exec.c 40.4 KB
Newer Older
L
Linus Torvalds 已提交
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 26
/*
 *  linux/fs/exec.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

/*
 * #!-checking implemented by tytso.
 */
/*
 * Demand-loading implemented 01.12.91 - no need to read anything but
 * the header into memory. The inode of the executable is put into
 * "current->executable", and page faults do the actual loading. Clean.
 *
 * Once more I can proudly say that linux stood up to being changed: it
 * was less than 2 hours work to get demand-loading completely implemented.
 *
 * Demand loading changed July 1993 by Eric Youngdale.   Use mmap instead,
 * current->executable is only used by the procfs.  This allows a dispatch
 * table to check for several different types  of binary formats.  We keep
 * trying until we recognize the file or we run out of supported binary
 * formats. 
 */

#include <linux/slab.h>
#include <linux/file.h>
A
Al Viro 已提交
27
#include <linux/fdtable.h>
L
Linus Torvalds 已提交
28 29 30 31 32
#include <linux/mman.h>
#include <linux/a.out.h>
#include <linux/stat.h>
#include <linux/fcntl.h>
#include <linux/smp_lock.h>
33
#include <linux/string.h>
L
Linus Torvalds 已提交
34 35 36 37 38 39 40 41 42
#include <linux/init.h>
#include <linux/pagemap.h>
#include <linux/highmem.h>
#include <linux/spinlock.h>
#include <linux/key.h>
#include <linux/personality.h>
#include <linux/binfmts.h>
#include <linux/swap.h>
#include <linux/utsname.h>
43
#include <linux/pid_namespace.h>
L
Linus Torvalds 已提交
44 45 46 47 48 49 50 51
#include <linux/module.h>
#include <linux/namei.h>
#include <linux/proc_fs.h>
#include <linux/ptrace.h>
#include <linux/mount.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/rmap.h>
52
#include <linux/tsacct_kern.h>
M
Matt Helsley 已提交
53
#include <linux/cn_proc.h>
A
Al Viro 已提交
54
#include <linux/audit.h>
L
Linus Torvalds 已提交
55 56 57

#include <asm/uaccess.h>
#include <asm/mmu_context.h>
58
#include <asm/tlb.h>
L
Linus Torvalds 已提交
59 60 61 62 63 64

#ifdef CONFIG_KMOD
#include <linux/kmod.h>
#endif

int core_uses_pid;
65
char core_pattern[CORENAME_MAX_SIZE] = "core";
A
Alan Cox 已提交
66 67
int suid_dumpable = 0;

L
Linus Torvalds 已提交
68 69
/* The maximal length of core_pattern is also specified in sysctl.c */

A
Alexey Dobriyan 已提交
70
static LIST_HEAD(formats);
L
Linus Torvalds 已提交
71 72 73 74 75 76 77
static DEFINE_RWLOCK(binfmt_lock);

int register_binfmt(struct linux_binfmt * fmt)
{
	if (!fmt)
		return -EINVAL;
	write_lock(&binfmt_lock);
A
Alexey Dobriyan 已提交
78
	list_add(&fmt->lh, &formats);
L
Linus Torvalds 已提交
79 80 81 82 83 84
	write_unlock(&binfmt_lock);
	return 0;	
}

EXPORT_SYMBOL(register_binfmt);

85
void unregister_binfmt(struct linux_binfmt * fmt)
L
Linus Torvalds 已提交
86 87
{
	write_lock(&binfmt_lock);
A
Alexey Dobriyan 已提交
88
	list_del(&fmt->lh);
L
Linus Torvalds 已提交
89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110
	write_unlock(&binfmt_lock);
}

EXPORT_SYMBOL(unregister_binfmt);

static inline void put_binfmt(struct linux_binfmt * fmt)
{
	module_put(fmt->module);
}

/*
 * Note that a shared library must be both readable and executable due to
 * security reasons.
 *
 * Also note that we take the address to load from from the file itself.
 */
asmlinkage long sys_uselib(const char __user * library)
{
	struct file * file;
	struct nameidata nd;
	int error;

111
	error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
L
Linus Torvalds 已提交
112 113 114 115
	if (error)
		goto out;

	error = -EINVAL;
116
	if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
L
Linus Torvalds 已提交
117 118
		goto exit;

119
	error = vfs_permission(&nd, MAY_READ | MAY_EXEC);
L
Linus Torvalds 已提交
120 121 122
	if (error)
		goto exit;

A
Andi Kleen 已提交
123
	file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE);
L
Linus Torvalds 已提交
124 125 126 127 128 129 130 131 132
	error = PTR_ERR(file);
	if (IS_ERR(file))
		goto out;

	error = -ENOEXEC;
	if(file->f_op) {
		struct linux_binfmt * fmt;

		read_lock(&binfmt_lock);
A
Alexey Dobriyan 已提交
133
		list_for_each_entry(fmt, &formats, lh) {
L
Linus Torvalds 已提交
134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150
			if (!fmt->load_shlib)
				continue;
			if (!try_module_get(fmt->module))
				continue;
			read_unlock(&binfmt_lock);
			error = fmt->load_shlib(file);
			read_lock(&binfmt_lock);
			put_binfmt(fmt);
			if (error != -ENOEXEC)
				break;
		}
		read_unlock(&binfmt_lock);
	}
	fput(file);
out:
  	return error;
exit:
151
	release_open_intent(&nd);
J
Jan Blunck 已提交
152
	path_put(&nd.path);
L
Linus Torvalds 已提交
153 154 155
	goto out;
}

156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177
#ifdef CONFIG_MMU

static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
		int write)
{
	struct page *page;
	int ret;

#ifdef CONFIG_STACK_GROWSUP
	if (write) {
		ret = expand_stack_downwards(bprm->vma, pos);
		if (ret < 0)
			return NULL;
	}
#endif
	ret = get_user_pages(current, bprm->mm, pos,
			1, write, 1, &page, NULL);
	if (ret <= 0)
		return NULL;

	if (write) {
		unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
178 179 180 181 182 183 184 185
		struct rlimit *rlim;

		/*
		 * We've historically supported up to 32 pages (ARG_MAX)
		 * of argument strings even with small stacks
		 */
		if (size <= ARG_MAX)
			return page;
186 187 188 189 190 191 192 193

		/*
		 * Limit to 1/4-th the stack size for the argv+env strings.
		 * This ensures that:
		 *  - the remaining binfmt code will not run out of stack space,
		 *  - the program will have a reasonable amount of stack left
		 *    to work from.
		 */
194
		rlim = current->signal->rlim;
195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245
		if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
			put_page(page);
			return NULL;
		}
	}

	return page;
}

static void put_arg_page(struct page *page)
{
	put_page(page);
}

static void free_arg_page(struct linux_binprm *bprm, int i)
{
}

static void free_arg_pages(struct linux_binprm *bprm)
{
}

static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
		struct page *page)
{
	flush_cache_page(bprm->vma, pos, page_to_pfn(page));
}

static int __bprm_mm_init(struct linux_binprm *bprm)
{
	int err = -ENOMEM;
	struct vm_area_struct *vma = NULL;
	struct mm_struct *mm = bprm->mm;

	bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
	if (!vma)
		goto err;

	down_write(&mm->mmap_sem);
	vma->vm_mm = mm;

