This is something I spotted while working on AES in various modes for ARM and arm64. The mac80211 aes_cmac code reimplements the CMAC algorithm based on the core AES cipher, which is rather restrictive in how platforms can satisfy the dependency on this algorithm. For instance, SIMD implementations may have a considerable setup time, which cannot be amortized over the entire input when calling into the crypto API one block at a time. Also, it prevents the use of more secure fixed time implementations, since not all AES drivers expose the cipher interface. So switch aes_cmac to use a cmac(aes) shash. This requires a preparatory patch so that we can remove the open coded implementation, which it shares with the fils aead driver. That driver could receive the same treatment, in which case we could replace patch #1 with one that carries it over first. Note that this is an RFC. I have no idea how I would go about testing this code, but I am on a mission to remove as many dependencies on the generic AES cipher as I can. Ard Biesheuvel (2): mac80211: fils_aead: clone shared CMAC functions into private version mac80211: aes-cmac: switch to shash CMAC driver net/mac80211/Kconfig | 1 + net/mac80211/aes_cmac.c | 137 +++++--------------- net/mac80211/aes_cmac.h | 15 +-- net/mac80211/fils_aead.c | 68 ++++++++++ net/mac80211/key.h | 2 +- 5 files changed, 110 insertions(+), 113 deletions(-) -- 2.7.4
