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-rw-r--r--src/core/bpf-socket-bind.c244
1 files changed, 244 insertions, 0 deletions
diff --git a/src/core/bpf-socket-bind.c b/src/core/bpf-socket-bind.c
new file mode 100644
index 0000000..9f290ab
--- /dev/null
+++ b/src/core/bpf-socket-bind.c
@@ -0,0 +1,244 @@
+/* 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
generated by cgit v1.2.3 (git 2.39.1) at 2024-05-18 19:30:39 +0000