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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#if BPF_FRAMEWORK
#include <bpf/bpf.h>
#endif
#include "fd-util.h"
#include "bpf-socket-bind.h"
#if BPF_FRAMEWORK
/* libbpf, clang, llvm and bpftool compile time dependencies are satisfied */
#include "bpf-dlopen.h"
#include "bpf-link.h"
#include "bpf-util.h"
#include "bpf/socket_bind/socket-bind-api.bpf.h"
#include "bpf/socket_bind/socket-bind-skel.h"
static struct socket_bind_bpf *socket_bind_bpf_free(struct socket_bind_bpf *obj) {
/* socket_bind_bpf__destroy handles object == NULL case */
(void) socket_bind_bpf__destroy(obj);
return NULL;
}
DEFINE_TRIVIAL_CLEANUP_FUNC(struct socket_bind_bpf *, socket_bind_bpf_free);
static int update_rules_map(
int map_fd,
CGroupSocketBindItem *head) {
uint32_t i = 0;
assert(map_fd >= 0);
LIST_FOREACH(socket_bind_items, item, head) {
struct socket_bind_rule val = {
.address_family = (uint32_t) item->address_family,
.protocol = item->ip_protocol,
.nr_ports = item->nr_ports,
.port_min = item->port_min,
};
uint32_t key = i++;
if (sym_bpf_map_update_elem(map_fd, &key, &val, BPF_ANY) != 0)
return -errno;
}
return 0;
}
static int prepare_socket_bind_bpf(
Unit *u,
CGroupSocketBindItem *allow,
CGroupSocketBindItem *deny,
struct socket_bind_bpf **ret_obj) {
_cleanup_(socket_bind_bpf_freep) struct socket_bind_bpf *obj = NULL;
size_t allow_count = 0, deny_count = 0;
int allow_map_fd, deny_map_fd, r;
assert(ret_obj);
LIST_FOREACH(socket_bind_items, item, allow)
allow_count++;
LIST_FOREACH(socket_bind_items, item, deny)
deny_count++;
if (allow_count > SOCKET_BIND_MAX_RULES)
return log_unit_full_errno(u, u ? LOG_ERR : LOG_WARNING, SYNTHETIC_ERRNO(EINVAL),
"bpf-socket-bind: Maximum number of socket bind rules=%i is exceeded", SOCKET_BIND_MAX_RULES);
if (deny_count > SOCKET_BIND_MAX_RULES)
return log_unit_full_errno(u, u ? LOG_ERR : LOG_WARNING, SYNTHETIC_ERRNO(EINVAL),
"bpf-socket-bind: Maximum number of socket bind rules=%i is exceeded", SOCKET_BIND_MAX_RULES);
obj = socket_bind_bpf__open();
if (!obj)
return log_unit_full_errno(u, u ? LOG_ERR : LOG_DEBUG, errno, "bpf-socket-bind: Failed to open BPF object: %m");
if (sym_bpf_map__set_max_entries(obj->maps.sd_bind_allow, MAX(allow_count, 1u)) != 0)
return log_unit_full_errno(u, u ? LOG_ERR : LOG_WARNING, errno,
"bpf-socket-bind: Failed to resize BPF map '%s': %m", sym_bpf_map__name(obj->maps.sd_bind_allow));
if (sym_bpf_map__set_max_entries(obj->maps.sd_bind_deny, MAX(deny_count, 1u)) != 0)
return log_unit_full_errno(u, u ? LOG_ERR : LOG_WARNING, errno,
"bpf-socket-bind: Failed to resize BPF map '%s': %m", sym_bpf_map__name(obj->maps.sd_bind_deny));
if (socket_bind_bpf__load(obj) != 0)
return log_unit_full_errno(u, u ? LOG_ERR : LOG_DEBUG, errno,
"bpf-socket-bind: Failed to load BPF object: %m");
allow_map_fd = sym_bpf_map__fd(obj->maps.sd_bind_allow);
assert(allow_map_fd >= 0);
r = update_rules_map(allow_map_fd, allow);
if (r < 0)
return log_unit_full_errno(u, u ? LOG_ERR : LOG_WARNING, r,
"bpf-socket-bind: Failed to put socket bind allow rules into BPF map '%s'",
sym_bpf_map__name(obj->maps.sd_bind_allow));
deny_map_fd = sym_bpf_map__fd(obj->maps.sd_bind_deny);
assert(deny_map_fd >= 0);
r = update_rules_map(deny_map_fd, deny);
if (r < 0)
return log_unit_full_errno(u, u ? LOG_ERR : LOG_WARNING, r,
"bpf-socket-bind: Failed to put socket bind deny rules into BPF map '%s'",
sym_bpf_map__name(obj->maps.sd_bind_deny));
*ret_obj = TAKE_PTR(obj);
return 0;
