1/*
   2 *  linux/fs/exec.c
   3 *
   4 *  Copyright (C) 1991, 1992  Linus Torvalds
   5 */
   6
   7/*
   8 * #!-checking implemented by tytso.
   9 */
  10/*
  11 * Demand-loading implemented 01.12.91 - no need to read anything but
  12 * the header into memory. The inode of the executable is put into
  13 * "current->executable", and page faults do the actual loading. Clean.
  14 *
  15 * Once more I can proudly say that linux stood up to being changed: it
  16 * was less than 2 hours work to get demand-loading completely implemented.
  17 *
  18 * Demand loading changed July 1993 by Eric Youngdale.   Use mmap instead,
  19 * current->executable is only used by the procfs.  This allows a dispatch
  20 * table to check for several different types  of binary formats.  We keep
  21 * trying until we recognize the file or we run out of supported binary
  22 * formats. 
  23 */
  24
 
  25#include <linux/slab.h>
  26#include <linux/file.h>
  27#include <linux/fdtable.h>
  28#include <linux/mm.h>
  29#include <linux/stat.h>
  30#include <linux/fcntl.h>
  31#include <linux/swap.h>
  32#include <linux/string.h>
  33#include <linux/init.h>
 
 
 
 
 
  34#include <linux/pagemap.h>
  35#include <linux/perf_event.h>
  36#include <linux/highmem.h>
  37#include <linux/spinlock.h>
  38#include <linux/key.h>
  39#include <linux/personality.h>
  40#include <linux/binfmts.h>
  41#include <linux/utsname.h>
  42#include <linux/pid_namespace.h>
  43#include <linux/module.h>
  44#include <linux/namei.h>
  45#include <linux/mount.h>
  46#include <linux/security.h>
  47#include <linux/syscalls.h>
  48#include <linux/tsacct_kern.h>
  49#include <linux/cn_proc.h>
  50#include <linux/audit.h>
  51#include <linux/tracehook.h>
  52#include <linux/kmod.h>
  53#include <linux/fsnotify.h>
  54#include <linux/fs_struct.h>
  55#include <linux/pipe_fs_i.h>
  56#include <linux/oom.h>
  57#include <linux/compat.h>
 
 
 
 
 
 
 
 
  58
  59#include <asm/uaccess.h>
  60#include <asm/mmu_context.h>
  61#include <asm/tlb.h>
 
 
  62#include "internal.h"
  63
  64int core_uses_pid;
  65char core_pattern[CORENAME_MAX_SIZE] = "core";
  66unsigned int core_pipe_limit;
  67int suid_dumpable = 0;
  68
  69struct core_name {
  70	char *corename;
  71	int used, size;
  72};
  73static atomic_t call_count = ATOMIC_INIT(1);
  74
  75/* The maximal length of core_pattern is also specified in sysctl.c */
  76
  77static LIST_HEAD(formats);
  78static DEFINE_RWLOCK(binfmt_lock);
  79
  80int __register_binfmt(struct linux_binfmt * fmt, int insert)
  81{
  82	if (!fmt)
  83		return -EINVAL;
  84	write_lock(&binfmt_lock);
  85	insert ? list_add(&fmt->lh, &formats) :
  86		 list_add_tail(&fmt->lh, &formats);
  87	write_unlock(&binfmt_lock);
  88	return 0;	
  89}
  90
  91EXPORT_SYMBOL(__register_binfmt);
  92
  93void unregister_binfmt(struct linux_binfmt * fmt)
  94{
  95	write_lock(&binfmt_lock);
  96	list_del(&fmt->lh);
  97	write_unlock(&binfmt_lock);
  98}
  99
 100EXPORT_SYMBOL(unregister_binfmt);
 101
 102static inline void put_binfmt(struct linux_binfmt * fmt)
 103{
 104	module_put(fmt->module);
 105}
 106
 
 
 
 
 
 
 
 107/*
 108 * Note that a shared library must be both readable and executable due to
 109 * security reasons.
 110 *
 111 * Also note that we take the address to load from from the file itself.
 112 */
 113SYSCALL_DEFINE1(uselib, const char __user *, library)
 114{
 
 115	struct file *file;
 116	char *tmp = getname(library);
 117	int error = PTR_ERR(tmp);
 118	static const struct open_flags uselib_flags = {
 119		.open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
 120		.acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN,
 121		.intent = LOOKUP_OPEN
 
 122	};
 123
 124	if (IS_ERR(tmp))
 125		goto out;
 126
 127	file = do_filp_open(AT_FDCWD, tmp, &uselib_flags, LOOKUP_FOLLOW);
 128	putname(tmp);
 129	error = PTR_ERR(file);
 130	if (IS_ERR(file))
 131		goto out;
 132
 133	error = -EINVAL;
 134	if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
 135		goto exit;
 136
 
 137	error = -EACCES;
 138	if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
 
 139		goto exit;
 140
 141	fsnotify_open(file);
 142
 143	error = -ENOEXEC;
 144	if(file->f_op) {
 145		struct linux_binfmt * fmt;
 146
 147		read_lock(&binfmt_lock);
 148		list_for_each_entry(fmt, &formats, lh) {
 149			if (!fmt->load_shlib)
 150				continue;
 151			if (!try_module_get(fmt->module))
 152				continue;
 153			read_unlock(&binfmt_lock);
 154			error = fmt->load_shlib(file);
 155			read_lock(&binfmt_lock);
 156			put_binfmt(fmt);
 157			if (error != -ENOEXEC)
 158				break;
 159		}
 160		read_unlock(&binfmt_lock);
 
 
 
 
 
 161	}
 
 162exit:
 163	fput(file);
 164out:
 165  	return error;
 166}
 
 167
 168#ifdef CONFIG_MMU
 169/*
 170 * The nascent bprm->mm is not visible until exec_mmap() but it can
 171 * use a lot of memory, account these pages in current->mm temporary
 172 * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
 173 * change the counter back via acct_arg_size(0).
 174 */
 175static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 176{
 177	struct mm_struct *mm = current->mm;
 178	long diff = (long)(pages - bprm->vma_pages);
 179
 180	if (!mm || !diff)
 181		return;
 182
 183	bprm->vma_pages = pages;
 184	add_mm_counter(mm, MM_ANONPAGES, diff);
 185}
 186
 187static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 188		int write)
 189{
 190	struct page *page;
 
 
 191	int ret;
 192
 193#ifdef CONFIG_STACK_GROWSUP
 194	if (write) {
 195		ret = expand_downwards(bprm->vma, pos);
 196		if (ret < 0)
 
 
 
 
 
 
 197			return NULL;
 198	}
 199#endif
 200	ret = get_user_pages(current, bprm->mm, pos,
 201			1, write, 1, &page, NULL);
 
 
 
 
 
 
 
 
 
 202	if (ret <= 0)
 203		return NULL;
 204
 205	if (write) {
 206		unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
 207		struct rlimit *rlim;
 208
 209		acct_arg_size(bprm, size / PAGE_SIZE);
 210
 211		/*
 212		 * We've historically supported up to 32 pages (ARG_MAX)
 213		 * of argument strings even with small stacks
 214		 */
 215		if (size <= ARG_MAX)
 216			return page;
 217
 218		/*
 219		 * Limit to 1/4-th the stack size for the argv+env strings.
 220		 * This ensures that:
 221		 *  - the remaining binfmt code will not run out of stack space,
 222		 *  - the program will have a reasonable amount of stack left
 223		 *    to work from.
 224		 */
 225		rlim = current->signal->rlim;
 226		if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
 227			put_page(page);
 228			return NULL;
 229		}
 230	}
 231
 232	return page;
 233}
 234
 235static void put_arg_page(struct page *page)
 236{
 237	put_page(page);
 238}
 239
 240static void free_arg_page(struct linux_binprm *bprm, int i)
 241{
 242}
 243
 244static void free_arg_pages(struct linux_binprm *bprm)
 245{
 246}
 247
 248static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 249		struct page *page)
 250{
 251	flush_cache_page(bprm->vma, pos, page_to_pfn(page));
 252}
 253
 254static int __bprm_mm_init(struct linux_binprm *bprm)
 255{
 256	int err;
 257	struct vm_area_struct *vma = NULL;
 258	struct mm_struct *mm = bprm->mm;
 259
 260	bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
 261	if (!vma)
 262		return -ENOMEM;
 
 263
 264	down_write(&mm->mmap_sem);
 265	vma->vm_mm = mm;
 
 
 
 
 
 
 
 
 
 
 266
 267	/*
 268	 * Place the stack at the largest stack address the architecture
 269	 * supports. Later, we'll move this to an appropriate place. We don't
 270	 * use STACK_TOP because that can depend on attributes which aren't
 271	 * configured yet.
 272	 */
 273	BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
 274	vma->vm_end = STACK_TOP_MAX;
 275	vma->vm_start = vma->vm_end - PAGE_SIZE;
 276	vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
 277	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 278	INIT_LIST_HEAD(&vma->anon_vma_chain);
 279
 280	err = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1);
 281	if (err)
 282		goto err;
 283
 284	err = insert_vm_struct(mm, vma);
 285	if (err)
 286		goto err;
 287
 288	mm->stack_vm = mm->total_vm = 1;
 289	up_write(&mm->mmap_sem);
 290	bprm->p = vma->vm_end - sizeof(void *);
 291	return 0;
 292err:
 293	up_write(&mm->mmap_sem);
 
 
 
