libbpf: Refactor map creation logic and fix cleanup leak

Factor out map creation and destruction logic to simplify code and especially
error handling. Also fix map FD leak in case of partially successful map
creation during bpf_object load operation.

Fixes: 57a00f41644f ("libbpf: Add auto-pinning of maps when loading BPF objects")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20200429002739.48006-3-andriin@fb.com

1 files changed, 121 insertions, 105 deletions

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 7d10436d7b58..9c845cf4cfcf 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -3493,107 +3493,111 @@ bpf_object__populate_internal_map(struct bpf_object *obj, struct bpf_map *map)
 	return 0;
 }
 
+static void bpf_map__destroy(struct bpf_map *map);
+
+static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map)
+{
+	struct bpf_create_map_attr create_attr;
+	struct bpf_map_def *def = &map->def;
+
+	memset(&create_attr, 0, sizeof(create_attr));
+
+	if (obj->caps.name)
+		create_attr.name = map->name;
+	create_attr.map_ifindex = map->map_ifindex;
+	create_attr.map_type = def->type;
+	create_attr.map_flags = def->map_flags;
+	create_attr.key_size = def->key_size;
+	create_attr.value_size = def->value_size;
+
+	if (def->type == BPF_MAP_TYPE_PERF_EVENT_ARRAY && !def->max_entries) {
+		int nr_cpus;
+
+		nr_cpus = libbpf_num_possible_cpus();
+		if (nr_cpus < 0) {
+			pr_warn("map '%s': failed to determine number of system CPUs: %d\n",
+				map->name, nr_cpus);
+			return nr_cpus;
+		}
+		pr_debug("map '%s': setting size to %d\n", map->name, nr_cpus);
+		create_attr.max_entries = nr_cpus;
+	} else {
+		create_attr.max_entries = def->max_entries;
+	}
+
+	if (bpf_map__is_struct_ops(map))
+		create_attr.btf_vmlinux_value_type_id =
+			map->btf_vmlinux_value_type_id;
+
+	create_attr.btf_fd = 0;
+	create_attr.btf_key_type_id = 0;
+	create_attr.btf_value_type_id = 0;
+	if (obj->btf && !bpf_map_find_btf_info(obj, map)) {
+		create_attr.btf_fd = btf__fd(obj->btf);
+		create_attr.btf_key_type_id = map->btf_key_type_id;
+		create_attr.btf_value_type_id = map->btf_value_type_id;
+	}
+
+	map->fd = bpf_create_map_xattr(&create_attr);
+	if (map->fd < 0 && (create_attr.btf_key_type_id ||
+			    create_attr.btf_value_type_id)) {
+		char *cp, errmsg[STRERR_BUFSIZE];
+		int err = -errno;
+
+		cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
+		pr_warn("Error in bpf_create_map_xattr(%s):%s(%d). Retrying without BTF.\n",
+			map->name, cp, err);
+		create_attr.btf_fd = 0;
+		create_attr.btf_key_type_id = 0;
+		create_attr.btf_value_type_id = 0;
+		map->btf_key_type_id = 0;
+		map->btf_value_type_id = 0;
+		map->fd = bpf_create_map_xattr(&create_attr);
+	}
+
+	if (map->fd < 0)
+		return -errno;
+
+	return 0;
+}
+
 static int
 bpf_object__create_maps(struct bpf_object *obj)
 {
-	struct bpf_create_map_attr create_attr = {};
-	int nr_cpus = 0;
-	unsigned int i;
+	struct bpf_map *map;
+	char *cp, errmsg[STRERR_BUFSIZE];
+	unsigned int i, j;
 	int err;
 
 	for (i = 0; i < obj->nr_maps; i++) {
-		struct bpf_map *map = &obj->maps[i];
-		struct bpf_map_def *def = &map->def;
-		char *cp, errmsg[STRERR_BUFSIZE];
-		int *pfd = &map->fd;
+		map = &obj->maps[i];
 
 		if (map->pin_path) {
 			err = bpf_object__reuse_map(map);
 			if (err) {
-				pr_warn("error reusing pinned map %s\n",
+				pr_warn("map '%s': error reusing pinned map\n",
 					map->name);
-				return err;
+				goto err_out;
 			}
 		}
 
 		if (map->fd >= 0) {
-			pr_debug("skip map create (preset) %s: fd=%d\n",
+			pr_debug("map '%s': skipping creation (preset fd=%d)\n",
 				 map->name, map->fd);
 			continue;
 		}
 
