Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes...
[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 #include <linux/coredump.h>
28
29 #include <asm/system.h>
30 #include <asm/uaccess.h>
31 #include <asm/cacheflush.h>
32 #include <asm/a.out-core.h>
33
34 static int load_aout_binary(struct linux_binprm *, struct pt_regs * regs);
35 static int load_aout_library(struct file*);
36 static int aout_core_dump(struct coredump_params *cprm);
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  * Routine writes a core dump image in the current directory.
65  * Currently only a stub-function.
66  *
67  * Note that setuid/setgid files won't make a core-dump if the uid/gid
68  * changed due to the set[u|g]id. It's enforced by the "current->mm->dumpable"
69  * field, which also makes sure the core-dumps won't be recursive if the
70  * dumping of the process results in another error..
71  */
72
73 static int aout_core_dump(struct coredump_params *cprm)
74 {
75         struct file *file = cprm->file;
76         mm_segment_t fs;
77         int has_dumped = 0;
78         void __user *dump_start;
79         int dump_size;
80         struct user dump;
81 #ifdef __alpha__
82 #       define START_DATA(u)    ((void __user *)u.start_data)
83 #else
84 #       define START_DATA(u)    ((void __user *)((u.u_tsize << PAGE_SHIFT) + \
85                                  u.start_code))
86 #endif
87 #       define START_STACK(u)   ((void __user *)u.start_stack)
88
89         fs = get_fs();
90         set_fs(KERNEL_DS);
91         has_dumped = 1;
92         current->flags |= PF_DUMPCORE;
93         strncpy(dump.u_comm, current->comm, sizeof(dump.u_comm));
94         dump.u_ar0 = offsetof(struct user, regs);
95         dump.signal = cprm->signr;
96         aout_dump_thread(cprm->regs, &dump);
97
98 /* If the size of the dump file exceeds the rlimit, then see what would happen
99    if we wrote the stack, but not the data area.  */
100         if ((dump.u_dsize + dump.u_ssize+1) * PAGE_SIZE > cprm->limit)
101                 dump.u_dsize = 0;
102
103 /* Make sure we have enough room to write the stack and data areas. */
104         if ((dump.u_ssize + 1) * PAGE_SIZE > cprm->limit)
105                 dump.u_ssize = 0;
106
107 /* make sure we actually have a data and stack area to dump */
108         set_fs(USER_DS);
109         if (!access_ok(VERIFY_READ, START_DATA(dump), dump.u_dsize << PAGE_SHIFT))
110                 dump.u_dsize = 0;
111         if (!access_ok(VERIFY_READ, START_STACK(dump), dump.u_ssize << PAGE_SHIFT))
112                 dump.u_ssize = 0;
113
114         set_fs(KERNEL_DS);
115 /* struct user */
116         if (!dump_write(file, &dump, sizeof(dump)))
117                 goto end_coredump;
118 /* Now dump all of the user data.  Include malloced stuff as well */
119         if (!dump_seek(cprm->file, PAGE_SIZE - sizeof(dump)))
120                 goto end_coredump;
121 /* now we start writing out the user space info */
122         set_fs(USER_DS);
123 /* Dump the data area */
124         if (dump.u_dsize != 0) {
125                 dump_start = START_DATA(dump);
126                 dump_size = dump.u_dsize << PAGE_SHIFT;
127                 if (!dump_write(file, dump_start, dump_size))
128                         goto end_coredump;
129         }
130 /* Now prepare to dump the stack area */
131         if (dump.u_ssize != 0) {
132                 dump_start = START_STACK(dump);
133                 dump_size = dump.u_ssize << PAGE_SHIFT;
134                 if (!dump_write(file, dump_start, dump_size))
135                         goto end_coredump;
136         }
137 /* Finally dump the task struct.  Not be used by gdb, but could be useful */
138         set_fs(KERNEL_DS);
139         if (!dump_write(file, current, sizeof(*current)))
140                 goto end_coredump;
141 end_coredump:
142         set_fs(fs);
143         return has_dumped;
144 }
145
146 /*
147  * create_aout_tables() parses the env- and arg-strings in new user
148  * memory and creates the pointer tables from them, and puts their
149  * addresses on the "stack", returning the new stack pointer value.