 294	bprm->vma = NULL;
 295	kmem_cache_free(vm_area_cachep, vma);
 296	return err;
 297}
 298
 299static bool valid_arg_len(struct linux_binprm *bprm, long len)
 300{
 301	return len <= MAX_ARG_STRLEN;
 302}
 303
 304#else
 305
 306static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 307{
 308}
 309
 310static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 311		int write)
 312{
 313	struct page *page;
 314
 315	page = bprm->page[pos / PAGE_SIZE];
 316	if (!page && write) {
 317		page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
 318		if (!page)
 319			return NULL;
 320		bprm->page[pos / PAGE_SIZE] = page;
 321	}
 322
 323	return page;
 324}
 325
 326static void put_arg_page(struct page *page)
 327{
 328}
 329
 330static void free_arg_page(struct linux_binprm *bprm, int i)
 331{
 332	if (bprm->page[i]) {
 333		__free_page(bprm->page[i]);
 334		bprm->page[i] = NULL;
 335	}
 336}
 337
 338static void free_arg_pages(struct linux_binprm *bprm)
 339{
 340	int i;
 341
 342	for (i = 0; i < MAX_ARG_PAGES; i++)
 343		free_arg_page(bprm, i);
 344}
 345
 346static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 347		struct page *page)
 348{
 349}
 350
 351static int __bprm_mm_init(struct linux_binprm *bprm)
 352{
 353	bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
 354	return 0;
 355}
 356
 357static bool valid_arg_len(struct linux_binprm *bprm, long len)
 358{
 359	return len <= bprm->p;
 360}
 361
 362#endif /* CONFIG_MMU */
 363
 364/*
 365 * Create a new mm_struct and populate it with a temporary stack
 366 * vm_area_struct.  We don't have enough context at this point to set the stack
 367 * flags, permissions, and offset, so we use temporary values.  We'll update
 368 * them later in setup_arg_pages().
 369 */
 370int bprm_mm_init(struct linux_binprm *bprm)
 371{
 372	int err;
 373	struct mm_struct *mm = NULL;
 374
 375	bprm->mm = mm = mm_alloc();
 376	err = -ENOMEM;
 377	if (!mm)
 378		goto err;
 379
 380	err = init_new_context(current, mm);
 381	if (err)
 382		goto err;
 
 383
 384	err = __bprm_mm_init(bprm);
 385	if (err)
 386		goto err;
 387
 388	return 0;
 389
 390err:
 391	if (mm) {
 392		bprm->mm = NULL;
 393		mmdrop(mm);
 394	}
 395
 396	return err;
 397}
 398
 399struct user_arg_ptr {
 400#ifdef CONFIG_COMPAT
 401	bool is_compat;
 402#endif
 403	union {
 404		const char __user *const __user *native;
 405#ifdef CONFIG_COMPAT
 406		compat_uptr_t __user *compat;
 407#endif
 408	} ptr;
 409};
 410
 411static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
 412{
 413	const char __user *native;
 414
 415#ifdef CONFIG_COMPAT
 416	if (unlikely(argv.is_compat)) {
 417		compat_uptr_t compat;
 418
 419		if (get_user(compat, argv.ptr.compat + nr))
 420			return ERR_PTR(-EFAULT);
 421
 422		return compat_ptr(compat);
 423	}
 424#endif
 425
 426	if (get_user(native, argv.ptr.native + nr))
 427		return ERR_PTR(-EFAULT);
 428
 429	return native;
 430}
 431
 432/*
 433 * count() counts the number of strings in array ARGV.
 434 */
 435static int count(struct user_arg_ptr argv, int max)
 436{
 437	int i = 0;
 438
 439	if (argv.ptr.native != NULL) {
 440		for (;;) {
 441			const char __user *p = get_user_arg_ptr(argv, i);
 442
 443			if (!p)
 444				break;
 445
 446			if (IS_ERR(p))
 447				return -EFAULT;
 448
 449			if (i++ >= max)
 450				return -E2BIG;
 
 451
 452			if (fatal_signal_pending(current))
 453				return -ERESTARTNOHAND;
 454			cond_resched();
 455		}
 456	}
 457	return i;
 458}
 459
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 460/*
 461 * 'copy_strings()' copies argument/environment strings from the old
 462 * processes's memory to the new process's stack.  The call to get_user_pages()
 463 * ensures the destination page is created and not swapped out.
 464 */
 465static int copy_strings(int argc, struct user_arg_ptr argv,
 466			struct linux_binprm *bprm)
 467{
 468	struct page *kmapped_page = NULL;
 469	char *kaddr = NULL;
 470	unsigned long kpos = 0;
 471	int ret;
 472
 473	while (argc-- > 0) {
 474		const char __user *str;
 475		int len;
 476		unsigned long pos;
 477
 478		ret = -EFAULT;
 479		str = get_user_arg_ptr(argv, argc);
 480		if (IS_ERR(str))
 481			goto out;
 482
 483		len = strnlen_user(str, MAX_ARG_STRLEN);
 484		if (!len)
 485			goto out;
 486
 487		ret = -E2BIG;
 488		if (!valid_arg_len(bprm, len))
 489			goto out;
 490
 491		/* We're going to work our way backwords. */
 492		pos = bprm->p;
 493		str += len;
 494		bprm->p -= len;
 
 
 
 
 495
 496		while (len > 0) {
 497			int offset, bytes_to_copy;
 498
 499			if (fatal_signal_pending(current)) {
 500				ret = -ERESTARTNOHAND;
 501				goto out;
 502			}
 503			cond_resched();
 504
 505			offset = pos % PAGE_SIZE;
 506			if (offset == 0)
 507				offset = PAGE_SIZE;
 508
 509			bytes_to_copy = offset;
 510			if (bytes_to_copy > len)
 511				bytes_to_copy = len;
 512
 513			offset -= bytes_to_copy;
 514			pos -= bytes_to_copy;
 515			str -= bytes_to_copy;
 516			len -= bytes_to_copy;
 517
 518			if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
 519				struct page *page;
 520
 521				page = get_arg_page(bprm, pos, 1);
 522				if (!page) {
 523					ret = -E2BIG;
 524					goto out;
 525				}
 526
 527				if (kmapped_page) {
 528					flush_kernel_dcache_page(kmapped_page);
 529					kunmap(kmapped_page);
 530					put_arg_page(kmapped_page);
 531				}
 532				kmapped_page = page;
 533				kaddr = kmap(kmapped_page);
 534				kpos = pos & PAGE_MASK;
 535				flush_arg_page(bprm, kpos, kmapped_page);
 536			}
 537			if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
 538				ret = -EFAULT;
 539				goto out;
 540			}
 541		}
 542	}
 543	ret = 0;
 544out:
 545	if (kmapped_page) {
 546		flush_kernel_dcache_page(kmapped_page);
 547		kunmap(kmapped_page);
 548		put_arg_page(kmapped_page);
 549	}
 550	return ret;
 551}
 552
 553/*
 554 * Like copy_strings, but get argv and its values from kernel memory.
 555 */
 556int copy_strings_kernel(int argc, const char *const *__argv,
 557			struct linux_binprm *bprm)
 558{
 559	int r;
 560	mm_segment_t oldfs = get_fs();
 561	struct user_arg_ptr argv = {
 562		.ptr.native = (const char __user *const  __user *)__argv,
 563	};
 564
 565	set_fs(KERNEL_DS);
 566	r = copy_strings(argc, argv, bprm);
 567	set_fs(oldfs);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 568
 569	return r;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 570}
 571EXPORT_SYMBOL(copy_strings_kernel);
 572
 573#ifdef CONFIG_MMU
 574
 575/*
 576 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 577 * the binfmt code determines where the new stack should reside, we shift it to
 578 * its final location.  The process proceeds as follows:
 579 *
 580 * 1) Use shift to calculate the new vma endpoints.
 581 * 2) Extend vma to cover both the old and new ranges.  This ensures the
 582 *    arguments passed to subsequent functions are consistent.
 583 * 3) Move vma's page tables to the new range.
 584 * 4) Free up any cleared pgd range.
 585 * 5) Shrink the vma to cover only the new range.
 586 */
 587static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 588{
 589	struct mm_struct *mm = vma->vm_mm;
 590	unsigned long old_start = vma->vm_start;
 591	unsigned long old_end = vma->vm_end;
 592	unsigned long length = old_end - old_start;
 593	unsigned long new_start = old_start - shift;
 594	unsigned long new_end = old_end - shift;
 
 
 595	struct mmu_gather tlb;
 596
 597	BUG_ON(new_start > new_end);
 598
 599	/*
 600	 * ensure there are no vmas between where we want to go
 601	 * and where we are
 602	 */
 603	if (vma != find_vma(mm, new_start))
 604		return -EFAULT;
 605
 
 606	/*
 607	 * cover the whole range: [new_start, old_end)
 608	 */
 609	if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
 610		return -ENOMEM;
 611
 612	/*
 613	 * move the page tables downwards, on failure we rely on
 614	 * process cleanup to remove whatever mess we made.
 615	 */
 616	if (length != move_page_tables(vma, old_start,
 617				       vma, new_start, length))
 618		return -ENOMEM;
 619
 620	lru_add_drain();
 621	tlb_gather_mmu(&tlb, mm, 0);
 
