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-rw-r--r--src/test/test-capability.c245
1 files changed, 245 insertions, 0 deletions
diff --git a/src/test/test-capability.c b/src/test/test-capability.c
new file mode 100644
index 0000000..325d7c8
--- /dev/null
+++ b/src/test/test-capability.c
@@ -0,0 +1,245 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <netinet/in.h>
+#include <pwd.h>
+#include <sys/capability.h>
+#include <sys/prctl.h>
+#include <sys/socket.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include "alloc-util.h"
+#include "capability-util.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "macro.h"
+#include "missing_prctl.h"
+#include "parse-util.h"
+#include "tests.h"
+#include "util.h"
+
+static uid_t test_uid = -1;
+static gid_t test_gid = -1;
+
+#if HAS_FEATURE_ADDRESS_SANITIZER
+/* Keep CAP_SYS_PTRACE when running under Address Sanitizer */
+static const uint64_t test_flags = UINT64_C(1) << CAP_SYS_PTRACE;
+#else
+/* We keep CAP_DAC_OVERRIDE to avoid errors with gcov when doing test coverage */
+static const uint64_t test_flags = UINT64_C(1) << CAP_DAC_OVERRIDE;
+#endif
+
+/* verify cap_last_cap() against /proc/sys/kernel/cap_last_cap */
+static void test_last_cap_file(void) {
+ _cleanup_free_ char *content = NULL;
+ unsigned long val = 0;
+ int r;
+
+ r = read_one_line_file("/proc/sys/kernel/cap_last_cap", &content);
+ assert_se(r >= 0);
+
+ r = safe_atolu(content, &val);
+ assert_se(r >= 0);
+ assert_se(val != 0);
+ assert_se(val == cap_last_cap());
+}
+
+/* verify cap_last_cap() against syscall probing */
+static void test_last_cap_probe(void) {
+ unsigned long p = (unsigned long)CAP_LAST_CAP;
+
+ if (prctl(PR_CAPBSET_READ, p) < 0) {
+ for (p--; p > 0; p --)
+ if (prctl(PR_CAPBSET_READ, p) >= 0)
+ break;
+ } else {
+ for (;; p++)
+ if (prctl(PR_CAPBSET_READ, p+1) < 0)
+ break;
+ }
+
+ assert_se(p != 0);
+ assert_se(p == cap_last_cap());
+}
+
+static void fork_test(void (*test_func)(void)) {
+ pid_t pid = 0;
+
+ pid = fork();
+ assert_se(pid >= 0);
+ if (pid == 0) {
+ test_func();
+ exit(EXIT_SUCCESS);
+ } else if (pid > 0) {
+ int status;
+
+ assert_se(waitpid(pid, &status, 0) > 0);
+ assert_se(WIFEXITED(status) && WEXITSTATUS(status) == 0);
+ }
+}
+
+static void show_capabilities(void) {
+ cap_t caps;
+ char *text;
+
+ caps = cap_get_proc();
+ assert_se(caps);
+
+ text = cap_to_text(caps, NULL);
+ assert_se(text);
+
+ log_info("Capabilities:%s", text);
+ cap_free(caps);
+ cap_free(text);
+}
+
+static int setup_tests(bool *run_ambient) {
+ struct passwd *nobody;
+ int r;
+
+ nobody = getpwnam(NOBODY_USER_NAME);
+ if (!nobody)
+ return log_error_errno(errno, "Could not find nobody user: %m");
+
+ test_uid = nobody->pw_uid;
+ test_gid = nobody->pw_gid;
+
+ *run_ambient = false;
+
+ r = prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_CLEAR_ALL, 0, 0, 0);
+
+ /* There's support for PR_CAP_AMBIENT if the prctl() call
+ * succeeded or error code was something else than EINVAL. The
+ * EINVAL check should be good enough to rule out false
+ * positives. */
+
+ if (r >= 0 || errno != EINVAL)
+ *run_ambient = true;
+
+ return 0;
+}
+
+static void test_drop_privileges_keep_net_raw(void) {
