[bpf-next v2 2/2] selftests/bpf: Add tests for bpf_copy_from_user_task_str

[Jordan Rome <linux@jordanrome.com>]

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>
---
 .../selftests/bpf/prog_tests/bpf_iter.c       |  7 +++
 .../selftests/bpf/prog_tests/read_vsyscall.c  |  1 +
 .../selftests/bpf/progs/bpf_iter_tasks.c      | 55 +++++++++++++++++++
 .../selftests/bpf/progs/read_vsyscall.c       |  6 +-
 4 files changed, 67 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
index 6f1bfacd7375..8ed864793bd1 100644
--- a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
+++ b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
@@ -34,6 +34,8 @@
 #include "bpf_iter_ksym.skel.h"
 #include "bpf_iter_sockmap.skel.h"

+static char test_data[] = "test_data";
+
 static void test_btf_id_or_null(void)
 {
 	struct bpf_iter_test_kern3 *skel;
@@ -328,12 +330,17 @@ static void test_task_sleepable(void)
 	if (!ASSERT_OK_PTR(skel, "bpf_iter_tasks__open_and_load"))
 		return;

+	skel->bss->user_ptr = test_data;
 	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);
 }
diff --git a/tools/testing/selftests/bpf/prog_tests/read_vsyscall.c b/tools/testing/selftests/bpf/prog_tests/read_vsyscall.c
index c7b9ba8b1d06..a8d1eaa67020 100644
--- 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 bc10c4e4b4fa..90691e34b915 100644
--- a/tools/testing/selftests/bpf/progs/bpf_iter_tasks.c
+++ b/tools/testing/selftests/bpf/progs/bpf_iter_tasks.c
@@ -9,6 +9,7 @@ char _license[] SEC("license") = "GPL";
 uint32_t tid = 0;
 int num_unknown_tid = 0;
 int num_known_tid = 0;
+void *user_ptr = 0;

 SEC("iter/task")
 int dump_task(struct bpf_iter__task *ctx)
@@ -35,7 +36,9 @@ 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 +47,9 @@ 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 +84,57 @@ 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') {
+		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') {
+		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);
+	if (bpf_strncmp(task_str2, 10, "test_data\0") != 0 || ret != 10) {
+		BPF_SEQ_PRINTF(seq, "%s\n", info);
+		return 0;
+	}
+
+	/* Shorter length than the string */
+	ret = bpf_copy_from_user_task_str((char *)task_str3, 9, user_ptr, task, 0);
+	if (bpf_strncmp(task_str3, 9, "test_dat\0") != 0 || ret != 9) {
+		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;
+	}
+
+	++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 39ebef430059..623c1c5bd2d0 100644
--- a/tools/testing/selftests/bpf/progs/read_vsyscall.c
+++ b/tools/testing/selftests/bpf/progs/read_vsyscall.c
@@ -8,14 +8,15 @@

 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 +48,7 @@ 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;
 }
--
2.43.5