eCryptfs: Filename Encryption: filldir, lookup, and readlink

Make the requisite modifications to ecryptfs_filldir(), ecryptfs_lookup(),
and ecryptfs_readlink() to call out to filename encryption functions.
Propagate filename encryption policy flags from mount-wide crypt_stat to
inode crypt_stat.
Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: Dustin Kirkland <dustin.kirkland@gmail.com>
Cc: Eric Sandeen <sandeen@redhat.com>
Cc: Tyler Hicks <tchicks@us.ibm.com>
Cc: David Kleikamp <shaggy@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ecryptfs/crypto.c

@@ -924,6 +924,15 @@ static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
 		crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
 	if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 		crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
+	if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
+		crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES;
+		if (mount_crypt_stat->flags
+		    & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)
+			crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK;
+		else if (mount_crypt_stat->flags
+			 & ECRYPTFS_GLOBAL_ENCFN_USE_FEK)
+			crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK;
+	}
 }
 
 static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
@@ -1060,7 +1069,8 @@ struct ecryptfs_flag_map_elem {
 static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
 	{0x00000001, ECRYPTFS_ENABLE_HMAC},
 	{0x00000002, ECRYPTFS_ENCRYPTED},
-	{0x00000004, ECRYPTFS_METADATA_IN_XATTR}
+	{0x00000004, ECRYPTFS_METADATA_IN_XATTR},
+	{0x00000008, ECRYPTFS_ENCRYPT_FILENAMES}
 };
 
 /**
@@ -1213,6 +1223,8 @@ int ecryptfs_read_and_validate_header_region(char *data,
 		&(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
 	int rc;
 
+	if (crypt_stat->extent_size == 0)
+		crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
 	rc = ecryptfs_read_lower(data, 0, crypt_stat->extent_size,
 				 ecryptfs_inode);
 	if (rc) {
@@ -1222,7 +1234,6 @@ int ecryptfs_read_and_validate_header_region(char *data,
 	}
 	if (!contains_ecryptfs_marker(data + ECRYPTFS_FILE_SIZE_BYTES)) {
 		rc = -EINVAL;
-		ecryptfs_printk(KERN_DEBUG, "Valid marker not found\n");
 	}
 out:
 	return rc;
@@ -1628,98 +1639,6 @@ int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
 	return rc;
 }
 
-/**
- * ecryptfs_encode_filename - converts a plaintext file name to cipher text
- * @crypt_stat: The crypt_stat struct associated with the file anem to encode
- * @name: The plaintext name
- * @length: The length of the plaintext
- * @encoded_name: The encypted name
- *
- * Encrypts and encodes a filename into something that constitutes a
- * valid filename for a filesystem, with printable characters.
- *
- * We assume that we have a properly initialized crypto context,
- * pointed to by crypt_stat->tfm.
- *
- * TODO: Implement filename decoding and decryption here, in place of
- * memcpy. We are keeping the framework around for now to (1)
- * facilitate testing of the components needed to implement filename
- * encryption and (2) to provide a code base from which other
- * developers in the community can easily implement this feature.
- *
- * Returns the length of encoded filename; negative if error
- */
-int
-ecryptfs_encode_filename(struct ecryptfs_crypt_stat *crypt_stat,
-			 const char *name, int length, char **encoded_name)
-{
-	int error = 0;
-
-	(*encoded_name) = kmalloc(length + 2, GFP_KERNEL);
-	if (!(*encoded_name)) {
-		error = -ENOMEM;
-		goto out;
-	}
-	/* TODO: Filename encryption is a scheduled feature for a
-	 * future version of eCryptfs. This function is here only for
-	 * the purpose of providing a framework for other developers
-	 * to easily implement filename encryption. Hint: Replace this
-	 * memcpy() with a call to encrypt and encode the
-	 * filename, the set the length accordingly. */
-	memcpy((void *)(*encoded_name), (void *)name, length);
-	(*encoded_name)[length] = '\0';
-	error = length + 1;
-out:
-	return error;
-}
-
-/**
- * ecryptfs_decode_filename - converts the cipher text name to plaintext
- * @crypt_stat: The crypt_stat struct associated with the file
- * @name: The filename in cipher text
- * @length: The length of the cipher text name
- * @decrypted_name: The plaintext name
- *
- * Decodes and decrypts the filename.
- *
- * We assume that we have a properly initialized crypto context,
- * pointed to by crypt_stat->tfm.
- *
- * TODO: Implement filename decoding and decryption here, in place of
- * memcpy. We are keeping the framework around for now to (1)
- * facilitate testing of the components needed to implement filename
- * encryption and (2) to provide a code base from which other
- * developers in the community can easily implement this feature.
- *
- * Returns the length of decoded filename; negative if error
- */
-int
-ecryptfs_decode_filename(struct ecryptfs_crypt_stat *crypt_stat,
-			 const char *name, int length, char **decrypted_name)
-{
-	int error = 0;
-
-	(*decrypted_name) = kmalloc(length + 2, GFP_KERNEL);
-	if (!(*decrypted_name)) {
-		error = -ENOMEM;
-		goto out;
-	}
-	/* TODO: Filename encryption is a scheduled feature for a
-	 * future version of eCryptfs. This function is here only for
-	 * the purpose of providing a framework for other developers
-	 * to easily implement filename encryption. Hint: Replace this
-	 * memcpy() with a call to decode and decrypt the
-	 * filename, the set the length accordingly. */
-	memcpy((void *)(*decrypted_name), (void *)name, length);
-	(*decrypted_name)[length + 1] = '\0';	/* Only for convenience
-						 * in printing out the
-						 * string in debug
-						 * messages */
-	error = length;
-out:
-	return error;
-}
-
 /**
  * ecryptfs_encrypt_filename - encrypt filename
  *

