Re: svn commit: r228843 - head/contrib/telnet/libtelnet head/crypto/heimdal/appl/telnet/libtelnet head/include head/lib/libc/gen head/lib/libc/iconv head/lib/libc/include head/lib/libc/net head/libexec...



On Thu, Dec 29, 2011 at 12:15:31PM -0800, Xin Li wrote:
Instead of total disabling we can (by calling rtld function)
restrict dlopen() in ftpd() to absolute path of know safe
directories list like "/etc" "/lib" "/usr/lib" etc.

This just came back to the origin!! These "safe" locations are never
necessarily be safe inside a chroot environment and the issue was
exactly loading a library underneath /lib/.

I just realized that someone have removed some details from my
advisory draft by the way. To clarify: the chroot issue is not about
the usual usage of chroot, but the fact that many chroot setups are
not safe (e.g. "recommended" practice is to create a user writable
directory under the chroot root with everything else read-only).

Unsecure (non-root /lib) may happens by admin mistake which is very
different situation from loading .so from the current (say /incoming/)
directory. We can't provide babysitting for every admin by our code, but
can by our documentation only (probably by repeating the same thing in
ftpd docs and chroot docs). And many admins don't needs babysitting and
may take it as unnecessary restriction.

--
http://ache.vniz.net/
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