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SELinux Mailing ListRe: [Xen-devel] protecting xen startup
From: Luke Kenneth Casson Leighton <lkcl_at_lkcl.net>
Date: Wed, 24 Nov 2004 15:24:02 +0000
okay. that can be dealt with by... (this is speculation, here!) by writing an selinux policy in advance that defines how many virtual machines you have, and creating xen_vm0_t, xen_vm1_t etc. to represent them. you then define what operations can be carried out, and then grant a program the right to perform that operation on SPECIFIC machines. [yes there is a short-hand which allows you to specify an operation be allowed by a program on all machines]. then it would be necessary to modify the linux kernel to call the avc_has_perm() function at the appropriate point to check, at the time that an operation was being done (e.g. read from block device), as to whether that process had the right to perform that operation on that xen virtual machine. in order for this to work, it would be necessary to have a translation mechanism between the numbering xen_vm_0_t etc. and the actual xen virtual machines. looking at avc_has_perm(), you'd need a SID per virtual machine, as the second argument... xen_communication_has_perm(struct task_struct *tsk, struct xen_info *xen, u32 perms) { return avc_has_perm(tsec->sid, xen->sid, SECCLASS_XEN, perms, NULL, NULL);} where xen->sid contains "xen_vm_0_t", "xen_vm_1_t" etc. and tsec->sid contains "xen_xm_bin_t" - representing the xen control binary /usr/bin/xm. the question i can't answer (the bit that i don't quite grok) is how do you get hold of the right xen_info struct and how do you blat the sid into it? l. -- This message was distributed to subscribers of the selinux mailing list. If you no longer wish to subscribe, send mail to majordomo@tycho.nsa.gov with the words "unsubscribe selinux" without quotes as the message.Received on Wed 24 Nov 2004 - 10:13:27 EST |
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Date Posted: Jan 15, 2009 | Last Modified: Jan 15, 2009 | Last Reviewed: Jan 15, 2009 |