}
int bpf_socket_bind_supported(void) {
_cleanup_(socket_bind_bpf_freep) struct socket_bind_bpf *obj = NULL;
int r;
if (!cgroup_bpf_supported())
return false;
if (!compat_libbpf_probe_bpf_prog_type(BPF_PROG_TYPE_CGROUP_SOCK_ADDR, /*opts=*/NULL)) {
log_debug("bpf-socket-bind: BPF program type cgroup_sock_addr is not supported");
return false;
}
r = prepare_socket_bind_bpf(/*unit=*/NULL, /*allow_rules=*/NULL, /*deny_rules=*/NULL, &obj);
if (r < 0) {
log_debug_errno(r, "bpf-socket-bind: socket bind filtering is not supported: %m");
return false;
}
return bpf_can_link_program(obj->progs.sd_bind4);
}
int bpf_socket_bind_add_initial_link_fd(Unit *u, int fd) {
int r;
assert(u);
if (!u->initial_socket_bind_link_fds) {
u->initial_socket_bind_link_fds = fdset_new();
if (!u->initial_socket_bind_link_fds)
return log_oom();
}
r = fdset_put(u->initial_socket_bind_link_fds, fd);
if (r < 0)
return log_unit_error_errno(u, r, "bpf-socket-bind: Failed to put BPF fd %d to initial fdset", fd);
return 0;
}
static int socket_bind_install_impl(Unit *u) {
_cleanup_(bpf_link_freep) struct bpf_link *ipv4 = NULL, *ipv6 = NULL;
_cleanup_(socket_bind_bpf_freep) struct socket_bind_bpf *obj = NULL;
_cleanup_free_ char *cgroup_path = NULL;
_cleanup_close_ int cgroup_fd = -EBADF;
CGroupContext *cc;
int r;
assert(u);
cc = unit_get_cgroup_context(u);
if (!cc)
return 0;
r = cg_get_path(SYSTEMD_CGROUP_CONTROLLER, u->cgroup_path, NULL, &cgroup_path);
if (r < 0)
return log_unit_error_errno(u, r, "bpf-socket-bind: Failed to get cgroup path: %m");
if (!cc->socket_bind_allow && !cc->socket_bind_deny)
return 0;
r = prepare_socket_bind_bpf(u, cc->socket_bind_allow, cc->socket_bind_deny, &obj);
if (r < 0)
return log_unit_error_errno(u, r, "bpf-socket-bind: Failed to load BPF object: %m");
cgroup_fd = open(cgroup_path, O_RDONLY | O_CLOEXEC, 0);
if (cgroup_fd < 0)
return log_unit_error_errno(u, errno, "bpf-socket-bind: Failed to open cgroup %s for reading: %m", cgroup_path);
ipv4 = sym_bpf_program__attach_cgroup(obj->progs.sd_bind4, cgroup_fd);
r = sym_libbpf_get_error(ipv4);
if (r != 0)
return log_unit_error_errno(u, r, "bpf-socket-bind: Failed to link '%s' cgroup-bpf program: %m",
sym_bpf_program__name(obj->progs.sd_bind4));
ipv6 = sym_bpf_program__attach_cgroup(obj->progs.sd_bind6, cgroup_fd);
r = sym_libbpf_get_error(ipv6);
if (r != 0)
return log_unit_error_errno(u, r, "bpf-socket-bind: Failed to link '%s' cgroup-bpf program: %m",
sym_bpf_program__name(obj->progs.sd_bind6));
u->ipv4_socket_bind_link = TAKE_PTR(ipv4);
u->ipv6_socket_bind_link = TAKE_PTR(ipv6);
return 0;
}
int bpf_socket_bind_install(Unit *u) {
int r;
assert(u);
r = socket_bind_install_impl(u);
if (r == -ENOMEM)
return r;
fdset_close(u->initial_socket_bind_link_fds);
return r;
}
int bpf_serialize_socket_bind(Unit *u, FILE *f, FDSet *fds) {
int r;
assert(u);
r = bpf_serialize_link(f, fds, "ipv4-socket-bind-bpf-link", u->ipv4_socket_bind_link);
if (r < 0)
return r;
return bpf_serialize_link(f, fds, "ipv6-socket-bind-bpf-link", u->ipv6_socket_bind_link);
}
#else /* ! BPF_FRAMEWORK */
int bpf_socket_bind_supported(void) {
return false;
}
int bpf_socket_bind_add_initial_link_fd(Unit *u, int fd) {
return 0;
}
int bpf_socket_bind_install(Unit *u) {
return log_unit_debug_errno(u, SYNTHETIC_ERRNO(EOPNOTSUPP),
"bpf-socket-bind: Failed to install; BPF framework is not supported");
}
int bpf_serialize_socket_bind(Unit *u, FILE *f, FDSet *fds) {
return 0;
}
#endif
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