fs/ecryptfs/ecryptfs_kernel.h

@@ -627,12 +627,6 @@ int ecryptfs_decode_and_decrypt_filename(char **decrypted_name,
 					 struct dentry *ecryptfs_dentry,
 					 const char *name, size_t name_size);
 int ecryptfs_fill_zeros(struct file *file, loff_t new_length);
-int ecryptfs_decode_filename(struct ecryptfs_crypt_stat *crypt_stat,
-			     const char *name, int length,
-			     char **decrypted_name);
-int ecryptfs_encode_filename(struct ecryptfs_crypt_stat *crypt_stat,
-			     const char *name, int length,
-			     char **encoded_name);
 int ecryptfs_encrypt_and_encode_filename(
 	char **encoded_name,
 	size_t *encoded_name_size,

fs/ecryptfs/file.c

@@ -77,27 +77,27 @@ struct ecryptfs_getdents_callback {
 
 /* Inspired by generic filldir in fs/readdir.c */
 static int
-ecryptfs_filldir(void *dirent, const char *name, int namelen, loff_t offset,
-		 u64 ino, unsigned int d_type)
+ecryptfs_filldir(void *dirent, const char *lower_name, int lower_namelen,
+		 loff_t offset, u64 ino, unsigned int d_type)
 {
-	struct ecryptfs_crypt_stat *crypt_stat;
 	struct ecryptfs_getdents_callback *buf =
 	    (struct ecryptfs_getdents_callback *)dirent;
+	int name_size;
+	char *name;
 	int rc;
-	int decoded_length;
-	char *decoded_name;
 
-	crypt_stat = ecryptfs_dentry_to_private(buf->dentry)->crypt_stat;
 	buf->filldir_called++;
-	decoded_length = ecryptfs_decode_filename(crypt_stat, name, namelen,
-						  &decoded_name);
-	if (decoded_length < 0) {
-		rc = decoded_length;
+	rc = ecryptfs_decode_and_decrypt_filename(&name, &name_size,
+						  buf->dentry, lower_name,
+						  lower_namelen);
+	if (rc) {
+		printk(KERN_ERR "%s: Error attempting to decode and decrypt "
+		       "filename [%s]; rc = [%d]\n", __func__, lower_name,
+		       rc);
 		goto out;
 	}
-	rc = buf->filldir(buf->dirent, decoded_name, decoded_length, offset,
-			  ino, d_type);
-	kfree(decoded_name);
+	rc = buf->filldir(buf->dirent, name, name_size, offset, ino, d_type);
+	kfree(name);
 	if (rc >= 0)
 		buf->entries_written++;
 out:
@@ -106,8 +106,8 @@ ecryptfs_filldir(void *dirent, const char *name, int namelen, loff_t offset,
 
 /**
  * ecryptfs_readdir
- * @file: The ecryptfs file struct
- * @dirent: Directory entry
+ * @file: The eCryptfs directory file
+ * @dirent: Directory entry handle
  * @filldir: The filldir callback function
  */
 static int ecryptfs_readdir(struct file *file, void *dirent, filldir_t filldir)