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 /*
119 * The default stack size limit in Linux is 8MB.
120 */
121 static void
122 linux_set_default_stacksize(struct thread *td, struct proc *p)
123 {
124 struct rlimit rlim;
125 int error;
126
127 if (linux_default_stacksize < 0)
128 return;
129
130 PROC_LOCK(p);
131 lim_rlimit_proc(p, RLIMIT_STACK, &rlim);
132 PROC_UNLOCK(p);
133 if (rlim.rlim_cur != rlim.rlim_max ||
134 rlim.rlim_cur <= linux_default_stacksize)
135 return;
136 rlim.rlim_cur = linux_default_stacksize;
137 error = kern_proc_setrlimit(td, p, RLIMIT_STACK, &rlim);
138 KASSERT(error == 0, ("kern_proc_setrlimit failed"));
139 }
140
141 void
142 linux_proc_init(struct thread *td, struct thread *newtd, int flags)
143 {
144 struct linux_emuldata *em;
145 struct linux_pemuldata *pem;
146 struct proc *p;
147
148 if (newtd != NULL) {
149 p = newtd->td_proc;
150
151 /* non-exec call */
152 em = malloc(sizeof(*em), M_TEMP, M_WAITOK | M_ZERO);
153 if (flags & LINUX_CLONE_THREAD) {
154 LINUX_CTR1(proc_init, "thread newtd(%d)",
155 newtd->td_tid);
156
157 em->em_tid = newtd->td_tid;
158 } else {
159 LINUX_CTR1(proc_init, "fork newtd(%d)", p->p_pid);
160
161 em->em_tid = p->p_pid;
162
163 pem = malloc(sizeof(*pem), M_LINUX, M_WAITOK | M_ZERO);
164 sx_init(&pem->pem_sx, "lpemlk");
165 p->p_emuldata = pem;
166 }
167 newtd->td_emuldata = em;
168
169 linux_set_default_openfiles(td, p);
170 linux_set_default_stacksize(td, p);
171 } else {
172 p = td->td_proc;
173
174 /* exec */
175 LINUX_CTR1(proc_init, "exec newtd(%d)", p->p_pid);
176
177 /* lookup the old one */
178 em = em_find(td);
179 KASSERT(em != NULL, ("proc_init: emuldata not found in exec case.\n"));
180
181 em->em_tid = p->p_pid;
182 em->flags = 0;
183 em->robust_futexes = NULL;
184 em->child_clear_tid = NULL;
185 em->child_set_tid = NULL;
186
187 pem = pem_find(p);
188 KASSERT(pem != NULL, ("proc_exit: proc emuldata not found.\n"));
189 pem->persona = 0;
190 }
191
192 }
193
194 void
195 linux_on_exit(struct proc *p)
196 {
197 struct linux_pemuldata *pem;
198 struct thread *td = curthread;
199
200 MPASS(SV_CURPROC_ABI() == SV_ABI_LINUX);
201
202 LINUX_CTR3(proc_exit, "thread(%d) proc(%d) p %p",
203 td->td_tid, p->p_pid, p);
204
205 pem = pem_find(p);
206 if (pem == NULL)
207 return;
208 (p->p_sysent->sv_thread_detach)(td);
209
210 p->p_emuldata = NULL;
211
212 sx_destroy(&pem->pem_sx);
213 free(pem, M_LINUX);
214 }
215
216 /*
217 * If a Linux binary is exec'ing something, try this image activator
218 * first. We override standard shell script execution in order to
219 * be able to modify the interpreter path. We only do this if a Linux
220 * binary is doing the exec, so we do not create an EXEC module for it.
221 */
222 int
223 linux_exec_imgact_try(struct image_params *imgp)
224 {
225 const char *head = (const char *)imgp->image_header;
226 char *rpath;
227 int error = -1;
228
229 /*
230 * The interpreter for shell scripts run from a Linux binary needs
231 * to be located in /compat/linux if possible in order to recursively
232 * maintain Linux path emulation.
233 */
234 if (((const short *)head)[0] == SHELLMAGIC) {
235 /*
236 * Run our normal shell image activator. If it succeeds attempt
237 * to use the alternate path for the interpreter. If an
238 * alternate path is found, use our stringspace to store it.
