1/*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2008 Robert N. M. Watson
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include <sys/types.h>
30#include <sys/sysctl.h>
31
32#include <err.h>
33#include <errno.h>
34#include <fcntl.h>
35#include <kvm.h>
36#include <limits.h>
37#include <stdio.h>
38#include <stdlib.h>
39#include <string.h>
40#include <sysexits.h>
41#include <unistd.h>
42
43#include "ddb.h"
44
45/*
46 * Interface with the ddb(4) capture buffer of a live kernel using sysctl, or
47 * for a crash dump using libkvm.
48 */
49#define	SYSCTL_DDB_CAPTURE_BUFOFF	"debug.ddb.capture.bufoff"
50#define	SYSCTL_DDB_CAPTURE_BUFSIZE	"debug.ddb.capture.bufsize"
51#define	SYSCTL_DDB_CAPTURE_MAXBUFSIZE	"debug.ddb.capture.maxbufsize"
52#define	SYSCTL_DDB_CAPTURE_DATA		"debug.ddb.capture.data"
53#define	SYSCTL_DDB_CAPTURE_INPROGRESS	"debug.ddb.capture.inprogress"
54
55static struct nlist namelist[] = {
56#define X_DB_CAPTURE_BUF	0
57	{ .n_name = "_db_capture_buf" },
58#define X_DB_CAPTURE_BUFSIZE	1
59	{ .n_name = "_db_capture_bufsize" },
60#define X_DB_CAPTURE_MAXBUFSIZE	2
61	{ .n_name = "_db_capture_maxbufsize" },
62#define X_DB_CAPTURE_BUFOFF	3
63	{ .n_name = "_db_capture_bufoff" },
64#define	X_DB_CAPTURE_INPROGRESS	4
65	{ .n_name = "_db_capture_inprogress" },
66	{ .n_name = "" },
67};
68
69static int
70kread(kvm_t *kvm, void *kvm_pointer, void *address, size_t size,
71    size_t offset)
72{
73	ssize_t ret;
74
75	ret = kvm_read(kvm, (unsigned long)kvm_pointer + offset, address,
76	    size);
77	if (ret < 0 || (size_t)ret != size)
78		return (-1);
79	return (0);
80}
81
82static int
83kread_symbol(kvm_t *kvm, int read_index, void *address, size_t size,
84    size_t offset)
85{
86	ssize_t ret;
87
88	ret = kvm_read(kvm, namelist[read_index].n_value + offset, address, size);
89	if (ret < 0 || (size_t)ret != size)
90		return (-1);
91	return (0);
92}
93
94static void
95ddb_capture_print_kvm(kvm_t *kvm)
96{
97	u_int db_capture_bufoff;
98	char *buffer, *db_capture_buf;
99
100	if (kread_symbol(kvm, X_DB_CAPTURE_BUF, &db_capture_buf,
101	    sizeof(db_capture_buf), 0) < 0)
102		errx(-1, "kvm: unable to read db_capture_buf");
103
104	if (kread_symbol(kvm, X_DB_CAPTURE_BUFOFF, &db_capture_bufoff,
105	    sizeof(db_capture_bufoff), 0) < 0)
106		errx(-1, "kvm: unable to read db_capture_bufoff");
107
108	buffer = malloc(db_capture_bufoff + 1);
109	if (buffer == NULL)
110		err(-1, "malloc: db_capture_bufoff (%u)",
111		    db_capture_bufoff);
112	bzero(buffer, db_capture_bufoff + 1);
113
114	if (kread(kvm, db_capture_buf, buffer, db_capture_bufoff, 0) < 0)
115		errx(-1, "kvm: unable to read buffer");
116
117	printf("%s\n", buffer);
118	free(buffer);
119}
120
121static void
122ddb_capture_print_sysctl(void)
123{
124	size_t buflen, len;
125	char *buffer;
126	int ret;
127
128repeat:
129	if (sysctlbyname(SYSCTL_DDB_CAPTURE_DATA, NULL, &buflen, NULL, 0) < 0)
130		err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_DATA);
131	if (buflen == 0)
132		return;
133	buffer = malloc(buflen);
134	if (buffer == NULL)
135		err(EX_OSERR, "malloc");
136	bzero(buffer, buflen);
137	len = buflen;
138	ret = sysctlbyname(SYSCTL_DDB_CAPTURE_DATA, buffer, &len, NULL, 0);
