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Differential D53150

random: add RDSEED as a provably unique entropy source
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Authored by obrien on Oct 17 2025, 5:48 AM.
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csprng
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rG1b7bd82b6dcc: random: add RDSEED as a provably unique entropy source
rG9ca8e09abba8: random: add RDSEED as a provably unique entropy source
rG3a12982962ce: random: add RDSEED as a provably unique entropy source
Summary

NIST SP800-90B allows for only a single entropy source to be claimed
in a FIPS-140-3 certificate. In addition, only hardware sources that
have a NIST Entropy Source Validation (ESV) certificate, backed by
a SP800-90B Entropy Assessment Report, are usable. Intel has obtained
ESV certificates for several of their processors, so RDSEED is a
FIPS-140-3 suitable entropy source.

However, even though RDRAND is seeded by RDSEED internally, RDRAND
would need a RBG certificate and CAVP testing run on the DRBG in order
to use it for FIPS-140-3 (SP800-90B) purposes. So we need to know
down in the CSPRNG-subsystem which source the entropy came from.

In light of the potential issues surrounding AMD Zen 5 CPU's RDSEED
implementation[*], allow RDSEED to be disabled in loader.conf.

Diff Detail

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rG FreeBSD src repository
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Buildable 67979
Build 64862: arc lint + arc unit

Event Timeline

obrien created this revision.Oct 17 2025, 5:48 AM
Herald added a subscriber: imp. · View Herald TranscriptOct 17 2025, 5:48 AM
obrien requested review of this revision.Oct 17 2025, 5:48 AM
Harbormaster completed remote builds in B67846: Diff 164367.Oct 17 2025, 5:48 AM
obrien updated this revision to Diff 164368.Oct 17 2025, 5:50 AM

tags

Harbormaster completed remote builds in B67847: Diff 164368.Oct 17 2025, 5:50 AM
obrien updated this revision to Diff 164369.Oct 17 2025, 6:01 AM

modules

Harbormaster completed remote builds in B67848: Diff 164369.Oct 17 2025, 6:01 AM
obrien added a reviewer: csprng.Oct 18 2025, 12:07 AM
cem accepted this revision.Oct 20 2025, 3:35 PM
cem added a subscriber: cem.

Unobjectionable. Mechanical changes LGTM.

sys/dev/random/ivy.c
2

Might be nice to rename "ivy" to "rdrand" while you're at it.

94–95

I think you can kill the IFUNC in both, given each module only has one happy path now.

You'd need to move the cpu feature checks somewhere else; modevent() is probably fine.

sys/dev/random/random_harvestq.c
669

Also ABI breaking, for whatever that's worth

sys/dev/random/rdseed.c
84–85

Ditto

This revision is now accepted and ready to land.Oct 20 2025, 3:35 PM
obrien marked an inline comment as done.Oct 21 2025, 4:17 PM
obrien added inline comments.
sys/dev/random/ivy.c
2

I'd rather just leave the filename alone for now.

sys/dev/random/random_harvestq.c
669

I'm adding bumping __FreeBSD_version. Though I'm not really worried about it. I don't know of any out-of-tree modules that provide entropy to /dev/random. Mixing new kernel w/out-of-date in-tree modules seems very fragile and something I double anyone tries to do.

obrien updated this revision to Diff 164717.Oct 21 2025, 9:38 PM

embelish based on review comments

This revision now requires review to proceed.Oct 21 2025, 9:38 PM
Harbormaster completed remote builds in B67979: Diff 164717.Oct 21 2025, 9:38 PM
obrien edited the summary of this revision. (Show Details)Oct 21 2025, 9:40 PM
This revision was not accepted when it landed; it landed in state Needs Review.Oct 22 2025, 7:07 AM
Closed by commit rG3a12982962ce: random: add RDSEED as a provably unique entropy source (authored by obrien). · Explain Why
This revision was automatically updated to reflect the committed changes.
obrien added a commit: rG3a12982962ce: random: add RDSEED as a provably unique entropy source.
obrien added a commit: rG9ca8e09abba8: random: add RDSEED as a provably unique entropy source.Oct 29 2025, 7:01 AM
cperciva added a commit: rG1b7bd82b6dcc: random: add RDSEED as a provably unique entropy source.Nov 3 2025, 8:29 PM

Revision Contents
Changeset List

PathSize
sys/
conf/
1 line
dev/
random/
69 lines
1 line
137 lines
modules/
2 lines
rdrand_rng/
5 lines
rdseed_rng/
9 lines
sys/
2 lines
1 line

Diff 164717

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sys/conf/files.x86

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sys/dev/random/ivy.c

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sys/dev/random/random_harvestq.c

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sys/dev/random/rdseed.c

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sys/modules/Makefile

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sys/modules/rdrand_rng/Makefile

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sys/modules/rdseed_rng/Makefile

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sys/sys/param.h

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sys/sys/random.h

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