[v2,bpf-next,1/9] bpf: Expose bpf_dynptr_slice* kfuncs for in kernel use

Commit Message

Song Liu Oct. 23, 2023, 6:13 a.m. UTC

These kfuncs can be used to access the dynptr data. Expose them in bpf.h
and use bpf_dynptr_slice in bpf_verify_pkcs7_signature.

Signed-off-by: Song Liu <[e-mail]>
---
 include/linux/bpf.h      |  4 ++++
 kernel/trace/bpf_trace.c | 15 +++++++++++----
 2 files changed, 15 insertions(+), 4 deletions(-)

Patch

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index b4b40b45962b..0d4e795a8a73 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1222,6 +1222,10 @@  enum bpf_dynptr_type {
 
 int bpf_dynptr_check_size(u32 size);
 u32 __bpf_dynptr_size(const struct bpf_dynptr_kern *ptr);
+void *bpf_dynptr_slice(const struct bpf_dynptr_kern *ptr, u32 offset,
+		       void *buffer__opt, u32 buffer__szk);
+void *bpf_dynptr_slice_rdwr(const struct bpf_dynptr_kern *ptr, u32 offset,
+			    void *buffer__opt, u32 buffer__szk);
 
 #ifdef CONFIG_BPF_JIT
 int bpf_trampoline_link_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr);
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index df697c74d519..43ed45a83ee2 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1378,6 +1378,7 @@  __bpf_kfunc int bpf_verify_pkcs7_signature(struct bpf_dynptr_kern *data_ptr,
 			       struct bpf_dynptr_kern *sig_ptr,
 			       struct bpf_key *trusted_keyring)
 {
+	void *data, *sig;
 	int ret;
 
 	if (trusted_keyring->has_ref) {
@@ -1394,10 +1395,16 @@  __bpf_kfunc int bpf_verify_pkcs7_signature(struct bpf_dynptr_kern *data_ptr,
 			return ret;
 	}
 
-	return verify_pkcs7_signature(data_ptr->data,
-				      __bpf_dynptr_size(data_ptr),
-				      sig_ptr->data,
-				      __bpf_dynptr_size(sig_ptr),
+	data = bpf_dynptr_slice(data_ptr, 0, NULL, 0);
+	if (IS_ERR_OR_NULL(data))
+		return PTR_ERR(data);
+
+	sig = bpf_dynptr_slice(sig_ptr, 0, NULL, 0);
+	if (IS_ERR_OR_NULL(sig))
+		return PTR_ERR(sig);
+
+	return verify_pkcs7_signature(data, __bpf_dynptr_size(data_ptr),
+				      sig, __bpf_dynptr_size(sig_ptr),
 				      trusted_keyring->key,
 				      VERIFYING_UNSPECIFIED_SIGNATURE, NULL,
 				      NULL);