diff options
| author |   Matthew Garrett <mjg59@srcf.ucam.org> | 2019-08-19 17:17:50 -0700 |
|---|---|---|
| committer |   James Morris <jmorris@namei.org> | 2019-08-19 21:54:16 -0700 |
| commit | f474e1486b78ac15322f8a1cda48a32a1deff9d3 (patch) | |
| tree | fe775561f6ce6e2a47ec9b837d398e5ab987efdd | |
| parent | x86/msr: Restrict MSR access when the kernel is locked down (diff) | |
| download | linux-dev-f474e1486b78ac15322f8a1cda48a32a1deff9d3.tar.xz linux-dev-f474e1486b78ac15322f8a1cda48a32a1deff9d3.zip | |
ACPI: Limit access to custom_method when the kernel is locked down
custom_method effectively allows arbitrary access to system memory, making
it possible for an attacker to circumvent restrictions on module loading.
Disable it if the kernel is locked down.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
cc: linux-acpi@vger.kernel.org
Signed-off-by: James Morris <jmorris@namei.org>
| -rw-r--r-- | drivers/acpi/custom_method.c | 6 | ||||
| -rw-r--r-- | include/linux/security.h | 1 | ||||
| -rw-r--r-- | security/lockdown/lockdown.c | 1 |
3 files changed, 8 insertions, 0 deletions
diff --git a/drivers/acpi/custom_method.c b/drivers/acpi/custom_method.c index b2ef4c2ec955..7031307becd7 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/include/linux/security.h b/include/linux/security.h index 010637a79eac..390e39395112 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -110,6 +110,7 @@ enum lockdown_reason { LOCKDOWN_PCI_ACCESS, LOCKDOWN_IOPORT, LOCKDOWN_MSR, + LOCKDOWN_ACPI_TABLES, LOCKDOWN_INTEGRITY_MAX, LOCKDOWN_CONFIDENTIALITY_MAX, }; diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c index b1c1c72440d5..6d44db0ddffa 100644 --- a/security/lockdown/lockdown.c +++ b/security/lockdown/lockdown.c @@ -25,6 +25,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = { [LOCKDOWN_PCI_ACCESS] = "direct PCI access", [LOCKDOWN_IOPORT] = "raw io port access", [LOCKDOWN_MSR] = "raw MSR access", + [LOCKDOWN_ACPI_TABLES] = "modifying ACPI tables", [LOCKDOWN_INTEGRITY_MAX] = "integrity", [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality", }; |