[PATCH bpf-next 2/2] testcases/bpf: add testcases for skb->csum to ctx_skb.c

[Menglong Dong <menglong8.dong@xxxxxxxxx>]

The testcases for read/write access of skb->csum is added to ctx_skb.c.
And the read access testing for skb->ip_summed is also added.

Signed-off-by: Menglong Dong <menglong8.dong@xxxxxxxxx>
---
 .../testing/selftests/bpf/verifier/ctx_skb.c  | 43 +++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/tools/testing/selftests/bpf/verifier/ctx_skb.c b/tools/testing/selftests/bpf/verifier/ctx_skb.c
index 0b394a7f7a2d..f15301686843 100644
--- a/tools/testing/selftests/bpf/verifier/ctx_skb.c
+++ b/tools/testing/selftests/bpf/verifier/ctx_skb.c
@@ -1193,3 +1193,46 @@
        .prog_type = BPF_PROG_TYPE_SK_SKB,
        .flags = F_NEEDS_EFFICIENT_UNALIGNED_ACCESS,
 },
+{
+	"valid access __sk_buff csum",
+	.insns = {
+	BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
+		    offsetof(struct __sk_buff, csum)),
+	BPF_EXIT_INSN(),
+	},
+	.result = ACCEPT,
+	.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+},
+{
+	"valid access __sk_buff ip_summed",
+	.insns = {
+	BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
+		    offsetof(struct __sk_buff, ip_summed)),
+	BPF_EXIT_INSN(),
+	},
+	.result = ACCEPT,
+	.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+},
+{
+	"check skb->csum is writeable by CLS/ACT",
+	.insns = {
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
+		    offsetof(struct __sk_buff, csum)),
+	BPF_EXIT_INSN(),
+	},
+	.result =  ACCEPT,
+	.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+	.errstr = "invalid bpf_context access",
+},
+{
+	"check skb->ip_summed is not writeable",
+	.insns = {
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0,
+		    offsetof(struct __sk_buff, csum)),
+	BPF_EXIT_INSN(),
+	},
+	.result =  REJECT,
+	.errstr = "invalid bpf_context access",
+},
-- 
2.39.2