/fs/binfmt_aout.c
C | 481 lines | 365 code | 59 blank | 57 comment | 76 complexity | 8745cb0288db7ff04c907831d4ce481f MD5 | raw file
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
33static int load_aout_binary(struct linux_binprm *, struct pt_regs * regs);
34static int load_aout_library(struct file*);
35static int aout_core_dump(long signr, struct pt_regs *regs, struct file *file, unsigned long limit);
36
37static 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
47static 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(¤t->mm->mmap_sem);
54 addr = do_brk(start, end - start);
55 up_write(¤t->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
67static 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) \
77if (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
92static 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));
152end_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 */
162static 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
220static 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(¤t->mm->mmap_sem);
293 error = do_brk(text_addr & PAGE_MASK, map_size);
294 up_write(¤t->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(¤t->mm->mmap_sem);
326 do_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
327 up_write(¤t->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(¤t->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(¤t->mm->mmap_sem);
343
344 if (error != N_TXTADDR(ex)) {
345 send_sig(SIGKILL, current, 0);
346 return error;
347 }
348
349 down_write(¤t->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(¤t->mm->mmap_sem);
355 if (error != N_DATADDR(ex)) {
356 send_sig(SIGKILL, current, 0);
357 return error;
358 }
359 }
360beyond_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
385static 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(¤t->mm->mmap_sem);
432 do_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
433 up_write(¤t->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(¤t->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(¤t->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(¤t->mm->mmap_sem);
458 error = do_brk(start_addr + len, bss - len);
459 up_write(¤t->mm->mmap_sem);
460 retval = error;
461 if (error != start_addr + len)
462 goto out;
463 }
464 retval = 0;
465out:
466 return retval;
467}
468
469static int __init init_aout_binfmt(void)
470{
471 return register_binfmt(&aout_format);
472}
473
474static void __exit exit_aout_binfmt(void)
475{
476 unregister_binfmt(&aout_format);
477}
478
479core_initcall(init_aout_binfmt);
480module_exit(exit_aout_binfmt);
481MODULE_LICENSE("GPL");