commit 4971c268b85e1c7a734a61622fc0813c86e2362e upstream.
Commit 98de59bfe4 ("take calculation of final prot in
security_mmap_file() into a helper") moved the code to update prot, to be
the actual protections applied to the kernel, to a new helper called
mmap_prot().
However, while without the helper ima_file_mmap() was getting the updated
prot, with the helper ima_file_mmap() gets the original prot, which
contains the protections requested by the application.
A possible consequence of this change is that, if an application calls
mmap() with only PROT_READ, and the kernel applies PROT_EXEC in addition,
that application would have access to executable memory without having this
event recorded in the IMA measurement list. This situation would occur for
example if the application, before mmap(), calls the personality() system
call with READ_IMPLIES_EXEC as the first argument.
Align ima_file_mmap() parameters with those of the mmap_file LSM hook, so
that IMA can receive both the requested prot and the final prot. Since the
requested protections are stored in a new variable, and the final
protections are stored in the existing variable, this effectively restores
the original behavior of the MMAP_CHECK hook.
Cc: stable@vger.kernel.org
Fixes: 98de59bfe4 ("take calculation of final prot in security_mmap_file() into a helper")
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
As with the kernel_load_data LSM hook, add a "contents" flag to the
kernel_read_file LSM hook that indicates whether the LSM can expect
a matching call to the kernel_post_read_file LSM hook with the full
contents of the file. With the coming addition of partial file read
support for kernel_read_file*() API, the LSM will no longer be able
to always see the entire contents of a file during the read calls.
For cases where the LSM must read examine the complete file contents,
it will need to do so on its own every time the kernel_read_file
hook is called with contents=false (or reject such cases). Adjust all
existing LSMs to retain existing behavior.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Link: https://lore.kernel.org/r/20201002173828.2099543-12-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There are a few places in the kernel where LSMs would like to have
visibility into the contents of a kernel buffer that has been loaded or
read. While security_kernel_post_read_file() (which includes the
buffer) exists as a pairing for security_kernel_read_file(), no such
hook exists to pair with security_kernel_load_data().
Earlier proposals for just using security_kernel_post_read_file() with a
NULL file argument were rejected (i.e. "file" should always be valid for
the security_..._file hooks, but it appears at least one case was
left in the kernel during earlier refactoring. (This will be fixed in
a subsequent patch.)
Since not all cases of security_kernel_load_data() can have a single
contiguous buffer made available to the LSM hook (e.g. kexec image
segments are separately loaded), there needs to be a way for the LSM to
reason about its expectations of the hook coverage. In order to handle
this, add a "contents" argument to the "kernel_load_data" hook that
indicates if the newly added "kernel_post_load_data" hook will be called
with the full contents once loaded. That way, LSMs requiring full contents
can choose to unilaterally reject "kernel_load_data" with contents=false
(which is effectively the existing hook coverage), but when contents=true
they can allow it and later evaluate the "kernel_post_load_data" hook
once the buffer is loaded.
With this change, LSMs can gain coverage over non-file-backed data loads
(e.g. init_module(2) and firmware userspace helper), which will happen
in subsequent patches.
Additionally prepare IMA to start processing these cases.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: KP Singh <kpsingh@google.com>
Link: https://lore.kernel.org/r/20201002173828.2099543-9-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Take the properties of the kexec kernel's inode and the current task
ownership into consideration when matching a KEXEC_CMDLINE operation to
the rules in the IMA policy. This allows for some uniformity when
writing IMA policy rules for KEXEC_KERNEL_CHECK, KEXEC_INITRAMFS_CHECK,
and KEXEC_CMDLINE operations.
Prior to this patch, it was not possible to write a set of rules like
this:
dont_measure func=KEXEC_KERNEL_CHECK obj_type=foo_t
dont_measure func=KEXEC_INITRAMFS_CHECK obj_type=foo_t
dont_measure func=KEXEC_CMDLINE obj_type=foo_t
measure func=KEXEC_KERNEL_CHECK
measure func=KEXEC_INITRAMFS_CHECK
measure func=KEXEC_CMDLINE
The inode information associated with the kernel being loaded by a
kexec_kernel_load(2) syscall can now be included in the decision to
measure or not
Additonally, the uid, euid, and subj_* conditionals can also now be
used in KEXEC_CMDLINE rules. There was no technical reason as to why
those conditionals weren't being considered previously other than
ima_match_rules() didn't have a valid inode to use so it immediately
bailed out for KEXEC_CMDLINE operations rather than going through the
full list of conditional comparisons.
Signed-off-by: Tyler Hicks <tyhicks@linux.microsoft.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: kexec@lists.infradead.org
Reviewed-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Files can be mmap'ed read/write and later changed to execute to circumvent
IMA's mmap appraise policy rules. Due to locking issues (mmap semaphore
would be taken prior to i_mutex), files can not be measured or appraised at
this point. Eliminate this integrity gap, by denying the mprotect
PROT_EXECUTE change, if an mmap appraise policy rule exists.
