new open_port hook

From: Matthew J. Fanto (mattjf@private)
Date: Mon Mar 01 2004 - 17:38:04 PST

  • Next message: Chris Wright: "Re: new open_port hook" 

    I've been speaking to Chris Wright about read-only /dev/kmem in an LSM.
Current solutions (grsecurity for example) just return -EPERM inside
drivers/char/mem.c::open_port(). We had a discussion about the nature of
CAP_SYS_RAWIO, and have come to a few conclusions. Replacing calls to
capable(CAP_SYS_RAWIO) would be problematic because we wouldn't know the
context of the call to offer fine grained control. The only solutions we
have come up with is either controlling /dev/kmem access through
inode_permissions() or by adding a new hook that open_port() can call.
The problem I see with inode_permissions() is the overhead of checking
to see if it's /dev/kmem on every inode access. Would a new hook for
open_port() be accepted? Is anyone aware of any other solution? Thanks. 

-Matthew J. Fanto

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