 622	if (new_end > old_start) {
 623		/*
 624		 * when the old and new regions overlap clear from new_end.
 625		 */
 626		free_pgd_range(&tlb, new_end, old_end, new_end,
 627			vma->vm_next ? vma->vm_next->vm_start : 0);
 628	} else {
 629		/*
 630		 * otherwise, clean from old_start; this is done to not touch
 631		 * the address space in [new_end, old_start) some architectures
 632		 * have constraints on va-space that make this illegal (IA64) -
 633		 * for the others its just a little faster.
 634		 */
 635		free_pgd_range(&tlb, old_start, old_end, new_end,
 636			vma->vm_next ? vma->vm_next->vm_start : 0);
 637	}
 638	tlb_finish_mmu(&tlb, new_end, old_end);
 639
 640	/*
 641	 * Shrink the vma to just the new range.  Always succeeds.
 642	 */
 643	vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
 644
 645	return 0;
 646}
 647
 648/*
 649 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 650 * the stack is optionally relocated, and some extra space is added.
 651 */
 652int setup_arg_pages(struct linux_binprm *bprm,
 653		    unsigned long stack_top,
 654		    int executable_stack)
 655{
 656	unsigned long ret;
 657	unsigned long stack_shift;
 658	struct mm_struct *mm = current->mm;
 659	struct vm_area_struct *vma = bprm->vma;
 660	struct vm_area_struct *prev = NULL;
 661	unsigned long vm_flags;
 662	unsigned long stack_base;
 663	unsigned long stack_size;
 664	unsigned long stack_expand;
 665	unsigned long rlim_stack;
 
 
 666
 667#ifdef CONFIG_STACK_GROWSUP
 668	/* Limit stack size to 1GB */
 669	stack_base = rlimit_max(RLIMIT_STACK);
 670	if (stack_base > (1 << 30))
 671		stack_base = 1 << 30;
 
 
 
 672
 673	/* Make sure we didn't let the argument array grow too large. */
 674	if (vma->vm_end - vma->vm_start > stack_base)
 675		return -ENOMEM;
 676
 677	stack_base = PAGE_ALIGN(stack_top - stack_base);
 678
 679	stack_shift = vma->vm_start - stack_base;
 680	mm->arg_start = bprm->p - stack_shift;
 681	bprm->p = vma->vm_end - stack_shift;
 682#else
 683	stack_top = arch_align_stack(stack_top);
 684	stack_top = PAGE_ALIGN(stack_top);
 685
 686	if (unlikely(stack_top < mmap_min_addr) ||
 687	    unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
 688		return -ENOMEM;
 689
 690	stack_shift = vma->vm_end - stack_top;
 691
 692	bprm->p -= stack_shift;
 693	mm->arg_start = bprm->p;
 694#endif
 695
 696	if (bprm->loader)
 697		bprm->loader -= stack_shift;
 698	bprm->exec -= stack_shift;
 699
 700	down_write(&mm->mmap_sem);
 
 
 701	vm_flags = VM_STACK_FLAGS;
 702
 703	/*
 704	 * Adjust stack execute permissions; explicitly enable for
 705	 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
 706	 * (arch default) otherwise.
 707	 */
 708	if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 709		vm_flags |= VM_EXEC;
 710	else if (executable_stack == EXSTACK_DISABLE_X)
 711		vm_flags &= ~VM_EXEC;
 712	vm_flags |= mm->def_flags;
 713	vm_flags |= VM_STACK_INCOMPLETE_SETUP;
 714
 715	ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
 
 
 
 716			vm_flags);
 
 
 717	if (ret)
 718		goto out_unlock;
 719	BUG_ON(prev != vma);
 720
 
 
 
 
 
 721	/* Move stack pages down in memory. */
 722	if (stack_shift) {
 723		ret = shift_arg_pages(vma, stack_shift);
 724		if (ret)
 725			goto out_unlock;
 726	}
 727
 728	/* mprotect_fixup is overkill to remove the temporary stack flags */
 729	vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
 730
 731	stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
 732	stack_size = vma->vm_end - vma->vm_start;
 733	/*
 734	 * Align this down to a page boundary as expand_stack
 735	 * will align it up.
 736	 */
 737	rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK;
 
 
 
 738#ifdef CONFIG_STACK_GROWSUP
 739	if (stack_size + stack_expand > rlim_stack)
 740		stack_base = vma->vm_start + rlim_stack;
 741	else
 742		stack_base = vma->vm_end + stack_expand;
 743#else
 744	if (stack_size + stack_expand > rlim_stack)
 745		stack_base = vma->vm_end - rlim_stack;
 746	else
 747		stack_base = vma->vm_start - stack_expand;
 748#endif
 749	current->mm->start_stack = bprm->p;
 750	ret = expand_stack(vma, stack_base);
 751	if (ret)
 752		ret = -EFAULT;
 753
 754out_unlock:
 755	up_write(&mm->mmap_sem);
 756	return ret;
 757}
 758EXPORT_SYMBOL(setup_arg_pages);
 759
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 760#endif /* CONFIG_MMU */
 761
 762struct file *open_exec(const char *name)
 
 
 
 
 763{
 764	struct file *file;
 765	int err;
 766	static const struct open_flags open_exec_flags = {
 767		.open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
 768		.acc_mode = MAY_EXEC | MAY_OPEN,
 769		.intent = LOOKUP_OPEN
 
 770	};
 771
 772	file = do_filp_open(AT_FDCWD, name, &open_exec_flags, LOOKUP_FOLLOW);
 
 
 
 
 
 
 
 773	if (IS_ERR(file))
 774		goto out;
 775
 
 
 
 
 
 776	err = -EACCES;
 777	if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
 778		goto exit;
 779
 780	if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
 781		goto exit;
 782
 783	fsnotify_open(file);
 784
 785	err = deny_write_access(file);
 786	if (err)
 787		goto exit;
 788
 789out:
 790	return file;
 791
 792exit:
 793	fput(file);
 794	return ERR_PTR(err);
 795}
 796EXPORT_SYMBOL(open_exec);
 797
 798int kernel_read(struct file *file, loff_t offset,
 799		char *addr, unsigned long count)
 
 
 
 
 
 
 
 
 
 
 800{
 801	mm_segment_t old_fs;
 802	loff_t pos = offset;
 803	int result;
 804
 805	old_fs = get_fs();
 806	set_fs(get_ds());
 807	/* The cast to a user pointer is valid due to the set_fs() */
 808	result = vfs_read(file, (void __user *)addr, count, &pos);
 809	set_fs(old_fs);
 810	return result;
 811}
 
 812
 813EXPORT_SYMBOL(kernel_read);
 
 
 
 
 
 
 
 
 
 814
 
 
 
 
 
 815static int exec_mmap(struct mm_struct *mm)
 816{
 817	struct task_struct *tsk;
 818	struct mm_struct * old_mm, *active_mm;
 
 819
 820	/* Notify parent that we're no longer interested in the old VM */
 821	tsk = current;
 822	old_mm = current->mm;
 823	sync_mm_rss(tsk, old_mm);
 824	mm_release(tsk, old_mm);
 
 
 
 825
 826	if (old_mm) {
 827		/*
 828		 * Make sure that if there is a core dump in progress
 829		 * for the old mm, we get out and die instead of going
 830		 * through with the exec.  We must hold mmap_sem around
 831		 * checking core_state and changing tsk->mm.
 832		 */
 833		down_read(&old_mm->mmap_sem);
 834		if (unlikely(old_mm->core_state)) {
 835			up_read(&old_mm->mmap_sem);
 836			return -EINTR;
 837		}
 838	}
 
 839	task_lock(tsk);
 
 
 
 840	active_mm = tsk->active_mm;
 841	tsk->mm = mm;
 842	tsk->active_mm = mm;
 
 
 
 
 
 
 
 
 
 
 
 843	activate_mm(active_mm, mm);
 844	if (old_mm && tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) {
 845		atomic_dec(&old_mm->oom_disable_count);
 846		atomic_inc(&tsk->mm->oom_disable_count);
 847	}
 848	task_unlock(tsk);
 849	arch_pick_mmap_layout(mm);
 850	if (old_mm) {
 851		up_read(&old_mm->mmap_sem);
 852		BUG_ON(active_mm != old_mm);
 
 853		mm_update_next_owner(old_mm);
 854		mmput(old_mm);
 855		return 0;
 856	}
 857	mmdrop(active_mm);
 858	return 0;
 859}
 860
 861/*
 862 * This function makes sure the current process has its own signal table,
 863 * so that flush_signal_handlers can later reset the handlers without
 864 * disturbing other processes.  (Other processes might share the signal
 865 * table via the CLONE_SIGHAND option to clone().)
 866 */
 867static int de_thread(struct task_struct *tsk)
 868{
 869	struct signal_struct *sig = tsk->signal;
 870	struct sighand_struct *oldsighand = tsk->sighand;
 871	spinlock_t *lock = &oldsighand->siglock;
 872
 873	if (thread_group_empty(tsk))
 874		goto no_thread_group;
 875
 876	/*
 877	 * Kill all other threads in the thread group.
 878	 */
 879	spin_lock_irq(lock);
 880	if (signal_group_exit(sig)) {
 881		/*
 882		 * Another group action in progress, just
 883		 * return so that the signal is processed.
 884		 */
 885		spin_unlock_irq(lock);
 886		return -EAGAIN;
 887	}
 888
 889	sig->group_exit_task = tsk;
 890	sig->notify_count = zap_other_threads(tsk);
 891	if (!thread_group_leader(tsk))
 892		sig->notify_count--;
 893
 894	while (sig->notify_count) {
 895		__set_current_state(TASK_UNINTERRUPTIBLE);
 896		spin_unlock_irq(lock);
 897		schedule();
 
