linux_emul.c

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    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/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->robust_futexes = NULL;
  131                 em->child_clear_tid = NULL;
  132                 em->child_set_tid = NULL;
  133 
  134                  /* epoll should be destroyed in a case of exec. */
  135                 pem = pem_find(p);
  136                 KASSERT(pem != NULL, ("proc_exit: proc emuldata not found.\n"));
  137                 pem->persona = 0;
  138                 if (pem->epoll != NULL) {
  139                         emd = pem->epoll;
  140                         pem->epoll = NULL;
  141                         free(emd, M_EPOLL);
  142                 }
  143         }
  144 
  145 }
  146 
  147 void
  148 linux_proc_exit(void *arg __unused, struct proc *p)
  149 {
  150         struct linux_pemuldata *pem;
  151         struct epoll_emuldata *emd;
  152         struct thread *td = curthread;
  153 
  154         if (__predict_false(SV_CURPROC_ABI() != SV_ABI_LINUX))
  155                 return;
  156 
  157         LINUX_CTR3(proc_exit, "thread(%d) proc(%d) p %p",
  158             td->td_tid, p->p_pid, p);
  159 
  160         pem = pem_find(p);
  161         if (pem == NULL)
  162                 return;
  163         (p->p_sysent->sv_thread_detach)(td);
  164 
  165         p->p_emuldata = NULL;
  166 
  167         if (pem->epoll != NULL) {
  168                 emd = pem->epoll;
  169                 pem->epoll = NULL;
  170                 free(emd, M_EPOLL);
  171         }
  172 
  173         sx_destroy(&pem->pem_sx);
  174         free(pem, M_LINUX);
  175 }
  176 
  177 /*
  178  * If a Linux binary is exec'ing something, try this image activator
  179  * first.  We override standard shell script execution in order to
  180  * be able to modify the interpreter path.  We only do this if a Linux
  181  * binary is doing the exec, so we do not create an EXEC module for it.
  182  */
  183 int
  184 linux_exec_imgact_try(struct image_params *imgp)
  185 {
  186         const char *head = (const char *)imgp->image_header;
  187         char *rpath;
  188         int error = -1;
  189 
  190         /*
  191          * The interpreter for shell scripts run from a Linux binary needs
  192          * to be located in /compat/linux if possible in order to recursively
  193          * maintain Linux path emulation.
  194          */
  195         if (((const short *)head)[0] == SHELLMAGIC) {
  196                 /*
  197                  * Run our normal shell image activator.  If it succeeds attempt
  198                  * to use the alternate path for the interpreter.  If an
  199                  * alternate path is found, use our stringspace to store it.
  200                  */
  201                 if ((error = exec_shell_imgact(imgp)) == 0) {
  202                         linux_emul_convpath(FIRST_THREAD_IN_PROC(imgp->proc),
  203                             imgp->interpreter_name, UIO_SYSSPACE, &rpath, 0,
  204                             AT_FDCWD);
  205                         if (rpath != NULL)
  206                                 imgp->args->fname_buf =
  207                                     imgp->interpreter_name = rpath;
  208                 }
  209         }
  210         return (error);
  211 }
  212 
  213 int
  214 linux_common_execve(struct thread *td, struct image_args *eargs)
  215 {
  216         struct linux_pemuldata *pem;
  217         struct epoll_emuldata *emd;
  218         struct vmspace *oldvmspace;
  219         struct linux_emuldata *em;
  220         struct proc *p;
  221         int error;
  222 
  223         p = td->td_proc;
  224 
  225         error = pre_execve(td, &oldvmspace);
  226         if (error != 0)
  227                 return (error);
  228 
  229         error = kern_execve(td, eargs, NULL, oldvmspace);
  230         post_execve(td, error, oldvmspace);
  231         if (error != 0)
  232                 return (error);
  233 
  234         /*
  235          * In a case of transition from Linux binary execing to
  236          * FreeBSD binary we destroy Linux emuldata thread & proc entries.
