x86/intel_rdt: Protect against resource group changes during locking

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We intend to modify file permissions to make the "tasks", "cpus", and
"cpus_list" not accessible to the user when cache pseudo-locking in
progress. Even so, it is still possible for the user to force the file
permissions (using chmod) to make them writeable. Similarly, directory
permissions will be modified to prevent future monitor group creation but
the user can override these restrictions also.

Add additional checks to the files we intend to restrict to ensure that no
modifications from user space are attempted while setting up a
pseudo-locking or after a pseudo-locked region is set up.

Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: fenghua.yu@intel.com
Cc: tony.luck@intel.com
Cc: vikas.shivappa@linux.intel.com
Cc: gavin.hindman@intel.com
Cc: jithu.joseph@intel.com
Cc: dave.hansen@intel.com
Cc: hpa@zytor.com
Link: https://lkml.kernel.org/r/0c5cb006e81ead0b8bfff2df530c5d3017fd31d1.1529706536.git.reinette.chatre@intel.com

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This commit is contained in:

Reinette Chatre 2018-06-22 15:42:12 -07:00 • committed by Thomas Gleixner

parent 125db711e3

commit c966dac8a5

2 changed files with 38 additions and 4 deletions

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10

arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c

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32

arch/x86/kernel/cpu/intel_rdt_rdtgroup.c

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