 
 898		spin_lock_irq(lock);
 899	}
 900	spin_unlock_irq(lock);
 901
 902	/*
 903	 * At this point all other threads have exited, all we have to
 904	 * do is to wait for the thread group leader to become inactive,
 905	 * and to assume its PID:
 906	 */
 907	if (!thread_group_leader(tsk)) {
 908		struct task_struct *leader = tsk->group_leader;
 909
 910		sig->notify_count = -1;	/* for exit_notify() */
 911		for (;;) {
 
 912			write_lock_irq(&tasklist_lock);
 
 
 
 
 
 913			if (likely(leader->exit_state))
 914				break;
 915			__set_current_state(TASK_UNINTERRUPTIBLE);
 916			write_unlock_irq(&tasklist_lock);
 
 917			schedule();
 
 
 918		}
 919
 920		/*
 921		 * The only record we have of the real-time age of a
 922		 * process, regardless of execs it's done, is start_time.
 923		 * All the past CPU time is accumulated in signal_struct
 924		 * from sister threads now dead.  But in this non-leader
 925		 * exec, nothing survives from the original leader thread,
 926		 * whose birth marks the true age of this process now.
 927		 * When we take on its identity by switching to its PID, we
 928		 * also take its birthdate (always earlier than our own).
 929		 */
 930		tsk->start_time = leader->start_time;
 
 931
 932		BUG_ON(!same_thread_group(leader, tsk));
 933		BUG_ON(has_group_leader_pid(tsk));
 934		/*
 935		 * An exec() starts a new thread group with the
 936		 * TGID of the previous thread group. Rehash the
 937		 * two threads with a switched PID, and release
 938		 * the former thread group leader:
 939		 */
 940
 941		/* Become a process group leader with the old leader's pid.
 942		 * The old leader becomes a thread of the this thread group.
 943		 * Note: The old leader also uses this pid until release_task
 944		 *       is called.  Odd but simple and correct.
 945		 */
 946		detach_pid(tsk, PIDTYPE_PID);
 947		tsk->pid = leader->pid;
 948		attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
 949		transfer_pid(leader, tsk, PIDTYPE_PGID);
 950		transfer_pid(leader, tsk, PIDTYPE_SID);
 951
 952		list_replace_rcu(&leader->tasks, &tsk->tasks);
 953		list_replace_init(&leader->sibling, &tsk->sibling);
 954
 955		tsk->group_leader = tsk;
 956		leader->group_leader = tsk;
 957
 958		tsk->exit_signal = SIGCHLD;
 959		leader->exit_signal = -1;
 960
 961		BUG_ON(leader->exit_state != EXIT_ZOMBIE);
 962		leader->exit_state = EXIT_DEAD;
 963
 964		/*
 965		 * We are going to release_task()->ptrace_unlink() silently,
 966		 * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
 967		 * the tracer wont't block again waiting for this thread.
 968		 */
 969		if (unlikely(leader->ptrace))
 970			__wake_up_parent(leader, leader->parent);
 971		write_unlock_irq(&tasklist_lock);
 
 972
 973		release_task(leader);
 974	}
 975
 976	sig->group_exit_task = NULL;
 977	sig->notify_count = 0;
 978
 979no_thread_group:
 980	if (current->mm)
 981		setmax_mm_hiwater_rss(&sig->maxrss, current->mm);
 
 
 
 
 
 
 
 
 
 
 
 
 982
 983	exit_itimers(sig);
 984	flush_itimer_signals();
 985
 986	if (atomic_read(&oldsighand->count) != 1) {
 
 
 
 
 
 
 
 
 
 
 987		struct sighand_struct *newsighand;
 988		/*
 989		 * This ->sighand is shared with the CLONE_SIGHAND
 990		 * but not CLONE_THREAD task, switch to the new one.
 991		 */
 992		newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
 993		if (!newsighand)
 994			return -ENOMEM;
 995
 996		atomic_set(&newsighand->count, 1);
 997		memcpy(newsighand->action, oldsighand->action,
 998		       sizeof(newsighand->action));
 999
1000		write_lock_irq(&tasklist_lock);
1001		spin_lock(&oldsighand->siglock);
1002		rcu_assign_pointer(tsk->sighand, newsighand);
 
 
1003		spin_unlock(&oldsighand->siglock);
1004		write_unlock_irq(&tasklist_lock);
1005
1006		__cleanup_sighand(oldsighand);
1007	}
1008
1009	BUG_ON(!thread_group_leader(tsk));
1010	return 0;
1011}
1012
 
 
 
 
 
 
 
 
 
 
1013/*
1014 * These functions flushes out all traces of the currently running executable
1015 * so that a new one can be started
1016 */
1017static void flush_old_files(struct files_struct * files)
1018{
1019	long j = -1;
1020	struct fdtable *fdt;
1021
1022	spin_lock(&files->file_lock);
1023	for (;;) {
1024		unsigned long set, i;
1025
1026		j++;
1027		i = j * __NFDBITS;
1028		fdt = files_fdtable(files);
1029		if (i >= fdt->max_fds)
1030			break;
1031		set = fdt->close_on_exec->fds_bits[j];
1032		if (!set)
1033			continue;
1034		fdt->close_on_exec->fds_bits[j] = 0;
1035		spin_unlock(&files->file_lock);
1036		for ( ; set ; i++,set >>= 1) {
1037			if (set & 1) {
1038				sys_close(i);
1039			}
1040		}
1041		spin_lock(&files->file_lock);
1042
1043	}
1044	spin_unlock(&files->file_lock);
1045}
1046
1047char *get_task_comm(char *buf, struct task_struct *tsk)
1048{
1049	/* buf must be at least sizeof(tsk->comm) in size */
1050	task_lock(tsk);
1051	strncpy(buf, tsk->comm, sizeof(tsk->comm));
 
1052	task_unlock(tsk);
1053	return buf;
1054}
1055EXPORT_SYMBOL_GPL(get_task_comm);
1056
1057void set_task_comm(struct task_struct *tsk, char *buf)
 
 
 
 
 
 
1058{
1059	task_lock(tsk);
 
 
 
 
 
 
1060
1061	/*
1062	 * Threads may access current->comm without holding
1063	 * the task lock, so write the string carefully.
1064	 * Readers without a lock may see incomplete new
1065	 * names but are safe from non-terminating string reads.
1066	 */
1067	memset(tsk->comm, 0, TASK_COMM_LEN);
1068	wmb();
1069	strlcpy(tsk->comm, buf, sizeof(tsk->comm));
1070	task_unlock(tsk);
1071	perf_event_comm(tsk);
1072}
1073
1074int flush_old_exec(struct linux_binprm * bprm)
1075{
1076	int retval;
 
 
 
1077
1078	/*
1079	 * Make sure we have a private signal table and that
1080	 * we are unassociated from the previous thread group.
1081	 */
1082	retval = de_thread(current);
 
 
 
1083	if (retval)
1084		goto out;
1085
1086	set_mm_exe_file(bprm->mm, bprm->file);
 
 
 
 
 
 
 
 
 
 
 
 
1087
1088	/*
1089	 * Release all of the old mmap stuff
1090	 */
1091	acct_arg_size(bprm, 0);
1092	retval = exec_mmap(bprm->mm);
1093	if (retval)
1094		goto out;
1095
1096	bprm->mm = NULL;		/* We're using it now */
 
 
 
 
 
 
 
 
 
 
 
 
1097
1098	set_fs(USER_DS);
1099	current->flags &= ~(PF_RANDOMIZE | PF_KTHREAD);
 
 
 
 
 
 
 
1100	flush_thread();
1101	current->personality &= ~bprm->per_clear;
 
 
1102
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1103	return 0;
1104
 
 
 
 
 
1105out:
1106	return retval;
1107}
1108EXPORT_SYMBOL(flush_old_exec);
1109
1110void would_dump(struct linux_binprm *bprm, struct file *file)
1111{
1112	if (inode_permission(file->f_path.dentry->d_inode, MAY_READ) < 0)
 
 
 
1113		bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
 
 
 
 
 
 
 
 
 
 
 
 
1114}
1115EXPORT_SYMBOL(would_dump);
1116
1117void setup_new_exec(struct linux_binprm * bprm)
1118{
1119	int i, ch;
1120	const char *name;
1121	char tcomm[sizeof(current->comm)];
1122
1123	arch_pick_mmap_layout(current->mm);
1124
1125	/* This is the point of no return */
1126	current->sas_ss_sp = current->sas_ss_size = 0;
1127
1128	if (current_euid() == current_uid() && current_egid() == current_gid())
1129		set_dumpable(current->mm, 1);
1130	else
1131		set_dumpable(current->mm, suid_dumpable);
1132
1133	name = bprm->filename;
1134
1135	/* Copies the binary name from after last slash */
1136	for (i=0; (ch = *(name++)) != '\0';) {
1137		if (ch == '/')
1138			i = 0; /* overwrite what we wrote */
1139		else
1140			if (i < (sizeof(tcomm) - 1))
1141				tcomm[i++] = ch;
1142	}
1143	tcomm[i] = '\0';
1144	set_task_comm(current, tcomm);
1145
1146	/* Set the new mm task size. We have to do that late because it may
1147	 * depend on TIF_32BIT which is only updated in flush_thread() on
1148	 * some architectures like powerpc
1149	 */
1150	current->mm->task_size = TASK_SIZE;
1151
1152	/* install the new credentials */
1153	if (bprm->cred->uid != current_euid() ||
1154	    bprm->cred->gid != current_egid()) {
1155		current->pdeath_signal = 0;
1156	} else {
1157		would_dump(bprm, bprm->file);
1158		if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)
1159			set_dumpable(current->mm, suid_dumpable);
1160	}
1161
1162	/*
1163	 * Flush performance counters when crossing a
1164	 * security domain:
1165	 */
1166	if (!get_dumpable(current->mm))
1167		perf_event_exit_task(current);
1168
1169	/* An exec changes our domain. We are no longer part of the thread
1170	   group */
1171
1172	current->self_exec_id++;
1173			
1174	flush_signal_handlers(current, 0);
1175	flush_old_files(current->files);
1176}
1177EXPORT_SYMBOL(setup_new_exec);
1178
 
