block: fix bogus gcc warning for uninitialized var usage
[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 #include <asm/a.out-core.h>
32
33 static int load_aout_binary(struct linux_binprm *, struct pt_regs * regs);
34 static int load_aout_library(struct file*);
35 static int aout_core_dump(long signr, struct pt_regs *regs, struct file *file, unsigned long limit);
36
37 static struct linux_binfmt aout_format = {
38         .module         = THIS_MODULE,
39         .load_binary    = load_aout_binary,
40         .load_shlib     = load_aout_library,
41         .core_dump      = aout_core_dump,
42         .min_coredump   = PAGE_SIZE
43 };
44
45 #define BAD_ADDR(x)     ((unsigned long)(x) >= TASK_SIZE)
46
47 static int set_brk(unsigned long start, unsigned long end)
48 {
49         start = PAGE_ALIGN(start);
50         end = PAGE_ALIGN(end);
51         if (end > start) {
52                 unsigned long addr;
53                 down_write(&current->mm->mmap_sem);
54                 addr = do_brk(start, end - start);
55                 up_write(&current->mm->mmap_sem);
56                 if (BAD_ADDR(addr))
57                         return addr;
58         }
59         return 0;
60 }
61
62 /*
63  * These are the only things you should do on a core-file: use only these
64  * macros to write out all the necessary info.
65  */
66
67 static int dump_write(struct file *file, const void *addr, int nr)
68 {
69         return file->f_op->write(file, addr, nr, &file->f_pos) == nr;
70 }
71
72 #define DUMP_WRITE(addr, nr)    \
73         if (!dump_write(file, (void *)(addr), (nr))) \
74                 goto end_coredump;
75
76 #define DUMP_SEEK(offset) \
77 if (file->f_op->llseek) { \
78         if (file->f_op->llseek(file,(offset),0) != (offset)) \
79                 goto end_coredump; \
80 } else file->f_pos = (offset)
81
82 /*
83  * Routine writes a core dump image in the current directory.
84  * Currently only a stub-function.
85  *
86  * Note that setuid/setgid files won't make a core-dump if the uid/gid
87  * changed due to the set[u|g]id. It's enforced by the "current->mm->dumpable"
88  * field, which also makes sure the core-dumps won't be recursive if the
89  * dumping of the process results in another error..
90  */
91
92 static int aout_core_dump(long signr, struct pt_regs *regs, struct file *file, unsigned long limit)
93 {
94         mm_segment_t fs;
95         int has_dumped = 0;
96         unsigned long dump_start, dump_size;
97         struct user dump;
98 #ifdef __alpha__
99 #       define START_DATA(u)    (u.start_data)
100 #else
101 #       define START_DATA(u)    ((u.u_tsize << PAGE_SHIFT) + u.start_code)
102 #endif
103 #       define START_STACK(u)   (u.start_stack)
104
105         fs = get_fs();
106         set_fs(KERNEL_DS);
107         has_dumped = 1;
108         current->flags |= PF_DUMPCORE;
109         strncpy(dump.u_comm, current->comm, sizeof(dump.u_comm));
110         dump.u_ar0 = offsetof(struct user, regs);
111         dump.signal = signr;
112         aout_dump_thread(regs, &dump);
113
114 /* If the size of the dump file exceeds the rlimit, then see what would happen
115    if we wrote the stack, but not the data area.  */
116         if ((dump.u_dsize + dump.u_ssize+1) * PAGE_SIZE > limit)
117                 dump.u_dsize = 0;
118
119 /* Make sure we have enough room to write the stack and data areas. */
120         if ((dump.u_ssize + 1) * PAGE_SIZE > limit)
121                 dump.u_ssize = 0;
122
123 /* make sure we actually have a data and stack area to dump */
124         set_fs(USER_DS);
125         if (!access_ok(VERIFY_READ, (void __user *)START_DATA(dump), dump.u_dsize << PAGE_SHIFT))
126                 dump.u_dsize = 0;
127         if (!access_ok(VERIFY_READ, (void __user *)START_STACK(dump), dump.u_ssize << PAGE_SHIFT))
128                 dump.u_ssize = 0;
129
130         set_fs(KERNEL_DS);
131 /* struct user */
132         DUMP_WRITE(&dump,sizeof(dump));
133 /* Now dump all of the user data.  Include malloced stuff as well */
