Messages in this thread |  | | Date | Mon, 19 Aug 2002 06:59:02 -0700 | From | "H. Peter Anvin" <> | Subject | Re: klibc and logging |
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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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