Stop using the WCONTINUED flag with waitpid(2).

We don't use it for anything other than a debug message and it will
cause problems when intercept mode starts using ptrace(2).

include/sudo_compat.h

@@ -1,7 +1,7 @@
 /*
  * SPDX-License-Identifier: ISC
  *
- * Copyright (c) 1996, 1998-2005, 2008, 2009-2018
+ * Copyright (c) 1996, 1998-2005, 2008, 2009-2022
  *	Todd C. Miller <Todd.Miller@sudo.ws>
  *
  * Permission to use, copy, modify, and distribute this software for any
@@ -290,12 +290,6 @@ extern int errno;
 # define WCOREDUMP(x)	((x) & 0x80)
 #endif
 
-/* Older systems may not support WCONTINUED */
-#if !defined(WCONTINUED) && !defined(WIFCONTINUED)
-# define WCONTINUED		0
-# define WIFCONTINUED(x)	0
-#endif
-
 /* W_EXITCODE is not POSIX but the encoding of wait status is. */
 #ifndef W_EXITCODE
 # define W_EXITCODE(ret, sig)	((ret) << 8 | (sig))

src/exec_monitor.c

@@ -1,7 +1,7 @@
 /*
  * SPDX-License-Identifier: ISC
  *
- * Copyright (c) 2009-2021 Todd C. Miller <Todd.Miller@sudo.ws>
+ * Copyright (c) 2009-2022 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
@@ -197,23 +197,23 @@ mon_handle_sigchld(struct monitor_closure *mc)
 
     /* Read command status. */
     do {
-	pid = waitpid(mc->cmnd_pid, &status, WUNTRACED|WCONTINUED|WNOHANG);
+	pid = waitpid(mc->cmnd_pid, &status, WUNTRACED|WNOHANG);
     } while (pid == -1 && errno == EINTR);
     switch (pid) {
+    case -1:
+	if (errno != ECHILD) {
+	    sudo_warn(U_("%s: %s"), __func__, "waitpid");
+	    debug_return;
+	}
+	FALLTHROUGH;
     case 0:
 	/* Nothing to wait for. */
 	sudo_debug_printf(SUDO_DEBUG_INFO, "%s: no process to wait for",
 	    __func__);
 	debug_return;
-    case -1:
-	sudo_warn(U_("%s: %s"), __func__, "waitpid");
-	debug_return;
     }
 
-    if (WIFCONTINUED(status)) {
+    if (WIFSTOPPED(status)) {
-	sudo_debug_printf(SUDO_DEBUG_INFO, "%s: command (%d) resumed",
-	    __func__, (int)mc->cmnd_pid);
-    } else if (WIFSTOPPED(status)) {
 	if (sig2str(WSTOPSIG(status), signame) == -1)
 	    (void)snprintf(signame, sizeof(signame), "%d", WSTOPSIG(status));
 	sudo_debug_printf(SUDO_DEBUG_INFO, "%s: command (%d) stopped, SIG%s",
@@ -230,7 +230,7 @@ mon_handle_sigchld(struct monitor_closure *mc)
 	mc->cmnd_pid = -1;
     } else {
 	sudo_debug_printf(SUDO_DEBUG_WARN,
-	    "%s: unexpected wait status %d for command (%d)",
+	    "%s: unexpected wait status 0x%x for command (%d)",
 	    __func__, status, (int)mc->cmnd_pid);
     }
 
@@ -238,9 +238,7 @@ mon_handle_sigchld(struct monitor_closure *mc)
     if (mc->cstat->type == CMD_INVALID) {
 	/*
 	 * Store wait status in cstat and forward to parent if stopped.
-	 * Parent does not expect SIGCONT so don't bother sending it.
 	 */
-	if (!WIFCONTINUED(status)) {
 	mc->cstat->type = CMD_WSTATUS;
 	mc->cstat->val = status;
 	if (WIFSTOPPED(status)) {
@@ -250,7 +248,6 @@ mon_handle_sigchld(struct monitor_closure *mc)
 		mc->cmnd_pgrp = pid;
 	    send_status(mc->backchannel, mc->cstat);
 	}
-	}
     } else {
 	sudo_debug_printf(SUDO_DEBUG_WARN,
 	    "%s: not overwriting command status %d,%d with %d,%d",

src/exec_nopty.c

@@ -1,7 +1,7 @@
 /*
  * SPDX-License-Identifier: ISC
  *
- * Copyright (c) 2009-2020 Todd C. Miller <Todd.Miller@sudo.ws>
+ * Copyright (c) 2009-2022 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
@@ -493,23 +493,23 @@ handle_sigchld_nopty(struct exec_closure_nopty *ec)
 
