1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 1994-1996 Søren Schmidt
5 * Copyright (c) 2006 Roman Divacky
6 * Copyright (c) 2013 Dmitry Chagin
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31 #include <sys/cdefs.h>
32 __FBSDID("$FreeBSD: releng/12.0/sys/compat/linux/linux_emul.c 332333 2018-04-09 17:24:01Z emaste $");
33
34 #include <sys/param.h>
35 #include <sys/systm.h>
36 #include <sys/fcntl.h>
37 #include <sys/imgact.h>
38 #include <sys/kernel.h>
39 #include <sys/ktr.h>
40 #include <sys/lock.h>
41 #include <sys/malloc.h>
42 #include <sys/mutex.h>
43 #include <sys/sx.h>
44 #include <sys/proc.h>
45 #include <sys/syscallsubr.h>
46 #include <sys/sysent.h>
47
48 #include <compat/linux/linux_emul.h>
49 #include <compat/linux/linux_misc.h>
50 #include <compat/linux/linux_persona.h>
51 #include <compat/linux/linux_util.h>
52
53 #if BYTE_ORDER == LITTLE_ENDIAN
54 #define SHELLMAGIC 0x2123 /* #! */
55 #else
56 #define SHELLMAGIC 0x2321
57 #endif
58
59 /*
60 * This returns reference to the thread emuldata entry (if found)
61 *
62 * Hold PROC_LOCK when referencing emuldata from other threads.
63 */
64 struct linux_emuldata *
65 em_find(struct thread *td)
66 {
67 struct linux_emuldata *em;
68
69 em = td->td_emuldata;
70
71 return (em);
72 }
73
74 /*
75 * This returns reference to the proc pemuldata entry (if found)
76 *
77 * Hold PROC_LOCK when referencing proc pemuldata from other threads.
78 * Hold LINUX_PEM_LOCK wher referencing pemuldata members.
79 */
80 struct linux_pemuldata *
81 pem_find(struct proc *p)
82 {
83 struct linux_pemuldata *pem;
84
85 pem = p->p_emuldata;
86
87 return (pem);
88 }
89
90 void
91 linux_proc_init(struct thread *td, struct thread *newtd, int flags)
92 {
93 struct linux_emuldata *em;
94 struct linux_pemuldata *pem;
95 struct epoll_emuldata *emd;
96 struct proc *p;
97
98 if (newtd != NULL) {
99 p = newtd->td_proc;
100
101 /* non-exec call */
102 em = malloc(sizeof(*em), M_TEMP, M_WAITOK | M_ZERO);
103 if (flags & LINUX_CLONE_THREAD) {
104 LINUX_CTR1(proc_init, "thread newtd(%d)",
105 newtd->td_tid);
106
107 em->em_tid = newtd->td_tid;
108 } else {
109 LINUX_CTR1(proc_init, "fork newtd(%d)", p->p_pid);
110
111 em->em_tid = p->p_pid;
112
113 pem = malloc(sizeof(*pem), M_LINUX, M_WAITOK | M_ZERO);
114 sx_init(&pem->pem_sx, "lpemlk");
115 p->p_emuldata = pem;
116 }
117 newtd->td_emuldata = em;
118 } else {
119 p = td->td_proc;
120
121 /* exec */
122 LINUX_CTR1(proc_init, "exec newtd(%d)", p->p_pid);
123
124 /* lookup the old one */
125 em = em_find(td);
126 KASSERT(em != NULL, ("proc_init: emuldata not found in exec case.\n"));
127
128 em->em_tid = p->p_pid;
129 em->flags = 0;
130 em->pdeath_signal = 0;
131 em->robust_futexes = NULL;
132 em->child_clear_tid = NULL;
133 em->child_set_tid = NULL;
134
135 /* epoll should be destroyed in a case of exec. */
136 pem = pem_find(p);
137 KASSERT(pem != NULL, ("proc_exit: proc emuldata not found.\n"));
138 pem->persona = 0;
139 if (pem->epoll != NULL) {
140 emd = pem->epoll;
141 pem->epoll = NULL;
142 free(emd, M_EPOLL);
143 }
144 }
145
146 }
147
148 void
149 linux_proc_exit(void *arg __unused, struct proc *p)
150 {
151 struct linux_pemuldata *pem;
152 struct epoll_emuldata *emd;
153 struct thread *td = curthread;
154
155 if (__predict_false(SV_CURPROC_ABI() != SV_ABI_LINUX))
156 return;
157
158 LINUX_CTR3(proc_exit, "thread(%d) proc(%d) p %p",
159 td->td_tid, p->p_pid, p);
160
161 pem = pem_find(p);
162 if (pem == NULL)
163 return;
164 (p->p_sysent->sv_thread_detach)(td);
165
166 p->p_emuldata = NULL;
167
168 if (pem->epoll != NULL) {
169 emd = pem->epoll;
170 pem->epoll = NULL;
171 free(emd, M_EPOLL);
172 }
173
174 sx_destroy(&pem->pem_sx);
175 free(pem, M_LINUX);
176 }
177
178 /*
179 * If a Linux binary is exec'ing something, try this image activator
180 * first. We override standard shell script execution in order to
181 * be able to modify the interpreter path. We only do this if a Linux
182 * binary is doing the exec, so we do not create an EXEC module for it.