 
 
 
 
 
 
 
 
 
1179/*
1180 * Prepare credentials and lock ->cred_guard_mutex.
1181 * install_exec_creds() commits the new creds and drops the lock.
1182 * Or, if exec fails before, free_bprm() should release ->cred and
1183 * and unlock.
1184 */
1185int prepare_bprm_creds(struct linux_binprm *bprm)
1186{
1187	if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1188		return -ERESTARTNOINTR;
1189
1190	bprm->cred = prepare_exec_creds();
1191	if (likely(bprm->cred))
1192		return 0;
1193
1194	mutex_unlock(&current->signal->cred_guard_mutex);
1195	return -ENOMEM;
1196}
1197
1198void free_bprm(struct linux_binprm *bprm)
 
 
 
 
 
 
 
 
 
1199{
 
 
 
 
1200	free_arg_pages(bprm);
1201	if (bprm->cred) {
1202		mutex_unlock(&current->signal->cred_guard_mutex);
1203		abort_creds(bprm->cred);
1204	}
 
 
 
 
 
 
 
1205	kfree(bprm);
1206}
1207
1208/*
1209 * install the new credentials for this executable
1210 */
1211void install_exec_creds(struct linux_binprm *bprm)
1212{
1213	security_bprm_committing_creds(bprm);
 
 
1214
1215	commit_creds(bprm->cred);
1216	bprm->cred = NULL;
1217	/*
1218	 * cred_guard_mutex must be held at least to this point to prevent
1219	 * ptrace_attach() from altering our determination of the task's
1220	 * credentials; any time after this it may be unlocked.
1221	 */
1222	security_bprm_committed_creds(bprm);
1223	mutex_unlock(&current->signal->cred_guard_mutex);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1224}
1225EXPORT_SYMBOL(install_exec_creds);
 
 
 
 
 
 
 
 
 
 
 
1226
1227/*
1228 * determine how safe it is to execute the proposed program
1229 * - the caller must hold ->cred_guard_mutex to protect against
1230 *   PTRACE_ATTACH
1231 */
1232int check_unsafe_exec(struct linux_binprm *bprm)
1233{
1234	struct task_struct *p = current, *t;
1235	unsigned n_fs;
1236	int res = 0;
1237
1238	if (p->ptrace) {
1239		if (p->ptrace & PT_PTRACE_CAP)
1240			bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP;
1241		else
1242			bprm->unsafe |= LSM_UNSAFE_PTRACE;
1243	}
 
 
 
1244
 
 
 
 
 
 
1245	n_fs = 1;
1246	spin_lock(&p->fs->lock);
1247	rcu_read_lock();
1248	for (t = next_thread(p); t != p; t = next_thread(t)) {
1249		if (t->fs == p->fs)
1250			n_fs++;
1251	}
1252	rcu_read_unlock();
1253
1254	if (p->fs->users > n_fs) {
 
1255		bprm->unsafe |= LSM_UNSAFE_SHARE;
1256	} else {
1257		res = -EAGAIN;
1258		if (!p->fs->in_exec) {
1259			p->fs->in_exec = 1;
1260			res = 1;
1261		}
1262	}
1263	spin_unlock(&p->fs->lock);
1264
1265	return res;
1266}
1267
1268/* 
1269 * Fill the binprm structure from the inode. 
1270 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1271 *
1272 * This may be called multiple times for binary chains (scripts for example).
1273 */
1274int prepare_binprm(struct linux_binprm *bprm)
1275{
1276	umode_t mode;
1277	struct inode * inode = bprm->file->f_path.dentry->d_inode;
1278	int retval;
 
 
 
 
 
 
 
 
 
 
 
 
 
1279
 
 
 
 
 
 
1280	mode = inode->i_mode;
1281	if (bprm->file->f_op == NULL)
1282		return -EACCES;
 
 
 
 
 
 
1283
1284	/* clear any previous set[ug]id data from a previous binary */
1285	bprm->cred->euid = current_euid();
1286	bprm->cred->egid = current_egid();
1287
1288	if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1289		/* Set-uid? */
1290		if (mode & S_ISUID) {
1291			bprm->per_clear |= PER_CLEAR_ON_SETID;
1292			bprm->cred->euid = inode->i_uid;
1293		}
1294
1295		/* Set-gid? */
1296		/*
1297		 * If setgid is set but no group execute bit then this
1298		 * is a candidate for mandatory locking, not a setgid
1299		 * executable.
1300		 */
1301		if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1302			bprm->per_clear |= PER_CLEAR_ON_SETID;
1303			bprm->cred->egid = inode->i_gid;
1304		}
1305	}
 
1306
1307	/* fill in binprm security blob */
1308	retval = security_bprm_set_creds(bprm);
1309	if (retval)
1310		return retval;
1311	bprm->cred_prepared = 1;
 
 
1312
1313	memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1314	return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1315}
1316
1317EXPORT_SYMBOL(prepare_binprm);
 
 
 
 
 
 
 
 
 
 
 
 
1318
1319/*
1320 * Arguments are '\0' separated strings found at the location bprm->p
1321 * points to; chop off the first by relocating brpm->p to right after
1322 * the first '\0' encountered.
1323 */
1324int remove_arg_zero(struct linux_binprm *bprm)
1325{
1326	int ret = 0;
1327	unsigned long offset;
1328	char *kaddr;
1329	struct page *page;
1330
1331	if (!bprm->argc)
1332		return 0;
1333
1334	do {
1335		offset = bprm->p & ~PAGE_MASK;
1336		page = get_arg_page(bprm, bprm->p, 0);
1337		if (!page) {
1338			ret = -EFAULT;
1339			goto out;
1340		}
1341		kaddr = kmap_atomic(page, KM_USER0);
1342
1343		for (; offset < PAGE_SIZE && kaddr[offset];
1344				offset++, bprm->p++)
1345			;
1346
1347		kunmap_atomic(kaddr, KM_USER0);
1348		put_arg_page(page);
1349
1350		if (offset == PAGE_SIZE)
1351			free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1352	} while (offset == PAGE_SIZE);
1353
1354	bprm->p++;
1355	bprm->argc--;
1356	ret = 0;
1357
1358out:
1359	return ret;
1360}
1361EXPORT_SYMBOL(remove_arg_zero);
1362
 
1363/*
1364 * cycle the list of binary formats handler, until one recognizes the image
1365 */
1366int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1367{
1368	unsigned int depth = bprm->recursion_depth;
1369	int try,retval;
1370	struct linux_binfmt *fmt;
1371	pid_t old_pid;
1372
1373	retval = security_bprm_check(bprm);
1374	if (retval)
1375		return retval;
1376
1377	retval = audit_bprm(bprm);
1378	if (retval)
1379		return retval;
1380
1381	/* Need to fetch pid before load_binary changes it */
1382	rcu_read_lock();
1383	old_pid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1384	rcu_read_unlock();
1385
1386	retval = -ENOENT;
1387	for (try=0; try<2; try++) {
 
 
 
 
 
 
 
 
1388		read_lock(&binfmt_lock);
1389		list_for_each_entry(fmt, &formats, lh) {
1390			int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1391			if (!fn)
1392				continue;
1393			if (!try_module_get(fmt->module))
1394				continue;
1395			read_unlock(&binfmt_lock);
1396			retval = fn(bprm, regs);
1397			/*
1398			 * Restore the depth counter to its starting value
1399			 * in this call, so we don't have to rely on every
1400			 * load_binary function to restore it on return.
1401			 */
1402			bprm->recursion_depth = depth;
1403			if (retval >= 0) {
1404				if (depth == 0)
1405					ptrace_event(PTRACE_EVENT_EXEC,
1406							old_pid);
1407				put_binfmt(fmt);
1408				allow_write_access(bprm->file);
1409				if (bprm->file)
1410					fput(bprm->file);
1411				bprm->file = NULL;
1412				current->did_exec = 1;
1413				proc_exec_connector(current);
1414				return retval;
1415			}
1416			read_lock(&binfmt_lock);
1417			put_binfmt(fmt);
1418			if (retval != -ENOEXEC || bprm->mm == NULL)
1419				break;
1420			if (!bprm->file) {
1421				read_unlock(&binfmt_lock);
1422				return retval;
1423			}
1424		}
1425		read_unlock(&binfmt_lock);
1426#ifdef CONFIG_MODULES
1427		if (retval != -ENOEXEC || bprm->mm == NULL) {
1428			break;
1429		} else {
1430#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1431			if (printable(bprm->buf[0]) &&
1432			    printable(bprm->buf[1]) &&
1433			    printable(bprm->buf[2]) &&
1434			    printable(bprm->buf[3]))
1435				break; /* -ENOEXEC */
1436			if (try)
1437				break; /* -ENOEXEC */
1438			request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1439		}
1440#else
1441		break;
1442#endif
1443	}
 
