[PATCH v2 bpf-next 11/18] libbpf: add BPF token support to bpf_btf_load() API

Andrii Nakryiko
2023-06-07T23:54:33Z

Allow user to specify token_fd for bpf_btf_load() API that wraps
kernel's BPF_BTF_LOAD command. This allows loading BTF from unprivileged
process as long as it has BPF token allowing BPF_BTF_LOAD command, which
can be created and delegated by privileged process.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
tools/lib/bpf/bpf.c | 4 +++-
tools/lib/bpf/bpf.h | 3 ++-
2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 0318538d43eb..193993dbbdc4 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -1098,7 +1098,7 @@ int bpf_raw_tracepoint_open(const char *name, int prog_fd)

int bpf_btf_load(const void *btf_data, size_t btf_size, struct bpf_btf_load_opts *opts)
{
- const size_t attr_sz = offsetofend(union bpf_attr, btf_log_true_size);
+ const size_t attr_sz = offsetofend(union bpf_attr, btf_token_fd);
union bpf_attr attr;
char *log_buf;
size_t log_size;
@@ -1123,6 +1123,8 @@ int bpf_btf_load(const void *btf_data, size_t btf_size, struct bpf_btf_load_opts

attr.btf = ptr_to_u64(btf_data);
attr.btf_size = btf_size;
+ attr.btf_token_fd = OPTS_GET(opts, token_fd, 0);
+
/* log_level == 0 and log_buf != NULL means "try loading without
* log_buf, but retry with log_buf and log_level=1 on error", which is
* consistent across low-level and high-level BTF and program loading
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 19a43201d1af..3153a9e697e2 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -132,9 +132,10 @@ struct bpf_btf_load_opts {
* If kernel doesn't support this feature, log_size is left unchanged.
*/
__u32 log_true_size;
+ __u32 token_fd;
size_t :0;
};
-#define bpf_btf_load_opts__last_field log_true_size
+#define bpf_btf_load_opts__last_field token_fd

LIBBPF_API int bpf_btf_load(const void *btf_data, size_t btf_size,
struct bpf_btf_load_opts *opts);
--
2.34.1