1 files changed, 309 insertions, 0 deletions
diff --git a/src/bpfswitch/usrc/libbpf_helpers.c b/src/bpfswitch/usrc/libbpf_helpers.c
new file mode 100644
index 00000000..522f5586
--- /dev/null
+++ b/src/bpfswitch/usrc/libbpf_helpers.c
@@ -0,0 +1,309 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * convenience wrappers around libbpf functions
+ *
+ * Copyright (c) 2019-2021 David Ahern <dsahern@gmail.com>
+ */
+
+#include <linux/if_link.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <limits.h>
+#include <unistd.h>
+#include <bpf/bpf.h>
+#include <bpf/libbpf.h>
+#include <errno.h>
+
+#include "libbpf_helpers.h"
+
+enum bpf_obj_type {
+	BPF_OBJ_UNKNOWN,
+	BPF_OBJ_PROG,
+	BPF_OBJ_MAP,
+	BPF_OBJ_LINK,
+	BPF_OBJ_BTF,
+};
+
+int load_obj_file(struct bpf_prog_load_attr *attr,
+		  struct bpf_object **obj,
+		  const char *objfile, bool user_set)
+{
+	static char *expected_paths[] = {
+		"bin",
+		"ksrc/obj",	/* path in git tree */
+		"bpf-obj",
+		".",		/* cwd */
+		NULL,
+	};
+	char path[PATH_MAX];
+	int prog_fd, i = 0;
+
+	if (user_set) {
+		attr->file = objfile;
+		return bpf_prog_load_xattr(attr, obj, &prog_fd);
+	}
+
+	attr->file = path;
+	while (expected_paths[i]) {
+		struct stat sbuf;
+
+		snprintf(path, sizeof(path), "%s/%s",
+			 expected_paths[i], objfile);
+
+		if (stat(path, &sbuf) == 0) {
+			if (!bpf_prog_load_xattr(attr, obj, &prog_fd))
+				return 0;
+
+			if (errno != ENOENT)
+				break;
+		}
+		++i;
+	}
+
+	fprintf(stderr, "Failed to find object file; nothing to load\n");
+	return 1;
+}
+
+int bpf_map_get_fd_by_name(const char *name)
+{
+	struct bpf_map_info info = {};
+	__u32 len = sizeof(info);
+	__u32 id = 0;
+	int err, fd;
+
+	while (1) {
+		err = bpf_map_get_next_id(id, &id);
+		if (err)
+			break;
+
+		fd = bpf_map_get_fd_by_id(id);
+		if (fd < 0)
+			continue;
+
+		err = bpf_obj_get_info_by_fd(fd, &info, &len);
+		if (!err && strcmp(info.name, name) == 0)
+			return fd;
+
+		close(fd);
+	}
+
+	return -1;
+}
+
+/* from bpftool */
+static int get_fd_type(int fd)
+{
+	char path[PATH_MAX];
+	char buf[512];
+	ssize_t n;
+
+	snprintf(path, sizeof(path), "/proc/self/fd/%d", fd);
+
+	n = readlink(path, buf, sizeof(buf));
+	if (n < 0) {
+		fprintf(stderr, "can't read link type: %s\n", strerror(errno));
+		return -1;
+	}
+	if (n == sizeof(path)) {
+		fprintf(stderr, "can't read link type: path too long!\n");
+		return -1;
+	}
+
+	if (strstr(buf, "bpf-map"))
+		return BPF_OBJ_MAP;
+
+	if (strstr(buf, "bpf-prog"))
+		return BPF_OBJ_PROG;
+
+	if (strstr(buf, "bpf-link"))
+		return BPF_OBJ_LINK;
+
+	return BPF_OBJ_UNKNOWN;
+}
+
+int bpf_map_get_fd_by_path(const char *path)
+{
+	enum bpf_obj_type objtype;
+	int fd;
+
+	fd = bpf_obj_get(path);
+	if (fd < 0) {
+		fprintf(stderr, "Failed to get bpf object (%s): %s\n",
+			path, strerror(errno));
+		return -1;
+	}
+
+	objtype = get_fd_type(fd);
+	if (objtype != BPF_OBJ_MAP) {
+		fprintf(stderr, "Path is not to a BPF map\n");
+		close(fd);
+		return -1;
+	}
+
+	return fd;
+}
+
+int bpf_map_get_fd(__u32 id, const char *path, const char *name,
+		   const char *desc)
+{
+	int fd = -1;
+
+	if (id) {
+		fd = bpf_map_get_fd_by_id(id);
