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/fs/binfmt_aout.c

https://github.com/concer/linux-2.6
C | 481 lines | 365 code | 59 blank | 57 comment | 76 complexity | 8745cb0288db7ff04c907831d4ce481f MD5 | raw file
  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/slab.h>
 24#include <linux/binfmts.h>
 25#include <linux/personality.h>
 26#include <linux/init.h>
 27
 28#include <asm/system.h>
 29#include <asm/uaccess.h>
 30#include <asm/cacheflush.h>
 31#include <asm/a.out-core.h>
 32
 33static int load_aout_binary(struct linux_binprm *, struct pt_regs * regs);
 34static int load_aout_library(struct file*);
 35static int aout_core_dump(long signr, struct pt_regs *regs, struct file *file, unsigned long limit);
 36
 37static 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
 47static 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		down_write(&current->mm->mmap_sem);
 54		addr = do_brk(start, end - start);
 55		up_write(&current->mm->mmap_sem);
 56		if (BAD_ADDR(addr))
 57			return addr;
 58	}
 59	return 0;
 60}
 61
 62/*
 63 * These are the only things you should do on a core-file: use only these
 64 * macros to write out all the necessary info.
 65 */
 66
 67static int dump_write(struct file *file, const void *addr, int nr)
 68{
 69	return file->f_op->write(file, addr, nr, &file->f_pos) == nr;
 70}
 71
 72#define DUMP_WRITE(addr, nr)	\
 73	if (!dump_write(file, (void *)(addr), (nr))) \
 74		goto end_coredump;
 75
 76#define DUMP_SEEK(offset) \
 77if (file->f_op->llseek) { \
 78	if (file->f_op->llseek(file,(offset),0) != (offset)) \
 79 		goto end_coredump; \
 80} else file->f_pos = (offset)
 81
 82/*
 83 * Routine writes a core dump image in the current directory.
 84 * Currently only a stub-function.
 85 *
 86 * Note that setuid/setgid files won't make a core-dump if the uid/gid
 87 * changed due to the set[u|g]id. It's enforced by the "current->mm->dumpable"
 88 * field, which also makes sure the core-dumps won't be recursive if the
 89 * dumping of the process results in another error..
 90 */
 91
 92static int aout_core_dump(long signr, struct pt_regs *regs, struct file *file, unsigned long limit)
 93{
 94	mm_segment_t fs;
 95	int has_dumped = 0;
 96	unsigned long dump_start, dump_size;
 97	struct user dump;
 98#ifdef __alpha__
 99#       define START_DATA(u)	(u.start_data)
100#else
101#	define START_DATA(u)	((u.u_tsize << PAGE_SHIFT) + u.start_code)
102#endif
103#       define START_STACK(u)   (u.start_stack)
104
105	fs = get_fs();
106	set_fs(KERNEL_DS);
107	has_dumped = 1;
108	current->flags |= PF_DUMPCORE;
109       	strncpy(dump.u_comm, current->comm, sizeof(dump.u_comm));
110	dump.u_ar0 = offsetof(struct user, regs);
111	dump.signal = signr;
112	aout_dump_thread(regs, &dump);
113
114/* If the size of the dump file exceeds the rlimit, then see what would happen
115   if we wrote the stack, but not the data area.  */
116	if ((dump.u_dsize + dump.u_ssize+1) * PAGE_SIZE > limit)
117		dump.u_dsize = 0;
118
119/* Make sure we have enough room to write the stack and data areas. */
120	if ((dump.u_ssize + 1) * PAGE_SIZE > limit)
121		dump.u_ssize = 0;
122
123/* make sure we actually have a data and stack area to dump */
124	set_fs(USER_DS);
125	if (!access_ok(VERIFY_READ, (void __user *)START_DATA(dump), dump.u_dsize << PAGE_SHIFT))
126		dump.u_dsize = 0;
127	if (!access_ok(VERIFY_READ, (void __user *)START_STACK(dump), dump.u_ssize << PAGE_SHIFT))
