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 *);
34 static int load_aout_library(struct file*);
35
36 #ifdef CONFIG_COREDUMP
37 /*
38 * Routine writes a core dump image in the current directory.
39 * Currently only a stub-function.
40 *
41 * Note that setuid/setgid files won't make a core-dump if the uid/gid
42 * changed due to the set[u|g]id. It's enforced by the "current->mm->dumpable"
43 * field, which also makes sure the core-dumps won't be recursive if the
44 * dumping of the process results in another error..
45 */
aout_core_dump(struct coredump_params * cprm)46 static int aout_core_dump(struct coredump_params *cprm)
47 {
48 struct file *file = cprm->file;
49 mm_segment_t fs;
50 int has_dumped = 0;
51 void __user *dump_start;
52 int dump_size;
53 struct user dump;
54 #ifdef __alpha__
55 # define START_DATA(u) ((void __user *)u.start_data)
56 #else
57 # define START_DATA(u) ((void __user *)((u.u_tsize << PAGE_SHIFT) + \
58 u.start_code))
59 #endif
60 # define START_STACK(u) ((void __user *)u.start_stack)
61
62 fs = get_fs();
63 set_fs(KERNEL_DS);
64 has_dumped = 1;
65 strncpy(dump.u_comm, current->comm, sizeof(dump.u_comm));
66 dump.u_ar0 = offsetof(struct user, regs);
67 dump.signal = cprm->siginfo->si_signo;
68 aout_dump_thread(cprm->regs, &dump);
69
70 /* If the size of the dump file exceeds the rlimit, then see what would happen
71 if we wrote the stack, but not the data area. */
72 if ((dump.u_dsize + dump.u_ssize+1) * PAGE_SIZE > cprm->limit)
73 dump.u_dsize = 0;
74
75 /* Make sure we have enough room to write the stack and data areas. */
76 if ((dump.u_ssize + 1) * PAGE_SIZE > cprm->limit)
77 dump.u_ssize = 0;
78
79 /* make sure we actually have a data and stack area to dump */
80 set_fs(USER_DS);
81 if (!access_ok(VERIFY_READ, START_DATA(dump), dump.u_dsize << PAGE_SHIFT))
82 dump.u_dsize = 0;
83 if (!access_ok(VERIFY_READ, START_STACK(dump), dump.u_ssize << PAGE_SHIFT))
84 dump.u_ssize = 0;
85
86 set_fs(KERNEL_DS);
87 /* struct user */
88 if (!dump_write(file, &dump, sizeof(dump)))
89 goto end_coredump;
90 /* Now dump all of the user data. Include malloced stuff as well */
91 if (!dump_seek(cprm->file, PAGE_SIZE - sizeof(dump)))
92 goto end_coredump;
93 /* now we start writing out the user space info */
94 set_fs(USER_DS);
95 /* Dump the data area */
96 if (dump.u_dsize != 0) {
97 dump_start = START_DATA(dump);
98 dump_size = dump.u_dsize << PAGE_SHIFT;
99 if (!dump_write(file, dump_start, dump_size))
100 goto end_coredump;
101 }
102 /* Now prepare to dump the stack area */
103 if (dump.u_ssize != 0) {
104 dump_start = START_STACK(dump);
105 dump_size = dump.u_ssize << PAGE_SHIFT;
106 if (!dump_write(file, dump_start, dump_size))
107 goto end_coredump;
108 }
109 end_coredump:
110 set_fs(fs);
111 return has_dumped;
112 }
113 #else
114 #define aout_core_dump NULL
115 #endif
116
117 static struct linux_binfmt aout_format = {
118 .module = THIS_MODULE,
119 .load_binary = load_aout_binary,
120 .load_shlib = load_aout_library,
121 .core_dump = aout_core_dump,
122 .min_coredump = PAGE_SIZE
123 };
124
125 #define BAD_ADDR(x) ((unsigned long)(x) >= TASK_SIZE)
126
set_brk(unsigned long start,unsigned long end)127 static int set_brk(unsigned long start, unsigned long end)
128 {
129 start = PAGE_ALIGN(start);
130 end = PAGE_ALIGN(end);
131 if (end > start) {
132 unsigned long addr;
133 addr = vm_brk(start, end - start);
134 if (BAD_ADDR(addr))
135 return addr;
136 }
137 return 0;
138 }
139
140 /*
141 * create_aout_tables() parses the env- and arg-strings in new user
142 * memory and creates the pointer tables from them, and puts their
143 * addresses on the "stack", returning the new stack pointer value.
