Commit Graph

4 Commits

Author SHA1 Message Date
Eric Biggers a5e9f55709 crypto: chacha20 - Fix chacha20_block() keystream alignment (again)
In commit 9f480faec5 ("crypto: chacha20 - Fix keystream alignment for
chacha20_block()"), I had missed that chacha20_block() can be called
directly on the buffer passed to get_random_bytes(), which can have any
alignment.  So, while my commit didn't break anything, it didn't fully
solve the alignment problems.

Revert my solution and just update chacha20_block() to use
put_unaligned_le32(), so the output buffer need not be aligned.
This is simpler, and on many CPUs it's the same speed.

But, I kept the 'tmp' buffers in extract_crng_user() and
_get_random_bytes() 4-byte aligned, since that alignment is actually
needed for _crng_backtrack_protect() too.

Reported-by: Stephan Müller <smueller@chronox.de>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2018-09-21 13:24:50 +08:00
Eric Biggers 7660b1fb36 crypto: chacha20 - use rol32() macro from bitops.h
For chacha20_block(), use the existing 32-bit left-rotate function
instead of defining one ourselves.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2018-01-12 23:03:01 +11:00
Eric Biggers 9f480faec5 crypto: chacha20 - Fix keystream alignment for chacha20_block()
When chacha20_block() outputs the keystream block, it uses 'u32' stores
directly.  However, the callers (crypto/chacha20_generic.c and
drivers/char/random.c) declare the keystream buffer as a 'u8' array,
which is not guaranteed to have the needed alignment.

Fix it by having both callers declare the keystream as a 'u32' array.
For now this is preferable to switching over to the unaligned access
macros because chacha20_block() is only being used in cases where we can
easily control the alignment (stack buffers).

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-11-29 17:33:33 +11:00
Theodore Ts'o e192be9d9a random: replace non-blocking pool with a Chacha20-based CRNG
The CRNG is faster, and we don't pretend to track entropy usage in the
CRNG any more.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-07-03 00:57:23 -04:00