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    SubjectRe: [RFC] correct flags to f_mode conversion in __dentry_open
    On Wed, Mar 12, 2008 at 02:25:27PM -0400, Eric Paris wrote:
    > I recently tried to add an SELinux BUG_ON in the case where the kernel
    > made a permission request for no permissions and was able to stumble
    > over it with something as simple as
    >
    > open("/dev/null", 3);
    >
    > Notice that 3 == (O_RDWR | O_WRONLY)
    >
    > First question, is 3 ever a valid flag from from userspace to sys_open?

    Yes. "Check for both read and write permissions, set neither FMODE_READ
    nor FMODE_WRITE".

    Don't break drivers, please - some use that for "ioctl-only" opens,
    with special semantics for those.


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