239 */
240 if ((error = exec_shell_imgact(imgp)) == 0) {
241 linux_emul_convpath(FIRST_THREAD_IN_PROC(imgp->proc),
242 imgp->interpreter_name, UIO_SYSSPACE, &rpath, 0,
243 AT_FDCWD);
244 if (rpath != NULL)
245 imgp->args->fname_buf =
246 imgp->interpreter_name = rpath;
247 }
248 }
249 return (error);
250 }
251
252 int
253 linux_common_execve(struct thread *td, struct image_args *eargs)
254 {
255 struct linux_pemuldata *pem;
256 struct vmspace *oldvmspace;
257 struct linux_emuldata *em;
258 struct proc *p;
259 int error;
260
261 p = td->td_proc;
262
263 error = pre_execve(td, &oldvmspace);
264 if (error != 0)
265 return (error);
266
267 error = kern_execve(td, eargs, NULL, oldvmspace);
268 post_execve(td, error, oldvmspace);
269 if (error != EJUSTRETURN)
270 return (error);
271
272 /*
273 * In a case of transition from Linux binary execing to
274 * FreeBSD binary we destroy Linux emuldata thread & proc entries.
275 */
276 if (SV_CURPROC_ABI() != SV_ABI_LINUX) {
277 PROC_LOCK(p);
278 em = em_find(td);
279 KASSERT(em != NULL, ("proc_exec: thread emuldata not found.\n"));
280 td->td_emuldata = NULL;
281
282 pem = pem_find(p);
283 KASSERT(pem != NULL, ("proc_exec: proc pemuldata not found.\n"));
284 p->p_emuldata = NULL;
285 PROC_UNLOCK(p);
286
287 free(em, M_TEMP);
288 free(pem, M_LINUX);
289 }
290 return (EJUSTRETURN);
291 }
292
293 void
294 linux_on_exec(struct proc *p, struct image_params *imgp)
295 {
296 struct thread *td;
297 struct thread *othertd;
298 #if defined(__amd64__)
299 struct linux_pemuldata *pem;
300 #endif
301
302 td = curthread;
303 MPASS((imgp->sysent->sv_flags & SV_ABI_MASK) == SV_ABI_LINUX);
304
305 /*
306 * When execing to Linux binary, we create Linux emuldata
307 * thread entry.
308 */
309 if (SV_PROC_ABI(p) == SV_ABI_LINUX) {
310 /*
311 * Process already was under Linuxolator
312 * before exec. Update emuldata to reflect
313 * single-threaded cleaned state after exec.
314 */
315 linux_proc_init(td, NULL, 0);
316 } else {
317 /*
318 * We are switching the process to Linux emulator.
319 */
320 linux_proc_init(td, td, 0);
321
322 /*
323 * Create a transient td_emuldata for all suspended
324 * threads, so that p->p_sysent->sv_thread_detach() ==
325 * linux_thread_detach() can find expected but unused
326 * emuldata.
327 */
328 FOREACH_THREAD_IN_PROC(td->td_proc, othertd) {
329 if (othertd == td)
330 continue;
331 linux_proc_init(td, othertd, LINUX_CLONE_THREAD);
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 void
348 linux_thread_dtor(struct thread *td)
349 {
350 struct linux_emuldata *em;
351
352 em = em_find(td);
353 if (em == NULL)
354 return;
355 td->td_emuldata = NULL;
356
357 LINUX_CTR1(thread_dtor, "thread(%d)", em->em_tid);
358
359 free(em, M_TEMP);
360 }
361
362 void
363 linux_schedtail(struct thread *td)
364 {
365 struct linux_emuldata *em;
366 struct proc *p;
367 int error = 0;
368 int *child_set_tid;
369
370 p = td->td_proc;
371
372 em = em_find(td);
373 KASSERT(em != NULL, ("linux_schedtail: thread emuldata not found.\n"));
374 child_set_tid = em->child_set_tid;
375
376 if (child_set_tid != NULL) {
377 error = copyout(&em->em_tid, child_set_tid,
378 sizeof(em->em_tid));
379 LINUX_CTR4(schedtail, "thread(%d) %p stored %d error %d",
380 td->td_tid, child_set_tid, em->em_tid, error);
381 } else
382 LINUX_CTR1(schedtail, "thread(%d)", em->em_tid);
383 }
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