Bugtraq mailing list archives
Re: Linux inetd..
From: avalon () COOMBS ANU EDU AU (Darren Reed)
Date: Wed, 3 Dec 1997 16:39:03 +1100
In some mail from Alan Cox, sie said:
Now you may be wondering why does a write to the socket returned by accept() generates a SIGPIPE. This bring us to the second issue. It seems that at least under Linux 2.0.X accept will return a socket in the received queue if it is not in the SYN_SENT or SYN_RECV state, even when it has not gone through the ESTABLISHED state. By doing a stealth scan on the port the socket goes from the SYN_RECV state to the CLOSED state. When you try to read from such a socket you get a SIGPIPE. The sematics of Linux's accept seems to be non-standard. I wonder what else breaks by not handling SIGPIPE.On that issue you are a little astray. Linux merely made the window for the inetd problem a bit larger. You can hit a box betwen the accept returning towards user space and the write() with a seperate RST frame regardless of what accept returns. If generic BSD has this missing SIGPIPE I venture to say that if you can hit the precise boundary needed you can bring down inetd there too.
I don't see that being a problem for the BSD inetd as it fork()s before the write and the process which receives the SIGPIPE is a child of inetd, not the master (so to speak). I would have thought the linux one would behave the same. Darren
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