From: Linus Torvalds <torvalds@linux-foundation.org> To: "Theodore Y. Ts'o" <tytso@mit.edu> Cc: "Ahmed S. Darwish" <darwish.07@gmail.com>, Andreas Dilger <adilger.kernel@dilger.ca>, Jan Kara <jack@suse.cz>, Ray Strode <rstrode@redhat.com>, William Jon McCann <mccann@jhu.edu>, zhangjs <zachary@baishancloud.com>, linux-ext4@vger.kernel.org, lkml <linux-kernel@vger.kernel.org> Subject: Re: Linux 5.3-rc8 Date: Wed, 11 Sep 2019 17:45:38 +0100 Message-ID: <CAHk-=whW_AB0pZ0u6P9uVSWpqeb5t2NCX_sMpZNGy8shPDyDNg@mail.gmail.com> (raw) In-Reply-To: <20190911160729.GF2740@mit.edu> On Wed, Sep 11, 2019 at 5:07 PM Theodore Y. Ts'o <tytso@mit.edu> wrote: > > > > Ted, comments? I'd hate to revert the ext4 thing just because it > > happens to expose a bad thing in user space. > > Unfortuantely, I very much doubt this is going to work. That's > because the add_disk_randomness() path is only used for legacy > /dev/random [...] > > Also, because by default, the vast majority of disks have > /sys/block/XXX/queue/add_random set to zero by default. Gaah. I was looking at the input randomness, since I thought that was where the added randomness that Ahmed got things to work with came from. And that then made me just look at the legacy disk randomness (for the obvious disk IO reasons) and I didn't look further. > So the the way we get entropy these days for initializing the CRNG is > via the add_interrupt_randomness() path, where do something really > fast, and we assume that we get enough uncertainity from 8 interrupts > to give us one bit of entropy (64 interrupts to give us a byte of > entropy), and that we need 512 bits of entropy to consider the CRNG > fully initialized. (Yeah, there's a lot of conservatism in those > estimates, and so what we could do is decide to say, cut down the > number of bits needed to initialize the CRNG to be 256 bits, since > that's the size of the CHACHA20 cipher.) So that's 4k interrupts if I counted right, and yeah, maybe Ahmed was just close enough before, and the merging of the inode table IO then took him below that limit. > Ultimately, though, we need to find *some* way to fix userspace's > assumptions that they can always get high quality entropy in early > boot, or we need to get over people's distrust of Intel and RDRAND. Well, even on a PC, sometimes rdrand just isn't there. AMD has screwed it up a few times, and older Intel chips just don't have it. So I'd be inclined to either lower the limit regardless - and perhaps make the "user space asked for randomness much too early" be a big *warning* instead of being a basically fatal hung machine? Linus
