Dynamic Root Support For FreeBSD Now Available

Dan writes "FreeBSD's Gordon Tetlow has committed his enhancements to enable users to build /bin and /sbin dynamically linked on FreeBSD. His reason to do this is two-fold. One is to give better support for PAM and NSS in the base system. The second is to save some disk space. Currently (on his x86 box), /bin and /sbin are 32 MB. With a dynamically linked root (and some pruning of some binaries), the /bin, /lib, and /sbin come out to 6.1 MB. This should be great for people with 2.x and 3.x era root partitions that are only about 50 MB. Gordon says that there will be a performance hit associated with this. He did a quick measurement at boot and his boot time (from invocation of /etc/rc to the login prompt) went from 12 seconds with a static root to 15 seconds with a dynamic root."

Comments

Re:bad bad bad

[Nizzt]

Thats why the librarys are in /lib not /usr/lib

Re:bad bad bad

[cperciva]

it will also make it impossible to recover a server if you accidentally delete /usr

No. The libraries used by stuff in /bin and /sbin are being moved into /lib, so everything which is being changed from static to dynamic will still work even if /usr is gone.

Also note that /rescue is still static (and crunched).

good and bad here

[josepha48]

This is good in the case of people who want to run a system off a cdrom or floppy or flash memory. On a cdrom you don't need to worry about deleteing /usr cause it should be burned into the cdrom. Also any partitions that you need end up in ram / memory disks. /dev is a good example of a ram disk. By having a smaller /bin and /sbin one can suddenly have nice small routers / gateways using freebsd, instead of Linux.

I'd imagine that if NetBSD and OpenBSD don't already have this ability it will be a matter of time as the BSD's share much between each other. Just look at the realpath vulnerability that they all were affected by.

Re:bad bad bad

[shlong]

" not only will this affect performance, but it will also make it impossible to recover a server if you accidentally delete /usr,"

What wasn't mentioned in the write-up is that /rescue contains statically-link versions of the tools that one would need to recover from problems. It might not be able to recover a deleted filesystem, but if you're trouncing careless around like that then there are plenty of other ways to shoot your feet off too.