selftests/bpf: Add tests for bpf_copy_from_user_task_str

This adds tests for both the happy path and the
error path (with and without the BPF_F_PAD_ZEROS flag).

Signed-off-by: Jordan Rome <linux@jordanrome.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250213152125.1837400-3-linux@jordanrome.com

diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
index 6f1bfacd7375372d6c610ba8145d3d840e171982..add4a18c33bdb2f4ce5eea495d25cd0b81c168cf 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
+++ b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
@@ -323,19 +323,87 @@ static void test_task_pidfd(void)
 static void test_task_sleepable(void)
 {
        struct bpf_iter_tasks *skel;
+       int pid, status, err, data_pipe[2], finish_pipe[2], c;
+       char *test_data = NULL;
+       char *test_data_long = NULL;
+       char *data[2];
+
+       if (!ASSERT_OK(pipe(data_pipe), "data_pipe") ||
+           !ASSERT_OK(pipe(finish_pipe), "finish_pipe"))
+               return;
 
        skel = bpf_iter_tasks__open_and_load();
        if (!ASSERT_OK_PTR(skel, "bpf_iter_tasks__open_and_load"))
                return;
 
+       pid = fork();
+       if (!ASSERT_GE(pid, 0, "fork"))
+               return;
+
+       if (pid == 0) {
+               /* child */
+               close(data_pipe[0]);
+               close(finish_pipe[1]);
+
+               test_data = malloc(sizeof(char) * 10);
+               strncpy(test_data, "test_data", 10);
+               test_data[9] = '\0';
+
+               test_data_long = malloc(sizeof(char) * 5000);
+               for (int i = 0; i < 5000; ++i) {
+                       if (i % 2 == 0)
+                               test_data_long[i] = 'b';
+                       else
+                               test_data_long[i] = 'a';
+               }
+               test_data_long[4999] = '\0';
+
+               data[0] = test_data;
+               data[1] = test_data_long;
+
+               write(data_pipe[1], &data, sizeof(data));
+
+               /* keep child alive until after the test */
+               err = read(finish_pipe[0], &c, 1);
+               if (err != 1)
+                       exit(-1);
+
+               close(data_pipe[1]);
+               close(finish_pipe[0]);
+               _exit(0);
+       }
+
+       /* parent */
+       close(data_pipe[1]);
+       close(finish_pipe[0]);
+
+       err = read(data_pipe[0], &data, sizeof(data));
+       ASSERT_EQ(err, sizeof(data), "read_check");
+
+       skel->bss->user_ptr = data[0];
+       skel->bss->user_ptr_long = data[1];
+       skel->bss->pid = pid;
+
        do_dummy_read(skel->progs.dump_task_sleepable);
 
        ASSERT_GT(skel->bss->num_expected_failure_copy_from_user_task, 0,
                  "num_expected_failure_copy_from_user_task");
        ASSERT_GT(skel->bss->num_success_copy_from_user_task, 0,
                  "num_success_copy_from_user_task");
+       ASSERT_GT(skel->bss->num_expected_failure_copy_from_user_task_str, 0,
+                 "num_expected_failure_copy_from_user_task_str");
+       ASSERT_GT(skel->bss->num_success_copy_from_user_task_str, 0,
+                 "num_success_copy_from_user_task_str");
 
        bpf_iter_tasks__destroy(skel);
+
+       write(finish_pipe[1], &c, 1);
+       err = waitpid(pid, &status, 0);
+       ASSERT_EQ(err, pid, "waitpid");
+       ASSERT_EQ(status, 0, "zero_child_exit");
+
+       close(data_pipe[0]);
+       close(finish_pipe[1]);
 }
 
 static void test_task_stack(void)

diff --git a/tools/testing/selftests/bpf/prog_tests/read_vsyscall.c b/tools/testing/selftests/bpf/prog_tests/read_vsyscall.c
index c7b9ba8b1d060a7ede3a669dc33cd747cb94d069..a8d1eaa670206fe08684fc0872b4beba71104eb3 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/read_vsyscall.c
+++ b/tools/testing/selftests/bpf/prog_tests/read_vsyscall.c
@@ -24,6 +24,7 @@ struct read_ret_desc {
        { .name = "copy_from_user", .ret = -EFAULT },
        { .name = "copy_from_user_task", .ret = -EFAULT },
        { .name = "copy_from_user_str", .ret = -EFAULT },
+       { .name = "copy_from_user_task_str", .ret = -EFAULT },
 };
 