	/*
	 * Place the stack at the largest stack address the architecture
	 * supports. Later, we'll move this to an appropriate place. We don't
	 * use STACK_TOP because that can depend on attributes which aren't
	 * configured yet.
	 */
	vma->vm_end = STACK_TOP_MAX;
	vma->vm_start = vma->vm_end - PAGE_SIZE;

	vma->vm_flags = VM_STACK_FLAGS;
246
	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364
	err = insert_vm_struct(mm, vma);
	if (err) {
		up_write(&mm->mmap_sem);
		goto err;
	}

	mm->stack_vm = mm->total_vm = 1;
	up_write(&mm->mmap_sem);

	bprm->p = vma->vm_end - sizeof(void *);

	return 0;

err:
	if (vma) {
		bprm->vma = NULL;
		kmem_cache_free(vm_area_cachep, vma);
	}

	return err;
}

static bool valid_arg_len(struct linux_binprm *bprm, long len)
{
	return len <= MAX_ARG_STRLEN;
}

#else

static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
		int write)
{
	struct page *page;

	page = bprm->page[pos / PAGE_SIZE];
	if (!page && write) {
		page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
		if (!page)
			return NULL;
		bprm->page[pos / PAGE_SIZE] = page;
	}

	return page;
}

static void put_arg_page(struct page *page)
{
}

static void free_arg_page(struct linux_binprm *bprm, int i)
{
	if (bprm->page[i]) {
		__free_page(bprm->page[i]);
		bprm->page[i] = NULL;
	}
}

static void free_arg_pages(struct linux_binprm *bprm)
{
	int i;

	for (i = 0; i < MAX_ARG_PAGES; i++)
		free_arg_page(bprm, i);
}

static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
		struct page *page)
{
}

static int __bprm_mm_init(struct linux_binprm *bprm)
{
	bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
	return 0;
}

static bool valid_arg_len(struct linux_binprm *bprm, long len)
{
	return len <= bprm->p;
}

#endif /* CONFIG_MMU */

/*
 * Create a new mm_struct and populate it with a temporary stack
 * vm_area_struct.  We don't have enough context at this point to set the stack
 * flags, permissions, and offset, so we use temporary values.  We'll update
 * them later in setup_arg_pages().
 */
int bprm_mm_init(struct linux_binprm *bprm)
{
	int err;
	struct mm_struct *mm = NULL;

	bprm->mm = mm = mm_alloc();
	err = -ENOMEM;
	if (!mm)
		goto err;

	err = init_new_context(current, mm);
	if (err)
		goto err;

	err = __bprm_mm_init(bprm);
	if (err)
		goto err;

	return 0;

err:
	if (mm) {
		bprm->mm = NULL;
		mmdrop(mm);
	}

	return err;
}

L
Linus Torvalds 已提交
365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389
/*
 * count() counts the number of strings in array ARGV.
 */
static int count(char __user * __user * argv, int max)
{
	int i = 0;

	if (argv != NULL) {
		for (;;) {
			char __user * p;

			if (get_user(p, argv))
				return -EFAULT;
			if (!p)
				break;
			argv++;
			if(++i > max)
				return -E2BIG;
			cond_resched();
		}
	}
	return i;
}

/*
390 391 392
 * 'copy_strings()' copies argument/environment strings from the old
 * processes's memory to the new process's stack.  The call to get_user_pages()
 * ensures the destination page is created and not swapped out.
L
Linus Torvalds 已提交
393
 */
A
Adrian Bunk 已提交
394 395
static int copy_strings(int argc, char __user * __user * argv,
			struct linux_binprm *bprm)
L
Linus Torvalds 已提交
396 397 398
{
	struct page *kmapped_page = NULL;
	char *kaddr = NULL;
399
	unsigned long kpos = 0;
L
Linus Torvalds 已提交
400 401 402 403 404 405 406 407
	int ret;

	while (argc-- > 0) {
		char __user *str;
		int len;
		unsigned long pos;

		if (get_user(str, argv+argc) ||
408
				!(len = strnlen_user(str, MAX_ARG_STRLEN))) {
L
Linus Torvalds 已提交
409 410 411 412
			ret = -EFAULT;
			goto out;
		}

413
		if (!valid_arg_len(bprm, len)) {
L
Linus Torvalds 已提交
414 415 416 417
			ret = -E2BIG;
			goto out;
		}

418
		/* We're going to work our way backwords. */
L
Linus Torvalds 已提交
419
		pos = bprm->p;
420 421
		str += len;
		bprm->p -= len;
L
Linus Torvalds 已提交
422 423 424 425 426

		while (len > 0) {
			int offset, bytes_to_copy;

			offset = pos % PAGE_SIZE;
427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442
			if (offset == 0)
				offset = PAGE_SIZE;

			bytes_to_copy = offset;
			if (bytes_to_copy > len)
				bytes_to_copy = len;

			offset -= bytes_to_copy;
			pos -= bytes_to_copy;
			str -= bytes_to_copy;
			len -= bytes_to_copy;

			if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
				struct page *page;

				page = get_arg_page(bprm, pos, 1);
L
Linus Torvalds 已提交
443
				if (!page) {
444
					ret = -E2BIG;
L
Linus Torvalds 已提交
445 446 447
					goto out;
				}

448 449
				if (kmapped_page) {
					flush_kernel_dcache_page(kmapped_page);
L
Linus Torvalds 已提交
450
					kunmap(kmapped_page);
451 452
					put_arg_page(kmapped_page);
				}
L
Linus Torvalds 已提交
453 454
				kmapped_page = page;
				kaddr = kmap(kmapped_page);
455 456
				kpos = pos & PAGE_MASK;
				flush_arg_page(bprm, kpos, kmapped_page);
L
Linus Torvalds 已提交
457
			}
458
			if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
L
Linus Torvalds 已提交
459 460 461 462 463 464 465
				ret = -EFAULT;
				goto out;
			}
		}
	}
	ret = 0;
out:
466 467
	if (kmapped_page) {
		flush_kernel_dcache_page(kmapped_page);
L
Linus Torvalds 已提交
468
		kunmap(kmapped_page);
469 470
		put_arg_page(kmapped_page);
	}
L
Linus Torvalds 已提交
471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488
	return ret;
}

/*
 * Like copy_strings, but get argv and its values from kernel memory.
 */
int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
{
	int r;
	mm_segment_t oldfs = get_fs();
	set_fs(KERNEL_DS);
	r = copy_strings(argc, (char __user * __user *)argv, bprm);
	set_fs(oldfs);
	return r;
}
EXPORT_SYMBOL(copy_strings_kernel);

#ifdef CONFIG_MMU
489

L
Linus Torvalds 已提交
490
/*
491 492 493
 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 * the binfmt code determines where the new stack should reside, we shift it to
 * its final location.  The process proceeds as follows:
L
Linus Torvalds 已提交
494
 *
495 496 497 498 499 500
 * 1) Use shift to calculate the new vma endpoints.
 * 2) Extend vma to cover both the old and new ranges.  This ensures the
 *    arguments passed to subsequent functions are consistent.
 * 3) Move vma's page tables to the new range.
 * 4) Free up any cleared pgd range.
 * 5) Shrink the vma to cover only the new range.
L
Linus Torvalds 已提交
501
 */
502
static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
L
Linus Torvalds 已提交
503 504
{
	struct mm_struct *mm = vma->vm_mm;
505 506 507 508 509 510
	unsigned long old_start = vma->vm_start;
	unsigned long old_end = vma->vm_end;
	unsigned long length = old_end - old_start;
	unsigned long new_start = old_start - shift;
	unsigned long new_end = old_end - shift;
	struct mmu_gather *tlb;
L
Linus Torvalds 已提交
511

