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/* SPDX-License-Identifier: LGPL-2.1+ */
#if BPF_FRAMEWORK
#include <bpf/bpf.h>
#endif
#include "fd-util.h"
#include "socket-bind.h"
#if BPF_FRAMEWORK
/* libbpf, clang, llvm and bpftool compile time dependencies are satisfied */
#include "bpf-link.h"
#include "bpf/socket_bind/socket-bind.skel.h"
#include "bpf/socket_bind/socket-bind-api.bpf.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) {
CGroupSocketBindItem *item;
uint32_t i = 0;
assert(map_fd >= 0);
LIST_FOREACH(socket_bind_items, item, head) {
const uint32_t key = i++;
struct socket_bind_rule val = {
.address_family = (uint32_t) item->address_family,
.nr_ports = item->nr_ports,
.port_min = item->port_min,
};
if (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 = 0;
uint32_t allow_count = 0, deny_count = 0;
int allow_map_fd, deny_map_fd, r;
CGroupSocketBindItem *item;
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_error_errno(u, SYNTHETIC_ERRNO(EINVAL),
"Maximum number of socket bind rules=%u is exceeded", SOCKET_BIND_MAX_RULES);
if (deny_count > SOCKET_BIND_MAX_RULES)
return log_unit_error_errno(u, SYNTHETIC_ERRNO(EINVAL),
"Maximum number of socket bind rules=%u is exceeded", SOCKET_BIND_MAX_RULES);
obj = socket_bind_bpf__open();
if (!obj)
return log_unit_error_errno(u, SYNTHETIC_ERRNO(ENOMEM), "Failed to open BPF object");
if (bpf_map__resize(obj->maps.sd_bind_allow, MAX(allow_count, 1u)) != 0)
return log_unit_error_errno(u, errno,
"Failed to resize BPF map '%s': %m", bpf_map__name(obj->maps.sd_bind_allow));
if (bpf_map__resize(obj->maps.sd_bind_deny, MAX(deny_count, 1u)) != 0)
return log_unit_error_errno(u, errno,
"Failed to resize BPF map '%s': %m", bpf_map__name(obj->maps.sd_bind_deny));
if (socket_bind_bpf__load(obj) != 0)
return log_unit_error_errno(u, errno, "Failed to load BPF object");
allow_map_fd = 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_error_errno(
u, r, "Failed to put socket bind allow rules into BPF map '%s'",
bpf_map__name(obj->maps.sd_bind_allow));
deny_map_fd = 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_error_errno(
u, r, "Failed to put socket bind deny rules into BPF map '%s'",
bpf_map__name(obj->maps.sd_bind_deny));
*ret_obj = TAKE_PTR(obj);
return 0;
}
int socket_bind_supported(void) {
_cleanup_(socket_bind_bpf_freep) struct socket_bind_bpf *obj = NULL;
int r = cg_unified_controller(SYSTEMD_CGROUP_CONTROLLER);
if (r < 0)
return log_error_errno(r, "Can't determine whether the unified hierarchy is used: %m");
if (r == 0) {
log_debug_errno(SYNTHETIC_ERRNO(EOPNOTSUPP),
"Not running with unified cgroup hierarchy, BPF is not supported");
return 0;
}
if (!bpf_probe_prog_type(BPF_PROG_TYPE_CGROUP_SOCK_ADDR, /*ifindex=*/0)) {
log_debug_errno(SYNTHETIC_ERRNO(EOPNOTSUPP),
"BPF program type cgroup_sock_addr is not supported");
return 0;
}
r = prepare_socket_bind_bpf(/*unit=*/NULL, /*allow_rules=*/NULL, /*deny_rules=*/NULL, &obj);
if (r < 0) {
log_debug_errno(r, "BPF based socket_bind is not supported: %m");
return 0;
}
return can_link_bpf_program(obj->progs.sd_bind4);
}
int socket_bind_install(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 = -1;
CGroupContext *cc;
int r;
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, "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, "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, "Failed to open cgroup=%s for reading", cgroup_path);
ipv4 = bpf_program__attach_cgroup(obj->progs.sd_bind4, cgroup_fd);
r = libbpf_get_error(ipv4);
if (r != 0)
return log_unit_error_errno(u, r, "Failed to link '%s' cgroup-bpf program",
bpf_program__name(obj->progs.sd_bind4));
ipv6 = bpf_program__attach_cgroup(obj->progs.sd_bind6, cgroup_fd);
r = libbpf_get_error(ipv6);
if (r != 0)
return log_unit_error_errno(u, r, "Failed to link '%s' cgroup-bpf program",
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;
}
#else /* ! BPF_FRAMEWORK */
int socket_bind_supported(void) {
return 0;
}
int socket_bind_install(Unit *u) {
log_unit_debug(u, "Failed to install socket bind: BPF framework is not supported");
return 0;
}
#endif
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