From 366617a69e60610912836570546f118006ebc7cb Mon Sep 17 00:00:00 2001 From: Jeff Xu Date: Fri, 13 Jan 2023 05:32:29 +0000 Subject: selftests/landlock: Skip overlayfs tests when not supported MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit overlayfs may be disabled in the kernel configuration, causing related tests to fail. Check that overlayfs is supported at runtime, so we can skip layout2_overlay.* accordingly. Signed-off-by: Jeff Xu Reviewed-by: Guenter Roeck Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20230113053229.1281774-2-jeffxu@google.com [mic: Reword comments and constify variables] Signed-off-by: Mickaël Salaün --- tools/testing/selftests/landlock/fs_test.c | 47 ++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) (limited to 'tools') diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c index d5dab986f612..b6c4be3faf7a 100644 --- a/tools/testing/selftests/landlock/fs_test.c +++ b/tools/testing/selftests/landlock/fs_test.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include #include @@ -89,6 +90,40 @@ static const char dir_s3d3[] = TMP_DIR "/s3d1/s3d2/s3d3"; * └── s3d3 */ +static bool fgrep(FILE *const inf, const char *const str) +{ + char line[32]; + const int slen = strlen(str); + + while (!feof(inf)) { + if (!fgets(line, sizeof(line), inf)) + break; + if (strncmp(line, str, slen)) + continue; + + return true; + } + + return false; +} + +static bool supports_overlayfs(void) +{ + bool res; + FILE *const inf = fopen("/proc/filesystems", "r"); + + /* + * Consider that the filesystem is supported if we cannot get the + * supported ones. + */ + if (!inf) + return true; + + res = fgrep(inf, "nodev\toverlay\n"); + fclose(inf); + return res; +} + static void mkdir_parents(struct __test_metadata *const _metadata, const char *const path) { @@ -4001,6 +4036,9 @@ FIXTURE(layout2_overlay) {}; FIXTURE_SETUP(layout2_overlay) { + if (!supports_overlayfs()) + SKIP(return, "overlayfs is not supported"); + prepare_layout(_metadata); create_directory(_metadata, LOWER_BASE); @@ -4037,6 +4075,9 @@ FIXTURE_SETUP(layout2_overlay) FIXTURE_TEARDOWN(layout2_overlay) { + if (!supports_overlayfs()) + SKIP(return, "overlayfs is not supported"); + EXPECT_EQ(0, remove_path(lower_do1_fl3)); EXPECT_EQ(0, remove_path(lower_dl1_fl2)); EXPECT_EQ(0, remove_path(lower_fl1)); @@ -4068,6 +4109,9 @@ FIXTURE_TEARDOWN(layout2_overlay) TEST_F_FORK(layout2_overlay, no_restriction) { + if (!supports_overlayfs()) + SKIP(return, "overlayfs is not supported"); + ASSERT_EQ(0, test_open(lower_fl1, O_RDONLY)); ASSERT_EQ(0, test_open(lower_dl1, O_RDONLY)); ASSERT_EQ(0, test_open(lower_dl1_fl2, O_RDONLY)); @@ -4231,6 +4275,9 @@ TEST_F_FORK(layout2_overlay, same_content_different_file) size_t i; const char *path_entry; + if (!supports_overlayfs()) + SKIP(return, "overlayfs is not supported"); + /* Sets rules on base directories (i.e. outside overlay scope). */ ruleset_fd = create_ruleset(_metadata, ACCESS_RW, layer1_base); ASSERT_LE(0, ruleset_fd); -- cgit v1.2.3 From 8677e555f17f51321d0730b945aeb7d4b95f998f Mon Sep 17 00:00:00 2001 From: Jeff Xu Date: Sat, 14 Jan 2023 02:03:06 +0000 Subject: selftests/landlock: Test ptrace as much as possible with Yama MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Update ptrace tests according to all potential Yama security policies. This is required to make such tests pass even if Yama is enabled. Tests are not skipped but they now check both Landlock and Yama boundary restrictions at run time to keep a maximum test coverage (i.e. positive and negative testing). Signed-off-by: Jeff Xu Link: https://lore.kernel.org/r/20230114020306.1407195-2-jeffxu@google.com Cc: stable@vger.kernel.org [mic: Add curly braces around EXPECT_EQ() to make it build, and improve commit message] Co-developed-by: Mickaël Salaün Signed-off-by: Mickaël Salaün --- tools/testing/selftests/landlock/ptrace_test.c | 113 +++++++++++++++++++++---- 1 file changed, 96 insertions(+), 17 deletions(-) (limited to 'tools') diff --git a/tools/testing/selftests/landlock/ptrace_test.c b/tools/testing/selftests/landlock/ptrace_test.c index c28ef98ff3ac..55e7871631a1 100644 --- a/tools/testing/selftests/landlock/ptrace_test.c +++ b/tools/testing/selftests/landlock/ptrace_test.c @@ -19,6 +19,12 @@ #include "common.h" +/* Copied from security/yama/yama_lsm.c */ +#define YAMA_SCOPE_DISABLED 0 +#define YAMA_SCOPE_RELATIONAL 1 +#define YAMA_SCOPE_CAPABILITY 2 +#define YAMA_SCOPE_NO_ATTACH 3 + static void create_domain(struct __test_metadata *const _metadata) { int ruleset_fd; @@ -60,6 +66,25 @@ static int test_ptrace_read(const pid_t pid) return 0; } +static int get_yama_ptrace_scope(void) +{ + int ret; + char buf[2] = {}; + const int fd = open("/proc/sys/kernel/yama/ptrace_scope", O_RDONLY); + + if (fd < 0) + return 0; + + if (read(fd, buf, 1) < 0) { + close(fd); + return -1; + } + + ret = atoi(buf); + close(fd); + return ret; +} + /* clang-format off */ FIXTURE(hierarchy) {}; /* clang-format on */ @@ -232,8 +257,51 @@ 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_read_child, can_trace_child, can_read_parent, can_trace_parent; + + yama_ptrace_scope = get_yama_ptrace_scope(); + ASSERT_LE(0, yama_ptrace_scope); + + if (yama_ptrace_scope > YAMA_SCOPE_DISABLED) + TH_LOG("Incomplete tests due to Yama restrictions (scope %d)", + yama_ptrace_scope); + + /* + * can_read_child is true if a parent process can read its child + * process, which is only the case when the parent process is not + * isolated from the child with a dedicated Landlock domain. + */ + can_read_child = !variant->domain_parent; + + /* + * can_trace_child is true if a parent process can trace its child + * process. This depends on two conditions: + * - The parent process is not isolated from the child with a dedicated + * Landlock domain. + * - Yama allows tracing children (up to YAMA_SCOPE_RELATIONAL). + */ + can_trace_child = can_read_child && + yama_ptrace_scope <= YAMA_SCOPE_RELATIONAL; + + /* + * can_read_parent is true if a child process can read its parent + * process, which is only the case when the child process is not + * isolated from the parent with a dedicated Landlock domain. + */ + can_read_parent = !variant->domain_child; + + /* + * can_trace_parent is true if a child process can trace its parent + * process. This depends on two conditions: + * - The child process is not isolated from the parent with a dedicated + * Landlock domain. + * - Yama is disabled (YAMA_SCOPE_DISABLED). + */ + can_trace_parent = can_read_parent && + yama_ptrace_scope <= YAMA_SCOPE_DISABLED; /* * Removes all effective and permitted capabilities to not interfere @@ -264,16 +332,21 @@ TEST_F(hierarchy, trace) /* Waits for the parent to be in a domain, if any. */ ASSERT_EQ(1, read(pipe_parent[0], &buf_child, 1)); - /* Tests PTRACE_ATTACH and PTRACE_MODE_READ on the parent. */ + /* Tests PTRACE_MODE_READ on the parent. */ err_proc_read = test_ptrace_read(parent); + if (can_read_parent) { + EXPECT_EQ(0, err_proc_read); + } else { + EXPECT_EQ(EACCES, err_proc_read); + } + + /* Tests PTRACE_ATTACH on the parent. */ ret = ptrace(PTRACE_ATTACH, parent, NULL, 0); - if (variant->domain_child) { + if (can_trace_parent) { + EXPECT_EQ(0, ret); + } else { 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)); @@ -283,11 +356,11 @@ TEST_F(hierarchy, trace) /* Tests child PTRACE_TRACEME. */ ret = ptrace(PTRACE_TRACEME); - if (variant->domain_parent) { + if (can_trace_child) { + EXPECT_EQ(0, ret); + } else { EXPECT_EQ(-1, ret); EXPECT_EQ(EPERM, errno); - } else { - EXPECT_EQ(0, ret); } /* @@ -296,7 +369,7 @@ TEST_F(hierarchy, trace) */ ASSERT_EQ(1, write(pipe_child[1], ".", 1)); - if (!variant->domain_parent) { + if (can_trace_child) { ASSERT_EQ(0, raise(SIGSTOP)); } @@ -321,7 +394,7 @@ TEST_F(hierarchy, trace) ASSERT_EQ(1, read(pipe_child[0], &buf_parent, 1)); /* Tests child PTRACE_TRACEME. */ - if (!variant->domain_parent) { + if (can_trace_child) { ASSERT_EQ(child, waitpid(child, &status, 0)); ASSERT_EQ(1, WIFSTOPPED(status)); ASSERT_EQ(0, ptrace(PTRACE_DETACH, child, NULL, 0)); @@ -331,17 +404,23 @@ TEST_F(hierarchy, trace) EXPECT_EQ(ESRCH, errno); } - /* Tests PTRACE_ATTACH and PTRACE_MODE_READ on the child. */ + /* Tests PTRACE_MODE_READ on the child. */ err_proc_read = test_ptrace_read(child); + if (can_read_child) { + EXPECT_EQ(0, err_proc_read); + } else { + EXPECT_EQ(EACCES, err_proc_read); + } + + /* Tests PTRACE_ATTACH on the child. */ ret = ptrace(PTRACE_ATTACH, child, NULL, 0); - if (variant->domain_parent) { + if (can_trace_child) { + EXPECT_EQ(0, ret); + } else { 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)); -- cgit v1.2.3