core: rename socket-bind.[ch] → bpf-socket-bind.[ch]

The other BPF infra has a file name prefix of "bpf-" hence do so here
too.

1 files changed, 252 insertions, 0 deletions

diff --git a/src/core/bpf-socket-bind.c b/src/core/bpf-socket-bind.c
new file mode 100644
index 0000000000..0ef3b6e568
--- /dev/null
+++ b/src/core/bpf-socket-bind.c
@@ -0,0 +1,252 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#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/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) {
+                struct socket_bind_rule val = {
+                        .address_family = (uint32_t) item->address_family,
+                        .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;
+        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_full_errno(u, u ? LOG_ERR : LOG_WARNING, 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_full_errno(u, u ? LOG_ERR : LOG_WARNING, 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_full_errno(u, u ? LOG_ERR : LOG_DEBUG, SYNTHETIC_ERRNO(ENOMEM),
+                                           "Failed to open BPF object");
+
+        if (sym_bpf_map__resize(obj->maps.sd_bind_allow, MAX(allow_count, 1u)) != 0)
+                return log_unit_full_errno(u, u ? LOG_ERR : LOG_WARNING, errno,
+                                           "Failed to resize BPF map '%s': %m", sym_bpf_map__name(obj->maps.sd_bind_allow));
+
+        if (sym_bpf_map__resize(obj->maps.sd_bind_deny, MAX(deny_count, 1u)) != 0)
+                return log_unit_full_errno(u, u ? LOG_ERR : LOG_WARNING, errno,
+                                           "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,
+                                           "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,
+                                           "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,
+                                           "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;
+
+        r = cg_unified_controller(SYSTEMD_CGROUP_CONTROLLER);
+        if (r < 0)
+                return log_debug_errno(r, "Can't determine whether the unified hierarchy is used: %m");
+        if (r == 0) {
+                log_debug("Not running with unified cgroup hierarchy, BPF is not supported");
+                return false;
+        }
+
+        if (dlopen_bpf() < 0)
+                return false;
+
+        if (!sym_bpf_probe_prog_type(BPF_PROG_TYPE_CGROUP_SOCK_ADDR, /*ifindex=*/0)) {
+                log_debug("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 based socket_bind is not supported: %m");
+                return false;
+        }
+
+        return can_link_bpf_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, "Failed to put socket-bind BPF link 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 = -1;
+        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, "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: %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, "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, "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 = serialize_bpf_link(f, fds, "ipv4-socket-bind-bpf-link", u->ipv4_socket_bind_link);
+        if (r < 0)
+                return r;
+
+        return serialize_bpf_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), "Failed to install socket bind: BPF framework is not supported");
+}
+
+int bpf_serialize_socket_bind(Unit *u, FILE *f, FDSet *fds) {
+        return 0;
+}
+#endif