---------- Forwarded message ---------- Date: Fri, 17 Sep 1999 12:32:01 -0400 (EDT) From: Brian F. Feldman <greenat_private> To: hackersat_private Subject: socket buffer DoS/administrative limits Yes folks, it's that time again: time for more administrative limits! I've worked out a resource limit (for FreeBSD in this case, but not non-portable) which allows prevention of DoS by mbuf starvation. Others are working on making the networking code more resilient, while this is a general resource limit which can be used in any case. I've chosen the name "sbsize" (RLIMIT_SBSIZE) for this. Here's what happens with the limit in action (note that the pdksh in use has been patched to include the ulimit): {"/home/green"}$ ulimit -b 2000000 ; ulimit -a | grep sbsize sbsize(bytes) 2000000 {"/home/green"}$ ./testsockbuf socketpair: No buffer space available 14 sockets had been allocated And another DoS attempt has been foiled with administrative limits :) I'm sorry for not having something working sooner, but I ran into the problem of my KASSERT() being tripped, which ended up being caused by me not grokking an evil local define (look for "#define (snd|rcv) "...) correctly. After fixing that, everything is wonderful. The patch, which applies to FreeBSD 4.0-CURRENT, and should be easily portable or backportable, can be found at: http://www.FreeBSD.org/~green/sbsize4.patch -- Brian Fundakowski Feldman \ FreeBSD: The Power to Serve! / greenat_private `------------------------------' To Unsubscribe: send mail to majordomoat_private with "unsubscribe freebsd-hackers" in the body of the message
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