1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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/cdefs.h>
30 __FBSDID("$FreeBSD: stable/12/sbin/ddb/ddb_capture.c 335271 2018-06-17 00:00:24Z eadler $");
31
32 #include <sys/types.h>
33 #include <sys/sysctl.h>
34
35 #include <err.h>
36 #include <errno.h>
37 #include <fcntl.h>
38 #include <kvm.h>
39 #include <limits.h>
40 #include <stdio.h>
41 #include <stdlib.h>
42 #include <string.h>
43 #include <sysexits.h>
44 #include <unistd.h>
45
46 #include "ddb.h"
47
48 /*
49 * Interface with the ddb(4) capture buffer of a live kernel using sysctl, or
50 * for a crash dump using libkvm.
51 */
52 #define SYSCTL_DDB_CAPTURE_BUFOFF "debug.ddb.capture.bufoff"
53 #define SYSCTL_DDB_CAPTURE_BUFSIZE "debug.ddb.capture.bufsize"
54 #define SYSCTL_DDB_CAPTURE_MAXBUFSIZE "debug.ddb.capture.maxbufsize"
55 #define SYSCTL_DDB_CAPTURE_DATA "debug.ddb.capture.data"
56 #define SYSCTL_DDB_CAPTURE_INPROGRESS "debug.ddb.capture.inprogress"
57
58 static struct nlist namelist[] = {
59 #define X_DB_CAPTURE_BUF 0
60 { .n_name = "_db_capture_buf" },
61 #define X_DB_CAPTURE_BUFSIZE 1
62 { .n_name = "_db_capture_bufsize" },
63 #define X_DB_CAPTURE_MAXBUFSIZE 2
64 { .n_name = "_db_capture_maxbufsize" },
65 #define X_DB_CAPTURE_BUFOFF 3
66 { .n_name = "_db_capture_bufoff" },
67 #define X_DB_CAPTURE_INPROGRESS 4
68 { .n_name = "_db_capture_inprogress" },
69 { .n_name = "" },
70 };
71
72 static int
kread(kvm_t * kvm,void * kvm_pointer,void * address,size_t size,size_t offset)73 kread(kvm_t *kvm, void *kvm_pointer, void *address, size_t size,
74 size_t offset)
75 {
76 ssize_t ret;
77
78 ret = kvm_read(kvm, (unsigned long)kvm_pointer + offset, address,
79 size);
80 if (ret < 0 || (size_t)ret != size)
81 return (-1);
82 return (0);
83 }
84
85 static int
kread_symbol(kvm_t * kvm,int read_index,void * address,size_t size,size_t offset)86 kread_symbol(kvm_t *kvm, int read_index, void *address, size_t size,
87 size_t offset)
88 {
89 ssize_t ret;
90
91 ret = kvm_read(kvm, namelist[read_index].n_value + offset, address, size);
92 if (ret < 0 || (size_t)ret != size)
93 return (-1);
94 return (0);
95 }
96
97 static void
ddb_capture_print_kvm(kvm_t * kvm)98 ddb_capture_print_kvm(kvm_t *kvm)
99 {
100 u_int db_capture_bufoff;
101 char *buffer, *db_capture_buf;
102
103 if (kread_symbol(kvm, X_DB_CAPTURE_BUF, &db_capture_buf,
104 sizeof(db_capture_buf), 0) < 0)
105 errx(-1, "kvm: unable to read db_capture_buf");
106
107 if (kread_symbol(kvm, X_DB_CAPTURE_BUFOFF, &db_capture_bufoff,
108 sizeof(db_capture_bufoff), 0) < 0)
109 errx(-1, "kvm: unable to read db_capture_bufoff");
110
111 buffer = malloc(db_capture_bufoff + 1);
112 if (buffer == NULL)
113 err(-1, "malloc: db_capture_bufoff (%u)",
114 db_capture_bufoff);
115 bzero(buffer, db_capture_bufoff + 1);
116
117 if (kread(kvm, db_capture_buf, buffer, db_capture_bufoff, 0) < 0)
118 errx(-1, "kvm: unable to read buffer");
119
120 printf("%s\n", buffer);
121 free(buffer);
122 }
123
124 static void
ddb_capture_print_sysctl(void)125 ddb_capture_print_sysctl(void)
126 {
127 size_t buflen, len;
128 char *buffer;
129 int ret;
130
131 repeat:
132 if (sysctlbyname(SYSCTL_DDB_CAPTURE_DATA, NULL, &buflen, NULL, 0) < 0)
133 err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_DATA);
134 if (buflen == 0)
135 return;
136 buffer = malloc(buflen);
