Re: [PATCH v2 11/14] networking: Update to register_net_sysctl_sz

Joel Granados
2023-08-08T17:46:50Z

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On Tue, Aug 08, 2023 at 01:20:36PM +0200, Przemek Kitszel wrote:
> On 7/31/23 09:17, Joel Granados wrote:
> > Move from register_net_sysctl to register_net_sysctl_sz for all the
> > networking related files. Do this while making sure to mirror the NULL
> > assignments with a table_size of zero for the unprivileged users.
> >
...
> > const char *dev_name_source;
> > char neigh_path[ sizeof("net//neigh/") + IFNAMSIZ + IFNAMSIZ ];
> > char *p_name;
> > + size_t neigh_vars_size;
> > t = kmemdup(&neigh_sysctl_template, sizeof(*t), GFP_KERNEL_ACCOUNT);
> > if (!t)
> > @@ -3790,11 +3791,13 @@ int neigh_sysctl_register(struct net_device *dev, struct neigh_parms *p,
> > t->neigh_vars[i].extra2 = p;
> > }
> > + neigh_vars_size = ARRAY_SIZE(t->neigh_vars);
> > if (dev) {
> > dev_name_source = dev->name;
> > /* Terminate the table early */
> > memset(&t->neigh_vars[NEIGH_VAR_GC_INTERVAL], 0,
> > sizeof(t->neigh_vars[NEIGH_VAR_GC_INTERVAL]));
> > + neigh_vars_size = NEIGH_VAR_BASE_REACHABLE_TIME_MS;
>
> %NEIGH_VAR_BASE_REACHABLE_TIME_MS is last usable index here, and since those
> are 0 based, size is one more, %NEIGH_VAR_GC_INTERVAL.
> (spelling it "NEIGH_VAR_BASE_REACHABLE_TIME_MS+1" would be perhaps better?)
This is a very good catch. Thx for this!! I'll correct here and double
check all the other places where I'm trying to replace the memset with a
enumeration element. Just to make sure that I don't have an "off by one"
like the one here.

>
> > } else {
> > struct neigh_table *tbl = p->tbl;
> > dev_name_source = "default";
> > @@ -3841,8 +3844,9 @@ int neigh_sysctl_register(struct net_device *dev, struct neigh_parms *p,
> > snprintf(neigh_path, sizeof(neigh_path), "net/%s/neigh/%s",
> > p_name, dev_name_source);
> > - t->sysctl_header =
> > - register_net_sysctl(neigh_parms_net(p), neigh_path, t->neigh_vars);
> > + t->sysctl_header = register_net_sysctl_sz(neigh_parms_net(p),
> > + neigh_path, t->neigh_vars,
> > + neigh_vars_size);
> > if (!t->sysctl_header)
> > goto free;
> > diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
> > index 782273bb93c2..03f1edb948d7 100644

...

> > {
> > struct ctl_table *table;
> > + size_t table_size = ARRAY_SIZE(xfrm_table);
> > __xfrm_sysctl_init(net);
> > @@ -56,10 +57,13 @@ int __net_init xfrm_sysctl_init(struct net *net)
> > table[3].data = &net->xfrm.sysctl_acq_expires;
> > /* Don't export sysctls to unprivileged users */
> > - if (net->user_ns != &init_user_ns)
> > + if (net->user_ns != &init_user_ns) {
> > table[0].procname = NULL;
>
> do we still have to set procname to NULL, even if passed size is 0?
> (same thing for all earlier occurences)
Yes, we still need to set the procname to NULL in this patchest!. We are
introducing the ARRAY_SIZE but not actually using it (not yet). Keeping
the "procname == NULL" stopping criteria allows us to keep the current
behavior while we introduce the size in the background. We will start
using the patchset in the upcoming patchsets.

>
> > + table_size = 0;
> > + }
> > - net->xfrm.sysctl_hdr = register_net_sysctl(net, "net/core", table);
> > + net->xfrm.sysctl_hdr = register_net_sysctl_sz(net, "net/core", table,
> > + table_size);
> > if (!net->xfrm.sysctl_hdr)
> > goto out_register;
> > return 0;
>
> overall this patch looks sane, and whole series looks very promissing,
> thanks

Thx for the feedback

Best

--

Joel Granados

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