150  */
151 static unsigned long __user *create_aout_tables(char __user *p, struct linux_binprm * bprm)
152 {
153         char __user * __user *argv;
154         char __user * __user *envp;
155         unsigned long __user *sp;
156         int argc = bprm->argc;
157         int envc = bprm->envc;
158
159         sp = (void __user *)((-(unsigned long)sizeof(char *)) & (unsigned long) p);
160 #ifdef __alpha__
161 /* whee.. test-programs are so much fun. */
162         put_user(0, --sp);
163         put_user(0, --sp);
164         if (bprm->loader) {
165                 put_user(0, --sp);
166                 put_user(1003, --sp);
167                 put_user(bprm->loader, --sp);
168                 put_user(1002, --sp);
169         }
170         put_user(bprm->exec, --sp);
171         put_user(1001, --sp);
172 #endif
173         sp -= envc+1;
174         envp = (char __user * __user *) sp;
175         sp -= argc+1;
176         argv = (char __user * __user *) sp;
177 #ifndef __alpha__
178         put_user((unsigned long) envp,--sp);
179         put_user((unsigned long) argv,--sp);
180 #endif
181         put_user(argc,--sp);
182         current->mm->arg_start = (unsigned long) p;
183         while (argc-->0) {
184                 char c;
185                 put_user(p,argv++);
186                 do {
187                         get_user(c,p++);
188                 } while (c);
189         }
190         put_user(NULL,argv);
191         current->mm->arg_end = current->mm->env_start = (unsigned long) p;
192         while (envc-->0) {
193                 char c;
194                 put_user(p,envp++);
195                 do {
196                         get_user(c,p++);
197                 } while (c);
198         }
199         put_user(NULL,envp);
200         current->mm->env_end = (unsigned long) p;
201         return sp;
202 }
203
204 /*
205  * These are the functions used to load a.out style executables and shared
206  * libraries.  There is no binary dependent code anywhere else.
207  */
208
209 static int load_aout_binary(struct linux_binprm * bprm, struct pt_regs * regs)
210 {
211         struct exec ex;
212         unsigned long error;
213         unsigned long fd_offset;
214         unsigned long rlim;
215         int retval;
216
217         ex = *((struct exec *) bprm->buf);              /* exec-header */
218         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
219              N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
220             N_TRSIZE(ex) || N_DRSIZE(ex) ||
221             i_size_read(bprm->file->f_path.dentry->d_inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
222                 return -ENOEXEC;
223         }
224
225         /*
226          * Requires a mmap handler. This prevents people from using a.out
227          * as part of an exploit attack against /proc-related vulnerabilities.
228          */
229         if (!bprm->file->f_op || !bprm->file->f_op->mmap)
230                 return -ENOEXEC;
231
232         fd_offset = N_TXTOFF(ex);
233
234         /* Check initial limits. This avoids letting people circumvent
235          * size limits imposed on them by creating programs with large
236          * arrays in the data or bss.
237          */
238         rlim = rlimit(RLIMIT_DATA);
239         if (rlim >= RLIM_INFINITY)
240                 rlim = ~0;
241         if (ex.a_data + ex.a_bss > rlim)
242                 return -ENOMEM;
243
244         /* Flush all traces of the currently running executable */
245         retval = flush_old_exec(bprm);
246         if (retval)
247                 return retval;
248
249         /* OK, This is the point of no return */
250 #ifdef __alpha__
251         SET_AOUT_PERSONALITY(bprm, ex);
252 #else
253         set_personality(PER_LINUX);
254 #endif
255         setup_new_exec(bprm);
256
257         current->mm->end_code = ex.a_text +
258                 (current->mm->start_code = N_TXTADDR(ex));
259         current->mm->end_data = ex.a_data +
260                 (current->mm->start_data = N_DATADDR(ex));
261         current->mm->brk = ex.a_bss +
262                 (current->mm->start_brk = N_BSSADDR(ex));
263         current->mm->free_area_cache = current->mm->mmap_base;
264         current->mm->cached_hole_size = 0;
265
266         install_exec_creds(bprm);
267         current->flags &= ~PF_FORKNOEXEC;
268
269         if (N_MAGIC(ex) == OMAGIC) {
270                 unsigned long text_addr, map_size;
271                 loff_t pos;
272
273                 text_addr = N_TXTADDR(ex);
274
275 #ifdef __alpha__
276                 pos = fd_offset;
277                 map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
278 #else
279                 pos = 32;
280                 map_size = ex.a_text+ex.a_data;
281 #endif
282                 down_write(&current->mm->mmap_sem);
283                 error = do_brk(text_addr & PAGE_MASK, map_size);
284                 up_write(&current->mm->mmap_sem);
285                 if (error != (text_addr & PAGE_MASK)) {
286                         send_sig(SIGKILL, current, 0);
287                         return error;
288                 }
289
290                 error = bprm->file->f_op->read(bprm->file,
291                           (char __user *)text_addr,
292                           ex.a_text+ex.a_data, &pos);
293                 if ((signed long)error < 0) {
294                         send_sig(SIGKILL, current, 0);
295                         return error;
296                 }
297                          
298                 flush_icache_range(text_addr, text_addr+ex.a_text+ex.a_data);
299         } else {
300                 if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
301                     (N_MAGIC(ex) != NMAGIC) && printk_ratelimit())
302                 {
303                         printk(KERN_NOTICE "executable not page aligned\n");
304                 }
305
306                 if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit())
307                 {
308                         printk(KERN_WARNING 
309                                "fd_offset is not page aligned. Please convert program: %s\n",
310                                bprm->file->f_path.dentry->d_name.name);
311                 }
312
313                 if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
314                         loff_t pos = fd_offset;
