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-rw-r--r--src/regress/intercept/test_ptrace.c242
1 files changed, 242 insertions, 0 deletions
diff --git a/src/regress/intercept/test_ptrace.c b/src/regress/intercept/test_ptrace.c
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index 0000000..72d4b2c
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+++ b/src/regress/intercept/test_ptrace.c
@@ -0,0 +1,242 @@
+/*
+ * Copyright (c) 2022 Todd C. Miller <Todd.Miller@sudo.ws>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * This is an open source non-commercial project. Dear PVS-Studio, please check it.
+ * PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
+ */
+
+/*
+ * Test program to exercise seccomp(2) and ptrace(2) intercept code.
+ *
+ * Usage: test_ptrace [-d 1-3] [command]
+ */
+
+/* Ignore architecture restrictions and define this unilaterally. */
+#define HAVE_PTRACE_INTERCEPT
+#include "exec_ptrace.c"
+
+static sig_atomic_t got_sigchld;
+static int debug;
+int sudo_debug_instance = SUDO_DEBUG_INSTANCE_INITIALIZER;
+
+sudo_dso_public int main(int argc, char *argv[]);
+
+static void
+handler(int signo)
+{
+ if (signo == SIGCHLD)
+ got_sigchld = 1;
+}
+
+void
+intercept_closure_reset(struct intercept_closure *closure)
+{
+ memset(closure, 0, sizeof(*closure));
+}
+
+bool
+intercept_check_policy(const char *command, int argc, char **argv, int envc,
+ char **envp, const char *runcwd, int *oldcwd, void *v)
+{
+ struct intercept_closure *closure = v;
+ struct stat sb1, sb2;
+ bool is_denied;
+ debug_decl(intercept_check_policy, SUDO_DEBUG_EXEC);
+
+ /* Fake policy decisions. */
+ is_denied = stat(command, &sb1) == 0 && stat("/usr/bin/who", &sb2) == 0 &&
+ sb1.st_ino == sb2.st_ino && sb1.st_dev == sb2.st_dev;
+ if (is_denied) {
+ sudo_debug_printf(SUDO_DEBUG_DIAG, "denied %s", command);
+ closure->state = POLICY_REJECT;
+ } else {
+ sudo_debug_printf(SUDO_DEBUG_DIAG, "allowed %s", command);
+ closure->state = POLICY_TEST;
+ }
+ *oldcwd = -1;
+
+ debug_return_bool(true);
+}
+
+static void
+init_debug_files(struct sudo_conf_debug_file_list *file_list,
+ struct sudo_debug_file *file)
+{
+ debug_decl(init_debug_files, SUDO_DEBUG_EXEC);
+
+ TAILQ_INIT(file_list);
+ switch (debug) {
+ case 0:
+ debug_return;
+ case 1:
+ file->debug_flags = (char *)"exec@diag";
+ break;
+ case 2:
+ file->debug_flags = (char *)"exec@info";
+ break;
+ default:
+ file->debug_flags = (char *)"exec@debug";
+ break;
+ }
+ file->debug_file = (char *)"/dev/stderr";
+ TAILQ_INSERT_HEAD(file_list, file, entries);
+
+ debug_return;
+}
+
+int
+sudo_sigaction(int signo, struct sigaction *sa, struct sigaction *osa)
+{
+ return sigaction(signo, sa, osa);
+}
+
+/* STUB */
+void
+log_suspend(struct exec_closure *ec, int signo)
+{
+ return;
+}
+
+int
+main(int argc, char *argv[])
+{
+ struct sudo_conf_debug_file_list debug_files;
+ struct sudo_debug_file debug_file;
+ const char *base, *shell = _PATH_SUDO_BSHELL;
+ struct intercept_closure closure = { 0 };
+ const char *errstr;
+ sigset_t blocked, empty;
+ struct sigaction sa;
+ pid_t child, my_pid, pid, my_pgrp;