128		dump.u_ssize = 0;
129
130	set_fs(KERNEL_DS);
131/* struct user */
132	DUMP_WRITE(&dump,sizeof(dump));
133/* Now dump all of the user data.  Include malloced stuff as well */
134	DUMP_SEEK(PAGE_SIZE);
135/* now we start writing out the user space info */
136	set_fs(USER_DS);
137/* Dump the data area */
138	if (dump.u_dsize != 0) {
139		dump_start = START_DATA(dump);
140		dump_size = dump.u_dsize << PAGE_SHIFT;
141		DUMP_WRITE(dump_start,dump_size);
142	}
143/* Now prepare to dump the stack area */
144	if (dump.u_ssize != 0) {
145		dump_start = START_STACK(dump);
146		dump_size = dump.u_ssize << PAGE_SHIFT;
147		DUMP_WRITE(dump_start,dump_size);
148	}
149/* Finally dump the task struct.  Not be used by gdb, but could be useful */
150	set_fs(KERNEL_DS);
151	DUMP_WRITE(current,sizeof(*current));
152end_coredump:
153	set_fs(fs);
154	return has_dumped;
155}
156
157/*
158 * create_aout_tables() parses the env- and arg-strings in new user
159 * memory and creates the pointer tables from them, and puts their
160 * addresses on the "stack", returning the new stack pointer value.
161 */
162static unsigned long __user *create_aout_tables(char __user *p, struct linux_binprm * bprm)
163{
164	char __user * __user *argv;
165	char __user * __user *envp;
166	unsigned long __user *sp;
167	int argc = bprm->argc;
168	int envc = bprm->envc;
169
170	sp = (void __user *)((-(unsigned long)sizeof(char *)) & (unsigned long) p);
171#ifdef __alpha__
172/* whee.. test-programs are so much fun. */
173	put_user(0, --sp);
174	put_user(0, --sp);
175	if (bprm->loader) {
176		put_user(0, --sp);
177		put_user(1003, --sp);
178		put_user(bprm->loader, --sp);
179		put_user(1002, --sp);
180	}
181	put_user(bprm->exec, --sp);
182	put_user(1001, --sp);
183#endif
184	sp -= envc+1;
185	envp = (char __user * __user *) sp;
186	sp -= argc+1;
187	argv = (char __user * __user *) sp;
188#ifndef __alpha__
189	put_user((unsigned long) envp,--sp);
190	put_user((unsigned long) argv,--sp);
191#endif
192	put_user(argc,--sp);
193	current->mm->arg_start = (unsigned long) p;
194	while (argc-->0) {
195		char c;
196		put_user(p,argv++);
197		do {
198			get_user(c,p++);
199		} while (c);
200	}
201	put_user(NULL,argv);
202	current->mm->arg_end = current->mm->env_start = (unsigned long) p;
203	while (envc-->0) {
204		char c;
205		put_user(p,envp++);
206		do {
207			get_user(c,p++);
208		} while (c);
209	}
210	put_user(NULL,envp);
211	current->mm->env_end = (unsigned long) p;
212	return sp;
213}
214
215/*
216 * These are the functions used to load a.out style executables and shared
217 * libraries.  There is no binary dependent code anywhere else.
218 */
219
220static int load_aout_binary(struct linux_binprm * bprm, struct pt_regs * regs)
221{
222	struct exec ex;
223	unsigned long error;
224	unsigned long fd_offset;
225	unsigned long rlim;
226	int retval;
227
228	ex = *((struct exec *) bprm->buf);		/* exec-header */
229	if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
230	     N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
231	    N_TRSIZE(ex) || N_DRSIZE(ex) ||
232	    i_size_read(bprm->file->f_path.dentry->d_inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
233		return -ENOEXEC;
234	}
235
236	/*
237	 * Requires a mmap handler. This prevents people from using a.out
238	 * as part of an exploit attack against /proc-related vulnerabilities.
