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