From: Jacob Potter Date: Tue, 16 Dec 2008 16:47:58 +0000 (-0500) Subject: documentation work X-Git-Url: http://git.joshuawise.com/netwatch.git/commitdiff_plain/c00c1c15f28f3d926d9ce500417265f8afe72eca?ds=sidebyside;hp=-c documentation work --- c00c1c15f28f3d926d9ce500417265f8afe72eca diff --git a/README b/README new file mode 100644 index 0000000..2977c05 --- /dev/null +++ b/README @@ -0,0 +1,52 @@ +NetWatch! + + This is NetWatch, a system for remote system-management-mode-based +control of a machine without support from or awareness by the OS. It works by +taking over a second network card to provide a standard VNC server, such that +a machine elsewhere on the network can see the text or graphics console of the +machine and inject keystrokes as needed. + + . + + . + + Because NetWatch is invisible to the OS, its CPU usage is difficult to +monitor; we do so by comparing the MD5 throughput of the system with NetWatch +running versus without. The only way that the OS could detect this performance +drain is by spinning tightly and watching for a sudden jump in the CPU's time +stamp counters. + + Although it would be possible to start up NetWatch after an OS kernel +has already loaded, it is easier and more useful to load it from GRUB before +the OS boots, such that even the bootloader itself can be controlled over the +network. We do this by providing a stub loader (grubload/) which can be invoked +from GRUB, and takes care of loading the main NetWatch ELF image. Once this is +done and NetWatch is up and running, the loader returns to real mode and +reinvokes GRUB via the BIOS. + + Our current development platform, the Intel ICH2, does not allow SMM +traps on arbitrary PCI accesses. This makes stealing the network card from the +OS somewhat difficult, since there is nothing SMM code can do to cleanly block +access. NetWatch simply chooses its desired network card, and then repeatedly +clobbers the PCI base address registers. Although Linux resets the BARs to sane +values when it probes the PCI bus, by the time it attempts to actually load +the network driver, the card will no longer be accessible; fortunately, the +driver quickly gives up, and Linux no longer attempts to access the card. + + The northbridge can be configured to invoke a system management +interrupt every 64 milliseconds, and so the bulk of NetWatch's work is done +from this interrupt: checking the network card for incoming packets, invoking +lwIP, and sending any response packets necessary. SMM entry also occurs when +when the OS reads from the keyboard I/O ports, to inject scan codes as needed. + + Much of NetWatch is very hardware-dependent, and although we've tried +to maintain clean interface separation to allow for easy porting, the current +implementation requires: + + - Intel ICH2 system chipset + - 3C509 Ethernet card to be used by NetWatch, plus another card of + any type for the OS + - BIOS which does not set the D_LCK bit. Any system old enough to be + based on the ICH2 is very likely to have a suitable BIOS. + + Current open issues are listed in the TODO file. diff --git a/TODO b/TODO index 7a77450..1892de9 100644 --- a/TODO +++ b/TODO @@ -1,22 +1,9 @@ -To do list: -[ ] Spin the fans! - Requested by de0u 9/11/2008 -[ ] Twice weekly backup into AFS - Requested by de0u 9/11/2008 -[ ] Code & data size (kloc) for IP, and for VNC estimate / project - presentation - Requested by de0u 9/11/2008 -[ ] Fix ACPI (0xB2/B3 emulation -- can we fake it?) -[.] PCI scan / module instantiation -[.] Refactor smram_* - First cut at splitting out ICH2 code done by jdpotter 9/12/2008 - PCI scan can be done later -[.] Update blog as needed -[X] Refactor SMI management (moving it all out to an ich2/x.c would be fine - as pass 1 -- later it can use the PCI scan) -[ ] Synchronize headers -[ ] Fix build system... -[X] Something has gone very wrong with the receive ring buffer, and on - occasion, the machine stops receiving forever. - fixed a few hours later... -[ ] 'unknown TNT2 format ff', then a hang still happens on occasion +Todo list as of 20081216: + +- Support formats other than RGB888 +- Support password-based (or better) VNC authentication. +- Automatically switch GRUB from the loader to the actual kernel +- Fix ridiculously slow video checksumming (i.e. make X usable) +- Make ACPI work? +- "Unknown TNT2 format ff" hang occasionally happens during startx +- Figure out why traps cause lockup in SMM.