digest") and commit 0917b873127c ("crypto: vmac - remove insecure
version with hardcoded nonce").  These were intentionally breaking
changes that changed all the computed MAC values as well as the
algorithm name ("vmac" to "vmac64").  No complaints were ever received
about these breaking changes, strongly suggesting the absence of users.

The reason I had put some effort into fixing this code in 2018 is
because it was used by an out-of-tree driver.  But if it is still needed
in that particular out-of-tree driver, the code can be carried in that
driver instead.  There is no need to carry it upstream.

Cc: Atharva Tiwari 
Cc: Shane Wang 
Signed-off-by: Eric Biggers 
Acked-by: Ard Biesheuvel 
Acked-by: Geert Uytterhoeven  # m68k
Signed-off-by: Herbert Xu

crypto: rsassa-pkcs1 - Reinstate support for legacy protocols

2024-11-10T03:50:54+00:00

Commit 1e562deacecc ("crypto: rsassa-pkcs1 - Migrate to sig_alg backend")
enforced that rsassa-pkcs1 sign/verify operations specify a hash
algorithm.  That is necessary because per RFC 8017 sec 8.2, a hash
algorithm identifier must be prepended to the hash before generating or
verifying the signature ("Full Hash Prefix").

However the commit went too far in that it changed user space behavior:
KEYCTL_PKEY_QUERY system calls now return -EINVAL unless they specify a
hash algorithm.  Intel Wireless Daemon (iwd) is one application issuing
such system calls (for EAP-TLS).

Closer analysis of the Embedded Linux Library (ell) used by iwd reveals
that the problem runs even deeper:  When iwd uses TLS 1.1 or earlier, it
not only queries for keys, but performs sign/verify operations without
specifying a hash algorithm.  These legacy TLS versions concatenate an
MD5 to a SHA-1 hash and omit the Full Hash Prefix:

https://git.kernel.org/pub/scm/libs/ell/ell.git/tree/ell/tls-suites.c#n97

TLS 1.1 was deprecated in 2021 by RFC 8996, but removal of support was
inadvertent in this case.  It probably should be coordinated with iwd
maintainers first.

So reinstate support for such legacy protocols by defaulting to hash
algorithm "none" which uses an empty Full Hash Prefix.

If it is later on decided to remove TLS 1.1 support but still allow
KEYCTL_PKEY_QUERY without a hash algorithm, that can be achieved by
reverting the present commit and replacing it with the following patch:

https://lore.kernel.org/r/ZxalYZwH5UiGX5uj@wunner.de/

It's worth noting that Python's cryptography library gained support for
such legacy use cases very recently, so they do seem to still be a thing.
The Python developers identified IKE version 1 as another protocol
omitting the Full Hash Prefix:

https://github.com/pyca/cryptography/issues/10226
https://github.com/pyca/cryptography/issues/5495

The author of those issues, Zoltan Kelemen, spent considerable effort
searching for test vectors but only found one in a 2019 blog post by
Kevin Jones.  Add it to testmgr.h to verify correctness of this feature.

Examination of wpa_supplicant as well as various IKE daemons (libreswan,
strongswan, isakmpd, raccoon) has determined that none of them seems to
use the kernel's Key Retention Service, so iwd is the only affected user
space application known so far.

Fixes: 1e562deacecc ("crypto: rsassa-pkcs1 - Migrate to sig_alg backend")
Reported-by: Klara Modin 
Tested-by: Klara Modin 
Closes: https://lore.kernel.org/r/2ed09a22-86c0-4cf0-8bda-ef804ccb3413@gmail.com/
Signed-off-by: Lukas Wunner 
Signed-off-by: Herbert Xu

crypto: ecdsa - Support P1363 signature decoding

2024-10-05T05:22:05+00:00

Alternatively to the X9.62 encoding of ecdsa signatures, which uses
ASN.1 and is already supported by the kernel, there's another common
encoding called P1363.  It stores r and s as the concatenation of two
big endian, unsigned integers.  The name originates from IEEE P1363.

Add a P1363 template in support of the forthcoming SPDM library
(Security Protocol and Data Model) for PCI device authentication.

P1363 is prescribed by SPDM 1.2.1 margin no 44:

   "For ECDSA signatures, excluding SM2, in SPDM, the signature shall be
    the concatenation of r and s.  The size of r shall be the size of
    the selected curve.  Likewise, the size of s shall be the size of
    the selected curve.  See BaseAsymAlgo in NEGOTIATE_ALGORITHMS for
    the size of r and s.  The byte order for r and s shall be in big
    endian order.  When placing ECDSA signatures into an SPDM signature
    field, r shall come first followed by s."

