Re: [PATCH v16 09/12] selftests/bpf: Add verifier tests for bpf_lookup_*_key() and bpf_key_put()

[Kumar Kartikeya Dwivedi]

On Mon, 5 Sept 2022 at 16:36, Roberto Sassu
<roberto.sassu@xxxxxxxxxxxxxxx> wrote:
>
> From: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
>
> Add verifier tests for bpf_lookup_*_key() and bpf_key_put(), to ensure that
> acquired key references stored in the bpf_key structure are released, that
> a non-NULL bpf_key pointer is passed to bpf_key_put(), and that key
> references are not leaked.
>
> Also, slightly modify test_verifier.c, to find the BTF ID of the attach
> point for the LSM program type (currently, it is done only for TRACING).
>
> Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
> ---

Acked-by: Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx>

>  tools/testing/selftests/bpf/config            |   1 +
>  tools/testing/selftests/bpf/test_verifier.c   |   3 +-
>  .../selftests/bpf/verifier/ref_tracking.c     | 139 ++++++++++++++++++
>  3 files changed, 142 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/bpf/config b/tools/testing/selftests/bpf/config
> index 0fdd11e6b742..add5a5a919b4 100644
> --- a/tools/testing/selftests/bpf/config
> +++ b/tools/testing/selftests/bpf/config
> @@ -30,6 +30,7 @@ CONFIG_IPV6_GRE=y
>  CONFIG_IPV6_SEG6_BPF=y
>  CONFIG_IPV6_SIT=y
>  CONFIG_IPV6_TUNNEL=y
> +CONFIG_KEYS=y
>  CONFIG_LIRC=y
>  CONFIG_LWTUNNEL=y
>  CONFIG_MPLS=y
> diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
> index f9d553fbf68a..2dbcbf363c18 100644
> --- a/tools/testing/selftests/bpf/test_verifier.c
> +++ b/tools/testing/selftests/bpf/test_verifier.c
> @@ -1498,7 +1498,8 @@ static void do_test_single(struct bpf_test *test, bool unpriv,
>                 opts.log_level = DEFAULT_LIBBPF_LOG_LEVEL;
>         opts.prog_flags = pflags;
>
> -       if (prog_type == BPF_PROG_TYPE_TRACING && test->kfunc) {
> +       if ((prog_type == BPF_PROG_TYPE_TRACING ||
> +            prog_type == BPF_PROG_TYPE_LSM) && test->kfunc) {
>                 int attach_btf_id;
>
>                 attach_btf_id = libbpf_find_vmlinux_btf_id(test->kfunc,
> diff --git a/tools/testing/selftests/bpf/verifier/ref_tracking.c b/tools/testing/selftests/bpf/verifier/ref_tracking.c
> index 57a83d763ec1..f18ce867271f 100644
> --- a/tools/testing/selftests/bpf/verifier/ref_tracking.c
> +++ b/tools/testing/selftests/bpf/verifier/ref_tracking.c
> @@ -84,6 +84,145 @@
>         .errstr = "Unreleased reference",
>         .result = REJECT,
>  },
> +{
> +       "reference tracking: acquire/release user key reference",
> +       .insns = {
> +       BPF_MOV64_IMM(BPF_REG_1, -3),
> +       BPF_MOV64_IMM(BPF_REG_2, 0),
> +       BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
> +       BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
> +       BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
> +       BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
> +       BPF_MOV64_IMM(BPF_REG_0, 0),
> +       BPF_EXIT_INSN(),
> +       },
> +       .prog_type = BPF_PROG_TYPE_LSM,
> +       .kfunc = "bpf",
> +       .expected_attach_type = BPF_LSM_MAC,
> +       .flags = BPF_F_SLEEPABLE,
> +       .fixup_kfunc_btf_id = {
> +               { "bpf_lookup_user_key", 2 },
> +               { "bpf_key_put", 5 },
> +       },
> +       .result = ACCEPT,
> +},
> +{
> +       "reference tracking: acquire/release system key reference",
> +       .insns = {
> +       BPF_MOV64_IMM(BPF_REG_1, 1),
> +       BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
> +       BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
> +       BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
> +       BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
> +       BPF_MOV64_IMM(BPF_REG_0, 0),
> +       BPF_EXIT_INSN(),
> +       },
> +       .prog_type = BPF_PROG_TYPE_LSM,
> +       .kfunc = "bpf",
