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