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Fri, 13 Dec 2024 15:30:05 -0800 (PST) Received: from n36-183-057.byted.org ([130.44.215.64]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7b7047d4a20sm25805085a.39.2024.12.13.15.30.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Dec 2024 15:30:04 -0800 (PST) From: Amery Hung To: netdev@vger.kernel.org Cc: bpf@vger.kernel.org, daniel@iogearbox.net, andrii@kernel.org, alexei.starovoitov@gmail.com, martin.lau@kernel.org, sinquersw@gmail.com, toke@redhat.com, jhs@mojatatu.com, jiri@resnulli.us, stfomichev@gmail.com, ekarani.silvestre@ccc.ufcg.edu.br, yangpeihao@sjtu.edu.cn, xiyou.wangcong@gmail.com, yepeilin.cs@gmail.com, ameryhung@gmail.com Subject: [PATCH bpf-next v1 04/13] selftests/bpf: Test returning referenced kptr from struct_ops programs Date: Fri, 13 Dec 2024 23:29:49 +0000 Message-Id: <20241213232958.2388301-5-amery.hung@bytedance.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20241213232958.2388301-1-amery.hung@bytedance.com> References: <20241213232958.2388301-1-amery.hung@bytedance.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net Test struct_ops programs returning referenced kptr. When the return type of a struct_ops operator is pointer to struct, the verifier should only allow programs that return a scalar NULL or a non-local kptr with the correct type in its unmodified form. Signed-off-by: Amery Hung --- .../selftests/bpf/bpf_testmod/bpf_testmod.c | 8 ++ .../selftests/bpf/bpf_testmod/bpf_testmod.h | 4 + .../prog_tests/test_struct_ops_kptr_return.c | 87 +++++++++++++++++++ .../bpf/progs/struct_ops_kptr_return.c | 29 +++++++ ...uct_ops_kptr_return_fail__invalid_scalar.c | 24 +++++ .../struct_ops_kptr_return_fail__local_kptr.c | 30 +++++++ ...uct_ops_kptr_return_fail__nonzero_offset.c | 23 +++++ .../struct_ops_kptr_return_fail__wrong_type.c | 28 ++++++ 8 files changed, 233 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/test_struct_ops_kptr_return.c create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_kptr_return.c create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__invalid_scalar.c create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__local_kptr.c create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__nonzero_offset.c create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__wrong_type.c diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c index 244234546ae2..cfab09f16cc2 100644 --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c @@ -1141,11 +1141,19 @@ static int bpf_testmod_ops__test_refcounted(int dummy, return 0; } +static struct task_struct * +bpf_testmod_ops__test_return_ref_kptr(int dummy, struct task_struct *task__ref, + struct cgroup *cgrp) +{ + return NULL; +} + static struct bpf_testmod_ops __bpf_testmod_ops = { .test_1 = bpf_testmod_test_1, .test_2 = bpf_testmod_test_2, .test_maybe_null = bpf_testmod_ops__test_maybe_null, .test_refcounted = bpf_testmod_ops__test_refcounted, + .test_return_ref_kptr = bpf_testmod_ops__test_return_ref_kptr, }; struct bpf_struct_ops bpf_bpf_testmod_ops = { diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h index 0e31586c1353..a66659314e67 100644 --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h @@ -6,6 +6,7 @@ #include struct task_struct; +struct cgroup; struct bpf_testmod_test_read_ctx { char *buf; @@ -38,6 +39,9 @@ struct bpf_testmod_ops { int (*unsupported_ops)(void); /* Used to test ref_acquired arguments. */ int (*test_refcounted)(int dummy, struct task_struct *task); + /* Used to test returning referenced kptr. */ + struct task_struct *(*test_return_ref_kptr)(int dummy, struct task_struct *task, + struct cgroup *cgrp); /* The following fields are used to test shadow copies. */ char onebyte; diff --git a/tools/testing/selftests/bpf/prog_tests/test_struct_ops_kptr_return.c b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_kptr_return.c new file mode 100644 index 000000000000..bc2fac39215a --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_kptr_return.c @@ -0,0 +1,87 @@ +#include + +#include "struct_ops_kptr_return.skel.h" +#include "struct_ops_kptr_return_fail__wrong_type.skel.h" +#include "struct_ops_kptr_return_fail__invalid_scalar.skel.h" +#include "struct_ops_kptr_return_fail__nonzero_offset.skel.h" +#include "struct_ops_kptr_return_fail__local_kptr.skel.h" + +/* Test that the verifier accepts a program that acquires a referenced + * kptr and releases the reference through return + */ +static void kptr_return(void) +{ + struct struct_ops_kptr_return *skel; + + skel = struct_ops_kptr_return__open_and_load(); + if (!ASSERT_OK_PTR(skel, "struct_ops_module_open_and_load")) + return; + + struct_ops_kptr_return__destroy(skel); +} + +/* Test that the verifier rejects a program that returns a kptr of the + * wrong type + */ +static void kptr_return_fail__wrong_type(void) +{ + struct struct_ops_kptr_return_fail__wrong_type *skel; + + skel = struct_ops_kptr_return_fail__wrong_type__open_and_load(); + if (ASSERT_ERR_PTR(skel, "struct_ops_module_fail__wrong_type__open_and_load")) + return; + + struct_ops_kptr_return_fail__wrong_type__destroy(skel); +} + +/* Test that the verifier rejects a program that returns a non-null scalar */ +static void kptr_return_fail__invalid_scalar(void) +{ + struct struct_ops_kptr_return_fail__invalid_scalar *skel; + + skel = struct_ops_kptr_return_fail__invalid_scalar__open_and_load(); + if (ASSERT_ERR_PTR(skel, "struct_ops_module_fail__invalid_scalar__open_and_load")) + return; + + struct_ops_kptr_return_fail__invalid_scalar__destroy(skel); +} + +/* Test that the verifier rejects a program that returns kptr with non-zero offset */ +static void kptr_return_fail__nonzero_offset(void) +{ + struct struct_ops_kptr_return_fail__nonzero_offset *skel; + + skel = struct_ops_kptr_return_fail__nonzero_offset__open_and_load(); + if (ASSERT_ERR_PTR(skel, "struct_ops_module_fail__nonzero_offset__open_and_load")) + return; + + struct_ops_kptr_return_fail__nonzero_offset__destroy(skel); +} + +/* Test that the verifier rejects a program that returns local kptr */ +static void kptr_return_fail__local_kptr(void) +{ + struct struct_ops_kptr_return_fail__local_kptr *skel; + + skel = struct_ops_kptr_return_fail__local_kptr__open_and_load(); + if (ASSERT_ERR_PTR(skel, "struct_ops_module_fail__local_kptr__open_and_load")) + return; + + struct_ops_kptr_return_fail__local_kptr__destroy(skel); +} + +void test_struct_ops_kptr_return(void) +{ + if (test__start_subtest("kptr_return")) + kptr_return(); + if (test__start_subtest("kptr_return_fail__wrong_type")) + kptr_return_fail__wrong_type(); + if (test__start_subtest("kptr_return_fail__invalid_scalar")) + kptr_return_fail__invalid_scalar(); + if (test__start_subtest("kptr_return_fail__nonzero_offset")) + kptr_return_fail__nonzero_offset(); + if (test__start_subtest("kptr_return_fail__local_kptr")) + kptr_return_fail__local_kptr(); +} + + diff --git a/tools/testing/selftests/bpf/progs/struct_ops_kptr_return.c b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return.c new file mode 100644 index 000000000000..29b7719cd4c9 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return.c @@ -0,0 +1,29 @@ +#include +#include +#include "../bpf_testmod/bpf_testmod.h" + +char _license[] SEC("license") = "GPL"; + +void bpf_task_release(struct task_struct *p) __ksym; + +/* This test struct_ops BPF programs returning referenced kptr. The verifier should + * allow a referenced kptr or a NULL pointer to be returned. A referenced kptr to task + * here is acquried automatically as the task argument is tagged with "__ref". + */ +SEC("struct_ops/test_return_ref_kptr") +struct task_struct *BPF_PROG(test_return_ref_kptr, int dummy, + struct task_struct *task, struct cgroup *cgrp) +{ + if (dummy % 2) { + bpf_task_release(task); + return NULL; + } + return task; +} + +SEC(".struct_ops.link") +struct bpf_testmod_ops testmod_kptr_return = { + .test_return_ref_kptr = (void *)test_return_ref_kptr, +}; + + diff --git a/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__invalid_scalar.c b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__invalid_scalar.c new file mode 100644 index 000000000000..d67982ba8224 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__invalid_scalar.c @@ -0,0 +1,24 @@ +#include +#include +#include "../bpf_testmod/bpf_testmod.h" + +char _license[] SEC("license") = "GPL"; + +struct cgroup *bpf_cgroup_acquire(struct cgroup *p) __ksym; +void bpf_task_release(struct task_struct *p) __ksym; + +/* This test struct_ops BPF programs returning referenced kptr. The verifier should + * reject programs returning a non-zero scalar value. + */ +SEC("struct_ops/test_return_ref_kptr") +struct task_struct *BPF_PROG(test_return_ref_kptr, int dummy, + struct task_struct *task, struct cgroup *cgrp) +{ + bpf_task_release(task); + return (struct task_struct *)1; +} + +SEC(".struct_ops.link") +struct bpf_testmod_ops testmod_kptr_return = { + .test_return_ref_kptr = (void *)test_return_ref_kptr, +}; diff --git a/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__local_kptr.c b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__local_kptr.c new file mode 100644 index 000000000000..9a4247432539 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__local_kptr.c @@ -0,0 +1,30 @@ +#include +#include +#include "../bpf_testmod/bpf_testmod.h" +#include "bpf_experimental.h" + +char _license[] SEC("license") = "GPL"; + +struct cgroup *bpf_cgroup_acquire(struct cgroup *p) __ksym; +void bpf_task_release(struct task_struct *p) __ksym; + +/* This test struct_ops BPF programs returning referenced kptr. The verifier should + * reject programs returning a local kptr. + */ +SEC("struct_ops/test_return_ref_kptr") +struct task_struct *BPF_PROG(test_return_ref_kptr, int dummy, + struct task_struct *task, struct cgroup *cgrp) +{ + struct task_struct *t; + + t = bpf_obj_new(typeof(*task)); + if (!t) + return task; + + return t; +} + +SEC(".struct_ops.link") +struct bpf_testmod_ops testmod_kptr_return = { + .test_return_ref_kptr = (void *)test_return_ref_kptr, +}; diff --git a/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__nonzero_offset.c b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__nonzero_offset.c new file mode 100644 index 000000000000..5bb0b4029d11 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__nonzero_offset.c @@ -0,0 +1,23 @@ +#include +#include +#include "../bpf_testmod/bpf_testmod.h" + +char _license[] SEC("license") = "GPL"; + +struct cgroup *bpf_cgroup_acquire(struct cgroup *p) __ksym; +void bpf_task_release(struct task_struct *p) __ksym; + +/* This test struct_ops BPF programs returning referenced kptr. The verifier should + * reject programs returning a modified referenced kptr. + */ +SEC("struct_ops/test_return_ref_kptr") +struct task_struct *BPF_PROG(test_return_ref_kptr, int dummy, + struct task_struct *task, struct cgroup *cgrp) +{ + return (struct task_struct *)&task->jobctl; +} + +SEC(".struct_ops.link") +struct bpf_testmod_ops testmod_kptr_return = { + .test_return_ref_kptr = (void *)test_return_ref_kptr, +}; diff --git a/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__wrong_type.c b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__wrong_type.c new file mode 100644 index 000000000000..32365cb7af49 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__wrong_type.c @@ -0,0 +1,28 @@ +#include +#include +#include "../bpf_testmod/bpf_testmod.h" + +char _license[] SEC("license") = "GPL"; + +struct cgroup *bpf_cgroup_acquire(struct cgroup *p) __ksym; +void bpf_task_release(struct task_struct *p) __ksym; + +/* This test struct_ops BPF programs returning referenced kptr. The verifier should + * reject programs returning a referenced kptr of the wrong type. + */ +SEC("struct_ops/test_return_ref_kptr") +struct task_struct *BPF_PROG(test_return_ref_kptr, int dummy, + struct task_struct *task, struct cgroup *cgrp) +{ + struct task_struct *ret; + + ret = (struct task_struct *)bpf_cgroup_acquire(cgrp); + bpf_task_release(task); + + return ret; +} + +SEC(".struct_ops.link") +struct bpf_testmod_ops testmod_kptr_return = { + .test_return_ref_kptr = (void *)test_return_ref_kptr, +};