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crypto: aes - Fix conditions for selecting MAC dependencies

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Starting in commit 7137cbf2b5 ("crypto: aes - Add cmac, xcbc, and
cbcmac algorithms using library"), the aes module (CRYPTO_AES) supports
CBC based MACs using the corresponding library functions.

To avoid including unneeded functionality, that support honors the
existing CRYPTO_CMAC, CRYPTO_XCBC, and CRYPTO_CCM kconfig options.  The
dependencies are selected if at least one of those is enabled.

However, the select statements don't correctly handle the case where
CRYPTO_AES=y and (for example) CRYPTO_CMAC=m.  In that case the
dependencies get selected at level 'm', due to how the kconfig language
works.  That causes a linker error.

Fix this by changing the selection conditions to use '!= n'.

A similar issue also exists for CRYPTO_LIB_AES's conditional selection
of CRYPTO_LIB_UTILS.  The same '!= n' would work, but instead just make
CRYPTO_LIB_AES always select CRYPTO_LIB_UTILS.  CRYPTO_LIB_UTILS is
lightweight, and it's needed by most AES modes and many other things.

Fixes: 7137cbf2b5 ("crypto: aes - Add cmac, xcbc, and cbcmac algorithms using library")
Fixes: 309a7e514d ("lib/crypto: aes: Add support for CBC-based MACs")
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260709022954.45113-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
This commit is contained in:
Eric Biggers
2026-07-08 22:29:54 -04:00
parent 9665e22579
commit e073f1238e
2 changed files with 3 additions and 4 deletions
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4
crypto/Kconfig
View File

@@ -358,8 +358,8 @@ config CRYPTO_AES
tristate "AES (Advanced Encryption Standard)"
select CRYPTO_ALGAPI
select CRYPTO_LIB_AES
select CRYPTO_LIB_AES_CBC_MACS if CRYPTO_CMAC || CRYPTO_XCBC || CRYPTO_CCM
select CRYPTO_HASH if CRYPTO_CMAC || CRYPTO_XCBC || CRYPTO_CCM
select CRYPTO_LIB_AES_CBC_MACS if CRYPTO_CMAC != n || CRYPTO_XCBC != n || CRYPTO_CCM != n
select CRYPTO_HASH if CRYPTO_CMAC != n || CRYPTO_XCBC != n || CRYPTO_CCM != n
help
AES cipher algorithms (Rijndael)(FIPS-197, ISO/IEC 18033-3)

3
lib/crypto/Kconfig
View File

@@ -8,8 +8,7 @@ config CRYPTO_LIB_UTILS
config CRYPTO_LIB_AES
tristate
# Select dependencies of modes that are part of libaes.
select CRYPTO_LIB_UTILS if CRYPTO_LIB_AES_CBC_MACS
select CRYPTO_LIB_UTILS
config CRYPTO_LIB_AES_ARCH
bool