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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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1234567891011121314151617181920212223242526272829303132=======LoadPin=======
LoadPin is a Linux Security Module that ensures all kernel-loaded files(modules, firmware, etc) all originate from the same filesystem, withthe expectation that such a filesystem is backed by a read-only devicesuch as dm-verity or CDROM. This allows systems that have a verifiedand/or unchangeable filesystem to enforce module and firmware loadingrestrictions without needing to sign the files individually.
The LSM is selectable at build-time with ``CONFIG_SECURITY_LOADPIN``, andcan be controlled at boot-time with the kernel command line option"``loadpin.enforce``". By default, it is enabled, but can be disabled atboot ("``loadpin.enforce=0``").
LoadPin starts pinning when it sees the first file loaded. If theblock device backing the filesystem is not read-only, a sysctl iscreated to toggle pinning: ``/proc/sys/kernel/loadpin/enabled``. (Havinga mutable filesystem means pinning is mutable too, but having thesysctl allows for easy testing on systems with a mutable filesystem.)
It's also possible to exclude specific file types from LoadPin using kernelcommand line option "``loadpin.exclude``". By default, all files areincluded, but they can be excluded using kernel command line option suchas "``loadpin.exclude=kernel-module,kexec-image``". This allows to usedifferent mechanisms such as ``CONFIG_MODULE_SIG`` and``CONFIG_KEXEC_VERIFY_SIG`` to verify kernel module and kernel image whilestill use LoadPin to protect the integrity of other files kernel loads. Thefull list of valid file types can be found in ``kernel_read_file_str``defined in ``include/linux/kernel_read_file.h``.