On 1/23/24 6:17 PM, Amir Goldstein wrote:
> If you somehow find a way to mitigate the regression for NFS export of
> old fuse servers (maybe an opt-in Kconfig?), your patch is also going to
> regress AT_HANDLE_FID functionality, which can be used by fanotify to
> monitor fuse.
>
> AT_HANDLE_FID flag to name_to_handle_at(2) means that
> open_by_handle_at(2) is not supposed to be called on that fh.
>
> The correct way to deal with that would be something like this:
>
> +static const struct export_operations fuse_fid_operations = {
> + .encode_fh = fuse_encode_fh,
> +};
> +
> static const struct export_operations fuse_export_operations = {
> .fh_to_dentry = fuse_fh_to_dentry,
> .fh_to_parent = fuse_fh_to_parent,
> @@ -1529,12 +1533,16 @@ static void fuse_fill_attr_from_inode(struct
> fuse_attr *attr,
>
> static void fuse_sb_defaults(struct super_block *sb)
> {
> + struct fuse_mount *fm = get_fuse_mount_super(sb);
> +
> sb->s_magic = FUSE_SUPER_MAGIC;
> sb->s_op = &fuse_super_operations;
> sb->s_xattr = fuse_xattr_handlers;
> sb->s_maxbytes = MAX_LFS_FILESIZE;
> sb->s_time_gran = 1;
> - sb->s_export_op = &fuse_export_operations;
> + if (fm->fc->export_support)
> + sb->s_export_op = &fuse_export_operations;
> + else
> + sb->s_export_op = &fuse_fid_operations;
> sb->s_iflags |= SB_I_IMA_UNVERIFIABLE_SIGNATURE;
> if (sb->s_user_ns != &init_user_ns)
> sb->s_iflags |= SB_I_UNTRUSTED_MOUNTER;
>
> ---
>
> This would make name_to_handle_at() without AT_HANDLE_FID fail
> and name_to_handle_at() with AT_HANDLE_FID to succeed as it should.
>
Oh I didn't notice this. Many thanks!
--
Thanks,
Jingbo
