netdev - [PATCH bpf-next v3 1/2] bpf: add CHECKSUM

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Date: Mon, 27 May 2024 11:59:27 -0700
From: Vadim Fedorenko <vadfed@...a.com>
To: Vadim Fedorenko <vadim.fedorenko@...ux.dev>,
        Martin KaFai Lau
	<martin.lau@...ux.dev>,
        Andrii Nakryiko <andrii@...nel.org>,
        "Alexei
 Starovoitov" <ast@...nel.org>,
        Mykola Lysenko <mykolal@...com>, Jakub
 Kicinski <kuba@...nel.org>
CC: Vadim Fedorenko <vadfed@...a.com>, <bpf@...r.kernel.org>,
        <netdev@...r.kernel.org>
Subject: [PATCH bpf-next v3 1/2] bpf: add CHECKSUM_COMPLETE to bpf test progs

Add special flag to validate that TC BPF program properly updates
checksum information in skb.

Signed-off-by: Vadim Fedorenko <vadfed@...a.com>
---
 include/uapi/linux/bpf.h       |  2 ++
 net/bpf/test_run.c             | 18 +++++++++++++++++-
 tools/include/uapi/linux/bpf.h |  2 ++
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 90706a47f6ff..f7d458d88111 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1425,6 +1425,8 @@ enum {
 #define BPF_F_TEST_RUN_ON_CPU	(1U << 0)
 /* If set, XDP frames will be transmitted after processing */
 #define BPF_F_TEST_XDP_LIVE_FRAMES	(1U << 1)
+/* If set, apply CHECKSUM_COMPLETE to skb and validate the checksum */
+#define BPF_F_TEST_SKB_CHECKSUM_COMPLETE	(1U << 2)
 
 /* type for BPF_ENABLE_STATS */
 enum bpf_stats_type {
diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index f6aad4ed2ab2..4c21562ad526 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -977,7 +977,8 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
 	void *data;
 	int ret;
 
-	if (kattr->test.flags || kattr->test.cpu || kattr->test.batch_size)
+	if ((kattr->test.flags & ~BPF_F_TEST_SKB_CHECKSUM_COMPLETE) ||
+	    kattr->test.cpu || kattr->test.batch_size)
 		return -EINVAL;
 
 	data = bpf_test_init(kattr, kattr->test.data_size_in,
@@ -1025,6 +1026,12 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
 
 	skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
 	__skb_put(skb, size);
+
+	if (kattr->test.flags & BPF_F_TEST_SKB_CHECKSUM_COMPLETE) {
+		skb->csum = skb_checksum(skb, 0, skb->len, 0);
+		skb->ip_summed = CHECKSUM_COMPLETE;
+	}
+
 	if (ctx && ctx->ifindex > 1) {
 		dev = dev_get_by_index(net, ctx->ifindex);
 		if (!dev) {
@@ -1079,6 +1086,15 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
 	}
 	convert_skb_to___skb(skb, ctx);
 
+	if (kattr->test.flags & BPF_F_TEST_SKB_CHECKSUM_COMPLETE) {
+		__wsum csum = skb_checksum(skb, 0, skb->len, 0);
+
+		if (skb->csum != csum) {
+			ret = -EBADMSG;
+			goto out;
+		}
+	}
+
 	size = skb->len;
 	/* bpf program can never convert linear skb to non-linear */
 	if (WARN_ON_ONCE(skb_is_nonlinear(skb)))
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 90706a47f6ff..f7d458d88111 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1425,6 +1425,8 @@ enum {
 #define BPF_F_TEST_RUN_ON_CPU	(1U << 0)
 /* If set, XDP frames will be transmitted after processing */
 #define BPF_F_TEST_XDP_LIVE_FRAMES	(1U << 1)
+/* If set, apply CHECKSUM_COMPLETE to skb and validate the checksum */
+#define BPF_F_TEST_SKB_CHECKSUM_COMPLETE	(1U << 2)
 
 /* type for BPF_ENABLE_STATS */
 enum bpf_stats_type {
-- 
2.43.0