Introduce a libbpf API so that users can read data from a given BPF
stream for a BPF prog fd. For now, only the low-level syscall wrapper
is provided, we can add a bpf_program__* accessor as a follow up if
needed.
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Acked-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx>
---
tools/lib/bpf/bpf.c | 20 ++++++++++++++++++++
tools/lib/bpf/bpf.h | 21 +++++++++++++++++++++
tools/lib/bpf/libbpf.map | 1 +
3 files changed, 42 insertions(+)
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 6eb421ccf91b..ab40dbf9f020 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -1375,3 +1375,23 @@ int bpf_token_create(int bpffs_fd, struct bpf_token_create_opts *opts)
fd = sys_bpf_fd(BPF_TOKEN_CREATE, &attr, attr_sz);
return libbpf_err_errno(fd);
}
+
+int bpf_prog_stream_read(int prog_fd, __u32 stream_id, void *buf, __u32 buf_len,
+ struct bpf_prog_stream_read_opts *opts)
+{
+ const size_t attr_sz = offsetofend(union bpf_attr, prog_stream_read);
+ union bpf_attr attr;
+ int err;
+
+ if (!OPTS_VALID(opts, bpf_prog_stream_read_opts))
+ return libbpf_err(-EINVAL);
+
+ memset(&attr, 0, attr_sz);
+ attr.prog_stream_read.stream_buf = ptr_to_u64(buf);
+ attr.prog_stream_read.stream_buf_len = buf_len;
+ attr.prog_stream_read.stream_id = stream_id;
+ attr.prog_stream_read.prog_fd = prog_fd;
+
+ err = sys_bpf(BPF_PROG_STREAM_READ_BY_FD, &attr, attr_sz);
+ return libbpf_err_errno(err);
+}
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 1342564214c8..7252150e7ad3 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -709,6 +709,27 @@ struct bpf_token_create_opts {
LIBBPF_API int bpf_token_create(int bpffs_fd,
struct bpf_token_create_opts *opts);
+struct bpf_prog_stream_read_opts {
+ size_t sz;
+ size_t :0;
+};
+#define bpf_prog_stream_read_opts__last_field sz
+/**
+ * @brief **bpf_prog_stream_read** reads data from the BPF stream of a given BPF
+ * program.
+ *
+ * @param prog_fd FD for the BPF program whose BPF stream is to be read.
+ * @param stream_id ID of the BPF stream to be read.
+ * @param buf Buffer to read data into from the BPF stream.
+ * @param buf_len Maximum number of bytes to read from the BPF stream.
+ * @param opts optional options, can be NULL
+ *
+ * @return The number of bytes read, on success; negative error code, otherwise
+ * (errno is also set to the error code)
+ */
+LIBBPF_API int bpf_prog_stream_read(int prog_fd, __u32 stream_id, void *buf, __u32 buf_len,
+ struct bpf_prog_stream_read_opts *opts);
+
#ifdef __cplusplus
} /* extern "C" */
#endif
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index c7fc0bde5648..1bbf77326420 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -437,6 +437,7 @@ LIBBPF_1.6.0 {
bpf_linker__add_fd;
bpf_linker__new_fd;
bpf_object__prepare;
+ bpf_prog_stream_read;
bpf_program__attach_cgroup_opts;
bpf_program__func_info;
bpf_program__func_info_cnt;
--
2.47.1
