Re: [PATCH v15 5/9] namei: LOOKUP_IN_ROOT: chroot-like scoped resolution

Al Viro
2019-11-13T02:03:44Z

On Tue, Nov 05, 2019 at 08:05:49PM +1100, Aleksa Sarai wrote:

> @@ -2277,12 +2277,20 @@ static const char *path_init(struct nameidata *nd, unsigned flags)
>
> nd->m_seq = read_seqbegin(&mount_lock);
>
> - /* Figure out the starting path and root (if needed). */
> - if (*s == '/') {
> + /* Absolute pathname -- fetch the root. */
> + if (flags & LOOKUP_IN_ROOT) {
> + /* With LOOKUP_IN_ROOT, act as a relative path. */
> + while (*s == '/')
> + s++;

Er... Why bother skipping slashes? I mean, not only link_path_walk()
will skip them just fine, you are actually risking breakage in this:
if (*s && unlikely(!d_can_lookup(dentry))) {
fdput(f);
return ERR_PTR(-ENOTDIR);
}
which is downstream from there with you patch, AFAICS.