On Mon, Dec 25, 2017 at 10:07:54AM +0200, Gilad Ben-Yossef wrote: > Hi there, > > I have ran into something I am unsure about regarding the ccree driver > implementation and would love to get some guidance: > > I have assumed, based on previous list correspondence, that both of > the following sequences are legal: > > Scenario A > 1. ahash_request_alloc > 2. ahash_import > > Scenario B > 1. ahash_request_alloc > 2. crypto_ahash_init > 3. ahash_import > > However, I've run into the problem that since ahash_request_alloc does > not zero the allocated request memory > and specifically does not zero the tfm specific context part of it, I > have no way to distinguish between A and B and therefore > if I have any initialization sequence that needs to happen once per > request (DMA buffer allocation and mapping in my > case), I cannot tell if I need to do them in ahash_import callback or not. crypto_ahash_init is not necessary prior to an ahash_import. If crypto_ahash_init does any hardware initialisations, then the same would be needed in ahash_import and crypto_ahash_digest. > So, am I'm missing something here or is the B scenario simply not legal? B is completely legal, just as it would be legal to do this: 1. ahash_request_alloc 2. crypto_ahash_init 3. crypto_ahash_update 4. crypto_ahash_init // discard previous hash state Basically you must not hold onto any permanent state at the end of a hash operation such as init. IOW you cannot expect a hash state to be finalised. Cheers, -- Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
