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From:   Akihiko Odaki <akihiko.odaki@daynix.com>
Cc:     Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <martin.lau@linux.dev>,
        Song Liu <song@kernel.org>,
        Yonghong Song <yonghong.song@linux.dev>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>,
        Stanislav Fomichev <sdf@google.com>,
        Hao Luo <haoluo@google.com>, Jiri Olsa <jolsa@kernel.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
        Jason Wang <jasowang@redhat.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        Xuan Zhuo <xuanzhuo@linux.alibaba.com>,
        Mykola Lysenko <mykolal@fb.com>, Shuah Khan <shuah@kernel.org>,
        bpf@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        kvm@vger.kernel.org, virtualization@lists.linux-foundation.org,
        linux-kselftest@vger.kernel.org,
        Yuri Benditovich <yuri.benditovich@daynix.com>,
        Andrew Melnychenko <andrew@daynix.com>,
        Akihiko Odaki <akihiko.odaki@daynix.com>
Subject: [RFC PATCH v2 2/7] bpf: Add vnet_hash members to __sk_buff
Date:   Sun, 15 Oct 2023 23:16:30 +0900
Message-ID: <20231015141644.260646-3-akihiko.odaki@daynix.com>
In-Reply-To: <20231015141644.260646-1-akihiko.odaki@daynix.com>
References: <20231015141644.260646-1-akihiko.odaki@daynix.com>
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They will be used only by BPF_PROG_TYPE_VNET_HASH to tell the queues to
deliver packets and the hash values and types reported with virtio-net
headers.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
---
 include/linux/filter.h         |  7 ++++
 net/core/filter.c              | 77 +++++++++++++++++++++++++++++++++-
 tools/include/uapi/linux/bpf.h |  4 ++
 3 files changed, 86 insertions(+), 2 deletions(-)

diff --git a/include/linux/filter.h b/include/linux/filter.h
index bf7ad887943c..d10afe92ee45 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -643,6 +643,13 @@ struct bpf_skb_data_end {
 	void *data_end;
 };
 
+struct bpf_skb_vnet_hash_end {
+	struct qdisc_skb_cb qdisc_cb;
+	u32 hash_value;
+	u16 hash_report;
+	u16 rss_queue;
+};
+
 struct bpf_nh_params {
 	u32 nh_family;
 	union {
diff --git a/net/core/filter.c b/net/core/filter.c
index 867edbc628de..35bc60b71722 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -8435,9 +8435,15 @@ static bool bpf_skb_is_valid_access(int off, int size, enum bpf_access_type type
 	case bpf_ctx_range(struct __sk_buff, data):
 	case bpf_ctx_range(struct __sk_buff, data_meta):
 	case bpf_ctx_range(struct __sk_buff, data_end):
+	case bpf_ctx_range(struct __sk_buff, vnet_hash_value):
 		if (size != size_default)
 			return false;
 		break;
+	case bpf_ctx_range(struct __sk_buff, vnet_hash_report):
+	case bpf_ctx_range(struct __sk_buff, vnet_rss_queue):
+		if (size != sizeof(__u16))
+			return false;
+		break;
 	case bpf_ctx_range_ptr(struct __sk_buff, flow_keys):
 		return false;
 	case bpf_ctx_range(struct __sk_buff, hwtstamp):
@@ -8473,7 +8479,7 @@ static bool bpf_skb_is_valid_access(int off, int size, enum bpf_access_type type
 	return true;
 }
 
-static bool sk_filter_is_valid_access(int off, int size,
+static bool vnet_hash_is_valid_access(int off, int size,
 				      enum bpf_access_type type,
 				      const struct bpf_prog *prog,
 				      struct bpf_insn_access_aux *info)
@@ -8493,6 +8499,9 @@ static bool sk_filter_is_valid_access(int off, int size,
 	if (type == BPF_WRITE) {
 		switch (off) {
 		case bpf_ctx_range_till(struct __sk_buff, cb[0], cb[4]):
+		case bpf_ctx_range(struct __sk_buff, vnet_hash_value):
+		case bpf_ctx_range(struct __sk_buff, vnet_hash_report):
+		case bpf_ctx_range(struct __sk_buff, vnet_rss_queue):
 			break;
 		default:
 			return false;
@@ -8502,6 +8511,21 @@ static bool sk_filter_is_valid_access(int off, int size,
 	return bpf_skb_is_valid_access(off, size, type, prog, info);
 }
 
