Re: [PATCH] mptcp: allow priviledged operations from user namespaces

[Thomas Haller <thaller@redhat.com>]

Hi Mat,

On Mon, 2022-08-08 at 17:04 -0700, Mat Martineau wrote:
> On Fri, 5 Aug 2022, Thomas Haller wrote:
> 
> > GENL_ADMIN_PERM checks that the user has CAP_NET_ADMIN in the
> > initial
> > namespace by calling netlink_capable(). Instead, use
> > GENL_UNS_ADMIN_PERM
> > which uses netlink_ns_capable(). This checks that the caller has
> > CAP_NET_ADMIN in the current user namespace.
> > 
> > See also commit 4a92602aa1cd ('openvswitch: allow management from
> > inside
> > user namespaces') which introduced this mechanism. See also commit
> > 5617c6cd6f84 ('nl80211: Allow privileged operations from user
> > namespaces'), which introduced this for nl80211.
> > 
> > Signed-off-by: Thomas Haller <thaller@redhat.com>
> 
> Hi Thomas -
> 
> Thanks for the patch! This does seem like a good idea to me (and it
> seems 
> to work ok with our MPTCP tests), but I'd like to get some more
> community 
> input before merging (Paolo/Florian?).

thanks for your feedback.

The background for this is that we run unit tests for NetworkManager in
a separate network namespace, started as non-root user. Configuring
MPTCP endpoints does currently not work in that environment.


> We also need to figure out which branch this belongs in (we usually
> tag 
> the patch subject with [PATCH mptcp-net] or [PATCH mptcp-next] to
> indicate 
> this). If we upstream it to the net branch it will get in to 6.0-rcX
> and 
> be eligible for backporting to the stable branches. Looks like it
> would 
> need manual backporting to pre-5.19 kernels due to the incremental
> changes 
> to mptcp_pm_ops over time.

> To upstream this to net it also needs a Fixes tag:
> 
> Fixes: 702c2f646d42 ("mptcp: netlink: allow userspace-driven subflow
> establishment")


> Thomas, do you have any thoughts/preferences on upstreaming to net or
> net-next?

I don't have a strong opinion or need. Thanks for explaining the
process.

Ffrom what you said, it sounds as this would make sense as [PATCH
mptcp-net]. I will send a v2 with the "Fixes:" line.



Thomas

> > ---
> > net/mptcp/pm_netlink.c | 18 +++++++++---------
> > 1 file changed, 9 insertions(+), 9 deletions(-)
> > 
> > diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
> > index 291b5da42fdb..2c145cdc7bdc 100644
> > --- a/net/mptcp/pm_netlink.c
> > +++ b/net/mptcp/pm_netlink.c
> > @@ -2218,17 +2218,17 @@ static const struct genl_small_ops
> > mptcp_pm_ops[] = {
> >         {
> >                 .cmd    = MPTCP_PM_CMD_ADD_ADDR,
> >                 .doit   = mptcp_nl_cmd_add_addr,
> > -               .flags  = GENL_ADMIN_PERM,
> > +               .flags  = GENL_UNS_ADMIN_PERM,
> >         },
> >         {
> >                 .cmd    = MPTCP_PM_CMD_DEL_ADDR,
> >                 .doit   = mptcp_nl_cmd_del_addr,
> > -               .flags  = GENL_ADMIN_PERM,
> > +               .flags  = GENL_UNS_ADMIN_PERM,
> >         },
> >         {
> >                 .cmd    = MPTCP_PM_CMD_FLUSH_ADDRS,
> >                 .doit   = mptcp_nl_cmd_flush_addrs,
> > -               .flags  = GENL_ADMIN_PERM,
> > +               .flags  = GENL_UNS_ADMIN_PERM,
> >         },
> >         {
> >                 .cmd    = MPTCP_PM_CMD_GET_ADDR,
> > @@ -2238,7 +2238,7 @@ static const struct genl_small_ops
> > mptcp_pm_ops[] = {
> >         {
> >                 .cmd    = MPTCP_PM_CMD_SET_LIMITS,
> >                 .doit   = mptcp_nl_cmd_set_limits,
> > -               .flags  = GENL_ADMIN_PERM,
> > +               .flags  = GENL_UNS_ADMIN_PERM,
> >         },
> >         {
> >                 .cmd    = MPTCP_PM_CMD_GET_LIMITS,
> > @@ -2247,27 +2247,27 @@ static const struct genl_small_ops
> > mptcp_pm_ops[] = {
> >         {
> >                 .cmd    = MPTCP_PM_CMD_SET_FLAGS,
> >                 .doit   = mptcp_nl_cmd_set_flags,
> > -               .flags  = GENL_ADMIN_PERM,
> > +               .flags  = GENL_UNS_ADMIN_PERM,
> >         },
> >         {
> >                 .cmd    = MPTCP_PM_CMD_ANNOUNCE,
> >                 .doit   = mptcp_nl_cmd_announce,
> > -               .flags  = GENL_ADMIN_PERM,
> > +               .flags  = GENL_UNS_ADMIN_PERM,
> >         },
> >         {
> >                 .cmd    = MPTCP_PM_CMD_REMOVE,
> >                 .doit   = mptcp_nl_cmd_remove,
> > -               .flags  = GENL_ADMIN_PERM,
> > +               .flags  = GENL_UNS_ADMIN_PERM,
> >         },
> >         {
> >                 .cmd    = MPTCP_PM_CMD_SUBFLOW_CREATE,
> >                 .doit   = mptcp_nl_cmd_sf_create,
> > -               .flags  = GENL_ADMIN_PERM,
> > +               .flags  = GENL_UNS_ADMIN_PERM,
> >         },
> >         {
> >                 .cmd    = MPTCP_PM_CMD_SUBFLOW_DESTROY,
> >                 .doit   = mptcp_nl_cmd_sf_destroy,
> > -               .flags  = GENL_ADMIN_PERM,
> > +               .flags  = GENL_UNS_ADMIN_PERM,
> >         },
> > };
> > 
> > -- 
> > 2.37.1
> > 
> > 
> > 
> 
> --
> Mat Martineau
> Intel
>