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@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index 0d0912c..df194e1 100644 (file)
--- 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)