NAME
Unix::Pledge - restrict system operations
SYNOPSIS
use Unix::Pledge;
# ...
# Program initializtion, open files, drop privileges, fork, etc
# ...
# Now that we're initialized, limit our process to reading our .profile
pledge("stdio rpath", ["/home/$ENV{USER}/.profile"]);
# Reading user's .profile works as expected
open(my $fd, "<", "/home/$ENV{USER}/.profile");
while(<$fd>) {
print $_;
}
# Trying to open outside whitelisted path fails with file not found
open($fd, "<", "/etc/passwd") or warn $!;
# Trying to write will cause SIGABRT
open($fd, ">", "/home/$ENV{USER}/.profile");
# Abort trap (core dumped)
DESCRIPTION
The current process is forced into a restricted-service operating mode.
A few subsets are available, roughly described as computation, memory
management, read-write operations on file descriptors, opening of files,
networking. In general, these modes were selected by studying the
operation of many programs using libc and other such interfaces, and
setting promises or paths.
Requires that the kernel supports the pledge(2) syscall, which as of
this writing is only available in OpenBSD.
NOTE: As of OpenBSD 5.9 the "whitepaths" parameter is disabled as its
implementation is incomplete. Hopefully this will be rectified by the
6.0 release.
The pledge function takes two parameters: "promises" and "whitepaths".
"Promises" is a space delimited string of modes which the process is
promising that it will stick to from here on out. "Whitepaths" is an
optional array ref parameter that is useful to further limit the process
to operate under specific paths only. Paths that are not under the
whitepath will return ENOENT if you attempt to access them.
Process violations of the previously "pledged" modes will result in your
processing being forcibly terminated via SIGABRT. In this way pledge
serves as a capabilities framework like capsicum, systrace, AppArmor,
etc. The difference is that pledge aims to be very easy to use for the
typical developer to sandbox their process.
Note that restrictions are one way only: you can only increase the
restrictions on your process, not relax them.
ERRORS
Unix::Pledge will croak on any errors.
EXPORT
The "pledge" function is exported by default.
SEE ALSO
For detailed information on pledge, its parameters and errors, please
see the OpenBSD pledge(2) man page
ery=pledge>.
AUTHOR
Richard Farr "<richard@nxbit.io>"
COPYRIGHT AND LICENSE
Copyright (C) 2016 by Richard Farr
This module is licensed under the same terms as Perl itself.