On mprotect change success, return 0. On failure, return -EACESS.
Reviewed-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Every time a new architecture defines the IMA architecture specific
functions - arch_ima_get_secureboot() and arch_ima_get_policy(), the IMA
include file needs to be updated. To avoid this "noise", this patch
defines a new IMA Kconfig IMA_SECURE_AND_OR_TRUSTED_BOOT option, allowing
the different architectures to select it.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Philipp Rudo <prudo@linux.ibm.com> (s390)
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
This allows other parts of the kernel (perhaps a stacked LSM allowing
system monitoring, eg. the proposed KRSI LSM [1]) to retrieve the hash
of a given file from IMA if it's present in the iint cache.
It's true that the existence of the hash means that it's also in the
audit logs or in /sys/kernel/security/ima/ascii_runtime_measurements,
but it can be difficult to pull that information out for every
subsequent exec. This is especially true if a given host has been up
for a long time and the file was first measured a long time ago.
It should be kept in mind that this function gives access to cached
entries which can be removed, for instance on security_inode_free().
This is based on Peter Moody's patch:
https://sourceforge.net/p/linux-ima/mailman/message/33036180/
[1] https://lkml.org/lkml/2019/9/10/393
Signed-off-by: Florent Revest <revest@google.com>
Reviewed-by: KP Singh <kpsingh@chromium.org>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
As a result of the asymmetric public keys subtype Kconfig option being
defined as tristate, with the existing IMA Makefile, ima_asymmetric_keys.c
could be built as a kernel module. To prevent this from happening, this
patch defines and uses an intermediate Kconfig boolean option named
IMA_MEASURE_ASYMMETRIC_KEYS.
Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Suggested-by: James.Bottomley <James.Bottomley@HansenPartnership.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reported-by: kbuild test robot <lkp@intel.com> # ima_asymmetric_keys.c
is built as a kernel module.
Fixes: 88e70da170 ("IMA: Define an IMA hook to measure keys")
Fixes: cb1aa3823c ("KEYS: Call the IMA hook to measure keys")
[zohar@linux.ibm.com: updated patch description]
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Call the IMA hook from key_create_or_update() function to measure
the payload when a new key is created or an existing key is updated.
This patch adds the call to the IMA hook from key_create_or_update()
function to measure the key on key create or update.
Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
PowerNV systems use a Linux-based bootloader, which rely on the IMA
subsystem to enforce different secure boot modes. Since the
verification policy may differ based on the secure boot mode of the
system, the policies must be defined at runtime.
This patch implements arch-specific support to define IMA policy rules
based on the runtime secure boot mode of the system.
This patch provides arch-specific IMA policies if PPC_SECURE_BOOT
config is enabled.
Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1572492694-6520-3-git-send-email-zohar@linux.ibm.com
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
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 9d1f8be5cf ("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
...
Systems in lockdown mode should block the kexec of untrusted kernels.
For x86 and ARM we can ensure that a kernel is trustworthy by validating
a PE signature, but this isn't possible on other architectures. On those
platforms we can use IMA digital signatures instead. Add a function to
determine whether IMA has or will verify signatures for a given event type,
and if so permit kexec_file() even if the kernel is otherwise locked down.
This is restricted to cases where CONFIG_INTEGRITY_TRUSTED_KEYRING is set
in order to prevent an attacker from loading additional keys at runtime.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Acked-by: Mimi Zohar <zohar@linux.ibm.com>
Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
Cc: linux-integrity@vger.kernel.org
Signed-off-by: James Morris <jmorris@namei.org>
Pull integrity updates from Mimi Zohar:
"Bug fixes, code clean up, and new features:
- IMA policy rules can be defined in terms of LSM labels, making the
IMA policy dependent on LSM policy label changes, in particular LSM
label deletions. The new environment, in which IMA-appraisal is
being used, frequently updates the LSM policy and permits LSM label
deletions.
- Prevent an mmap'ed shared file opened for write from also being
mmap'ed execute. In the long term, making this and other similar
changes at the VFS layer would be preferable.
- The IMA per policy rule template format support is needed for a
couple of new/proposed features (eg. kexec boot command line
measurement, appended signatures, and VFS provided file hashes).
- Other than the "boot-aggregate" record in the IMA measuremeent
list, all other measurements are of file data. Measuring and
storing the kexec boot command line in the IMA measurement list is
the first buffer based measurement included in the measurement
list"
* 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity:
integrity: Introduce struct evm_xattr
ima: Update MAX_TEMPLATE_NAME_LEN to fit largest reasonable definition
KEXEC: Call ima_kexec_cmdline to measure the boot command line args
IMA: Define a new template field buf
IMA: Define a new hook to measure the kexec boot command line arguments
IMA: support for per policy rule template formats
integrity: Fix __integrity_init_keyring() section mismatch
ima: Use designated initializers for struct ima_event_data
ima: use the lsm policy update notifier
LSM: switch to blocking policy update notifiers
x86/ima: fix the Kconfig dependency for IMA_ARCH_POLICY
ima: Make arch_policy_entry static
ima: prevent a file already mmap'ed write to be mmap'ed execute
x86/ima: check EFI SetupMode too
Currently during soft reboot(kexec_file_load) boot command line
arguments are not measured. Define hooks needed to measure kexec
command line arguments during soft reboot(kexec_file_load).
