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Linux/arch/x86/ia32/ia32_aout.c

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  1 /*
  2  *  a.out loader for x86-64
  3  *
  4  *  Copyright (C) 1991, 1992, 1996  Linus Torvalds
  5  *  Hacked together by Andi Kleen
  6  */
  7 
  8 #include <linux/module.h>
  9 
 10 #include <linux/time.h>
 11 #include <linux/kernel.h>
 12 #include <linux/mm.h>
 13 #include <linux/mman.h>
 14 #include <linux/a.out.h>
 15 #include <linux/errno.h>
 16 #include <linux/signal.h>
 17 #include <linux/string.h>
 18 #include <linux/fs.h>
 19 #include <linux/file.h>
 20 #include <linux/stat.h>
 21 #include <linux/fcntl.h>
 22 #include <linux/ptrace.h>
 23 #include <linux/user.h>
 24 #include <linux/binfmts.h>
 25 #include <linux/personality.h>
 26 #include <linux/init.h>
 27 #include <linux/jiffies.h>
 28 #include <linux/perf_event.h>
 29 #include <linux/sched/task_stack.h>
 30 
 31 #include <linux/uaccess.h>
 32 #include <asm/pgalloc.h>
 33 #include <asm/cacheflush.h>
 34 #include <asm/user32.h>
 35 #include <asm/ia32.h>
 36 
 37 #undef WARN_OLD
 38 
 39 static int load_aout_binary(struct linux_binprm *);
 40 static int load_aout_library(struct file *);
 41 
 42 #ifdef CONFIG_COREDUMP
 43 static int aout_core_dump(struct coredump_params *);
 44 
 45 static unsigned long get_dr(int n)
 46 {
 47         struct perf_event *bp = current->thread.ptrace_bps[n];
 48         return bp ? bp->hw.info.address : 0;
 49 }
 50 
 51 /*
 52  * fill in the user structure for a core dump..
 53  */
 54 static void dump_thread32(struct pt_regs *regs, struct user32 *dump)
 55 {
 56         u32 fs, gs;
 57         memset(dump, 0, sizeof(*dump));
 58 
 59 /* changed the size calculations - should hopefully work better. lbt */
 60         dump->magic = CMAGIC;
 61         dump->start_code = 0;
 62         dump->start_stack = regs->sp & ~(PAGE_SIZE - 1);
 63         dump->u_tsize = ((unsigned long) current->mm->end_code) >> PAGE_SHIFT;
 64         dump->u_dsize = ((unsigned long)
 65                          (current->mm->brk + (PAGE_SIZE-1))) >> PAGE_SHIFT;
 66         dump->u_dsize -= dump->u_tsize;
 67         dump->u_debugreg[0] = get_dr(0);
 68         dump->u_debugreg[1] = get_dr(1);
 69         dump->u_debugreg[2] = get_dr(2);
 70         dump->u_debugreg[3] = get_dr(3);
 71         dump->u_debugreg[6] = current->thread.debugreg6;
 72         dump->u_debugreg[7] = current->thread.ptrace_dr7;
 73 
 74         if (dump->start_stack < 0xc0000000) {
 75                 unsigned long tmp;
 76 
 77                 tmp = (unsigned long) (0xc0000000 - dump->start_stack);
 78                 dump->u_ssize = tmp >> PAGE_SHIFT;
 79         }
 80 
 81         dump->regs.ebx = regs->bx;
 82         dump->regs.ecx = regs->cx;
 83         dump->regs.edx = regs->dx;
 84         dump->regs.esi = regs->si;
 85         dump->regs.edi = regs->di;
 86         dump->regs.ebp = regs->bp;
 87         dump->regs.eax = regs->ax;
 88         dump->regs.ds = current->thread.ds;
 89         dump->regs.es = current->thread.es;
 90         savesegment(fs, fs);
 91         dump->regs.fs = fs;
 92         savesegment(gs, gs);
 93         dump->regs.gs = gs;
 94         dump->regs.orig_eax = regs->orig_ax;
 95         dump->regs.eip = regs->ip;
 96         dump->regs.cs = regs->cs;
 97         dump->regs.eflags = regs->flags;
 98         dump->regs.esp = regs->sp;
 99         dump->regs.ss = regs->ss;
100 
101 #if 1 /* FIXME */
102         dump->u_fpvalid = 0;
103 #else
104         dump->u_fpvalid = dump_fpu(regs, &dump->i387);
105 #endif
106 }
107 
108 #endif
109 
110 static struct linux_binfmt aout_format = {
111         .module         = THIS_MODULE,
112         .load_binary    = load_aout_binary,
113         .load_shlib     = load_aout_library,
114 #ifdef CONFIG_COREDUMP
115         .core_dump      = aout_core_dump,
116 #endif
117         .min_coredump   = PAGE_SIZE
118 };
119 
120 static int set_brk(unsigned long start, unsigned long end)
121 {
122         start = PAGE_ALIGN(start);
123         end = PAGE_ALIGN(end);
124         if (end <= start)
125                 return 0;
126         return vm_brk(start, end - start);
127 }
128 
129 #ifdef CONFIG_COREDUMP
130 /*
131  * These are the only things you should do on a core-file: use only these
132  * macros to write out all the necessary info.
