[PATCH v3 1/1] selftests/landlock: skip ptrace_test according to YAMA
Mickaël Salaün
mic at digikod.net
Tue Jan 3 15:56:31 UTC 2023
Please run clang-format-14 -i ptrace_test.c
On 27/12/2022 15:02, jeffxu at chromium.org wrote:
> From: Jeff Xu <jeffxu at google.com>
>
> Add check for yama setting for ptrace_test.
>
> Signed-off-by: Jeff Xu <jeffxu at google.com>
> ---
> .../testing/selftests/landlock/ptrace_test.c | 173 ++++++++++++------
> 1 file changed, 112 insertions(+), 61 deletions(-)
>
> diff --git a/tools/testing/selftests/landlock/ptrace_test.c b/tools/testing/selftests/landlock/ptrace_test.c
> index c28ef98ff3ac..0056815deef8 100644
> --- a/tools/testing/selftests/landlock/ptrace_test.c
> +++ b/tools/testing/selftests/landlock/ptrace_test.c
> @@ -60,6 +60,23 @@ static int test_ptrace_read(const pid_t pid)
> return 0;
> }
>
> +static int get_yama_ptrace_scope(void)
> +{
> + int ret = -1;
> + char buf[2] = {};
> + int fd = open("/proc/sys/kernel/yama/ptrace_scope", O_RDONLY);
> +
> + if (fd < 0)
> + return 0;
> +
> + if (read(fd, &buf, 1) < 0)
> + return -1;
> +
> + ret = atoi(buf);
> + close(fd);
> + return ret;
> +}
> +
> /* clang-format off */
> FIXTURE(hierarchy) {};
> /* clang-format on */
> @@ -69,6 +86,7 @@ FIXTURE_VARIANT(hierarchy)
> const bool domain_both;
> const bool domain_parent;
> const bool domain_child;
> + const int yama_ptrace_scope_max_supported;
This is not used anymore.
> };
>
> /*
> @@ -93,6 +111,7 @@ FIXTURE_VARIANT_ADD(hierarchy, allow_without_domain) {
> .domain_both = false,
> .domain_parent = false,
> .domain_child = false,
> + .yama_ptrace_scope_max_supported = 0,
> };
>
> /*
> @@ -110,6 +129,7 @@ FIXTURE_VARIANT_ADD(hierarchy, allow_with_one_domain) {
> .domain_both = false,
> .domain_parent = false,
> .domain_child = true,
> + .yama_ptrace_scope_max_supported = 1,
> };
>
> /*
> @@ -126,6 +146,7 @@ FIXTURE_VARIANT_ADD(hierarchy, deny_with_parent_domain) {
> .domain_both = false,
> .domain_parent = true,
> .domain_child = false,
> + .yama_ptrace_scope_max_supported = 0,
> };
>
> /*
> @@ -143,6 +164,7 @@ FIXTURE_VARIANT_ADD(hierarchy, deny_with_sibling_domain) {
> .domain_both = false,
> .domain_parent = true,
> .domain_child = true,
> + .yama_ptrace_scope_max_supported = 2,
> };
>
> /*
> @@ -160,6 +182,7 @@ FIXTURE_VARIANT_ADD(hierarchy, allow_sibling_domain) {
> .domain_both = true,
> .domain_parent = false,
> .domain_child = false,
> + .yama_ptrace_scope_max_supported = 0,
> };
>
> /*
> @@ -178,6 +201,7 @@ FIXTURE_VARIANT_ADD(hierarchy, allow_with_nested_domain) {
> .domain_both = true,
> .domain_parent = false,
> .domain_child = true,
> + .yama_ptrace_scope_max_supported = 1,
> };
>
> /*
> @@ -196,6 +220,7 @@ FIXTURE_VARIANT_ADD(hierarchy, deny_with_nested_and_parent_domain) {
> .domain_both = true,
> .domain_parent = true,
> .domain_child = false,
> + .yama_ptrace_scope_max_supported = 0,
> };
>
> /*
> @@ -216,6 +241,7 @@ FIXTURE_VARIANT_ADD(hierarchy, deny_with_forked_domain) {
> .domain_both = true,
> .domain_parent = true,
> .domain_child = true,
> + .yama_ptrace_scope_max_supported = 2,
> };
>
> FIXTURE_SETUP(hierarchy)
> @@ -232,8 +258,20 @@ TEST_F(hierarchy, trace)
> pid_t child, parent;
> int status, err_proc_read;
> int pipe_child[2], pipe_parent[2];
> + int yama_ptrace_scope;
> char buf_parent;
> long ret;
> + bool can_trace_child, can_trace_parent;
> +
> + yama_ptrace_scope = get_yama_ptrace_scope();
> + ASSERT_LE(0, yama_ptrace_scope);
> +
> + if (yama_ptrace_scope >= 3)
> + SKIP(return, "Yama forbids any ptrace use (scope %d)", yama_ptrace_scope);
> +
> + can_trace_child = !variant->domain_parent && (yama_ptrace_scope < 2);
> + can_trace_parent = !variant->domain_child && (yama_ptrace_scope < 1);
> + TH_LOG("can_trace_child:%d, can_trace_parent:%d", can_trace_child, can_trace_parent);
No need to log this because tests may already be marked as skipped.
