Messages in this thread |  | | Date | Mon, 22 Jul 1996 23:15:31 -0400 | From | "Theodore Y. Ts'o" <> | Subject | Re: Dumping /dev/zero to the console |
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From: lilo <TaRDiS@mail.utexas.edu> Date: Sun, 21 Jul 1996 10:44:25 -0500 (CDT)
/dev/zero can be used for a variety of things. It contains no sensitive information (only binary zeroes :) and hence conceptually its access should not be restricted.
There are a lot of other denial-of-service attacks that users can employ on Linux. If there's any interest in reducing the effectiveness of denial-of-service attacks (and improving Linux's handling of resource-exhaustion situations) that might be a better approach than simply denying access to this device.
It's also not hard thwart fix this sort of denial-of-service attack; just put in code to periodically check to see if need_resched is true, and call schedule() to yield control of the process. You should also check to see if a signal has been posted, and exit appropriately:
if (need_resched) schedule(); if (current->signal & ~current->blocked) return (bytes_written ? bytes_written : -ERESTARTSYS);
Any kernel system call which might be long-lived should definitely be doing something like this, just for robustness's sake.
- Ted
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