[Devel] Re: [PATCH 4/5] cr: checkpoint and restore task credentials

[Alexey Dobriyan]

On Thu, May 14, 2009 at 12:18:50PM +0400, Alexey Dobriyan wrote:
> On Mon, May 11, 2009 at 11:05:39AM -0500, Serge E. Hallyn wrote:
> > --- a/checkpoint/objhash.c
> > +++ b/checkpoint/objhash.c
> > +#define CKPT_MAXGROUPS 15
> > +#define MAX_GROUPINFO_SIZE (sizeof(*h)+CKPT_MAXGROUPS*sizeof(gid_t))
> > +/* move this fn into kernel/sys.c next to group functions? */
> > +static int checkpoint_write_groupinfo(struct ckpt_ctx *ctx,
> > +					struct group_info *g)
> > +{
> > +	int ret, i, size;
> > +	struct ckpt_hdr_groupinfo *h;
> > +
> > +	if (g->ngroups > CKPT_MAXGROUPS) {
> > +		ckpt_debug("Too many groups: %d  (max is %d)\n",
> > +			g->ngroups, CKPT_MAXGROUPS);
> > +		return -E2BIG;
> > +	}
> 
> Ooh, a hack :-)
> 
> > +	size = sizeof(*h) + g->ngroups * sizeof(__u32);
> > +	h = ckpt_hdr_get_type(ctx, size, CKPT_HDR_GROUPINFO);
> > +	if (!h)
> > +		return -ENOMEM;
> > +
> > +	h->ngroups = g->ngroups;
> > +	for (i = 0; i < g->ngroups; i++)
> > +		h->groups[i] = GROUP_AT(g, i);
> > +
> > +	ret = ckpt_write_obj(ctx, (struct ckpt_hdr *) h);
> > +	ckpt_hdr_put(ctx, h);
> > +
> > +	return ret;
> > +}
> 
> > +/*
> > + * write the user struct
> > + * TODO keyring will need to be dumped
> > + */
> > +#define UNSAVED_NS_MAX 5
> 
> Another hack :-)
> 
> This is an invitation to discuss what to do with references to future,
> especially given that object image can be variable-size _and_
> streamability on dump.
> 
> In case of user->user_ns->creator, we can avoid the issue and dump creator
> first.

Aieee, user_ns are also hierarchical and ->creator points to outside of
hierarchy.
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