KIST works by computing how much should be allowed to write to the kernel for
a given socket, and then it writes that amount to the outbuf.
The problem is that it could be possible that the outbuf already has lots of
data in it from a previous scheduling round (because the kernel is full/busy
and Tor was not able to flush the outbuf yet). KIST ignores that the outbuf
has been filling (is above its "highwater") and writes more anyway. The end
result is that the outbuf length would exceed INT_MAX, hence causing an
assertion error and a corresponding "Bug()" message to get printed to the
logs.
This commit makes it for KIST to take into account the outbuf length when
computing the available space.
Bug found and patch by Rob Jansen.
Closes#29168. TROVE-2019-001.
Signed-off-by: David Goulet <dgoulet@torproject.org>
Fixes bug 29530, where the LOG_ERR messages were occurring when
we had no configured network, and so we were failing the unit tests
because of the recently-merged #28668.
Bug not in any released Tor.
This test fails in some environments; since the code isn't used in
0.4.0, let's disable it for now.
Band-aid solution for #29534; bug not in any released Tor.
malloc_options needs to be declared extern (and declaring it extern
means we need to initialize it separately)
Fixes bug 29145; bugfix on 0.2.9.3-alpha
Signed-off-by: Kris Katterjohn <katterjohn@gmail.com>
This module is currently implemented to use the same technique as
libottery (later used by the bsds' arc4random replacement), using
AES-CTR-256 as its underlying stream cipher. It's backtracking-
resistant immediately after each call, and prediction-resistant
after a while.
Here's how it works:
We generate psuedorandom bytes using AES-CTR-256. We generate BUFLEN bytes
at a time. When we do this, we keep the first SEED_LEN bytes as the key
and the IV for our next invocation of AES_CTR, and yield the remaining
BUFLEN - SEED_LEN bytes to the user as they invoke the PRNG. As we yield
bytes to the user, we clear them from the buffer.
Every RESEED_AFTER times we refill the buffer, we mix in an additional
SEED_LEN bytes from our strong PRNG into the seed.
If the user ever asks for a huge number of bytes at once, we pull SEED_LEN
bytes from the PRNG and use them with our stream cipher to fill the user's
request.