183 */
184 int
185 linux_exec_imgact_try(struct image_params *imgp)
186 {
187 const char *head = (const char *)imgp->image_header;
188 char *rpath;
189 int error = -1;
190
191 /*
192 * The interpreter for shell scripts run from a Linux binary needs
193 * to be located in /compat/linux if possible in order to recursively
194 * maintain Linux path emulation.
195 */
196 if (((const short *)head)[0] == SHELLMAGIC) {
197 /*
198 * Run our normal shell image activator. If it succeeds attempt
199 * to use the alternate path for the interpreter. If an
200 * alternate path is found, use our stringspace to store it.
201 */
202 if ((error = exec_shell_imgact(imgp)) == 0) {
203 linux_emul_convpath(FIRST_THREAD_IN_PROC(imgp->proc),
204 imgp->interpreter_name, UIO_SYSSPACE, &rpath, 0,
205 AT_FDCWD);
206 if (rpath != NULL)
207 imgp->args->fname_buf =
208 imgp->interpreter_name = rpath;
209 }
210 }
211 return (error);
212 }
213
214 int
215 linux_common_execve(struct thread *td, struct image_args *eargs)
216 {
217 struct linux_pemuldata *pem;
218 struct epoll_emuldata *emd;
219 struct vmspace *oldvmspace;
220 struct linux_emuldata *em;
221 struct proc *p;
222 int error;
223
224 p = td->td_proc;
225
226 error = pre_execve(td, &oldvmspace);
227 if (error != 0)
228 return (error);
229
230 error = kern_execve(td, eargs, NULL);
231 post_execve(td, error, oldvmspace);
232 if (error != EJUSTRETURN)
233 return (error);
234
235 /*
236 * In a case of transition from Linux binary execing to
237 * FreeBSD binary we destroy Linux emuldata thread & proc entries.
238 */
239 if (SV_CURPROC_ABI() != SV_ABI_LINUX) {
240 PROC_LOCK(p);
241 em = em_find(td);
242 KASSERT(em != NULL, ("proc_exec: thread emuldata not found.\n"));
243 td->td_emuldata = NULL;
244
245 pem = pem_find(p);
246 KASSERT(pem != NULL, ("proc_exec: proc pemuldata not found.\n"));
247 p->p_emuldata = NULL;
248 PROC_UNLOCK(p);
249
250 if (pem->epoll != NULL) {
251 emd = pem->epoll;
252 pem->epoll = NULL;
253 free(emd, M_EPOLL);
254 }
255
256 free(em, M_TEMP);
257 free(pem, M_LINUX);
258 }
259 return (EJUSTRETURN);
260 }
261
262 void
263 linux_proc_exec(void *arg __unused, struct proc *p, struct image_params *imgp)
264 {
265 struct thread *td = curthread;
266 struct thread *othertd;
267 #if defined(__amd64__)
268 struct linux_pemuldata *pem;
269 #endif
270
271 /*
272 * In a case of execing from Linux binary properly detach
273 * other threads from the user space.
274 */
275 if (__predict_false(SV_PROC_ABI(p) == SV_ABI_LINUX)) {
276 FOREACH_THREAD_IN_PROC(p, othertd) {
277 if (td != othertd)
278 (p->p_sysent->sv_thread_detach)(othertd);
279 }
280 }
281
282 /*
283 * In a case of execing to Linux binary we create Linux
284 * emuldata thread entry.
285 */
286 if (__predict_false((imgp->sysent->sv_flags & SV_ABI_MASK) ==
287 SV_ABI_LINUX)) {
288
289 if (SV_PROC_ABI(p) == SV_ABI_LINUX)
290 linux_proc_init(td, NULL, 0);
291 else
292 linux_proc_init(td, td, 0);
293 #if defined(__amd64__)
294 /*
295 * An IA32 executable which has executable stack will have the
296 * READ_IMPLIES_EXEC personality flag set automatically.
297 */
298 if (SV_PROC_FLAG(td->td_proc, SV_ILP32) &&
299 imgp->stack_prot & VM_PROT_EXECUTE) {
300 pem = pem_find(p);
301 pem->persona |= LINUX_READ_IMPLIES_EXEC;
302 }
303 #endif
304 }
305 }
306
307 void
308 linux_thread_dtor(void *arg __unused, struct thread *td)
309 {
310 struct linux_emuldata *em;
311
312 em = em_find(td);
313 if (em == NULL)
314 return;
315 td->td_emuldata = NULL;
316
317 LINUX_CTR1(thread_dtor, "thread(%d)", em->em_tid);
318
319 free(em, M_TEMP);
320 }
321
322 void
323 linux_schedtail(struct thread *td)
324 {
325 struct linux_emuldata *em;
326 struct proc *p;
327 int error = 0;
328 int *child_set_tid;
329
330 p = td->td_proc;
331
332 em = em_find(td);
333 KASSERT(em != NULL, ("linux_schedtail: thread emuldata not found.\n"));
334 child_set_tid = em->child_set_tid;
335
336 if (child_set_tid != NULL) {
337 error = copyout(&em->em_tid, child_set_tid,
338 sizeof(em->em_tid));
339 LINUX_CTR4(schedtail, "thread(%d) %p stored %d error %d",
340 td->td_tid, child_set_tid, em->em_tid, error);
341 } else
342 LINUX_CTR1(schedtail, "thread(%d)", em->em_tid);
343 }
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