On Tue, Jan 26, 2021 at 10:01 AM Martin KaFai Lau <kafai@xxxxxx> wrote:
>
> On Tue, Jan 26, 2021 at 08:51:03AM -0800, Stanislav Fomichev wrote:
> > At the moment, BPF_CGROUP_INET{4,6}_BIND hooks can rewrite user_port
> > to the privileged ones (< ip_unprivileged_port_start), but it will
> > be rejected later on in the __inet_bind or __inet6_bind.
> >
> > Let's add another return value to indicate that CAP_NET_BIND_SERVICE
> > check should be ignored. Use the same idea as we currently use
> > in cgroup/egress where bit #1 indicates CN. Instead, for
> > cgroup/bind{4,6}, bit #1 indicates that CAP_NET_BIND_SERVICE should
> > be bypassed.
> >
> > v3:
> > - Update description (Martin KaFai Lau)
> > - Fix capability restore in selftest (Martin KaFai Lau)
> >
> > v2:
> > - Switch to explicit return code (Martin KaFai Lau)
> >
>
> [ ... ]
>
> > @@ -499,7 +501,8 @@ int __inet_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len,
> >
> > snum = ntohs(addr->sin_port);
> > err = -EACCES;
> > - if (snum && inet_port_requires_bind_service(net, snum) &&
> > + if (!(flags & BIND_NO_CAP_NET_BIND_SERVICE) &&
> > + snum && inet_port_requires_bind_service(net, snum) &&
> The same change needs to be done on __inet6_bind()
> and also adds a test for IPv6 in patch 2.
Oh, damn, I did add the flag but forgot to handle it. Thanks for
catching this, will do!
