[PATCH v5 bpf-next 09/13] libbpf: add bpf_token_create() API

[Andrii Nakryiko <andrii@kernel.org>]

Add low-level wrapper API for BPF_TOKEN_CREATE command in bpf() syscall.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/lib/bpf/bpf.c      | 19 +++++++++++++++++++
 tools/lib/bpf/bpf.h      | 28 ++++++++++++++++++++++++++++
 tools/lib/bpf/libbpf.map |  1 +
 3 files changed, 48 insertions(+)

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index b0f1913763a3..593ff9ea120d 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -1271,3 +1271,22 @@ int bpf_prog_bind_map(int prog_fd, int map_fd,
 	ret = sys_bpf(BPF_PROG_BIND_MAP, &attr, attr_sz);
 	return libbpf_err_errno(ret);
 }
+
+int bpf_token_create(int bpffs_path_fd, const char *bpffs_pathname,
+		     struct bpf_token_create_opts *opts)
+{
+	const size_t attr_sz = offsetofend(union bpf_attr, token_create);
+	union bpf_attr attr;
+	int fd;
+
+	if (!OPTS_VALID(opts, bpf_token_create_opts))
+		return libbpf_err(-EINVAL);
+
+	memset(&attr, 0, attr_sz);
+	attr.token_create.bpffs_path_fd = bpffs_path_fd;
+	attr.token_create.bpffs_pathname = ptr_to_u64(bpffs_pathname);
+	attr.token_create.flags = OPTS_GET(opts, flags, 0);
+
+	fd = sys_bpf_fd(BPF_TOKEN_CREATE, &attr, attr_sz);
+	return libbpf_err_errno(fd);
+}
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 74c2887cfd24..a5ddb0393fee 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -635,6 +635,34 @@ struct bpf_test_run_opts {
 LIBBPF_API int bpf_prog_test_run_opts(int prog_fd,
 				      struct bpf_test_run_opts *opts);
 
+struct bpf_token_create_opts {
+	size_t sz; /* size of this struct for forward/backward compatibility */
+	__u32 flags;
+	size_t :0;
+};
+#define bpf_token_create_opts__last_field flags
+
+/**
+ * @brief **bpf_token_create()** creates a new instance of BPF token derived
+ * from specified BPF FS mount point.
+ *
+ * BPF token created with this API can be passed to bpf() syscall for
+ * commands like BPF_PROG_LOAD, BPF_MAP_CREATE, etc.
+ *
+ * @param bpffs_path_fd O_PATH FD (see man 2 openat() for semantics) specifying,
+ * in combination with *bpffs_pathname*, BPF FS mount from which to derive
+ * a BPF token instance.
+ * @param pin_pathname absolute or relative path specifying,in combination
+ * with *bpffs_pathname*, BPF FS mount from which to derive a BPF token
+ * instance.
+ * @param opts optional BPF token creation options, can be NULL
+ *
+ * @return BPF token FD > 0, on success; negative error code, otherwise (errno
+ * is also set to the error code)
+ */
+LIBBPF_API int bpf_token_create(int bpffs_path_fd, const char *bpffs_pathname,
+				struct bpf_token_create_opts *opts);
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 57712321490f..c45c28a5e14c 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -400,4 +400,5 @@ LIBBPF_1.3.0 {
 		bpf_program__attach_netfilter;
 		bpf_program__attach_tcx;
 		bpf_program__attach_uprobe_multi;
+		bpf_token_create;
 } LIBBPF_1.2.0;
-- 
2.34.1