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("$FreeBSD$");
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/resourcevar.h>
46 #include <sys/syscallsubr.h>
47 #include <sys/sysent.h>
48
49 #include <compat/linux/linux_emul.h>
50 #include <compat/linux/linux_mib.h>
51 #include <compat/linux/linux_misc.h>
52 #include <compat/linux/linux_persona.h>
53 #include <compat/linux/linux_util.h>
54
55 #if BYTE_ORDER == LITTLE_ENDIAN
56 #define SHELLMAGIC 0x2123 /* #! */
57 #else
58 #define SHELLMAGIC 0x2321
59 #endif
60
61 /*
62 * This returns reference to the thread emuldata entry (if found)
63 *
64 * Hold PROC_LOCK when referencing emuldata from other threads.
65 */
66 struct linux_emuldata *
67 em_find(struct thread *td)
68 {
69 struct linux_emuldata *em;
70
71 em = td->td_emuldata;
72
73 return (em);
74 }
75
76 /*
77 * This returns reference to the proc pemuldata entry (if found)
78 *
79 * Hold PROC_LOCK when referencing proc pemuldata from other threads.
80 * Hold LINUX_PEM_LOCK wher referencing pemuldata members.
81 */
82 struct linux_pemuldata *
83 pem_find(struct proc *p)
84 {
85 struct linux_pemuldata *pem;
86
87 pem = p->p_emuldata;
88
89 return (pem);
90 }
91
92 /*
93 * Linux apps generally expect the soft open file limit to be set
94 * to 1024, often iterating over all the file descriptors up to that
95 * limit instead of using closefrom(2). Give them what they want,
96 * unless there already is a resource limit in place.
97 */
98 static void
99 linux_set_default_openfiles(struct thread *td, struct proc *p)
100 {
101 struct rlimit rlim;
102 int error;
103
104 if (linux_default_openfiles < 0)
105 return;
106
107 PROC_LOCK(p);
108 lim_rlimit_proc(p, RLIMIT_NOFILE, &rlim);
109 PROC_UNLOCK(p);
110 if (rlim.rlim_cur != rlim.rlim_max ||
111 rlim.rlim_cur <= linux_default_openfiles)
112 return;
113 rlim.rlim_cur = linux_default_openfiles;
114 error = kern_proc_setrlimit(td, p, RLIMIT_NOFILE, &rlim);
115 KASSERT(error == 0, ("kern_proc_setrlimit failed"));
116 }
117
118 void
119 linux_proc_init(struct thread *td, struct thread *newtd, int flags)
120 {
121 struct linux_emuldata *em;
122 struct linux_pemuldata *pem;
123 struct epoll_emuldata *emd;
124 struct proc *p;
125
126 if (newtd != NULL) {
127 p = newtd->td_proc;
128
129 /* non-exec call */
130 em = malloc(sizeof(*em), M_TEMP, M_WAITOK | M_ZERO);
131 if (flags & LINUX_CLONE_THREAD) {
132 LINUX_CTR1(proc_init, "thread newtd(%d)",
133 newtd->td_tid);
134
135 em->em_tid = newtd->td_tid;
136 } else {
137 LINUX_CTR1(proc_init, "fork newtd(%d)", p->p_pid);
138
139 em->em_tid = p->p_pid;
140
141 pem = malloc(sizeof(*pem), M_LINUX, M_WAITOK | M_ZERO);
142 sx_init(&pem->pem_sx, "lpemlk");
143 p->p_emuldata = pem;
144 }
145 newtd->td_emuldata = em;
146
147 linux_set_default_openfiles(td, p);
148 } else {
149 p = td->td_proc;
150
151 /* exec */
152 LINUX_CTR1(proc_init, "exec newtd(%d)", p->p_pid);
153
154 /* lookup the old one */
155 em = em_find(td);
156 KASSERT(em != NULL, ("proc_init: emuldata not found in exec case.\n"));
157
158 em->em_tid = p->p_pid;
159 em->flags = 0;
160 em->robust_futexes = NULL;
161 em->child_clear_tid = NULL;
162 em->child_set_tid = NULL;
163
164 /* epoll should be destroyed in a case of exec. */
165 pem = pem_find(p);
166 KASSERT(pem != NULL, ("proc_exit: proc emuldata not found.\n"));
167 pem->persona = 0;
168 if (pem->epoll != NULL) {
169 emd = pem->epoll;
170 pem->epoll = NULL;
171 free(emd, M_EPOLL);
172 }
173 }
174
175 }
176
177 void
178 linux_proc_exit(void *arg __unused, struct proc *p)
179 {
180 struct linux_pemuldata *pem;
181 struct epoll_emuldata *emd;
182 struct thread *td = curthread;
183
184 if (__predict_false(SV_CURPROC_ABI() != SV_ABI_LINUX))
185 return;
186
187 LINUX_CTR3(proc_exit, "thread(%d) proc(%d) p %p",
188 td->td_tid, p->p_pid, p);
189
190 pem = pem_find(p);
191 if (pem == NULL)
192 return;
193 (p->p_sysent->sv_thread_detach)(td);
194
195 p->p_emuldata = NULL;
196
197 if (pem->epoll != NULL) {
198 emd = pem->epoll;
199 pem->epoll = NULL;
200 free(emd, M_EPOLL);
201 }
202
203 sx_destroy(&pem->pem_sx);
204 free(pem, M_LINUX);
205 }
206
207 /*
208 * If a Linux binary is exec'ing something, try this image activator
209 * first. We override standard shell script execution in order to
210 * be able to modify the interpreter path. We only do this if a Linux
211 * binary is doing the exec, so we do not create an EXEC module for it.