+ int ch, status;
+ debug_decl_vars(main, SUDO_DEBUG_MAIN);
+
+ initprogname(argc > 0 ? argv[0] : "test_ptrace");
+
+ if (!have_seccomp_action("trap"))
+ sudo_fatalx("SECCOMP_MODE_FILTER not available in this kernel");
+
+ while ((ch = getopt(argc, argv, "d:")) != -1) {
+ switch (ch) {
+ case 'd':
+ debug = sudo_strtonum(optarg, 1, INT_MAX, &errstr);
+ if (errstr != NULL)
+ sudo_fatalx(U_("%s: %s"), optarg, U_(errstr));
+ break;
+ default:
+ fprintf(stderr, "usage: %s [-d 1-3] [command]\n", getprogname());
+ return EXIT_FAILURE;
+ }
+ }
+ argc -= optind;
+ argv += optind;
+
+ if (argc > 0)
+ shell = argv[0];
+ base = strrchr(shell, '/');
+ base = base ? base + 1 : shell;
+
+ /* Set debug level based on the debug flag. */
+ init_debug_files(&debug_files, &debug_file);
+ sudo_debug_instance = sudo_debug_register(getprogname(),
+ NULL, NULL, &debug_files, -1);
+ if (sudo_debug_instance == SUDO_DEBUG_INSTANCE_ERROR)
+ return EXIT_FAILURE;
+
+ /* Block SIGCHLD and SIGUSR during critical section. */
+ sigemptyset(&empty);
+ sigemptyset(&blocked);
+ sigaddset(&blocked, SIGCHLD);
+ sigaddset(&blocked, SIGUSR1);
+ sigprocmask(SIG_BLOCK, &blocked, NULL);
+
+ /* Signal handler sets a flag for SIGCHLD, nothing for SIGUSR1. */
+ memset(&sa, 0, sizeof(sa));
+ sigemptyset(&sa.sa_mask);
+ sa.sa_flags = SA_RESTART;
+ sa.sa_handler = handler;
+ sigaction(SIGCHLD, &sa, NULL);
+ sigaction(SIGUSR1, &sa, NULL);
+
+ /* Fork a shell. */
+ my_pid = getpid();
+ my_pgrp = getpgrp();
+ child = fork();
+ switch (child) {
+ case -1:
+ sudo_fatal("fork");
+ case 0:
+ /* child */
+ if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) == -1)
+ sudo_fatal("%s", "unable to set no_new_privs bit");
+ if (!set_exec_filter())
+ _exit(EXIT_FAILURE);
+
+ /* Suspend child until tracer seizes control and sends SIGUSR1. */
+ sigsuspend(&empty);
+ execl(shell, base, NULL);
+ sudo_fatal("execl");
+ default:
+ /* Parent attaches to child and allows it to continue. */
+ if (exec_ptrace_seize(child) == -1)
+ return EXIT_FAILURE;
+ break;
+ }
+
+ /* Wait for SIGCHLD. */
+ for (;;) {
+ sigsuspend(&empty);
+ if (!got_sigchld)
+ continue;
+ got_sigchld = 0;
+
+ for (;;) {
+ do {
+ pid = waitpid(-1, &status, __WALL|WNOHANG);
+ } while (pid == -1 && errno == EINTR);
+ if (pid <= 0) {
+ if (pid == -1 && errno != ECHILD)
+ sudo_fatal("waitpid");
+ /* No child to wait for. */
+ break;
+ }
+
+ if (WIFEXITED(status)) {
+ sudo_debug_printf(SUDO_DEBUG_DIAG, "%d: exited %d",
+ pid, WEXITSTATUS(status));
+ if (pid == child)
+ return WEXITSTATUS(status);
+ } else if (WIFSIGNALED(status)) {
+ sudo_debug_printf(SUDO_DEBUG_DIAG, "%d: killed by signal %d",
+ pid, WTERMSIG(status));
+ if (pid == child)
+ return WTERMSIG(status) | 128;
+ } else if (WIFSTOPPED(status)) {
+ if (exec_ptrace_stopped(pid, status, &closure)) {
+ if (pid == child) {
+ suspend_sudo_nopty(NULL, WSTOPSIG(status), my_pid,
+ my_pgrp, child);
+ if (kill(child, SIGCONT) != 0)
+ sudo_warn("kill(%d, SIGCONT)", (int)child);
+ }
+ }
+ } else {
+ sudo_fatalx("%d: unknown status 0x%x", pid, status);
+ }
+ }
+ }
+}