512
	BUG_ON(new_start > new_end);
L
Linus Torvalds 已提交
513

514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550
	/*
	 * ensure there are no vmas between where we want to go
	 * and where we are
	 */
	if (vma != find_vma(mm, new_start))
		return -EFAULT;

	/*
	 * cover the whole range: [new_start, old_end)
	 */
	vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);

	/*
	 * move the page tables downwards, on failure we rely on
	 * process cleanup to remove whatever mess we made.
	 */
	if (length != move_page_tables(vma, old_start,
				       vma, new_start, length))
		return -ENOMEM;

	lru_add_drain();
	tlb = tlb_gather_mmu(mm, 0);
	if (new_end > old_start) {
		/*
		 * when the old and new regions overlap clear from new_end.
		 */
		free_pgd_range(&tlb, new_end, old_end, new_end,
			vma->vm_next ? vma->vm_next->vm_start : 0);
	} else {
		/*
		 * otherwise, clean from old_start; this is done to not touch
		 * the address space in [new_end, old_start) some architectures
		 * have constraints on va-space that make this illegal (IA64) -
		 * for the others its just a little faster.
		 */
		free_pgd_range(&tlb, old_start, old_end, new_end,
			vma->vm_next ? vma->vm_next->vm_start : 0);
L
Linus Torvalds 已提交
551
	}
552 553 554 555 556 557 558 559
	tlb_finish_mmu(tlb, new_end, old_end);

	/*
	 * shrink the vma to just the new range.
	 */
	vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);

	return 0;
L
Linus Torvalds 已提交
560 561 562 563
}

#define EXTRA_STACK_VM_PAGES	20	/* random */

564 565 566 567
/*
 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 * the stack is optionally relocated, and some extra space is added.
 */
L
Linus Torvalds 已提交
568 569 570 571
int setup_arg_pages(struct linux_binprm *bprm,
		    unsigned long stack_top,
		    int executable_stack)
{
572 573
	unsigned long ret;
	unsigned long stack_shift;
L
Linus Torvalds 已提交
574
	struct mm_struct *mm = current->mm;
575 576 577 578
	struct vm_area_struct *vma = bprm->vma;
	struct vm_area_struct *prev = NULL;
	unsigned long vm_flags;
	unsigned long stack_base;
L
Linus Torvalds 已提交
579 580 581 582 583 584 585

#ifdef CONFIG_STACK_GROWSUP
	/* Limit stack size to 1GB */
	stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
	if (stack_base > (1 << 30))
		stack_base = 1 << 30;

586 587 588
	/* Make sure we didn't let the argument array grow too large. */
	if (vma->vm_end - vma->vm_start > stack_base)
		return -ENOMEM;
L
Linus Torvalds 已提交
589

590
	stack_base = PAGE_ALIGN(stack_top - stack_base);
L
Linus Torvalds 已提交
591

592 593 594
	stack_shift = vma->vm_start - stack_base;
	mm->arg_start = bprm->p - stack_shift;
	bprm->p = vma->vm_end - stack_shift;
L
Linus Torvalds 已提交
595
#else
596 597 598 599 600
	stack_top = arch_align_stack(stack_top);
	stack_top = PAGE_ALIGN(stack_top);
	stack_shift = vma->vm_end - stack_top;

	bprm->p -= stack_shift;
L
Linus Torvalds 已提交
601 602 603 604
	mm->arg_start = bprm->p;
#endif

	if (bprm->loader)
605 606
		bprm->loader -= stack_shift;
	bprm->exec -= stack_shift;
L
Linus Torvalds 已提交
607 608

	down_write(&mm->mmap_sem);
609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631
	vm_flags = vma->vm_flags;

	/*
	 * Adjust stack execute permissions; explicitly enable for
	 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
	 * (arch default) otherwise.
	 */
	if (unlikely(executable_stack == EXSTACK_ENABLE_X))
		vm_flags |= VM_EXEC;
	else if (executable_stack == EXSTACK_DISABLE_X)
		vm_flags &= ~VM_EXEC;
	vm_flags |= mm->def_flags;

	ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
			vm_flags);
	if (ret)
		goto out_unlock;
	BUG_ON(prev != vma);

	/* Move stack pages down in memory. */
	if (stack_shift) {
		ret = shift_arg_pages(vma, stack_shift);
		if (ret) {
L
Linus Torvalds 已提交
632 633 634 635 636
			up_write(&mm->mmap_sem);
			return ret;
		}
	}

637 638 639 640 641 642 643 644 645 646
#ifdef CONFIG_STACK_GROWSUP
	stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
#else
	stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
#endif
	ret = expand_stack(vma, stack_base);
	if (ret)
		ret = -EFAULT;

out_unlock:
L
Linus Torvalds 已提交
647 648 649 650 651 652 653 654 655 656 657 658 659
	up_write(&mm->mmap_sem);
	return 0;
}
EXPORT_SYMBOL(setup_arg_pages);

#endif /* CONFIG_MMU */

struct file *open_exec(const char *name)
{
	struct nameidata nd;
	int err;
	struct file *file;

660
	err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
L
Linus Torvalds 已提交
661 662 663
	file = ERR_PTR(err);

	if (!err) {
664
		struct inode *inode = nd.path.dentry->d_inode;
L
Linus Torvalds 已提交
665
		file = ERR_PTR(-EACCES);
666
		if (S_ISREG(inode->i_mode)) {
667
			int err = vfs_permission(&nd, MAY_EXEC);
L
Linus Torvalds 已提交
668 669
			file = ERR_PTR(err);
			if (!err) {
A
Andi Kleen 已提交
670 671
				file = nameidata_to_filp(&nd,
							O_RDONLY|O_LARGEFILE);
L
Linus Torvalds 已提交
672 673 674 675 676 677 678 679 680 681 682
				if (!IS_ERR(file)) {
					err = deny_write_access(file);
					if (err) {
						fput(file);
						file = ERR_PTR(err);
					}
				}
out:
				return file;
			}
		}
683
		release_open_intent(&nd);
J
Jan Blunck 已提交
684
		path_put(&nd.path);
L
Linus Torvalds 已提交
685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738
	}
	goto out;
}

EXPORT_SYMBOL(open_exec);

int kernel_read(struct file *file, unsigned long offset,
	char *addr, unsigned long count)
{
	mm_segment_t old_fs;
	loff_t pos = offset;
	int result;

	old_fs = get_fs();
	set_fs(get_ds());
	/* The cast to a user pointer is valid due to the set_fs() */
	result = vfs_read(file, (void __user *)addr, count, &pos);
	set_fs(old_fs);
	return result;
}

EXPORT_SYMBOL(kernel_read);

static int exec_mmap(struct mm_struct *mm)
{
	struct task_struct *tsk;
	struct mm_struct * old_mm, *active_mm;