next prev parent reply index Thread overview: 211+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <CAHk-=whBQ+6c-h+htiv6pp8ndtv97+45AH9WvdZougDRM6M4VQ@mail.gmail.com> 2019-09-10 4:21 ` Ahmed S. Darwish 2019-09-10 11:33 ` Linus Torvalds 2019-09-10 12:21 ` Linus Torvalds 2019-09-10 17:33 ` Ahmed S. Darwish 2019-09-10 17:47 ` Reindl Harald 2019-09-10 18:21 ` Linus Torvalds 2019-09-11 16:07 ` Theodore Y. Ts'o 2019-09-11 16:45 ` Linus Torvalds [this message] 2019-09-11 17:00 ` Linus Torvalds 2019-09-11 17:36 ` Theodore Y. Ts'o 2019-09-12 3:44 ` Ahmed S. Darwish 2019-09-12 8:25 ` Theodore Y. Ts'o 2019-09-12 11:34 ` Linus Torvalds 2019-09-12 11:58 ` Willy Tarreau 2019-09-14 12:25 ` [PATCH RFC] random: getrandom(2): don't block on non-initialized entropy pool Ahmed S. Darwish 2019-09-14 14:08 ` Alexander E. Patrakov 2019-09-15 5:22 ` [PATCH RFC v2] random: optionally block in getrandom(2) when the CRNG is uninitialized Theodore Y. Ts'o 2019-09-15 8:17 ` [PATCH RFC v3] random: getrandom(2): optionally block when " Ahmed S. Darwish 2019-09-15 8:59 ` Lennart Poettering 2019-09-15 9:30 ` Willy Tarreau 2019-09-15 10:02 ` Ahmed S. Darwish 2019-09-15 10:40 ` Willy Tarreau 2019-09-15 10:55 ` Ahmed S. Darwish 2019-09-15 11:17 ` Willy Tarreau 2019-09-15 17:32 ` [PATCH RFC v2] random: optionally block in getrandom(2) when the " Linus Torvalds 2019-09-15 18:32 ` Willy Tarreau 2019-09-15 18:36 ` Willy Tarreau 2019-09-15 19:08 ` Linus Torvalds 2019-09-15 19:18 ` Willy Tarreau 2019-09-15 19:31 ` Linus Torvalds 2019-09-15 19:54 ` Willy Tarreau 2019-09-15 18:59 ` Linus Torvalds 2019-09-15 19:12 ` Willy Tarreau 2019-09-16 2:45 ` Ahmed S. Darwish 2019-09-16 18:08 ` Lennart Poettering 2019-09-16 19:16 ` Willy Tarreau 2019-09-18 21:15 ` [PATCH RFC v4 0/1] random: WARN on large getrandom() waits and introduce getrandom2() Ahmed S. Darwish 2019-09-18 21:17 ` [PATCH RFC v4 1/1] " Ahmed S. Darwish 2019-09-18 23:57 ` Linus Torvalds 2019-09-19 14:34 ` Theodore Y. Ts'o 2019-09-19 15:20 ` Linus Torvalds 2019-09-19 15:50 ` Linus Torvalds 2019-09-20 13:13 ` Theodore Y. Ts'o 2019-09-19 20:04 ` Linus Torvalds 2019-09-19 20:45 ` Alexander E. Patrakov 2019-09-19 21:47 ` Linus Torvalds 2019-09-19 22:23 ` Alexander E. Patrakov 2019-09-19 23:44 ` Alexander E. Patrakov 2019-09-20 13:16 ` Theodore Y. Ts'o 2019-09-23 11:55 ` David Laight 2019-09-20 13:08 ` Theodore Y. Ts'o 2019-09-20 13:46 ` Ahmed S. Darwish 2019-09-20 14:33 ` Andy Lutomirski 2019-09-20 16:29 ` Linus Torvalds 2019-09-20 17:52 ` Andy Lutomirski 2019-09-20 18:09 ` Linus Torvalds 2019-09-20 18:16 ` Willy Tarreau 2019-09-20 19:12 ` Andy Lutomirski 2019-09-20 19:51 ` Linus Torvalds 2019-09-20 20:11 ` Alexander E. Patrakov 2019-09-20 20:17 ` Matthew Garrett 2019-09-20 20:51 ` Andy Lutomirski 2019-09-20 22:44 ` Linus Torvalds 2019-09-20 23:30 ` Andy Lutomirski 2019-09-21 