- A new ima hook ima_kexec_cmdline is defined to be called by the
kexec code.
- A new function process_buffer_measurement is defined to measure
the buffer hash into the IMA measurement list.
- A new func policy KEXEC_CMDLINE is defined to control the
measurement.
Signed-off-by: Prakhar Srivastava <prsriva02@gmail.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation version 2 of the license
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 315 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Armijn Hemel <armijn@tjaldur.nl>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190531190115.503150771@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
A kernel loaded via kexec_load cannot be verified. Thus disable kexec_load
systemcall in kernels which where IPLed securely. Use the IMA mechanism to
do so.
Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
If tmpfiles can be made persistent, then newly created tmpfiles need to
be treated like any other new files in policy.
This patch indicates which newly created tmpfiles are in policy, causing
the file hash to be calculated on __fput().
Reported-by: Ignaz Forster <ignaz.forster@gmx.de>
[rgoldwyn@suse.com: Call ima_post_create_tmpfile() in vfs_tmpfile() as
opposed to do_tmpfile(). This will help the case for overlayfs where
copy_up is denied while overwriting a file.]
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
The secure boot mode may not be detected on boot for some reason (eg.
buggy firmware). This patch attempts one more time to detect the
secure boot mode.
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
On x86, there are two methods of verifying a kexec'ed kernel image
signature being loaded via the kexec_file_load syscall - an architecture
specific implementaton or a IMA KEXEC_KERNEL_CHECK appraisal rule. Neither
of these methods verify the kexec'ed kernel image signature being loaded
via the kexec_load syscall.
Secure boot enabled systems require kexec images to be signed. Therefore,
this patch loads an IMA KEXEC_KERNEL_CHECK policy rule on secure boot
enabled systems not configured with CONFIG_KEXEC_VERIFY_SIG enabled.
When IMA_APPRAISE_BOOTPARAM is configured, different IMA appraise modes
(eg. fix, log) can be specified on the boot command line, allowing unsigned
or invalidly signed kernel images to be kexec'ed. This patch permits
enabling IMA_APPRAISE_BOOTPARAM or IMA_ARCH_POLICY, but not both.
Signed-off-by: Eric Richter <erichte@linux.ibm.com>
Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Peter Jones <pjones@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Builtin IMA policies can be enabled on the boot command line, and replaced
with a custom policy, normally during early boot in the initramfs. Build
time IMA policy rules were recently added. These rules are automatically
enabled on boot and persist after loading a custom policy.
There is a need for yet another type of policy, an architecture specific
policy, which is derived at runtime during kernel boot, based on the
runtime secure boot flags. Like the build time policy rules, these rules
persist after loading a custom policy.
This patch adds support for loading an architecture specific IMA policy.
Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
Co-Developed-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Distros are concerned about totally disabling the kexec_load syscall.
As a compromise, the kexec_load syscall will only be disabled when
CONFIG_KEXEC_VERIFY_SIG is configured and the system is booted with
secureboot enabled.
This patch defines the new arch specific function called
arch_ima_get_secureboot() to retrieve the secureboot state of the system.
Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
Suggested-by: Seth Forshee <seth.forshee@canonical.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Peter Jones <pjones@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Pull security subsystem updates from James Morris:
- kstrdup() return value fix from Eric Biggers
- Add new security_load_data hook to differentiate security checking of
kernel-loaded binaries in the case of there being no associated file
descriptor, from Mimi Zohar.
- Add ability to IMA to specify a policy at build-time, rather than
just via command line params or by loading a custom policy, from
Mimi.
- Allow IMA and LSMs to prevent sysfs firmware load fallback (e.g. if
using signed firmware), from Mimi.
- Allow IMA to deny loading of kexec kernel images, as they cannot be
measured by IMA, from Mimi.
* 'next-general' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
security: check for kstrdup() failure in lsm_append()
security: export security_kernel_load_data function
ima: based on policy warn about loading firmware (pre-allocated buffer)
module: replace the existing LSM hook in init_module
ima: add build time policy
ima: based on policy require signed firmware (sysfs fallback)
firmware: add call to LSM hook before firmware sysfs fallback
ima: based on policy require signed kexec kernel images
kexec: add call to LSM hook in original kexec_load syscall
security: define new LSM hook named security_kernel_load_data
MAINTAINERS: remove the outdated "LINUX SECURITY MODULE (LSM) FRAMEWORK" entry
