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SubjectRe: [PATCH] Capabilities, this time in elf section
You need capabilities directly tied to the UID or you cannot
securely eliminate root from the system. Whether program
capabilities (which HAVE to be a subset of the capabilities
of the owner) exist in the executable or the filesystem does
not change this. One of the capabilities in question is the
ability to override UID/permission protections on files.

***
The possibility of creating a binary that
posseses a capability that the owner does not
is one definition of a security hole.
***

Any given user is going to have a set of "standard capabilities".

- create and modify files owned by the user in directories owned by
the user.
- run binaries that the user/group permissions allow them to run.

An ordinary user is _NOT_ going to be able to set any capabilities
on binaries they create other than those. However, they _may_ create
a binary that has one or both of those capabilities turned off.

A restricted user may have one or both of those capabilities turned off.

A power/admin user may have additional capabilities, for example:

- chown a file not owned by themselves
- run a file that they do not have explicit permission to run,
- perform other file operations where there is not explicit permission,
- open a TCP socket below 1024,
- assign another user the ability to use capabilities that the
assigning user has permission for,
- mount/unmount filesystems

And others.

Many (all?) of these capabilities are currently part of "root", and
are only usable by root or SUID-root programs. For capabilities
to work properly they still need to be tied directly to a user or
you still need root to own and control all binaries that have capabilities
beyond what an ordinary user may do.




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