	/* Notify parent that we're no longer interested in the old VM */
	tsk = current;
	old_mm = current->mm;
	mm_release(tsk, old_mm);

	if (old_mm) {
		/*
		 * Make sure that if there is a core dump in progress
		 * for the old mm, we get out and die instead of going
		 * through with the exec.  We must hold mmap_sem around
		 * checking core_waiters and changing tsk->mm.  The
		 * core-inducing thread will increment core_waiters for
		 * each thread whose ->mm == old_mm.
		 */
		down_read(&old_mm->mmap_sem);
		if (unlikely(old_mm->core_waiters)) {
			up_read(&old_mm->mmap_sem);
			return -EINTR;
		}
	}
	task_lock(tsk);
	active_mm = tsk->active_mm;
	tsk->mm = mm;
	tsk->active_mm = mm;
	activate_mm(active_mm, mm);
	task_unlock(tsk);
739
	mm_update_next_owner(mm);
L
Linus Torvalds 已提交
740 741 742
	arch_pick_mmap_layout(mm);
	if (old_mm) {
		up_read(&old_mm->mmap_sem);
743
		BUG_ON(active_mm != old_mm);
L
Linus Torvalds 已提交
744 745 746 747 748 749 750 751 752 753 754 755 756
		mmput(old_mm);
		return 0;
	}
	mmdrop(active_mm);
	return 0;
}

/*
 * This function makes sure the current process has its own signal table,
 * so that flush_signal_handlers can later reset the handlers without
 * disturbing other processes.  (Other processes might share the signal
 * table via the CLONE_SIGHAND option to clone().)
 */
757
static int de_thread(struct task_struct *tsk)
L
Linus Torvalds 已提交
758 759
{
	struct signal_struct *sig = tsk->signal;
760
	struct sighand_struct *oldsighand = tsk->sighand;
L
Linus Torvalds 已提交
761
	spinlock_t *lock = &oldsighand->siglock;
762
	struct task_struct *leader = NULL;
L
Linus Torvalds 已提交
763 764
	int count;

765
	if (thread_group_empty(tsk))
L
Linus Torvalds 已提交
766 767 768 769 770 771
		goto no_thread_group;

	/*
	 * Kill all other threads in the thread group.
	 */
	spin_lock_irq(lock);
772
	if (signal_group_exit(sig)) {
L
Linus Torvalds 已提交
773 774 775 776 777 778 779
		/*
		 * Another group action in progress, just
		 * return so that the signal is processed.
		 */
		spin_unlock_irq(lock);
		return -EAGAIN;
	}
780
	sig->group_exit_task = tsk;
781
	zap_other_threads(tsk);
L
Linus Torvalds 已提交
782

783 784
	/* Account for the thread group leader hanging around: */
	count = thread_group_leader(tsk) ? 1 : 2;
785
	sig->notify_count = count;
L
Linus Torvalds 已提交
786 787 788 789 790 791 792 793 794 795 796 797 798
	while (atomic_read(&sig->count) > count) {
		__set_current_state(TASK_UNINTERRUPTIBLE);
		spin_unlock_irq(lock);
		schedule();
		spin_lock_irq(lock);
	}
	spin_unlock_irq(lock);

	/*
	 * At this point all other threads have exited, all we have to
	 * do is to wait for the thread group leader to become inactive,
	 * and to assume its PID:
	 */
799 800
	if (!thread_group_leader(tsk)) {
		leader = tsk->group_leader;
801

802
		sig->notify_count = -1;	/* for exit_notify() */
803 804 805 806 807 808 809 810
		for (;;) {
			write_lock_irq(&tasklist_lock);
			if (likely(leader->exit_state))
				break;
			__set_current_state(TASK_UNINTERRUPTIBLE);
			write_unlock_irq(&tasklist_lock);
			schedule();
		}
L
Linus Torvalds 已提交
811

812 813
		if (unlikely(task_child_reaper(tsk) == leader))
			task_active_pid_ns(tsk)->child_reaper = tsk;
814 815 816 817 818 819 820 821 822 823
		/*
		 * The only record we have of the real-time age of a
		 * process, regardless of execs it's done, is start_time.
		 * All the past CPU time is accumulated in signal_struct
		 * from sister threads now dead.  But in this non-leader
		 * exec, nothing survives from the original leader thread,
		 * whose birth marks the true age of this process now.
		 * When we take on its identity by switching to its PID, we
		 * also take its birthdate (always earlier than our own).
		 */
824
		tsk->start_time = leader->start_time;
825

826 827
		BUG_ON(!same_thread_group(leader, tsk));
		BUG_ON(has_group_leader_pid(tsk));
L
Linus Torvalds 已提交
828 829 830 831 832 833
		/*
		 * An exec() starts a new thread group with the
		 * TGID of the previous thread group. Rehash the
		 * two threads with a switched PID, and release
		 * the former thread group leader:
		 */
834 835

		/* Become a process group leader with the old leader's pid.
836 837
		 * The old leader becomes a thread of the this thread group.
		 * Note: The old leader also uses this pid until release_task
838 839
		 *       is called.  Odd but simple and correct.
		 */
840 841
		detach_pid(tsk, PIDTYPE_PID);
		tsk->pid = leader->pid;
842
		attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
843 844 845
		transfer_pid(leader, tsk, PIDTYPE_PGID);
		transfer_pid(leader, tsk, PIDTYPE_SID);
		list_replace_rcu(&leader->tasks, &tsk->tasks);
L
Linus Torvalds 已提交
846

847 848
		tsk->group_leader = tsk;
		leader->group_leader = tsk;
849

850
		tsk->exit_signal = SIGCHLD;
851 852 853

		BUG_ON(leader->exit_state != EXIT_ZOMBIE);
		leader->exit_state = EXIT_DEAD;
L
Linus Torvalds 已提交
854 855

		write_unlock_irq(&tasklist_lock);
856
	}
L
Linus Torvalds 已提交
857

858 859
	sig->group_exit_task = NULL;
	sig->notify_count = 0;
L
Linus Torvalds 已提交
860 861 862

no_thread_group:
	exit_itimers(sig);
863 864 865
	if (leader)
		release_task(leader);

866 867
	if (atomic_read(&oldsighand->count) != 1) {
		struct sighand_struct *newsighand;
L
Linus Torvalds 已提交
868
		/*
869 870
		 * This ->sighand is shared with the CLONE_SIGHAND
		 * but not CLONE_THREAD task, switch to the new one.
L
Linus Torvalds 已提交
871
		 */
872 873 874 875
		newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
		if (!newsighand)
			return -ENOMEM;

L
Linus Torvalds 已提交
876 877 878 879 880 881
		atomic_set(&newsighand->count, 1);
		memcpy(newsighand->action, oldsighand->action,
		       sizeof(newsighand->action));

		write_lock_irq(&tasklist_lock);
		spin_lock(&oldsighand->siglock);
882
		rcu_assign_pointer(tsk->sighand, newsighand);
L
Linus Torvalds 已提交
883 884 885
		spin_unlock(&oldsighand->siglock);
		write_unlock_irq(&tasklist_lock);

886
		__cleanup_sighand(oldsighand);
L
Linus Torvalds 已提交
887 888
	}

889
	BUG_ON(!thread_group_leader(tsk));
L
Linus Torvalds 已提交
890 891
	return 0;
}
O
Oleg Nesterov 已提交
892

L
Linus Torvalds 已提交
893 894 895 896
/*
 * These functions flushes out all traces of the currently running executable
 * so that a new one can be started
 */
897
static void flush_old_files(struct files_struct * files)
L
Linus Torvalds 已提交
898 899
{
	long j = -1;
900
	struct fdtable *fdt;
L
Linus Torvalds 已提交
901 902 903 904 905 906 907

	spin_lock(&files->file_lock);
	for (;;) {
		unsigned long set, i;

		j++;
		i = j * __NFDBITS;
908
		fdt = files_fdtable(files);
909
		if (i >= fdt->max_fds)
L
Linus Torvalds 已提交
910
			break;
911
		set = fdt->close_on_exec->fds_bits[j];
L
Linus Torvalds 已提交
912 913
		if (!set)
			continue;
914
		fdt->close_on_exec->fds_bits[j] = 0;
L
Linus Torvalds 已提交
915 916 917 918 919 920 921 922 923 924 925 926
		spin_unlock(&files->file_lock);
		for ( ; set ; i++,set >>= 1) {
			if (set & 1) {
				sys_close(i);
			}
		}
		spin_lock(&files->file_lock);

