mm: fix exit_mmap BUG() on a.out binary exit
[safe/jmp/linux-2.6] / fs / binfmt_aout.c
1 /*
2  *  linux/fs/binfmt_aout.c
3  *
4  *  Copyright (C) 1991, 1992, 1996  Linus Torvalds
5  */
6
7 #include <linux/module.h>
8
9 #include <linux/time.h>
10 #include <linux/kernel.h>
11 #include <linux/mm.h>
12 #include <linux/mman.h>
13 #include <linux/a.out.h>
14 #include <linux/errno.h>
15 #include <linux/signal.h>
16 #include <linux/string.h>
17 #include <linux/fs.h>
18 #include <linux/file.h>
19 #include <linux/stat.h>
20 #include <linux/fcntl.h>
21 #include <linux/ptrace.h>
22 #include <linux/user.h>
23 #include <linux/slab.h>
24 #include <linux/binfmts.h>
25 #include <linux/personality.h>
26 #include <linux/init.h>
27
28 #include <asm/system.h>
29 #include <asm/uaccess.h>
30 #include <asm/cacheflush.h>
31
32 static int load_aout_binary(struct linux_binprm *, struct pt_regs * regs);
33 static int load_aout_library(struct file*);
34 static int aout_core_dump(long signr, struct pt_regs *regs, struct file *file, unsigned long limit);
35
36 static struct linux_binfmt aout_format = {
37         .module         = THIS_MODULE,
38         .load_binary    = load_aout_binary,
39         .load_shlib     = load_aout_library,
40         .core_dump      = aout_core_dump,
41         .min_coredump   = PAGE_SIZE
42 };
43
44 #define BAD_ADDR(x)     ((unsigned long)(x) >= TASK_SIZE)
45
46 static int set_brk(unsigned long start, unsigned long end)
47 {
48         start = PAGE_ALIGN(start);
49         end = PAGE_ALIGN(end);
50         if (end > start) {
51                 unsigned long addr;
52                 down_write(&current->mm->mmap_sem);
53                 addr = do_brk(start, end - start);
54                 up_write(&current->mm->mmap_sem);
55                 if (BAD_ADDR(addr))
56                         return addr;
57         }
58         return 0;
59 }
60
61 /*
62  * These are the only things you should do on a core-file: use only these
63  * macros to write out all the necessary info.
64  */
65
66 static int dump_write(struct file *file, const void *addr, int nr)
67 {
68         return file->f_op->write(file, addr, nr, &file->f_pos) == nr;
69 }
70
71 #define DUMP_WRITE(addr, nr)    \
72         if (!dump_write(file, (void *)(addr), (nr))) \
73                 goto end_coredump;
74
75 #define DUMP_SEEK(offset) \
76 if (file->f_op->llseek) { \
77         if (file->f_op->llseek(file,(offset),0) != (offset)) \
78                 goto end_coredump; \
79 } else file->f_pos = (offset)
80
81 /*
82  * Routine writes a core dump image in the current directory.
83  * Currently only a stub-function.
84  *
85  * Note that setuid/setgid files won't make a core-dump if the uid/gid
86  * changed due to the set[u|g]id. It's enforced by the "current->mm->dumpable"
87  * field, which also makes sure the core-dumps won't be recursive if the
88  * dumping of the process results in another error..
