On Wed 2014-07-23 14:10:16, Hannes Frederic Sowa wrote: > > > On Wed, Jul 23, 2014, at 13:52, George Spelvin wrote: > > I keep wishing for a more general solution. For example, some way to > > have a "spare" extra fd that could be accessed with a special O_NOFAIL > > flag. > > > > That would allow any number of library functions to not fail, such as > > logging from nasty corner cases. > > > > But you'd have to provide one per thread, and block non-fatal signals > > while it was open, so you don't get reentrancy problems. Ick. > > > > > > This overly-specialized system call (and worse yet, a blocking > > system call that you can't put into a poll() loop) just feels ugly > > to me. Is it *absolutely* necessary? > > One point that often came up besides fd exhaustion is missing > /dev/u?random device nodes in chroot environments. >From the maillist discussion, it seems you sometimes _want_ /dev/random not to be present. For example you want to trace exactly the same path through malware every time. > > For example, how about simply making getentropy() a library function that > > aborts if it can't open /dev/urandom? If you're suffering fd exhaustion, > > you're being DoSed already. > > Maybe applications want to mitigate fd exhaustion. Dunno. Will we add special read_passwd() syscall that reads just /etc/passwd, to allow uid<->name resolution without available FDs? I like the library function suggestion, this should not need a new syscall. And btw -- compatibility with getentropy() is _not_ going to be easy, if they have different blocking / partial read / signals policy. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
