But a simple user with no rights can mlock (64kb by default) why a jail would not be able?
From: Xin LI<mailto:delp...@gmail.com> Sent: Thursday, February 2, 2017 1:13 PM To: Pavel Timofeev<mailto:tim...@gmail.com> Cc: Bruno Lauzé<mailto:brunola...@msn.com>; freebsd-current<mailto:firstname.lastname@example.org> Subject: Re: mlock and jail On Thu, Feb 2, 2017 at 7:54 AM, Pavel Timofeev <tim...@gmail.com> wrote: > 2017-02-02 4:31 GMT+03:00 Xin LI <delp...@gmail.com>: >> I like this idea. >> >> Note that potentially your patch would make it possible for a jailed >> root to DoS the whole system by locking too much of pages in memory. >> I think it would be sensible to provide a per-jail flag to enable >> doing it, or better, have some finer grained control (e.g. per jail >> quota of permitted locked pages). >> >> Why did the application want to lock pages in main memory, though? > > For example, this secret management tool > https://www.vaultproject.io/docs/config/ wants to lock memory for > security (surprise) reason. > It's available as security/vault in our ports tree. No it's not surprise but overkill IMHO. Here is why: Locking memory does prevent swapping, but in a typical multi-user system, if an attacker is already able to read swap (keep in mind that disks are by default owned by root and can not be read in a typical setup), then the administrator already have much bigger problem to worry about, and the attacker would have much more powerful tools to steal the secrets. Additionally, if one really cares about safety of swap, they should have used encrypted swap in the first place. On FreeBSD, appending '.eli' to the swap device in fstab (e.g. /dev/ada0p3 -> /dev/ada0p3.eli) would automatically do one-time keyed swapping. Moreover, I don't think it's a good idea to use an application that advocates locking all memory that it owns for "security" reasons: if the application writer does not know which memory pages would contain sensitive information, good chances that the application writer have no idea what is privilege separation and the design they have created could be fundamentally flawed. Cheers, _______________________________________________ email@example.com mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"