86 lines
3.4 KiB
Plaintext
86 lines
3.4 KiB
Plaintext
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Desc: Ideas for future expansion and features
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File: ideas.txt
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Date: 20 October 2003
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Auth: Russell Kroll <rkroll@exploits.org>
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Here are some ideas that have come up over the years but haven't
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been implemented yet. This may be a good place to start if you're
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looking for a rainy day hacking project.
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Non-network "upsmon"
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====================
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Some systems don't want a daemon listening to the network. This can be
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for security reasons, or perhaps because the system has been squashed
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down and doesn't have TCP/IP available. For these situations you could
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run a driver and program that sits on top of the driver socket to do
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local monitoring.
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This also makes monitoring extremely easy to automate - you don't need
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to worry about usernames, passwords or firewalling. Just start a driver
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and drop this program on top of it.
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- Parse ups.conf and open the state socket for a driver
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- Send DUMPALL and enter a select loop
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- Parse SETINFOs that change ups.status
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- When you get OB LB, shut down
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Completely unprivileged upsmon
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==============================
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upsmon currently retains root in a forked process so it can call the
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shutdown command. The only reason it needs root on most systems is that
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only privileged users can signal init or send a message on /dev/initctl.
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In the case of systems running sysvinit (Slackware, others?), upsmon
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could just open /dev/initctl while it has root and then drop it
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completely. When it's time to shut down, fire a control structure at
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init across the lingering socket and tell it to enter runlevel 0.
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This has been shown to work in local tests, but it's not portable. It
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could only be offered as an option for those systems which run that
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flavor of init. It also needs to be tested to see what happens to
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the lingering fd over time, such as when init restarts after an upgrade.
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For other systems, there is always the possibility of having a suid
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program which does nothing but prod init into starting a shutdown. Lock
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down the group access so only upsmon's unprivileged user can access it,
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and make that your SHUTDOWNCMD. Then it could drop root completely.
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Chrooted upsmon
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===============
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upsmon could run the network monitoring part in a chroot jail if it had
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a pipe to another process running outside for NOTIFY dispatches. Such a
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pipe would have to be constructed extremely carefully so an attacker
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could not compromise it from the jailed process.
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A state machine with a tightly defined sequence could do this safely.
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All it has to do is dispatch the UPS name and event type.
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[start] [type] [length] <name> [stop]
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Monitor program with interpreted language
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=========================================
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Once in awhile, I get requests for a way to shut down based on the UPS
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temperature, or ambient humidity, or at a certain battery charge level,
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or any number of things other than an "OB LB" status. It should be
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obvious that adding a way to monitor all of that in upsmon would bloat
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upsmon for all those people who really don't need anything like that.
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A separate program that interprets a list of rules and uses it to
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monitor the UPS equipment is the way to solve this. If you have a
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condition that needs to be tested, add a rule.
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Some of the tools that such a language would need include simple
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greater-than/less-than testing (if battery.charge < 20), equivalence
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testing (if ups.model = "SMART-UPS 700"), and some way to set and clear
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timers.
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Due to the expected size and limited audience for such a program, it
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might have to be distributed separately.
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