144 */
create_aout_tables(char __user * p,struct linux_binprm * bprm)145 static unsigned long __user *create_aout_tables(char __user *p, struct linux_binprm * bprm)
146 {
147 char __user * __user *argv;
148 char __user * __user *envp;
149 unsigned long __user *sp;
150 int argc = bprm->argc;
151 int envc = bprm->envc;
152
153 sp = (void __user *)((-(unsigned long)sizeof(char *)) & (unsigned long) p);
154 #ifdef __alpha__
155 /* whee.. test-programs are so much fun. */
156 put_user(0, --sp);
157 put_user(0, --sp);
158 if (bprm->loader) {
159 put_user(0, --sp);
160 put_user(1003, --sp);
161 put_user(bprm->loader, --sp);
162 put_user(1002, --sp);
163 }
164 put_user(bprm->exec, --sp);
165 put_user(1001, --sp);
166 #endif
167 sp -= envc+1;
168 envp = (char __user * __user *) sp;
169 sp -= argc+1;
170 argv = (char __user * __user *) sp;
171 #ifndef __alpha__
172 put_user((unsigned long) envp,--sp);
173 put_user((unsigned long) argv,--sp);
174 #endif
175 put_user(argc,--sp);
176 current->mm->arg_start = (unsigned long) p;
177 while (argc-->0) {
178 char c;
179 put_user(p,argv++);
180 do {
181 get_user(c,p++);
182 } while (c);
183 }
184 put_user(NULL,argv);
185 current->mm->arg_end = current->mm->env_start = (unsigned long) p;
186 while (envc-->0) {
187 char c;
188 put_user(p,envp++);
189 do {
190 get_user(c,p++);
191 } while (c);
192 }
193 put_user(NULL,envp);
194 current->mm->env_end = (unsigned long) p;
195 return sp;
196 }
197
198 /*
199 * These are the functions used to load a.out style executables and shared
200 * libraries. There is no binary dependent code anywhere else.
201 */
202
load_aout_binary(struct linux_binprm * bprm)203 static int load_aout_binary(struct linux_binprm * bprm)
204 {
205 struct pt_regs *regs = current_pt_regs();
206 struct exec ex;
207 unsigned long error;
208 unsigned long fd_offset;
209 unsigned long rlim;
210 int retval;
211
212 ex = *((struct exec *) bprm->buf); /* exec-header */
213 if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
214 N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
215 N_TRSIZE(ex) || N_DRSIZE(ex) ||
216 i_size_read(file_inode(bprm->file)) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
217 return -ENOEXEC;
218 }
219
220 /*
221 * Requires a mmap handler. This prevents people from using a.out
222 * as part of an exploit attack against /proc-related vulnerabilities.
223 */
224 if (!bprm->file->f_op || !bprm->file->f_op->mmap)
225 return -ENOEXEC;
226
227 fd_offset = N_TXTOFF(ex);
228
229 /* Check initial limits. This avoids letting people circumvent
230 * size limits imposed on them by creating programs with large
231 * arrays in the data or bss.
232 */
233 rlim = rlimit(RLIMIT_DATA);
234 if (rlim >= RLIM_INFINITY)
235 rlim = ~0;
236 if (ex.a_data + ex.a_bss > rlim)
237 return -ENOMEM;
238
239 /* Flush all traces of the currently running executable */
240 retval = flush_old_exec(bprm);
241 if (retval)
242 return retval;
243
244 /* OK, This is the point of no return */
245 #ifdef __alpha__
246 SET_AOUT_PERSONALITY(bprm, ex);
247 #else
248 set_personality(PER_LINUX);
249 #endif
250 setup_new_exec(bprm);
251
252 current->mm->end_code = ex.a_text +
253 (current->mm->start_code = N_TXTADDR(ex));
254 current->mm->end_data = ex.a_data +
255 (current->mm->start_data = N_DATADDR(ex));
256 current->mm->brk = ex.a_bss +
257 (current->mm->start_brk = N_BSSADDR(ex));
258 current->mm->free_area_cache = current->mm->mmap_base;
259 current->mm->cached_hole_size = 0;
260
261 retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
262 if (retval < 0) {
263 /* Someone check-me: is this error path enough? */
264 send_sig(SIGKILL, current, 0);
265 return retval;
266 }
267
268 install_exec_creds(bprm);
269
270 if (N_MAGIC(ex) == OMAGIC) {
271 unsigned long text_addr, map_size;
272 loff_t pos;
273
274 text_addr = N_TXTADDR(ex);
275
276 #ifdef __alpha__
277 pos = fd_offset;
278 map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
279 #else
280 pos = 32;
281 map_size = ex.a_text+ex.a_data;
282 #endif
283 error = vm_brk(text_addr & PAGE_MASK, map_size);
284 if (error != (text_addr & PAGE_MASK)) {
285 send_sig(SIGKILL, current, 0);
286 return error;
287 }
288
289 error = read_code(bprm->file, text_addr, pos,
