binfmt_aout.c 10.7 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
/*
 *  linux/fs/binfmt_aout.c
 *
 *  Copyright (C) 1991, 1992, 1996  Linus Torvalds
 */

#include <linux/module.h>

#include <linux/time.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/a.out.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/string.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/stat.h>
#include <linux/fcntl.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/binfmts.h>
#include <linux/personality.h>
#include <linux/init.h>
26
#include <linux/coredump.h>
27
#include <linux/slab.h>
Linus Torvalds's avatar
Linus Torvalds committed
28 29 30

#include <asm/uaccess.h>
#include <asm/cacheflush.h>
31
#include <asm/a.out-core.h>
Linus Torvalds's avatar
Linus Torvalds committed
32

33
static int load_aout_binary(struct linux_binprm *);
Linus Torvalds's avatar
Linus Torvalds committed
34 35
static int load_aout_library(struct file*);

36
#ifdef CONFIG_COREDUMP
Linus Torvalds's avatar
Linus Torvalds committed
37 38 39 40 41 42 43 44 45
/*
 * Routine writes a core dump image in the current directory.
 * Currently only a stub-function.
 *
 * Note that setuid/setgid files won't make a core-dump if the uid/gid
 * changed due to the set[u|g]id. It's enforced by the "current->mm->dumpable"
 * field, which also makes sure the core-dumps won't be recursive if the
 * dumping of the process results in another error..
 */
46
static int aout_core_dump(struct coredump_params *cprm)
Linus Torvalds's avatar
Linus Torvalds committed
47 48 49
{
	mm_segment_t fs;
	int has_dumped = 0;
50 51
	void __user *dump_start;
	int dump_size;
Linus Torvalds's avatar
Linus Torvalds committed
52
	struct user dump;
Al Viro's avatar
Al Viro committed
53
#ifdef __alpha__
54
#       define START_DATA(u)	((void __user *)u.start_data)
Al Viro's avatar
Al Viro committed
55
#else
56 57
#	define START_DATA(u)	((void __user *)((u.u_tsize << PAGE_SHIFT) + \
				 u.start_code))
Linus Torvalds's avatar
Linus Torvalds committed
58
#endif
59
#       define START_STACK(u)   ((void __user *)u.start_stack)
Linus Torvalds's avatar
Linus Torvalds committed
60 61 62 63 64

	fs = get_fs();
	set_fs(KERNEL_DS);
	has_dumped = 1;
       	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);
Linus Torvalds's avatar
Linus Torvalds committed
68 69 70

/* If the size of the dump file exceeds the rlimit, then see what would happen
   if we wrote the stack, but not the data area.  */
71
	if ((dump.u_dsize + dump.u_ssize+1) * PAGE_SIZE > cprm->limit)
Linus Torvalds's avatar
Linus Torvalds committed
72 73 74
		dump.u_dsize = 0;

/* Make sure we have enough room to write the stack and data areas. */
75
	if ((dump.u_ssize + 1) * PAGE_SIZE > cprm->limit)
Linus Torvalds's avatar
Linus Torvalds committed
76 77 78 79
		dump.u_ssize = 0;

/* make sure we actually have a data and stack area to dump */
	set_fs(USER_DS);
80
	if (!access_ok(VERIFY_READ, START_DATA(dump), dump.u_dsize << PAGE_SHIFT))
Linus Torvalds's avatar
Linus Torvalds committed
81
		dump.u_dsize = 0;
82
	if (!access_ok(VERIFY_READ, START_STACK(dump), dump.u_ssize << PAGE_SHIFT))
Linus Torvalds's avatar
Linus Torvalds committed
83 84 85 86
		dump.u_ssize = 0;