 
 
 
 
 
 
 
 
 
 
 
1444	return retval;
1445}
1446
1447EXPORT_SYMBOL(search_binary_handler);
 
 
 
 
1448
1449/*
1450 * sys_execve() executes a new program.
1451 */
1452static int do_execve_common(const char *filename,
1453				struct user_arg_ptr argv,
1454				struct user_arg_ptr envp,
1455				struct pt_regs *regs)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1456{
1457	struct linux_binprm *bprm;
1458	struct file *file;
1459	struct files_struct *displaced;
1460	bool clear_in_exec;
1461	int retval;
1462	const struct cred *cred = current_cred();
 
 
1463
1464	/*
1465	 * We move the actual failure in case of RLIMIT_NPROC excess from
1466	 * set*uid() to execve() because too many poorly written programs
1467	 * don't check setuid() return code.  Here we additionally recheck
1468	 * whether NPROC limit is still exceeded.
1469	 */
1470	if ((current->flags & PF_NPROC_EXCEEDED) &&
1471	    atomic_read(&cred->user->processes) > rlimit(RLIMIT_NPROC)) {
1472		retval = -EAGAIN;
1473		goto out_ret;
1474	}
1475
1476	/* We're below the limit (still or again), so we don't want to make
1477	 * further execve() calls fail. */
1478	current->flags &= ~PF_NPROC_EXCEEDED;
1479
1480	retval = unshare_files(&displaced);
1481	if (retval)
 
1482		goto out_ret;
 
1483
1484	retval = -ENOMEM;
1485	bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1486	if (!bprm)
1487		goto out_files;
1488
1489	retval = prepare_bprm_creds(bprm);
1490	if (retval)
1491		goto out_free;
 
1492
1493	retval = check_unsafe_exec(bprm);
1494	if (retval < 0)
1495		goto out_free;
1496	clear_in_exec = retval;
1497	current->in_execve = 1;
1498
1499	file = open_exec(filename);
1500	retval = PTR_ERR(file);
1501	if (IS_ERR(file))
1502		goto out_unmark;
1503
1504	sched_exec();
1505
1506	bprm->file = file;
1507	bprm->filename = filename;
1508	bprm->interp = filename;
1509
1510	retval = bprm_mm_init(bprm);
1511	if (retval)
1512		goto out_file;
1513
1514	bprm->argc = count(argv, MAX_ARG_STRINGS);
1515	if ((retval = bprm->argc) < 0)
1516		goto out;
1517
1518	bprm->envc = count(envp, MAX_ARG_STRINGS);
1519	if ((retval = bprm->envc) < 0)
1520		goto out;
1521
1522	retval = prepare_binprm(bprm);
1523	if (retval < 0)
1524		goto out;
1525
1526	retval = copy_strings_kernel(1, &bprm->filename, bprm);
1527	if (retval < 0)
1528		goto out;
1529
1530	bprm->exec = bprm->p;
 
1531	retval = copy_strings(bprm->envc, envp, bprm);
1532	if (retval < 0)
1533		goto out;
1534
1535	retval = copy_strings(bprm->argc, argv, bprm);
1536	if (retval < 0)
1537		goto out;
1538
1539	retval = search_binary_handler(bprm,regs);
1540	if (retval < 0)
1541		goto out;
 
 
 
 
 
 
 
 
 
1542
1543	/* execve succeeded */
1544	current->fs->in_exec = 0;
1545	current->in_execve = 0;
1546	acct_update_integrals(current);
1547	free_bprm(bprm);
1548	if (displaced)
1549		put_files_struct(displaced);
 
1550	return retval;
 
1551
1552out:
1553	if (bprm->mm) {
1554		acct_arg_size(bprm, 0);
1555		mmput(bprm->mm);
1556	}
 
 
 
 
 
 
1557
1558out_file:
1559	if (bprm->file) {
1560		allow_write_access(bprm->file);
1561		fput(bprm->file);
 
 
 
 
1562	}
1563
1564out_unmark:
1565	if (clear_in_exec)
1566		current->fs->in_exec = 0;
1567	current->in_execve = 0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1568
 
 
 
 
 
 
 
 
 
1569out_free:
1570	free_bprm(bprm);
1571
1572out_files:
1573	if (displaced)
1574		reset_files_struct(displaced);
1575out_ret:
 
1576	return retval;
1577}
1578
1579int do_execve(const char *filename,
1580	const char __user *const __user *__argv,
1581	const char __user *const __user *__envp,
1582	struct pt_regs *regs)
1583{
1584	struct user_arg_ptr argv = { .ptr.native = __argv };
1585	struct user_arg_ptr envp = { .ptr.native = __envp };
1586	return do_execve_common(filename, argv, envp, regs);
 
 
 
 
 
 
 
 
 
 
 