133  */
134 
135 #include <linux/coredump.h>
136 
137 #define START_DATA(u)   (u.u_tsize << PAGE_SHIFT)
138 #define START_STACK(u)  (u.start_stack)
139 
140 /*
141  * Routine writes a core dump image in the current directory.
142  * Currently only a stub-function.
143  *
144  * Note that setuid/setgid files won't make a core-dump if the uid/gid
145  * changed due to the set[u|g]id. It's enforced by the "current->mm->dumpable"
146  * field, which also makes sure the core-dumps won't be recursive if the
147  * dumping of the process results in another error..
148  */
149 
150 static int aout_core_dump(struct coredump_params *cprm)
151 {
152         mm_segment_t fs;
153         int has_dumped = 0;
154         unsigned long dump_start, dump_size;
155         struct user32 dump;
156 
157         fs = get_fs();
158         set_fs(KERNEL_DS);
159         has_dumped = 1;
160         strncpy(dump.u_comm, current->comm, sizeof(current->comm));
161         dump.u_ar0 = offsetof(struct user32, regs);
162         dump.signal = cprm->siginfo->si_signo;
163         dump_thread32(cprm->regs, &dump);
164 
165         /*
166          * If the size of the dump file exceeds the rlimit, then see
167          * what would happen if we wrote the stack, but not the data
168          * area.
169          */
170         if ((dump.u_dsize + dump.u_ssize + 1) * PAGE_SIZE > cprm->limit)
171                 dump.u_dsize = 0;
172 
173         /* Make sure we have enough room to write the stack and data areas. */
174         if ((dump.u_ssize + 1) * PAGE_SIZE > cprm->limit)
175                 dump.u_ssize = 0;
176 
177         /* make sure we actually have a data and stack area to dump */
178         set_fs(USER_DS);
179         if (!access_ok(VERIFY_READ, (void *) (unsigned long)START_DATA(dump),
180                        dump.u_dsize << PAGE_SHIFT))
181                 dump.u_dsize = 0;
182         if (!access_ok(VERIFY_READ, (void *) (unsigned long)START_STACK(dump),
183                        dump.u_ssize << PAGE_SHIFT))
184                 dump.u_ssize = 0;
185 
186         set_fs(KERNEL_DS);
187         /* struct user */
188         if (!dump_emit(cprm, &dump, sizeof(dump)))
189                 goto end_coredump;
190         /* Now dump all of the user data.  Include malloced stuff as well */
191         if (!dump_skip(cprm, PAGE_SIZE - sizeof(dump)))
192                 goto end_coredump;
193         /* now we start writing out the user space info */
194         set_fs(USER_DS);
195         /* Dump the data area */
196         if (dump.u_dsize != 0) {
197                 dump_start = START_DATA(dump);
198                 dump_size = dump.u_dsize << PAGE_SHIFT;
199                 if (!dump_emit(cprm, (void *)dump_start, dump_size))
200                         goto end_coredump;
201         }
202         /* Now prepare to dump the stack area */
203         if (dump.u_ssize != 0) {
204                 dump_start = START_STACK(dump);
205                 dump_size = dump.u_ssize << PAGE_SHIFT;
206                 if (!dump_emit(cprm, (void *)dump_start, dump_size))
207                         goto end_coredump;
208         }
209 end_coredump:
210         set_fs(fs);
211         return has_dumped;
212 }
213 #endif
214 
215 /*
216  * create_aout_tables() parses the env- and arg-strings in new user
217  * memory and creates the pointer tables from them, and puts their
218  * addresses on the "stack", returning the new stack pointer value.