134         DUMP_SEEK(PAGE_SIZE);
135 /* now we start writing out the user space info */
136         set_fs(USER_DS);
137 /* Dump the data area */
138         if (dump.u_dsize != 0) {
139                 dump_start = START_DATA(dump);
140                 dump_size = dump.u_dsize << PAGE_SHIFT;
141                 DUMP_WRITE(dump_start,dump_size);
142         }
143 /* Now prepare to dump the stack area */
144         if (dump.u_ssize != 0) {
145                 dump_start = START_STACK(dump);
146                 dump_size = dump.u_ssize << PAGE_SHIFT;
147                 DUMP_WRITE(dump_start,dump_size);
148         }
149 /* Finally dump the task struct.  Not be used by gdb, but could be useful */
150         set_fs(KERNEL_DS);
151         DUMP_WRITE(current,sizeof(*current));
152 end_coredump:
153         set_fs(fs);
154         return has_dumped;
155 }
156
157 /*
158  * create_aout_tables() parses the env- and arg-strings in new user
159  * memory and creates the pointer tables from them, and puts their
160  * addresses on the "stack", returning the new stack pointer value.
161  */
162 static unsigned long __user *create_aout_tables(char __user *p, struct linux_binprm * bprm)
163 {
164         char __user * __user *argv;
165         char __user * __user *envp;
166         unsigned long __user *sp;
167         int argc = bprm->argc;
168         int envc = bprm->envc;
169
170         sp = (void __user *)((-(unsigned long)sizeof(char *)) & (unsigned long) p);
171 #ifdef __alpha__
172 /* whee.. test-programs are so much fun. */
173         put_user(0, --sp);
174         put_user(0, --sp);
175         if (bprm->loader) {
176                 put_user(0, --sp);
177                 put_user(1003, --sp);
178                 put_user(bprm->loader, --sp);
179                 put_user(1002, --sp);
180         }
181         put_user(bprm->exec, --sp);
182         put_user(1001, --sp);
183 #endif
184         sp -= envc+1;
185         envp = (char __user * __user *) sp;
186         sp -= argc+1;
187         argv = (char __user * __user *) sp;
188 #ifndef __alpha__
189         put_user((unsigned long) envp,--sp);
190         put_user((unsigned long) argv,--sp);
191 #endif
192         put_user(argc,--sp);
193         current->mm->arg_start = (unsigned long) p;
194         while (argc-->0) {
195                 char c;
196                 put_user(p,argv++);
197                 do {
198                         get_user(c,p++);
199                 } while (c);
200         }
201         put_user(NULL,argv);
202         current->mm->arg_end = current->mm->env_start = (unsigned long) p;
203         while (envc-->0) {
204                 char c;
205                 put_user(p,envp++);
206                 do {
207                         get_user(c,p++);
208                 } while (c);
209         }
210         put_user(NULL,envp);
211         current->mm->env_end = (unsigned long) p;
212         return sp;
213 }
214
215 /*
216  * These are the functions used to load a.out style executables and shared
217  * libraries.  There is no binary dependent code anywhere else.
218  */
219
220 static int load_aout_binary(struct linux_binprm * bprm, struct pt_regs * regs)
221 {
222         struct exec ex;
223         unsigned long error;
224         unsigned long fd_offset;
225         unsigned long rlim;
226         int retval;
227
228         ex = *((struct exec *) bprm->buf);              /* exec-header */
229         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
230              N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
231             N_TRSIZE(ex) || N_DRSIZE(ex) ||
232             i_size_read(bprm->file->f_path.dentry->d_inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
233                 return -ENOEXEC;
234         }
235
236         /*
237          * Requires a mmap handler. This prevents people from using a.out
238          * as part of an exploit attack against /proc-related vulnerabilities.