>
> /*
> * Removes all effective and permitted capabilities to not interfere
> @@ -258,6 +296,7 @@ TEST_F(hierarchy, trace)
>
> ASSERT_EQ(0, close(pipe_parent[1]));
> ASSERT_EQ(0, close(pipe_child[0]));
> +
> if (variant->domain_child)
> create_domain(_metadata);
>
> @@ -265,43 +304,47 @@ TEST_F(hierarchy, trace)
> ASSERT_EQ(1, read(pipe_parent[0], &buf_child, 1));
>
> /* Tests PTRACE_ATTACH and PTRACE_MODE_READ on the parent. */
> - err_proc_read = test_ptrace_read(parent);
> - ret = ptrace(PTRACE_ATTACH, parent, NULL, 0);
> - if (variant->domain_child) {
You only need to replace this check with !can_trace_parent.
> - EXPECT_EQ(-1, ret);
> - EXPECT_EQ(EPERM, errno);
> - EXPECT_EQ(EACCES, err_proc_read);
> - } else {
> - EXPECT_EQ(0, ret);
> - EXPECT_EQ(0, err_proc_read);
> - }
> - if (ret == 0) {
> - ASSERT_EQ(parent, waitpid(parent, &status, 0));
> - ASSERT_EQ(1, WIFSTOPPED(status));
> - ASSERT_EQ(0, ptrace(PTRACE_DETACH, parent, NULL, 0));
> + if (can_trace_parent) {
The previous check should be enough.
> + err_proc_read = test_ptrace_read(parent);
> + ret = ptrace(PTRACE_ATTACH, parent, NULL, 0);
> + if (variant->domain_child) {
> + EXPECT_EQ(-1, ret);
> + EXPECT_EQ(EPERM, errno);
> + EXPECT_EQ(EACCES, err_proc_read);
> + } else {
> + EXPECT_EQ(0, ret);
> + EXPECT_EQ(0, err_proc_read);
> + }
> + if (ret == 0) {
> + ASSERT_EQ(parent, waitpid(parent, &status, 0));
> + ASSERT_EQ(1, WIFSTOPPED(status));
> + ASSERT_EQ(0, ptrace(PTRACE_DETACH, parent, NULL, 0));
> + }
> }
>
> /* Tests child PTRACE_TRACEME. */
> - ret = ptrace(PTRACE_TRACEME);
> - if (variant->domain_parent) {
Ditto, replace with !can_trace_child.
> - EXPECT_EQ(-1, ret);
> - EXPECT_EQ(EPERM, errno);
> - } else {
> - EXPECT_EQ(0, ret);
> + if (can_trace_child) {
The previous check should be enough.
> + ret = ptrace(PTRACE_TRACEME);
> + if (variant->domain_parent) {
> + EXPECT_EQ(-1, ret);
> + EXPECT_EQ(EPERM, errno);
> + } else {
> + EXPECT_EQ(0, ret);
> + }
> +
> + /*
> + * Signals that the PTRACE_ATTACH test is done and the
> + * PTRACE_TRACEME test is ongoing.
> + */
> + ASSERT_EQ(1, write(pipe_child[1], ".", 1));
> +
> + if (!variant->domain_parent)
> + ASSERT_EQ(0, raise(SIGSTOP));
> +
> + /* Waits for the parent PTRACE_ATTACH test. */
> + ASSERT_EQ(1, read(pipe_parent[0], &buf_child, 1));
> }
>
> - /*
> - * Signals that the PTRACE_ATTACH test is done and the
> - * PTRACE_TRACEME test is ongoing.
> - */
> - ASSERT_EQ(1, write(pipe_child[1], ".", 1));
> -
> - if (!variant->domain_parent) {
Ditto, replace with can_trace_child.