	set_fs(KERNEL_DS);
/* struct user */
Al Viro's avatar
Al Viro committed
87
	if (!dump_emit(cprm, &dump, sizeof(dump)))
88
		goto end_coredump;
Linus Torvalds's avatar
Linus Torvalds committed
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;
Linus Torvalds's avatar
Linus Torvalds committed
92 93 94 95 96 97
/* now we start writing out the user space info */
	set_fs(USER_DS);
/* Dump the data area */
	if (dump.u_dsize != 0) {
		dump_start = START_DATA(dump);
		dump_size = dump.u_dsize << PAGE_SHIFT;
Al Viro's avatar
Al Viro committed
98
		if (!dump_emit(cprm, dump_start, dump_size))
99
			goto end_coredump;
Linus Torvalds's avatar
Linus Torvalds committed
100 101 102 103 104
	}
/* Now prepare to dump the stack area */
	if (dump.u_ssize != 0) {
		dump_start = START_STACK(dump);
		dump_size = dump.u_ssize << PAGE_SHIFT;
Al Viro's avatar
Al Viro committed
105
		if (!dump_emit(cprm, dump_start, dump_size))
106
			goto end_coredump;
Linus Torvalds's avatar
Linus Torvalds committed
107 108 109 110 111
	}
end_coredump:
	set_fs(fs);
	return has_dumped;
}
112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129
#else
#define aout_core_dump NULL
#endif

static struct linux_binfmt aout_format = {
	.module		= THIS_MODULE,
	.load_binary	= load_aout_binary,
	.load_shlib	= load_aout_library,
	.core_dump	= aout_core_dump,
	.min_coredump	= PAGE_SIZE
};

#define BAD_ADDR(x)	((unsigned long)(x) >= TASK_SIZE)

static int set_brk(unsigned long start, unsigned long end)
{
	start = PAGE_ALIGN(start);
	end = PAGE_ALIGN(end);
130 131
	if (end > start)
		return vm_brk(start, end - start);
132 133
	return 0;
}
Linus Torvalds's avatar
Linus Torvalds committed
134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154

/*
 * create_aout_tables() parses the env- and arg-strings in new user
 * memory and creates the pointer tables from them, and puts their
 * addresses on the "stack", returning the new stack pointer value.
 */
static unsigned long __user *create_aout_tables(char __user *p, struct linux_binprm * bprm)
{
	char __user * __user *argv;
	char __user * __user *envp;
	unsigned long __user *sp;
	int argc = bprm->argc;
	int envc = bprm->envc;

	sp = (void __user *)((-(unsigned long)sizeof(char *)) & (unsigned long) p);
#ifdef __alpha__
/* whee.. test-programs are so much fun. */
	put_user(0, --sp);
	put_user(0, --sp);
	if (bprm->loader) {
		put_user(0, --sp);
Al Viro's avatar
Al Viro committed
155
		put_user(1003, --sp);
Linus Torvalds's avatar
Linus Torvalds committed
156
		put_user(bprm->loader, --sp);
Al Viro's avatar
Al Viro committed
157
		put_user(1002, --sp);
Linus Torvalds's avatar
Linus Torvalds committed
158 159
	}
	put_user(bprm->exec, --sp);
Al Viro's avatar
Al Viro committed
160
	put_user(1001, --sp);
Linus Torvalds's avatar
Linus Torvalds committed
161 162 163 164 165
#endif
	sp -= envc+1;
	envp = (char __user * __user *) sp;
	sp -= argc+1;
	argv = (char __user * __user *) sp;
Al Viro's avatar
Al Viro committed
166
#ifndef __alpha__
Linus Torvalds's avatar
Linus Torvalds committed
167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197
	put_user((unsigned long) envp,--sp);
	put_user((unsigned long) argv,--sp);
#endif
	put_user(argc,--sp);
	current->mm->arg_start = (unsigned long) p;
	while (argc-->0) {
		char c;
		put_user(p,argv++);
		do {
			get_user(c,p++);
		} while (c);
	}
	put_user(NULL,argv);
	current->mm->arg_end = current->mm->env_start = (unsigned long) p;
	while (envc-->0) {
		char c;
		put_user(p,envp++);
		do {
			get_user(c,p++);
		} while (c);
	}
	put_user(NULL,envp);
	current->mm->env_end = (unsigned long) p;
	return sp;
}

/*
 * These are the functions used to load a.out style executables and shared
 * libraries.  There is no binary dependent code anywhere else.
 */

198
static int load_aout_binary(struct linux_binprm * bprm)
Linus Torvalds's avatar
Linus Torvalds committed
199
{
200
	struct pt_regs *regs = current_pt_regs();
Linus Torvalds's avatar
Linus Torvalds committed
201 202 203 204 205 206 207 208 209 210
	struct exec ex;
	unsigned long error;
	unsigned long fd_offset;
	unsigned long rlim;
	int retval;

	ex = *((struct exec *) bprm->buf);		/* exec-header */
	if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
	     N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
	    N_TRSIZE(ex) || N_DRSIZE(ex) ||
Al Viro's avatar
Al Viro committed
211
	    i_size_read(file_inode(bprm->file)) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
Linus Torvalds's avatar
Linus Torvalds committed
212 213 214
		return -ENOEXEC;
	}

