Robert Shearman <rshea...@brocade.com> writes:
> The lwt implementations using net devices can autoload using the
> existing mechanism using IFLA_INFO_KIND. However, there's no mechanism
> that lwt modules not using net devices can use.
>
> Therefore, add the ability to autoload modules registering lwt
> operations for lwt implementations not using a net device so that
> users don't have to manually load the modules.
>
> Signed-off-by: Robert Shearman <rshea...@brocade.com>
> ---
> include/net/lwtunnel.h | 4 +++-
> net/core/lwtunnel.c | 32 ++++++++++++++++++++++++++++++++
> 2 files changed, 35 insertions(+), 1 deletion(-)
>
> diff --git a/include/net/lwtunnel.h b/include/net/lwtunnel.h
> index 66350ce3e955..e9f116e29c22 100644
> --- a/include/net/lwtunnel.h
> +++ b/include/net/lwtunnel.h
> @@ -170,6 +170,8 @@ static inline int lwtunnel_input(struct sk_buff *skb)
> return -EOPNOTSUPP;
> }
>
> -#endif
> +#endif /* CONFIG_LWTUNNEL */
> +
> +#define MODULE_ALIAS_RTNL_LWT(encap_type) MODULE_ALIAS("rtnl-lwt-"
> __stringify(encap_type))
>
> #endif /* __NET_LWTUNNEL_H */
> diff --git a/net/core/lwtunnel.c b/net/core/lwtunnel.c
> index 299cfc24d888..8ef5e5cec03e 100644
> --- a/net/core/lwtunnel.c
> +++ b/net/core/lwtunnel.c
> @@ -27,6 +27,30 @@
> #include <net/rtnetlink.h>
> #include <net/ip6_fib.h>
>
> +#ifdef CONFIG_MODULES
> +
> +static const char *lwtunnel_encap_str(enum lwtunnel_encap_types encap_type)
> +{
> + switch (encap_type) {
> + case LWTUNNEL_ENCAP_MPLS:
> + return "LWTUNNEL_ENCAP_MPLS";
> + case LWTUNNEL_ENCAP_IP:
> + return "LWTUNNEL_ENCAP_IP";
> + case LWTUNNEL_ENCAP_ILA:
> + return "LWTUNNEL_ENCAP_ILA";
> + case LWTUNNEL_ENCAP_IP6:
> + return "LWTUNNEL_ENCAP_IP6";
> + case LWTUNNEL_ENCAP_NONE:
> + case __LWTUNNEL_ENCAP_MAX:
> + /* should not have got here */
> + break;
> + }
> + WARN_ON(1);
> + return "LWTUNNEL_ENCAP_NONE";
> +}
> +
> +#endif /* CONFIG_MODULES */
> +
> struct lwtunnel_state *lwtunnel_state_alloc(int encap_len)
> {
> struct lwtunnel_state *lws;
> @@ -85,6 +109,14 @@ int lwtunnel_build_state(struct net_device *dev, u16
> encap_type,
> ret = -EOPNOTSUPP;
> rcu_read_lock();
> ops = rcu_dereference(lwtun_encaps[encap_type]);
> +#ifdef CONFIG_MODULES
> + if (!ops) {
> + rcu_read_unlock();
> + request_module("rtnl-lwt-%s", lwtunnel_encap_str(encap_type));
> + rcu_read_lock();
> + ops = rcu_dereference(lwtun_encaps[encap_type]);
> + }
> +#endif
> if (likely(ops && ops->build_state))
> ret = ops->build_state(dev, encap, family, cfg, lws);
> rcu_read_unlock();
My memory is fuzzy on how this is done elsewhere but this looks like it
needs a capability check to ensure that non-root user's can't trigger
this.
It tends to be problematic if a non-root user can trigger an autoload of
a known-buggy module. With a combination of user namespaces and network
namespaces unprivileged users can cause just about every corner of the
network stack to be exercised.
Eric
