| Message ID | 20240418145743.248109-2-aleksandr.mikhalitsyn@canonical.com |
|---|---|
| State | New |
| Headers | show |
| Series | [net-next,v3,1/2] ipvs: add READ_ONCE barrier for ipvs->sysctl_amemthresh | expand |
Hello, On Thu, 18 Apr 2024, Alexander Mikhalitsyn wrote: > Let's make all IPVS sysctls writtable even when > network namespace is owned by non-initial user namespace. > > Let's make a few sysctls to be read-only for non-privileged users: > - sync_qlen_max > - sync_sock_size > - run_estimation > - est_cpulist > - est_nice > > I'm trying to be conservative with this to prevent > introducing any security issues in there. Maybe, > we can allow more sysctls to be writable, but let's > do this on-demand and when we see real use-case. > > This patch is motivated by user request in the LXC > project [1]. Having this can help with running some > Kubernetes [2] or Docker Swarm [3] workloads inside the system > containers. > > Link: https://github.com/lxc/lxc/issues/4278 [1] > Link: https://github.com/kubernetes/kubernetes/blob/b722d017a34b300a2284b890448e5a605f21d01e/pkg/proxy/ipvs/proxier.go#L103 [2] > Link: https://github.com/moby/libnetwork/blob/3797618f9a38372e8107d8c06f6ae199e1133ae8/osl/namespace_linux.go#L682 [3] > > Cc: Stéphane Graber <stgraber@stgraber.org> > Cc: Christian Brauner <brauner@kernel.org> > Cc: Julian Anastasov <ja@ssi.bg> > Cc: Simon Horman <horms@verge.net.au> > Cc: Pablo Neira Ayuso <pablo@netfilter.org> > Cc: Jozsef Kadlecsik <kadlec@netfilter.org> > Cc: Florian Westphal <fw@strlen.de> > Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com> Looks good to me, thanks! Acked-by: Julian Anastasov <ja@ssi.bg> > --- > net/netfilter/ipvs/ip_vs_ctl.c | 21 +++++++++++++++------ > 1 file changed, 15 insertions(+), 6 deletions(-) > > diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c > index 32be24f0d4e4..c3ba71aa2654 100644 > --- a/net/netfilter/ipvs/ip_vs_ctl.c > +++ b/net/netfilter/ipvs/ip_vs_ctl.c > @@ -4270,6 +4270,7 @@ static int __net_init ip_vs_control_net_init_sysctl(struct netns_ipvs *ipvs) > struct ctl_table *tbl; > int idx, ret; > size_t ctl_table_size = ARRAY_SIZE(vs_vars); > + bool unpriv = net->user_ns != &init_user_ns; > > atomic_set(&ipvs->dropentry, 0); > spin_lock_init(&ipvs->dropentry_lock); > @@ -4284,12 +4285,6 @@ static int __net_init ip_vs_control_net_init_sysctl(struct netns_ipvs *ipvs) > tbl = kmemdup(vs_vars, sizeof(vs_vars), GFP_KERNEL); > if (tbl == NULL) > return -ENOMEM; > - > - /* Don't export sysctls to unprivileged users */ > - if (net->user_ns != &init_user_ns) { > - tbl[0].procname = NULL; > - ctl_table_size = 0; > - } > } else > tbl = vs_vars; > /* Initialize sysctl defaults */ > @@ -4315,10 +4310,17 @@ static int __net_init ip_vs_control_net_init_sysctl(struct netns_ipvs *ipvs) > ipvs->sysctl_sync_ports = 1; > tbl[idx++].data = &ipvs->sysctl_sync_ports; > tbl[idx++].data = &ipvs->sysctl_sync_persist_mode; > + > ipvs->sysctl_sync_qlen_max = nr_free_buffer_pages() / 32; > + if (unpriv) > + tbl[idx].mode = 0444; > tbl[idx++].data = &ipvs->sysctl_sync_qlen_max; > + > ipvs->sysctl_sync_sock_size = 0; > + if (unpriv) > + tbl[idx].mode = 0444; > tbl[idx++].data = &ipvs->sysctl_sync_sock_size; > + > tbl[idx++].data = &ipvs->sysctl_cache_bypass; > tbl[idx++].data = &ipvs->sysctl_expire_nodest_conn; > tbl[idx++].data = &ipvs->sysctl_sloppy_tcp; > @@ -4341,15 +4343,22 @@ static int __net_init ip_vs_control_net_init_sysctl(struct netns_ipvs *ipvs) > tbl[idx++].data = &ipvs->sysctl_conn_reuse_mode; > tbl[idx++].data = &ipvs->sysctl_schedule_icmp; > tbl[idx++].data = &ipvs->sysctl_ignore_tunneled; > + > ipvs->sysctl_run_estimation = 1; > + if (unpriv) > + tbl[idx].mode = 0444; > tbl[idx].extra2 = ipvs; > tbl[idx++].data = &ipvs->sysctl_run_estimation; > > ipvs->est_cpulist_valid = 0; > + if (unpriv) > + tbl[idx].mode = 0444; > tbl[idx].extra2 = ipvs; > tbl[idx++].data = &ipvs->sysctl_est_cpulist; > > ipvs->sysctl_est_nice = IPVS_EST_NICE; > + if (unpriv) > + tbl[idx].mode = 0444; > tbl[idx].extra2 = ipvs; > tbl[idx++].data = &ipvs->sysctl_est_nice; > > -- > 2.34.1 > > Regards -- Julian Anastasov <ja@ssi.bg>
diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c index 32be24f0d4e4..c3ba71aa2654 100644 --- a/net/netfilter/ipvs/ip_vs_ctl.c +++ b/net/netfilter/ipvs/ip_vs_ctl.c @@ -4270,6 +4270,7 @@ static int __net_init ip_vs_control_net_init_sysctl(struct netns_ipvs *ipvs) struct ctl_table *tbl; int idx, ret; size_t ctl_table_size = ARRAY_SIZE(vs_vars); + bool unpriv = net->user_ns != &init_user_ns; atomic_set(&ipvs->dropentry, 0); spin_lock_init(&ipvs->dropentry_lock); @@ -4284,12 +4285,6 @@ static int __net_init ip_vs_control_net_init_sysctl(struct netns_ipvs *ipvs) tbl = kmemdup(vs_vars, sizeof(vs_vars), GFP_KERNEL); if (tbl == NULL) return -ENOMEM; - - /* Don't export sysctls to unprivileged users */ - if (net->user_ns != &init_user_ns) { - tbl[0].procname = NULL; - ctl_table_size = 0; - } } else tbl = vs_vars; /* Initialize sysctl defaults */ @@ -4315,10 +4310,17 @@ static int __net_init ip_vs_control_net_init_sysctl(struct netns_ipvs *ipvs) ipvs->sysctl_sync_ports = 1; tbl[idx++].data = &ipvs->sysctl_sync_ports; tbl[idx++].data = &ipvs->sysctl_sync_persist_mode; + ipvs->sysctl_sync_qlen_max = nr_free_buffer_pages() / 32; + if (unpriv) + tbl[idx].mode = 0444; tbl[idx++].data = &ipvs->sysctl_sync_qlen_max; + ipvs->sysctl_sync_sock_size = 0; + if (unpriv) + tbl[idx].mode = 0444; tbl[idx++].data = &ipvs->sysctl_sync_sock_size; + tbl[idx++].data = &ipvs->sysctl_cache_bypass; tbl[idx++].data = &ipvs->sysctl_expire_nodest_conn; tbl[idx++].data = &ipvs->sysctl_sloppy_tcp; @@ -4341,15 +4343,22 @@ static int __net_init ip_vs_control_net_init_sysctl(struct netns_ipvs *ipvs) tbl[idx++].data = &ipvs->sysctl_conn_reuse_mode; tbl[idx++].data = &ipvs->sysctl_schedule_icmp; tbl[idx++].data = &ipvs->sysctl_ignore_tunneled; + ipvs->sysctl_run_estimation = 1; + if (unpriv) + tbl[idx].mode = 0444; tbl[idx].extra2 = ipvs; tbl[idx++].data = &ipvs->sysctl_run_estimation; ipvs->est_cpulist_valid = 0; + if (unpriv) + tbl[idx].mode = 0444; tbl[idx].extra2 = ipvs; tbl[idx++].data = &ipvs->sysctl_est_cpulist; ipvs->sysctl_est_nice = IPVS_EST_NICE; + if (unpriv) + tbl[idx].mode = 0444; tbl[idx].extra2 = ipvs; tbl[idx++].data = &ipvs->sysctl_est_nice;
Let's make all IPVS sysctls writtable even when network namespace is owned by non-initial user namespace. Let's make a few sysctls to be read-only for non-privileged users: - sync_qlen_max - sync_sock_size - run_estimation - est_cpulist - est_nice I'm trying to be conservative with this to prevent introducing any security issues in there. Maybe, we can allow more sysctls to be writable, but let's do this on-demand and when we see real use-case. This patch is motivated by user request in the LXC project [1]. Having this can help with running some Kubernetes [2] or Docker Swarm [3] workloads inside the system containers. Link: https://github.com/lxc/lxc/issues/4278 [1] Link: https://github.com/kubernetes/kubernetes/blob/b722d017a34b300a2284b890448e5a605f21d01e/pkg/proxy/ipvs/proxier.go#L103 [2] Link: https://github.com/moby/libnetwork/blob/3797618f9a38372e8107d8c06f6ae199e1133ae8/osl/namespace_linux.go#L682 [3] Cc: Stéphane Graber <stgraber@stgraber.org> Cc: Christian Brauner <brauner@kernel.org> Cc: Julian Anastasov <ja@ssi.bg> Cc: Simon Horman <horms@verge.net.au> Cc: Pablo Neira Ayuso <pablo@netfilter.org> Cc: Jozsef Kadlecsik <kadlec@netfilter.org> Cc: Florian Westphal <fw@strlen.de> Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com> --- net/netfilter/ipvs/ip_vs_ctl.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-)