> - ASSERT_EQ(0, raise(SIGSTOP));
> - }
> -
> - /* Waits for the parent PTRACE_ATTACH test. */
> - ASSERT_EQ(1, read(pipe_parent[0], &buf_child, 1));
Should not be removed.
> _exit(_metadata->passed ? EXIT_SUCCESS : EXIT_FAILURE);
> return;
> }
> @@ -318,42 +361,50 @@ TEST_F(hierarchy, trace)
> * Waits for the child to test PTRACE_ATTACH on the parent and start
> * testing PTRACE_TRACEME.
> */
> - ASSERT_EQ(1, read(pipe_child[0], &buf_parent, 1));
> -
> - /* Tests child PTRACE_TRACEME. */
> - if (!variant->domain_parent) {
ditto
> - ASSERT_EQ(child, waitpid(child, &status, 0));
> - ASSERT_EQ(1, WIFSTOPPED(status));
> - ASSERT_EQ(0, ptrace(PTRACE_DETACH, child, NULL, 0));
> - } else {
> - /* The child should not be traced by the parent. */
> - EXPECT_EQ(-1, ptrace(PTRACE_DETACH, child, NULL, 0));
> - EXPECT_EQ(ESRCH, errno);
> - }
> + if (can_trace_child) {
> + ASSERT_EQ(1, read(pipe_child[0], &buf_parent, 1));
>
> - /* Tests PTRACE_ATTACH and PTRACE_MODE_READ on the child. */
> - err_proc_read = test_ptrace_read(child);
> - ret = ptrace(PTRACE_ATTACH, child, NULL, 0);
> - if (variant->domain_parent) {
ditto
> - EXPECT_EQ(-1, ret);
> - EXPECT_EQ(EPERM, errno);
> - EXPECT_EQ(EACCES, err_proc_read);
> - } else {
> - EXPECT_EQ(0, ret);
> - EXPECT_EQ(0, err_proc_read);
> - }
> - if (ret == 0) {
> - ASSERT_EQ(child, waitpid(child, &status, 0));
> - ASSERT_EQ(1, WIFSTOPPED(status));
> - ASSERT_EQ(0, ptrace(PTRACE_DETACH, child, NULL, 0));
> + /* Tests child PTRACE_TRACEME. */
> + if (!variant->domain_parent) {
> + ASSERT_EQ(child, waitpid(child, &status, 0));
> + ASSERT_EQ(1, WIFSTOPPED(status));
> + ASSERT_EQ(0, ptrace(PTRACE_DETACH, child, NULL, 0));
> + } else {
> + /* The child should not be traced by the parent. */
> + EXPECT_EQ(-1, ptrace(PTRACE_DETACH, child, NULL, 0));
> + EXPECT_EQ(ESRCH, errno);
> + }
> +
> + /* Tests PTRACE_ATTACH and PTRACE_MODE_READ on the child. */
> + err_proc_read = test_ptrace_read(child);
> + ret = ptrace(PTRACE_ATTACH, child, NULL, 0);
> + if (variant->domain_parent) {
> + EXPECT_EQ(-1, ret);
> + EXPECT_EQ(EPERM, errno);
> + EXPECT_EQ(EACCES, err_proc_read);
> + } else {
> + EXPECT_EQ(0, ret);
> + EXPECT_EQ(0, err_proc_read);
> + }
> + if (ret == 0) {
> + ASSERT_EQ(child, waitpid(child, &status, 0));
> + ASSERT_EQ(1, WIFSTOPPED(status));
> + ASSERT_EQ(0, ptrace(PTRACE_DETACH, child, NULL, 0));
> + }
> +
> + /* Signals that the parent PTRACE_ATTACH test is done. */
> + ASSERT_EQ(1, write(pipe_parent[1], ".", 1));
> }
>
> - /* Signals that the parent PTRACE_ATTACH test is done. */
> - ASSERT_EQ(1, write(pipe_parent[1], ".", 1));
ditto
> ASSERT_EQ(child, waitpid(child, &status, 0));
> if (WIFSIGNALED(status) || !WIFEXITED(status) ||
> WEXITSTATUS(status) != EXIT_SUCCESS)
> _metadata->passed = 0;
> +
> + if (yama_ptrace_scope > 0)
> + SKIP(return, "Incomplete tests due to Yama restrictions (ptrace_scope:%d)",
For consistency, please change to " (scope %d)"
> + yama_ptrace_scope);
> +
> }
>
> TEST_HARNESS_MAIN
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