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    SubjectRe: klibc and logging
    Russell King wrote:
    > On Tue, Aug 13, 2002 at 12:12:10AM -0700, H. Peter Anvin wrote:
    >
    >>However, I'm wondering what to do about logging.
    >
    >
    > While writing my scripts for initramfs, the following thought occurred:
    >
    > 1. We only need the fd for initramfs.
    > 2. We want to log the output from commands executed in initramfs.
    >
    > Currently with an initrd, we set fd 0, 1, 2 to point to /dev/console.
    > Is there any reason we couldn't set fd 0 to /dev/console (maybe from
    > inside initramfs) but always setup fd 1 and 2 from the kernel to point
    > at a special "translate this into printk" fd ?
    >
    > This has several advantages:
    >
    > 1. No need for another "special" device.
    > 2. Once the fd is closed, its gone for good - no security concerns with
    > apps in userland after boot dumping copious amounts of data into the
    > kernel message buffer.
    > 3. initramfs programs/scripts don't need to be aware of any special
    > logging facilities
    >
    > The disadvantages:
    >
    > 1. We need some way to open fd 1 and 2 in the first place; this is
    > likely to be a special case, and initramfs is supposed to remove
    > special cases from the kernel.
    >

    I really think this is a bad idea. The kmsg device has different
    properties -- for example, you're supposed to tag things with the
    message importance. It really matches the syslog(3) interface better.
    Also, the special case makes me nervous.

    The "DoS opportunity" is a complete and utter red herring. If you have
    permission to write /dev/kmsg then you have permission to write
    /dev/kmem too!

    -hpa

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