• Linus Torvalds's avatar
    Merge branch 'next-lockdown' of... · aefcf2f4
    Linus Torvalds authored
    Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
    Pull kernel lockdown mode from James Morris:
     "This is the latest iteration of the kernel lockdown patchset, from
      Matthew Garrett, David Howells and others.
      From the original description:
        This patchset introduces an optional kernel lockdown feature,
        intended to strengthen the boundary between UID 0 and the kernel.
        When enabled, various pieces of kernel functionality are restricted.
        Applications that rely on low-level access to either hardware or the
        kernel may cease working as a result - therefore this should not be
        enabled without appropriate evaluation beforehand.
        The majority of mainstream distributions have been carrying variants
        of this patchset for many years now, so there's value in providing a
        doesn't meet every distribution requirement, but gets us much closer
        to not requiring external patches.
      There are two major changes since this was last proposed for mainline:
       - Separating lockdown from EFI secure boot. Background discussion is
         covered here: https://lwn.net/Articles/751061/
       -  Implementation as an LSM, with a default stackable lockdown LSM
          module. This allows the lockdown feature to be policy-driven,
          rather than encoding an implicit policy within the mechanism.
      The new locked_down LSM hook is provided to allow LSMs to make a
      policy decision around whether kernel functionality that would allow
      tampering with or examining the runtime state of the kernel should be
      The included lockdown LSM provides an implementation with a simple
      policy intended for general purpose use. This policy provides a coarse
      level of granularity, controllable via the kernel command line:
      Enable the kernel lockdown feature. If set to integrity, kernel features
      that allow userland to modify the running kernel are disabled. If set to
      confidentiality, kernel features that allow userland to extract
      confidential information from the kernel are also disabled.
      This may also be controlled via /sys/kernel/security/lockdown and
      overriden by kernel configuration.
      New or existing LSMs may implement finer-grained controls of the
      lockdown features. Refer to the lockdown_reason documentation in
      include/linux/security.h for details.
      The lockdown feature has had signficant design feedback and review
      across many subsystems. This code has been in linux-next for some
      weeks, with a few fixes applied along the way.
      Stephen Rothwell noted that commit 9d1f8be5 ("bpf: Restrict bpf
      when kernel lockdown is in confidentiality mode") is missing a
      Signed-off-by from its author. Matthew responded that he is providing
      this under category (c) of the DCO"
    * 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (31 commits)
      kexec: Fix file verification on S390
      security: constify some arrays in lockdown LSM
      lockdown: Print current->comm in restriction messages
      efi: Restrict efivar_ssdt_load when the kernel is locked down
      tracefs: Restrict tracefs when the kernel is locked down
      debugfs: Restrict debugfs when the kernel is locked down
      kexec: Allow kexec_file() with appropriate IMA policy when locked down
      lockdown: Lock down perf when in confidentiality mode
      bpf: Restrict bpf when kernel lockdown is in confidentiality mode
      lockdown: Lock down tracing and perf kprobes when in confidentiality mode
      lockdown: Lock down /proc/kcore
      x86/mmiotrace: Lock down the testmmiotrace module
      lockdown: Lock down module params that specify hardware parameters (eg. ioport)
      lockdown: Lock down TIOCSSERIAL
      lockdown: Prohibit PCMCIA CIS storage when the kernel is locked down
      acpi: Disable ACPI table override if the kernel is locked down
      acpi: Ignore acpi_rsdp kernel param when the kernel has been locked down
      ACPI: Limit access to custom_method when the kernel is locked down
      x86/msr: Restrict MSR access when the kernel is locked down
      x86: Lock down IO port access when the kernel is locked down