Link: https://www.dmtf.org/sites/default/files/standards/documents/DSP0274_1.2.1.pdf
Signed-off-by: Lukas Wunner 
Reviewed-by: Jonathan Cameron 
Reviewed-by: Stefan Berger 
Signed-off-by: Herbert Xu

crypto: ecdsa - Move X9.62 signature decoding into template

2024-10-05T05:22:04+00:00

Unlike the rsa driver, which separates signature decoding and
signature verification into two steps, the ecdsa driver does both in one.

This restricts users to the one signature format currently supported
(X9.62) and prevents addition of others such as P1363, which is needed
by the forthcoming SPDM library (Security Protocol and Data Model) for
PCI device authentication.

Per Herbert's suggestion, change ecdsa to use a "raw" signature encoding
and then implement X9.62 and P1363 as templates which convert their
respective encodings to the raw one.  One may then specify
"x962(ecdsa-nist-XXX)" or "p1363(ecdsa-nist-XXX)" to pick the encoding.

The present commit moves X9.62 decoding to a template.  A separate
commit is going to introduce another template for P1363 decoding.

The ecdsa driver internally represents a signature as two u64 arrays of
size ECC_MAX_BYTES.  This appears to be the most natural choice for the
raw format as it can directly be used for verification without having to
further decode signature data or copy it around.

Repurpose all the existing test vectors for "x962(ecdsa-nist-XXX)" and
create a duplicate of them to test the raw encoding.

Link: https://lore.kernel.org/all/ZoHXyGwRzVvYkcTP@gondor.apana.org.au/
Signed-off-by: Lukas Wunner 
Tested-by: Stefan Berger 
Signed-off-by: Herbert Xu

crypto: akcipher - Drop sign/verify operations

2024-10-05T05:22:04+00:00

A sig_alg backend has just been introduced and all asymmetric
sign/verify algorithms have been migrated to it.

The sign/verify operations can thus be dropped from akcipher_alg.
It is now purely for asymmetric encrypt/decrypt.

Move struct crypto_akcipher_sync_data from internal.h to akcipher.c and
unexport crypto_akcipher_sync_{prep,post}():  They're no longer used by
sig.c but only locally in akcipher.c.

In crypto_akcipher_sync_{prep,post}(), drop various NULL pointer checks
for data->dst as they were only necessary for the verify operation.

In the crypto_sig_*() API calls, remove the forks that were necessary
while algorithms were converted from crypto_akcipher to crypto_sig
one by one.

In struct akcipher_testvec, remove the "params", "param_len" and "algo"
elements as they were only needed for the ecrdsa verify operation.
Remove corresponding dead code from test_akcipher_one() as well.

Signed-off-by: Lukas Wunner 
Signed-off-by: Herbert Xu

crypto: rsassa-pkcs1 - Migrate to sig_alg backend

2024-10-05T05:22:04+00:00

A sig_alg backend has just been introduced with the intent of moving all
asymmetric sign/verify algorithms to it one by one.

Migrate the sign/verify operations from rsa-pkcs1pad.c to a separate
rsassa-pkcs1.c which uses the new backend.

Consequently there are now two templates which build on the "rsa"
akcipher_alg:

* The existing "pkcs1pad" template, which is instantiated as an
  akcipher_instance and retains the encrypt/decrypt operations of
  RSAES-PKCS1-v1_5 (RFC 8017 sec 7.2).

* The new "pkcs1" template, which is instantiated as a sig_instance
  and contains the sign/verify operations of RSASSA-PKCS1-v1_5
  (RFC 8017 sec 8.2).

In a separate step, rsa-pkcs1pad.c could optionally be renamed to
rsaes-pkcs1.c for clarity.  Additional "oaep" and "pss" templates
could be added for RSAES-OAEP and RSASSA-PSS.

Note that it's currently allowed to allocate a "pkcs1pad(rsa)" transform
without specifying a hash algorithm.  That makes sense if the transform
is only used for encrypt/decrypt and continues to be supported.  But for
sign/verify, such transforms previously did not insert the Full Hash
Prefix into the padding.  The resulting message encoding was incompliant
with EMSA-PKCS1-v1_5 (RFC 8017 sec 9.2) and therefore nonsensical.

