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 #include <linux/sched/task_stack.h>
29
30 #include <linux/uaccess.h>
31 #include <asm/cacheflush.h>
32 #include <asm/a.out-core.h>
33
34 static int load_aout_binary(struct linux_binprm *);
35 static int load_aout_library(struct file*);
36
37 #ifdef CONFIG_COREDUMP
38 /*
39 * Routine writes a core dump image in the current directory.
40 * Currently only a stub-function.
41 *
42 * Note that setuid/setgid files won't make a core-dump if the uid/gid
43 * changed due to the set[u|g]id. It's enforced by the "current->mm->dumpable"
44 * field, which also makes sure the core-dumps won't be recursive if the
45 * dumping of the process results in another error..
46 */
aout_core_dump(struct coredump_params * cprm)47 static int aout_core_dump(struct coredump_params *cprm)
48 {
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_emit(cprm, &dump, sizeof(dump)))
89 goto end_coredump;
90 /* Now dump all of the user data. Include malloced stuff as well */
91 if (!dump_skip(cprm, 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_emit(cprm, 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_emit(cprm, 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 return vm_brk(start, end - start);
133 return 0;
134 }
135
136 /*
137 * create_aout_tables() parses the env- and arg-strings in new user
138 * memory and creates the pointer tables from them, and puts their
139 * addresses on the "stack", returning the new stack pointer value.
140 */
create_aout_tables(char __user * p,struct linux_binprm * bprm)141 static unsigned long __user *create_aout_tables(char __user *p, struct linux_binprm * bprm)
142 {
143 char __user * __user *argv;
144 char __user * __user *envp;
145 unsigned long __user *sp;
146 int argc = bprm->argc;
147 int envc = bprm->envc;
148
149 sp = (void __user *)((-(unsigned long)sizeof(char *)) & (unsigned long) p);
150 #ifdef __alpha__
151 /* whee.. test-programs are so much fun. */
152 put_user(0, --sp);
153 put_user(0, --sp);
154 if (bprm->loader) {
155 put_user(0, --sp);
156 put_user(1003, --sp);
157 put_user(bprm->loader, --sp);
158 put_user(1002, --sp);
159 }
160 put_user(bprm->exec, --sp);
161 put_user(1001, --sp);
162 #endif
163 sp -= envc+1;
164 envp = (char __user * __user *) sp;
165 sp -= argc+1;
166 argv = (char __user * __user *) sp;
167 #ifndef __alpha__
168 put_user((unsigned long) envp,--sp);
169 put_user((unsigned long) argv,--sp);
170 #endif
171 put_user(argc,--sp);
172 current->mm->arg_start = (unsigned long) p;
173 while (argc-->0) {
174 char c;
175 put_user(p,argv++);
176 do {
177 get_user(c,p++);
178 } while (c);
179 }
180 put_user(NULL,argv);
181 current->mm->arg_end = current->mm->env_start = (unsigned long) p;
182 while (envc-->0) {
183 char c;
184 put_user(p,envp++);
185 do {
186 get_user(c,p++);
187 } while (c);
188 }
189 put_user(NULL,envp);
190 current->mm->env_end = (unsigned long) p;
191 return sp;
192 }
193
194 /*
195 * These are the functions used to load a.out style executables and shared
196 * libraries. There is no binary dependent code anywhere else.
197 */
198
load_aout_binary(struct linux_binprm * bprm)199 static int load_aout_binary(struct linux_binprm * bprm)
200 {
201 struct pt_regs *regs = current_pt_regs();
202 struct exec ex;
203 unsigned long error;
204 unsigned long fd_offset;
205 unsigned long rlim;
206 int retval;
207
208 ex = *((struct exec *) bprm->buf); /* exec-header */
209 if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
210 N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
211 N_TRSIZE(ex) || N_DRSIZE(ex) ||
212 i_size_read(file_inode(bprm->file)) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
213 return -ENOEXEC;
214 }
215
216 /*
217 * Requires a mmap handler. This prevents people from using a.out
218 * as part of an exploit attack against /proc-related vulnerabilities.
219 */
220 if (!bprm->file->f_op->mmap)
221 return -ENOEXEC;
222
223 fd_offset = N_TXTOFF(ex);
224
225 /* Check initial limits. This avoids letting people circumvent
226 * size limits imposed on them by creating programs with large
227 * arrays in the data or bss.
