On Mon, Mar 22, 2021 at 03:48:59PM +0100, Miklos Szeredi wrote:
minor nit: copy_fsxattr_{to,from}_user() might be better.
> +int fsxattr_copy_to_user(const struct miscattr *ma, struct fsxattr __user *ufa)
> +{
> + struct fsxattr fa = {
> + .fsx_xflags = ma->fsx_xflags,
> + .fsx_extsize = ma->fsx_extsize,
> + .fsx_nextents = ma->fsx_nextents,
> + .fsx_projid = ma->fsx_projid,
> + .fsx_cowextsize = ma->fsx_cowextsize,
> + };
That wants a comment along the lines of "guaranteed to be gap-free",
since otherwise you'd need memset() to avoid an infoleak.
> +static int ioctl_getflags(struct file *file, void __user *argp)
> +{
> + struct miscattr ma = { .flags_valid = true }; /* hint only */
> + unsigned int flags;
> + int err;
> +
> + err = vfs_miscattr_get(file_dentry(file), &ma);
Umm... Just to clarify - do we plan to have that ever called via
ovl_real_ioctl()? IOW, is file_dentry() anything other than a way
to spell ->f_path.dentry here?
> +struct miscattr {
> + u32 flags; /* flags (FS_IOC_GETFLAGS/FS_IOC_SETFLAGS) */
> + /* struct fsxattr: */
> + u32 fsx_xflags; /* xflags field value (get/set) */
> + u32 fsx_extsize; /* extsize field value (get/set)*/
> + u32 fsx_nextents; /* nextents field value (get) */
> + u32 fsx_projid; /* project identifier (get/set) */
> + u32 fsx_cowextsize; /* CoW extsize field value (get/set)*/
> + /* selectors: */
> + bool flags_valid:1;
> + bool xattr_valid:1;
> +};
OK as long as it stays kernel-only, but if we ever expose that to userland, we'd
better remember to turn the last two into an u32 with explicit bitmasks.