+ int sock;
+
+ sock = socket(AF_INET, SOCK_RAW, IPPROTO_UDP);
+ assert_se(sock >= 0);
+ safe_close(sock);
+
+ assert_se(drop_privileges(test_uid, test_gid, test_flags | (1ULL << CAP_NET_RAW)) >= 0);
+ assert_se(getuid() == test_uid);
+ assert_se(getgid() == test_gid);
+ show_capabilities();
+
+ sock = socket(AF_INET, SOCK_RAW, IPPROTO_UDP);
+ assert_se(sock >= 0);
+ safe_close(sock);
+}
+
+static void test_drop_privileges_dontkeep_net_raw(void) {
+ int sock;
+
+ sock = socket(AF_INET, SOCK_RAW, IPPROTO_UDP);
+ assert_se(sock >= 0);
+ safe_close(sock);
+
+ assert_se(drop_privileges(test_uid, test_gid, test_flags) >= 0);
+ assert_se(getuid() == test_uid);
+ assert_se(getgid() == test_gid);
+ show_capabilities();
+
+ sock = socket(AF_INET, SOCK_RAW, IPPROTO_UDP);
+ assert_se(sock < 0);
+}
+
+static void test_drop_privileges_fail(void) {
+ assert_se(drop_privileges(test_uid, test_gid, test_flags) >= 0);
+ assert_se(getuid() == test_uid);
+ assert_se(getgid() == test_gid);
+
+ assert_se(drop_privileges(test_uid, test_gid, test_flags) < 0);
+ assert_se(drop_privileges(0, 0, test_flags) < 0);
+}
+
+static void test_drop_privileges(void) {
+ fork_test(test_drop_privileges_keep_net_raw);
+ fork_test(test_drop_privileges_dontkeep_net_raw);
+ fork_test(test_drop_privileges_fail);
+}
+
+static void test_have_effective_cap(void) {
+ assert_se(have_effective_cap(CAP_KILL));
+ assert_se(have_effective_cap(CAP_CHOWN));
+
+ assert_se(drop_privileges(test_uid, test_gid, test_flags | (1ULL << CAP_KILL)) >= 0);
+ assert_se(getuid() == test_uid);
+ assert_se(getgid() == test_gid);
+
+ assert_se(have_effective_cap(CAP_KILL));
+ assert_se(!have_effective_cap(CAP_CHOWN));
+}
+
+static void test_update_inherited_set(void) {
+ cap_t caps;
+ uint64_t set = 0;
+ cap_flag_value_t fv;
+
+ caps = cap_get_proc();
+ assert_se(caps);
+
+ set = (UINT64_C(1) << CAP_CHOWN);
+
+ assert_se(!capability_update_inherited_set(caps, set));
+ assert_se(!cap_get_flag(caps, CAP_CHOWN, CAP_INHERITABLE, &fv));
+ assert(fv == CAP_SET);
+
+ cap_free(caps);
+}
+
+static void test_set_ambient_caps(void) {
+ cap_t caps;
+ uint64_t set = 0;
+ cap_flag_value_t fv;
+
+ assert_se(prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_CHOWN, 0, 0) == 0);
+
+ set = (UINT64_C(1) << CAP_CHOWN);
+
+ assert_se(!capability_ambient_set_apply(set, true));
+
+ caps = cap_get_proc();
+ assert_se(!cap_get_flag(caps, CAP_CHOWN, CAP_INHERITABLE, &fv));
+ assert(fv == CAP_SET);
+ cap_free(caps);
+
+ assert_se(prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_CHOWN, 0, 0) == 1);
+}
+
+int main(int argc, char *argv[]) {
+ bool run_ambient;
+
+ test_setup_logging(LOG_INFO);
+
+ test_last_cap_file();
+ test_last_cap_probe();
+
+ log_info("have ambient caps: %s", yes_no(ambient_capabilities_supported()));
+
+ if (getuid() != 0)
+ return log_tests_skipped("not running as root");
+
+ if (setup_tests(&run_ambient) < 0)
+ return log_tests_skipped("setup failed");
+
+ show_capabilities();
+
+ test_drop_privileges();
+ test_update_inherited_set();
+
+ fork_test(test_have_effective_cap);
+
+ if (run_ambient)
+ fork_test(test_set_ambient_caps);
+
+ return 0;
+}