212 */
213 int
214 linux_exec_imgact_try(struct image_params *imgp)
215 {
216 const char *head = (const char *)imgp->image_header;
217 char *rpath;
218 int error = -1;
219
220 /*
221 * The interpreter for shell scripts run from a Linux binary needs
222 * to be located in /compat/linux if possible in order to recursively
223 * maintain Linux path emulation.
224 */
225 if (((const short *)head)[0] == SHELLMAGIC) {
226 /*
227 * Run our normal shell image activator. If it succeeds attempt
228 * to use the alternate path for the interpreter. If an
229 * alternate path is found, use our stringspace to store it.
230 */
231 if ((error = exec_shell_imgact(imgp)) == 0) {
232 linux_emul_convpath(FIRST_THREAD_IN_PROC(imgp->proc),
233 imgp->interpreter_name, UIO_SYSSPACE, &rpath, 0,
234 AT_FDCWD);
235 if (rpath != NULL)
236 imgp->args->fname_buf =
237 imgp->interpreter_name = rpath;
238 }
239 }
240 return (error);
241 }
242
243 int
244 linux_common_execve(struct thread *td, struct image_args *eargs)
245 {
246 struct linux_pemuldata *pem;
247 struct epoll_emuldata *emd;
248 struct vmspace *oldvmspace;
249 struct linux_emuldata *em;
250 struct proc *p;
251 int error;
252
253 p = td->td_proc;
254
255 error = pre_execve(td, &oldvmspace);
256 if (error != 0)
257 return (error);
258
259 error = kern_execve(td, eargs, NULL, oldvmspace);
260 post_execve(td, error, oldvmspace);
261 if (error != EJUSTRETURN)
262 return (error);
263
264 /*
265 * In a case of transition from Linux binary execing to
266 * FreeBSD binary we destroy Linux emuldata thread & proc entries.
267 */
268 if (SV_CURPROC_ABI() != SV_ABI_LINUX) {
269 PROC_LOCK(p);
270 em = em_find(td);
271 KASSERT(em != NULL, ("proc_exec: thread emuldata not found.\n"));
272 td->td_emuldata = NULL;
273
274 pem = pem_find(p);
275 KASSERT(pem != NULL, ("proc_exec: proc pemuldata not found.\n"));
276 p->p_emuldata = NULL;
277 PROC_UNLOCK(p);
278
279 if (pem->epoll != NULL) {
280 emd = pem->epoll;
281 pem->epoll = NULL;
282 free(emd, M_EPOLL);
283 }
284
285 free(em, M_TEMP);
286 free(pem, M_LINUX);
287 }
288 return (EJUSTRETURN);
289 }
290
291 void
292 linux_proc_exec(void *arg __unused, struct proc *p, struct image_params *imgp)
293 {
294 struct thread *td;
295 struct thread *othertd;
296 #if defined(__amd64__)
297 struct linux_pemuldata *pem;
298 #endif
299
300 td = curthread;
301
302 /*
303 * In a case of execing to Linux binary we create Linux
304 * emuldata thread entry.
305 */
306 if (__predict_false((imgp->sysent->sv_flags & SV_ABI_MASK) ==
307 SV_ABI_LINUX)) {
308 if (SV_PROC_ABI(p) == SV_ABI_LINUX) {
309 /*
310 * Process already was under Linuxolator
311 * before exec. Update emuldata to reflect
312 * single-threaded cleaned state after exec.
313 */
314 linux_proc_init(td, NULL, 0);
315 } else {
316 /*
317 * We are switching the process to Linux emulator.
318 */
319 linux_proc_init(td, td, 0);
320
321 /*
322 * Create a transient td_emuldata for all suspended
323 * threads, so that p->p_sysent->sv_thread_detach() ==
324 * linux_thread_detach() can find expected but unused
325 * emuldata.
326 */
327 FOREACH_THREAD_IN_PROC(td->td_proc, othertd) {
328 if (othertd != td) {
329 linux_proc_init(td, othertd,
330 LINUX_CLONE_THREAD);
331 }
332 }
333 }
334 #if defined(__amd64__)
335 /*
336 * An IA32 executable which has executable stack will have the
337 * READ_IMPLIES_EXEC personality flag set automatically.
338 */
339 if (SV_PROC_FLAG(td->td_proc, SV_ILP32) &&
340 imgp->stack_prot & VM_PROT_EXECUTE) {
341 pem = pem_find(p);
342 pem->persona |= LINUX_READ_IMPLIES_EXEC;
343 }
344 #endif
345 }
346 }
347
348 void
349 linux_thread_dtor(void *arg __unused, struct thread *td)
350 {
351 struct linux_emuldata *em;
352
353 em = em_find(td);
354 if (em == NULL)
355 return;
356 td->td_emuldata = NULL;
357
358 LINUX_CTR1(thread_dtor, "thread(%d)", em->em_tid);
359
360 free(em, M_TEMP);
361 }
362
363 void
364 linux_schedtail(struct thread *td)
365 {
366 struct linux_emuldata *em;
367 struct proc *p;
368 int error = 0;
369 int *child_set_tid;
370
371 p = td->td_proc;
372
373 em = em_find(td);
374 KASSERT(em != NULL, ("linux_schedtail: thread emuldata not found.\n"));
375 child_set_tid = em->child_set_tid;
376
377 if (child_set_tid != NULL) {
378 error = copyout(&em->em_tid, child_set_tid,
379 sizeof(em->em_tid));
380 LINUX_CTR4(schedtail, "thread(%d) %p stored %d error %d",
381 td->td_tid, child_set_tid, em->em_tid, error);
382 } else
383 LINUX_CTR1(schedtail, "thread(%d)", em->em_tid);
384 }
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