Having a base CRC in module BTF allows us to reject base BTF
that does not match that CRC; this allows us to recognize
incompatible BTF up-front, not having to rely on invalidation
due to internal mismatches in module/kernel BTF ids.
Signed-off-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
---
kernel/bpf/btf.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 4eb13634580b..65a85bad13f7 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -5372,6 +5372,24 @@ static int btf_parse_hdr(struct btf_verifier_env *env)
return -EINVAL;
}
}
+ if (hdr->flags & BTF_FLAG_BASE_CRC_SET) {
+ struct btf_header *base_hdr = &btf->base_btf->hdr;
+
+ if (!btf->base_btf) {
+ btf_verifier_log(env, "Specified base BTF CRC but no base BTF");
+ return -EINVAL;
+ }
+
+ if (!(base_hdr->flags & BTF_FLAG_CRC_SET)) {
+ btf_verifier_log(env, "Specified base BTF CRC but base BTF has no CRC");
+ return -EINVAL;
+ }
+ if (hdr->base_crc != base_hdr->crc) {
+ btf_verifier_log(env, "Specified base CRC 0x%x; differs from actual base CRC 0x%x\n",
+ hdr->base_crc, base_hdr->crc);
+ return -EINVAL;
+ }
+ }
if (!btf->base_btf && btf_data_size == hdr->hdr_len) {
btf_verifier_log(env, "No data");
return -EINVAL;
--
2.31.1
