fscrypt: move fscrypt_d_revalidate() to fname.c

fscrypt_d_revalidate() and fscrypt_d_ops really belong in fname.c, since
they're specific to filenames encryption.  crypto.c is for contents
encryption and general fs/crypto/ initialization and utilities.

Link: https://lore.kernel.org/r/20191209204359.228544-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>

fs/crypto/crypto.c

@@ -24,8 +24,6 @@
 #include <linux/module.h>
 #include <linux/scatterlist.h>
 #include <linux/ratelimit.h>
-#include <linux/dcache.h>
-#include <linux/namei.h>
 #include <crypto/skcipher.h>
 #include "fscrypt_private.h"
 
@@ -285,54 +283,6 @@ int fscrypt_decrypt_block_inplace(const struct inode *inode, struct page *page,
 }
 EXPORT_SYMBOL(fscrypt_decrypt_block_inplace);
 
-/*
- * Validate dentries in encrypted directories to make sure we aren't potentially
- * caching stale dentries after a key has been added.
- */
-static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags)
-{
-	struct dentry *dir;
-	int err;
-	int valid;
-
-	/*
-	 * Plaintext names are always valid, since fscrypt doesn't support
-	 * reverting to ciphertext names without evicting the directory's inode
-	 * -- which implies eviction of the dentries in the directory.
-	 */
-	if (!(dentry->d_flags & DCACHE_ENCRYPTED_NAME))
-		return 1;
-
-	/*
-	 * Ciphertext name; valid if the directory's key is still unavailable.
-	 *
-	 * Although fscrypt forbids rename() on ciphertext names, we still must
-	 * use dget_parent() here rather than use ->d_parent directly.  That's
-	 * because a corrupted fs image may contain directory hard links, which
-	 * the VFS handles by moving the directory's dentry tree in the dcache
-	 * each time ->lookup() finds the directory and it already has a dentry
-	 * elsewhere.  Thus ->d_parent can be changing, and we must safely grab
-	 * a reference to some ->d_parent to prevent it from being freed.
-	 */
-
-	if (flags & LOOKUP_RCU)
-		return -ECHILD;
-
-	dir = dget_parent(dentry);
-	err = fscrypt_get_encryption_info(d_inode(dir));
-	valid = !fscrypt_has_encryption_key(d_inode(dir));
-	dput(dir);
-
-	if (err < 0)
-		return err;
-
-	return valid;
-}
-
-const struct dentry_operations fscrypt_d_ops = {
-	.d_revalidate = fscrypt_d_revalidate,
-};
-
 /**
  * fscrypt_initialize() - allocate major buffers for fs encryption.
  * @cop_flags:  fscrypt operations flags

fs/crypto/fname.c

@@ -11,6 +11,7 @@
  * This has not yet undergone a rigorous security audit.
  */
 
+#include <linux/namei.h>
 #include <linux/scatterlist.h>
 #include <crypto/skcipher.h>
 #include "fscrypt_private.h"
@@ -400,3 +401,51 @@ int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname,
 	return ret;
 }
 EXPORT_SYMBOL(fscrypt_setup_filename);
+
+/*
+ * Validate dentries in encrypted directories to make sure we aren't potentially
+ * caching stale dentries after a key has been added.
+ */
+static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags)
+{
+	struct dentry *dir;
+	int err;
+	int valid;
+
+	/*
+	 * Plaintext names are always valid, since fscrypt doesn't support
+	 * reverting to ciphertext names without evicting the directory's inode
+	 * -- which implies eviction of the dentries in the directory.
+	 */
+	if (!(dentry->d_flags & DCACHE_ENCRYPTED_NAME))
+		return 1;
+
+	/*
+	 * Ciphertext name; valid if the directory's key is still unavailable.
+	 *
+	 * Although fscrypt forbids rename() on ciphertext names, we still must
+	 * use dget_parent() here rather than use ->d_parent directly.  That's
+	 * because a corrupted fs image may contain directory hard links, which
+	 * the VFS handles by moving the directory's dentry tree in the dcache
+	 * each time ->lookup() finds the directory and it already has a dentry
+	 * elsewhere.  Thus ->d_parent can be changing, and we must safely grab
+	 * a reference to some ->d_parent to prevent it from being freed.
+	 */
+
+	if (flags & LOOKUP_RCU)
+		return -ECHILD;
+
+	dir = dget_parent(dentry);
+	err = fscrypt_get_encryption_info(d_inode(dir));
+	valid = !fscrypt_has_encryption_key(d_inode(dir));
+	dput(dir);
+
+	if (err < 0)
+		return err;
+
+	return valid;
+}
+
+const struct dentry_operations fscrypt_d_ops = {
+	.d_revalidate = fscrypt_d_revalidate,
+};

fs/crypto/fscrypt_private.h

@@ -233,7 +233,6 @@ extern int fscrypt_crypt_block(const struct inode *inode,
 			       unsigned int len, unsigned int offs,
 			       gfp_t gfp_flags);
 extern struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags);
-extern const struct dentry_operations fscrypt_d_ops;
 
 extern void __printf(3, 4) __cold
 fscrypt_msg(const struct inode *inode, const char *level, const char *fmt, ...);
@@ -265,6 +264,7 @@ extern int fname_encrypt(const struct inode *inode, const struct qstr *iname,
 extern bool fscrypt_fname_encrypted_size(const struct inode *inode,
 					 u32 orig_len, u32 max_len,
 					 u32 *encrypted_len_ret);
+extern const struct dentry_operations fscrypt_d_ops;
 
 /* hkdf.c */