Re: [PATCH bpf-next 1/2] bpf: add hardware timestamp field to __sk_buff
From: Daniel Borkmann <daniel@iogearbox.net>
Date: 2021-09-03 08:23:10
Also in:
bpf
On 9/3/21 12:15 AM, Vadim Fedorenko wrote:
quoted hunk ↗ jump to hunk
BPF programs may want to know hardware timestamps if NIC supports such timestamping. Expose this data as hwtstamp field of __sk_buff the same way as gso_segs/gso_size. Also update BPF_PROG_TEST_RUN tests of the feature. Signed-off-by: Vadim Fedorenko <redacted> --- include/uapi/linux/bpf.h | 2 ++ net/core/filter.c | 11 +++++++++++ tools/include/uapi/linux/bpf.h | 2 ++ 3 files changed, 15 insertions(+)diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 791f31dd0abe..c7d05b49f557 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h@@ -5284,6 +5284,8 @@ struct __sk_buff { __u32 gso_segs; __bpf_md_ptr(struct bpf_sock *, sk); __u32 gso_size; + __u32 padding; /* Padding, future use. */
nit, instead of explicit padding field, just use: __u32 :32; Also please add test_verifier coverage for this in BPF selftests, meaning, the expectation would be in case someone tries to access the padding field with this patch that we get a 'bpf verifier is misconfigured' error given it would have no bpf_convert_ctx_access() translation. But it would be overall better to add this to bpf_skb_is_valid_access(), so we can reject access to the padding area right there instead.
quoted hunk ↗ jump to hunk
+ __u64 hwtstamp; }; struct bpf_tunnel_key {diff --git a/net/core/filter.c b/net/core/filter.c index 2e32cee2c469..1d8f8494d325 100644 --- a/net/core/filter.c +++ b/net/core/filter.c@@ -8884,6 +8884,17 @@ static u32 bpf_convert_ctx_access(enum bpf_access_type type, si->dst_reg, si->src_reg, offsetof(struct sk_buff, sk)); 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, + target_size)); + break; } return insn - insn_buf;diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 791f31dd0abe..c7d05b49f557 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h@@ -5284,6 +5284,8 @@ struct __sk_buff { __u32 gso_segs; __bpf_md_ptr(struct bpf_sock *, sk); __u32 gso_size; + __u32 padding; /* Padding, future use. */ + __u64 hwtstamp; }; struct bpf_tunnel_key {