efivarfs: Fix error on non-existent file

When looking up a non-existent file, efivarfs returns -EINVAL if the
file does not conform to the NAME-GUID format and -ENOENT if it does.
This is caused by efivars_d_hash() returning -EINVAL if the name is not
formatted correctly.  This error is returned before simple_lookup()
returns a negative dentry, and is the error value that the user sees.

Fix by removing this check.  If the file does not exist, simple_lookup()
will return a negative dentry leading to -ENOENT and efivarfs_create()
already has a validity check before it creates an entry (and will
correctly return -EINVAL)

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: <stable@vger.kernel.org>
[ardb: make efivarfs_valid_name() static]
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

Author: jejb

fs/efivarfs/inode.c

@@ -51,7 +51,7 @@ struct inode *efivarfs_get_inode(struct super_block *sb,
  *
  *	VariableName-12345678-1234-1234-1234-1234567891bc
  */
-bool efivarfs_valid_name(const char *str, int len)
+static bool efivarfs_valid_name(const char *str, int len)
 {
 	const char *s = str + len - EFI_VARIABLE_GUID_LEN;
 

fs/efivarfs/internal.h

@@ -60,7 +60,6 @@ bool efivar_variable_is_removable(efi_guid_t vendor, const char *name,
 
 extern const struct file_operations efivarfs_file_operations;
 extern const struct inode_operations efivarfs_dir_inode_operations;
-extern bool efivarfs_valid_name(const char *str, int len);
 extern struct inode *efivarfs_get_inode(struct super_block *sb,
 			const struct inode *dir, int mode, dev_t dev,
 			bool is_removable);

fs/efivarfs/super.c

@@ -144,9 +144,6 @@ static int efivarfs_d_hash(const struct dentry *dentry, struct qstr *qstr)
 	const unsigned char *s = qstr->name;
 	unsigned int len = qstr->len;
 
-	if (!efivarfs_valid_name(s, len))
-		return -EINVAL;
-
 	while (len-- > EFI_VARIABLE_GUID_LEN)
 		hash = partial_name_hash(*s++, hash);