svn commit: r322278 - in head/sys: amd64/amd64 amd64/include dev/efidev

[Warner Losh]

Author: imp
Date: Tue Aug  8 20:44:16 2017
New Revision: 322278
URL: https://svnweb.freebsd.org/changeset/base/322278

Log:
  Fail to open efirt device when no EFI on system.
  
  libefivar expects opening /dev/efi to indicate if the we can make efi
  runtime calls. With a null routine, it was always succeeding leading
  efi_variables_supported() to return the wrong value. Only succeed if
  we have an efi_runtime table. Also, while I'm hear, out of an
  abundance of caution, add a likely redundant check to make sure
  efi_systbl is not NULL before dereferencing it. I know it can't be
  NULL if efi_cfgtbl is non-NULL, but the compiler doesn't.

Modified:
  head/sys/amd64/amd64/efirt.c
  head/sys/amd64/include/efi.h
  head/sys/dev/efidev/efidev.c

Modified: head/sys/amd64/amd64/efirt.c
==============================================================================
--- head/sys/amd64/amd64/efirt.c	Tue Aug  8 20:17:07 2017	(r322277)
+++ head/sys/amd64/amd64/efirt.c	Tue Aug  8 20:44:16 2017	(r322278)
@@ -421,12 +421,21 @@ efi_uninit(void)
 }
 
 int
+efi_rt_ok(void)
+{
+
+	if (efi_runtime == NULL)
+		return (ENXIO);
+	return (0);
+}
+
+int
 efi_get_table(struct uuid *uuid, void **ptr)
 {
 	struct efi_cfgtbl *ct;
 	u_long count;
 
-	if (efi_cfgtbl == NULL)
+	if (efi_cfgtbl == NULL || efi_systbl == NULL)
 		return (ENXIO);
 	count = efi_systbl->st_entries;
 	ct = efi_cfgtbl;

Modified: head/sys/amd64/include/efi.h
==============================================================================
--- head/sys/amd64/include/efi.h	Tue Aug  8 20:17:07 2017	(r322277)
+++ head/sys/amd64/include/efi.h	Tue Aug  8 20:44:16 2017	(r322278)
@@ -49,6 +49,7 @@
 struct uuid;
 struct efi_tm;
 
+int efi_rt_ok(void);
 int efi_get_table(struct uuid *uuid, void **ptr);
 int efi_get_time(struct efi_tm *tm);
 int efi_get_time_locked(struct efi_tm *tm);

Modified: head/sys/dev/efidev/efidev.c
==============================================================================
--- head/sys/dev/efidev/efidev.c	Tue Aug  8 20:17:07 2017	(r322277)
+++ head/sys/dev/efidev/efidev.c	Tue Aug  8 20:44:16 2017	(r322278)
@@ -39,14 +39,27 @@ __FBSDID("$FreeBSD$");
 #include <machine/efi.h>
 #include <sys/efiio.h>
 
+static d_open_t efidev_open;
 static d_ioctl_t efidev_ioctl;
 
 static struct cdevsw efi_cdevsw = {
 	.d_name = "efi",
 	.d_version = D_VERSION,
+	.d_open = efidev_open,
 	.d_ioctl = efidev_ioctl,
 };
 	
+static int
+efidev_open(struct cdev *dev __unused, int oflags __unused,
+    int devtype __unused, struct thread *td __unused)
+{
+	/*
+	 * Only return success when we have an actual runtime to call.
+	 */
+
+	return efi_rt_ok();
+}
+
 static int
 efidev_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t addr,
     int flags __unused, struct thread *td __unused)