	}
	spin_unlock(&files->file_lock);
}

927
char *get_task_comm(char *buf, struct task_struct *tsk)
L
Linus Torvalds 已提交
928 929 930 931 932
{
	/* buf must be at least sizeof(tsk->comm) in size */
	task_lock(tsk);
	strncpy(buf, tsk->comm, sizeof(tsk->comm));
	task_unlock(tsk);
933
	return buf;
L
Linus Torvalds 已提交
934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956
}

void set_task_comm(struct task_struct *tsk, char *buf)
{
	task_lock(tsk);
	strlcpy(tsk->comm, buf, sizeof(tsk->comm));
	task_unlock(tsk);
}

int flush_old_exec(struct linux_binprm * bprm)
{
	char * name;
	int i, ch, retval;
	char tcomm[sizeof(current->comm)];

	/*
	 * Make sure we have a private signal table and that
	 * we are unassociated from the previous thread group.
	 */
	retval = de_thread(current);
	if (retval)
		goto out;

M
Matt Helsley 已提交
957 958
	set_mm_exe_file(bprm->mm, bprm->file);

L
Linus Torvalds 已提交
959 960 961 962 963
	/*
	 * Release all of the old mmap stuff
	 */
	retval = exec_mmap(bprm->mm);
	if (retval)
964
		goto out;
L
Linus Torvalds 已提交
965 966 967 968 969 970 971

	bprm->mm = NULL;		/* We're using it now */

	/* This is the point of no return */
	current->sas_ss_sp = current->sas_ss_size = 0;

	if (current->euid == current->uid && current->egid == current->gid)
972
		set_dumpable(current->mm, 1);
A
Alan Cox 已提交
973
	else
974
		set_dumpable(current->mm, suid_dumpable);
A
Alan Cox 已提交
975

L
Linus Torvalds 已提交
976
	name = bprm->filename;
977 978

	/* Copies the binary name from after last slash */
L
Linus Torvalds 已提交
979 980
	for (i=0; (ch = *(name++)) != '\0';) {
		if (ch == '/')
981
			i = 0; /* overwrite what we wrote */
L
Linus Torvalds 已提交
982 983 984 985 986 987 988 989 990 991
		else
			if (i < (sizeof(tcomm) - 1))
				tcomm[i++] = ch;
	}
	tcomm[i] = '\0';
	set_task_comm(current, tcomm);

	current->flags &= ~PF_RANDOMIZE;
	flush_thread();

992 993 994 995 996 997
	/* Set the new mm task size. We have to do that late because it may
	 * depend on TIF_32BIT which is only updated in flush_thread() on
	 * some architectures like powerpc
	 */
	current->mm->task_size = TASK_SIZE;

998 999 1000 1001 1002 1003
	if (bprm->e_uid != current->euid || bprm->e_gid != current->egid) {
		suid_keys(current);
		set_dumpable(current->mm, suid_dumpable);
		current->pdeath_signal = 0;
	} else if (file_permission(bprm->file, MAY_READ) ||
			(bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
L
Linus Torvalds 已提交
1004
		suid_keys(current);
1005
		set_dumpable(current->mm, suid_dumpable);
L
Linus Torvalds 已提交
1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030
	}

	/* An exec changes our domain. We are no longer part of the thread
	   group */

	current->self_exec_id++;
			
	flush_signal_handlers(current, 0);
	flush_old_files(current->files);

	return 0;

out:
	return retval;
}

EXPORT_SYMBOL(flush_old_exec);

/* 
 * Fill the binprm structure from the inode. 
 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
 */
int prepare_binprm(struct linux_binprm *bprm)
{
	int mode;
1031
	struct inode * inode = bprm->file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1032 1033 1034 1035 1036 1037 1038 1039 1040
	int retval;

	mode = inode->i_mode;
	if (bprm->file->f_op == NULL)
		return -EACCES;

	bprm->e_uid = current->euid;
	bprm->e_gid = current->egid;

1041
	if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
L
Linus Torvalds 已提交
1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070
		/* Set-uid? */
		if (mode & S_ISUID) {
			current->personality &= ~PER_CLEAR_ON_SETID;
			bprm->e_uid = inode->i_uid;
		}

		/* Set-gid? */
		/*
		 * If setgid is set but no group execute bit then this
		 * is a candidate for mandatory locking, not a setgid
		 * executable.
		 */
		if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
			current->personality &= ~PER_CLEAR_ON_SETID;
			bprm->e_gid = inode->i_gid;
		}
	}

	/* fill in binprm security blob */
	retval = security_bprm_set(bprm);
	if (retval)
		return retval;

	memset(bprm->buf,0,BINPRM_BUF_SIZE);
	return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
}

EXPORT_SYMBOL(prepare_binprm);

1071
static int unsafe_exec(struct task_struct *p)
L
Linus Torvalds 已提交
1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091
{
	int unsafe = 0;
	if (p->ptrace & PT_PTRACED) {
		if (p->ptrace & PT_PTRACE_CAP)
			unsafe |= LSM_UNSAFE_PTRACE_CAP;
		else
			unsafe |= LSM_UNSAFE_PTRACE;
	}
	if (atomic_read(&p->fs->count) > 1 ||
	    atomic_read(&p->files->count) > 1 ||
	    atomic_read(&p->sighand->count) > 1)
		unsafe |= LSM_UNSAFE_SHARE;

	return unsafe;
}

void compute_creds(struct linux_binprm *bprm)
{
	int unsafe;

1092
	if (bprm->e_uid != current->uid) {
L
Linus Torvalds 已提交
1093
		suid_keys(current);
1094 1095
		current->pdeath_signal = 0;
	}
L
Linus Torvalds 已提交
1096 1097 1098 1099 1100 1101 1102 1103 1104 1105
	exec_keys(current);

	task_lock(current);
	unsafe = unsafe_exec(current);
	security_bprm_apply_creds(bprm, unsafe);
	task_unlock(current);
	security_bprm_post_apply_creds(bprm);
}
EXPORT_SYMBOL(compute_creds);

N
Nick Piggin 已提交
1106 1107 1108 1109 1110
/*
 * Arguments are '\0' separated strings found at the location bprm->p
 * points to; chop off the first by relocating brpm->p to right after
 * the first '\0' encountered.
 */
1111
int remove_arg_zero(struct linux_binprm *bprm)
L
Linus Torvalds 已提交
1112
{
1113 1114 1115 1116
	int ret = 0;
	unsigned long offset;
	char *kaddr;
	struct page *page;
N
Nick Piggin 已提交
1117

