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RFC Context Mounts and Unsupported Contexts

Cory Olmo selinux 1 version In review

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  1. v1 RFC Latest3 patches 3 repliesIn review

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#Subject and filesSizeRepliesApplied
1/3Context Mounts and Unsupported Contexts: kernellinux-2.6.17.i686/security/selinux/hooks.c+33 -33 replies
2/3Context Mounts and Unsupported Contexts: util-linuxmount/mount.c mount/nfsmount.c+103 -120 replies
3/3Context Mounts and Unsupported Contexts: nfs-utilsutils/mount/mount.c utils/mount/nfsmount.c+54 -70 replies

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Cover letter [RFC Patch 0/3] Context Mounts and Unsupported Contexts

This is a potential patch set to correct the collision which is occurring between commas in contexts and the comma delimiter between option values for mount.

The Problem:

If the context option specified to mount contains a comma then the value of the context option will be improperly broken up.

Example:

Using an MCS translation setup with these entries.

s0:c1=PatientRecord
s0:c2=Unclassified
s0:c3=Secret
s0:c4=TopSecret
s0:c1,c3,c4=CompanySecrets

With translations turned off:
mount -t iso9660 /dev/cdrom /media/cdrom -o \
ro,context=system_u:object_r:iso9660_t:s0:c2,c3,c4,exec

The context option that will be interpreted by SeLinux is context=system_u:object_r:iso9660_t:s0:c2

The options that will be passed on to the file system will be ro,c3,c4,exec.

If translations are turned on the context that will be interpreted for the context, system_u:object_r:iso9660_t:Unclassified,Secret,TopSecret, will be system_u:object_r:iso9660_t:Unclassified.

Proposed Solution:

The proposed solution is to allow/require the SeLinux context option specified to mount to use escaped quotes when the context contains a comma. The patches that are included are for the kernel, util-linux, and nfs-utils. They were generated against the following Fedora rawhide rpms util-linux-2.13-0.36, nfs-utils-1.0.9-3, and kernel-2.6.17-1.2528.

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Cory Olmo

Trusted Computer Solutions
www.TrustedCS.com


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