diff options
Diffstat (limited to 'tools/testing/selftests/landlock/ptrace_test.c')
| -rw-r--r-- | tools/testing/selftests/landlock/ptrace_test.c | 258 |
1 files changed, 238 insertions, 20 deletions
diff --git a/tools/testing/selftests/landlock/ptrace_test.c b/tools/testing/selftests/landlock/ptrace_test.c index c28ef98ff3ac..4e356334ecb7 100644 --- a/tools/testing/selftests/landlock/ptrace_test.c +++ b/tools/testing/selftests/landlock/ptrace_test.c @@ -4,6 +4,7 @@ * * Copyright © 2017-2020 Mickaël Salaün <mic@digikod.net> * Copyright © 2019-2020 ANSSI + * Copyright © 2024-2025 Microsoft Corporation */ #define _GNU_SOURCE @@ -17,8 +18,13 @@ #include <sys/wait.h> #include <unistd.h> +#include "audit.h" #include "common.h" +/* Copied from security/yama/yama_lsm.c */ +#define YAMA_SCOPE_DISABLED 0 +#define YAMA_SCOPE_RELATIONAL 1 + 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 @@ -246,7 +314,7 @@ TEST_F(hierarchy, trace) ASSERT_EQ(0, pipe2(pipe_parent, O_CLOEXEC)); if (variant->domain_both) { create_domain(_metadata); - if (!_metadata->passed) + if (!__test_passed(_metadata)) /* Aborts before forking. */ return; } @@ -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); } /* @@ -296,13 +369,13 @@ 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)); } /* Waits for the parent PTRACE_ATTACH test. */ ASSERT_EQ(1, read(pipe_parent[0], &buf_child, 1)); - _exit(_metadata->passed ? EXIT_SUCCESS : EXIT_FAILURE); + _exit(_metadata->exit_code); return; } @@ -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)); @@ -351,9 +430,148 @@ TEST_F(hierarchy, trace) /* Signals that the parent PTRACE_ATTACH test is done. */ ASSERT_EQ(1, write(pipe_parent[1], ".", 1)); ASSERT_EQ(child, waitpid(child, &status, 0)); + if (WIFSIGNALED(status) || !WIFEXITED(status) || WEXITSTATUS(status) != EXIT_SUCCESS) - _metadata->passed = 0; + _metadata->exit_code = KSFT_FAIL; +} + +static int matches_log_ptrace(struct __test_metadata *const _metadata, + int audit_fd, const pid_t opid) +{ + static const char log_template[] = REGEX_LANDLOCK_PREFIX + " blockers=ptrace opid=%d ocomm=\"ptrace_test\"$"; + char log_match[sizeof(log_template) + 10]; + int log_match_len; + + log_match_len = + snprintf(log_match, sizeof(log_match), log_template, opid); + if (log_match_len > sizeof(log_match)) + return -E2BIG; + + return audit_match_record(audit_fd, AUDIT_LANDLOCK_ACCESS, log_match, + NULL); +} + +FIXTURE(audit) +{ + struct audit_filter audit_filter; + int audit_fd; +}; + +FIXTURE_SETUP(audit) +{ + disable_caps(_metadata); + set_cap(_metadata, CAP_AUDIT_CONTROL); + self->audit_fd = audit_init_with_exe_filter(&self->audit_filter); + EXPECT_LE(0, self->audit_fd); + clear_cap(_metadata, CAP_AUDIT_CONTROL); +} + +FIXTURE_TEARDOWN_PARENT(audit) +{ + EXPECT_EQ(0, audit_cleanup(-1, NULL)); +} + +/* Test PTRACE_TRACEME and PTRACE_ATTACH for parent and child. */ +TEST_F(audit, trace) +{ + pid_t child; + int status; + int pipe_child[2], pipe_parent[2]; + int yama_ptrace_scope; + char buf_parent; + struct audit_records records; + + /* Makes sure there is no superfluous logged records. */ + EXPECT_EQ(0, audit_count_records(self->audit_fd, &records)); + EXPECT_EQ(0, records.access); + EXPECT_EQ(0, records.domain); + + 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); + + /* + * Removes all effective and permitted capabilities to not interfere + * with cap_ptrace_access_check() in case of PTRACE_MODE_FSCREDS. + */ + drop_caps(_metadata); + + ASSERT_EQ(0, pipe2(pipe_child, O_CLOEXEC)); + ASSERT_EQ(0, pipe2(pipe_parent, O_CLOEXEC)); + + child = fork(); + ASSERT_LE(0, child); + if (child == 0) { + char buf_child; + + ASSERT_EQ(0, close(pipe_parent[1])); + ASSERT_EQ(0, close(pipe_child[0])); + + /* Waits for the parent to be in a domain, if any. */ + ASSERT_EQ(1, read(pipe_parent[0], &buf_child, 1)); + + /* Tests child PTRACE_TRACEME. */ + EXPECT_EQ(-1, ptrace(PTRACE_TRACEME)); + EXPECT_EQ(EPERM, errno); + /* We should see the child process. */ + EXPECT_EQ(0, matches_log_ptrace(_metadata, self->audit_fd, + getpid())); + + EXPECT_EQ(0, audit_count_records(self->audit_fd, &records)); + EXPECT_EQ(0, records.access); + /* Checks for a domain creation. */ + EXPECT_EQ(1, records.domain); + + /* + * Signals that the PTRACE_ATTACH test is done and the + * PTRACE_TRACEME test is ongoing. + */ + ASSERT_EQ(1, write(pipe_child[1], ".", 1)); + + /* Waits for the parent PTRACE_ATTACH test. */ + ASSERT_EQ(1, read(pipe_parent[0], &buf_child, 1)); + _exit(_metadata->exit_code); + return; + } + + ASSERT_EQ(0, close(pipe_child[1])); + ASSERT_EQ(0, close(pipe_parent[0])); + create_domain(_metadata); + + /* Signals that the parent is in a domain. */ + ASSERT_EQ(1, write(pipe_parent[1], ".", 1)); + + /* + * 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)); + + /* 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 on the child. */ + EXPECT_EQ(-1, ptrace(PTRACE_ATTACH, child, NULL, 0)); + EXPECT_EQ(EPERM, errno); + EXPECT_EQ(0, matches_log_ptrace(_metadata, self->audit_fd, child)); + + /* Signals that the parent PTRACE_ATTACH test is done. */ + ASSERT_EQ(1, write(pipe_parent[1], ".", 1)); + ASSERT_EQ(child, waitpid(child, &status, 0)); + if (WIFSIGNALED(status) || !WIFEXITED(status) || + WEXITSTATUS(status) != EXIT_SUCCESS) + _metadata->exit_code = KSFT_FAIL; + + /* Makes sure there is no superfluous logged records. */ + EXPECT_EQ(0, audit_count_records(self->audit_fd, &records)); + EXPECT_EQ(0, records.access); + EXPECT_EQ(0, records.domain); } TEST_HARNESS_MAIN |