[RFC PATCH net-next 1/6] bpf: Access hwtstamp field of hwtstamps directly
From: Gerhard Engleder <hidden>
Date: 2022-03-06 08:57:46
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [networking] (tcx & tc bpf, sock_addr), networking [general], the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
skb_shared_hwtstamps contains only the field hwtstamp. That property is hard-coded and checked during build in BPF. bpf_target_off() gets the whole structure as argument (hwtstamps) instead of the actually accessed field hwtstamp. Access hwtstamp field directly and allow future extensions of skb_shared_hwtstamps. Signed-off-by: Gerhard Engleder <redacted> --- net/core/filter.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/net/core/filter.c b/net/core/filter.c
index 88767f7da150..09e202b60060 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c@@ -9364,13 +9364,12 @@ static u32 bpf_convert_ctx_access(enum bpf_access_type type, break; case offsetof(struct __sk_buff, hwtstamp): BUILD_BUG_ON(sizeof_field(struct skb_shared_hwtstamps, hwtstamp) != 8); - BUILD_BUG_ON(offsetof(struct skb_shared_hwtstamps, hwtstamp) != 0); insn = bpf_convert_shinfo_access(si, insn); *insn++ = BPF_LDX_MEM(BPF_DW, si->dst_reg, si->dst_reg, bpf_target_off(struct skb_shared_info, - hwtstamps, 8, + hwtstamps.hwtstamp, 8, target_size)); break; }
--
2.20.1