1587}
1588
1589#ifdef CONFIG_COMPAT
1590int compat_do_execve(char *filename,
1591	compat_uptr_t __user *__argv,
1592	compat_uptr_t __user *__envp,
1593	struct pt_regs *regs)
1594{
1595	struct user_arg_ptr argv = {
1596		.is_compat = true,
1597		.ptr.compat = __argv,
1598	};
1599	struct user_arg_ptr envp = {
1600		.is_compat = true,
1601		.ptr.compat = __envp,
1602	};
1603	return do_execve_common(filename, argv, envp, regs);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1604}
1605#endif
1606
1607void set_binfmt(struct linux_binfmt *new)
1608{
1609	struct mm_struct *mm = current->mm;
1610
1611	if (mm->binfmt)
1612		module_put(mm->binfmt->module);
1613
1614	mm->binfmt = new;
1615	if (new)
1616		__module_get(new->module);
1617}
1618
1619EXPORT_SYMBOL(set_binfmt);
1620
1621static int expand_corename(struct core_name *cn)
1622{
1623	char *old_corename = cn->corename;
1624
1625	cn->size = CORENAME_MAX_SIZE * atomic_inc_return(&call_count);
1626	cn->corename = krealloc(old_corename, cn->size, GFP_KERNEL);
1627
1628	if (!cn->corename) {
1629		kfree(old_corename);
1630		return -ENOMEM;
1631	}
1632
1633	return 0;
1634}
1635
1636static int cn_printf(struct core_name *cn, const char *fmt, ...)
1637{
1638	char *cur;
1639	int need;
1640	int ret;
1641	va_list arg;
1642
1643	va_start(arg, fmt);
1644	need = vsnprintf(NULL, 0, fmt, arg);
1645	va_end(arg);
1646
1647	if (likely(need < cn->size - cn->used - 1))
1648		goto out_printf;
1649
1650	ret = expand_corename(cn);
1651	if (ret)
1652		goto expand_fail;
1653
1654out_printf:
1655	cur = cn->corename + cn->used;
1656	va_start(arg, fmt);
1657	vsnprintf(cur, need + 1, fmt, arg);
1658	va_end(arg);
1659	cn->used += need;
1660	return 0;
1661
1662expand_fail:
1663	return ret;
1664}
1665
1666static void cn_escape(char *str)
1667{
1668	for (; *str; str++)
1669		if (*str == '/')
1670			*str = '!';
1671}
1672
1673static int cn_print_exe_file(struct core_name *cn)
1674{
1675	struct file *exe_file;
1676	char *pathbuf, *path;
1677	int ret;
1678
1679	exe_file = get_mm_exe_file(current->mm);
1680	if (!exe_file) {
1681		char *commstart = cn->corename + cn->used;
1682		ret = cn_printf(cn, "%s (path unknown)", current->comm);
1683		cn_escape(commstart);
1684		return ret;
1685	}
1686
1687	pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY);
1688	if (!pathbuf) {
1689		ret = -ENOMEM;
1690		goto put_exe_file;
1691	}
1692
1693	path = d_path(&exe_file->f_path, pathbuf, PATH_MAX);
1694	if (IS_ERR(path)) {
1695		ret = PTR_ERR(path);
1696		goto free_buf;
1697	}
1698
1699	cn_escape(path);
1700
1701	ret = cn_printf(cn, "%s", path);
1702
1703free_buf:
1704	kfree(pathbuf);
1705put_exe_file:
1706	fput(exe_file);
1707	return ret;
1708}
1709
1710/* format_corename will inspect the pattern parameter, and output a
1711 * name into corename, which must have space for at least
1712 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1713 */
1714static int format_corename(struct core_name *cn, long signr)
1715{
1716	const struct cred *cred = current_cred();
1717	const char *pat_ptr = core_pattern;
1718	int ispipe = (*pat_ptr == '|');
1719	int pid_in_pattern = 0;
1720	int err = 0;
1721
1722	cn->size = CORENAME_MAX_SIZE * atomic_read(&call_count);
1723	cn->corename = kmalloc(cn->size, GFP_KERNEL);
1724	cn->used = 0;
1725
1726	if (!cn->corename)
1727		return -ENOMEM;
1728
1729	/* Repeat as long as we have more pattern to process and more output
1730	   space */
1731	while (*pat_ptr) {
1732		if (*pat_ptr != '%') {
1733			if (*pat_ptr == 0)
1734				goto out;
1735			err = cn_printf(cn, "%c", *pat_ptr++);
1736		} else {
1737			switch (*++pat_ptr) {
1738			/* single % at the end, drop that */
1739			case 0:
1740				goto out;
1741			/* Double percent, output one percent */
1742			case '%':
1743				err = cn_printf(cn, "%c", '%');
1744				break;
1745			/* pid */
1746			case 'p':
1747				pid_in_pattern = 1;
1748				err = cn_printf(cn, "%d",
1749					      task_tgid_vnr(current));
1750				break;
1751			/* uid */
1752			case 'u':
1753				err = cn_printf(cn, "%d", cred->uid);
1754				break;
1755			/* gid */
1756			case 'g':
1757				err = cn_printf(cn, "%d", cred->gid);
1758				break;
1759			/* signal that caused the coredump */
1760			case 's':
1761				err = cn_printf(cn, "%ld", signr);
1762				break;
1763			/* UNIX time of coredump */
1764			case 't': {
1765				struct timeval tv;
1766				do_gettimeofday(&tv);
1767				err = cn_printf(cn, "%lu", tv.tv_sec);
1768				break;
1769			}
1770			/* hostname */
1771			case 'h': {
1772				char *namestart = cn->corename + cn->used;
1773				down_read(&uts_sem);
1774				err = cn_printf(cn, "%s",
1775					      utsname()->nodename);
1776				up_read(&uts_sem);
1777				cn_escape(namestart);
1778				break;
1779			}
1780			/* executable */
1781			case 'e': {
1782				char *commstart = cn->corename + cn->used;
1783				err = cn_printf(cn, "%s", current->comm);
1784				cn_escape(commstart);
1785				break;
1786			}
1787			case 'E':
1788				err = cn_print_exe_file(cn);
1789				break;
1790			/* core limit size */
1791			case 'c':
1792				err = cn_printf(cn, "%lu",
1793					      rlimit(RLIMIT_CORE));
1794				break;
1795			default:
1796				break;
1797			}
1798			++pat_ptr;
1799		}
1800
1801		if (err)
1802			return err;
1803	}
1804
1805	/* Backward compatibility with core_uses_pid:
1806	 *
1807	 * If core_pattern does not include a %p (as is the default)
1808	 * and core_uses_pid is set, then .%pid will be appended to
1809	 * the filename. Do not do this for piped commands. */
1810	if (!ispipe && !pid_in_pattern && core_uses_pid) {
1811		err = cn_printf(cn, ".%d", task_tgid_vnr(current));
1812		if (err)
1813			return err;
1814	}
1815out:
1816	return ispipe;
1817}
1818
1819static int zap_process(struct task_struct *start, int exit_code)
1820{
1821	struct task_struct *t;
1822	int nr = 0;
1823
1824	start->signal->flags = SIGNAL_GROUP_EXIT;
1825	start->signal->group_exit_code = exit_code;
1826	start->signal->group_stop_count = 0;
1827
1828	t = start;
1829	do {
1830		task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1831		if (t != current && t->mm) {
1832			sigaddset(&t->pending.signal, SIGKILL);
1833			signal_wake_up(t, 1);
1834			nr++;
1835		}
1836	} while_each_thread(start, t);
1837
1838	return nr;
1839}
1840
1841static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1842				struct core_state *core_state, int exit_code)
1843{
1844	struct task_struct *g, *p;
1845	unsigned long flags;
1846	int nr = -EAGAIN;
1847
1848	spin_lock_irq(&tsk->sighand->siglock);
1849	if (!signal_group_exit(tsk->signal)) {
1850		mm->core_state = core_state;
1851		nr = zap_process(tsk, exit_code);
1852	}
1853	spin_unlock_irq(&tsk->sighand->siglock);
1854	if (unlikely(nr < 0))
1855		return nr;
1856
1857	if (atomic_read(&mm->mm_users) == nr + 1)
1858		goto done;
1859	/*
1860	 * We should find and kill all tasks which use this mm, and we should
1861	 * count them correctly into ->nr_threads. We don't take tasklist
1862	 * lock, but this is safe wrt:
1863	 *
1864	 * fork:
1865	 *	None of sub-threads can fork after zap_process(leader). All
1866	 *	processes which were created before this point should be
1867	 *	visible to zap_threads() because copy_process() adds the new
1868	 *	process to the tail of init_task.tasks list, and lock/unlock
1869	 *	of ->siglock provides a memory barrier.
1870	 *
1871	 * do_exit:
1872	 *	The caller holds mm->mmap_sem. This means that the task which
1873	 *	uses this mm can't pass exit_mm(), so it can't exit or clear
1874	 *	its ->mm.
1875	 *
1876	 * de_thread:
1877	 *	It does list_replace_rcu(&leader->tasks, &current->tasks),
1878	 *	we must see either old or new leader, this does not matter.
1879	 *	However, it can change p->sighand, so lock_task_sighand(p)
1880	 *	must be used. Since p->mm != NULL and we hold ->mmap_sem
1881	 *	it can't fail.
1882	 *
1883	 *	Note also that "g" can be the old leader with ->mm == NULL
1884	 *	and already unhashed and thus removed from ->thread_group.
1885	 *	This is OK, __unhash_process()->list_del_rcu() does not
1886	 *	clear the ->next pointer, we will find the new leader via
1887	 *	next_thread().
1888	 */
1889	rcu_read_lock();
1890	for_each_process(g) {
1891		if (g == tsk->group_leader)
1892			continue;
1893		if (g->flags & PF_KTHREAD)
1894			continue;
1895		p = g;
1896		do {
1897			if (p->mm) {
1898				if (unlikely(p->mm == mm)) {
1899					lock_task_sighand(p, &flags);
1900					nr += zap_process(p, exit_code);
1901					unlock_task_sighand(p, &flags);
1902				}
1903				break;
1904			}
1905		} while_each_thread(g, p);
1906	}
1907	rcu_read_unlock();
1908done:
1909	atomic_set(&core_state->nr_threads, nr);
1910	return nr;
1911}
1912
1913static int coredump_wait(int exit_code, struct core_state *core_state)
1914{
1915	struct task_struct *tsk = current;
1916	struct mm_struct *mm = tsk->mm;
1917	struct completion *vfork_done;
1918	int core_waiters = -EBUSY;
1919
1920	init_completion(&core_state->startup);
1921	core_state->dumper.task = tsk;
1922	core_state->dumper.next = NULL;
1923
1924	down_write(&mm->mmap_sem);
1925	if (!mm->core_state)
1926		core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1927	up_write(&mm->mmap_sem);
1928
1929	if (unlikely(core_waiters < 0))
1930		goto fail;
1931
1932	/*
1933	 * Make sure nobody is waiting for us to release the VM,
1934	 * otherwise we can deadlock when we wait on each other
1935	 */
1936	vfork_done = tsk->vfork_done;
1937	if (vfork_done) {
1938		tsk->vfork_done = NULL;
1939		complete(vfork_done);
1940	}
1941
1942	if (core_waiters)
1943		wait_for_completion(&core_state->startup);
1944fail:
1945	return core_waiters;
1946}
1947
1948static void coredump_finish(struct mm_struct *mm)
1949{
1950	struct core_thread *curr, *next;
1951	struct task_struct *task;
1952
1953	next = mm->core_state->dumper.next;
1954	while ((curr = next) != NULL) {
1955		next = curr->next;
1956		task = curr->task;
1957		/*
1958		 * see exit_mm(), curr->task must not see
1959		 * ->task == NULL before we read ->next.
1960		 */
1961		smp_mb();
1962		curr->task = NULL;
1963		wake_up_process(task);
1964	}
1965
1966	mm->core_state = NULL;
1967}
1968
1969/*
1970 * set_dumpable converts traditional three-value dumpable to two flags and
1971 * stores them into mm->flags.  It modifies lower two bits of mm->flags, but
1972 * these bits are not changed atomically.  So get_dumpable can observe the
1973 * intermediate state.  To avoid doing unexpected behavior, get get_dumpable
1974 * return either old dumpable or new one by paying attention to the order of
1975 * modifying the bits.
1976 *
1977 * dumpable |   mm->flags (binary)
1978 * old  new | initial interim  final
1979 * ---------+-----------------------
1980 *  0    1  |   00      01      01
1981 *  0    2  |   00      10(*)   11
1982 *  1    0  |   01      00      00
1983 *  1    2  |   01      11      11
1984 *  2    0  |   11      10(*)   00
1985 *  2    1  |   11      11      01
1986 *
1987 * (*) get_dumpable regards interim value of 10 as 11.
1988 */
1989void set_dumpable(struct mm_struct *mm, int value)
1990{
1991	switch (value) {
1992	case 0:
1993		clear_bit(MMF_DUMPABLE, &mm->flags);
1994		smp_wmb();
1995		clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1996		break;
1997	case 1:
1998		set_bit(MMF_DUMPABLE, &mm->flags);
1999		smp_wmb();
2000		clear_bit(MMF_DUMP_SECURELY, &mm->flags);
2001		break;
2002	case 2:
2003		set_bit(MMF_DUMP_SECURELY, &mm->flags);
2004		smp_wmb();
2005		set_bit(MMF_DUMPABLE, &mm->flags);
2006		break;
2007	}
2008}
2009
2010static int __get_dumpable(unsigned long mm_flags)
2011{
2012	int ret;
2013
2014	ret = mm_flags & MMF_DUMPABLE_MASK;
2015	return (ret >= 2) ? 2 : ret;
2016}
2017
2018int get_dumpable(struct mm_struct *mm)
 
 
 
2019{
2020	return __get_dumpable(mm->flags);
2021}
2022
2023static void wait_for_dump_helpers(struct file *file)
 
