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