1118 1119
	if (!bprm->argc)
		return 0;
L
Linus Torvalds 已提交
1120

1121 1122 1123 1124 1125 1126 1127 1128
	do {
		offset = bprm->p & ~PAGE_MASK;
		page = get_arg_page(bprm, bprm->p, 0);
		if (!page) {
			ret = -EFAULT;
			goto out;
		}
		kaddr = kmap_atomic(page, KM_USER0);
N
Nick Piggin 已提交
1129

1130 1131 1132
		for (; offset < PAGE_SIZE && kaddr[offset];
				offset++, bprm->p++)
			;
N
Nick Piggin 已提交
1133

1134 1135
		kunmap_atomic(kaddr, KM_USER0);
		put_arg_page(page);
N
Nick Piggin 已提交
1136

1137 1138 1139
		if (offset == PAGE_SIZE)
			free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
	} while (offset == PAGE_SIZE);
N
Nick Piggin 已提交
1140

1141 1142 1143
	bprm->p++;
	bprm->argc--;
	ret = 0;
N
Nick Piggin 已提交
1144

1145 1146
out:
	return ret;
L
Linus Torvalds 已提交
1147 1148 1149 1150 1151 1152 1153 1154 1155 1156
}
EXPORT_SYMBOL(remove_arg_zero);

/*
 * cycle the list of binary formats handler, until one recognizes the image
 */
int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
{
	int try,retval;
	struct linux_binfmt *fmt;
1157
#if defined(__alpha__) && defined(CONFIG_ARCH_SUPPORTS_AOUT)
L
Linus Torvalds 已提交
1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171
	/* handle /sbin/loader.. */
	{
	    struct exec * eh = (struct exec *) bprm->buf;

	    if (!bprm->loader && eh->fh.f_magic == 0x183 &&
		(eh->fh.f_flags & 0x3000) == 0x3000)
	    {
		struct file * file;
		unsigned long loader;

		allow_write_access(bprm->file);
		fput(bprm->file);
		bprm->file = NULL;

1172
		loader = bprm->vma->vm_end - sizeof(void *);
L
Linus Torvalds 已提交
1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198

		file = open_exec("/sbin/loader");
		retval = PTR_ERR(file);
		if (IS_ERR(file))
			return retval;

		/* Remember if the application is TASO.  */
		bprm->sh_bang = eh->ah.entry < 0x100000000UL;

		bprm->file = file;
		bprm->loader = loader;
		retval = prepare_binprm(bprm);
		if (retval<0)
			return retval;
		/* should call search_binary_handler recursively here,
		   but it does not matter */
	    }
	}
#endif
	retval = security_bprm_check(bprm);
	if (retval)
		return retval;

	/* kernel module loader fixup */
	/* so we don't try to load run modprobe in kernel space. */
	set_fs(USER_DS);
A
Al Viro 已提交
1199 1200 1201 1202 1203

	retval = audit_bprm(bprm);
	if (retval)
		return retval;

L
Linus Torvalds 已提交
1204 1205 1206
	retval = -ENOENT;
	for (try=0; try<2; try++) {
		read_lock(&binfmt_lock);
A
Alexey Dobriyan 已提交
1207
		list_for_each_entry(fmt, &formats, lh) {
L
Linus Torvalds 已提交
1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221
			int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
			if (!fn)
				continue;
			if (!try_module_get(fmt->module))
				continue;
			read_unlock(&binfmt_lock);
			retval = fn(bprm, regs);
			if (retval >= 0) {
				put_binfmt(fmt);
				allow_write_access(bprm->file);
				if (bprm->file)
					fput(bprm->file);
				bprm->file = NULL;
				current->did_exec = 1;
M
Matt Helsley 已提交
1222
				proc_exec_connector(current);
L
Linus Torvalds 已提交
1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263
				return retval;
			}
			read_lock(&binfmt_lock);
			put_binfmt(fmt);
			if (retval != -ENOEXEC || bprm->mm == NULL)
				break;
			if (!bprm->file) {
				read_unlock(&binfmt_lock);
				return retval;
			}
		}
		read_unlock(&binfmt_lock);
		if (retval != -ENOEXEC || bprm->mm == NULL) {
			break;
#ifdef CONFIG_KMOD
		}else{
#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
			if (printable(bprm->buf[0]) &&
			    printable(bprm->buf[1]) &&
			    printable(bprm->buf[2]) &&
			    printable(bprm->buf[3]))
				break; /* -ENOEXEC */
			request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
#endif
		}
	}
	return retval;
}

EXPORT_SYMBOL(search_binary_handler);

/*
 * sys_execve() executes a new program.
 */
int do_execve(char * filename,
	char __user *__user *argv,
	char __user *__user *envp,
	struct pt_regs * regs)
{
	struct linux_binprm *bprm;
	struct file *file;
1264
	struct files_struct *displaced;
L
Linus Torvalds 已提交
1265 1266
	int retval;

1267
	retval = unshare_files(&displaced);
1268 1269 1270
	if (retval)
		goto out_ret;

L
Linus Torvalds 已提交
1271
	retval = -ENOMEM;
1272
	bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
L
Linus Torvalds 已提交
1273
	if (!bprm)
1274
		goto out_files;
L
Linus Torvalds 已提交
1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286

	file = open_exec(filename);
	retval = PTR_ERR(file);
	if (IS_ERR(file))
		goto out_kfree;

	sched_exec();

	bprm->file = file;
	bprm->filename = filename;
	bprm->interp = filename;

1287 1288 1289
	retval = bprm_mm_init(bprm);
	if (retval)
		goto out_file;
L
Linus Torvalds 已提交
1290

1291
	bprm->argc = count(argv, MAX_ARG_STRINGS);
L
Linus Torvalds 已提交
1292 1293 1294
	if ((retval = bprm->argc) < 0)
		goto out_mm;

1295
	bprm->envc = count(envp, MAX_ARG_STRINGS);
L
Linus Torvalds 已提交
1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322
	if ((retval = bprm->envc) < 0)
		goto out_mm;

	retval = security_bprm_alloc(bprm);
	if (retval)
		goto out;

	retval = prepare_binprm(bprm);
	if (retval < 0)
		goto out;

	retval = copy_strings_kernel(1, &bprm->filename, bprm);
	if (retval < 0)
		goto out;

	bprm->exec = bprm->p;
	retval = copy_strings(bprm->envc, envp, bprm);
	if (retval < 0)
		goto out;

	retval = copy_strings(bprm->argc, argv, bprm);
	if (retval < 0)
		goto out;

	retval = search_binary_handler(bprm,regs);
	if (retval >= 0) {
		/* execve success */
1323
		free_arg_pages(bprm);
L
Linus Torvalds 已提交
1324 1325 1326
		security_bprm_free(bprm);
		acct_update_integrals(current);
		kfree(bprm);
1327 1328
		if (displaced)
			put_files_struct(displaced);
L
Linus Torvalds 已提交
1329 1330 1331 1332
		return retval;
	}

out:
1333
	free_arg_pages(bprm);
L
Linus Torvalds 已提交
1334 1335 1336 1337 1338
	if (bprm->security)
		security_bprm_free(bprm);

out_mm:
	if (bprm->mm)
1339
		mmput (bprm->mm);
L
Linus Torvalds 已提交
1340 1341 1342 1343 1344 1345 1346 1347 1348

out_file:
	if (bprm->file) {
		allow_write_access(bprm->file);
		fput(bprm->file);
	}
out_kfree:
	kfree(bprm);

