netdev - [PATCH net-next][v2] bpf: test for AND edge cases

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Date:   Fri, 3 Feb 2017 16:25:23 -0500
From:   Josef Bacik <jbacik@...com>
To:     <kernel-team@...com>, <netdev@...r.kernel.org>,
        <davem@...emloft.net>
Subject: [PATCH net-next][v2] bpf: test for AND edge cases

These two tests are based on the work done for f23cc643f9ba.  The first test is
just a basic one to make sure we don't allow AND'ing negative values, even if it
would result in a valid index for the array.  The second is a cleaned up version
of the original testcase provided by Jann Horn that resulted in the commit.

Acked-by: Alexei Starovoitov <ast@...nel.org>
Acked-by: Daniel Borkmann <daniel@...earbox.net>
Signed-off-by: Josef Bacik <jbacik@...com>
---
v1->v2:
-rebased onto net-next

 tools/testing/selftests/bpf/test_verifier.c | 55 +++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index 0d0912c..df194e1 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -4370,6 +4370,61 @@ static struct bpf_test tests[] = {
 		.result = ACCEPT,
 		.prog_type = BPF_PROG_TYPE_TRACEPOINT,
 	},
+	{
+		"invalid and of negative number",
+		.insns = {
+			BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
+			BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+			BPF_LD_MAP_FD(BPF_REG_1, 0),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
+				     BPF_FUNC_map_lookup_elem),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 4),
+			BPF_MOV64_IMM(BPF_REG_1, 6),
+			BPF_ALU64_IMM(BPF_AND, BPF_REG_1, -4),
+			BPF_ALU64_IMM(BPF_LSH, BPF_REG_1, 2),
+			BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_1),
+			BPF_ST_MEM(BPF_DW, BPF_REG_0, 0,
+				   offsetof(struct test_val, foo)),
+			BPF_EXIT_INSN(),
+		},
+		.fixup_map2 = { 3 },
+		.errstr_unpriv = "R0 pointer arithmetic prohibited",
+		.errstr = "R0 min value is negative, either use unsigned index or do a if (index >=0) check.",
+		.result = REJECT,
+		.result_unpriv = REJECT,
+	},
+	{
+		"invalid range check",
+		.insns = {
+			BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
+			BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+			BPF_LD_MAP_FD(BPF_REG_1, 0),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
+				     BPF_FUNC_map_lookup_elem),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 12),
+			BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_0, 0),
+			BPF_MOV64_IMM(BPF_REG_9, 1),
+			BPF_ALU32_IMM(BPF_MOD, BPF_REG_1, 2),
+			BPF_ALU32_IMM(BPF_ADD, BPF_REG_1, 1),
+			BPF_ALU32_REG(BPF_AND, BPF_REG_9, BPF_REG_1),
+			BPF_ALU32_IMM(BPF_ADD, BPF_REG_9, 1),
+			BPF_ALU32_IMM(BPF_RSH, BPF_REG_9, 1),
+			BPF_MOV32_IMM(BPF_REG_3, 1),
+			BPF_ALU32_REG(BPF_SUB, BPF_REG_3, BPF_REG_9),
+			BPF_ALU32_IMM(BPF_MUL, BPF_REG_3, 0x10000000),
+			BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_3),
+			BPF_STX_MEM(BPF_W, BPF_REG_0, BPF_REG_3, 0),
+			BPF_MOV64_REG(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+		},
+		.fixup_map2 = { 3 },
+		.errstr_unpriv = "R0 pointer arithmetic prohibited",
+		.errstr = "R0 min value is negative, either use unsigned index or do a if (index >=0) check.",
+		.result = REJECT,
+		.result_unpriv = REJECT,
+	}
 };
 
 static int probe_filter_length(const struct bpf_insn *fp)
-- 
2.7.4