3:05 ` Willy Tarreau 2019-09-21 6:07 ` Florian Weimer 2019-09-23 18:33 ` Andy Lutomirski 2019-09-26 21:11 ` Ahmed S. Darwish 2019-09-20 18:12 ` Willy Tarreau 2019-09-20 19:22 ` Andy Lutomirski 2019-09-20 19:37 ` Willy Tarreau 2019-09-20 19:52 ` Andy Lutomirski 2019-09-20 20:02 ` Linus Torvalds 2019-09-20 18:15 ` Alexander E. Patrakov 2019-09-20 18:29 ` Andy Lutomirski 2019-09-20 17:26 ` Willy Tarreau 2019-09-20 17:56 ` Ahmed S. Darwish 2019-09-26 20:42 ` [PATCH v5 0/1] random: getrandom(2): warn on large CRNG waits, introduce new flags Ahmed S. Darwish 2019-09-26 20:44 ` [PATCH v5 1/1] " Ahmed S. Darwish 2019-09-26 21:39 ` Andy Lutomirski 2019-09-28 9:30 ` Ahmed S. Darwish 2019-09-14 15:02 ` Linux 5.3-rc8 Ahmed S. Darwish 2019-09-14 16:30 ` Linus Torvalds 2019-09-14 16:35 ` Alexander E. Patrakov 2019-09-14 16:52 ` Linus Torvalds 2019-09-14 17:09 ` Alexander E. Patrakov 2019-09-14 19:19 ` Linus Torvalds 2019-09-15 6:56 ` Lennart Poettering 2019-09-15 7:01 ` Willy Tarreau 2019-09-15 7:05 ` Lennart Poettering 2019-09-15 7:07 ` Willy Tarreau 2019-09-15 8:34 ` Lennart Poettering 2019-09-15 17:02 ` Linus Torvalds 2019-09-16 3:23 ` Theodore Y. Ts'o 2019-09-16 3:40 ` Linus Torvalds 2019-09-16 3:56 ` Linus Torvalds 2019-09-16 17:00 ` Theodore Y. Ts'o 2019-09-16 17:07 ` Linus Torvalds 2019-09-14 21:11 ` Ahmed S. Darwish 2019-09-14 22:05 ` Martin Steigerwald 2019-09-14 22:24 ` Theodore Y. Ts'o 2019-09-14 22:32 ` Linus Torvalds 2019-09-15 1:00 ` Theodore Y. Ts'o 2019-09-15 1:10 ` Linus Torvalds 2019-09-15 2:05 ` Theodore Y. Ts'o 2019-09-15 2:11 ` Linus Torvalds 2019-09-15 6:33 ` Willy Tarreau 2019-09-15 6:53 ` Willy Tarreau 2019-09-15 6:51 ` Lennart Poettering 2019-09-15 7:27 ` Ahmed S. Darwish 2019-09-15 8:48 ` Lennart Poettering 2019-09-15 16:29 ` Linus Torvalds 2019-09-16 1:40 ` Ahmed S. Darwish 2019-09-16 1:48 ` Vito Caputo 2019-09-16 2:49 ` Theodore Y. Ts'o 2019-09-16 4:29 ` Willy Tarreau 2019-09-16 5:02 ` Linus Torvalds 2019-09-16 6:12 ` Willy Tarreau 2019-09-16 16:17 ` Linus Torvalds 2019-09-16 17:21 ` Theodore Y. Ts'o 2019-09-16 17:44 ` Linus Torvalds 2019-09-16 17:55 ` Serge Belyshev 2019-09-16 19:08 ` Willy Tarreau 2019-09-16 23:02 ` Matthew Garrett 2019-09-16 23:05 ` Linus Torvalds 2019-09-16 23:11 ` Matthew Garrett 2019-09-16 23:13 ` Alexander E. Patrakov 2019-09-16 23:15 ` Matthew Garrett 2019-09-16 23:18 ` Linus Torvalds 2019-09-16 23:29 ` Ahmed S. Darwish 2019-09-17 1:05 ` Linus Torvalds 2019-09-17 1:23 ` Matthew Garrett 2019-09-17 1:41 ` Linus Torvalds 2019-09-17 1:46 ` Matthew Garrett 2019-09-17 5:24 ` Willy Tarreau 2019-09-17 7:33 ` Martin Steigerwald 2019-09-17 8:35 ` Willy Tarreau 2019-09-17 8:44 ` Martin Steigerwald 2019-09-17 12:11 ` Theodore Y. Ts'o 2019-09-17 12:30 ` Ahmed S. Darwish 2019-09-17 12:46 ` Alexander E. Patrakov 2019-09-17 12:47 ` Willy Tarreau 2019-09-17 16:08 ` Lennart Poettering 2019-09-17 16:23 ` Linus Torvalds 2019-09-17 16:34 ` Reindl Harald 2019-09-17 17:42 ` Lennart Poettering 2019-09-17 18:01 ` Linus Torvalds 2019-09-17 20:28 ` Martin Steigerwald 2019-09-17 20:52 ` Ahmed S. Darwish 2019-09-17 21:38 ` Martin Steigerwald 2019-09-17 21:52 ` Matthew Garrett 2019-09-17 22:10 ` Martin Steigerwald 2019-09-18 13:53 ` Lennart Poettering 2019-09-19 7:28 ` Martin Steigerwald 2019-09-17 23:08 ` Linus Torvalds 2019-09-18 13:40 ` Lennart Poettering 2019-09-17 20:58 ` Linus Torvalds 2019-09-18 9:33 ` Rasmus Villemoes 2019-09-18 10:16 ` Willy Tarreau 2019-09-18 10:25 ` Alexander E. Patrakov 2019-09-18 10:42 ` Willy Tarreau 2019-09-18 19:31 ` Linus Torvalds 2019-09-18 19:56 ` Eric W. Biederman 2019-09-18 20:13 ` Linus Torvalds 2019-09-18 20:15 ` Alexander E. Patrakov 2019-09-18 20:26 ` Linus Torvalds 2019-09-18 22:12 ` Willy Tarreau 2019-09-27 13:57 ` Lennart Poettering 2019-09-27 15:58 ` Linus Torvalds 2019-09-29 9:05 ` Lennart Poettering 2019-09-17 13:11 ` Alexander E. Patrakov 2019-09-17 13:37 ` Alexander E. Patrakov 2019-09-17 15:57 ` Lennart Poettering 2019-09-17 16:21 ` Willy Tarreau 2019-09-17 17:13 ` Lennart Poettering 2019-09-17 17:29 ` Willy Tarreau 2019-09-17 20:42 ` Martin Steigerwald 2019-09-18 13:38 ` Lennart Poettering 2019-09-18 13:59 ` Alexander E. Patrakov 2019-09-18 14:50 ` Alexander E. Patrakov 2019-09-17 20:36 ` Martin Steigerwald 2019-09-17 16:27 ` Linus Torvalds 2019-09-17 16:34 ` Matthew Garrett 2019-09-17 17:16 ` Willy Tarreau 2019-09-17 17:20 ` Matthew Garrett 2019-09-17 17:23 ` Matthew Garrett 2019-09-17 17:57 ` Willy Tarreau 2019-09-17 16:58 ` Alexander E. Patrakov 2019-09-17 17:30 ` Lennart Poettering 2019-09-17 17:32 ` Willy Tarreau 2019-09-17 17:41 ` Alexander E. Patrakov 2019-09-17 17:28 ` Lennart Poettering 2019-09-17 0:03 ` Matthew Garrett 2019-09-17 0:40 ` Matthew Garrett 2019-09-17 7:15 ` a sane approach to random numbers (was: Re: Linux 5.3-rc8) Martin Steigerwald 2019-09-16 18:00 ` Linux 5.3-rc8 Alexander E. Patrakov 2019-09-16 19:53 ` Ahmed S. Darwish 2019-09-17 15:32 ` Lennart Poettering 2019-09-16 3:31 ` Linus Torvalds 2019-09-23 20:49 ` chaos generating driver was " Pavel Machek 2019-09-14 9:25 ` Ahmed S. Darwish 2019-09-14 16:27 ` Theodore Y. Ts'o 2019-09-11 21:41 ` Ahmed S. Darwish 2019-09-11 22:37 ` Ahmed S. Darwish 2019-09-16 3:52 ` Herbert Xu 2019-09-16 4:21 ` Linus Torvalds 2019-09-16 4:53 ` Willy Tarreau 2019-09-10 11:56 ` Theodore Y. Ts'o 2019-09-16 10:33 ` Christoph Hellwig 2019-10-03 21:10 ` Jon Masters 2019-10-03 21:31 ` Jon Masters
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