[GIT PULL][SECURITY] Kernel lockdown patches for v5.4

From: James Morris
Date: Tue Sep 10 2019 - 18:01:26 EST

Hi Linus,

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:

1. Separating lockdown from EFI secure boot. Background discussion is
covered here: https://lwn.net/Articles/751061/

2. 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.

A 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 permitted.

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:

lockdown={integrity|confidentiality}

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 9d1f8be5cf42 ("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.

Several simple conflicts have been identified by Stephen in linux-next:

vfs tree:
https://www.lkml.org/lkml/2019/8/12/21

Linus' tree:
https://www.lkml.org/lkml/2019/8/12/26
https://lkml.org/lkml/2019/8/20/1415
https://lore.kernel.org/lkml/20190821130513.0038df28@xxxxxxxxxxxxxxxx/
https://lore.kernel.org/lkml/20190821130957.407d9c10@xxxxxxxxxxxxxxxx/

Keys tree:
https://lore.kernel.org/lkml/20190829150609.7ae3c4ee@xxxxxxxxxxxxxxxx/

Please consider merging for v5.4.


The following changes since commit
0ecfebd2b52404ae0c54a878c872bb93363ada36:

Linux 5.2 (2019-07-07 15:41:56 -0700)

are available in the Git repository at:

git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security.git next-lockdown

for you to fetch changes up to 45893a0abee6b5fd52994a3a1095735aeaec472b:

kexec: Fix file verification on S390 (2019-09-10 13:27:51 +0100)

----------------------------------------------------------------
Dave Young (1):
lockdown: Copy secure_boot flag in boot params across kexec reboot

David Howells (10):
lockdown: Enforce module signatures if the kernel is locked down
lockdown: Prohibit PCMCIA CIS storage when the kernel is locked down
lockdown: Lock down TIOCSSERIAL
lockdown: Lock down module params that specify hardware parameters (eg. ioport)
x86/mmiotrace: Lock down the testmmiotrace module
lockdown: Lock down /proc/kcore
lockdown: Lock down tracing and perf kprobes when in confidentiality mode
bpf: Restrict bpf when kernel lockdown is in confidentiality mode
lockdown: Lock down perf when in confidentiality mode
debugfs: Restrict debugfs when the kernel is locked down

Jiri Bohac (2):
kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE
kexec_file: Restrict at runtime if the kernel is locked down

Josh Boyer (2):
hibernate: Disable when the kernel is locked down
acpi: Ignore acpi_rsdp kernel param when the kernel has been locked down

Linn Crosetto (1):
acpi: Disable ACPI table override if the kernel is locked down

Matthew Garrett (15):
security: Support early LSMs
security: Add a "locked down" LSM hook
security: Add a static lockdown policy LSM
lockdown: Restrict /dev/{mem,kmem,port} when the kernel is locked down
kexec_load: Disable at runtime if the kernel is locked down
PCI: Lock down BAR access when the kernel is locked down
x86: Lock down IO port access when the kernel is locked down
x86/msr: Restrict MSR access when the kernel is locked down
ACPI: Limit access to custom_method when the kernel is locked down
kexec: Allow kexec_file() with appropriate IMA policy when locked down
tracefs: Restrict tracefs when the kernel is locked down
efi: Restrict efivar_ssdt_load when the kernel is locked down
lockdown: Print current->comm in restriction messages
security: constify some arrays in lockdown LSM
kexec: Fix file verification on S390

Documentation/admin-guide/kernel-parameters.txt | 9 ++
arch/arm64/Kconfig | 6 +-
arch/s390/Kconfig | 2 +-
arch/s390/configs/debug_defconfig | 2 +-
arch/s390/configs/defconfig | 2 +-
arch/s390/configs/performance_defconfig | 2 +-
arch/s390/kernel/kexec_elf.c | 4 +-
arch/s390/kernel/kexec_image.c | 4 +-
arch/s390/kernel/machine_kexec_file.c | 4 +-
arch/x86/Kconfig | 20 ++-
arch/x86/boot/compressed/acpi.c | 19 ++-
arch/x86/include/asm/acpi.h | 9 ++
arch/x86/include/asm/x86_init.h | 2 +
arch/x86/kernel/acpi/boot.c | 5 +
arch/x86/kernel/ima_arch.c | 4 +-
arch/x86/kernel/ioport.c | 7 +-
arch/x86/kernel/kexec-bzimage64.c | 1 +
arch/x86/kernel/msr.c | 8 +
arch/x86/kernel/x86_init.c | 1 +
arch/x86/mm/testmmiotrace.c | 5 +
crypto/asymmetric_keys/verify_pefile.c | 4 +-
drivers/acpi/custom_method.c | 6 +
drivers/acpi/osl.c | 14 +-
drivers/acpi/tables.c | 6 +
drivers/char/mem.c | 7 +-
drivers/firmware/efi/efi.c | 6 +
drivers/pci/pci-sysfs.c | 16 ++
drivers/pci/proc.c | 14 +-
drivers/pci/syscall.c | 4 +-
drivers/pcmcia/cistpl.c | 5 +
drivers/tty/serial/serial_core.c | 5 +
fs/debugfs/file.c | 30 ++++
fs/debugfs/inode.c | 32 +++-
fs/proc/kcore.c | 6 +
fs/tracefs/inode.c | 42 +++++-
include/asm-generic/vmlinux.lds.h | 8 +-
include/linux/acpi.h | 6 +
include/linux/ima.h | 9 ++
include/linux/kexec.h | 4 +-
include/linux/lsm_hooks.h | 13 ++
include/linux/security.h | 59 ++++++++
init/Kconfig | 5 +
init/main.c | 1 +
kernel/events/core.c | 7 +
kernel/kexec.c | 8 +
kernel/kexec_file.c | 68 +++++++--
kernel/module.c | 37 ++++-
kernel/params.c | 21 ++-
kernel/power/hibernate.c | 3 +-
kernel/trace/bpf_trace.c | 10 ++
kernel/trace/trace_kprobe.c | 5 +
security/Kconfig | 11 +-
security/Makefile | 2 +
security/integrity/ima/Kconfig | 2 +-
security/integrity/ima/ima.h | 2 +
security/integrity/ima/ima_main.c | 4 +-
security/integrity/ima/ima_policy.c | 50 +++++++
security/lockdown/Kconfig | 47 ++++++
security/lockdown/Makefile | 1 +
security/lockdown/lockdown.c | 191 ++++++++++++++++++++++++
security/security.c | 56 ++++++-
61 files changed, 864 insertions(+), 79 deletions(-)
create mode 100644 security/lockdown/Kconfig
create mode 100644 security/lockdown/Makefile
create mode 100644 security/lockdown/lockdown.c