linux/include
Nicolai Stange fae198935c crypto: dh - split out deserialization code from crypto_dh_decode()
A subsequent commit will introduce "dh" wrapping templates of the form
"ffdhe2048(dh)", "ffdhe3072(dh)" and so on in order to provide built-in
support for the well-known safe-prime ffdhe group parameters specified in
RFC 7919.

Those templates' ->set_secret() will wrap the inner "dh" implementation's
->set_secret() and set the ->p and ->g group parameters as appropriate on
the way inwards. More specifically,
- A ffdheXYZ(dh) user would call crypto_dh_encode() on a struct dh instance
  having ->p == ->g == NULL as well as ->p_size == ->g_size == 0 and pass
  the resulting buffer to the outer ->set_secret().
- This outer ->set_secret() would then decode the struct dh via
  crypto_dh_decode_key(), set ->p, ->g, ->p_size as well as ->g_size as
  appropriate for the group in question and encode the struct dh again
  before passing it further down to the inner "dh"'s ->set_secret().

The problem is that crypto_dh_decode_key() implements some basic checks
which would reject parameter sets with ->p_size == 0 and thus, the ffdheXYZ
templates' ->set_secret() cannot use it as-is for decoding the passed
buffer. As the inner "dh"'s ->set_secret() will eventually conduct said
checks on the final parameter set anyway, the outer ->set_secret() really
only needs the decoding functionality.

Split out the pure struct dh decoding part from crypto_dh_decode_key() into
the new __crypto_dh_decode_key().

__crypto_dh_decode_key() gets defined in crypto/dh_helper.c, but will have
to get called from crypto/dh.c and thus, its declaration must be somehow
made available to the latter. Strictly speaking, __crypto_dh_decode_key()
is internal to the dh_generic module, yet it would be a bit over the top
to introduce a new header like e.g. include/crypto/internal/dh.h
containing just a single prototype. Add the __crypto_dh_decode_key()
declaration to include/crypto/dh.h instead.

Provide a proper kernel-doc annotation, even though
__crypto_dh_decode_key() is purposedly not on the function list specified
in Documentation/crypto/api-kpp.rst.

Signed-off-by: Nicolai Stange <nstange@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-03-03 10:47:50 +12:00
..
acpi USB/Thunderbolt changes for 5.17-rc1 2022-01-12 11:27:57 -08:00
asm-generic lib/xor: make xor prototypes more friendly to compiler vectorization 2022-02-11 20:39:39 +11:00
clocksource
crypto crypto: dh - split out deserialization code from crypto_dh_decode() 2022-03-03 10:47:50 +12:00
drm
dt-bindings Char/Misc and other driver changes for 5.17-rc1 2022-01-14 16:02:28 +01:00
keys
kunit kunit: replace kernel.h with the necessary inclusions 2022-01-20 08:52:54 +02:00
kvm RISCV: 2022-01-16 16:15:14 +02:00
linux lib/xor: make xor prototypes more friendly to compiler vectorization 2022-02-11 20:39:39 +11:00
math-emu
media
memory
misc
net Networking fixes for 5.17-rc1, including fixes from netfilter, bpf. 2022-01-20 10:57:05 +02:00
pcmcia
ras mm/hwpoison: remove MF_MSG_BUDDY_2ND and MF_MSG_POISONED_HUGE 2022-01-15 16:30:31 +02:00
rdma
scsi Merge branch 'akpm' (patches from Andrew) 2022-01-22 11:28:23 +02:00
soc Networking changes for 5.17. 2022-01-10 19:06:09 -08:00
sound
target
trace fscache fixes 2022-01-22 10:59:32 +02:00
uapi The highlight is the new mount "device" string syntax implemented 2022-01-20 13:46:20 +02:00
vdso
video
xen xen: branch for v5.17-rc1 2022-01-12 16:42:00 -08:00