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    SubjectRe: [PATCH] in-core AFS multiplexor and PAG support
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    > Right, if some process/user opens a file and then passes the descriptor
    > to another process/user which closes it. The close should operate under
    > the same permissions as the original opener.

    As long as the token isn't explicitly withdrawn. With my token structure, I've
    defined it such that if the list_head in the token struct is ever empty, then
    the token is withdrawn.

    Furthermore, I'm considering it such that the the filesystem will select a
    token from the PAG's token ring in the file_operations->open method and will
    attach it to the file->f_token at that point for quick reference later.

    > If someone obtains my user id on in any way (i.e. weak password/
    > bufferoverflow/ root exploit), he should not be allowed to use or access
    > my tokens as he hasn't proven his identity. In this case he would either
    > still be in his original process authentication group, or a new and
    > empty PAG. But definitely not in any of my authentication groups.
    >
    > Which is also why joining a PAG should never be allowed.

    Someone asked for it, but I suspect if allowed at all it may be best that this
    ability is governed by its own capability bit and also that the security
    interface should be consulted.

    David
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