215 216 217 218
	/*
	 * Requires a mmap handler. This prevents people from using a.out
	 * as part of an exploit attack against /proc-related vulnerabilities.
	 */
Al Viro's avatar
Al Viro committed
219
	if (!bprm->file->f_op->mmap)
220 221
		return -ENOEXEC;

Linus Torvalds's avatar
Linus Torvalds committed
222 223 224 225 226 227
	fd_offset = N_TXTOFF(ex);

	/* Check initial limits. This avoids letting people circumvent
	 * size limits imposed on them by creating programs with large
	 * arrays in the data or bss.
	 */
Jiri Slaby's avatar
Jiri Slaby committed
228
	rlim = rlimit(RLIMIT_DATA);
Linus Torvalds's avatar
Linus Torvalds committed
229 230 231 232 233 234 235 236 237 238 239
	if (rlim >= RLIM_INFINITY)
		rlim = ~0;
	if (ex.a_data + ex.a_bss > rlim)
		return -ENOMEM;

	/* Flush all traces of the currently running executable */
	retval = flush_old_exec(bprm);
	if (retval)
		return retval;

	/* OK, This is the point of no return */
Al Viro's avatar
Al Viro committed
240
#ifdef __alpha__
Linus Torvalds's avatar
Linus Torvalds committed
241 242 243 244
	SET_AOUT_PERSONALITY(bprm, ex);
#else
	set_personality(PER_LINUX);
#endif
245
	setup_new_exec(bprm);
Linus Torvalds's avatar
Linus Torvalds committed
246 247 248 249 250 251 252 253

	current->mm->end_code = ex.a_text +
		(current->mm->start_code = N_TXTADDR(ex));
	current->mm->end_data = ex.a_data +
		(current->mm->start_data = N_DATADDR(ex));
	current->mm->brk = ex.a_bss +
		(current->mm->start_brk = N_BSSADDR(ex));

254
	retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
255
	if (retval < 0)
256 257
		return retval;

258
	install_exec_creds(bprm);
Linus Torvalds's avatar
Linus Torvalds committed
259 260 261 262 263 264 265

	if (N_MAGIC(ex) == OMAGIC) {
		unsigned long text_addr, map_size;
		loff_t pos;

		text_addr = N_TXTADDR(ex);

266
#ifdef __alpha__
Linus Torvalds's avatar
Linus Torvalds committed
267 268 269 270 271 272
		pos = fd_offset;
		map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
#else
		pos = 32;
		map_size = ex.a_text+ex.a_data;
#endif
273
		error = vm_brk(text_addr & PAGE_MASK, map_size);
274
		if (error)
Linus Torvalds's avatar
Linus Torvalds committed
275 276
			return error;

Al Viro's avatar
Al Viro committed
277 278
		error = read_code(bprm->file, text_addr, pos,
				  ex.a_text+ex.a_data);
279
		if ((signed long)error < 0)
Linus Torvalds's avatar
Linus Torvalds committed
280 281 282
			return error;
	} else {
		if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
283
		    (N_MAGIC(ex) != NMAGIC) && printk_ratelimit())
Linus Torvalds's avatar
Linus Torvalds committed
284 285 286 287
		{
			printk(KERN_NOTICE "executable not page aligned\n");
		}

288
		if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit())
Linus Torvalds's avatar
Linus Torvalds committed
289 290
		{
			printk(KERN_WARNING 
Al Viro's avatar
Al Viro committed
291 292
			       "fd_offset is not page aligned. Please convert program: %pD\n",
			       bprm->file);
Linus Torvalds's avatar
Linus Torvalds committed
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)
298 299
				return error;

Al Viro's avatar
Al Viro committed
300 301
			read_code(bprm->file, N_TXTADDR(ex), fd_offset,
				  ex.a_text + ex.a_data);
Linus Torvalds's avatar
Linus Torvalds committed
302 303 304
			goto beyond_if;
		}

305
		error = vm_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
Linus Torvalds's avatar
Linus Torvalds committed
306 307 308 309
			PROT_READ | PROT_EXEC,
			MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
			fd_offset);

