Messages in this thread | | | From | "Paul Fulghum" <> | Subject | tty_io.c 8k write limit | Date | Fri, 13 Aug 1999 11:21:16 -0500 |
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In the file drivers/char/tty_io.c, the higher level tty code has a function do_tty_write which does nothing but break up writes into maximum size of 2 pages before passing the write to the line discipline.
The only comment for the code says:
/* * Split writes up in sane blocksizes to avoid * denial-of-service type attacks */
I have a driver and line discipline for synchronous HDLC applications that interprets each individual write as a whole frame. This works fine unless you want to send a frame larger than 2 pages.
My question is: is this write break up really needed? I'm not sure what DOS attack is prevented with this code.
Would anyone object to either increasing the maximum size to 64K (our device supports 64Kbyte frames) *OR* introducing a tty flag that would cause the write to be passed in whole to the line discipline. The line discipline could set/clear this flag when it is selected/deselected. This way the behavior is not changed unless the line discipline requires it.
Paul Fulghum paulkf@microgate.com Microgate Corporation www.microgate.com 9501 Capital of Texas Hwy Austin, Texas 78759 (512)-345-7791
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