> +       .expected_attach_type = BPF_LSM_MAC,
> +       .flags = BPF_F_SLEEPABLE,
> +       .fixup_kfunc_btf_id = {
> +               { "bpf_lookup_system_key", 1 },
> +               { "bpf_key_put", 4 },
> +       },
> +       .result = ACCEPT,
> +},
> +{
> +       "reference tracking: release user key reference without check",
> +       .insns = {
> +       BPF_MOV64_IMM(BPF_REG_1, -3),
> +       BPF_MOV64_IMM(BPF_REG_2, 0),
> +       BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
> +       BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
> +       BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
> +       BPF_MOV64_IMM(BPF_REG_0, 0),
> +       BPF_EXIT_INSN(),
> +       },
> +       .prog_type = BPF_PROG_TYPE_LSM,
> +       .kfunc = "bpf",
> +       .expected_attach_type = BPF_LSM_MAC,
> +       .flags = BPF_F_SLEEPABLE,
> +       .errstr = "arg#0 pointer type STRUCT bpf_key must point to scalar, or struct with scalar",
> +       .fixup_kfunc_btf_id = {
> +               { "bpf_lookup_user_key", 2 },
> +               { "bpf_key_put", 4 },
> +       },
> +       .result = REJECT,
> +},
> +{
> +       "reference tracking: release system key reference without check",
> +       .insns = {
> +       BPF_MOV64_IMM(BPF_REG_1, 1),
> +       BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
> +       BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
> +       BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
> +       BPF_MOV64_IMM(BPF_REG_0, 0),
> +       BPF_EXIT_INSN(),
> +       },
> +       .prog_type = BPF_PROG_TYPE_LSM,
> +       .kfunc = "bpf",
> +       .expected_attach_type = BPF_LSM_MAC,
> +       .flags = BPF_F_SLEEPABLE,
> +       .errstr = "arg#0 pointer type STRUCT bpf_key must point to scalar, or struct with scalar",
> +       .fixup_kfunc_btf_id = {
> +               { "bpf_lookup_system_key", 1 },
> +               { "bpf_key_put", 3 },
> +       },
> +       .result = REJECT,
> +},
> +{
> +       "reference tracking: release with NULL key pointer",
> +       .insns = {
> +       BPF_MOV64_IMM(BPF_REG_1, 0),
> +       BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
> +       BPF_MOV64_IMM(BPF_REG_0, 0),
> +       BPF_EXIT_INSN(),
> +       },
> +       .prog_type = BPF_PROG_TYPE_LSM,
> +       .kfunc = "bpf",
> +       .expected_attach_type = BPF_LSM_MAC,
> +       .flags = BPF_F_SLEEPABLE,
> +       .errstr = "arg#0 pointer type STRUCT bpf_key must point to scalar, or struct with scalar",
> +       .fixup_kfunc_btf_id = {
> +               { "bpf_key_put", 1 },
> +       },
> +       .result = REJECT,
> +},
> +{
> +       "reference tracking: leak potential reference to user key",
> +       .insns = {
> +       BPF_MOV64_IMM(BPF_REG_1, -3),
> +       BPF_MOV64_IMM(BPF_REG_2, 0),
> +       BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
> +       BPF_EXIT_INSN(),
> +       },
> +       .prog_type = BPF_PROG_TYPE_LSM,
> +       .kfunc = "bpf",
> +       .expected_attach_type = BPF_LSM_MAC,
> +       .flags = BPF_F_SLEEPABLE,
> +       .errstr = "Unreleased reference",
> +       .fixup_kfunc_btf_id = {
> +               { "bpf_lookup_user_key", 2 },
> +       },
> +       .result = REJECT,
> +},
> +{
> +       "reference tracking: leak potential reference to system key",
> +       .insns = {
> +       BPF_MOV64_IMM(BPF_REG_1, 1),
> +       BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
> +       BPF_EXIT_INSN(),
> +       },
> +       .prog_type = BPF_PROG_TYPE_LSM,
> +       .kfunc = "bpf",
> +       .expected_attach_type = BPF_LSM_MAC,
> +       .flags = BPF_F_SLEEPABLE,
> +       .errstr = "Unreleased reference",
> +       .fixup_kfunc_btf_id = {
> +               { "bpf_lookup_system_key", 1 },
> +       },
> +       .result = REJECT,
> +},
>  {
>         "reference tracking: release reference without check",
>         .insns = {
> --
> 2.25.1
>