[PATCH v2] seedrng: limit poolsize to 256 bytes and document flock() and fsync() usage

[Jason A. Donenfeld]

On Sat, Apr 30, 2022 at 11:19 PM Denys Vlasenko
<vda.linux at googlemail.com> wrote:
> Thank you for the explanation. I re-adding the fsync
> and adding a comment. Please take a look at current git.

Oh god, what have you done? You have butchered seedrng into garbage. I
do not agree with the changes you made. You've removed important error
handling in ways that make certain intended use cases absolutely
impossible. Please revert your changes, which you made mid-discussion
here with no agreement reached. Then you can interact on the mailing
list by sending patches and discussing them. If not -- if you want to
keep tumbling down this monstrous route that you're on -- my
participation here ends entirely, and my advice will be to avoid
busybox because its maintainer is a wreckless cowboy.

Just from a cursory look:

- You removed the return value check on fsync(dfd), which means the
check is worthless and introduces a security vulnerability.
- You haven't responded to my messages regarding the importance of
returning proper error codes and appear to have removed them entirely
now?
- Your comment about reads from /dev/urandom depleting the entropy
pool isn't correct. (Plus you used an inconsistent type of comment
with bad indentation. Did you even check your work?)
- You completely ignored the `MAX_SEED_LEN = 256` change from the
patch that this thread is actually about, which means there's no
resolution for that issue. Plus you didn't respond to my email where I
discussed various solutions for that matter. Did you read the patch I
sent?

Jason