[PATCH v4 16/46] btrfs: implement fscrypt ioctls

[Josef Bacik <josef@toxicpanda.com>]

From: Omar Sandoval <osandov@osandov.com>

These ioctls allow encryption to actually be used.

The set_encryption_policy ioctl is the thing which actually turns on
encryption, and therefore sets the ENCRYPT flag in the superblock. This
prevents the filesystem from being loaded on older kernels.

fscrypt provides CONFIG_FS_ENCRYPTION-disabled versions of all these
functions which just return -EOPNOTSUPP, so the ioctls don't need to be
compiled out if CONFIG_FS_ENCRYPTION isn't enabled.

We could instead gate this ioctl on the superblock having the flag set,
if we wanted to require mkfs with the encrypt flag in order to have a
filesystem with any encryption.

Signed-off-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
 fs/btrfs/ioctl.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 6acf898f693e..9968a36079c4 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -4573,6 +4573,34 @@ long btrfs_ioctl(struct file *file, unsigned int
 		return btrfs_ioctl_get_fslabel(fs_info, argp);
 	case FS_IOC_SETFSLABEL:
 		return btrfs_ioctl_set_fslabel(file, argp);
+	case FS_IOC_SET_ENCRYPTION_POLICY: {
+		if (!IS_ENABLED(CONFIG_FS_ENCRYPTION))
+			return -EOPNOTSUPP;
+		if (sb_rdonly(fs_info->sb))
+			return -EROFS;
+		/*
+		 *  If we crash before we commit, nothing encrypted could have
+		 * been written so it doesn't matter whether the encrypted
+		 * state persists.
+		 */
+		btrfs_set_fs_incompat(fs_info, ENCRYPT);
+		return fscrypt_ioctl_set_policy(file, (const void __user *)arg);
+	}
+	case FS_IOC_GET_ENCRYPTION_POLICY:
+		return fscrypt_ioctl_get_policy(file, (void __user *)arg);
+	case FS_IOC_GET_ENCRYPTION_POLICY_EX:
+		return fscrypt_ioctl_get_policy_ex(file, (void __user *)arg);
+	case FS_IOC_ADD_ENCRYPTION_KEY:
+		return fscrypt_ioctl_add_key(file, (void __user *)arg);
+	case FS_IOC_REMOVE_ENCRYPTION_KEY:
+		return fscrypt_ioctl_remove_key(file, (void __user *)arg);
+	case FS_IOC_REMOVE_ENCRYPTION_KEY_ALL_USERS:
+		return fscrypt_ioctl_remove_key_all_users(file,
+							  (void __user *)arg);
+	case FS_IOC_GET_ENCRYPTION_KEY_STATUS:
+		return fscrypt_ioctl_get_key_status(file, (void __user *)arg);
+	case FS_IOC_GET_ENCRYPTION_NONCE:
+		return fscrypt_ioctl_get_nonce(file, (void __user *)arg);
 	case FITRIM:
 		return btrfs_ioctl_fitrim(fs_info, argp);
 	case BTRFS_IOC_SNAP_CREATE:
-- 
2.41.0