grsecurity forums

Hey guys,

i'm a bloody newbie in working with grsecurity. Indeed i red the Gentoo Grsecurity2 QuickStart Guide (since i'm using Hardened Gentoo), Grsecurity ACL docu, and Ch. 3 and 4 of the great Grsecurity Wikibook but i have no practical experience so far.

I compiled the kernel with CONFIG_GRKERNSEC_HARDENED_SERVER=y and CONFIG_GRKERNSEC_IO=y and now i'm experiencing this problem: i've a sane-supported usb scanner on the system and it works pretty well if i execute scanimage directly.
Then i 'installed' scanbuttond, a little binary that executes an action if one of the scanner buttons is used. I use it as a service.

Now i'm totally confused what happens:

scanbuttond: button 1 has been pressed.
kernel: grsec: From 192.168.1.51: denied use of ioperm() by /usr/bin/scanimage[scanimage:20422] uid/euid:0/0 gid/egid:0/0, parent /usr/local/bin/scanfile.sh[scanfile.sh:20421] uid/euid:0/0 gid/egid:0/0
kernel: grsec: From 192.168.1.51: denied use of ioperm() by /usr/bin/scanimage[scanimage:20422] uid/euid:0/0 gid/egid:0/0, parent /usr/local/bin/scanfile.sh[scanfile.sh:20421] uid/euid:0/0 gid/egid:0/0
kernel: grsec: From 192.168.1.51: denied open of /dev/port by /usr/bin/scanimage[scanimage:20422] uid/euid:0/0 gid/egid:0/0, parent /usr/local/bin/scanfile.sh[scanfile.sh:20421] uid/euid:0/0 gid/egid:0/0
scanbuttond: button 1 has been released.

Firstly: the system has the IP 192.168.1.2, my Windows-Client has the IP 192.168.1.51. I'm via SSH connected to the server but -as far as i understand- my Windows-Client has nothing to do with scanbuttond, scanimage or sane. Can you guys explain me this "From 192.168.1.51" part?

Secondly: the ioperm() and /dev/port restrictions follow from CONFIG_GRKERNSEC_IO, right?
/usr/local/bin/scanfile.sh is a shell script i created to get a document scanned and then further processed. As far as i understand it is started by /usr/local/etc/scanbuttond/buttonpressed.sh which itself is started by the scanbuttond binary.
Can i change this behaviour with chpax or another rule modifying tool or do i have to relinquish the IO protection? Or may it be a trusted path problem?

Thanks for any advice

Yes, if you want to use this scanimage software, you'll have to disable CONFIG_GRKERNSEC_IO.

As for the 192.168.1.51, that's part of grsecurity's tagging of IPs to processes. We try to tag the IP address most likely responsible for the creation of a process, or for the current state of a given service. In this case, perhaps you logged in via SSH and ran the command?

-Brad

spender wrote:Yes, if you want to use this scanimage software, you'll have to disable CONFIG_GRKERNSEC_IO.

To my surprise scanimage receives an image despite the grsecurity kernel messages

Regarding the tagging of IPs to processes: how does grsecurity try to fit this? In my case the only purpose of the SSH session was to show me the logfile. The whole scan process was initiated by pressing the scanner button which is monitored by the scanbuttond. No real link to the network

You must have logged in at a previous time -- and perhaps restarted the scanbuttond service?

-Brad

spender wrote:You must have logged in at a previous time -- and perhaps restarted the scanbuttond service?

Yes, you're right: i started the scanlogd-initscript via ssh. Unbelievable that grsecurity goes that far - i'm fascinated