 void test_read_vsyscall(void)

diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_tasks.c b/tools/testing/selftests/bpf/progs/bpf_iter_tasks.c
index bc10c4e4b4fa0e75620675ebfc934356eed3cd35..966ee5a7b066da3ce88b0fbd683a88b24efe5a89 100644 (file)
--- a/tools/testing/selftests/bpf/progs/bpf_iter_tasks.c
+++ b/tools/testing/selftests/bpf/progs/bpf_iter_tasks.c
@@ -9,6 +9,13 @@ char _license[] SEC("license") = "GPL";
 uint32_t tid = 0;
 int num_unknown_tid = 0;
 int num_known_tid = 0;
+void *user_ptr = 0;
+void *user_ptr_long = 0;
+uint32_t pid = 0;
+
+static char big_str1[5000];
+static char big_str2[5005];
+static char big_str3[4996];
 
 SEC("iter/task")
 int dump_task(struct bpf_iter__task *ctx)
@@ -35,7 +42,9 @@ int dump_task(struct bpf_iter__task *ctx)
 }
 
 int num_expected_failure_copy_from_user_task = 0;
+int num_expected_failure_copy_from_user_task_str = 0;
 int num_success_copy_from_user_task = 0;
+int num_success_copy_from_user_task_str = 0;
 
 SEC("iter.s/task")
 int dump_task_sleepable(struct bpf_iter__task *ctx)
@@ -44,6 +53,9 @@ int dump_task_sleepable(struct bpf_iter__task *ctx)
        struct task_struct *task = ctx->task;
        static const char info[] = "    === END ===";
        struct pt_regs *regs;
+       char task_str1[10] = "aaaaaaaaaa";
+       char task_str2[10], task_str3[10];
+       char task_str4[20] = "aaaaaaaaaaaaaaaaaaaa";
        void *ptr;
        uint32_t user_data = 0;
        int ret;
@@ -78,8 +90,106 @@ int dump_task_sleepable(struct bpf_iter__task *ctx)
                BPF_SEQ_PRINTF(seq, "%s\n", info);
                return 0;
        }
+
        ++num_success_copy_from_user_task;
 
