Am Mittwoch, 22. Juni 2016, 15:45:38 schrieb Mat Martineau:

Hi Mat,

quoted

Ok, I'll update the patch.

Thanks, that helps (especially with pkcs1pad).

Tadeusz received the updated patch from me to integrate it into his patch set.

This brings me to another proposal for read buffer sizing: AF_ALG akcipher
can guarantee that partial reads (where the read buffer is shorter than
the output of the crypto op) will work using the same semantics as
SOCK_DGRAM/SOCK_SEQPACKET. With those sockets, as much data as will fit is
copied in to the read buffer and the remainder is discarded.

I realize there's a performance and memory tradeoff, since the crypto
algorithm needs a sufficiently large output buffer that would have to be
created by AF_ALG akcipher. The user could manage that tradeoff by
providing a larger buffer (typically key_size?) if it wants to avoid
allocating and copying intermediate buffers inside the kernel.

How shall the user know that something got truncated or that the kernel 
created memory?

Ciao
Stephan