Merge tag 'hwparam-20170420' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

Pull hw lockdown support from David Howells:
 "Annotation of module parameters that configure hardware resources
  including ioports, iomem addresses, irq lines and dma channels.

  This allows a future patch to prohibit the use of such module
  parameters to prevent that hardware from being abused to gain access
  to the running kernel image as part of locking the kernel down under
  UEFI secure boot conditions.

  Annotations are made by changing:

        module_param(n, t, p)
        module_param_named(n, v, t, p)
        module_param_array(n, t, m, p)

  to:

        module_param_hw(n, t, hwtype, p)
        module_param_hw_named(n, v, t, hwtype, p)
        module_param_hw_array(n, t, hwtype, m, p)

  where the module parameter refers to a hardware setting

  hwtype specifies the type of the resource being configured. This can
  be one of:

        ioport          Module parameter configures an I/O port
        iomem           Module parameter configures an I/O mem address
        ioport_or_iomem Module parameter could be either (runtime set)
        irq             Module parameter configures an I/O port
        dma             Module parameter configures a DMA channel
        dma_addr        Module parameter configures a DMA buffer address
        other           Module parameter configures some other value

  Note that the hwtype is compile checked, but not currently stored (the
  lockdown code probably won't require it). It is, however, there for
  future use.

  A bonus is that the hwtype can also be used for grepping.

  The intention is for the kernel to ignore or reject attempts to set
  annotated module parameters if lockdown is enabled. This applies to
  options passed on the boot command line, passed to insmod/modprobe or
  direct twiddling in /sys/module/ parameter files.

  The module initialisation then needs to handle the parameter not being
  set, by (1) giving an error, (2) probing for a value or (3) using a
  reasonable default.

  What I can't do is just reject a module out of hand because it may
  take a hardware setting in the module parameters. Some important
  modules, some ipmi stuff for instance, both probe for hardware and
  allow hardware to be manually specified; if the driver is aborts with
  any error, you don't get any ipmi hardware.

  Further, trying to do this entirely in the module initialisation code
  doesn't protect against sysfs twiddling.

  [!] Note that in and of itself, this series of patches should have no
      effect on the the size of the kernel or code execution - that is
      left to a patch in the next series to effect. It does mark
      annotated kernel parameters with a KERNEL_PARAM_FL_HWPARAM flag in
      an already existing field"

* tag 'hwparam-20170420' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs: (38 commits)
  Annotate hardware config module parameters in sound/pci/
  Annotate hardware config module parameters in sound/oss/
  Annotate hardware config module parameters in sound/isa/
  Annotate hardware config module parameters in sound/drivers/
  Annotate hardware config module parameters in fs/pstore/
  Annotate hardware config module parameters in drivers/watchdog/
  Annotate hardware config module parameters in drivers/video/
  Annotate hardware config module parameters in drivers/tty/
  Annotate hardware config module parameters in drivers/staging/vme/
  Annotate hardware config module parameters in drivers/staging/speakup/
  Annotate hardware config module parameters in drivers/staging/media/
  Annotate hardware config module parameters in drivers/scsi/
  Annotate hardware config module parameters in drivers/pcmcia/
  Annotate hardware config module parameters in drivers/pci/hotplug/
  Annotate hardware config module parameters in drivers/parport/
  Annotate hardware config module parameters in drivers/net/wireless/
  Annotate hardware config module parameters in drivers/net/wan/
  Annotate hardware config module parameters in drivers/net/irda/
  Annotate hardware config module parameters in drivers/net/hamradio/
  Annotate hardware config module parameters in drivers/net/ethernet/
  ...

1 files changed, 64 insertions, 1 deletions

diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
index 52666d90ca94..6be1949ebcdf 100644
--- a/include/linux/moduleparam.h
+++ b/include/linux/moduleparam.h
@@ -60,9 +60,11 @@ struct kernel_param_ops {
  * Flags available for kernel_param
  *
  * UNSAFE - the parameter is dangerous and setting it will taint the kernel
+ * HWPARAM - Hardware param not permitted in lockdown mode
  */
 enum {
-	KERNEL_PARAM_FL_UNSAFE = (1 << 0)
+	KERNEL_PARAM_FL_UNSAFE	= (1 << 0),
+	KERNEL_PARAM_FL_HWPARAM	= (1 << 1),
 };
 
 struct kernel_param {
@@ -451,6 +453,67 @@ extern int param_set_bint(const char *val, const struct kernel_param *kp);
 			    perm, -1, 0);				\
 	__MODULE_PARM_TYPE(name, "array of " #type)
 
+enum hwparam_type {
+	hwparam_ioport,		/* Module parameter configures an I/O port */
+	hwparam_iomem,		/* Module parameter configures an I/O mem address */
+	hwparam_ioport_or_iomem, /* Module parameter could be either, depending on other option */
+	hwparam_irq,		/* Module parameter configures an I/O port */
+	hwparam_dma,		/* Module parameter configures a DMA channel */
+	hwparam_dma_addr,	/* Module parameter configures a DMA buffer address */
+	hwparam_other,		/* Module parameter configures some other value */
+};
+
+/**
+ * module_param_hw_named - A parameter representing a hw parameters
+ * @name: a valid C identifier which is the parameter name.
+ * @value: the actual lvalue to alter.
+ * @type: the type of the parameter
+ * @hwtype: what the value represents (enum hwparam_type)
+ * @perm: visibility in sysfs.
+ *
+ * Usually it's a good idea to have variable names and user-exposed names the
+ * same, but that's harder if the variable must be non-static or is inside a
+ * structure.  This allows exposure under a different name.
+ */
+#define module_param_hw_named(name, value, type, hwtype, perm)		\
+	param_check_##type(name, &(value));				\
+	__module_param_call(MODULE_PARAM_PREFIX, name,			\
+			    &param_ops_##type, &value,			\
+			    perm, -1,					\
+			    KERNEL_PARAM_FL_HWPARAM | (hwparam_##hwtype & 0));	\
+	__MODULE_PARM_TYPE(name, #type)
+
+#define module_param_hw(name, type, hwtype, perm)		\
+	module_param_hw_named(name, name, type, hwtype, perm)
+
+/**
+ * module_param_hw_array - A parameter representing an array of hw parameters
+ * @name: the name of the array variable
+ * @type: the type, as per module_param()
+ * @hwtype: what the value represents (enum hwparam_type)
+ * @nump: optional pointer filled in with the number written
+ * @perm: visibility in sysfs
+ *
+ * Input and output are as comma-separated values.  Commas inside values
+ * don't work properly (eg. an array of charp).
+ *
+ * ARRAY_SIZE(@name) is used to determine the number of elements in the
+ * array, so the definition must be visible.
+ */
+#define module_param_hw_array(name, type, hwtype, nump, perm)		\
+	param_check_##type(name, &(name)[0]);				\
+	static const struct kparam_array __param_arr_##name		\
+	= { .max = ARRAY_SIZE(name), .num = nump,			\
+	    .ops = &param_ops_##type,					\
+	    .elemsize = sizeof(name[0]), .elem = name };		\
+	__module_param_call(MODULE_PARAM_PREFIX, name,			\
+			    &param_array_ops,				\
+			    .arr = &__param_arr_##name,			\
+			    perm, -1,					\
+			    KERNEL_PARAM_FL_HWPARAM | (hwparam_##hwtype & 0));	\
+	__MODULE_PARM_TYPE(name, "array of " #type)
+
+
 extern const struct kernel_param_ops param_array_ops;
 
 extern const struct kernel_param_ops param_ops_string;