Merge tag 'ecryptfs-4.17-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tyhicks/ecryptfs

Pull eCryptfs fixes from Tyler Hicks:
 "Minor cleanups and a bug fix to completely ignore unencrypted
  filenames in the lower filesystem when filename encryption is enabled
  at the eCryptfs layer"

* tag 'ecryptfs-4.17-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tyhicks/ecryptfs:
  eCryptfs: don't pass up plaintext names when using filename encryption
  ecryptfs: fix spelling mistake: "cadidate" -> "candidate"
  ecryptfs: lookup: Don't check if mount_crypt_stat is NULL

fs/ecryptfs/crypto.c

@@ -1997,6 +1997,16 @@ out:
 	return rc;
 }
 
+static bool is_dot_dotdot(const char *name, size_t name_size)
+{
+	if (name_size == 1 && name[0] == '.')
+		return true;
+	else if (name_size == 2 && name[0] == '.' && name[1] == '.')
+		return true;
+
+	return false;
+}
+
 /**
  * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
  * @plaintext_name: The plaintext name
@@ -2021,13 +2031,21 @@ int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
 	size_t packet_size;
 	int rc = 0;
 
-	if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
-	    && !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
-	    && (name_size > ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)
-	    && (strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
-			ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE) == 0)) {
-		const char *orig_name = name;
-		size_t orig_name_size = name_size;
+	if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) &&
+	    !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)) {
+		if (is_dot_dotdot(name, name_size)) {
+			rc = ecryptfs_copy_filename(plaintext_name,
+						    plaintext_name_size,
+						    name, name_size);
+			goto out;
+		}
+
+		if (name_size <= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE ||
+		    strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
+			    ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)) {
+			rc = -EINVAL;
+			goto out;
+		}
 
 		name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
 		name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
@@ -2047,12 +2065,9 @@ int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
 						  decoded_name,
 						  decoded_name_size);
 		if (rc) {
-			printk(KERN_INFO "%s: Could not parse tag 70 packet "
-			       "from filename; copying through filename "
-			       "as-is\n", __func__);
-			rc = ecryptfs_copy_filename(plaintext_name,
-						    plaintext_name_size,
-						    orig_name, orig_name_size);
+			ecryptfs_printk(KERN_DEBUG,
+					"%s: Could not parse tag 70 packet from filename\n",
+					__func__);
 			goto out_free;
 		}
 	} else {

fs/ecryptfs/file.c

@@ -82,17 +82,28 @@ ecryptfs_filldir(struct dir_context *ctx, const char *lower_name,
 						  buf->sb, 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;
+		if (rc != -EINVAL) {
+			ecryptfs_printk(KERN_DEBUG,
+					"%s: Error attempting to decode and decrypt filename [%s]; rc = [%d]\n",
+					__func__, lower_name, rc);
+			return rc;
+		}
+
+		/* Mask -EINVAL errors as these are most likely due a plaintext
+		 * filename present in the lower filesystem despite filename
+		 * encryption being enabled. One unavoidable example would be
+		 * the "lost+found" dentry in the root directory of an Ext4
+		 * filesystem.
+		 */
+		return 0;
 	}
+
 	buf->caller->pos = buf->ctx.pos;
 	rc = !dir_emit(buf->caller, name, name_size, ino, d_type);
 	kfree(name);
 	if (!rc)
 		buf->entries_written++;
-out:
+
 	return rc;
 }
 

fs/ecryptfs/inode.c

@@ -395,8 +395,7 @@ static struct dentry *ecryptfs_lookup(struct inode *ecryptfs_dir_inode,
 
 	mount_crypt_stat = &ecryptfs_superblock_to_private(
 				ecryptfs_dentry->d_sb)->mount_crypt_stat;
-	if (mount_crypt_stat
-	    && (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
+	if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
 		rc = ecryptfs_encrypt_and_encode_filename(
 			&encrypted_and_encoded_name, &len,
 			mount_crypt_stat, name, len);

fs/ecryptfs/keystore.c

@@ -1880,7 +1880,7 @@ find_next_matching_auth_tok:
 		candidate_auth_tok = &auth_tok_list_item->auth_tok;
 		if (unlikely(ecryptfs_verbosity > 0)) {
 			ecryptfs_printk(KERN_DEBUG,
-					"Considering cadidate auth tok:\n");
+					"Considering candidate auth tok:\n");
 			ecryptfs_dump_auth_tok(candidate_auth_tok);
 		}
 		rc = ecryptfs_get_auth_tok_sig(&candidate_auth_tok_sig,