On 07/01/2019 22:26, Jordan Brown wrote:
[ Off topic for OpenSSL... ]
On 1/7/2019 8:06 AM, Jakob Bohm via openssl-users wrote:
A chroot with no other reason to open /dev/null should not contain that
file name, even on unix-like platforms (least privilege chroot design).
There's always a first reason :-)
But also: /dev/null is part of the definition of UNIX
<http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap10.html#tag_10_01>.
Programs have every right to expect that it will be there. Yes, you
can build a chroot environment that doesn't include it... but then you
can't complain when programs don't work in your environment. You can
also build an environment that doesn't include system libraries, and
there are reasons to do so, but few programs will work in it.
Looking at Solaris, about 15% of the programs in /usr/bin and 5% of
the libraries in /usr/lib have a reference to /dev/null.
The whole point of a chroot jail is to deny a program access to any
and all parts of Unix (and the local flavor) it won't need. For
example, most chroot jails remove /bin/ls, with ftp servers as the
major exception.
Thus /dev/null being part of UNIX/POSIX doesn't say anything about
its availability in chroot jails. Nor does it say anything about
its availability on non-unix platforms, many of which are explicitly
supported by the OpenSSL libraries.
For many programs, it is standard to chroot to a directory with
nothing or almost nothing after loading configuration files, code,
certificates etc. /var/empty and /var/www are common examples.
Enjoy
Jakob
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