+       /* Read an invalid pointer and ensure we get an error */
+       ptr = NULL;
+       ret = bpf_copy_from_user_task_str((char *)task_str1, sizeof(task_str1), ptr, task, 0);
+       if (ret >= 0 || task_str1[9] != 'a' || task_str1[0] != '\0') {
+               BPF_SEQ_PRINTF(seq, "%s\n", info);
+               return 0;
+       }
+
+       /* Read an invalid pointer and ensure we get error with pad zeros flag */
+       ptr = NULL;
+       ret = bpf_copy_from_user_task_str((char *)task_str1, sizeof(task_str1),
+                                         ptr, task, BPF_F_PAD_ZEROS);
+       if (ret >= 0 || task_str1[9] != '\0' || task_str1[0] != '\0') {
+               BPF_SEQ_PRINTF(seq, "%s\n", info);
+               return 0;
+       }
+
+       ++num_expected_failure_copy_from_user_task_str;
+
+       /* Same length as the string */
+       ret = bpf_copy_from_user_task_str((char *)task_str2, 10, user_ptr, task, 0);
+       /* only need to do the task pid check once */
+       if (bpf_strncmp(task_str2, 10, "test_data\0") != 0 || ret != 10 || task->tgid != pid) {
+               BPF_SEQ_PRINTF(seq, "%s\n", info);
+               return 0;
+       }
+
+       /* Shorter length than the string */
+       ret = bpf_copy_from_user_task_str((char *)task_str3, 2, user_ptr, task, 0);
+       if (bpf_strncmp(task_str3, 2, "t\0") != 0 || ret != 2) {
+               BPF_SEQ_PRINTF(seq, "%s\n", info);
+               return 0;
+       }
+
+       /* Longer length than the string */
+       ret = bpf_copy_from_user_task_str((char *)task_str4, 20, user_ptr, task, 0);
+       if (bpf_strncmp(task_str4, 10, "test_data\0") != 0 || ret != 10
+           || task_str4[sizeof(task_str4) - 1] != 'a') {
+               BPF_SEQ_PRINTF(seq, "%s\n", info);
+               return 0;
+       }
+
+       /* Longer length than the string with pad zeros flag */
+       ret = bpf_copy_from_user_task_str((char *)task_str4, 20, user_ptr, task, BPF_F_PAD_ZEROS);
+       if (bpf_strncmp(task_str4, 10, "test_data\0") != 0 || ret != 10
+           || task_str4[sizeof(task_str4) - 1] != '\0') {
+               BPF_SEQ_PRINTF(seq, "%s\n", info);
+               return 0;
+       }
+
+       /* Longer length than the string past a page boundary */
+       ret = bpf_copy_from_user_task_str(big_str1, 5000, user_ptr, task, 0);
+       if (bpf_strncmp(big_str1, 10, "test_data\0") != 0 || ret != 10) {
+               BPF_SEQ_PRINTF(seq, "%s\n", info);
+               return 0;
+       }
+
+       /* String that crosses a page boundary */
+       ret = bpf_copy_from_user_task_str(big_str1, 5000, user_ptr_long, task, BPF_F_PAD_ZEROS);
+       if (bpf_strncmp(big_str1, 4, "baba") != 0 || ret != 5000
+           || bpf_strncmp(big_str1 + 4996, 4, "bab\0") != 0) {
+               BPF_SEQ_PRINTF(seq, "%s\n", info);
+               return 0;
+       }
+
+       for (int i = 0; i < 4999; ++i) {
+               if (i % 2 == 0) {
+                       if (big_str1[i] != 'b') {
+                               BPF_SEQ_PRINTF(seq, "%s\n", info);
+                               return 0;
+                       }
+               } else {
+                       if (big_str1[i] != 'a') {
+                               BPF_SEQ_PRINTF(seq, "%s\n", info);
+                               return 0;
+                       }
+               }
+       }
+
+       /* Longer length than the string that crosses a page boundary */
+       ret = bpf_copy_from_user_task_str(big_str2, 5005, user_ptr_long, task, BPF_F_PAD_ZEROS);
+       if (bpf_strncmp(big_str2, 4, "baba") != 0 || ret != 5000
+           || bpf_strncmp(big_str2 + 4996, 5, "bab\0\0") != 0) {
+               BPF_SEQ_PRINTF(seq, "%s\n", info);
+               return 0;
+       }
+
+       /* Shorter length than the string that crosses a page boundary */
+       ret = bpf_copy_from_user_task_str(big_str3, 4996, user_ptr_long, task, 0);
+       if (bpf_strncmp(big_str3, 4, "baba") != 0 || ret != 4996
+           || bpf_strncmp(big_str3 + 4992, 4, "bab\0") != 0) {
+               BPF_SEQ_PRINTF(seq, "%s\n", info);
+               return 0;
+       }
+
+       ++num_success_copy_from_user_task_str;
+
        if (ctx->meta->seq_num == 0)
                BPF_SEQ_PRINTF(seq, "    tgid      gid     data\n");
 

diff --git a/tools/testing/selftests/bpf/progs/read_vsyscall.c b/tools/testing/selftests/bpf/progs/read_vsyscall.c
index 39ebef4300593d816026164444499080b6cd7a96..395591374d4fa190057f9c6ebb6e56536bbc4033 100644 (file)
--- a/tools/testing/selftests/bpf/progs/read_vsyscall.c
+++ b/tools/testing/selftests/bpf/progs/read_vsyscall.c
@@ -8,14 +8,16 @@
 
 int target_pid = 0;
 void *user_ptr = 0;
-int read_ret[9];
+int read_ret[10];
 
 char _license[] SEC("license") = "GPL";
 
 /*
- * This is the only kfunc, the others are helpers
+ * These are the kfuncs, the others are helpers
  */
 int bpf_copy_from_user_str(void *dst, u32, const void *, u64) __weak __ksym;
+int bpf_copy_from_user_task_str(void *dst, u32, const void *,
+                               struct task_struct *, u64) __weak __ksym;
 
 SEC("fentry/" SYS_PREFIX "sys_nanosleep")
 int do_probe_read(void *ctx)
@@ -47,6 +49,11 @@ int do_copy_from_user(void *ctx)
        read_ret[7] = bpf_copy_from_user_task(buf, sizeof(buf), user_ptr,
                                              bpf_get_current_task_btf(), 0);
        read_ret[8] = bpf_copy_from_user_str((char *)buf, sizeof(buf), user_ptr, 0);
+       read_ret[9] = bpf_copy_from_user_task_str((char *)buf,
+                                                 sizeof(buf),
+                                                 user_ptr,
+                                                 bpf_get_current_task_btf(),
+                                                 0);
 
        return 0;
 }