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James Morris
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Below are the 10 most recent journal entries recorded in the "James Morris" journal:
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12:24 pm
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Sliding into SELinux Policy Development with Fedora 9
In case you hadn't noticed, Fedora 9 has been released. One of the many goodies to be included is SLIDE: the SELinux policy development IDE. This should be great news for application developers who want their projects to work well with SELinux.
It's been possible for some time now to quickly develop a loadable policy module when an application clashes with the shipped SELinux policy. The technique is quite simple: parse the audit log and generate rules which allow the previously denied accesses. This is a form of "learning mode", which risks encapsulating badness and being incomplete. It's often handy for resolving local issues, but not necessarily the kind of thing that a developer would want to use for creating shippable and maintainable policy.
This is where SLIDE comes in. It's an eclipse-based environment with deep knowledge of the SELinux policy infrastructure, facilitating policy development for everything from the simplest application through to the general system policy. It's not "SELinux policy for Dummies", but it does provide some useful high-level abstractions such as wizards. Developers who are interested in learning more about how to develop policy for their applications can now easily get started with SLIDE in Fedora 9. If not installed already, do so:
$ sudo yum install eclipse-slide selinux-policy-devel
SLIDE should then be available via Applications -> Programming -> Eclipse. Start a new project and follow the prompts to create a policy module for an application. The application doesn't even need to exist—this is simply a good way to learn about the policy framework. Note that the location of reference policy is /usr/share/selinux/devel/include.
Here are some screenshots (click for larger images):
Creating a new policy module via the wizard.
Guided interface. These fields are automatically populated, while elements may be expanded out for greater control.
Automatically generated initial policy ready for building or further development.
It would be immensely useful now to have a simple worked tutorial to help people get started in a practical manner. I'm not sure if anyone is planning to do this currently, so if you're looking for a way to dive in and contribute to the project, please get in touch via the mailing list. Otherwise, please wait until it falls from the sky.
Have fun!
Tags: developers, eclipse, fedora, fedora9, flask, fmac, foss, ide, linux, mac, mandatory access control, policy, security, selinux, slide, sulphur, type enforcement
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10:00 am
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Linux on Mumbai City Buses
Via a the Chennai ILUG mailing list, here's an interesting story: Linux rides pillion on Mumbai city buses. I like how this system uses GPS to figure the cost of each trip, rather than alternatives such as a single fare or complicated fare schemes.
Deployed in January 2007, the system is so stable that it will this month be officially extended to part of Mumbai's suburban railways as well. It is also secure, and has had no hacks and cracks, according to Kaizen.
Thanks to the system's use of Linux, BEST saved about inr 1.2 million on the point of sale infrastructure alone, as compared with a Microsoft Windows setup, Goriani says.
It's also slightly reassuring to see they're moved from telnet to SSH for remote management.
Sydney recently canned a smartcard-based bus ticketing system after spending AUD$95 million. Given that the same company was developing both systems (as well as the system for Singapore), and that such systems are fairly commonplace in modern cities, I think you could reasonably surmise that the problems in the Sydney system were not technical.
Tags: bus, centos, india, linux, mumbai, smartcard, sydney, transportation
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09:35 am
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Labeled NFS Requirements Draft Submitted
Dave Quigley has just submitted an Internet Draft to the IETF outlining the requirements for Labeled NFS:
MAC Security Label Requirements for NFSv4 (link)
Abstract
This Internet-Draft outlines high-level requirements for the
integration of flexible Mandatory Access Control (MAC) functionality
into NFSv4.1 . It describes the level of protections that should be
provided over protocol components and the basic structure of the
proposed system. It also gives a brief explanation of what kinds of
protections MAC systems offer and why existing NFSv4 protection
mechanisms are not sufficient.
This draft is a generalization the original Security Enhanced NFS document posted last year, addressing the general need for mandatory access control support in NFS.
NFSv4 currently supports two access control schemes: standard DAC and ACLs. MAC labeling support is required for technologies such as SELinux and OpenSolaris FMAC.