1349
out_files:
1350 1351
	if (displaced)
		reset_files_struct(displaced);
L
Linus Torvalds 已提交
1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375
out_ret:
	return retval;
}

int set_binfmt(struct linux_binfmt *new)
{
	struct linux_binfmt *old = current->binfmt;

	if (new) {
		if (!try_module_get(new->module))
			return -1;
	}
	current->binfmt = new;
	if (old)
		module_put(old->module);
	return 0;
}

EXPORT_SYMBOL(set_binfmt);

/* format_corename will inspect the pattern parameter, and output a
 * name into corename, which must have space for at least
 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
 */
1376
static int format_corename(char *corename, const char *pattern, long signr)
L
Linus Torvalds 已提交
1377 1378 1379 1380 1381 1382
{
	const char *pat_ptr = pattern;
	char *out_ptr = corename;
	char *const out_end = corename + CORENAME_MAX_SIZE;
	int rc;
	int pid_in_pattern = 0;
1383 1384 1385 1386
	int ispipe = 0;

	if (*pattern == '|')
		ispipe = 1;
L
Linus Torvalds 已提交
1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408

	/* Repeat as long as we have more pattern to process and more output
	   space */
	while (*pat_ptr) {
		if (*pat_ptr != '%') {
			if (out_ptr == out_end)
				goto out;
			*out_ptr++ = *pat_ptr++;
		} else {
			switch (*++pat_ptr) {
			case 0:
				goto out;
			/* Double percent, output one percent */
			case '%':
				if (out_ptr == out_end)
					goto out;
				*out_ptr++ = '%';
				break;
			/* pid */
			case 'p':
				pid_in_pattern = 1;
				rc = snprintf(out_ptr, out_end - out_ptr,
1409
					      "%d", task_tgid_vnr(current));
L
Linus Torvalds 已提交
1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
			/* uid */
			case 'u':
				rc = snprintf(out_ptr, out_end - out_ptr,
					      "%d", current->uid);
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
			/* gid */
			case 'g':
				rc = snprintf(out_ptr, out_end - out_ptr,
					      "%d", current->gid);
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
			/* signal that caused the coredump */
			case 's':
				rc = snprintf(out_ptr, out_end - out_ptr,
					      "%ld", signr);
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
			/* UNIX time of coredump */
			case 't': {
				struct timeval tv;
				do_gettimeofday(&tv);
				rc = snprintf(out_ptr, out_end - out_ptr,
					      "%lu", tv.tv_sec);
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
			}
			/* hostname */
			case 'h':
				down_read(&uts_sem);
				rc = snprintf(out_ptr, out_end - out_ptr,
1453
					      "%s", utsname()->nodename);
L
Linus Torvalds 已提交
1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466
				up_read(&uts_sem);
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
			/* executable */
			case 'e':
				rc = snprintf(out_ptr, out_end - out_ptr,
					      "%s", current->comm);
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
1467 1468 1469 1470 1471 1472 1473 1474
			/* core limit size */
			case 'c':
				rc = snprintf(out_ptr, out_end - out_ptr,
					      "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
L
Linus Torvalds 已提交
1475 1476 1477 1478 1479 1480 1481 1482 1483 1484
			default:
				break;
			}
			++pat_ptr;
		}
	}
	/* Backward compatibility with core_uses_pid:
	 *
	 * If core_pattern does not include a %p (as is the default)
	 * and core_uses_pid is set, then .%pid will be appended to
1485 1486
	 * the filename. Do not do this for piped commands. */
	if (!ispipe && !pid_in_pattern
L
Linus Torvalds 已提交
1487 1488
            && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
		rc = snprintf(out_ptr, out_end - out_ptr,
1489
			      ".%d", task_tgid_vnr(current));
L
Linus Torvalds 已提交
1490 1491 1492 1493
		if (rc > out_end - out_ptr)
			goto out;
		out_ptr += rc;
	}
1494
out:
L
Linus Torvalds 已提交
1495
	*out_ptr = 0;
1496
	return ispipe;
L
Linus Torvalds 已提交
1497 1498
}

1499
static void zap_process(struct task_struct *start)
1500 1501
{
	struct task_struct *t;
1502

1503 1504
	start->signal->flags = SIGNAL_GROUP_EXIT;
	start->signal->group_stop_count = 0;
1505 1506 1507 1508 1509

	t = start;
	do {
		if (t != current && t->mm) {
			t->mm->core_waiters++;
1510 1511
			sigaddset(&t->pending.signal, SIGKILL);
			signal_wake_up(t, 1);
1512 1513 1514 1515
		}
	} while ((t = next_thread(t)) != start);
}

1516 1517
static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
				int exit_code)
L
Linus Torvalds 已提交
1518 1519
{
	struct task_struct *g, *p;
1520
	unsigned long flags;
1521 1522 1523
	int err = -EAGAIN;

	spin_lock_irq(&tsk->sighand->siglock);
1524
	if (!signal_group_exit(tsk->signal)) {
1525
		tsk->signal->group_exit_code = exit_code;
1526
		zap_process(tsk);
1527
		err = 0;
L
Linus Torvalds 已提交
1528
	}
1529 1530 1531
	spin_unlock_irq(&tsk->sighand->siglock);
	if (err)
		return err;
L
Linus Torvalds 已提交
1532

1533 1534 1535
	if (atomic_read(&mm->mm_users) == mm->core_waiters + 1)
		goto done;

1536
	rcu_read_lock();
1537
	for_each_process(g) {
1538 1539 1540
		if (g == tsk->group_leader)
			continue;

1541 1542 1543
		p = g;
		do {
			if (p->mm) {
1544 1545 1546 1547 1548 1549
				if (p->mm == mm) {
					/*
					 * p->sighand can't disappear, but
					 * may be changed by de_thread()
					 */
					lock_task_sighand(p, &flags);
1550
					zap_process(p);
1551 1552
					unlock_task_sighand(p, &flags);
				}
1553 1554 1555 1556
				break;
			}
		} while ((p = next_thread(p)) != g);
	}
1557
	rcu_read_unlock();
1558
done:
1559
	return mm->core_waiters;
L
Linus Torvalds 已提交
1560 1561
}

1562
static int coredump_wait(int exit_code)
L
Linus Torvalds 已提交
1563
{
1564 1565 1566 1567
	struct task_struct *tsk = current;
	struct mm_struct *mm = tsk->mm;
	struct completion startup_done;
	struct completion *vfork_done;
O
Oleg Nesterov 已提交
1568
	int core_waiters;
L
Linus Torvalds 已提交
1569

1570 1571
	init_completion(&mm->core_done);
	init_completion(&startup_done);
L
Linus Torvalds 已提交
1572 1573
	mm->core_startup_done = &startup_done;

1574
	core_waiters = zap_threads(tsk, mm, exit_code);
O
Oleg Nesterov 已提交
1575 1576
	up_write(&mm->mmap_sem);

1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589
	if (unlikely(core_waiters < 0))
		goto fail;

	/*
	 * Make sure nobody is waiting for us to release the VM,
	 * otherwise we can deadlock when we wait on each other
	 */
	vfork_done = tsk->vfork_done;
	if (vfork_done) {
		tsk->vfork_done = NULL;
		complete(vfork_done);
	}

O
Oleg Nesterov 已提交
1590
	if (core_waiters)
L
Linus Torvalds 已提交
1591
		wait_for_completion(&startup_done);
1592
fail:
L
Linus Torvalds 已提交
1593
	BUG_ON(mm->core_waiters);
1594
	return core_waiters;
L
Linus Torvalds 已提交
1595 1596
}

