On 09/09/2013 08:49 AM, Matthew Garrett wrote: > Provide a coarse-grained runtime configuration option for restricting > userspace's ability to modify the running kernel. > > Signed-off-by: Matthew Garrett <matthew.garrett@xxxxxxxxxx> > --- > Documentation/security/securelevel.txt | 23 +++++++ > include/linux/security.h | 8 +++ > security/Kconfig | 8 +++ > security/Makefile | 1 + > security/securelevel.c | 116 +++++++++++++++++++++++++++++++++ > 5 files changed, 156 insertions(+) > create mode 100644 Documentation/security/securelevel.txt > create mode 100644 security/securelevel.c > > diff --git a/Documentation/security/securelevel.txt b/Documentation/security/securelevel.txt > new file mode 100644 > index 0000000..a1355a0 > --- /dev/null > +++ b/Documentation/security/securelevel.txt > @@ -0,0 +1,23 @@ > +Linux securelevel interface > +--------------------------- > + > +The Linux securelevel interface (inspired by the BSD securelevel interface) > +is a runtime mechanism for configuring coarse-grained kernel-level security > +restrictions. It provides a runtime configuration variable at > +/sys/kernel/security/securelevel which can be written to by root. The > +following values are supported: > + > +-1: Permanently insecure mode. This level is equivalent to level 0, but once > + set cannot be changed. > + > +0: Insecure mode (default). This level imposes no additional kernel > + restrictions. > + > +1: Secure mode. If set, userspace will be unable to perform direct access > + to PCI devices, port IO access, access system memory directly via > + /dev/mem and /dev/kmem, perform kexec_load(), use the userspace > + software suspend mechanism, insert new ACPI code at runtime via the > + custom_method interface or modify CPU MSRs (on x86). Certain drivers > + may also limit additional interfaces. > + This will break or have to be redefined once you have signed kexec. -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
