ubifs: Implement UBIFS_FLG_ENCRYPTION

This feature flag indicates that the filesystem contains encrypted
files.
Signed-off-by: Richard Weinberger <richard@nod.at>

fs/ubifs/ioctl.c

@@ -183,6 +183,7 @@ long ubifs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	}
 	case FS_IOC_SET_ENCRYPTION_POLICY: {
 #ifdef CONFIG_UBIFS_FS_ENCRYPTION
+		struct ubifs_info *c = inode->i_sb->s_fs_info;
 		struct fscrypt_policy policy;
 
 		if (copy_from_user(&policy,
@@ -190,6 +191,10 @@ long ubifs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 				   sizeof(policy)))
 			return -EFAULT;
 
+		err = ubifs_enable_encryption(c);
+		if (err)
+			return err;
+
 		err = fscrypt_process_policy(file, &policy);
 
 		return err;

fs/ubifs/sb.c

@@ -622,6 +622,16 @@ int ubifs_read_superblock(struct ubifs_info *c)
 	c->big_lpt = !!(sup_flags & UBIFS_FLG_BIGLPT);
 	c->space_fixup = !!(sup_flags & UBIFS_FLG_SPACE_FIXUP);
 	c->double_hash = !!(sup_flags & UBIFS_FLG_DOUBLE_HASH);
+	c->encrypted = !!(sup_flags & UBIFS_FLG_ENCRYPTION);
+
+#ifndef CONFIG_UBIFS_FS_ENCRYPTION
+	if (c->encrypted) {
+		ubifs_err(c, "file system contains encrypted files but UBIFS"
+			     " was built without crypto support.");
+		err = -EINVAL;
+		goto out;
+	}
+#endif
 
 	/* Automatically increase file system size to the maximum size */
 	c->old_leb_cnt = c->leb_cnt;
@@ -809,3 +819,33 @@ int ubifs_fixup_free_space(struct ubifs_info *c)
 	ubifs_msg(c, "free space fixup complete");
 	return err;
 }
+
+int ubifs_enable_encryption(struct ubifs_info *c)
+{
+	int err;
+	struct ubifs_sb_node *sup;
+
+	if (c->encrypted)
+		return 0;
+
+	if (c->ro_mount || c->ro_media)
+		return -EROFS;
+
+	if (c->fmt_version < 5) {
+		ubifs_err(c, "on-flash format version 5 is needed for encryption");
+		return -EINVAL;
+	}
+
+	sup = ubifs_read_sb_node(c);
+	if (IS_ERR(sup))
+		return PTR_ERR(sup);
+
+	sup->flags |= cpu_to_le32(UBIFS_FLG_ENCRYPTION);
+
+	err = ubifs_write_sb_node(c, sup);
+	if (!err)
+		c->encrypted = 1;
+	kfree(sup);
+
+	return err;
+}

fs/ubifs/ubifs-media.h

@@ -420,11 +420,13 @@ enum {
  * UBIFS_FLG_SPACE_FIXUP: first-mount "fixup" of free space within LEBs needed
  * UBIFS_FLG_DOUBLE_HASH: store a 32bit cookie in directory entry nodes to
  *			  support 64bit cookies for lookups by hash
+ * UBIFS_FLG_ENCRYPTION: this filesystem contains encrypted files
  */
 enum {
 	UBIFS_FLG_BIGLPT = 0x02,
 	UBIFS_FLG_SPACE_FIXUP = 0x04,
 	UBIFS_FLG_DOUBLE_HASH = 0x08,
+	UBIFS_FLG_ENCRYPTION = 0x10,
 };
 
 /**

fs/ubifs/ubifs.h

@@ -1007,6 +1007,7 @@ struct ubifs_debug_info;
  * @big_lpt: flag that LPT is too big to write whole during commit
  * @space_fixup: flag indicating that free space in LEBs needs to be cleaned up
  * @double_hash: flag indicating that we can do lookups by hash
+ * @encrypted: flag indicating that this file system contains encrypted files
  * @no_chk_data_crc: do not check CRCs when reading data nodes (except during
  *                   recovery)
  * @bulk_read: enable bulk-reads
@@ -1250,6 +1251,7 @@ struct ubifs_info {
 	unsigned int big_lpt:1;
 	unsigned int space_fixup:1;
 	unsigned int double_hash:1;
+	unsigned int encrypted:1;
 	unsigned int no_chk_data_crc:1;
 	unsigned int bulk_read:1;
 	unsigned int default_compr:2;
@@ -1649,6 +1651,7 @@ int ubifs_read_superblock(struct ubifs_info *c);
 struct ubifs_sb_node *ubifs_read_sb_node(struct ubifs_info *c);
 int ubifs_write_sb_node(struct ubifs_info *c, struct ubifs_sb_node *sup);
 int ubifs_fixup_free_space(struct ubifs_info *c);
+int ubifs_enable_encryption(struct ubifs_info *c);
 
 /* replay.c */
 int ubifs_validate_entry(struct ubifs_info *c,