From: Daniel Borkmann <daniel@iogearbox.net>
Date: Wed, 15 Dec 2021 23:48:54 +0000
Subject: bpf, selftests: Add test case trying to taint map value pointer
Git-commit: b1a7288dedc6caf9023f2676b4f5ed34cf0d4029
Patch-mainline: v5.16-rc6
References: bsc#1196130,CVE-2021-45402

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: Tony Jones <tonyj@suse.de>
---
 .../selftests/bpf/verifier/value_ptr_arith.c       | 23 ++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/tools/testing/selftests/bpf/verifier/value_ptr_arith.c b/tools/testing/selftests/bpf/verifier/value_ptr_arith.c
index 2debba4e8a3a..4d347bc53aa2 100644
--- a/tools/testing/selftests/bpf/verifier/value_ptr_arith.c
+++ b/tools/testing/selftests/bpf/verifier/value_ptr_arith.c
@@ -1077,6 +1077,29 @@
 	.errstr = "R0 invalid mem access 'inv'",
 	.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 = {