219  */
220 static u32 __user *create_aout_tables(char __user *p, struct linux_binprm *bprm)
221 {
222         u32 __user *argv, *envp, *sp;
223         int argc = bprm->argc, envc = bprm->envc;
224 
225         sp = (u32 __user *) ((-(unsigned long)sizeof(u32)) & (unsigned long) p);
226         sp -= envc+1;
227         envp = sp;
228         sp -= argc+1;
229         argv = sp;
230         put_user((unsigned long) envp, --sp);
231         put_user((unsigned long) argv, --sp);
232         put_user(argc, --sp);
233         current->mm->arg_start = (unsigned long) p;
234         while (argc-- > 0) {
235                 char c;
236 
237                 put_user((u32)(unsigned long)p, argv++);
238                 do {
239                         get_user(c, p++);
240                 } while (c);
241         }
242         put_user(0, argv);
243         current->mm->arg_end = current->mm->env_start = (unsigned long) p;
244         while (envc-- > 0) {
245                 char c;
246 
247                 put_user((u32)(unsigned long)p, envp++);
248                 do {
249                         get_user(c, p++);
250                 } while (c);
251         }
252         put_user(0, envp);
253         current->mm->env_end = (unsigned long) p;
254         return sp;
255 }
256 
257 /*
258  * These are the functions used to load a.out style executables and shared
259  * libraries.  There is no binary dependent code anywhere else.
260  */
261 static int load_aout_binary(struct linux_binprm *bprm)
262 {
263         unsigned long error, fd_offset, rlim;
264         struct pt_regs *regs = current_pt_regs();
265         struct exec ex;
266         int retval;
267 
268         ex = *((struct exec *) bprm->buf);              /* exec-header */
269         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
270              N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
271             N_TRSIZE(ex) || N_DRSIZE(ex) ||
272             i_size_read(file_inode(bprm->file)) <
273             ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
274                 return -ENOEXEC;
275         }
276 
277         fd_offset = N_TXTOFF(ex);
278 
279         /* Check initial limits. This avoids letting people circumvent
280          * size limits imposed on them by creating programs with large
281          * arrays in the data or bss.
282          */
283         rlim = rlimit(RLIMIT_DATA);
284         if (rlim >= RLIM_INFINITY)
285                 rlim = ~0;
286         if (ex.a_data + ex.a_bss > rlim)
287                 return -ENOMEM;
288 
289         /* Flush all traces of the currently running executable */
290         retval = flush_old_exec(bprm);
291         if (retval)
292                 return retval;
293 
294         /* OK, This is the point of no return */
295         set_personality(PER_LINUX);
296         set_personality_ia32(false);
297 
298         setup_new_exec(bprm);
299 
300         regs->cs = __USER32_CS;
301         regs->r8 = regs->r9 = regs->r10 = regs->r11 = regs->r12 =
302                 regs->r13 = regs->r14 = regs->r15 = 0;
303 
304         current->mm->end_code = ex.a_text +
305                 (current->mm->start_code = N_TXTADDR(ex));
306         current->mm->end_data = ex.a_data +
307                 (current->mm->start_data = N_DATADDR(ex));
308         current->mm->brk = ex.a_bss +
309                 (current->mm->start_brk = N_BSSADDR(ex));
310 
311         retval = setup_arg_pages(bprm, IA32_STACK_TOP, EXSTACK_DEFAULT);
312         if (retval < 0)
313                 return retval;
314 
315         install_exec_creds(bprm);
316 
317         if (N_MAGIC(ex) == OMAGIC) {
318                 unsigned long text_addr, map_size;
319 
320                 text_addr = N_TXTADDR(ex);
321                 map_size = ex.a_text+ex.a_data;
322 
323                 error = vm_brk(text_addr & PAGE_MASK, map_size);
324 
325                 if (error)
326                         return error;
327 
328                 error = read_code(bprm->file, text_addr, 32,
329                                   ex.a_text + ex.a_data);
330                 if ((signed long)error < 0)
331                         return error;
332         } else {
333 #ifdef WARN_OLD
334                 static unsigned long error_time, error_time2;
335                 if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
336                     (N_MAGIC(ex) != NMAGIC) &&
337                                 time_after(jiffies, error_time2 + 5*HZ)) {
338                         printk(KERN_NOTICE "executable not page aligned\n");
339                         error_time2 = jiffies;
340                 }
341 
342                 if ((fd_offset & ~PAGE_MASK) != 0 &&
343                             time_after(jiffies, error_time + 5*HZ)) {
344                         printk(KERN_WARNING
345                                "fd_offset is not page aligned. Please convert "
346                                "program: %pD\n",
347                                bprm->file);
348                         error_time = jiffies;
349                 }
350 #endif
351 
352                 if (!bprm->file->f_op->mmap || (fd_offset & ~PAGE_MASK) != 0) {