89  */
90
91 static int aout_core_dump(long signr, struct pt_regs *regs, struct file *file, unsigned long limit)
92 {
93         mm_segment_t fs;
94         int has_dumped = 0;
95         unsigned long dump_start, dump_size;
96         struct user dump;
97 #if defined(__alpha__)
98 #       define START_DATA(u)    (u.start_data)
99 #elif defined(__arm__)
100 #       define START_DATA(u)    ((u.u_tsize << PAGE_SHIFT) + u.start_code)
101 #elif defined(__sparc__)
102 #       define START_DATA(u)    (u.u_tsize)
103 #elif defined(__i386__) || defined(__mc68000__) || defined(__arch_um__)
104 #       define START_DATA(u)    (u.u_tsize << PAGE_SHIFT)
105 #endif
106 #ifdef __sparc__
107 #       define START_STACK(u)   ((regs->u_regs[UREG_FP]) & ~(PAGE_SIZE - 1))
108 #else
109 #       define START_STACK(u)   (u.start_stack)
110 #endif
111
112         fs = get_fs();
113         set_fs(KERNEL_DS);
114         has_dumped = 1;
115         current->flags |= PF_DUMPCORE;
116         strncpy(dump.u_comm, current->comm, sizeof(dump.u_comm));
117 #ifndef __sparc__
118         dump.u_ar0 = (void *)(((unsigned long)(&dump.regs)) - ((unsigned long)(&dump)));
119 #endif
120         dump.signal = signr;
121         dump_thread(regs, &dump);
122
123 /* If the size of the dump file exceeds the rlimit, then see what would happen
124    if we wrote the stack, but not the data area.  */
125 #ifdef __sparc__
126         if ((dump.u_dsize + dump.u_ssize) > limit)
127                 dump.u_dsize = 0;
128 #else
129         if ((dump.u_dsize + dump.u_ssize+1) * PAGE_SIZE > limit)
130                 dump.u_dsize = 0;
131 #endif
132
133 /* Make sure we have enough room to write the stack and data areas. */
134 #ifdef __sparc__
135         if (dump.u_ssize > limit)
136                 dump.u_ssize = 0;
137 #else
138         if ((dump.u_ssize + 1) * PAGE_SIZE > limit)
139                 dump.u_ssize = 0;
140 #endif
141
142 /* make sure we actually have a data and stack area to dump */
143         set_fs(USER_DS);
144 #ifdef __sparc__
145         if (!access_ok(VERIFY_READ, (void __user *)START_DATA(dump), dump.u_dsize))
146                 dump.u_dsize = 0;
147         if (!access_ok(VERIFY_READ, (void __user *)START_STACK(dump), dump.u_ssize))
148                 dump.u_ssize = 0;
149 #else
150         if (!access_ok(VERIFY_READ, (void __user *)START_DATA(dump), dump.u_dsize << PAGE_SHIFT))
151                 dump.u_dsize = 0;
152         if (!access_ok(VERIFY_READ, (void __user *)START_STACK(dump), dump.u_ssize << PAGE_SHIFT))
153                 dump.u_ssize = 0;
154 #endif
155
156         set_fs(KERNEL_DS);
157 /* struct user */
158         DUMP_WRITE(&dump,sizeof(dump));
159 /* Now dump all of the user data.  Include malloced stuff as well */
160 #ifndef __sparc__
161         DUMP_SEEK(PAGE_SIZE);
162 #endif
163 /* now we start writing out the user space info */
164         set_fs(USER_DS);
165 /* Dump the data area */
166         if (dump.u_dsize != 0) {
167                 dump_start = START_DATA(dump);
168 #ifdef __sparc__
169                 dump_size = dump.u_dsize;
170 #else
171                 dump_size = dump.u_dsize << PAGE_SHIFT;
172 #endif
173                 DUMP_WRITE(dump_start,dump_size);
174         }
175 /* Now prepare to dump the stack area */
176         if (dump.u_ssize != 0) {
177                 dump_start = START_STACK(dump);
178 #ifdef __sparc__
179                 dump_size = dump.u_ssize;
180 #else
181                 dump_size = dump.u_ssize << PAGE_SHIFT;
182 #endif
183                 DUMP_WRITE(dump_start,dump_size);
184         }
185 /* Finally dump the task struct.  Not be used by gdb, but could be useful */
186         set_fs(KERNEL_DS);
187         DUMP_WRITE(current,sizeof(*current));
188 end_coredump:
189         set_fs(fs);
190         return has_dumped;
191 }
192
193 /*
194  * create_aout_tables() parses the env- and arg-strings in new user
195  * memory and creates the pointer tables from them, and puts their
196  * addresses on the "stack", returning the new stack pointer value.
