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jitterentropy-rngd decreases available entropy on arm64 #19
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Am Donnerstag, dem 11.03.2021 um 16:43 -0800 schrieb Djhg2000:
Tested on Mobian Unstable (Debian Sid based distribution targeting phones),
`jitterentropy-rngd` squashes the available entropy (read from
`/proc/sys/kernel/random/entropy_avail`) to a single digit number (in one of
my test runs down from `383` to `2`). Output sample below:
I am wondering whether the rngd is the cuplrit here. It sounds more like that
there is a user space component wanting data from /dev/random that commonly
stalls as insufficient entropy is available . But with the rngd, you get
sufficient entropy which may unblock this process sooner and thus pull random
data that draws down the entropy counter.
```
$ sudo jitterentropy-rngd -vvvv
jitterentropy-rngd - Debug: Injected 64 bytes with an entropy count of 32
bytes of entropy
jitterentropy-rngd - Verbose: 64 bytes written to /dev/random
jitterentropy-rngd - Debug: Install termination signal handler
jitterentropy-rngd - Debug: Install alarm signal handler
jitterentropy-rngd - Debug: Polling /dev/random
jitterentropy-rngd - Verbose: Wakeup call for select on /dev/random
jitterentropy-rngd - Debug: Injected 64 bytes with an entropy count of 32
bytes of entropy
jitterentropy-rngd - Verbose: 64 bytes written to /dev/random
jitterentropy-rngd - Debug: Polling /dev/random
jitterentropy-rngd - Verbose: Wakeup call for select on /dev/random
jitterentropy-rngd - Debug: Injected 64 bytes with an entropy count of 32
bytes of entropy
jitterentropy-rngd - Verbose: 64 bytes written to /dev/random
```
Last 4 lines repeats very quickly and easily fills the entire console buffer
in under a second.
This sounds very much like the scenario I describe above.
The issue is not repeatable on Debian Sid running on amd64.
I guess this is because the offending user space process does not exist there.
…
Both systems are running version `1.2.1-1` from the official Debian
repositories.
|
I'd just like to add from my own testing (on the pinephone): |
Am Freitag, 12. März 2021, 18:40:23 CET schrieb fortysixandtwo:
Hi fortysixandtwo,
That is indeed an odd behavior. This sounds like what is discussed in issue
#20.
Can you try the debug hints stated there?
When you say you start the jitterentropy-rngd in a second window, do you have
then two rngd instances running?
Which kernel do you use?
My problem is that I cannot reproduce the issue and now we need to pinpoint
the issue you see.
Ciao
Stephan
|
Am Freitag, 12. März 2021, 01:43:15 CET schrieb Djhg2000:
Hi Djhg2000,
can you please try the latest code in the git repo to see whether this
addresses the issue you see?
Thanks
Stephan
|
It does indeed sound a lot like #20 , I'll give the latest git a try and report back. |
Latest git solves the issue on Mobian. Mobian Unstable is using Linux kernel 5.11.6 so I think it's safe to say this and #20 is a duplicate issue (we just didn't know it earlier). |
Am Montag, dem 15.03.2021 um 08:08 -0700 schrieb Djhg2000:
Latest git solves the issue on Mobian. Mobian Unstable is using Linux kernel
5.11.6 so I think it's safe to say this and #20 is a duplicate issue (we
just didn't know it earlier).
Thank you - let me keep the issue open until a true release is published.
Ciao
Stephan
|
The new code has been released |
Tested on Mobian Unstable (Debian Sid based distribution targeting phones),
jitterentropy-rngd
squashes the available entropy (read from/proc/sys/kernel/random/entropy_avail
) to a single digit number (in one of my test runs down from383
to2
). Output sample below:Last 4 lines repeats very quickly and easily fills the entire console buffer in under a second. The issue is not repeatable on Debian Sid running on amd64.
Both systems are running version
1.2.1-1
from the official Debian repositories.The text was updated successfully, but these errors were encountered: