selftests/bpf: Add selftests for bpf_task_from_pid()

Add some selftest testcases that validate the expected behavior of the
bpf_task_from_pid() kfunc that was added in the prior patch.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20221122145300.251210-3-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/prog_tests/task_kfunc.c b/tools/testing/selftests/bpf/prog_tests/task_kfunc.c
index 4994fe6092ccafee8707e08f36fe05f3bf337266..ffd8ef4303c83e5092c38f2dab5f3ea774b659d1 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/task_kfunc.c
+++ b/tools/testing/selftests/bpf/prog_tests/task_kfunc.c
@@ -78,6 +78,9 @@ static const char * const success_tests[] = {
        "test_task_xchg_release",
        "test_task_get_release",
        "test_task_current_acquire_release",
+       "test_task_from_pid_arg",
+       "test_task_from_pid_current",
+       "test_task_from_pid_invalid",
 };
 
 static struct {
@@ -99,6 +102,7 @@ static struct {
        {"task_kfunc_release_fp", "arg#0 pointer type STRUCT task_struct must point"},
        {"task_kfunc_release_null", "arg#0 is ptr_or_null_ expected ptr_ or socket"},
        {"task_kfunc_release_unacquired", "release kernel function bpf_task_release expects"},
+       {"task_kfunc_from_pid_no_null_check", "arg#0 is ptr_or_null_ expected ptr_ or socket"},
 };
 
 static void verify_fail(const char *prog_name, const char *expected_err_msg)

diff --git a/tools/testing/selftests/bpf/progs/task_kfunc_common.h b/tools/testing/selftests/bpf/progs/task_kfunc_common.h
index 160d6dde00be187bbe415a4c3e5083d163b86da6..c0ffd171743edb251cde593f250d8faf92a41c82 100644 (file)
--- a/tools/testing/selftests/bpf/progs/task_kfunc_common.h
+++ b/tools/testing/selftests/bpf/progs/task_kfunc_common.h
@@ -23,6 +23,7 @@ struct hash_map {
 struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym;
 struct task_struct *bpf_task_kptr_get(struct task_struct **pp) __ksym;
 void bpf_task_release(struct task_struct *p) __ksym;
+struct task_struct *bpf_task_from_pid(s32 pid) __ksym;
 
 static inline struct __tasks_kfunc_map_value *tasks_kfunc_map_value_lookup(struct task_struct *p)
 {

diff --git a/tools/testing/selftests/bpf/progs/task_kfunc_failure.c b/tools/testing/selftests/bpf/progs/task_kfunc_failure.c
index 93e934ddfcb66db201aced193678f628c80c6bec..e310473190d5e82707968085d739ea8eb509960c 100644 (file)
--- a/tools/testing/selftests/bpf/progs/task_kfunc_failure.c
+++ b/tools/testing/selftests/bpf/progs/task_kfunc_failure.c
@@ -258,3 +258,16 @@ int BPF_PROG(task_kfunc_release_unacquired, struct task_struct *task, u64 clone_
 
        return 0;
 }
+
+SEC("tp_btf/task_newtask")
+int BPF_PROG(task_kfunc_from_pid_no_null_check, struct task_struct *task, u64 clone_flags)
+{
+       struct task_struct *acquired;
+
+       acquired = bpf_task_from_pid(task->pid);
+
+       /* Releasing bpf_task_from_pid() lookup without a NULL check. */
+       bpf_task_release(acquired);
+
+       return 0;
+}

diff --git a/tools/testing/selftests/bpf/progs/task_kfunc_success.c b/tools/testing/selftests/bpf/progs/task_kfunc_success.c
index be4534b5ba2ea501ab73ed49903005fa3e87b549..60c7ead41cfcb6fead3ae0426851bb9b9db4d559 100644 (file)
--- a/tools/testing/selftests/bpf/progs/task_kfunc_success.c
+++ b/tools/testing/selftests/bpf/progs/task_kfunc_success.c
@@ -147,3 +147,76 @@ int BPF_PROG(test_task_current_acquire_release, struct task_struct *task, u64 cl
 
        return 0;
 }
+
+static void lookup_compare_pid(const struct task_struct *p)
+{
+       struct task_struct *acquired;
+
+       acquired = bpf_task_from_pid(p->pid);
+       if (!acquired) {
+               err = 1;
+               return;
+       }
+
+       if (acquired->pid != p->pid)
+               err = 2;
+       bpf_task_release(acquired);
+}
+
+SEC("tp_btf/task_newtask")
+int BPF_PROG(test_task_from_pid_arg, struct task_struct *task, u64 clone_flags)
+{
+       struct task_struct *acquired;
+
+       if (!is_test_kfunc_task())
+               return 0;
+
+       lookup_compare_pid(task);
+       return 0;
+}
+
+SEC("tp_btf/task_newtask")
+int BPF_PROG(test_task_from_pid_current, struct task_struct *task, u64 clone_flags)
+{
+       struct task_struct *current, *acquired;
+
+       if (!is_test_kfunc_task())
+               return 0;
+
+       lookup_compare_pid(bpf_get_current_task_btf());
+       return 0;
+}
+
+static int is_pid_lookup_valid(s32 pid)
+{
+       struct task_struct *acquired;
+
+       acquired = bpf_task_from_pid(pid);
+       if (acquired) {
+               bpf_task_release(acquired);
+               return 1;
+       }
+
+       return 0;
+}
+
+SEC("tp_btf/task_newtask")
+int BPF_PROG(test_task_from_pid_invalid, struct task_struct *task, u64 clone_flags)
+{
+       struct task_struct *acquired;
+
+       if (!is_test_kfunc_task())
+               return 0;
+
+       if (is_pid_lookup_valid(-1)) {
+               err = 1;
+               return 0;
+       }
+
+       if (is_pid_lookup_valid(0xcafef00d)) {
+               err = 2;
+               return 0;
+       }
+
+       return 0;
+}