[PATCHv13 bpf-next 5/6] selftests/bpf: Add verifier tests for bpf arg ARG_CONST_MAP_PTR_OR_NULL

Hangbin Liu
2020-12-21T12:36:46Z

Use helper bpf_redirect_map() and bpf_redirect_map_multi() to test bpf
arg ARG_CONST_MAP_PTR and ARG_CONST_MAP_PTR_OR_NULL. Make sure the
map arg could be verified correctly when it is NULL or valid map
pointer.

Add devmap and devmap_hash in struct bpf_test due to bpf_redirect_{map,
map_multi} limit.

Test result:
]# ./test_verifier 713 716
#713/p ARG_CONST_MAP_PTR: null pointer OK
#714/p ARG_CONST_MAP_PTR: valid map pointer OK
#715/p ARG_CONST_MAP_PTR_OR_NULL: null pointer for ex_map OK
#716/p ARG_CONST_MAP_PTR_OR_NULL: valid map pointer for ex_map OK
Summary: 4 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
---
tools/testing/selftests/bpf/test_verifier.c | 22 +++++-
.../testing/selftests/bpf/verifier/map_ptr.c | 70 +++++++++++++++++++
2 files changed, 91 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index 777a81404fdb..17eb3958ce6d 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -50,7 +50,7 @@
#define MAX_INSNS BPF_MAXINSNS
#define MAX_TEST_INSNS 1000000
#define MAX_FIXUPS 8
-#define MAX_NR_MAPS 20
+#define MAX_NR_MAPS 22
#define MAX_TEST_RUNS 8
#define POINTER_VALUE 0xcafe4all
#define TEST_DATA_LEN 64
@@ -87,6 +87,8 @@ struct bpf_test {
int fixup_sk_storage_map[MAX_FIXUPS];
int fixup_map_event_output[MAX_FIXUPS];
int fixup_map_reuseport_array[MAX_FIXUPS];
+ int fixup_map_devmap[MAX_FIXUPS];
+ int fixup_map_devmap_hash[MAX_FIXUPS];
const char *errstr;
const char *errstr_unpriv;
uint32_t insn_processed;
@@ -640,6 +642,8 @@ static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type,
int *fixup_sk_storage_map = test->fixup_sk_storage_map;
int *fixup_map_event_output = test->fixup_map_event_output;
int *fixup_map_reuseport_array = test->fixup_map_reuseport_array;
+ int *fixup_map_devmap = test->fixup_map_devmap;
+ int *fixup_map_devmap_hash = test->fixup_map_devmap_hash;

if (test->fill_helper) {
test->fill_insns = calloc(MAX_TEST_INSNS, sizeof(struct bpf_insn));
@@ -817,6 +821,22 @@ static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type,
fixup_map_reuseport_array++;
} while (*fixup_map_reuseport_array);
}
+ if (*fixup_map_devmap) {
+ map_fds[20] = __create_map(BPF_MAP_TYPE_DEVMAP,
+ sizeof(u32), sizeof(u32), 1, 0);
+ do {
+ prog[*fixup_map_devmap].imm = map_fds[20];
+ fixup_map_devmap++;
+ } while (*fixup_map_devmap);
+ }
+ if (*fixup_map_devmap_hash) {
+ map_fds[21] = __create_map(BPF_MAP_TYPE_DEVMAP_HASH,
+ sizeof(u32), sizeof(u32), 1, 0);
+ do {
+ prog[*fixup_map_devmap_hash].imm = map_fds[21];
+ fixup_map_devmap_hash++;
+ } while (*fixup_map_devmap_hash);
+ }
}

struct libcap {
diff --git a/tools/testing/selftests/bpf/verifier/map_ptr.c b/tools/testing/selftests/bpf/verifier/map_ptr.c
index b117bdd3806d..1a532198c9c1 100644
--- a/tools/testing/selftests/bpf/verifier/map_ptr.c
+++ b/tools/testing/selftests/bpf/verifier/map_ptr.c
@@ -93,3 +93,73 @@
.fixup_map_hash_16b = { 4 },
.result = ACCEPT,
},
+{
+ "ARG_CONST_MAP_PTR: null pointer",
+ .insns = {
+ /* bpf_redirect_map arg1 (map) */
+ BPF_MOV64_IMM(BPF_REG_1, 0),
+ /* bpf_redirect_map arg2 (ifindex) */
+ BPF_MOV64_IMM(BPF_REG_2, 0),
+ /* bpf_redirect_map arg3 (flags) */
+ BPF_MOV64_IMM(BPF_REG_3, 0),
+ BPF_EMIT_CALL(BPF_FUNC_redirect_map),
+ BPF_EXIT_INSN(),
+ },
+ .result = REJECT,
+ .prog_type = BPF_PROG_TYPE_XDP,
+ .errstr = "R1 type=inv expected=map_ptr",
+},
+{
+ "ARG_CONST_MAP_PTR: valid map pointer",
+ .insns = {
+ BPF_MOV64_IMM(BPF_REG_1, 0),
+ /* bpf_redirect_map arg1 (map) */
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ /* bpf_redirect_map arg2 (ifindex) */
+ BPF_MOV64_IMM(BPF_REG_2, 0),
+ /* bpf_redirect_map arg3 (flags) */
+ BPF_MOV64_IMM(BPF_REG_3, 0),
+ BPF_EMIT_CALL(BPF_FUNC_redirect_map),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map_devmap = { 1 },
+ .result = ACCEPT,
+ .prog_type = BPF_PROG_TYPE_XDP,
+},
+{
+ "ARG_CONST_MAP_PTR_OR_NULL: null pointer for ex_map",
+ .insns = {
+ BPF_MOV64_IMM(BPF_REG_1, 0),
+ /* bpf_redirect_map_multi arg1 (in_map) */
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ /* bpf_redirect_map_multi arg2 (ex_map) */
+ BPF_MOV64_IMM(BPF_REG_2, 0),
+ /* bpf_redirect_map_multi arg3 (flags) */
+ BPF_MOV64_IMM(BPF_REG_3, 0),
+ BPF_EMIT_CALL(BPF_FUNC_redirect_map_multi),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map_devmap = { 1 },
+ .result = ACCEPT,
+ .prog_type = BPF_PROG_TYPE_XDP,
+ .retval = 4,
+},
+{
+ "ARG_CONST_MAP_PTR_OR_NULL: valid map pointer for ex_map",
+ .insns = {
+ BPF_MOV64_IMM(BPF_REG_1, 0),
+ /* bpf_redirect_map_multi arg1 (in_map) */
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ /* bpf_redirect_map_multi arg2 (ex_map) */
+ BPF_LD_MAP_FD(BPF_REG_2, 1),
+ /* bpf_redirect_map_multi arg3 (flags) */
+ BPF_MOV64_IMM(BPF_REG_3, 0),
+ BPF_EMIT_CALL(BPF_FUNC_redirect_map_multi),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map_devmap = { 1 },
+ .fixup_map_devmap_hash = { 3 },
+ .result = ACCEPT,
+ .prog_type = BPF_PROG_TYPE_XDP,
+ .retval = 4,
+},
--
2.26.2