diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst index 25e6673a085a..4f649084023a 100644 --- a/Documentation/networking/ip-sysctl.rst +++ b/Documentation/networking/ip-sysctl.rst @@ -1057,6 +1057,19 @@ ip_local_reserved_ports - list of comma separated ranges Default: Empty +ip_local_unbindable_ports - list of comma separated ranges + Specify the ports which are not directly bind()able. + + Usually you would use this to block the use of ports which + are invalid due to something outside of the control of the + kernel. For example a port stolen by the nic for serial + console, remote power management or debugging. + + There's a relatively high chance you will also want to list + these ports in 'ip_local_reserved_ports' to prevent autobinding. + + Default: Empty + ip_unprivileged_port_start - INTEGER This is a per-namespace sysctl. It defines the first unprivileged port in the network namespace. Privileged ports diff --git a/include/net/ip.h b/include/net/ip.h index 2d6b985d11cc..ace6739f59c6 100644 --- a/include/net/ip.h +++ b/include/net/ip.h @@ -343,6 +343,13 @@ static inline bool inet_is_local_reserved_port(struct net *net, unsigned short p return test_bit(port, net->ipv4.sysctl_local_reserved_ports); } +static inline bool inet_is_local_unbindable_port(struct net *net, unsigned short port) +{ + if (!net->ipv4.sysctl_local_unbindable_ports) + return false; + return test_bit(port, net->ipv4.sysctl_local_unbindable_ports); +} + static inline bool sysctl_dev_name_is_allowed(const char *name) { return strcmp(name, "default") != 0 && strcmp(name, "all") != 0; @@ -359,6 +366,11 @@ static inline bool inet_is_local_reserved_port(struct net *net, unsigned short p return false; } +static inline bool inet_is_local_unbindable_port(struct net *net, unsigned short port) +{ + return false; +} + static inline bool inet_port_requires_bind_service(struct net *net, unsigned short port) { return port < PROT_SOCK; diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h index 8e4fcac4df72..175206956080 100644 --- a/include/net/netns/ipv4.h +++ b/include/net/netns/ipv4.h @@ -203,6 +203,7 @@ struct netns_ipv4 { #ifdef CONFIG_SYSCTL unsigned long *sysctl_local_reserved_ports; + unsigned long *sysctl_local_unbindable_ports; int sysctl_ip_prot_sock; #endif diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c index b7260c8cef2e..b2ee0be107e7 100644 --- a/net/ipv4/af_inet.c +++ b/net/ipv4/af_inet.c @@ -498,6 +498,10 @@ int __inet_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len, goto out; snum = ntohs(addr->sin_port); + err = -EPERM; + if (snum && inet_is_local_unbindable_port(net, snum)) + goto out; + err = -EACCES; if (snum && inet_port_requires_bind_service(net, snum) && !ns_capable(net->user_ns, CAP_NET_BIND_SERVICE)) diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c index 3e5f4f2e705e..4094fb085cd9 100644 --- a/net/ipv4/sysctl_net_ipv4.c +++ b/net/ipv4/sysctl_net_ipv4.c @@ -726,6 +726,13 @@ static struct ctl_table ipv4_net_table[] = { .mode = 0644, .proc_handler = proc_do_large_bitmap, }, + { + .procname = "ip_local_unbindable_ports", + .data = &init_net.ipv4.sysctl_local_unbindable_ports, + .maxlen = 65536, + .mode = 0644, + .proc_handler = proc_do_large_bitmap, + }, { .procname = "ip_no_pmtu_disc", .data = &init_net.ipv4.sysctl_ip_no_pmtu_disc, @@ -1380,11 +1387,17 @@ static __net_init int ipv4_sysctl_init_net(struct net *net) net->ipv4.sysctl_local_reserved_ports = kzalloc(65536 / 8, GFP_KERNEL); if (!net->ipv4.sysctl_local_reserved_ports) - goto err_ports; + goto err_reserved_ports; + + net->ipv4.sysctl_local_unbindable_ports = kzalloc(65536 / 8, GFP_KERNEL); + if (!net->ipv4.sysctl_local_unbindable_ports) + goto err_unbindable_ports; return 0; -err_ports: +err_unbindable_ports: + kfree(net->ipv4.sysctl_local_reserved_ports); +err_reserved_ports: unregister_net_sysctl_table(net->ipv4.ipv4_hdr); err_reg: if (!net_eq(net, &init_net)) @@ -1397,6 +1410,7 @@ static __net_exit void ipv4_sysctl_exit_net(struct net *net) { struct ctl_table *table; + kfree(net->ipv4.sysctl_local_unbindable_ports); kfree(net->ipv4.sysctl_local_reserved_ports); table = net->ipv4.ipv4_hdr->ctl_table_arg; unregister_net_sysctl_table(net->ipv4.ipv4_hdr); diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c index e648fbebb167..c6db41b5063f 100644 --- a/net/ipv6/af_inet6.c +++ b/net/ipv6/af_inet6.c @@ -295,6 +295,8 @@ static int __inet6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len, return -EINVAL; snum = ntohs(addr->sin6_port); + if (snum && inet_is_local_unbindable_port(net, snum)) + return -EPERM; if (snum && inet_port_requires_bind_service(net, snum) && !ns_capable(net->user_ns, CAP_NET_BIND_SERVICE)) return -EACCES; diff --git a/net/sctp/socket.c b/net/sctp/socket.c index 53d0a4161df3..3606aae76f34 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -399,6 +399,9 @@ static int sctp_do_bind(struct sock *sk, union sctp_addr *addr, int len) } } + if (snum && inet_is_local_unbindable_port(net, snum)) + return -EPERM; + if (snum && inet_port_requires_bind_service(net, snum) && !ns_capable(net->user_ns, CAP_NET_BIND_SERVICE)) return -EACCES; @@ -1065,6 +1068,8 @@ static int sctp_connect_new_asoc(struct sctp_endpoint *ep, if (sctp_autobind(sk)) return -EAGAIN; } else { + if (inet_is_local_unbindable_port(net, ep->base.bind_addr.port)) + return -EPERM; if (inet_port_requires_bind_service(net, ep->base.bind_addr.port) && !ns_capable(net->user_ns, CAP_NET_BIND_SERVICE)) return -EACCES;