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Creating a SE Linux Chroot environment

Why use a Chroot environment?

A large part of the use of chroot environments is for the purpose of security, it used to be the only way of isolating a user from a section of the files on a server. In many of the cases where a chroot used to be used for security it [...]

SE Linux status in Debian/Squeeze

ffmpeg

I’ve updated my SE Linux repository for Squeeze to include a modified version of the ffmpeg packages without MMX support for the i386 architecture. When MMX support is enabled it uses assembler code which requires text relocations (see Ulrich Drepper’s documentation for the explanation of this [1]). This makes it possible to run programs [...]

SE Linux audit2allow -R and Milter policy

Since the earliest days there has been a command named audit2allow that takes audit messages of operations that SE Linux denied and produces policy that will permit those operations. A lesser known option for this program is the “-R” option to use the interfaces from the Reference Policy (the newer version of the policy that [...]

Tracking down Write/Execute mmap() calls with LD_PRELOAD

One of the access controls in SE Linux is for execmem – which is used to stop processes from creating memory regions that are writable and executable (as they make it easier to compromise programs and get them to execute supplied code). When the SE Linux audit log tells you that a program is attempting [...]

Play Machine Online Again with Xen 4.0

My SE Linux Play Machine [1] has been offline for almost a month (it went offline late May 30 and has just gone online again). It’s the sort of downtime that can happen when you use Debian/Unstable.

For a while I’ve been using a HP E-PC (a SFF desktop system with 256M of RAM and [...]

New SE Linux Policy for Squeeze

I have just uploaded refpolicy version 0.2.20100524-1 to Unstable. This policy is not well tested (a SE Linux policy package ending in “-1” is not something that tends to work well for all people) and in particular lacks testing for Desktop environments. But for servers it should work reasonably well.

I expect to have a [...]

Can you run SE Linux on a Xen Guest?

I was asked “Can you run SELinux on a XEN guest without any problem?“. In a generic sense the answer is of course YES, Xen allows you to run Linux kernels with all the usual range of features and SE Linux isn’t a particularly difficult feature to enable. I do most of my SE Linux [...]

Can SE Linux Implement Traditional Unix Users and Groups?

I was asked by email whether SE Linux could implement traditional Unix users and groups.

The Strictly Literal Answer to that Question

The core of the SE Linux access control is the domain-type model where every process has a domain and every object that a process can access (including other processes) has a type. Domains [...]

Logging in as Root

Martin Meredith wrote a blog post about logging in as root and the people who so strongly advocate against it [1]. The question is whether you should ssh directly to the root account on a remote server or whether you should ssh to a non-root account and use sudo or su to gain administrative privileges.

[...]

UBAC and SE Linux in Debian

A recent development in SE Linux policy is the concept of UBAC (User Based Access Control) which prevents SE Linux users (identitied) from accessing each other’s files.

SE Linux user identities may map 1:1 to Unix users (as was required in the early versions of SE Linux), you might have unique identities for special users [...]