Essentially what's needed is a way to convey MAC labels over the wire (for both setting and retrieving their values), and to be able to enforce security policy using those labels. The server needs to be able to determine the security label of the remote client process when enforcing policy, and all systems need to be able to ensure they understand each other's labels, or be able to translate them. A "Domain of Interpretation" (DOI) attribute is used to determine the meaning of labels, a term which may be familiar to those who've braved the IPsec specifications. The confidentiality and integrity of these security attributes must be protected in transit, while all parties need to be authenticated. We also need to be able to handle the case where either the client or server does not have MAC enabled, and to ensure non-breakage with existing implementations. There's a lot more in the details, but that's the gist of it.
It may seem at first glance that NFSv4 named attributes (NAs) would provide the required labeling functionality, but they're not a good fit. NAs are specifed as opaque to the system and user-managed, while MAC security labels are managed by the system. NAs also do not provide necessary semantics such as conveying client security attributes or negotiation of DOI. There are also issues with attribute namespaces (which are user-managed and unspecified) and labeling atomicity. Another possible approach is to implement Linux/BSD-style extended attributes (EAs), which are simple text string attributes associated with files, in contrast with the NA "subfile" scheme. This would potentially only solve the attribute namespace issue, and is also not a good general solution. EAs are also not currently part of the NFSv4 specification, and it seems like a contentious area in any case.
The current Labeled NFS prototype code utilizes NFSv4 recommended attributes (RAs), which are fully extensible, already exist, and are already used for similar management of metadata (e.g. ACLs). This seems to be the simplest and most straightforward approach.
Once there's consensus on the requirements, the next step will be to develop a protocol specification and hopefully have it incorporated into NFSv4. v4.1 is currently in "last call", so the next candidate would be v4.2, it seems. The prototype code for Linux/SELinux will continue to be developed alongside the standards process.
For those interested in following or contributing to the project, there are several relevant mailing lists:
Dave is hoping to have further discussion IETF 72 in July, and will be presenting on the state of the project at the SELinux Developer Summit ahead of that.
Tags: developers, flask, fmac, foss, ietf, kernel, labeled nfs, linux, mac, mandatory access control, opensolaris, security, selinux, type enforcement
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11:09 am
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2008 SELinux Developer Summit Schedule Now Up
We managed to get the SELinux developer summit schedule published a few days early. Hopefully, this will help people who are making travel arrangements to OLS.
As mentioned, a lot of high quality proposals were submitted. To ensure that all important topics can be covered, the format of the summit has been changed to moderated discussion panels with presentations; rather than the original plan of having a set of fixed-length presentations followed by discussion panels.
Presentations will now be 10-20 minutes, with a greater focus on discussion. This provides much more flexibility, and is derived somewhat from experience with the kernel networking summit, which has been very successful with short presentations driving discussions.
The panel sessions are as follows:
- Community
- Applications
- Desktop
- Distributed Technologies
- Policy Configuration
- Policy Infrastructure
- Emerging Technology/Works in Progress
More detailed information, including topics, issues, and links to abstracts may be found at the schedule page. Also see the printable version and the topics page.
All SELinux developers and folk with a technical interest in SELinux and related technologies are welcome to attend. Don't forget that you also need to be registered to attend OLS.
Tags: developers, events, flask, fmac, foss, linux, mandatory access control, ols, opensolaris, ottawa, security, selinux, type enforcement
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09:07 pm
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SELinux Developer Summit: CFP closed
The 2008 SELinux Developer Summit CFP is now closed.
As suspected, most of the proposals arrived at the last possible moment. It looks like we have more proposals than can reasonably fit in one day, so the organizing team now has the interesting task of squeezing as much in as possible without overloading the schedule. This is going to be very difficult, as pretty much all of the submissions are of excellent quality.
In any case, we should have the schedule finalized and published within a week or so.
Tags: developers, events, flask, fmac, foss, linux, ols, opensolaris, ottawa, security, selinux, type enforcement
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10:54 am
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SELinux Developer Summit 2008 Announced
We've just announced the SELinux Developer Summit for 2008, which will be held in Ottawa (as an OLS mini-summit) on July 22nd. A CfP will be issued early next week, where we'll be looking for people to submit talks and panel topics.
In previous years, the project has had the SELinux Symposium, generously run by Tresys, with an invite-only developer summit tacked onto the end.
The new Developer Summit is intended to track with the evolution of SELinux as a wider community project, and we are very pleased to be able to hold an open event this year in conjunction with OLS.
All developers and folk with a strong technical interest in SELinux and related Flask/TE projects are encouraged to attend. Note that attendees need to also be registered for OLS.