197  */
198 static unsigned long __user *create_aout_tables(char __user *p, struct linux_binprm * bprm)
199 {
200         char __user * __user *argv;
201         char __user * __user *envp;
202         unsigned long __user *sp;
203         int argc = bprm->argc;
204         int envc = bprm->envc;
205
206         sp = (void __user *)((-(unsigned long)sizeof(char *)) & (unsigned long) p);
207 #ifdef __sparc__
208         /* This imposes the proper stack alignment for a new process. */
209         sp = (void __user *) (((unsigned long) sp) & ~7);
210         if ((envc+argc+3)&1) --sp;
211 #endif
212 #ifdef __alpha__
213 /* whee.. test-programs are so much fun. */
214         put_user(0, --sp);
215         put_user(0, --sp);
216         if (bprm->loader) {
217                 put_user(0, --sp);
218                 put_user(0x3eb, --sp);
219                 put_user(bprm->loader, --sp);
220                 put_user(0x3ea, --sp);
221         }
222         put_user(bprm->exec, --sp);
223         put_user(0x3e9, --sp);
224 #endif
225         sp -= envc+1;
226         envp = (char __user * __user *) sp;
227         sp -= argc+1;
228         argv = (char __user * __user *) sp;
229 #if defined(__i386__) || defined(__mc68000__) || defined(__arm__) || defined(__arch_um__)
230         put_user((unsigned long) envp,--sp);
231         put_user((unsigned long) argv,--sp);
232 #endif
233         put_user(argc,--sp);
234         current->mm->arg_start = (unsigned long) p;
235         while (argc-->0) {
236                 char c;
237                 put_user(p,argv++);
238                 do {
239                         get_user(c,p++);
240                 } while (c);
241         }
242         put_user(NULL,argv);
243         current->mm->arg_end = current->mm->env_start = (unsigned long) p;
244         while (envc-->0) {
245                 char c;
246                 put_user(p,envp++);
247                 do {
248                         get_user(c,p++);
249                 } while (c);
250         }
251         put_user(NULL,envp);
252         current->mm->env_end = (unsigned long) p;
253         return sp;
254 }
255
256 /*
257  * These are the functions used to load a.out style executables and shared
258  * libraries.  There is no binary dependent code anywhere else.
259  */
260
261 static int load_aout_binary(struct linux_binprm * bprm, struct pt_regs * regs)
262 {
263         struct exec ex;
264         unsigned long error;
265         unsigned long fd_offset;
266         unsigned long rlim;
267         int retval;
268
269         ex = *((struct exec *) bprm->buf);              /* exec-header */
270         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
271              N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
272             N_TRSIZE(ex) || N_DRSIZE(ex) ||
273             i_size_read(bprm->file->f_path.dentry->d_inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
274                 return -ENOEXEC;
275         }
276
277         /*
278          * Requires a mmap handler. This prevents people from using a.out
279          * as part of an exploit attack against /proc-related vulnerabilities.
280          */
281         if (!bprm->file->f_op || !bprm->file->f_op->mmap)
282                 return -ENOEXEC;
283
284         fd_offset = N_TXTOFF(ex);
285
286         /* Check initial limits. This avoids letting people circumvent
287          * size limits imposed on them by creating programs with large
288          * arrays in the data or bss.
289          */
290         rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
291         if (rlim >= RLIM_INFINITY)
292                 rlim = ~0;
293         if (ex.a_data + ex.a_bss > rlim)
294                 return -ENOMEM;
295
296         /* Flush all traces of the currently running executable */
297         retval = flush_old_exec(bprm);
298         if (retval)
299                 return retval;
300
301         /* OK, This is the point of no return */
302 #if defined(__alpha__)
303         SET_AOUT_PERSONALITY(bprm, ex);
304 #elif defined(__sparc__)
305         set_personality(PER_SUNOS);
306 #if !defined(__sparc_v9__)
307         memcpy(&current->thread.core_exec, &ex, sizeof(struct exec));
308 #endif
309 #else
310         set_personality(PER_LINUX);
311 #endif
312
313         current->mm->end_code = ex.a_text +
314                 (current->mm->start_code = N_TXTADDR(ex));
315         current->mm->end_data = ex.a_data +
316                 (current->mm->start_data = N_DATADDR(ex));
317         current->mm->brk = ex.a_bss +
318                 (current->mm->start_brk = N_BSSADDR(ex));
319         current->mm->free_area_cache = current->mm->mmap_base;
320         current->mm->cached_hole_size = 0;
321
322         compute_creds(bprm);
323         current->flags &= ~PF_FORKNOEXEC;
324 #ifdef __sparc__
325         if (N_MAGIC(ex) == NMAGIC) {
