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    SubjectRe: SECURITY PROBLEM: filesystem permiossion bypass on FD already opened
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    NiTRo  wrote:
    > Just discovered this security problem [...]
    >If a FD is opened on a allowed file and then the permission is changed
    >the file is still redeable starting from the already read position to
    >the EOF.

    This is not a security problem; this is Unix working as designed.
    That's how file descriptors work. File permissions are checked when
    the file is opened, not on every read/write to the file descriptor.
    That's a pretty fundamental aspect of how Unix works, and it is
    well-documented and well-understood.

    On the other hand, the /proc attack that Pavel explains *is* a
    security problem. But that's different.


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