139	if (ret < 0 && errno != ENOMEM)
140		err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_DATA);
141	if (ret < 0) {
142		free(buffer);
143		goto repeat;
144	}
145
146	printf("%s\n", buffer);
147	free(buffer);
148}
149
150static void
151ddb_capture_status_kvm(kvm_t *kvm)
152{
153	u_int db_capture_bufoff, db_capture_bufsize, db_capture_inprogress;
154
155	if (kread_symbol(kvm, X_DB_CAPTURE_BUFOFF, &db_capture_bufoff,
156	    sizeof(db_capture_bufoff), 0) < 0)
157		errx(-1, "kvm: unable to read db_capture_bufoff");
158	if (kread_symbol(kvm, X_DB_CAPTURE_BUFSIZE, &db_capture_bufsize,
159	    sizeof(db_capture_bufsize), 0) < 0)
160		errx(-1, "kvm: unable to read db_capture_bufsize");
161	if (kread_symbol(kvm, X_DB_CAPTURE_INPROGRESS,
162	    &db_capture_inprogress, sizeof(db_capture_inprogress), 0) < 0)
163		err(-1, "kvm: unable to read db_capture_inprogress");
164	printf("%u/%u bytes used\n", db_capture_bufoff, db_capture_bufsize);
165	if (db_capture_inprogress)
166		printf("capture is on\n");
167	else
168		printf("capture is off\n");
169
170}
171
172static void
173ddb_capture_status_sysctl(void)
174{
175	u_int db_capture_bufoff, db_capture_bufsize, db_capture_inprogress;
176	size_t len;
177
178	len = sizeof(db_capture_bufoff);
179	if (sysctlbyname(SYSCTL_DDB_CAPTURE_BUFOFF, &db_capture_bufoff, &len,
180	    NULL, 0) < 0)
181		err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_BUFOFF);
182	len = sizeof(db_capture_bufoff);
183	if (sysctlbyname(SYSCTL_DDB_CAPTURE_BUFSIZE, &db_capture_bufsize,
184	    &len, NULL, 0) < 0)
185		err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_BUFSIZE);
186	len = sizeof(db_capture_inprogress);
187	if (sysctlbyname(SYSCTL_DDB_CAPTURE_INPROGRESS,
188	    &db_capture_inprogress, &len, NULL, 0) < 0)
189		err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_INPROGRESS);
190	printf("%u/%u bytes used\n", db_capture_bufoff, db_capture_bufsize);
191	if (db_capture_inprogress)
192		printf("capture is on\n");
193	else
194		printf("capture is off\n");
195}
196
197void
198ddb_capture(int argc, char *argv[])
199{
200	char *mflag, *nflag, errbuf[_POSIX2_LINE_MAX];
201	kvm_t *kvm;
202	int ch;
203
204	mflag = NULL;
205	nflag = NULL;
206	kvm = NULL;
207	while ((ch = getopt(argc, argv, "M:N:")) != -1) {
208		switch (ch) {
209		case 'M':
210			mflag = optarg;
211			break;
212
213		case 'N':
214			nflag = optarg;
215			break;
216
217		default:
218			usage();
219		}
220	}
221	argc -= optind;
222	argv += optind;
223
224	if (argc != 1)
225		usage();
226
227	if (mflag != NULL) {
228		kvm = kvm_openfiles(nflag, mflag, NULL, O_RDONLY, errbuf);
229		if (kvm == NULL)
230			errx(-1, "ddb_capture: kvm_openfiles: %s", errbuf);
231		if (kvm_nlist(kvm, namelist) != 0)
232			errx(-1, "ddb_capture: kvm_nlist");
233	} else if (nflag != NULL)
234		usage();
235	if (strcmp(argv[0], "print") == 0) {
236		if (kvm != NULL)
237			ddb_capture_print_kvm(kvm);
238		else
239			ddb_capture_print_sysctl();
240	} else if (strcmp(argv[0], "status") == 0) {
241		if (kvm != NULL)
242			ddb_capture_status_kvm(kvm);
243		else
244			ddb_capture_status_sysctl();
245	} else
246		usage();
247}
248