diff --git a/src/core/bpf/restrict_ifaces/meson.build b/src/core/bpf/restrict_ifaces/meson.build new file mode 100644 index 0000000000..5bf024d42d --- /dev/null +++ b/src/core/bpf/restrict_ifaces/meson.build @@ -0,0 +1,14 @@ +# SPDX-License-Identifier: LGPL-2.1+ + +if conf.get('BPF_FRAMEWORK') == 1 + restrict_ifaces_skel_h = custom_target( + 'restrict-ifaces.skel.h', + input : 'restrict-ifaces.bpf.c', + output : 'restrict-ifaces.skel.h', + command : [build_bpf_skel_py, + '--clang_exec', clang.path(), + '--llvm_strip_exec', llvm_strip.path(), + '--bpftool_exec', bpftool.path(), + '--arch', host_machine.cpu_family(), + '@INPUT@', '@OUTPUT@']) +endif diff --git a/src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.c b/src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.c new file mode 100644 index 0000000000..347a3a8d21 --- /dev/null +++ b/src/core/bpf/restrict_ifaces/restrict-ifaces.bpf.c @@ -0,0 +1,52 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +/* must precede due to integer types + * in bpf helpers signatures. + */ +#include +#include + +const volatile __u8 is_allow_list = 0; + +/* Map containing the network interfaces indexes. + * The interpretation of the map depends on the value of is_allow_list. + */ +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __type(key, __u32); + __type(value, __u8); +} sd_restrictif SEC(".maps"); + +#define DROP 0 +#define PASS 1 + +static inline int restrict_network_interfaces_impl(const struct __sk_buff *sk) { + __u32 zero = 0, ifindex; + __u8 *lookup_result; + + ifindex = sk->ifindex; + lookup_result = bpf_map_lookup_elem(&sd_restrictif, &ifindex); + if (is_allow_list) { + /* allow-list: let the packet pass if iface in the list */ + if (lookup_result) + return PASS; + } else { + /* deny-list: let the packet pass if iface *not* in the list */ + if (!lookup_result) + return PASS; + } + + return DROP; +} + +SEC("cgroup_skb/egress") +int sd_restrictif_e(const struct __sk_buff *sk) { + return restrict_network_interfaces_impl(sk); +} + +SEC("cgroup_skb/ingress") +int sd_restrictif_i(const struct __sk_buff *sk) { + return restrict_network_interfaces_impl(sk); +} + +static const char _license[] SEC("license") = "LGPL-2.1-or-later"; diff --git a/src/core/meson.build b/src/core/meson.build index 1941081972..df773b6675 100644 --- a/src/core/meson.build +++ b/src/core/meson.build @@ -136,6 +136,11 @@ if conf.get('BPF_FRAMEWORK') == 1 libcore_sources += [socket_bind_skel_h] endif +subdir('bpf/restrict_ifaces') +if conf.get('BPF_FRAMEWORK') == 1 + libcore_sources += [restrict_ifaces_skel_h] +endif + load_fragment_gperf_gperf = custom_target( 'load-fragment-gperf.gperf', input : 'load-fragment-gperf.gperf.in',