From here on in, it is no longer allowed to allocate a transform without
specifying a hash algorithm if the transform is used for sign/verify
operations.  This simplifies the code because the insertion of the Full
Hash Prefix is no longer optional, so various "if (digest_info)" clauses
can be removed.

There has been a previous attempt to forbid transform allocation without
specifying a hash algorithm, namely by commit c0d20d22e0ad ("crypto:
rsa-pkcs1pad - Require hash to be present").  It had to be rolled back
with commit b3a8c8a5ebb5 ("crypto: rsa-pkcs1pad: Allow hash to be
optional [ver #2]"), presumably because it broke allocation of a
transform which was solely used for encrypt/decrypt, not sign/verify.
Avoid such breakage by allowing transform allocation for encrypt/decrypt
with and without specifying a hash algorithm (and simply ignoring the
hash algorithm in the former case).

So again, specifying a hash algorithm is now mandatory for sign/verify,
but optional and ignored for encrypt/decrypt.

The new sig_alg API uses kernel buffers instead of sglists, which
avoids the overhead of copying signature and digest from sglists back
into kernel buffers.  rsassa-pkcs1.c is thus simplified quite a bit.

sig_alg is always synchronous, whereas the underlying "rsa" akcipher_alg
may be asynchronous.  So await the result of the akcipher_alg, similar
to crypto_akcipher_sync_{en,de}crypt().

As part of the migration, rename "rsa_digest_info" to "hash_prefix" to
adhere to the spec language in RFC 9580.  Otherwise keep the code
unmodified wherever possible to ease reviewing and bisecting.  Leave
several simplification and hardening opportunities to separate commits.

rsassa-pkcs1.c uses modern __free() syntax for allocation of buffers
which need to be freed by kfree_sensitive(), hence a DEFINE_FREE()
clause for kfree_sensitive() is introduced herein as a byproduct.

Signed-off-by: Lukas Wunner 
Signed-off-by: Herbert Xu

crypto: ecrdsa - Migrate to sig_alg backend

2024-10-05T05:22:04+00:00

A sig_alg backend has just been introduced with the intent of moving all
asymmetric sign/verify algorithms to it one by one.

Migrate ecrdsa.c to the new backend.

One benefit of the new API is the use of kernel buffers instead of
sglists, which avoids the overhead of copying signature and digest
sglists back into kernel buffers.  ecrdsa.c is thus simplified quite
a bit.

Signed-off-by: Lukas Wunner 
Signed-off-by: Herbert Xu

crypto: ecdsa - Migrate to sig_alg backend

2024-10-05T05:22:04+00:00

A sig_alg backend has just been introduced with the intent of moving all
asymmetric sign/verify algorithms to it one by one.

Migrate ecdsa.c to the new backend.

One benefit of the new API is the use of kernel buffers instead of
sglists, which avoids the overhead of copying signature and digest
sglists back into kernel buffers.  ecdsa.c is thus simplified quite
a bit.

Signed-off-by: Lukas Wunner 
Signed-off-by: Herbert Xu

crypto: sig - Introduce sig_alg backend

2024-10-05T05:22:04+00:00

Commit 6cb8815f41a9 ("crypto: sig - Add interface for sign/verify")
began a transition of asymmetric sign/verify operations from
crypto_akcipher to a new crypto_sig frontend.

Internally, the crypto_sig frontend still uses akcipher_alg as backend,
however:

   "The link between sig and akcipher is meant to be temporary.  The
    plan is to create a new low-level API for sig and then migrate
    the signature code over to that from akcipher."
    https://lore.kernel.org/r/ZrG6w9wsb-iiLZIF@gondor.apana.org.au/

   "having a separate alg for sig is definitely where we want to
    be since there is very little that the two types actually share."
    https://lore.kernel.org/r/ZrHlpz4qnre0zWJO@gondor.apana.org.au/

Take the next step of that migration and augment the crypto_sig frontend
with a sig_alg backend to which all algorithms can be moved.

During the migration, there will briefly be signature algorithms that
are still based on crypto_akcipher, whilst others are already based on
crypto_sig.  Allow for that by building a fork into crypto_sig_*() API
calls (i.e. crypto_sig_maxsize() and friends) such that one of the two
backends is selected based on the transform's cra_type.

Signed-off-by: Lukas Wunner 
Signed-off-by: Herbert Xu