-		if (obj->caps.name)
-			create_attr.name = map->name;
-		create_attr.map_ifindex = map->map_ifindex;
-		create_attr.map_type = def->type;
-		create_attr.map_flags = def->map_flags;
-		create_attr.key_size = def->key_size;
-		create_attr.value_size = def->value_size;
-		if (def->type == BPF_MAP_TYPE_PERF_EVENT_ARRAY &&
-		    !def->max_entries) {
-			if (!nr_cpus)
-				nr_cpus = libbpf_num_possible_cpus();
-			if (nr_cpus < 0) {
-				pr_warn("failed to determine number of system CPUs: %d\n",
-					nr_cpus);
-				err = nr_cpus;
-				goto err_out;
-			}
-			pr_debug("map '%s': setting size to %d\n",
-				 map->name, nr_cpus);
-			create_attr.max_entries = nr_cpus;
-		} else {
-			create_attr.max_entries = def->max_entries;
-		}
-		create_attr.btf_fd = 0;
-		create_attr.btf_key_type_id = 0;
-		create_attr.btf_value_type_id = 0;
-		if (bpf_map_type__is_map_in_map(def->type) &&
-		    map->inner_map_fd >= 0)
-			create_attr.inner_map_fd = map->inner_map_fd;
-		if (bpf_map__is_struct_ops(map))
-			create_attr.btf_vmlinux_value_type_id =
-				map->btf_vmlinux_value_type_id;
-
-		if (obj->btf && !bpf_map_find_btf_info(obj, map)) {
-			create_attr.btf_fd = btf__fd(obj->btf);
-			create_attr.btf_key_type_id = map->btf_key_type_id;
-			create_attr.btf_value_type_id = map->btf_value_type_id;
-		}
-
-		*pfd = bpf_create_map_xattr(&create_attr);
-		if (*pfd < 0 && (create_attr.btf_key_type_id ||
-				 create_attr.btf_value_type_id)) {
-			err = -errno;
-			cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
-			pr_warn("Error in bpf_create_map_xattr(%s):%s(%d). Retrying without BTF.\n",
-				map->name, cp, err);
-			create_attr.btf_fd = 0;
-			create_attr.btf_key_type_id = 0;
-			create_attr.btf_value_type_id = 0;
-			map->btf_key_type_id = 0;
-			map->btf_value_type_id = 0;
-			*pfd = bpf_create_map_xattr(&create_attr);
-		}
-
-		if (*pfd < 0) {
-			size_t j;
+		err = bpf_object__create_map(obj, map);
+		if (err)
+			goto err_out;
 
-			err = -errno;
-err_out:
-			cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
-			pr_warn("failed to create map (name: '%s'): %s(%d)\n",
-				map->name, cp, err);
-			pr_perm_msg(err);
-			for (j = 0; j < i; j++)
-				zclose(obj->maps[j].fd);
-			return err;
-		}
+		pr_debug("map '%s': created successfully, fd=%d\n", map->name,
+			 map->fd);
 
 		if (bpf_map__is_internal(map)) {
 			err = bpf_object__populate_internal_map(obj, map);
 			if (err < 0) {
-				zclose(*pfd);
+				zclose(map->fd);
 				goto err_out;
 			}
 		}
@@ -3601,16 +3605,23 @@ err_out:
 		if (map->pin_path && !map->pinned) {
 			err = bpf_map__pin(map, NULL);
 			if (err) {
-				pr_warn("failed to auto-pin map name '%s' at '%s'\n",
-					map->name, map->pin_path);
-				return err;
+				pr_warn("map '%s': failed to auto-pin at '%s': %d\n",
+					map->name, map->pin_path, err);
+				zclose(map->fd);
+				goto err_out;
 			}
 		}
-
-		pr_debug("created map %s: fd=%d\n", map->name, *pfd);
 	}
 
 	return 0;
+
+err_out:
+	cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
+	pr_warn("map '%s': failed to create: %s(%d)\n", map->name, cp, err);
+	pr_perm_msg(err);
+	for (j = 0; j < i; j++)
+		zclose(obj->maps[j].fd);
+	return err;
 }
 
 static int
@@ -5966,6 +5977,32 @@ int bpf_object__pin(struct bpf_object *obj, const char *path)
 	return 0;
 }
 
+static void bpf_map__destroy(struct bpf_map *map)
+{
+	if (map->clear_priv)
+		map->clear_priv(map, map->priv);
+	map->priv = NULL;
+	map->clear_priv = NULL;
+
+	if (map->mmaped) {
+		munmap(map->mmaped, bpf_map_mmap_sz(map));
+		map->mmaped = NULL;
+	}
+
+	if (map->st_ops) {
+		zfree(&map->st_ops->data);
+		zfree(&map->st_ops->progs);
+		zfree(&map->st_ops->kern_func_off);
+		zfree(&map->st_ops);
+	}
+
+	zfree(&map->name);
+	zfree(&map->pin_path);
+
+	if (map->fd >= 0)
+		zclose(map->fd);
+}
+
 void bpf_object__close(struct bpf_object *obj)
 {
 	size_t i;
@@ -5981,29 +6018,8 @@ void bpf_object__close(struct bpf_object *obj)
 	btf__free(obj->btf);
 	btf_ext__free(obj->btf_ext);
 
-	for (i = 0; i < obj->nr_maps; i++) {
-		struct bpf_map *map = &obj->maps[i];
-
-		if (map->clear_priv)
-			map->clear_priv(map, map->priv);
-		map->priv = NULL;
-		map->clear_priv = NULL;
-
-		if (map->mmaped) {
-			munmap(map->mmaped, bpf_map_mmap_sz(map));
-			map->mmaped = NULL;
-		}
-
-		if (map->st_ops) {
-			zfree(&map->st_ops->data);
-			zfree(&map->st_ops->progs);
-			zfree(&map->st_ops->kern_func_off);
-			zfree(&map->st_ops);
-		}
-
-		zfree(&map->name);
-		zfree(&map->pin_path);
-	}
+	for (i = 0; i < obj->nr_maps; i++)
+		bpf_map__destroy(&obj->maps[i]);
 
 	zfree(&obj->kconfig);
 	zfree(&obj->externs);