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

[Mat Martineau <mathew.j.martineau@linux.intel.com>]

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?).

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?


Thanks,
Mat


> ---
> 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