228 */
229 rlim = rlimit(RLIMIT_DATA);
230 if (rlim >= RLIM_INFINITY)
231 rlim = ~0;
232 if (ex.a_data + ex.a_bss > rlim)
233 return -ENOMEM;
234
235 /* Flush all traces of the currently running executable */
236 retval = flush_old_exec(bprm);
237 if (retval)
238 return retval;
239
240 /* OK, This is the point of no return */
241 #ifdef __alpha__
242 SET_AOUT_PERSONALITY(bprm, ex);
243 #else
244 set_personality(PER_LINUX);
245 #endif
246 setup_new_exec(bprm);
247
248 current->mm->end_code = ex.a_text +
249 (current->mm->start_code = N_TXTADDR(ex));
250 current->mm->end_data = ex.a_data +
251 (current->mm->start_data = N_DATADDR(ex));
252 current->mm->brk = ex.a_bss +
253 (current->mm->start_brk = N_BSSADDR(ex));
254
255 retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
256 if (retval < 0)
257 return retval;
258
259 install_exec_creds(bprm);
260
261 if (N_MAGIC(ex) == OMAGIC) {
262 unsigned long text_addr, map_size;
263 loff_t pos;
264
265 text_addr = N_TXTADDR(ex);
266
267 #ifdef __alpha__
268 pos = fd_offset;
269 map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
270 #else
271 pos = 32;
272 map_size = ex.a_text+ex.a_data;
273 #endif
274 error = vm_brk(text_addr & PAGE_MASK, map_size);
275 if (error)
276 return error;
277
278 error = read_code(bprm->file, text_addr, pos,
279 ex.a_text+ex.a_data);
280 if ((signed long)error < 0)
281 return error;
282 } else {
283 if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
284 (N_MAGIC(ex) != NMAGIC) && printk_ratelimit())
285 {
286 printk(KERN_NOTICE "executable not page aligned\n");
287 }
288
289 if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit())
290 {
291 printk(KERN_WARNING
292 "fd_offset is not page aligned. Please convert program: %pD\n",
293 bprm->file);
294 }
295
296 if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
297 error = vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
298 if (error)
299 return error;
300
301 read_code(bprm->file, N_TXTADDR(ex), fd_offset,
302 ex.a_text + ex.a_data);
303 goto beyond_if;
304 }
305
306 error = vm_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
307 PROT_READ | PROT_EXEC,
308 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
309 fd_offset);
310
311 if (error != N_TXTADDR(ex))
312 return error;
313
314 error = vm_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
315 PROT_READ | PROT_WRITE | PROT_EXEC,
316 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
317 fd_offset + ex.a_text);
318 if (error != N_DATADDR(ex))
319 return error;
320 }
321 beyond_if:
322 set_binfmt(&aout_format);
323
324 retval = set_brk(current->mm->start_brk, current->mm->brk);
325 if (retval < 0)
326 return retval;
327
328 current->mm->start_stack =
329 (unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
330 #ifdef __alpha__
331 regs->gp = ex.a_gpvalue;
332 #endif
333 finalize_exec(bprm);
334 start_thread(regs, ex.a_entry, current->mm->start_stack);
335 return 0;
336 }
337
load_aout_library(struct file * file)338 static int load_aout_library(struct file *file)
339 {
340 struct inode * inode;
341 unsigned long bss, start_addr, len;
342 unsigned long error;
343 int retval;
344 struct exec ex;
345 loff_t pos = 0;
346
347 inode = file_inode(file);
348
349 retval = -ENOEXEC;
350 error = kernel_read(file, &ex, sizeof(ex), &pos);
351 if (error != sizeof(ex))
352 goto out;
353
354 /* We come in here for the regular a.out style of shared libraries */
355 if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
356 N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
357 i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
358 goto out;
359 }
360
361 /*
362 * Requires a mmap handler. This prevents people from using a.out
363 * as part of an exploit attack against /proc-related vulnerabilities.
364 */
365 if (!file->f_op->mmap)
366 goto out;
367
368 if (N_FLAGS(ex))
369 goto out;
370
371 /* For QMAGIC, the starting address is 0x20 into the page. We mask
372 this off to get the starting address for the page */
373
374 start_addr = ex.a_entry & 0xfffff000;
375
376 if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
377 if (printk_ratelimit())
378 {
379 printk(KERN_WARNING
380 "N_TXTOFF is not page aligned. Please convert library: %pD\n",
381 file);
382 }
383 retval = vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
384 if (retval)
385 goto out;
386
387 read_code(file, start_addr, N_TXTOFF(ex),
388 ex.a_text + ex.a_data);
389 retval = 0;
390 goto out;
391 }
392 /* Now use mmap to map the library into memory. */
393 error = vm_mmap(file, start_addr, ex.a_text + ex.a_data,
394 PROT_READ | PROT_WRITE | PROT_EXEC,
395 MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
396 N_TXTOFF(ex));
397 retval = error;
398 if (error != start_addr)
399 goto out;
400
401 len = PAGE_ALIGN(ex.a_text + ex.a_data);
402 bss = ex.a_text + ex.a_data + ex.a_bss;
403 if (bss > len) {
404 retval = vm_brk(start_addr + len, bss - len);
405 if (retval)
406 goto out;
407 }
408 retval = 0;
409 out:
410 return retval;
411 }
412
init_aout_binfmt(void)413 static int __init init_aout_binfmt(void)
414 {
415 register_binfmt(&aout_format);
416 return 0;
417 }
418
exit_aout_binfmt(void)419 static void __exit exit_aout_binfmt(void)
420 {
421 unregister_binfmt(&aout_format);
422 }
423
424 core_initcall(init_aout_binfmt);
425 module_exit(exit_aout_binfmt);
426 MODULE_LICENSE("GPL");
427