353                         error = vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
354                         if (error)
355                                 return error;
356 
357                         read_code(bprm->file, N_TXTADDR(ex), fd_offset,
358                                         ex.a_text+ex.a_data);
359                         goto beyond_if;
360                 }
361 
362                 error = vm_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
363                                 PROT_READ | PROT_EXEC,
364                                 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE |
365                                 MAP_EXECUTABLE | MAP_32BIT,
366                                 fd_offset);
367 
368                 if (error != N_TXTADDR(ex))
369                         return error;
370 
371                 error = vm_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
372                                 PROT_READ | PROT_WRITE | PROT_EXEC,
373                                 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE |
374                                 MAP_EXECUTABLE | MAP_32BIT,
375                                 fd_offset + ex.a_text);
376                 if (error != N_DATADDR(ex))
377                         return error;
378         }
379 
380 beyond_if:
381         error = set_brk(current->mm->start_brk, current->mm->brk);
382         if (error)
383                 return error;
384 
385         set_binfmt(&aout_format);
386 
387         current->mm->start_stack =
388                 (unsigned long)create_aout_tables((char __user *)bprm->p, bprm);
389         /* start thread */
390         loadsegment(fs, 0);
391         loadsegment(ds, __USER32_DS);
392         loadsegment(es, __USER32_DS);
393         load_gs_index(0);
394         (regs)->ip = ex.a_entry;
395         (regs)->sp = current->mm->start_stack;
396         (regs)->flags = 0x200;
397         (regs)->cs = __USER32_CS;
398         (regs)->ss = __USER32_DS;
399         regs->r8 = regs->r9 = regs->r10 = regs->r11 =
400         regs->r12 = regs->r13 = regs->r14 = regs->r15 = 0;
401         set_fs(USER_DS);
402         return 0;
403 }
404 
405 static int load_aout_library(struct file *file)
406 {
407         unsigned long bss, start_addr, len, error;
408         int retval;
409         struct exec ex;
410         loff_t pos = 0;
411 
412         retval = -ENOEXEC;
413         error = kernel_read(file, &ex, sizeof(ex), &pos);
414         if (error != sizeof(ex))
415                 goto out;
416 
417         /* We come in here for the regular a.out style of shared libraries */
418         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
419             N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
420             i_size_read(file_inode(file)) <
421             ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
422                 goto out;
423         }
424 
425         if (N_FLAGS(ex))
426                 goto out;
427 
428         /* For  QMAGIC, the starting address is 0x20 into the page.  We mask
429            this off to get the starting address for the page */
430 
431         start_addr =  ex.a_entry & 0xfffff000;
432 
433         if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
434 #ifdef WARN_OLD
435                 static unsigned long error_time;
436                 if (time_after(jiffies, error_time + 5*HZ)) {
437                         printk(KERN_WARNING
438                                "N_TXTOFF is not page aligned. Please convert "
439                                "library: %pD\n",
440                                file);
441                         error_time = jiffies;
442                 }
443 #endif
444                 retval = vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
445                 if (retval)
446                         goto out;
447 
448                 read_code(file, start_addr, N_TXTOFF(ex),
449                           ex.a_text + ex.a_data);
450                 retval = 0;
451                 goto out;
452         }
453         /* Now use mmap to map the library into memory. */
454         error = vm_mmap(file, start_addr, ex.a_text + ex.a_data,
455                         PROT_READ | PROT_WRITE | PROT_EXEC,
456                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_32BIT,
457                         N_TXTOFF(ex));
458         retval = error;
459         if (error != start_addr)
460                 goto out;
461 
462         len = PAGE_ALIGN(ex.a_text + ex.a_data);
463         bss = ex.a_text + ex.a_data + ex.a_bss;
464         if (bss > len) {
465                 retval = vm_brk(start_addr + len, bss - len);
466                 if (retval)
467                         goto out;
468         }
469         retval = 0;
470 out:
471         return retval;
472 }
473 
474 static int __init init_aout_binfmt(void)
475 {
476         register_binfmt(&aout_format);
477         return 0;
478 }
479 
480 static void __exit exit_aout_binfmt(void)
481 {
482         unregister_binfmt(&aout_format);
483 }
484 
485 module_init(init_aout_binfmt);
486 module_exit(exit_aout_binfmt);
487 MODULE_LICENSE("GPL");
488 

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