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