1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645
/*
 * set_dumpable converts traditional three-value dumpable to two flags and
 * stores them into mm->flags.  It modifies lower two bits of mm->flags, but
 * these bits are not changed atomically.  So get_dumpable can observe the
 * intermediate state.  To avoid doing unexpected behavior, get get_dumpable
 * return either old dumpable or new one by paying attention to the order of
 * modifying the bits.
 *
 * dumpable |   mm->flags (binary)
 * old  new | initial interim  final
 * ---------+-----------------------
 *  0    1  |   00      01      01
 *  0    2  |   00      10(*)   11
 *  1    0  |   01      00      00
 *  1    2  |   01      11      11
 *  2    0  |   11      10(*)   00
 *  2    1  |   11      11      01
 *
 * (*) get_dumpable regards interim value of 10 as 11.
 */
void set_dumpable(struct mm_struct *mm, int value)
{
	switch (value) {
	case 0:
		clear_bit(MMF_DUMPABLE, &mm->flags);
		smp_wmb();
		clear_bit(MMF_DUMP_SECURELY, &mm->flags);
		break;
	case 1:
		set_bit(MMF_DUMPABLE, &mm->flags);
		smp_wmb();
		clear_bit(MMF_DUMP_SECURELY, &mm->flags);
		break;
	case 2:
		set_bit(MMF_DUMP_SECURELY, &mm->flags);
		smp_wmb();
		set_bit(MMF_DUMPABLE, &mm->flags);
		break;
	}
}

int get_dumpable(struct mm_struct *mm)
{
	int ret;

	ret = mm->flags & 0x3;
	return (ret >= 2) ? 2 : ret;
}

L
Linus Torvalds 已提交
1646 1647 1648 1649 1650 1651 1652 1653
int do_coredump(long signr, int exit_code, struct pt_regs * regs)
{
	char corename[CORENAME_MAX_SIZE + 1];
	struct mm_struct *mm = current->mm;
	struct linux_binfmt * binfmt;
	struct inode * inode;
	struct file * file;
	int retval = 0;
A
Alan Cox 已提交
1654 1655
	int fsuid = current->fsuid;
	int flag = 0;
1656
	int ispipe = 0;
1657
	unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
1658 1659 1660
	char **helper_argv = NULL;
	int helper_argc = 0;
	char *delimit;
L
Linus Torvalds 已提交
1661

S
Steve Grubb 已提交
1662 1663
	audit_core_dumps(signr);

L
Linus Torvalds 已提交
1664 1665 1666 1667
	binfmt = current->binfmt;
	if (!binfmt || !binfmt->core_dump)
		goto fail;
	down_write(&mm->mmap_sem);
R
Roland McGrath 已提交
1668 1669 1670 1671
	/*
	 * If another thread got here first, or we are not dumpable, bail out.
	 */
	if (mm->core_waiters || !get_dumpable(mm)) {
L
Linus Torvalds 已提交
1672 1673 1674
		up_write(&mm->mmap_sem);
		goto fail;
	}
A
Alan Cox 已提交
1675 1676 1677 1678 1679 1680

	/*
	 *	We cannot trust fsuid as being the "true" uid of the
	 *	process nor do we know its entire history. We only know it
	 *	was tainted so we dump it as root in mode 2.
	 */
1681
	if (get_dumpable(mm) == 2) {	/* Setuid core dump mode */
A
Alan Cox 已提交
1682 1683 1684
		flag = O_EXCL;		/* Stop rewrite attacks */
		current->fsuid = 0;	/* Dump root private */
	}
1685

1686 1687
	retval = coredump_wait(exit_code);
	if (retval < 0)
1688
		goto fail;
L
Linus Torvalds 已提交
1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700

	/*
	 * Clear any false indication of pending signals that might
	 * be seen by the filesystem code called to write the core file.
	 */
	clear_thread_flag(TIF_SIGPENDING);

	/*
	 * lock_kernel() because format_corename() is controlled by sysctl, which
	 * uses lock_kernel()
	 */
 	lock_kernel();
1701
	ispipe = format_corename(corename, core_pattern, signr);
L
Linus Torvalds 已提交
1702
	unlock_kernel();
1703 1704 1705 1706 1707 1708 1709 1710
	/*
	 * Don't bother to check the RLIMIT_CORE value if core_pattern points
	 * to a pipe.  Since we're not writing directly to the filesystem
	 * RLIMIT_CORE doesn't really apply, as no actual core file will be
	 * created unless the pipe reader choses to write out the core file
	 * at which point file size limits and permissions will be imposed
	 * as it does with any other process
	 */
1711
	if ((!ispipe) && (core_limit < binfmt->min_coredump))
1712 1713
		goto fail_unlock;

1714
 	if (ispipe) {
1715 1716 1717 1718 1719
		helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
		/* Terminate the string before the first option */
		delimit = strchr(corename, ' ');
		if (delimit)
			*delimit = '\0';
1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732
		delimit = strrchr(helper_argv[0], '/');
		if (delimit)
			delimit++;
		else
			delimit = helper_argv[0];
		if (!strcmp(delimit, current->comm)) {
			printk(KERN_NOTICE "Recursive core dump detected, "
					"aborting\n");
			goto fail_unlock;
		}

		core_limit = RLIM_INFINITY;

1733
		/* SIGPIPE can happen, but it's just never processed */
1734 1735
 		if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
				&file)) {
1736 1737 1738 1739 1740 1741
 			printk(KERN_INFO "Core dump to %s pipe failed\n",
			       corename);
 			goto fail_unlock;
 		}
 	} else
 		file = filp_open(corename,
1742 1743
				 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
				 0600);
L
Linus Torvalds 已提交
1744 1745
	if (IS_ERR(file))
		goto fail_unlock;
1746
	inode = file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1747 1748
	if (inode->i_nlink > 1)
		goto close_fail;	/* multiple links - don't dump */
1749
	if (!ispipe && d_unhashed(file->f_path.dentry))
L
Linus Torvalds 已提交
1750 1751
		goto close_fail;

1752 1753 1754
	/* AK: actually i see no reason to not allow this for named pipes etc.,
	   but keep the previous behaviour for now. */
	if (!ispipe && !S_ISREG(inode->i_mode))
L
Linus Torvalds 已提交
1755
		goto close_fail;
I
Ingo Molnar 已提交
1756 1757 1758 1759 1760 1761
	/*
	 * Dont allow local users get cute and trick others to coredump
	 * into their pre-created files:
	 */
	if (inode->i_uid != current->fsuid)
		goto close_fail;
L
Linus Torvalds 已提交
1762 1763 1764 1765
	if (!file->f_op)
		goto close_fail;
	if (!file->f_op->write)
		goto close_fail;
1766
	if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
L
Linus Torvalds 已提交
1767 1768
		goto close_fail;

1769
	retval = binfmt->core_dump(signr, regs, file, core_limit);
L
Linus Torvalds 已提交
1770 1771 1772 1773 1774 1775

	if (retval)
		current->signal->group_exit_code |= 0x80;
close_fail:
	filp_close(file, NULL);
fail_unlock:
1776 1777 1778
	if (helper_argv)
		argv_free(helper_argv);

A
Alan Cox 已提交
1779
	current->fsuid = fsuid;
L
Linus Torvalds 已提交
1780 1781 1782 1783
	complete_all(&mm->core_done);
fail:
	return retval;
}