310
		if (error != N_TXTADDR(ex))
Linus Torvalds's avatar
Linus Torvalds committed
311 312
			return error;

313
		error = vm_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
Linus Torvalds's avatar
Linus Torvalds committed
314 315 316
				PROT_READ | PROT_WRITE | PROT_EXEC,
				MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
				fd_offset + ex.a_text);
317
		if (error != N_DATADDR(ex))
Linus Torvalds's avatar
Linus Torvalds committed
318 319 320 321 322 323
			return error;
	}
beyond_if:
	set_binfmt(&aout_format);

	retval = set_brk(current->mm->start_brk, current->mm->brk);
324
	if (retval < 0)
Linus Torvalds's avatar
Linus Torvalds committed
325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343
		return retval;

	current->mm->start_stack =
		(unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
#ifdef __alpha__
	regs->gp = ex.a_gpvalue;
#endif
	start_thread(regs, ex.a_entry, current->mm->start_stack);
	return 0;
}

static int load_aout_library(struct file *file)
{
	struct inode * inode;
	unsigned long bss, start_addr, len;
	unsigned long error;
	int retval;
	struct exec ex;

Al Viro's avatar
Al Viro committed
344
	inode = file_inode(file);
Linus Torvalds's avatar
Linus Torvalds committed
345 346 347 348 349 350 351 352 353 354 355 356 357

	retval = -ENOEXEC;
	error = kernel_read(file, 0, (char *) &ex, sizeof(ex));
	if (error != sizeof(ex))
		goto out;

	/* We come in here for the regular a.out style of shared libraries */
	if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
	    N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
	    i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
		goto out;
	}

358 359 360 361
	/*
	 * Requires a mmap handler. This prevents people from using a.out
	 * as part of an exploit attack against /proc-related vulnerabilities.
	 */
Al Viro's avatar
Al Viro committed
362
	if (!file->f_op->mmap)
363 364
		goto out;

Linus Torvalds's avatar
Linus Torvalds committed
365 366 367 368 369 370 371 372 373
	if (N_FLAGS(ex))
		goto out;

	/* For  QMAGIC, the starting address is 0x20 into the page.  We mask
	   this off to get the starting address for the page */

	start_addr =  ex.a_entry & 0xfffff000;

	if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
374
		if (printk_ratelimit())
Linus Torvalds's avatar
Linus Torvalds committed
375 376
		{
			printk(KERN_WARNING 
Al Viro's avatar
Al Viro committed
377 378
			       "N_TXTOFF is not page aligned. Please convert library: %pD\n",
			       file);
Linus Torvalds's avatar
Linus Torvalds committed
379
		}
380
		retval = vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
381
		if (retval)
382 383
			goto out;

Al Viro's avatar
Al Viro committed
384 385
		read_code(file, start_addr, N_TXTOFF(ex),
			  ex.a_text + ex.a_data);
Linus Torvalds's avatar
Linus Torvalds committed
386 387 388 389
		retval = 0;
		goto out;
	}
	/* Now use mmap to map the library into memory. */
390
	error = vm_mmap(file, start_addr, ex.a_text + ex.a_data,
Linus Torvalds's avatar
Linus Torvalds committed
391 392 393 394 395 396 397 398 399 400
			PROT_READ | PROT_WRITE | PROT_EXEC,
			MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
			N_TXTOFF(ex));
	retval = error;
	if (error != start_addr)
		goto out;

	len = PAGE_ALIGN(ex.a_text + ex.a_data);
	bss = ex.a_text + ex.a_data + ex.a_bss;
	if (bss > len) {
401 402
		retval = vm_brk(start_addr + len, bss - len);
		if (retval)
Linus Torvalds's avatar
Linus Torvalds committed
403 404 405 406 407 408 409 410 411
			goto out;
	}
	retval = 0;
out:
	return retval;
}

static int __init init_aout_binfmt(void)
{
Al Viro's avatar
Al Viro committed
412 413
	register_binfmt(&aout_format);
	return 0;
Linus Torvalds's avatar
Linus Torvalds committed
414 415 416 417 418 419 420 421 422 423
}

static void __exit exit_aout_binfmt(void)
{
	unregister_binfmt(&aout_format);
}

core_initcall(init_aout_binfmt);
module_exit(exit_aout_binfmt);
MODULE_LICENSE("GPL");