+		if (fd < 0 && errno != ENOENT) {
+			fprintf(stderr,
+				"Failed to get fd for %s by id: %s: %d\n",
+				desc, strerror(errno), errno);
+			return -1;
+		}
+	} else if (path) {
+		fd = bpf_map_get_fd_by_path(path);
+		if (fd < 0) {
+			fprintf(stderr,
+				"Failed to get fd for %s by path: %s: %d\n",
+				desc, strerror(errno), errno);
+			return -1;
+		}
+	} else if (name) {
+		fd = bpf_map_get_fd_by_name(name);
+		if (fd < 0 && errno != ENOENT) {
+			fprintf(stderr,
+				"Failed to get fd for %s by expected name: %s: %d\n",
+				desc, strerror(errno), errno);
+			return -1;
+		}
+	}
+
+	return fd;
+}
+
+int bpf_prog_get_fd_by_path(const char *path)
+{
+	enum bpf_obj_type objtype;
+	int fd;
+
+	fd = bpf_obj_get(path);
+	if (fd < 0) {
+		fprintf(stderr, "Failed to get bpf object (%s): %s\n",
+			path, strerror(errno));
+		return -1;
+	}
+
+	objtype = get_fd_type(fd);
+	if (objtype != BPF_OBJ_PROG) {
+		fprintf(stderr, "Path is not to a BPF program\n");
+		close(fd);
+		return -1;
+	}
+
+	return fd;
+}
+
+int bpf_prog_get_fd_by_name(const char *name)
+{
+	struct bpf_prog_info info = {};
+	__u32 len = sizeof(info);
+	__u32 id = 0;
+	int err, fd;
+
+	while (1) {
+		err = bpf_prog_get_next_id(id, &id);
+		if (err)
+			break;
+
+		fd = bpf_prog_get_fd_by_id(id);
+		if (fd < 0)
+			continue;
+
+		err = bpf_obj_get_info_by_fd(fd, &info, &len);
+		if (!err && strcmp(info.name, name) == 0)
+			return fd;
+
+		close(fd);
+	}
+
+	return -1;
+}
+
+int bpf_prog_get_fd(__u32 id, const char *path, const char *name,
+		    const char *desc)
+{
+	int fd = -1;
+
+	if (id) {
+		fd = bpf_prog_get_fd_by_id(id);
+		if (fd < 0 && errno != ENOENT) {
+			fprintf(stderr,
+				"Failed to get fd for %s by id: %s: %d\n",
+				desc, strerror(errno), errno);
+			return -1;
+		}
+	} else if (path) {
+		fd = bpf_prog_get_fd_by_path(path);
+		if (fd < 0) {
+			fprintf(stderr,
+				"Failed to get fd for %s by path: %s: %d\n",
+				desc, strerror(errno), errno);
+			return -1;
+		}
+	} else if (name) {
+		fd = bpf_prog_get_fd_by_name(name);
+		if (fd < 0 && errno != ENOENT) {
+			fprintf(stderr,
+				"Failed to get fd for %s by expected name: %s: %d\n",
+				desc, strerror(errno), errno);
+			return -1;
+		}
+	}
+
+	return fd;
+}
+
+int attach_to_dev_generic(int idx, int prog_fd, const char *dev)
+{
+	int err;
+
+	err = bpf_set_link_xdp_fd(idx, prog_fd, XDP_FLAGS_SKB_MODE);
+	if (err < 0) {
+		printf("ERROR: failed to attach program to %s\n", dev);
+		return err;
+	}
+
+	return 0;
+}
+
+int detach_from_dev_generic(int idx, const char *dev)
+{
+	int err;
+
+	err = bpf_set_link_xdp_fd(idx, -1, XDP_FLAGS_SKB_MODE);
+	if (err < 0)
+		printf("ERROR: failed to detach program from %s\n", dev);
+
+	return 0;
+}
+
+
+int attach_to_dev(int idx, int prog_fd, const char *dev)
+{
+	int err;
+
+	err = bpf_set_link_xdp_fd(idx, prog_fd, XDP_FLAGS_DRV_MODE);
+	if (err < 0) {
+		printf("ERROR: failed to attach program to %s\n", dev);
+		return err;
+	}
+
+	return 0;
+}
+
+int detach_from_dev(int idx, const char *dev)
+{
+	int err;
+
+	err = bpf_set_link_xdp_fd(idx, -1, 0);
+	if (err < 0)
+		printf("ERROR: failed to detach program from %s\n", dev);
+
+	return 0;
+}