2007-11-23 19:27:18

by Eric W. Biederman

Subject: [PATCH] utsns: Restore proper namespace handling.

When CONFIG_UTS_NS was removed it seems that we also deleted
the code for handling sysctls in the other then the initial
uts namespace. This patch restores that code.

Signed-off-by: Eric W. Biederman <[email protected]>
---
kernel/utsname_sysctl.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/kernel/utsname_sysctl.c b/kernel/utsname_sysctl.c
index c76c064..71f58c3 100644
--- a/kernel/utsname_sysctl.c
+++ b/kernel/utsname_sysctl.c
@@ -18,6 +18,8 @@
static void *get_uts(ctl_table *table, int write)
{
char *which = table->data;
+ struct uts_namespace *uts_ns = current->nsproxy->uts_ns;
+ which = (which - (char *)&init_uts_ns) + (char *)uts_ns;

if (!write)
down_read(&uts_sem);
--
1.5.3.rc6.17.g1911

2007-11-26 15:19:31

by Serge E. Hallyn

Subject: Re: [PATCH] utsns: Restore proper namespace handling.

Quoting Eric W. Biederman ([email protected]):
>
> When CONFIG_UTS_NS was removed it seems that we also deleted
> the code for handling sysctls in the other then the initial
> uts namespace. This patch restores that code.
>
> Signed-off-by: Eric W. Biederman <[email protected]>

Thanks, Eric.

Acked-by: Serge Hallyn <[email protected]>

> ---
> kernel/utsname_sysctl.c | 2 ++
> 1 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/kernel/utsname_sysctl.c b/kernel/utsname_sysctl.c
> index c76c064..71f58c3 100644
> --- a/kernel/utsname_sysctl.c
> +++ b/kernel/utsname_sysctl.c
> @@ -18,6 +18,8 @@
> static void *get_uts(ctl_table *table, int write)
> {
> char *which = table->data;
> + struct uts_namespace *uts_ns = current->nsproxy->uts_ns;
> + which = (which - (char *)&init_uts_ns) + (char *)uts_ns;
>
> if (!write)
> down_read(&uts_sem);
> --
> 1.5.3.rc6.17.g1911
>
> _______________________________________________
> Containers mailing list
> [email protected]
> https://lists.linux-foundation.org/mailman/listinfo/containers

2007-11-27 06:56:10

by Andrew Morton

Subject: Re: [PATCH] utsns: Restore proper namespace handling.

On Mon, 26 Nov 2007 09:19:17 -0600 "Serge E. Hallyn" <[email protected]> wrote:

> Quoting Eric W. Biederman ([email protected]):
> >
> > When CONFIG_UTS_NS was removed it seems that we also deleted
> > the code for handling sysctls in the other then the initial
> > uts namespace. This patch restores that code.
> >
> > Signed-off-by: Eric W. Biederman <[email protected]>
>
> Thanks, Eric.
>
> Acked-by: Serge Hallyn <[email protected]>
>
> > ---
> > kernel/utsname_sysctl.c | 2 ++
> > 1 files changed, 2 insertions(+), 0 deletions(-)
> >
> > diff --git a/kernel/utsname_sysctl.c b/kernel/utsname_sysctl.c
> > index c76c064..71f58c3 100644
> > --- a/kernel/utsname_sysctl.c
> > +++ b/kernel/utsname_sysctl.c
> > @@ -18,6 +18,8 @@
> > static void *get_uts(ctl_table *table, int write)
> > {
> > char *which = table->data;
> > + struct uts_namespace *uts_ns = current->nsproxy->uts_ns;
> > + which = (which - (char *)&init_uts_ns) + (char *)uts_ns;
> >
> > if (!write)
> > down_read(&uts_sem);

I already have a (more codingstylely attractive) version of this from
Pavel, for which I shall steal your ack.

--- a/kernel/utsname_sysctl.c~isolate-the-uts-namespaces-domainname-and-hostname-back
+++ a/kernel/utsname_sysctl.c
@@ -18,6 +18,10 @@
static void *get_uts(ctl_table *table, int write)
{
char *which = table->data;
+ struct uts_namespace *uts_ns;
+
+ uts_ns = current->nsproxy->uts_ns;
+ which = (which - (char *)&init_uts_ns) + (char *)uts_ns;

if (!write)
down_read(&uts_sem);
_


Those pointer tricksies are revolting. What's going on in there?

2007-11-27 09:22:26

by Eric W. Biederman

Subject: Re: [PATCH] utsns: Restore proper namespace handling.

Andrew Morton <[email protected]> writes:


> I already have a (more codingstylely attractive) version of this from
> Pavel, for which I shall steal your ack.

Perfectly fine. I overlooked that one when I generated this patch
the first time (Oops). Let's just get this bug fixed.

Eric

2007-11-27 16:28:42

by Serge E. Hallyn

Subject: Re: [PATCH] utsns: Restore proper namespace handling.

Quoting Andrew Morton ([email protected]):
> On Mon, 26 Nov 2007 09:19:17 -0600 "Serge E. Hallyn" <[email protected]> wrote:
>
> > Quoting Eric W. Biederman ([email protected]):
> > >
> > > When CONFIG_UTS_NS was removed it seems that we also deleted
> > > the code for handling sysctls in the other then the initial
> > > uts namespace. This patch restores that code.
> > >
> > > Signed-off-by: Eric W. Biederman <[email protected]>
> >
> > Thanks, Eric.
> >
> > Acked-by: Serge Hallyn <[email protected]>
> >
> > > ---
> > > kernel/utsname_sysctl.c | 2 ++
> > > 1 files changed, 2 insertions(+), 0 deletions(-)
> > >
> > > diff --git a/kernel/utsname_sysctl.c b/kernel/utsname_sysctl.c
> > > index c76c064..71f58c3 100644
> > > --- a/kernel/utsname_sysctl.c
> > > +++ b/kernel/utsname_sysctl.c
> > > @@ -18,6 +18,8 @@
> > > static void *get_uts(ctl_table *table, int write)
> > > {
> > > char *which = table->data;
> > > + struct uts_namespace *uts_ns = current->nsproxy->uts_ns;
> > > + which = (which - (char *)&init_uts_ns) + (char *)uts_ns;
> > >
> > > if (!write)
> > > down_read(&uts_sem);
>
> I already have a (more codingstylely attractive) version of this from
> Pavel, for which I shall steal your ack.

Cool, thanks.

> --- a/kernel/utsname_sysctl.c~isolate-the-uts-namespaces-domainname-and-hostname-back
> +++ a/kernel/utsname_sysctl.c
> @@ -18,6 +18,10 @@
> static void *get_uts(ctl_table *table, int write)
> {
> char *which = table->data;
> + struct uts_namespace *uts_ns;
> +
> + uts_ns = current->nsproxy->uts_ns;
> + which = (which - (char *)&init_uts_ns) + (char *)uts_ns;
>
> if (!write)
> down_read(&uts_sem);
> _
>
>
> Those pointer tricksies are revolting. What's going on in there?

This is true. There is only one sysctl table, and it's data points
to the location of the desired field in the initial namespace. So
the trickery finds the same field in the target namespace.

I believe Eric and Pavel are working on a patchset that will make
this trickery unnecessary by having sort of shadow sysctls.

-serge