315                         down_write(&current->mm->mmap_sem);
316                         do_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
317                         up_write(&current->mm->mmap_sem);
318                         bprm->file->f_op->read(bprm->file,
319                                         (char __user *)N_TXTADDR(ex),
320                                         ex.a_text+ex.a_data, &pos);
321                         flush_icache_range((unsigned long) N_TXTADDR(ex),
322                                            (unsigned long) N_TXTADDR(ex) +
323                                            ex.a_text+ex.a_data);
324                         goto beyond_if;
325                 }
326
327                 down_write(&current->mm->mmap_sem);
328                 error = do_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
329                         PROT_READ | PROT_EXEC,
330                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
331                         fd_offset);
332                 up_write(&current->mm->mmap_sem);
333
334                 if (error != N_TXTADDR(ex)) {
335                         send_sig(SIGKILL, current, 0);
336                         return error;
337                 }
338
339                 down_write(&current->mm->mmap_sem);
340                 error = do_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
341                                 PROT_READ | PROT_WRITE | PROT_EXEC,
342                                 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
343                                 fd_offset + ex.a_text);
344                 up_write(&current->mm->mmap_sem);
345                 if (error != N_DATADDR(ex)) {
346                         send_sig(SIGKILL, current, 0);
347                         return error;
348                 }
349         }
350 beyond_if:
351         set_binfmt(&aout_format);
352
353         retval = set_brk(current->mm->start_brk, current->mm->brk);
354         if (retval < 0) {
355                 send_sig(SIGKILL, current, 0);
356                 return retval;
357         }
358
359         retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
360         if (retval < 0) { 
361                 /* Someone check-me: is this error path enough? */ 
362                 send_sig(SIGKILL, current, 0); 
363                 return retval;
364         }
365
366         current->mm->start_stack =
367                 (unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
368 #ifdef __alpha__
369         regs->gp = ex.a_gpvalue;
370 #endif
371         start_thread(regs, ex.a_entry, current->mm->start_stack);
372         return 0;
373 }
374
375 static int load_aout_library(struct file *file)
376 {
377         struct inode * inode;
378         unsigned long bss, start_addr, len;
379         unsigned long error;
380         int retval;
381         struct exec ex;
382
383         inode = file->f_path.dentry->d_inode;
384
385         retval = -ENOEXEC;
386         error = kernel_read(file, 0, (char *) &ex, sizeof(ex));
387         if (error != sizeof(ex))
388                 goto out;
389
390         /* We come in here for the regular a.out style of shared libraries */
391         if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
392             N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
393             i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
394                 goto out;
395         }
396
397         /*
398          * Requires a mmap handler. This prevents people from using a.out
399          * as part of an exploit attack against /proc-related vulnerabilities.
400          */
401         if (!file->f_op || !file->f_op->mmap)
402                 goto out;
403
404         if (N_FLAGS(ex))
405                 goto out;
406
407         /* For  QMAGIC, the starting address is 0x20 into the page.  We mask
408            this off to get the starting address for the page */
409
410         start_addr =  ex.a_entry & 0xfffff000;
411
412         if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
413                 loff_t pos = N_TXTOFF(ex);
414
415                 if (printk_ratelimit())
416                 {
417                         printk(KERN_WARNING 
418                                "N_TXTOFF is not page aligned. Please convert library: %s\n",
419                                file->f_path.dentry->d_name.name);
420                 }
421                 down_write(&current->mm->mmap_sem);
422                 do_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
423                 up_write(&current->mm->mmap_sem);
424                 
425                 file->f_op->read(file, (char __user *)start_addr,
426                         ex.a_text + ex.a_data, &pos);
427                 flush_icache_range((unsigned long) start_addr,
428                                    (unsigned long) start_addr + ex.a_text + ex.a_data);
429
430                 retval = 0;
431                 goto out;
432         }
433         /* Now use mmap to map the library into memory. */
434         down_write(&current->mm->mmap_sem);
435         error = do_mmap(file, start_addr, ex.a_text + ex.a_data,
436                         PROT_READ | PROT_WRITE | PROT_EXEC,
437                         MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
438                         N_TXTOFF(ex));
439         up_write(&current->mm->mmap_sem);
440         retval = error;
441         if (error != start_addr)
442                 goto out;
443
444         len = PAGE_ALIGN(ex.a_text + ex.a_data);
445         bss = ex.a_text + ex.a_data + ex.a_bss;
446         if (bss > len) {
447                 down_write(&current->mm->mmap_sem);
448                 error = do_brk(start_addr + len, bss - len);
449                 up_write(&current->mm->mmap_sem);
450                 retval = error;
451                 if (error != start_addr + len)
452                         goto out;
453         }
454         retval = 0;
455 out:
456         return retval;
457 }
458
459 static int __init init_aout_binfmt(void)
460 {
461         return register_binfmt(&aout_format);
462 }
463
464 static void __exit exit_aout_binfmt(void)
465 {
466         unregister_binfmt(&aout_format);
467 }
468
469 core_initcall(init_aout_binfmt);
470 module_exit(exit_aout_binfmt);
471 MODULE_LICENSE("GPL");