326                 loff_t pos = fd_offset;
327                 /* Fuck me plenty... */
328                 /* <AOL></AOL> */
329                 down_write(&current->mm->mmap_sem);     
330                 error = do_brk(N_TXTADDR(ex), ex.a_text);
331                 up_write(&current->mm->mmap_sem);
332                 bprm->file->f_op->read(bprm->file, (char *) N_TXTADDR(ex),
333                           ex.a_text, &pos);
334                 down_write(&current->mm->mmap_sem);
335                 error = do_brk(N_DATADDR(ex), ex.a_data);
336                 up_write(&current->mm->mmap_sem);
337                 bprm->file->f_op->read(bprm->file, (char *) N_DATADDR(ex),
338                           ex.a_data, &pos);
339                 goto beyond_if;
340         }
341 #endif
342
343         if (N_MAGIC(ex) == OMAGIC) {
344                 unsigned long text_addr, map_size;
345                 loff_t pos;
346
347                 text_addr = N_TXTADDR(ex);
348
349 #if defined(__alpha__) || defined(__sparc__)
350                 pos = fd_offset;
351                 map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
352 #else
353                 pos = 32;
354                 map_size = ex.a_text+ex.a_data;
355 #endif
356                 down_write(&current->mm->mmap_sem);
357                 error = do_brk(text_addr & PAGE_MASK, map_size);
358                 up_write(&current->mm->mmap_sem);
359                 if (error != (text_addr & PAGE_MASK)) {
360                         send_sig(SIGKILL, current, 0);
361                         return error;
362                 }
363
364                 error = bprm->file->f_op->read(bprm->file,
365                           (char __user *)text_addr,
366                           ex.a_text+ex.a_data, &pos);
367                 if ((signed long)error < 0) {
368                         send_sig(SIGKILL, current, 0);
369                         return error;
370                 }
371                          
372                 flush_icache_range(text_addr, text_addr+ex.a_text+ex.a_data);
373         } else {
374                 static unsigned long error_time, error_time2;
375                 if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
376                     (N_MAGIC(ex) != NMAGIC) && (jiffies-error_time2) > 5*HZ)
377                 {
378                         printk(KERN_NOTICE "executable not page aligned\n");
379                         error_time2 = jiffies;
380                 }
381
382                 if ((fd_offset & ~PAGE_MASK) != 0 &&
383                     (jiffies-error_time) > 5*HZ)
384                 {
385                         printk(KERN_WARNING 
386                                "fd_offset is not page aligned. Please convert program: %s\n",
387                                bprm->file->f_path.dentry->d_name.name);
388                         error_time = jiffies;
389                 }
390
391                 if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
392                         loff_t pos = fd_offset;
393                         down_write(&current->mm->mmap_sem);
394                         do_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
395                         up_write(&current->mm->mmap_sem);
396                         bprm->file->f_op->read(bprm->file,
397                                         (char __user *)N_TXTADDR(ex),
398                                         ex.a_text+ex.a_data, &pos);
399                         flush_icache_range((unsigned long) N_TXTADDR(ex),
400                                            (unsigned long) N_TXTADDR(ex) +
401                                            ex.a_text+ex.a_data);
402                         goto beyond_if;
403                 }
404
405                 down_write(&current->mm->mmap_sem);
406                 error = do_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
407                         PROT_READ | PROT_EXEC,
408                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
409                         fd_offset);
410                 up_write(&current->mm->mmap_sem);
411
412                 if (error != N_TXTADDR(ex)) {
413                         send_sig(SIGKILL, current, 0);
414                         return error;
415                 }
416
417                 down_write(&current->mm->mmap_sem);
418                 error = do_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
419                                 PROT_READ | PROT_WRITE | PROT_EXEC,
420                                 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
421                                 fd_offset + ex.a_text);
422                 up_write(&current->mm->mmap_sem);
423                 if (error != N_DATADDR(ex)) {
424                         send_sig(SIGKILL, current, 0);
425                         return error;
426                 }
427         }
