fscrypt: new helper function - fscrypt_prepare_lookup()

[mirror_ubuntu-bionic-kernel.git] / include / linux / fscrypt.h

diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index c422367baed925e9b706bba99f9d69abe5d909b1..2327859c8cd265c6b8c178343eaa788c19275c1b 100644 (file)
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -237,4 +237,32 @@ static inline int fscrypt_prepare_rename(struct inode *old_dir,
        return 0;
 }
 
+/**
+ * fscrypt_prepare_lookup - prepare to lookup a name in a possibly-encrypted directory
+ * @dir: directory being searched
+ * @dentry: filename being looked up
+ * @flags: lookup flags
+ *
+ * Prepare for ->lookup() in a directory which may be encrypted.  Lookups can be
+ * done with or without the directory's encryption key; without the key,
+ * filenames are presented in encrypted form.  Therefore, we'll try to set up
+ * the directory's encryption key, but even without it the lookup can continue.
+ *
+ * To allow invalidating stale dentries if the directory's encryption key is
+ * added later, we also install a custom ->d_revalidate() method and use the
+ * DCACHE_ENCRYPTED_WITH_KEY flag to indicate whether a given dentry is a
+ * plaintext name (flag set) or a ciphertext name (flag cleared).
+ *
+ * Return: 0 on success, -errno if a problem occurred while setting up the
+ * encryption key
+ */
+static inline int fscrypt_prepare_lookup(struct inode *dir,
+                                        struct dentry *dentry,
+                                        unsigned int flags)
+{
+       if (IS_ENCRYPTED(dir))
+               return __fscrypt_prepare_lookup(dir, dentry);
+       return 0;
+}
+
 #endif /* _LINUX_FSCRYPT_H */