John Baldwin:
The issue found with HT is that the two logical CPUs
on a single core share the same caches and as a result there are ways
for one logical CPU to spy on the activities of the other CPU in the same core.
Robert N M Watson:
It's worth observing that this is a serious vulnerability
across a range of operating systems,
not just FreeBSD.
If you allow untrusted users on the same system as an SSH daemon,
you're at risk,which affects everyone from desktop users, to ISPs,to military end-users.
It's also a very hard problem to solve
-- we're looking at it from the perspective of improving the scheduler,
bringing in OpenSSL updates to limit timing attacks,
and obviously we're hoping that CPU vendors take this
2. We recently read that the fix for the ... (スコア:1)
2. We recently read that the fix for the Hyper-Threading
vulnerability is considered non-trivial. Why is that?
私たちは、最近、Hyper-Threading の脆弱性のための
フィックスが重要であると考えられると読みます。
それはなぜそうですか?
John Baldwin:
The issue found with HT is that the two logical CPUs
on a single core share the same caches and as a result there are ways
for one logical CPU to spy on the activities of the other CPU in the same core.
Re:2. We recently read that the fix for the ... (スコア:1)
It's worth observing that this is a serious vulnerability
across a range of operating systems,
not just FreeBSD.
If you allow untrusted users on the same system as an SSH daemon,
you're at risk,which affects everyone from desktop users, to ISPs,to military end-users.
It's also a very hard problem to solve
-- we're looking at it from the perspective of improving the scheduler,
bringing in OpenSSL updates to limit timing attacks,
and obviously we're hoping that CPU vendors take this
Re:2. We recently read that the fix for the ... (スコア:1)
これが OS をまたいだ脆弱性であり、FreeBSD だけの問題ではないという点は
注目に値します。信用できないユーザが同じシステムに入ることを SSH が許可
しているなら誰でもこの危険にさらされているのであり、デスクトップユーザから、
ISP や軍関係のエンドユーザにまで影響する問題なのです。そしてこれは非常に
難しい問題です。我々はスケジューラを改善するという視点から見たり、OpenSSL
をアップデートしてタイミング攻撃を制限したりしていますし、さらには CPU
ベンダがこの機会をとらえて、こうした問題に対してより堅牢なアーキテクチャを
探るようになってほしいとも願っています。この脆弱性は単にスケジューリングや
暗号やハイパースレッディングの問題というわけではないため、長期的な解決には
多大の労力が必要となるでしょう。