Messages in this thread Patch in this message | | | Date | Tue, 26 Mar 2019 11:27:29 -0700 | Subject | [PATCH V31 13/25] ACPI: Limit access to custom_method when the kernel is locked down | From | Matthew Garrett <> |
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From: Matthew Garrett <mjg59@srcf.ucam.org>
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> cc: linux-acpi@vger.kernel.org --- drivers/acpi/custom_method.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/drivers/acpi/custom_method.c b/drivers/acpi/custom_method.c index 4451877f83b6..37de3cd84493 100644 --- a/drivers/acpi/custom_method.c +++ b/drivers/acpi/custom_method.c @@ -29,6 +29,9 @@ static ssize_t cm_write(struct file *file, const char __user * user_buf, struct acpi_table_header table; acpi_status status; + if (kernel_is_locked_down("ACPI custom methods", LOCKDOWN_INTEGRITY)) + return -EPERM; + if (!(*ppos)) { /* parse the table header to get the table length */ if (count <= sizeof(struct acpi_table_header)) -- 2.21.0.392.gf8f6787159e-goog
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