1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2009 Robert N. M. Watson
5 * Copyright (c) 2009 Bjoern A. Zeeb <bz@FreeBSD.org>
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD: stable/12/lib/libkvm/kvm_vnet.c 326219 2017-11-26 02:00:33Z pfg $");
32
33 #include <sys/param.h>
34
35 #define _WANT_PRISON
36 #define _WANT_UCRED
37 #define _WANT_VNET
38
39 #include <sys/_lock.h>
40 #include <sys/_mutex.h>
41 #include <sys/_task.h>
42 #include <sys/jail.h>
43 #include <sys/proc.h>
44 #include <sys/types.h>
45
46 #include <net/vnet.h>
47
48 #include <kvm.h>
49 #include <limits.h>
50 #include <stdlib.h>
51 #include <unistd.h>
52
53 #include "kvm_private.h"
54
55 /*
56 * Set up libkvm to handle virtual network stack symbols by selecting a
57 * starting pid.
58 */
59 int
_kvm_vnet_selectpid(kvm_t * kd,pid_t pid)60 _kvm_vnet_selectpid(kvm_t *kd, pid_t pid)
61 {
62 struct proc proc;
63 struct ucred cred;
64 struct prison prison;
65 struct vnet vnet;
66 struct kvm_nlist nl[] = {
67 /*
68 * Note: kvm_nlist strips the first '_' so add an extra one
69 * here to __{start,stop}_set_vnet.
70 */
71 #define NLIST_START_VNET 0
72 { .n_name = "___start_" VNET_SETNAME },
73 #define NLIST_STOP_VNET 1
74 { .n_name = "___stop_" VNET_SETNAME },
75 #define NLIST_VNET_HEAD 2
76 { .n_name = "vnet_head" },
77 #define NLIST_ALLPROC 3
78 { .n_name = "allproc" },
79 #define NLIST_DUMPTID 4
80 { .n_name = "dumptid" },
81 #define NLIST_PROC0 5
82 { .n_name = "proc0" },
83 { .n_name = NULL },
84 };
85 uintptr_t procp, credp;
86 #define VMCORE_VNET_OF_PROC0
87 #ifndef VMCORE_VNET_OF_PROC0
88 struct thread td;
89 uintptr_t tdp;
90 #endif
91 lwpid_t dumptid;
92
93 /*
94 * XXX: This only works for native kernels for now.
95 */
96 if (!kvm_native(kd))
97 return (-1);
98
99 /*
100 * Locate and cache locations of important symbols
101 * using the internal version of _kvm_nlist, turning
102 * off initialization to avoid recursion in case of
103 * unresolveable symbols.
104 */
105 if (_kvm_nlist(kd, nl, 0) != 0) {
106 /*
107 * XXX-BZ: ___start_/___stop_VNET_SETNAME may fail.
108 * For now do not report an error here as we are called
109 * internally and in `void context' until we merge the
110 * functionality to optionally activate this into programs.
111 * By that time we can properly fail and let the callers
112 * handle the error.
113 */
114 /* _kvm_err(kd, kd->program, "%s: no namelist", __func__); */
115 return (-1);
116 }
117
118 /*
119 * Auto-detect if this is a crashdump by reading dumptid.
120 */
121 dumptid = 0;
122 if (nl[NLIST_DUMPTID].n_value) {
123 if (kvm_read(kd, nl[NLIST_DUMPTID].n_value, &dumptid,
124 sizeof(dumptid)) != sizeof(dumptid)) {
125 _kvm_err(kd, kd->program, "%s: dumptid", __func__);
126 return (-1);
127 }
128 }
129
130 /*
131 * First, find the process for this pid. If we are working on a
132 * dump, either locate the thread dumptid is referring to or proc0.
133 * Based on either, take the address of the ucred.
