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Lukas Wunner 1e562deace crypto: rsassa-pkcs1 - Migrate to sig_alg backend 
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 c0d20d22e0 ("crypto:
rsa-pkcs1pad - Require hash to be present").  It had to be rolled back
with commit b3a8c8a5eb ("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 <lukas@wunner.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2024-10-05 13:22:04 +08:00
..
apparmor lsm/stable-6.12 PR 20240911 2024-09-16 18:19:47 +02:00
bpf bpf: lsm: Set bpf_lsm_blob_sizes.lbs_task to 0 2024-09-11 10:11:36 -07:00
integrity crypto: rsassa-pkcs1 - Migrate to sig_alg backend 2024-10-05 13:22:04 +08:00
ipe ipe: Add missing terminator to list of unit tests 2024-09-23 15:53:37 -04:00
keys KEYS: trusted: dcp: fix leak of blob encryption key 2024-08-15 22:01:14 +03:00
landlock Landlock updates for v6.12-rc1 2024-09-24 10:40:11 -07:00
loadpin introduce fd_file(), convert all accessors to it. 2024-08-12 22:00:43 -04:00
lockdown lockdown: Make lockdown_lsmid static 2024-08-15 12:11:42 -04:00
safesetid lsm: mark the lsm_id variables are marked as static 2023-11-12 22:54:42 -05:00
selinux bpf-next-6.12-struct-fd 2024-09-24 14:54:26 -07:00
smack lsm/stable-6.12 PR 20240923 2024-09-24 10:18:15 -07:00
tomoyo tomoyo: fallback to realpath if symlink's pathname does not exist 2024-09-25 22:30:59 +09:00
yama sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
commoncap.c lsm: Refactor return value of LSM hook vm_enough_memory 2024-07-31 14:46:51 -04:00
device_cgroup.c
inode.c lsm: Use IS_ERR_OR_NULL() helper function 2024-08-29 11:12:13 -04:00
Kconfig lsm/stable-6.12 PR 20240911 2024-09-16 18:19:47 +02:00
Kconfig.hardening Revert "mm: init_mlocked_on_free_v3" 2024-06-15 10:43:05 -07:00
lsm_audit.c
lsm_syscalls.c lsm: use 32-bit compatible data types in LSM syscalls 2024-03-14 11:31:26 -04:00
Makefile lsm: add IPE lsm 2024-08-19 22:36:26 -04:00
min_addr.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
security.c bpf-next-6.12-struct-fd 2024-09-24 14:54:26 -07:00