libbpf: Add opts-based bpf_obj_pin() API and add support for path_fd

Add path_fd support for bpf_obj_pin() and bpf_obj_get() operations
(through their opts-based variants). This allows to take advantage of
new kernel-side support for O_PATH-based pin/get location specification.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230523170013.728457-4-andrii@kernel.org

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 128ac72..ed86b37 100644 (file)
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -572,20 +572,30 @@ int bpf_map_update_batch(int fd, const void *keys, const void *values, __u32 *co
                                    (void *)keys, (void *)values, count, opts);
 }
 
-int bpf_obj_pin(int fd, const char *pathname)
+int bpf_obj_pin_opts(int fd, const char *pathname, const struct bpf_obj_pin_opts *opts)
 {
-       const size_t attr_sz = offsetofend(union bpf_attr, file_flags);
+       const size_t attr_sz = offsetofend(union bpf_attr, path_fd);
        union bpf_attr attr;
        int ret;
 
+       if (!OPTS_VALID(opts, bpf_obj_pin_opts))
+               return libbpf_err(-EINVAL);
+
        memset(&attr, 0, attr_sz);
+       attr.path_fd = OPTS_GET(opts, path_fd, 0);
        attr.pathname = ptr_to_u64((void *)pathname);
+       attr.file_flags = OPTS_GET(opts, file_flags, 0);
        attr.bpf_fd = fd;
 
        ret = sys_bpf(BPF_OBJ_PIN, &attr, attr_sz);
        return libbpf_err_errno(ret);
 }
 
+int bpf_obj_pin(int fd, const char *pathname)
+{
+       return bpf_obj_pin_opts(fd, pathname, NULL);
+}
+
 int bpf_obj_get(const char *pathname)
 {
        return bpf_obj_get_opts(pathname, NULL);
@@ -593,7 +603,7 @@ int bpf_obj_get(const char *pathname)
 
 int bpf_obj_get_opts(const char *pathname, const struct bpf_obj_get_opts *opts)
 {
-       const size_t attr_sz = offsetofend(union bpf_attr, file_flags);
+       const size_t attr_sz = offsetofend(union bpf_attr, path_fd);
        union bpf_attr attr;
        int fd;
 
@@ -601,6 +611,7 @@ int bpf_obj_get_opts(const char *pathname, const struct bpf_obj_get_opts *opts)
                return libbpf_err(-EINVAL);
 
        memset(&attr, 0, attr_sz);
+       attr.path_fd = OPTS_GET(opts, path_fd, 0);
        attr.pathname = ptr_to_u64((void *)pathname);
        attr.file_flags = OPTS_GET(opts, file_flags, 0);
 

diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index a2c0913..9aa0ee4 100644 (file)
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -284,16 +284,30 @@ LIBBPF_API int bpf_map_update_batch(int fd, const void *keys, const void *values
                                    __u32 *count,
                                    const struct bpf_map_batch_opts *opts);
 
-struct bpf_obj_get_opts {
+struct bpf_obj_pin_opts {
        size_t sz; /* size of this struct for forward/backward compatibility */
 
        __u32 file_flags;
+       int path_fd;
 
        size_t :0;
 };
-#define bpf_obj_get_opts__last_field file_flags
+#define bpf_obj_pin_opts__last_field path_fd
 
 LIBBPF_API int bpf_obj_pin(int fd, const char *pathname);
+LIBBPF_API int bpf_obj_pin_opts(int fd, const char *pathname,
+                               const struct bpf_obj_pin_opts *opts);
+
+struct bpf_obj_get_opts {
+       size_t sz; /* size of this struct for forward/backward compatibility */
+
+       __u32 file_flags;
+       int path_fd;
+
+       size_t :0;
+};
+#define bpf_obj_get_opts__last_field path_fd
+
 LIBBPF_API int bpf_obj_get(const char *pathname);
 LIBBPF_API int bpf_obj_get_opts(const char *pathname,
                                const struct bpf_obj_get_opts *opts);

diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 9171ac8..7521a2f 100644 (file)
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -393,4 +393,6 @@ LIBBPF_1.2.0 {
 } LIBBPF_1.1.0;
 
 LIBBPF_1.3.0 {
+       global:
+               bpf_obj_pin_opts;
 } LIBBPF_1.2.0;