+static bool sk_filter_is_valid_access(int off, int size,
+				      enum bpf_access_type type,
+				      const struct bpf_prog *prog,
+				      struct bpf_insn_access_aux *info)
+{
+	switch (off) {
+	case bpf_ctx_range(struct __sk_buff, vnet_hash_value):
+	case bpf_ctx_range(struct __sk_buff, vnet_hash_report):
+	case bpf_ctx_range(struct __sk_buff, vnet_rss_queue):
+		return false;
+	}
+
+	return vnet_hash_is_valid_access(off, size, type, prog, info);
+}
+
 static bool cg_skb_is_valid_access(int off, int size,
 				   enum bpf_access_type type,
 				   const struct bpf_prog *prog,
@@ -8511,6 +8535,9 @@ static bool cg_skb_is_valid_access(int off, int size,
 	case bpf_ctx_range(struct __sk_buff, tc_classid):
 	case bpf_ctx_range(struct __sk_buff, data_meta):
 	case bpf_ctx_range(struct __sk_buff, wire_len):
+	case bpf_ctx_range(struct __sk_buff, vnet_hash_value):
+	case bpf_ctx_range(struct __sk_buff, vnet_hash_report):
+	case bpf_ctx_range(struct __sk_buff, vnet_rss_queue):
 		return false;
 	case bpf_ctx_range(struct __sk_buff, data):
 	case bpf_ctx_range(struct __sk_buff, data_end):
@@ -8558,6 +8585,9 @@ static bool lwt_is_valid_access(int off, int size,
 	case bpf_ctx_range(struct __sk_buff, tstamp):
 	case bpf_ctx_range(struct __sk_buff, wire_len):
 	case bpf_ctx_range(struct __sk_buff, hwtstamp):
+	case bpf_ctx_range(struct __sk_buff, vnet_hash_value):
+	case bpf_ctx_range(struct __sk_buff, vnet_hash_report):
+	case bpf_ctx_range(struct __sk_buff, vnet_rss_queue):
 		return false;
 	}
 
@@ -8799,6 +8829,10 @@ static bool tc_cls_act_is_valid_access(int off, int size,
 	}
 
 	switch (off) {
+	case bpf_ctx_range(struct __sk_buff, vnet_hash_value):
+	case bpf_ctx_range(struct __sk_buff, vnet_hash_report):
+	case bpf_ctx_range(struct __sk_buff, vnet_rss_queue):
+		return false;
 	case bpf_ctx_range(struct __sk_buff, data):
 		info->reg_type = PTR_TO_PACKET;
 		break;
@@ -9117,6 +9151,9 @@ static bool sk_skb_is_valid_access(int off, int size,
 	case bpf_ctx_range(struct __sk_buff, tstamp):
 	case bpf_ctx_range(struct __sk_buff, wire_len):
 	case bpf_ctx_range(struct __sk_buff, hwtstamp):
+	case bpf_ctx_range(struct __sk_buff, vnet_hash_value):
+	case bpf_ctx_range(struct __sk_buff, vnet_hash_report):
+	case bpf_ctx_range(struct __sk_buff, vnet_rss_queue):
 		return false;
 	}
 
@@ -9727,6 +9764,42 @@ static u32 bpf_convert_ctx_access(enum bpf_access_type type,
 						     hwtstamps, 8,
 						     target_size));
 		break;
+
+	case offsetof(struct __sk_buff, vnet_hash_value):
+		BUILD_BUG_ON(sizeof_field(struct bpf_skb_vnet_hash_end, hash_value) != 4);
+
+		off = offsetof(struct sk_buff, cb) +
+		      offsetof(struct bpf_skb_vnet_hash_end, hash_value);
+
+		if (type == BPF_WRITE)
+			*insn++ = BPF_EMIT_STORE(BPF_W, si, off);
+		else
+			*insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->src_reg, off);
+		break;
+
+	case offsetof(struct __sk_buff, vnet_hash_report):
+		BUILD_BUG_ON(sizeof_field(struct bpf_skb_vnet_hash_end, hash_report) != 2);
+
+		off = offsetof(struct sk_buff, cb) +
+		      offsetof(struct bpf_skb_vnet_hash_end, hash_report);
+
+		if (type == BPF_WRITE)
+			*insn++ = BPF_EMIT_STORE(BPF_H, si, off);
+		else
+			*insn++ = BPF_LDX_MEM(BPF_H, si->dst_reg, si->src_reg, off);
+		break;
+
+	case offsetof(struct __sk_buff, vnet_rss_queue):
+		BUILD_BUG_ON(sizeof_field(struct bpf_skb_vnet_hash_end, rss_queue) != 2);
+
+		off = offsetof(struct sk_buff, cb) +
+		      offsetof(struct bpf_skb_vnet_hash_end, rss_queue);
+
+		if (type == BPF_WRITE)
+			*insn++ = BPF_EMIT_STORE(BPF_H, si, off);
+		else
+			*insn++ = BPF_LDX_MEM(BPF_H, si->dst_reg, si->src_reg, off);
+		break;
 	}
 
 	return insn - insn_buf;
@@ -10969,7 +11042,7 @@ const struct bpf_prog_ops flow_dissector_prog_ops = {
 
 const struct bpf_verifier_ops vnet_hash_verifier_ops = {
 	.get_func_proto		= sk_filter_func_proto,
-	.is_valid_access	= sk_filter_is_valid_access,
+	.is_valid_access	= vnet_hash_is_valid_access,
 	.convert_ctx_access	= bpf_convert_ctx_access,
 	.gen_ld_abs		= bpf_gen_ld_abs,
 };
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 60976fe86247..298634556fab 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -6112,6 +6112,10 @@ struct __sk_buff {
 	__u8  tstamp_type;
 	__u32 :24;		/* Padding, future use. */
 	__u64 hwtstamp;
+
+	__u32 vnet_hash_value;
+	__u16 vnet_hash_report;
+	__u16 vnet_rss_queue;
 };
 
 struct bpf_tunnel_key {
-- 
2.42.0