On Thu, Aug 30, 2018 at 02:22:22PM +0200, Krzysztof Kozlowski wrote: > Hi, > > I am trying to figure out necessary locking on the driver side of > crypto HW accelerator for symmetric hash (actually: CRC). I > implemented quite simple driver for shash_alg. > > I looked at the docs, I looked at the crypto kcapi core code... and > there is nothing about necessary locking. kcapi does not perform it. > > My HW is quite similar to drivers/crypto/stm32/stm32_crc32.c so it has > only one HW set of registers for dealing with CRC. Or in other words, > only one queue of one element. :) I implemented all shash_alg > callbacks - init(), update(), final()... and also finup() (manually > calling update+final) and digest() (init+update+final). > > Now imagine multiple user-space users of this crypto alg where all of > them call kcapi_md_digest() (so essentially init() -> update() -> > final()). It seems that kcapi does not perform any locking here so at > some point updates from different processes might be mixed with > finals: > > Process A: Process B: > init() > init() > update() > update() > final() > final() > > My findings show that the requests are indeed being mixed with each other... After each operation all state must be stored in the ahash_request object. The next operation should then load the state from the request object into the hardware. Cheers, -- Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
