Rusty Russell wrote: > On Friday 16 May 2008 20:49:41 Johannes Berg wrote: >>> + >>> +/* Our random number generator device reads from /dev/urandom into the Guest's >>> + * input buffers. The usual case is that the Guest doesn't want random numbers >>> + * and so has no buffers although /dev/urandom is still readable, whereas >>> + * console is the reverse. >> Is it really a good idea to use the hosts /dev/urandom to fill the >> guests /dev/random? > > Technically it's up to rngd in the guest to decide whether to feed entropy > or not (ie. /dev/urandom or /dev/random). Uhm, no. It's not. Unless the host provides actual entropy information, you have a security hole. > If we use /dev/random in the host, we risk a DoS. But since /dev/random > is 0666 on my system, perhaps noone actually cares? /dev/random = give me actual entropy, if you have some. /dev/urandom = give me what you have, regardless of quality. There is no point in feeding the host /dev/urandom to the guest (except for seeding, which can be handled through other means); it will do its own mixing anyway. The reason to provide anything at all from the host is to give it "golden" entropy bits. -hpa _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/virtualization
