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authorKees Cook <keescook@chromium.org>2016-04-20 15:46:28 -0700
committerJames Morris <james.l.morris@oracle.com>2016-04-21 10:47:27 +1000
commit9b091556a073a9f5f93e2ad23d118f45c4796a84 (patch)
tree075fffff80b5caad9738f633c83333dea9e04efd /Documentation/security
parent1284ab5b2dcb927d38e4f3fbc2e307f3d1af9262 (diff)
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LSM: LoadPin for kernel file loading restrictions
This LSM enforces that kernel-loaded files (modules, firmware, etc) must all come from the same filesystem, with the expectation that such a filesystem is backed by a read-only device such as dm-verity or CDROM. This allows systems that have a verified and/or unchangeable filesystem to enforce module and firmware loading restrictions without needing to sign the files individually. Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: James Morris <james.l.morris@oracle.com>
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+LoadPin is a Linux Security Module that ensures all kernel-loaded files
+(modules, firmware, etc) all originate from the same filesystem, with
+the expectation that such a filesystem is backed by a read-only device
+such as dm-verity or CDROM. This allows systems that have a verified
+and/or unchangeable filesystem to enforce module and firmware loading
+restrictions without needing to sign the files individually.
+
+The LSM is selectable at build-time with CONFIG_SECURITY_LOADPIN, and
+can be controlled at boot-time with the kernel command line option
+"loadpin.enabled". By default, it is enabled, but can be disabled at
+boot ("loadpin.enabled=0").
+
+LoadPin starts pinning when it sees the first file loaded. If the
+block device backing the filesystem is not read-only, a sysctl is
+created to toggle pinning: /proc/sys/kernel/loadpin/enabled. (Having
+a mutable filesystem means pinning is mutable too, but having the
+sysctl allows for easy testing on systems with a mutable filesystem.)