diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2019-09-28 08:14:15 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-09-28 08:14:15 -0700 |
commit | aefcf2f4b58155d27340ba5f9ddbe9513da8286d (patch) | |
tree | a8ae994ca71b2e43e3075c796165e5ed62e28e42 /drivers/acpi | |
parent | f1f2f614d535564992f32e720739cb53cf03489f (diff) | |
parent | 45893a0abee6b5fd52994a3a1095735aeaec472b (diff) | |
download | linux-aefcf2f4b58155d27340ba5f9ddbe9513da8286d.tar.bz2 |
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
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"
* '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
...
Diffstat (limited to 'drivers/acpi')
-rw-r--r-- | drivers/acpi/custom_method.c | 6 | ||||
-rw-r--r-- | drivers/acpi/osl.c | 14 | ||||
-rw-r--r-- | drivers/acpi/tables.c | 6 |
3 files changed, 25 insertions, 1 deletions
diff --git a/drivers/acpi/custom_method.c b/drivers/acpi/custom_method.c index fd66a736621c..b097ef209313 100644 --- a/drivers/acpi/custom_method.c +++ b/drivers/acpi/custom_method.c @@ -9,6 +9,7 @@ #include <linux/uaccess.h> #include <linux/debugfs.h> #include <linux/acpi.h> +#include <linux/security.h> #include "internal.h" @@ -29,6 +30,11 @@ static ssize_t cm_write(struct file *file, const char __user * user_buf, struct acpi_table_header table; acpi_status status; + int ret; + + ret = security_locked_down(LOCKDOWN_ACPI_TABLES); + if (ret) + return ret; if (!(*ppos)) { /* parse the table header to get the table length */ diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c index 2f9d0d20b836..a2e844a8e9ed 100644 --- a/drivers/acpi/osl.c +++ b/drivers/acpi/osl.c @@ -27,6 +27,7 @@ #include <linux/list.h> #include <linux/jiffies.h> #include <linux/semaphore.h> +#include <linux/security.h> #include <asm/io.h> #include <linux/uaccess.h> @@ -182,8 +183,19 @@ acpi_physical_address __init acpi_os_get_root_pointer(void) acpi_physical_address pa; #ifdef CONFIG_KEXEC - if (acpi_rsdp) + /* + * We may have been provided with an RSDP on the command line, + * but if a malicious user has done so they may be pointing us + * at modified ACPI tables that could alter kernel behaviour - + * so, we check the lockdown status before making use of + * it. If we trust it then also stash it in an architecture + * specific location (if appropriate) so it can be carried + * over further kexec()s. + */ + if (acpi_rsdp && !security_locked_down(LOCKDOWN_ACPI_TABLES)) { + acpi_arch_set_root_pointer(acpi_rsdp); return acpi_rsdp; + } #endif pa = acpi_arch_get_root_pointer(); if (pa) diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c index b32327759380..180ac4329763 100644 --- a/drivers/acpi/tables.c +++ b/drivers/acpi/tables.c @@ -20,6 +20,7 @@ #include <linux/memblock.h> #include <linux/earlycpio.h> #include <linux/initrd.h> +#include <linux/security.h> #include "internal.h" #ifdef CONFIG_ACPI_CUSTOM_DSDT @@ -578,6 +579,11 @@ void __init acpi_table_upgrade(void) if (table_nr == 0) return; + if (security_locked_down(LOCKDOWN_ACPI_TABLES)) { + pr_notice("kernel is locked down, ignoring table override\n"); + return; + } + acpi_tables_addr = memblock_find_in_range(0, ACPI_TABLE_UPGRADE_MAX_PHYS, all_tables_size, PAGE_SIZE); |