Messages in this thread |  | | | Date | Tue, 19 May 1998 22:07:23 +0200 | | From | Pavel Machek <> | | Subject | Signal security |
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Hi!
On linux, any user may kill setuid program he ran with any signal. I think that this is dangerous:
Consider user running passwd, waiting to just right moment, and then killing passwd with SIGKILL (which it can not block). There even was talk about that on bugtraq: they used it to simulate flood ping without needing uid==0:
while [ true ]; do killall -14 ping; done
I'm afraid that there are more "creative" way to use this feature.
BSD solved by only allowing you to send certain signals (that generated from keyboard) to programs with different euid but same real uid.
I took a look at kernel/signal.c - it is understandable but as this is really security-sensitive area I'm asking first.
Pavel
-- I'm really pavel@atrey.karlin.mff.cuni.cz. Pavel Look at http://atrey.karlin.mff.cuni.cz/~pavel/ ;-).
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