290 ex.a_text+ex.a_data);
291 if ((signed long)error < 0) {
292 send_sig(SIGKILL, current, 0);
293 return error;
294 }
295 } else {
296 if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
297 (N_MAGIC(ex) != NMAGIC) && printk_ratelimit())
298 {
299 printk(KERN_NOTICE "executable not page aligned\n");
300 }
301
302 if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit())
303 {
304 printk(KERN_WARNING
305 "fd_offset is not page aligned. Please convert program: %s\n",
306 bprm->file->f_path.dentry->d_name.name);
307 }
308
309 if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
310 vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
311 read_code(bprm->file, N_TXTADDR(ex), fd_offset,
312 ex.a_text + ex.a_data);
313 goto beyond_if;
314 }
315
316 error = vm_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
317 PROT_READ | PROT_EXEC,
318 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
319 fd_offset);
320
321 if (error != N_TXTADDR(ex)) {
322 send_sig(SIGKILL, current, 0);
323 return error;
324 }
325
326 error = vm_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
327 PROT_READ | PROT_WRITE | PROT_EXEC,
328 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
329 fd_offset + ex.a_text);
330 if (error != N_DATADDR(ex)) {
331 send_sig(SIGKILL, current, 0);
332 return error;
333 }
334 }
335 beyond_if:
336 set_binfmt(&aout_format);
337
338 retval = set_brk(current->mm->start_brk, current->mm->brk);
339 if (retval < 0) {
340 send_sig(SIGKILL, current, 0);
341 return retval;
342 }
343
344 current->mm->start_stack =
345 (unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
346 #ifdef __alpha__
347 regs->gp = ex.a_gpvalue;
348 #endif
349 start_thread(regs, ex.a_entry, current->mm->start_stack);
350 return 0;
351 }
352
load_aout_library(struct file * file)353 static int load_aout_library(struct file *file)
354 {
355 struct inode * inode;
356 unsigned long bss, start_addr, len;
357 unsigned long error;
358 int retval;
359 struct exec ex;
360
361 inode = file_inode(file);
362
363 retval = -ENOEXEC;
364 error = kernel_read(file, 0, (char *) &ex, sizeof(ex));
365 if (error != sizeof(ex))
366 goto out;
367
368 /* We come in here for the regular a.out style of shared libraries */
369 if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
370 N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
371 i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
372 goto out;
373 }
374
375 /*
376 * Requires a mmap handler. This prevents people from using a.out
377 * as part of an exploit attack against /proc-related vulnerabilities.
378 */
379 if (!file->f_op || !file->f_op->mmap)
380 goto out;
381
382 if (N_FLAGS(ex))
383 goto out;
384
385 /* For QMAGIC, the starting address is 0x20 into the page. We mask
386 this off to get the starting address for the page */
387
388 start_addr = ex.a_entry & 0xfffff000;
389
390 if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
391 if (printk_ratelimit())
392 {
393 printk(KERN_WARNING
394 "N_TXTOFF is not page aligned. Please convert library: %s\n",
395 file->f_path.dentry->d_name.name);
396 }
397 vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
398
399 read_code(file, start_addr, N_TXTOFF(ex),
400 ex.a_text + ex.a_data);
401 retval = 0;
402 goto out;
403 }
404 /* Now use mmap to map the library into memory. */
405 error = vm_mmap(file, start_addr, ex.a_text + ex.a_data,
406 PROT_READ | PROT_WRITE | PROT_EXEC,
407 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
408 N_TXTOFF(ex));
409 retval = error;
410 if (error != start_addr)
411 goto out;
412
413 len = PAGE_ALIGN(ex.a_text + ex.a_data);
414 bss = ex.a_text + ex.a_data + ex.a_bss;
415 if (bss > len) {
416 error = vm_brk(start_addr + len, bss - len);
417 retval = error;
418 if (error != start_addr + len)
419 goto out;
420 }
421 retval = 0;
422 out:
423 return retval;
424 }
425
init_aout_binfmt(void)426 static int __init init_aout_binfmt(void)
427 {
428 register_binfmt(&aout_format);
429 return 0;
430 }
431
exit_aout_binfmt(void)432 static void __exit exit_aout_binfmt(void)
433 {
434 unregister_binfmt(&aout_format);
435 }
436
437 core_initcall(init_aout_binfmt);
438 module_exit(exit_aout_binfmt);
439 MODULE_LICENSE("GPL");
440