Fixes for proper ioctl handling and an untriggerable buffer overflow

- The eCryptfs ioctl handling functions should only pass known-good ioctl
   commands to the lower filesystem
 - A static checker found a potential buffer overflow. Upon inspection, it is
   not triggerable due to input validation performed on the mount parameters.
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Merge tag 'ecryptfs-4.0-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tyhicks/ecryptfs

Pull eCryptfs fixes from Tyler Hicks:
 "Fixes for proper ioctl handling and an untriggerable buffer overflow

   - The eCryptfs ioctl handling functions should only pass known-good
     ioctl commands to the lower filesystem

   - A static checker found a potential buffer overflow.  Upon
     inspection, it is not triggerable due to input validation performed
     on the mount parameters"

* tag 'ecryptfs-4.0-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tyhicks/ecryptfs:
  eCryptfs: don't pass fs-specific ioctl commands through
  eCryptfs: ensure copy to crypt_stat->cipher does not overrun

fs/ecryptfs/ecryptfs_kernel.h

@@ -124,7 +124,7 @@ ecryptfs_get_key_payload_data(struct key *key)
 }
 
 #define ECRYPTFS_MAX_KEYSET_SIZE 1024
-#define ECRYPTFS_MAX_CIPHER_NAME_SIZE 32
+#define ECRYPTFS_MAX_CIPHER_NAME_SIZE 31
 #define ECRYPTFS_MAX_NUM_ENC_KEYS 64
 #define ECRYPTFS_MAX_IV_BYTES 16	/* 128 bits */
 #define ECRYPTFS_SALT_BYTES 2
@@ -237,7 +237,7 @@ struct ecryptfs_crypt_stat {
 	struct crypto_ablkcipher *tfm;
 	struct crypto_hash *hash_tfm; /* Crypto context for generating
 				       * the initialization vectors */
-	unsigned char cipher[ECRYPTFS_MAX_CIPHER_NAME_SIZE];
+	unsigned char cipher[ECRYPTFS_MAX_CIPHER_NAME_SIZE + 1];
 	unsigned char key[ECRYPTFS_MAX_KEY_BYTES];
 	unsigned char root_iv[ECRYPTFS_MAX_IV_BYTES];
 	struct list_head keysig_list;

fs/ecryptfs/file.c

@@ -303,9 +303,22 @@ ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	struct file *lower_file = ecryptfs_file_to_lower(file);
 	long rc = -ENOTTY;
 
-	if (lower_file->f_op->unlocked_ioctl)
+	if (!lower_file->f_op->unlocked_ioctl)
+		return rc;
+
+	switch (cmd) {
+	case FITRIM:
+	case FS_IOC_GETFLAGS:
+	case FS_IOC_SETFLAGS:
+	case FS_IOC_GETVERSION:
+	case FS_IOC_SETVERSION:
 		rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
-	return rc;
+		fsstack_copy_attr_all(file_inode(file), file_inode(lower_file));
+
+		return rc;
+	default:
+		return rc;
+	}
 }
 
 #ifdef CONFIG_COMPAT
@@ -315,9 +328,22 @@ ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	struct file *lower_file = ecryptfs_file_to_lower(file);
 	long rc = -ENOIOCTLCMD;
 
-	if (lower_file->f_op->compat_ioctl)
+	if (!lower_file->f_op->compat_ioctl)
+		return rc;
+
+	switch (cmd) {
+	case FITRIM:
+	case FS_IOC32_GETFLAGS:
+	case FS_IOC32_SETFLAGS:
+	case FS_IOC32_GETVERSION:
+	case FS_IOC32_SETVERSION:
 		rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
-	return rc;
+		fsstack_copy_attr_all(file_inode(file), file_inode(lower_file));
+
+		return rc;
+	default:
+		return rc;
+	}
 }
 #endif
 

fs/ecryptfs/keystore.c

@@ -891,7 +891,7 @@ struct ecryptfs_parse_tag_70_packet_silly_stack {
 	struct blkcipher_desc desc;
 	char fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX + 1];
 	char iv[ECRYPTFS_MAX_IV_BYTES];
-	char cipher_string[ECRYPTFS_MAX_CIPHER_NAME_SIZE];
+	char cipher_string[ECRYPTFS_MAX_CIPHER_NAME_SIZE + 1];
 };
 
 /**

fs/ecryptfs/main.c

@@ -407,7 +407,7 @@ static int ecryptfs_parse_options(struct ecryptfs_sb_info *sbi, char *options,
 	if (!cipher_name_set) {
 		int cipher_name_len = strlen(ECRYPTFS_DEFAULT_CIPHER);
 
-		BUG_ON(cipher_name_len >= ECRYPTFS_MAX_CIPHER_NAME_SIZE);
+		BUG_ON(cipher_name_len > ECRYPTFS_MAX_CIPHER_NAME_SIZE);
 		strcpy(mount_crypt_stat->global_default_cipher_name,
 		       ECRYPTFS_DEFAULT_CIPHER);
 	}