[PATCH bpf-next 14/29] libbpf: add BPF token support to bpf_btf_load() API

Andrii Nakryiko
2024-01-03T22:23:54Z

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.

Wire through new btf_flags as well, so that user can provide
BPF_F_TOKEN_FD flag, if necessary.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
tools/lib/bpf/bpf.c | 6 +++++-
tools/lib/bpf/bpf.h | 5 ++++-
2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 1653b64b7015..cf250cb1d5ef 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -1184,7 +1184,7 @@ 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;
@@ -1209,6 +1209,10 @@ 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_flags = OPTS_GET(opts, btf_flags, 0);
+ 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 ae2136f596b4..fde54ea08e6f 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -133,9 +133,12 @@ struct bpf_btf_load_opts {
* If kernel doesn't support this feature, log_size is left unchanged.
*/
__u32 log_true_size;
+
+ __u32 btf_flags;
+ __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