239	 */
240	if (!bprm->file->f_op || !bprm->file->f_op->mmap)
241		return -ENOEXEC;
242
243	fd_offset = N_TXTOFF(ex);
244
245	/* Check initial limits. This avoids letting people circumvent
246	 * size limits imposed on them by creating programs with large
247	 * arrays in the data or bss.
248	 */
249	rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
250	if (rlim >= RLIM_INFINITY)
251		rlim = ~0;
252	if (ex.a_data + ex.a_bss > rlim)
253		return -ENOMEM;
254
255	/* Flush all traces of the currently running executable */
256	retval = flush_old_exec(bprm);
257	if (retval)
258		return retval;
259
260	/* OK, This is the point of no return */
261#ifdef __alpha__
262	SET_AOUT_PERSONALITY(bprm, ex);
263#else
264	set_personality(PER_LINUX);
265#endif
266
267	current->mm->end_code = ex.a_text +
268		(current->mm->start_code = N_TXTADDR(ex));
269	current->mm->end_data = ex.a_data +
270		(current->mm->start_data = N_DATADDR(ex));
271	current->mm->brk = ex.a_bss +
272		(current->mm->start_brk = N_BSSADDR(ex));
273	current->mm->free_area_cache = current->mm->mmap_base;
274	current->mm->cached_hole_size = 0;
275
276	install_exec_creds(bprm);
277 	current->flags &= ~PF_FORKNOEXEC;
278
279	if (N_MAGIC(ex) == OMAGIC) {
280		unsigned long text_addr, map_size;
281		loff_t pos;
282
283		text_addr = N_TXTADDR(ex);
284
285#ifdef __alpha__
286		pos = fd_offset;
287		map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
288#else
289		pos = 32;
290		map_size = ex.a_text+ex.a_data;
291#endif
292		down_write(&current->mm->mmap_sem);
293		error = do_brk(text_addr & PAGE_MASK, map_size);
294		up_write(&current->mm->mmap_sem);
295		if (error != (text_addr & PAGE_MASK)) {
296			send_sig(SIGKILL, current, 0);
297			return error;
298		}
299
300		error = bprm->file->f_op->read(bprm->file,
301			  (char __user *)text_addr,
302			  ex.a_text+ex.a_data, &pos);
303		if ((signed long)error < 0) {
304			send_sig(SIGKILL, current, 0);
305			return error;
306		}
307			 
308		flush_icache_range(text_addr, text_addr+ex.a_text+ex.a_data);
309	} else {
310		if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
311		    (N_MAGIC(ex) != NMAGIC) && printk_ratelimit())
312		{
313			printk(KERN_NOTICE "executable not page aligned\n");
314		}
315
316		if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit())
317		{
318			printk(KERN_WARNING 
319			       "fd_offset is not page aligned. Please convert program: %s\n",
320			       bprm->file->f_path.dentry->d_name.name);
321		}
322
323		if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
324			loff_t pos = fd_offset;
325			down_write(&current->mm->mmap_sem);
326			do_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
327			up_write(&current->mm->mmap_sem);
328			bprm->file->f_op->read(bprm->file,
329					(char __user *)N_TXTADDR(ex),
330					ex.a_text+ex.a_data, &pos);
331			flush_icache_range((unsigned long) N_TXTADDR(ex),
332					   (unsigned long) N_TXTADDR(ex) +
333					   ex.a_text+ex.a_data);
334			goto beyond_if;
335		}
336
337		down_write(&current->mm->mmap_sem);
338		error = do_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
339			PROT_READ | PROT_EXEC,
340			MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
341			fd_offset);
342		up_write(&current->mm->mmap_sem);
343
344		if (error != N_TXTADDR(ex)) {
345			send_sig(SIGKILL, current, 0);
346			return error;
347		}
348
349		down_write(&current->mm->mmap_sem);
350 		error = do_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
351				PROT_READ | PROT_WRITE | PROT_EXEC,
352				MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
353				fd_offset + ex.a_text);
