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