[PATCH disco 1/3] selftests/bpf: Test narrow loads with off > 0 in test_verifier

[Thadeu Lima de Souza Cascardo]

From: Andrey Ignatov <rdna at fb.com>

Test the following narrow loads in test_verifier for context __sk_buff:
* off=1, size=1 - ok;
* off=2, size=1 - ok;
* off=3, size=1 - ok;
* off=0, size=2 - ok;
* off=1, size=2 - fail;
* off=0, size=2 - ok;
* off=3, size=2 - fail.

Signed-off-by: Andrey Ignatov <rdna at fb.com>
Signed-off-by: Alexei Starovoitov <ast at kernel.org>
(cherry picked from commit 6c2afb674dbda9b736b8f09c976516e1e788860a)
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo at canonical.com>
---
 tools/testing/selftests/bpf/test_verifier.c | 48 ++++++++++++++++-----
 1 file changed, 38 insertions(+), 10 deletions(-)

diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index 9db5a7378f40..d9adb492c2c8 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -2002,29 +2002,27 @@ static struct bpf_test tests[] = {
 		.result = ACCEPT,
 	},
 	{
-		"check skb->hash byte load not permitted 1",
+		"check skb->hash byte load permitted 1",
 		.insns = {
 			BPF_MOV64_IMM(BPF_REG_0, 0),
 			BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_1,
 				    offsetof(struct __sk_buff, hash) + 1),
 			BPF_EXIT_INSN(),
 		},
-		.errstr = "invalid bpf_context access",
-		.result = REJECT,
+		.result = ACCEPT,
 	},
 	{
-		"check skb->hash byte load not permitted 2",
+		"check skb->hash byte load permitted 2",
 		.insns = {
 			BPF_MOV64_IMM(BPF_REG_0, 0),
 			BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_1,
 				    offsetof(struct __sk_buff, hash) + 2),
 			BPF_EXIT_INSN(),
 		},
-		.errstr = "invalid bpf_context access",
-		.result = REJECT,
+		.result = ACCEPT,
 	},
 	{
-		"check skb->hash byte load not permitted 3",
+		"check skb->hash byte load permitted 3",
 		.insns = {
 			BPF_MOV64_IMM(BPF_REG_0, 0),
 #if __BYTE_ORDER == __LITTLE_ENDIAN
@@ -2036,8 +2034,7 @@ static struct bpf_test tests[] = {
 #endif
 			BPF_EXIT_INSN(),
 		},
-		.errstr = "invalid bpf_context access",
-		.result = REJECT,
+		.result = ACCEPT,
 	},
 	{
 		"check cb access: byte, wrong type",
@@ -2149,7 +2146,7 @@ static struct bpf_test tests[] = {
 		.result = ACCEPT,
 	},
 	{
-		"check skb->hash half load not permitted",
+		"check skb->hash half load permitted 2",
 		.insns = {
 			BPF_MOV64_IMM(BPF_REG_0, 0),
 #if __BYTE_ORDER == __LITTLE_ENDIAN
@@ -2158,6 +2155,37 @@ static struct bpf_test tests[] = {
 #else
 			BPF_LDX_MEM(BPF_H, BPF_REG_0, BPF_REG_1,
 				    offsetof(struct __sk_buff, hash)),
+#endif
+			BPF_EXIT_INSN(),
+		},
+		.result = ACCEPT,
+	},
+	{
+		"check skb->hash half load not permitted, unaligned 1",
+		.insns = {
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+			BPF_LDX_MEM(BPF_H, BPF_REG_0, BPF_REG_1,
+				    offsetof(struct __sk_buff, hash) + 1),
+#else
+			BPF_LDX_MEM(BPF_H, BPF_REG_0, BPF_REG_1,
+				    offsetof(struct __sk_buff, hash) + 3),
+#endif
+			BPF_EXIT_INSN(),
+		},
+		.errstr = "invalid bpf_context access",
+		.result = REJECT,
+	},
+	{
+		"check skb->hash half load not permitted, unaligned 3",
+		.insns = {
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+			BPF_LDX_MEM(BPF_H, BPF_REG_0, BPF_REG_1,
+				    offsetof(struct __sk_buff, hash) + 3),
+#else
+			BPF_LDX_MEM(BPF_H, BPF_REG_0, BPF_REG_1,
+				    offsetof(struct __sk_buff, hash) + 1),
 #endif
 			BPF_EXIT_INSN(),
 		},
-- 
2.20.1