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[76.146.13.146]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-73265f98e18sm5039118b3a.106.2025.02.17.11.06.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 Feb 2025 11:06:55 -0800 (PST) From: Amery Hung To: bpf@vger.kernel.org Cc: daniel@iogearbox.net, andrii@kernel.org, alexei.starovoitov@gmail.com, martin.lau@kernel.org, eddyz87@gmail.com, ameryhung@gmail.com, kernel-team@meta.com Subject: [PATCH bpf-next v2 5/5] selftests/bpf: Test returning referenced kptr from struct_ops programs Date: Mon, 17 Feb 2025 11:06:40 -0800 Message-ID: <20250217190640.1748177-6-ameryhung@gmail.com> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20250217190640.1748177-1-ameryhung@gmail.com> References: <20250217190640.1748177-1-ameryhung@gmail.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 From: Amery Hung 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 Acked-by: Eduard Zingerman Acked-by: Martin KaFai Lau --- .../prog_tests/test_struct_ops_kptr_return.c | 16 +++++++++ .../bpf/progs/struct_ops_kptr_return.c | 30 ++++++++++++++++ ...uct_ops_kptr_return_fail__invalid_scalar.c | 26 ++++++++++++++ .../struct_ops_kptr_return_fail__local_kptr.c | 34 +++++++++++++++++++ ...uct_ops_kptr_return_fail__nonzero_offset.c | 25 ++++++++++++++ .../struct_ops_kptr_return_fail__wrong_type.c | 30 ++++++++++++++++ .../selftests/bpf/test_kmods/bpf_testmod.c | 8 +++++ .../selftests/bpf/test_kmods/bpf_testmod.h | 4 +++ 8 files changed, 173 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/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..467cc72a3588 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_kptr_return.c @@ -0,0 +1,16 @@ +#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" + +void test_struct_ops_kptr_return(void) +{ + RUN_TESTS(struct_ops_kptr_return); + RUN_TESTS(struct_ops_kptr_return_fail__wrong_type); + RUN_TESTS(struct_ops_kptr_return_fail__invalid_scalar); + RUN_TESTS(struct_ops_kptr_return_fail__nonzero_offset); + RUN_TESTS(struct_ops_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..36386b3c23a1 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return.c @@ -0,0 +1,30 @@ +#include +#include +#include "../test_kmods/bpf_testmod.h" +#include "bpf_misc.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(kptr_return, 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 *)kptr_return, +}; + + 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..caeea158ef69 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__invalid_scalar.c @@ -0,0 +1,26 @@ +#include +#include +#include "../test_kmods/bpf_testmod.h" +#include "bpf_misc.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") +__failure __msg("At program exit the register R0 has smin=1 smax=1 should have been in [0, 0]") +struct task_struct *BPF_PROG(kptr_return_fail__invalid_scalar, 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 *)kptr_return_fail__invalid_scalar, +}; 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..b8b4f05c3d7f --- /dev/null +++ b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__local_kptr.c @@ -0,0 +1,34 @@ +#include +#include +#include "../test_kmods/bpf_testmod.h" +#include "bpf_experimental.h" +#include "bpf_misc.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") +__failure __msg("At program exit the register R0 is not a known value (ptr_or_null_)") +struct task_struct *BPF_PROG(kptr_return_fail__local_kptr, int dummy, + struct task_struct *task, struct cgroup *cgrp) +{ + struct task_struct *t; + + bpf_task_release(task); + + t = bpf_obj_new(typeof(*task)); + if (!t) + return NULL; + + return t; +} + +SEC(".struct_ops.link") +struct bpf_testmod_ops testmod_kptr_return = { + .test_return_ref_kptr = (void *)kptr_return_fail__local_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..7ddeb28c2329 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__nonzero_offset.c @@ -0,0 +1,25 @@ +#include +#include +#include "../test_kmods/bpf_testmod.h" +#include "bpf_misc.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") +__failure __msg("dereference of modified trusted_ptr_ ptr R0 off={{[0-9]+}} disallowed") +struct task_struct *BPF_PROG(kptr_return_fail__nonzero_offset, 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 *)kptr_return_fail__nonzero_offset, +}; 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..6a2dd5367802 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__wrong_type.c @@ -0,0 +1,30 @@ +#include +#include +#include "../test_kmods/bpf_testmod.h" +#include "bpf_misc.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") +__failure __msg("At program exit the register R0 is not a known value (ptr_or_null_)") +struct task_struct *BPF_PROG(kptr_return_fail__wrong_type, 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 *)kptr_return_fail__wrong_type, +}; diff --git a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c index 802cbd871035..89dc502de9d4 100644 --- a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c +++ b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c @@ -1182,11 +1182,19 @@ 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/test_kmods/bpf_testmod.h b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.h index c57b2f9dab10..c9fab51f16e2 100644 --- a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.h +++ b/tools/testing/selftests/bpf/test_kmods/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;