Re: [AppArmor 39/45] AppArmor: Profile loading and manipulation,pathname matching

From: david
Date: Sat Jun 09 2007 - 13:33:57 EST

On Sat, 9 Jun 2007, Kyle Moffett wrote:

On Jun 09, 2007, at 12:46:40, david@xxxxxxx wrote:
On Sat, 9 Jun 2007, Kyle Moffett wrote:
> Typical "targetted" policies leave all user logins as unrestricted, > adding security for daemons but not getting in the way of users who would > otherwise turn SELinux off. On the other hand, a targeted policy has a > "trusted" type for user logins which is explicitly allowed access to > everything.

Ok, it sounds as if I did misunderstand SELinux. I thought that by labeling the individual files you couldn't do the 'only restrict apache' type of thing.

> That said, if you actually want your system to *work* with any > default-deny policy then you have to describe EVERYTHING anyways. How > exactly do you expect AppArmor to "work" if you don't allow users to run > "/bin/passwd", for example.

for AA you don't try to define permissions for every executable, and ones that you don't define policy are unrestricted.

so as I understand this with SELinux you will have lots of labels around your system (more as you lock down the system more) you need to define policy so that your unrestricted users must have access to every label, and every time you create a new label you need to go back to all your policies to see if the new label needs to be allowed from that policy

Actually, it's easier than that. There are type attributes which may be assigned to an arbitrary set of types, and each "type" field in an access rule may use either a type or an attribute. So you don't actually need to modify existing rules when adding new types, you just add the appropriate existing attributes to your new type. For example, you could set up a "logfile" attribute which allows logrotate to archive old versions and allows audit-admin users to modify/delete them, then whenever you need to add a new logfile you just declare the "my_foo_log_t" type to have the "logfile" attribute.

isn't this just the flip side of the same problem?

every time you define a new attribute you need to go through all the files and decide if the new attribute needs to be given to that file.

David Lang

On the other hand, I seem to recall that typical "targeted" policies don't grant most of the additional access via access rules, they instead add a special case to the fundamental "constraints" in the policy (IE: If the subject type has the "trusted" attribute then skip some of the other type-based checks).

Kyle Moffett

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at