239          */
240         if (!bprm->file->f_op || !bprm->file->f_op->mmap)
241                 return -ENOEXEC;
242
243         fd_offset = N_TXTOFF(ex);
244
245         /* Check initial limits. This avoids letting people circumvent
246          * size limits imposed on them by creating programs with large
247          * arrays in the data or bss.
248          */
249         rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
250         if (rlim >= RLIM_INFINITY)
251                 rlim = ~0;
252         if (ex.a_data + ex.a_bss > rlim)
253                 return -ENOMEM;
254
255         /* Flush all traces of the currently running executable */
256         retval = flush_old_exec(bprm);
257         if (retval)
258                 return retval;
259
260         /* OK, This is the point of no return */
261 #ifdef __alpha__
262         SET_AOUT_PERSONALITY(bprm, ex);
263 #else
264         set_personality(PER_LINUX);
265 #endif
266
267         current->mm->end_code = ex.a_text +
268                 (current->mm->start_code = N_TXTADDR(ex));
269         current->mm->end_data = ex.a_data +
270                 (current->mm->start_data = N_DATADDR(ex));
271         current->mm->brk = ex.a_bss +
272                 (current->mm->start_brk = N_BSSADDR(ex));
273         current->mm->free_area_cache = current->mm->mmap_base;
274         current->mm->cached_hole_size = 0;
275
276         install_exec_creds(bprm);
277         current->flags &= ~PF_FORKNOEXEC;
278
279         if (N_MAGIC(ex) == OMAGIC) {
280                 unsigned long text_addr, map_size;
281                 loff_t pos;
282
283                 text_addr = N_TXTADDR(ex);
284
285 #ifdef __alpha__
286                 pos = fd_offset;
287                 map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
288 #else
289                 pos = 32;
290                 map_size = ex.a_text+ex.a_data;
291 #endif
292                 down_write(&current->mm->mmap_sem);
293                 error = do_brk(text_addr & PAGE_MASK, map_size);
294                 up_write(&current->mm->mmap_sem);
295                 if (error != (text_addr & PAGE_MASK)) {
296                         send_sig(SIGKILL, current, 0);
297                         return error;
298                 }
299
300                 error = bprm->file->f_op->read(bprm->file,
301                           (char __user *)text_addr,
302                           ex.a_text+ex.a_data, &pos);
303                 if ((signed long)error < 0) {
304                         send_sig(SIGKILL, current, 0);
305                         return error;
306                 }
307                          
308                 flush_icache_range(text_addr, text_addr+ex.a_text+ex.a_data);
309         } else {
310                 if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
311                     (N_MAGIC(ex) != NMAGIC) && printk_ratelimit())
312                 {
313                         printk(KERN_NOTICE "executable not page aligned\n");
314                 }
315
316                 if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit())
317                 {
318                         printk(KERN_WARNING 
319                                "fd_offset is not page aligned. Please convert program: %s\n",
320                                bprm->file->f_path.dentry->d_name.name);
321                 }
322
323                 if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
324                         loff_t pos = fd_offset;
325                         down_write(&current->mm->mmap_sem);
326                         do_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
327                         up_write(&current->mm->mmap_sem);
328                         bprm->file->f_op->read(bprm->file,
329                                         (char __user *)N_TXTADDR(ex),
330                                         ex.a_text+ex.a_data, &pos);
331                         flush_icache_range((unsigned long) N_TXTADDR(ex),
332                                            (unsigned long) N_TXTADDR(ex) +
333                                            ex.a_text+ex.a_data);
334                         goto beyond_if;
335                 }
336
337                 down_write(&current->mm->mmap_sem);
338                 error = do_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
339                         PROT_READ | PROT_EXEC,
340                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
341                         fd_offset);
342                 up_write(&current->mm->mmap_sem);
343
344                 if (error != N_TXTADDR(ex)) {
345                         send_sig(SIGKILL, current, 0);
346                         return error;
347                 }
348
349                 down_write(&current->mm->mmap_sem);
350                 error = do_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