There'll be more information on the CfP and schedule soon -- this is something of a heads up for those planning travel and who may be wish to start thinking about presentation and discussion topics.
The organizing team is as follows:
- Serge Hallyn (IBM)
- Paul Moore (HP)
- James Morris (Red Hat)
- Chad Sellers (Tresys)
- Stephen Smalley (NSA)
For more details on the event, including contact details for the team refer to the SELinux Developer Summit page.
So, there'll be quite a lot of SELinux content at OLS, some of which I've previously mentioned. To summarize, in addition to the Developer Summit, there'll be:
Talks:
A tutorial:
A BoF session:
So, if you're involved with SELinux or otherwise interested in it, I'd suggest flying, driving, walking or swimming (I'm pretty sure this is possible) to Ottawa this July.
Tags: developers, events, flask, fmac, linux, mac, mandatory access control, ols, opensolaris, ottawa, security, selinux, type enforcement
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02:47 pm
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I forgot how much fun it is to write a paper
Because the cool kids are doing it, here are photos of the bookshelves above my desk:
 
Click for more detail.
It's really great being able to reach over and grab whatever I need without going anywhere. Some would call it lazy; I'd call it efficient.
Tags: books, bookshelf, bookshelves, geek, kernel, linux, security
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08:58 am
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The Linux Foundation does not speak for me
I'd like to say, somewhat for the sake of the OpenSolaris folk who are currently having a bit of a rough time, that I personally strongly disagree with certain statements coming out of the Linux Foundation, such as those claiming that the "L in LAMP is literal". [1]
Of course, LAMP has long been representative of the concept of a free software stack. The term itself has been tremendously useful as a means to identify an open approach to developing and deploying systems. The L does of course not have to mean Linux any more than the P needs to mean PHP or Perl. Aside from OpenSolaris, there are many good choices for operating systems in an open stack, such as OpenBSD.
While LF is an industry consortium representing several companies and organizations with various interests in Linux, it certainly does not generally represent the Linux community.
As a Linux developer, I'd like to continue to extend support and encouragement to OpenSolaris developers.
I believe that such attacks on other open projects serve to damage the general interests of FOSS. Interestingly, LF has granted itself authority to respond to "competitors’ attacks" [2], a role which is surely undermined by themselves undertaking such attacks, especially on emerging FOSS projects.
References:
[1] http://www.linux-foundation.org/weblogs/amanda/2008/02/17/hey-jonathan-the-l-in-lamp-is-literal/
[2] http://www.linux-foundation.org/en/About
Tags: foss, fud, lamp, linux, linux foundation, opensolaris
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12:53 am
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mmap_min_addr setting may mitigate vmsplice exploit
Rafal Wojtczuk of McAfee Avert Labs posted an interesting analysis of the "qaaz" exploit for the recent vmsplice vulnerabilities.
Since 2.6.23, it has been possible to prevent applications from mapping low pages (to prevent null pointer dereferencing in the kernel) via the /proc/sys/vm/mmap_min_addr sysctl, which sets the minimum address allowed for such mappings.
So, if you have a recent kernel still affected by the vmsplice issue, try:
echo 65536 > /proc/sys/vm/mmap_min_addr
(If it is not already set, of course).
If using SELinux, the system must be running in enforcing mode.
Note that there was a bug in the mmap_min_addr code until 2.6.24-rc5, although I do not believe it affects mitigation of this particular exploit.
Generally, it is a good idea to have mmap_min_addr set, although it is disabled by default in the upstream kernel as it can affect a some applications (e.g. users of vm86 mode such as X).
As SELinux is able to selectively enforce the setting via policy, it can be enabled for the general case on recent SELinux systems. If not using SELinux, processes with CAP_SYS_RAWIO are allowed to bypass the setting.
Tags: linux, mitigation, selinux, vulnerabilities
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12:35 am
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IBM article: Role-based access control in SELinux
Serge Hallyn of IBM and general kernel hacking fame has written a great article on Role-based access control (RBAC) in SELinux.
The article is also something of a tutorial, implementing a security scheme for a simple store cash register system, with downloads available for a Gentoo-based SELinux from Scratch qemu image; and for standard Fedora 8 systems.
It's great to see these kinds of projects coming from the community!
Tags: fedora, gentoo, ibm, linux, rbac, selinux
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