efi: Make efivarfs entries immutable by default

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / drivers / firmware / efi / vars.c

diff --git a/drivers/firmware/efi/vars.c b/drivers/firmware/efi/vars.c
index 05f4dc3cdb466a13c47562726c5790499747a0c2..37ed20efd5487b61da4d6b0075c888ec325abaf7 100644 (file)
--- a/drivers/firmware/efi/vars.c
+++ b/drivers/firmware/efi/vars.c
@@ -172,10 +172,12 @@ struct variable_validate {
 };
 
 /*
- * This is the list of variables we need to validate.
+ * This is the list of variables we need to validate, as well as the
+ * whitelist for what we think is safe not to default to immutable.
  *
  * If it has a validate() method that's not NULL, it'll go into the
- * validation routine.  If not, it is assumed valid.
+ * validation routine.  If not, it is assumed valid, but still used for
+ * whitelisting.
  *
  * Note that it's sorted by {vendor,name}, but globbed names must come after
  * any other name with the same prefix.
@@ -193,11 +195,37 @@ static const struct variable_validate variable_validate[] = {
        { EFI_GLOBAL_VARIABLE_GUID, "ErrOut", validate_device_path },
        { EFI_GLOBAL_VARIABLE_GUID, "ErrOutDev", validate_device_path },
        { EFI_GLOBAL_VARIABLE_GUID, "Lang", validate_ascii_string },
+       { EFI_GLOBAL_VARIABLE_GUID, "OsIndications", NULL },
        { EFI_GLOBAL_VARIABLE_GUID, "PlatformLang", validate_ascii_string },
        { EFI_GLOBAL_VARIABLE_GUID, "Timeout", validate_uint16 },
        { NULL_GUID, "", NULL },
 };
 
+static bool
+variable_matches(const char *var_name, size_t len, const char *match_name,
+                int *match)
+{
+       for (*match = 0; ; (*match)++) {
+               char c = match_name[*match];
+               char u = var_name[*match];
+
+               /* Wildcard in the matching name means we've matched */
+               if (c == '*')
+                       return true;
+
+               /* Case sensitive match */
+               if (!c && *match == len)
+                       return true;
+
+               if (c != u)
+                       return false;
+
+               if (!c)
+                       return true;
+       }
+       return true;
+}
+
 bool
 efivar_validate(efi_guid_t vendor, efi_char16_t *var_name, u8 *data,
                unsigned long data_size)
@@ -221,35 +249,48 @@ efivar_validate(efi_guid_t vendor, efi_char16_t *var_name, u8 *data,
                if (efi_guidcmp(vendor, variable_validate[i].vendor))
                        continue;
 
-               for (match = 0; ; match++) {
-                       char c = name[match];
-                       char u = utf8_name[match];
-
-                       /* Wildcard in the matching name means we've matched */
-                       if (c == '*') {
-                               kfree(utf8_name);
-                               return variable_validate[i].validate(var_name,
-                                                       match, data, data_size);
-                       }
-
-                       /* Case sensitive match */
-                       if (c != u)
+               if (variable_matches(utf8_name, utf8_size+1, name, &match)) {
+                       if (variable_validate[i].validate == NULL)
                                break;
-
-                       /* Reached the end of the string while matching */
-                       if (!c) {
-                               kfree(utf8_name);
-                               return variable_validate[i].validate(var_name,
-                                                       match, data, data_size);
-                       }
+                       kfree(utf8_name);
+                       return variable_validate[i].validate(var_name, match,
+                                                            data, data_size);
                }
        }
-
        kfree(utf8_name);
        return true;
 }
 EXPORT_SYMBOL_GPL(efivar_validate);
 
+bool
+efivar_variable_is_removable(efi_guid_t vendor, const char *var_name,
+                            size_t len)
+{
+       int i;
+       bool found = false;
+       int match = 0;
+
+       /*
+        * Check if our variable is in the validated variables list
+        */
+       for (i = 0; variable_validate[i].name[0] != '\0'; i++) {
+               if (efi_guidcmp(variable_validate[i].vendor, vendor))
+                       continue;
+
+               if (variable_matches(var_name, len,
+                                    variable_validate[i].name, &match)) {
+                       found = true;
+                       break;
+               }
+       }
+
+       /*
+        * If it's in our list, it is removable.
+        */
+       return found;
+}
+EXPORT_SYMBOL_GPL(efivar_variable_is_removable);
+
 static efi_status_t
 check_var_size(u32 attributes, unsigned long size)
 {