351                                 PROT_READ | PROT_WRITE | PROT_EXEC,
352                                 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
353                                 fd_offset + ex.a_text);
354                 up_write(&current->mm->mmap_sem);
355                 if (error != N_DATADDR(ex)) {
356                         send_sig(SIGKILL, current, 0);
357                         return error;
358                 }
359         }
360 beyond_if:
361         set_binfmt(&aout_format);
362
363         retval = set_brk(current->mm->start_brk, current->mm->brk);
364         if (retval < 0) {
365                 send_sig(SIGKILL, current, 0);
366                 return retval;
367         }
368
369         retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
370         if (retval < 0) { 
371                 /* Someone check-me: is this error path enough? */ 
372                 send_sig(SIGKILL, current, 0); 
373                 return retval;
374         }
375
376         current->mm->start_stack =
377                 (unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
378 #ifdef __alpha__
379         regs->gp = ex.a_gpvalue;
380 #endif
381         start_thread(regs, ex.a_entry, current->mm->start_stack);
382         return 0;
383 }
384
385 static int load_aout_library(struct file *file)
386 {
387         struct inode * inode;
388         unsigned long bss, start_addr, len;
389         unsigned long error;
390         int retval;
391         struct exec ex;
392
393         inode = file->f_path.dentry->d_inode;
394
395         retval = -ENOEXEC;
396         error = kernel_read(file, 0, (char *) &ex, sizeof(ex));
397         if (error != sizeof(ex))
398                 goto out;
399
400         /* We come in here for the regular a.out style of shared libraries */
401         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
402             N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
403             i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
404                 goto out;
405         }
406
407         /*
408          * Requires a mmap handler. This prevents people from using a.out
409          * as part of an exploit attack against /proc-related vulnerabilities.
410          */
411         if (!file->f_op || !file->f_op->mmap)
412                 goto out;
413
414         if (N_FLAGS(ex))
415                 goto out;
416
417         /* For  QMAGIC, the starting address is 0x20 into the page.  We mask
418            this off to get the starting address for the page */
419
420         start_addr =  ex.a_entry & 0xfffff000;
421
422         if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
423                 loff_t pos = N_TXTOFF(ex);
424
425                 if (printk_ratelimit())
426                 {
427                         printk(KERN_WARNING 
428                                "N_TXTOFF is not page aligned. Please convert library: %s\n",
429                                file->f_path.dentry->d_name.name);
430                 }
431                 down_write(&current->mm->mmap_sem);
432                 do_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
433                 up_write(&current->mm->mmap_sem);
434                 
435                 file->f_op->read(file, (char __user *)start_addr,
436                         ex.a_text + ex.a_data, &pos);
437                 flush_icache_range((unsigned long) start_addr,
438                                    (unsigned long) start_addr + ex.a_text + ex.a_data);
439
440                 retval = 0;
441                 goto out;
442         }
443         /* Now use mmap to map the library into memory. */
444         down_write(&current->mm->mmap_sem);
445         error = do_mmap(file, start_addr, ex.a_text + ex.a_data,
446                         PROT_READ | PROT_WRITE | PROT_EXEC,
447                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
448                         N_TXTOFF(ex));
449         up_write(&current->mm->mmap_sem);
450         retval = error;
451         if (error != start_addr)
452                 goto out;
453
454         len = PAGE_ALIGN(ex.a_text + ex.a_data);
455         bss = ex.a_text + ex.a_data + ex.a_bss;
456         if (bss > len) {
457                 down_write(&current->mm->mmap_sem);
458                 error = do_brk(start_addr + len, bss - len);
459                 up_write(&current->mm->mmap_sem);
460                 retval = error;
461                 if (error != start_addr + len)
462                         goto out;
463         }
464         retval = 0;
465 out:
466         return retval;
467 }
468
469 static int __init init_aout_binfmt(void)
470 {
471         return register_binfmt(&aout_format);
472 }
473
474 static void __exit exit_aout_binfmt(void)
475 {
476         unregister_binfmt(&aout_format);
477 }
478
479 core_initcall(init_aout_binfmt);
480 module_exit(exit_aout_binfmt);
481 MODULE_LICENSE("GPL");