[PATCH bpf-next 2/3] libbpf: add opts-based bpf_obj_pin() API and add support for path_fd

Andrii Nakryiko
2023-05-16T00:14:06Z

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>
---
tools/lib/bpf/bpf.c | 16 +++++++++++++---
tools/lib/bpf/bpf.h | 17 +++++++++++++++--
tools/lib/bpf/libbpf.map | 1 +
3 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 128ac723c4ea..35cdc0777d79 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -572,13 +572,17 @@ 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.bpf_fd = fd;

@@ -586,6 +590,11 @@ int bpf_obj_pin(int fd, const char *pathname)
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 +602,7 @@ 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 +610,7 @@ 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 a2c091389b18..22500a526520 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -284,16 +284,29 @@ 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_pin_opts {
+ size_t sz; /* size of this struct for forward/backward compatibility */
+
+ int path_fd;
+
+ size_t :0;
+};
+#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 file_flags
+#define bpf_obj_get_opts__last_field path_fd

-LIBBPF_API int bpf_obj_pin(int fd, const char *pathname);
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 a5aa3a383d69..7a4fe80da360 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -389,5 +389,6 @@ LIBBPF_1.2.0 {
bpf_link__update_map;
bpf_link_get_info_by_fd;
bpf_map_get_info_by_fd;
+ bpf_obj_pin_opts;
bpf_prog_get_info_by_fd;
} LIBBPF_1.1.0;
--
2.34.1