     /* Read command status. */
     do {
-	pid = waitpid(ec->cmnd_pid, &status, WUNTRACED|WCONTINUED|WNOHANG);
+	pid = waitpid(ec->cmnd_pid, &status, WUNTRACED|WNOHANG);
     } while (pid == -1 && errno == EINTR);
     switch (pid) {
+    case -1:
+	if (errno != ECHILD) {
+	    sudo_warn(U_("%s: %s"), __func__, "waitpid");
+	    debug_return;
+	}
+	FALLTHROUGH;
     case 0:
 	/* Nothing to wait for. */
 	sudo_debug_printf(SUDO_DEBUG_INFO, "%s: no process to wait for",
 	    __func__);
 	debug_return;
-    case -1:
-	sudo_warn(U_("%s: %s"), __func__, "waitpid");
-	debug_return;
     }
 
-    if (WIFCONTINUED(status)) {
+    if (WIFSTOPPED(status)) {
-	sudo_debug_printf(SUDO_DEBUG_INFO, "%s: command (%d) resumed",
-	    __func__, (int)ec->cmnd_pid);
-    } else if (WIFSTOPPED(status)) {
 	/*
 	 * Save the controlling terminal's process group so we can restore it
 	 * after we resume, if needed.  Most well-behaved shells change the
@@ -594,10 +594,15 @@ handle_sigchld_nopty(struct exec_closure_nopty *ec)
 		(void)snprintf(signame, sizeof(signame), "%d", WTERMSIG(status));
 	    sudo_debug_printf(SUDO_DEBUG_INFO, "%s: command (%d) killed, SIG%s",
 		__func__, (int)ec->cmnd_pid, signame);
-	} else {
+	} else if (WIFEXITED(status)) {
 	    sudo_debug_printf(SUDO_DEBUG_INFO, "%s: command (%d) exited: %d",
 		__func__, (int)ec->cmnd_pid, WEXITSTATUS(status));
+	} else {
+	    sudo_debug_printf(SUDO_DEBUG_WARN,
+		"%s: unexpected wait status 0x%x for command (%d)",
+		__func__, status, (int)ec->cmnd_pid);
 	}
+
 	/* Don't overwrite execve() failure with command exit status. */
 	if (ec->cstat->type == CMD_INVALID) {
 	    ec->cstat->type = CMD_WSTATUS;

src/exec_pty.c

@@ -1,7 +1,7 @@
 /*
  * SPDX-License-Identifier: ISC
  *
- * Copyright (c) 2009-2021 Todd C. Miller <Todd.Miller@sudo.ws>
+ * Copyright (c) 2009-2022 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
@@ -1049,17 +1049,20 @@ handle_sigchld_pty(struct exec_closure_pty *ec)
      * Monitor process was signaled; wait for it as needed.
      */
     do {
-	pid = waitpid(ec->monitor_pid, &status, WUNTRACED|WCONTINUED|WNOHANG);
+	pid = waitpid(ec->monitor_pid, &status, WUNTRACED|WNOHANG);
     } while (pid == -1 && errno == EINTR);
     switch (pid) {
+    case -1:
+	if (errno != ECHILD) {
+	    sudo_warn(U_("%s: %s"), __func__, "waitpid");
+	    debug_return;
+	}
+	FALLTHROUGH;
     case 0:
 	/* Nothing to wait for. */
 	sudo_debug_printf(SUDO_DEBUG_INFO, "%s: no process to wait for",
 	    __func__);
 	debug_return;
-    case -1:
-	sudo_warn(U_("%s: %s"), __func__, "waitpid");
-	debug_return;
     }
 
     /*
@@ -1067,10 +1070,7 @@ handle_sigchld_pty(struct exec_closure_pty *ec)
      * If it was stopped, we should stop too (the command keeps
      * running in its pty) and continue it when we come back.
      */
-    if (WIFCONTINUED(status)) {
+    if (WIFSTOPPED(status)) {
-	sudo_debug_printf(SUDO_DEBUG_INFO, "%s: monitor (%d) resumed",
-	    __func__, (int)ec->monitor_pid);
-    } else if (WIFSTOPPED(status)) {
 	sudo_debug_printf(SUDO_DEBUG_INFO,
 	    "monitor stopped, suspending sudo");
 	n = suspend_sudo(ec, WSTOPSIG(status));
@@ -1085,10 +1085,14 @@ handle_sigchld_pty(struct exec_closure_pty *ec)
 	sudo_debug_printf(SUDO_DEBUG_INFO, "%s: monitor (%d) killed, SIG%s",
 	    __func__, (int)ec->monitor_pid, signame);
 	ec->monitor_pid = -1;
-    } else {
+    } else if (WIFEXITED(status)) {
 	sudo_debug_printf(SUDO_DEBUG_INFO,
 	    "%s: monitor exited, status %d", __func__, WEXITSTATUS(status));
 	ec->monitor_pid = -1;
+    } else {
+	sudo_debug_printf(SUDO_DEBUG_WARN,
+	    "%s: unexpected wait status 0x%x for monitor (%d)",
+	    __func__, status, (int)ec->monitor_pid);
     }
     debug_return;
 }