Detecting a chroot jail from within

Question

How can one detect being in a chroot jail without root privileges? Assume a standard BSD or Linux system. The best I came up with was to look at the inode value for \"/\"

Answer 1

I guess it depends why you might be in a chroot, and whether any effort has gone into disguising it.

I'd check /proc, these files are automatically generated system information files. The kernel will populate these in the root filesystem, but it's possible that they don't exist in the chroot filesystem.

If the root filesystem's /proc has been bound to /proc in the chroot, then it is likely that there are some discrepancies between that information and the chroot environment. Check /proc/mounts for example.

Similrarly, check /sys.