134 */
135 credp = 0;
136
137 procp = nl[NLIST_ALLPROC].n_value;
138 #ifdef VMCORE_VNET_OF_PROC0
139 if (dumptid > 0) {
140 procp = nl[NLIST_PROC0].n_value;
141 pid = 0;
142 }
143 #endif
144 while (procp != 0) {
145 if (kvm_read(kd, procp, &proc, sizeof(proc)) != sizeof(proc)) {
146 _kvm_err(kd, kd->program, "%s: proc", __func__);
147 return (-1);
148 }
149 #ifndef VMCORE_VNET_OF_PROC0
150 if (dumptid > 0) {
151 tdp = (uintptr_t)TAILQ_FIRST(&proc.p_threads);
152 while (tdp != 0) {
153 if (kvm_read(kd, tdp, &td, sizeof(td)) !=
154 sizeof(td)) {
155 _kvm_err(kd, kd->program, "%s: thread",
156 __func__);
157 return (-1);
158 }
159 if (td.td_tid == dumptid) {
160 credp = (uintptr_t)td.td_ucred;
161 break;
162 }
163 tdp = (uintptr_t)TAILQ_NEXT(&td, td_plist);
164 }
165 } else
166 #endif
167 if (proc.p_pid == pid)
168 credp = (uintptr_t)proc.p_ucred;
169 if (credp != 0)
170 break;
171 procp = (uintptr_t)LIST_NEXT(&proc, p_list);
172 }
173 if (credp == 0) {
174 _kvm_err(kd, kd->program, "%s: pid/tid not found", __func__);
175 return (-1);
176 }
177 if (kvm_read(kd, (uintptr_t)credp, &cred, sizeof(cred)) !=
178 sizeof(cred)) {
179 _kvm_err(kd, kd->program, "%s: cred", __func__);
180 return (-1);
181 }
182 if (cred.cr_prison == NULL) {
183 _kvm_err(kd, kd->program, "%s: no jail", __func__);
184 return (-1);
185 }
186 if (kvm_read(kd, (uintptr_t)cred.cr_prison, &prison, sizeof(prison)) !=
187 sizeof(prison)) {
188 _kvm_err(kd, kd->program, "%s: prison", __func__);
189 return (-1);
190 }
191 if (prison.pr_vnet == NULL) {
192 _kvm_err(kd, kd->program, "%s: no vnet", __func__);
193 return (-1);
194 }
195 if (kvm_read(kd, (uintptr_t)prison.pr_vnet, &vnet, sizeof(vnet)) !=
196 sizeof(vnet)) {
197 _kvm_err(kd, kd->program, "%s: vnet", __func__);
198 return (-1);
199 }
200 if (vnet.vnet_magic_n != VNET_MAGIC_N) {
201 _kvm_err(kd, kd->program, "%s: invalid vnet magic#", __func__);
202 return (-1);
203 }
204 kd->vnet_initialized = 1;
205 kd->vnet_start = nl[NLIST_START_VNET].n_value;
206 kd->vnet_stop = nl[NLIST_STOP_VNET].n_value;
207 kd->vnet_current = (uintptr_t)prison.pr_vnet;
208 kd->vnet_base = vnet.vnet_data_base;
209 return (0);
210 }
211
212 /*
213 * Check whether the vnet module has been initialized successfully
214 * or not, initialize it if permitted.
215 */
216 int
_kvm_vnet_initialized(kvm_t * kd,int intialize)217 _kvm_vnet_initialized(kvm_t *kd, int intialize)
218 {
219
220 if (kd->vnet_initialized || !intialize)
221 return (kd->vnet_initialized);
222
223 (void) _kvm_vnet_selectpid(kd, getpid());
224
225 return (kd->vnet_initialized);
226 }
227
228 /*
229 * Check whether the value is within the vnet symbol range and
230 * only if so adjust the offset relative to the current base.
231 */
232 kvaddr_t
_kvm_vnet_validaddr(kvm_t * kd,kvaddr_t value)233 _kvm_vnet_validaddr(kvm_t *kd, kvaddr_t value)
234 {
235
236 if (value == 0)
237 return (value);
238
239 if (!kd->vnet_initialized)
240 return (value);
241
242 if (value < kd->vnet_start || value >= kd->vnet_stop)
243 return (value);
244
245 return (kd->vnet_base + value);
246 }
247