Provide proccontrol(1), an utility to control processes behaviour, related

to procctl(2).

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week

usr.bin/Makefile

@@ -122,6 +122,7 @@ SUBDIR=	alias \
 	pr \
 	printenv \
 	printf \
+	proccontrol \
 	procstat \
 	protect \
 	rctl \

usr.bin/proccontrol/Makefile

@@ -0,0 +1,7 @@
+# $FreeBSD$
+
+PROG=   proccontrol
+WARNS?=	6
+MK_MAN=no
+
+.include <bsd.prog.mk>

usr.bin/proccontrol/proccontrol.c

@@ -0,0 +1,180 @@
+/*-
+ * Copyright (c) 2016 The FreeBSD Foundation
+ * All rights reserved.
+ *
+ * This software was developed by Konstantin Belousov <kib@FreeBSD.org>
+ * under sponsorship from the FreeBSD Foundation.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/procctl.h>
+#include <err.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+enum {
+	MODE_INVALID,
+	MODE_TRACE,
+	MODE_TRAPCAP,
+};
+
+static pid_t
+str2pid(const char *str)
+{
+	pid_t res;
+	char *tail;
+
+	res = strtol(str, &tail, 0);
+	if (*tail != '\0') {
+		warnx("non-numeric pid");
+		return (-1);
+	}
+	return (res);
+}
+
+static void __dead2
+usage(void)
+{
+
+	fprintf(stderr, "Usage: proccontrol -m (trace|trapcap) [-q] "
+	    "[-s (enable|disable)] [-p pid | command]\n");
+	exit(1);
+}
+
+int
+main(int argc, char *argv[])
+{
+	int arg, ch, error, mode;
+	pid_t pid;
+	bool enable, do_command, query;
+
+	mode = MODE_INVALID;
+	enable = true;
+	pid = -1;
+	query = false;
+	while ((ch = getopt(argc, argv, "m:qs:p:")) != -1) {
+		switch (ch) {
+		case 'm':
+			if (strcmp(optarg, "trace") == 0)
+				mode = MODE_TRACE;
+			else if (strcmp(optarg, "trapcap") == 0)
+				mode = MODE_TRAPCAP;
+			else
+				usage();
+			break;
+		case 's':
+			if (strcmp(optarg, "enable") == 0)
+				enable = true;
+			else if (strcmp(optarg, "disable") == 0)
+				enable = false;
+			else
+				usage();
+			break;
+		case 'p':
+			pid = str2pid(optarg);
+			break;
+		case 'q':
+			query = true;
+			break;
+		case '?':
+		default:
+			usage();
+			break;
+		}
+	}
+	argc -= optind;
+	argv += optind;
+	do_command = argc != 0;
+	if (do_command) {
+		if (pid != -1 || query)
+			usage();
+		pid = getpid();
+	} else if (pid == -1) {
+		pid = getpid();
+	}
+
+	if (query) {
+		switch (mode) {
+		case MODE_TRACE:
+			error = procctl(P_PID, pid, PROC_TRACE_STATUS, &arg);
+			break;
+		case MODE_TRAPCAP:
+			error = procctl(P_PID, pid, PROC_TRAPCAP_STATUS, &arg);
+			break;
+		default:
+			usage();
+			break;
+		}
+		if (error != 0)
+			err(1, "procctl status");
+		switch (mode) {
+		case MODE_TRACE:
+			if (arg == -1)
+				printf("disabled\n");
+			else if (arg == 0)
+				printf("enabled, no debugger\n");
+			else
+				printf("enabled, traced by %d\n", arg);
+			break;
+		case MODE_TRAPCAP:
+			switch (arg) {
+			case PROC_TRAPCAP_CTL_ENABLE:
+				printf("enabled\n");
+				break;
+			case PROC_TRAPCAP_CTL_DISABLE:
+				printf("disabled\n");
+				break;
+			}
+			break;
+		}
+	} else {
+		switch (mode) {
+		case MODE_TRACE:
+			arg = enable ? PROC_TRACE_CTL_ENABLE :
+			    PROC_TRACE_CTL_DISABLE;
+			error = procctl(P_PID, pid, PROC_TRACE_CTL, &arg);
+			break;
+		case MODE_TRAPCAP:
+			arg = enable ? PROC_TRAPCAP_CTL_ENABLE :
+			    PROC_TRAPCAP_CTL_DISABLE;
+			error = procctl(P_PID, pid, PROC_TRAPCAP_CTL, &arg);
+			break;
+		default:
+			usage();
+			break;
+		}
+		if (error != 0)
+			err(1, "procctl ctl");
+		if (do_command) {
+			error = execvp(argv[0], argv);
+			err(1, "exec");
+		}
+	}
+	exit(0);
+}