bpf: Add __bpf_dynptr_data* for in kernel use

Different types of bpf dynptr have different internal data storage.
Specifically, SKB and XDP type of dynptr may have non-continuous data.
Therefore, it is not always safe to directly access dynptr->data.

Add __bpf_dynptr_data and __bpf_dynptr_data_rw to replace direct access to
dynptr->data.

Update bpf_verify_pkcs7_signature to use __bpf_dynptr_data instead of
dynptr->data.

Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Link: https://lore.kernel.org/bpf/20231107045725.2278852-2-song@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index b4825d3cdb29..eb84caf133df 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1222,6 +1222,8 @@ enum bpf_dynptr_type {
 
 int bpf_dynptr_check_size(u32 size);
 u32 __bpf_dynptr_size(const struct bpf_dynptr_kern *ptr);
+const void *__bpf_dynptr_data(const struct bpf_dynptr_kern *ptr, u32 len);
+void *__bpf_dynptr_data_rw(const struct bpf_dynptr_kern *ptr, u32 len);
 
 #ifdef CONFIG_BPF_JIT
 int bpf_trampoline_link_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr);