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    SubjectRe: /proc parent &proc_root == NULL?
    On Wed, 26 Jan 2005 22:35:18 EST, John Richard Moser said:

    > This particular problem pertains to proc_misc.c and trying to create a
    > hook for some grsecurity protections that alter the modes on certain
    > /proc entries. The chunk of the patch I'm trying to immitate is:

    > + create_seq_entry("cpuinfo", gr_mode, &proc_cpuinfo_operations);
    > +#else
    > create_seq_entry("cpuinfo", 0, &proc_cpuinfo_operations);
    > +#endif

    An alternate way to approach this - leave the permissions alone here.

    And then use the security_ops->inode_permission() hook to do something like:

    if ((inode == cpuinfo) && (current->fsuid))
    return -EPERM;

    Writing the proper tests for whether it's the inode you want and whether to
    give the request the kiss-of-death are left as an excersize for the programmer.. ;)

    You may want to use a properly timed initcall() to create a callback that
    happens after proc_misc_init() happens, but before userspace gets going, and
    walk through the /proc tree at that time and cache info on the files you care
    about, so you don't have to re-walk /proc every time permission() gets called....
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      Last update: 2005-03-22 14:09    [W:0.019 / U:15.820 seconds]
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