btrfs: defrag: reject unknown flags of btrfs_ioctl_defrag_range_args

Add extra sanity check for btrfs_ioctl_defrag_range_args::flags.

This is not really to enhance fuzzing tests, but as a preparation for
future expansion on btrfs_ioctl_defrag_range_args.

In the future we're going to add new members, allowing more fine tuning
for btrfs defrag.  Without the -ENONOTSUPP error, there would be no way
to detect if the kernel supports those new defrag features.

CC: [email protected] # 4.14+
Reviewed-by: Filipe Manana <[email protected]>
Signed-off-by: Qu Wenruo <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index fea5d37528b808c73c85fbb34a2e43be6555e714..5d42319b43f2ddea959f56e23dff8be5eb907ae0 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2602,6 +2602,10 @@ static int btrfs_ioctl_defrag(struct file *file, void __user *argp)
                                ret = -EFAULT;
                                goto out;
                        }
+                       if (range.flags & ~BTRFS_DEFRAG_RANGE_FLAGS_SUPP) {
+                               ret = -EOPNOTSUPP;
+                               goto out;
+                       }
                        /* compression requires us to start the IO */
                        if ((range.flags & BTRFS_DEFRAG_RANGE_COMPRESS)) {
                                range.flags |= BTRFS_DEFRAG_RANGE_START_IO;

diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index 7c29d82db9ee0dcb5ce770b384149c9734a50f30..f8bc34a6bcfa2f7313f2e9eac38e2df6a25aafca 100644 (file)
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -614,6 +614,9 @@ struct btrfs_ioctl_clone_range_args {
  */
 #define BTRFS_DEFRAG_RANGE_COMPRESS 1
 #define BTRFS_DEFRAG_RANGE_START_IO 2
+#define BTRFS_DEFRAG_RANGE_FLAGS_SUPP  (BTRFS_DEFRAG_RANGE_COMPRESS |          \
+                                        BTRFS_DEFRAG_RANGE_START_IO)
+
 struct btrfs_ioctl_defrag_range_args {
        /* start of the defrag operation */
        __u64 start;