137 if (buffer == NULL)
138 err(EX_OSERR, "malloc");
139 bzero(buffer, buflen);
140 len = buflen;
141 ret = sysctlbyname(SYSCTL_DDB_CAPTURE_DATA, buffer, &len, NULL, 0);
142 if (ret < 0 && errno != ENOMEM)
143 err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_DATA);
144 if (ret < 0) {
145 free(buffer);
146 goto repeat;
147 }
148
149 printf("%s\n", buffer);
150 free(buffer);
151 }
152
153 static void
ddb_capture_status_kvm(kvm_t * kvm)154 ddb_capture_status_kvm(kvm_t *kvm)
155 {
156 u_int db_capture_bufoff, db_capture_bufsize, db_capture_inprogress;
157
158 if (kread_symbol(kvm, X_DB_CAPTURE_BUFOFF, &db_capture_bufoff,
159 sizeof(db_capture_bufoff), 0) < 0)
160 errx(-1, "kvm: unable to read db_capture_bufoff");
161 if (kread_symbol(kvm, X_DB_CAPTURE_BUFSIZE, &db_capture_bufsize,
162 sizeof(db_capture_bufsize), 0) < 0)
163 errx(-1, "kvm: unable to read db_capture_bufsize");
164 if (kread_symbol(kvm, X_DB_CAPTURE_INPROGRESS,
165 &db_capture_inprogress, sizeof(db_capture_inprogress), 0) < 0)
166 err(-1, "kvm: unable to read db_capture_inprogress");
167 printf("%u/%u bytes used\n", db_capture_bufoff, db_capture_bufsize);
168 if (db_capture_inprogress)
169 printf("capture is on\n");
170 else
171 printf("capture is off\n");
172
173 }
174
175 static void
ddb_capture_status_sysctl(void)176 ddb_capture_status_sysctl(void)
177 {
178 u_int db_capture_bufoff, db_capture_bufsize, db_capture_inprogress;
179 size_t len;
180
181 len = sizeof(db_capture_bufoff);
182 if (sysctlbyname(SYSCTL_DDB_CAPTURE_BUFOFF, &db_capture_bufoff, &len,
183 NULL, 0) < 0)
184 err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_BUFOFF);
185 len = sizeof(db_capture_bufoff);
186 if (sysctlbyname(SYSCTL_DDB_CAPTURE_BUFSIZE, &db_capture_bufsize,
187 &len, NULL, 0) < 0)
188 err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_BUFSIZE);
189 len = sizeof(db_capture_inprogress);
190 if (sysctlbyname(SYSCTL_DDB_CAPTURE_INPROGRESS,
191 &db_capture_inprogress, &len, NULL, 0) < 0)
192 err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_INPROGRESS);
193 printf("%u/%u bytes used\n", db_capture_bufoff, db_capture_bufsize);
194 if (db_capture_inprogress)
195 printf("capture is on\n");
196 else
197 printf("capture is off\n");
198 }
199
200 void
ddb_capture(int argc,char * argv[])201 ddb_capture(int argc, char *argv[])
202 {
203 char *mflag, *nflag, errbuf[_POSIX2_LINE_MAX];
204 kvm_t *kvm;
205 int ch;
206
207 mflag = NULL;
208 nflag = NULL;
209 kvm = NULL;
210 while ((ch = getopt(argc, argv, "M:N:")) != -1) {
211 switch (ch) {
212 case 'M':
213 mflag = optarg;
214 break;
215
216 case 'N':
217 nflag = optarg;
218 break;
219
220 default:
221 usage();
222 }
223 }
224 argc -= optind;
225 argv += optind;
226
227 if (argc != 1)
228 usage();
229
230 if (mflag != NULL) {
231 kvm = kvm_openfiles(nflag, mflag, NULL, O_RDONLY, errbuf);
232 if (kvm == NULL)
233 errx(-1, "ddb_capture: kvm_openfiles: %s", errbuf);
234 if (kvm_nlist(kvm, namelist) != 0)
235 errx(-1, "ddb_capture: kvm_nlist");
236 } else if (nflag != NULL)
237 usage();
238 if (strcmp(argv[0], "print") == 0) {
239 if (kvm != NULL)
240 ddb_capture_print_kvm(kvm);
241 else
242 ddb_capture_print_sysctl();
243 } else if (strcmp(argv[0], "status") == 0) {
244 if (kvm != NULL)
245 ddb_capture_status_kvm(kvm);
246 else
247 ddb_capture_status_sysctl();
248 } else
249 usage();
250 }
251