  237          */
  238         if (SV_CURPROC_ABI() != SV_ABI_LINUX) {
  239                 PROC_LOCK(p);
  240                 em = em_find(td);
  241                 KASSERT(em != NULL, ("proc_exec: thread emuldata not found.\n"));
  242                 td->td_emuldata = NULL;
  243 
  244                 pem = pem_find(p);
  245                 KASSERT(pem != NULL, ("proc_exec: proc pemuldata not found.\n"));
  246                 p->p_emuldata = NULL;
  247                 PROC_UNLOCK(p);
  248 
  249                 if (pem->epoll != NULL) {
  250                         emd = pem->epoll;
  251                         pem->epoll = NULL;
  252                         free(emd, M_EPOLL);
  253                 }
  254 
  255                 free(em, M_TEMP);
  256                 free(pem, M_LINUX);
  257         }
  258         return (0);
  259 }
  260 
  261 void
  262 linux_proc_exec(void *arg __unused, struct proc *p, struct image_params *imgp)
  263 {
  264         struct thread *td;
  265         struct thread *othertd;
  266 #if defined(__amd64__)
  267         struct linux_pemuldata *pem;
  268 #endif
  269 
  270         td = curthread;
  271 
  272         /*
  273          * In a case of execing to Linux binary we create Linux
  274          * emuldata thread entry.
  275          */
  276         if (__predict_false((imgp->sysent->sv_flags & SV_ABI_MASK) ==
  277             SV_ABI_LINUX)) {
  278                 if (SV_PROC_ABI(p) == SV_ABI_LINUX) {
  279                         /*
  280                          * Process already was under Linuxolator
  281                          * before exec.  Update emuldata to reflect
  282                          * single-threaded cleaned state after exec.
  283                          */
  284                         linux_proc_init(td, NULL, 0);
  285                 } else {
  286                         /*
  287                          * We are switching the process to Linux emulator.
  288                          */
  289                         linux_proc_init(td, td, 0);
  290 
  291                         /*
  292                          * Create a transient td_emuldata for all suspended
  293                          * threads, so that p->p_sysent->sv_thread_detach() ==
  294                          * linux_thread_detach() can find expected but unused
  295                          * emuldata.
  296                          */
  297                         FOREACH_THREAD_IN_PROC(td->td_proc, othertd) {
  298                                 if (othertd != td) {
  299                                         linux_proc_init(td, othertd,
  300                                             LINUX_CLONE_THREAD);
  301                                 }
  302                         }
  303                 }
  304 #if defined(__amd64__)
  305                 /*
  306                  * An IA32 executable which has executable stack will have the
  307                  * READ_IMPLIES_EXEC personality flag set automatically.
  308                  */
  309                 if (SV_PROC_FLAG(td->td_proc, SV_ILP32) &&
  310                     imgp->stack_prot & VM_PROT_EXECUTE) {
  311                         pem = pem_find(p);
  312                         pem->persona |= LINUX_READ_IMPLIES_EXEC;
  313                 }
  314 #endif
  315         }
  316 }
  317 
  318 void
  319 linux_thread_dtor(void *arg __unused, struct thread *td)
  320 {
  321         struct linux_emuldata *em;
  322 
  323         em = em_find(td);
  324         if (em == NULL)
  325                 return;
  326         td->td_emuldata = NULL;
  327 
  328         LINUX_CTR1(thread_dtor, "thread(%d)", em->em_tid);
  329 
  330         free(em, M_TEMP);
  331 }
  332 
  333 void
  334 linux_schedtail(struct thread *td)
  335 {
  336         struct linux_emuldata *em;
  337         struct proc *p;
  338         int error = 0;
  339         int *child_set_tid;
  340 
  341         p = td->td_proc;
  342 
  343         em = em_find(td);
  344         KASSERT(em != NULL, ("linux_schedtail: thread emuldata not found.\n"));
  345         child_set_tid = em->child_set_tid;
  346 
  347         if (child_set_tid != NULL) {
  348                 error = copyout(&em->em_tid, child_set_tid,
  349                     sizeof(em->em_tid));
  350                 LINUX_CTR4(schedtail, "thread(%d) %p stored %d error %d",
  351                     td->td_tid, child_set_tid, em->em_tid, error);
  352         } else
  353                 LINUX_CTR1(schedtail, "thread(%d)", em->em_tid);
  354 }
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FreeBSD/Linux Kernel Cross Reference sys/compat/linux/linux_emul.c

FreeBSD/Linux Kernel Cross Reference
sys/compat/linux/linux_emul.c