354		up_write(&current->mm->mmap_sem);
355		if (error != N_DATADDR(ex)) {
356			send_sig(SIGKILL, current, 0);
357			return error;
358		}
359	}
360beyond_if:
361	set_binfmt(&aout_format);
362
363	retval = set_brk(current->mm->start_brk, current->mm->brk);
364	if (retval < 0) {
365		send_sig(SIGKILL, current, 0);
366		return retval;
367	}
368
369	retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
370	if (retval < 0) { 
371		/* Someone check-me: is this error path enough? */ 
372		send_sig(SIGKILL, current, 0); 
373		return retval;
374	}
375
376	current->mm->start_stack =
377		(unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
378#ifdef __alpha__
379	regs->gp = ex.a_gpvalue;
380#endif
381	start_thread(regs, ex.a_entry, current->mm->start_stack);
382	return 0;
383}
384
385static int load_aout_library(struct file *file)
386{
387	struct inode * inode;
388	unsigned long bss, start_addr, len;
389	unsigned long error;
390	int retval;
391	struct exec ex;
392
393	inode = file->f_path.dentry->d_inode;
394
395	retval = -ENOEXEC;
396	error = kernel_read(file, 0, (char *) &ex, sizeof(ex));
397	if (error != sizeof(ex))
398		goto out;
399
400	/* We come in here for the regular a.out style of shared libraries */
401	if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
402	    N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
403	    i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
404		goto out;
405	}
406
407	/*
408	 * Requires a mmap handler. This prevents people from using a.out
409	 * as part of an exploit attack against /proc-related vulnerabilities.
410	 */
411	if (!file->f_op || !file->f_op->mmap)
412		goto out;
413
414	if (N_FLAGS(ex))
415		goto out;
416
417	/* For  QMAGIC, the starting address is 0x20 into the page.  We mask
418	   this off to get the starting address for the page */
419
420	start_addr =  ex.a_entry & 0xfffff000;
421
422	if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
423		loff_t pos = N_TXTOFF(ex);
424
425		if (printk_ratelimit())
426		{
427			printk(KERN_WARNING 
428			       "N_TXTOFF is not page aligned. Please convert library: %s\n",
429			       file->f_path.dentry->d_name.name);
430		}
431		down_write(&current->mm->mmap_sem);
432		do_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
433		up_write(&current->mm->mmap_sem);
434		
435		file->f_op->read(file, (char __user *)start_addr,
436			ex.a_text + ex.a_data, &pos);
437		flush_icache_range((unsigned long) start_addr,
438				   (unsigned long) start_addr + ex.a_text + ex.a_data);
439
440		retval = 0;
441		goto out;
442	}
443	/* Now use mmap to map the library into memory. */
444	down_write(&current->mm->mmap_sem);
445	error = do_mmap(file, start_addr, ex.a_text + ex.a_data,
446			PROT_READ | PROT_WRITE | PROT_EXEC,
447			MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
448			N_TXTOFF(ex));
449	up_write(&current->mm->mmap_sem);
450	retval = error;
451	if (error != start_addr)
452		goto out;
453
454	len = PAGE_ALIGN(ex.a_text + ex.a_data);
455	bss = ex.a_text + ex.a_data + ex.a_bss;
456	if (bss > len) {
457		down_write(&current->mm->mmap_sem);
458		error = do_brk(start_addr + len, bss - len);
459		up_write(&current->mm->mmap_sem);
460		retval = error;
461		if (error != start_addr + len)
462			goto out;
463	}
464	retval = 0;
465out:
466	return retval;
467}
468
469static int __init init_aout_binfmt(void)
470{
471	return register_binfmt(&aout_format);
472}
473
474static void __exit exit_aout_binfmt(void)
475{
476	unregister_binfmt(&aout_format);
477}
478
479core_initcall(init_aout_binfmt);
480module_exit(exit_aout_binfmt);
481MODULE_LICENSE("GPL");