[PATCH 5.15 017/177] bpf, selftests: Add test case trying to taint map value pointer

Greg Kroah-Hartman
2021-12-20T15:04:15Z

From: Daniel Borkmann <daniel@iogearbox.net>

commit b1a7288dedc6caf9023f2676b4f5ed34cf0d4029 upstream.

Add a test case which tries to taint map value pointer arithmetic into a
unknown scalar with subsequent export through the map.

Before fix:

# ./test_verifier 1186
#1186/u map access: trying to leak tained dst reg FAIL
Unexpected success to load!
verification time 24 usec
stack depth 8
processed 15 insns (limit 1000000) max_states_per_insn 0 total_states 1 peak_states 1 mark_read 1
#1186/p map access: trying to leak tained dst reg FAIL
Unexpected success to load!
verification time 8 usec
stack depth 8
processed 15 insns (limit 1000000) max_states_per_insn 0 total_states 1 peak_states 1 mark_read 1
Summary: 0 PASSED, 0 SKIPPED, 2 FAILED

After fix:

# ./test_verifier 1186
#1186/u map access: trying to leak tained dst reg OK
#1186/p map access: trying to leak tained dst reg OK
Summary: 2 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
tools/testing/selftests/bpf/verifier/value_ptr_arith.c | 23 +++++++++++++++++
1 file changed, 23 insertions(+)

--- a/tools/testing/selftests/bpf/verifier/value_ptr_arith.c
+++ b/tools/testing/selftests/bpf/verifier/value_ptr_arith.c
@@ -1078,6 +1078,29 @@
.errstr_unpriv = "R0 pointer -= pointer prohibited",
},
{
+ "map access: trying to leak tained dst reg",
+ .insns = {
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ 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_JNE, BPF_REG_0, 0, 1),
+ BPF_EXIT_INSN(),
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_0),
+ BPF_MOV32_IMM(BPF_REG_1, 0xFFFFFFFF),
+ BPF_MOV32_REG(BPF_REG_1, BPF_REG_1),
+ BPF_ALU64_REG(BPF_SUB, BPF_REG_2, BPF_REG_1),
+ BPF_STX_MEM(BPF_DW, BPF_REG_0, BPF_REG_2, 0),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map_array_48b = { 4 },
+ .result = REJECT,
+ .errstr = "math between map_value pointer and 4294967295 is not allowed",
+},
+{
"32bit pkt_ptr -= scalar",
.insns = {
BPF_LDX_MEM(BPF_W, BPF_REG_8, BPF_REG_1,