428 beyond_if:
429         set_binfmt(&aout_format);
430
431         retval = set_brk(current->mm->start_brk, current->mm->brk);
432         if (retval < 0) {
433                 send_sig(SIGKILL, current, 0);
434                 return retval;
435         }
436
437         retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
438         if (retval < 0) { 
439                 /* Someone check-me: is this error path enough? */ 
440                 send_sig(SIGKILL, current, 0); 
441                 return retval;
442         }
443
444         current->mm->start_stack =
445                 (unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
446 #ifdef __alpha__
447         regs->gp = ex.a_gpvalue;
448 #endif
449         start_thread(regs, ex.a_entry, current->mm->start_stack);
450         if (unlikely(current->ptrace & PT_PTRACED)) {
451                 if (current->ptrace & PT_TRACE_EXEC)
452                         ptrace_notify ((PTRACE_EVENT_EXEC << 8) | SIGTRAP);
453                 else
454                         send_sig(SIGTRAP, current, 0);
455         }
456         return 0;
457 }
458
459 static int load_aout_library(struct file *file)
460 {
461         struct inode * inode;
462         unsigned long bss, start_addr, len;
463         unsigned long error;
464         int retval;
465         struct exec ex;
466
467         inode = file->f_path.dentry->d_inode;
468
469         retval = -ENOEXEC;
470         error = kernel_read(file, 0, (char *) &ex, sizeof(ex));
471         if (error != sizeof(ex))
472                 goto out;
473
474         /* We come in here for the regular a.out style of shared libraries */
475         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
476             N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
477             i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
478                 goto out;
479         }
480
481         /*
482          * Requires a mmap handler. This prevents people from using a.out
483          * as part of an exploit attack against /proc-related vulnerabilities.
484          */
485         if (!file->f_op || !file->f_op->mmap)
486                 goto out;
487
488         if (N_FLAGS(ex))
489                 goto out;
490
491         /* For  QMAGIC, the starting address is 0x20 into the page.  We mask
492            this off to get the starting address for the page */
493
494         start_addr =  ex.a_entry & 0xfffff000;
495
496         if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
497                 static unsigned long error_time;
498                 loff_t pos = N_TXTOFF(ex);
499
500                 if ((jiffies-error_time) > 5*HZ)
501                 {
502                         printk(KERN_WARNING 
503                                "N_TXTOFF is not page aligned. Please convert library: %s\n",
504                                file->f_path.dentry->d_name.name);
505                         error_time = jiffies;
506                 }
507                 down_write(&current->mm->mmap_sem);
508                 do_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
509                 up_write(&current->mm->mmap_sem);
510                 
511                 file->f_op->read(file, (char __user *)start_addr,
512                         ex.a_text + ex.a_data, &pos);
513                 flush_icache_range((unsigned long) start_addr,
514                                    (unsigned long) start_addr + ex.a_text + ex.a_data);
515
516                 retval = 0;
517                 goto out;
518         }
519         /* Now use mmap to map the library into memory. */
520         down_write(&current->mm->mmap_sem);
521         error = do_mmap(file, start_addr, ex.a_text + ex.a_data,
522                         PROT_READ | PROT_WRITE | PROT_EXEC,
523                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
524                         N_TXTOFF(ex));
525         up_write(&current->mm->mmap_sem);
526         retval = error;
527         if (error != start_addr)
528                 goto out;
529
530         len = PAGE_ALIGN(ex.a_text + ex.a_data);
531         bss = ex.a_text + ex.a_data + ex.a_bss;
532         if (bss > len) {
533                 down_write(&current->mm->mmap_sem);
534                 error = do_brk(start_addr + len, bss - len);
535                 up_write(&current->mm->mmap_sem);
536                 retval = error;
537                 if (error != start_addr + len)
538                         goto out;
539         }
540         retval = 0;
541 out:
542         return retval;
543 }
544
545 static int __init init_aout_binfmt(void)
546 {
547         return register_binfmt(&aout_format);
548 }
549
550 static void __exit exit_aout_binfmt(void)
551 {
552         unregister_binfmt(&aout_format);
553 }
554
555 core_initcall(init_aout_binfmt);
556 module_exit(exit_aout_binfmt);
557 MODULE_LICENSE("GPL");