 
 
 
2024{
2025	struct pipe_inode_info *pipe;
2026
2027	pipe = file->f_path.dentry->d_inode->i_pipe;
2028
2029	pipe_lock(pipe);
2030	pipe->readers++;
2031	pipe->writers--;
2032
2033	while ((pipe->readers > 1) && (!signal_pending(current))) {
2034		wake_up_interruptible_sync(&pipe->wait);
2035		kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
2036		pipe_wait(pipe);
2037	}
2038
2039	pipe->readers--;
2040	pipe->writers++;
2041	pipe_unlock(pipe);
2042
2043}
2044
2045
2046/*
2047 * umh_pipe_setup
2048 * helper function to customize the process used
2049 * to collect the core in userspace.  Specifically
2050 * it sets up a pipe and installs it as fd 0 (stdin)
2051 * for the process.  Returns 0 on success, or
2052 * PTR_ERR on failure.
2053 * Note that it also sets the core limit to 1.  This
2054 * is a special value that we use to trap recursive
2055 * core dumps
2056 */
2057static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
2058{
2059	struct file *rp, *wp;
2060	struct fdtable *fdt;
2061	struct coredump_params *cp = (struct coredump_params *)info->data;
2062	struct files_struct *cf = current->files;
2063
2064	wp = create_write_pipe(0);
2065	if (IS_ERR(wp))
2066		return PTR_ERR(wp);
2067
2068	rp = create_read_pipe(wp, 0);
2069	if (IS_ERR(rp)) {
2070		free_write_pipe(wp);
2071		return PTR_ERR(rp);
2072	}
2073
2074	cp->file = wp;
2075
2076	sys_close(0);
2077	fd_install(0, rp);
2078	spin_lock(&cf->file_lock);
2079	fdt = files_fdtable(cf);
2080	FD_SET(0, fdt->open_fds);
2081	FD_CLR(0, fdt->close_on_exec);
2082	spin_unlock(&cf->file_lock);
2083
2084	/* and disallow core files too */
2085	current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
2086
2087	return 0;
2088}
 
2089
2090void do_coredump(long signr, int exit_code, struct pt_regs *regs)
2091{
2092	struct core_state core_state;
2093	struct core_name cn;
2094	struct mm_struct *mm = current->mm;
2095	struct linux_binfmt * binfmt;
2096	const struct cred *old_cred;
2097	struct cred *cred;
2098	int retval = 0;
2099	int flag = 0;
2100	int ispipe;
2101	static atomic_t core_dump_count = ATOMIC_INIT(0);
2102	struct coredump_params cprm = {
2103		.signr = signr,
2104		.regs = regs,
2105		.limit = rlimit(RLIMIT_CORE),
2106		/*
2107		 * We must use the same mm->flags while dumping core to avoid
2108		 * inconsistency of bit flags, since this flag is not protected
2109		 * by any locks.
2110		 */
2111		.mm_flags = mm->flags,
2112	};
2113
2114	audit_core_dumps(signr);
2115
2116	binfmt = mm->binfmt;
2117	if (!binfmt || !binfmt->core_dump)
2118		goto fail;
2119	if (!__get_dumpable(cprm.mm_flags))
2120		goto fail;
2121
2122	cred = prepare_creds();
2123	if (!cred)
2124		goto fail;
2125	/*
2126	 *	We cannot trust fsuid as being the "true" uid of the
2127	 *	process nor do we know its entire history. We only know it
2128	 *	was tainted so we dump it as root in mode 2.
2129	 */
2130	if (__get_dumpable(cprm.mm_flags) == 2) {
2131		/* Setuid core dump mode */
2132		flag = O_EXCL;		/* Stop rewrite attacks */
2133		cred->fsuid = 0;	/* Dump root private */
2134	}
2135
2136	retval = coredump_wait(exit_code, &core_state);
2137	if (retval < 0)
2138		goto fail_creds;
2139
2140	old_cred = override_creds(cred);
2141
2142	/*
2143	 * Clear any false indication of pending signals that might
2144	 * be seen by the filesystem code called to write the core file.
2145	 */
2146	clear_thread_flag(TIF_SIGPENDING);
2147
2148	ispipe = format_corename(&cn, signr);
2149
2150 	if (ispipe) {
2151		int dump_count;
2152		char **helper_argv;
2153
2154		if (ispipe < 0) {
2155			printk(KERN_WARNING "format_corename failed\n");
2156			printk(KERN_WARNING "Aborting core\n");
2157			goto fail_corename;
2158		}
2159
2160		if (cprm.limit == 1) {
2161			/*
2162			 * Normally core limits are irrelevant to pipes, since
2163			 * we're not writing to the file system, but we use
2164			 * cprm.limit of 1 here as a speacial value. Any
2165			 * non-1 limit gets set to RLIM_INFINITY below, but
2166			 * a limit of 0 skips the dump.  This is a consistent
2167			 * way to catch recursive crashes.  We can still crash
2168			 * if the core_pattern binary sets RLIM_CORE =  !1
2169			 * but it runs as root, and can do lots of stupid things
2170			 * Note that we use task_tgid_vnr here to grab the pid
2171			 * of the process group leader.  That way we get the
2172			 * right pid if a thread in a multi-threaded
2173			 * core_pattern process dies.
2174			 */
2175			printk(KERN_WARNING
2176				"Process %d(%s) has RLIMIT_CORE set to 1\n",
2177				task_tgid_vnr(current), current->comm);
2178			printk(KERN_WARNING "Aborting core\n");
2179			goto fail_unlock;
2180		}
2181		cprm.limit = RLIM_INFINITY;
2182
2183		dump_count = atomic_inc_return(&core_dump_count);
2184		if (core_pipe_limit && (core_pipe_limit < dump_count)) {
2185			printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
2186			       task_tgid_vnr(current), current->comm);
2187			printk(KERN_WARNING "Skipping core dump\n");
2188			goto fail_dropcount;
2189		}
2190
2191		helper_argv = argv_split(GFP_KERNEL, cn.corename+1, NULL);
2192		if (!helper_argv) {
2193			printk(KERN_WARNING "%s failed to allocate memory\n",
2194			       __func__);
2195			goto fail_dropcount;
2196		}
2197
2198		retval = call_usermodehelper_fns(helper_argv[0], helper_argv,
2199					NULL, UMH_WAIT_EXEC, umh_pipe_setup,
2200					NULL, &cprm);
2201		argv_free(helper_argv);
2202		if (retval) {
2203 			printk(KERN_INFO "Core dump to %s pipe failed\n",
2204			       cn.corename);
2205			goto close_fail;
2206 		}
2207	} else {
2208		struct inode *inode;
2209
2210		if (cprm.limit < binfmt->min_coredump)
2211			goto fail_unlock;
2212
2213		cprm.file = filp_open(cn.corename,
2214				 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
2215				 0600);
2216		if (IS_ERR(cprm.file))
2217			goto fail_unlock;
2218
2219		inode = cprm.file->f_path.dentry->d_inode;
2220		if (inode->i_nlink > 1)
2221			goto close_fail;
2222		if (d_unhashed(cprm.file->f_path.dentry))
2223			goto close_fail;
2224		/*
2225		 * AK: actually i see no reason to not allow this for named
2226		 * pipes etc, but keep the previous behaviour for now.
2227		 */
2228		if (!S_ISREG(inode->i_mode))
2229			goto close_fail;
2230		/*
2231		 * Dont allow local users get cute and trick others to coredump
2232		 * into their pre-created files.
2233		 */
2234		if (inode->i_uid != current_fsuid())
2235			goto close_fail;
2236		if (!cprm.file->f_op || !cprm.file->f_op->write)
2237			goto close_fail;
2238		if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
2239			goto close_fail;
2240	}
2241
2242	retval = binfmt->core_dump(&cprm);
2243	if (retval)
2244		current->signal->group_exit_code |= 0x80;
 
2245
2246	if (ispipe && core_pipe_limit)
2247		wait_for_dump_helpers(cprm.file);
2248close_fail:
2249	if (cprm.file)
2250		filp_close(cprm.file, NULL);
2251fail_dropcount:
2252	if (ispipe)
2253		atomic_dec(&core_dump_count);
2254fail_unlock:
2255	kfree(cn.corename);
2256fail_corename:
2257	coredump_finish(mm);
2258	revert_creds(old_cred);
2259fail_creds:
2260	put_cred(cred);
2261fail:
2262	return;
2263}
2264
2265/*
2266 * Core dumping helper functions.  These are the only things you should
2267 * do on a core-file: use only these functions to write out all the
2268 * necessary info.
2269 */
2270int dump_write(struct file *file, const void *addr, int nr)
2271{
2272	return access_ok(VERIFY_READ, addr, nr) && file->f_op->write(file, addr, nr, &file->f_pos) == nr;
 
2273}
2274EXPORT_SYMBOL(dump_write);
2275
2276int dump_seek(struct file *file, loff_t off)
2277{
2278	int ret = 1;
2279
2280	if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
2281		if (file->f_op->llseek(file, off, SEEK_CUR) < 0)
2282			return 0;
2283	} else {
2284		char *buf = (char *)get_zeroed_page(GFP_KERNEL);
2285
2286		if (!buf)
2287			return 0;
2288		while (off > 0) {
2289			unsigned long n = off;
2290
2291			if (n > PAGE_SIZE)
2292				n = PAGE_SIZE;
2293			if (!dump_write(file, buf, n)) {
2294				ret = 0;
2295				break;
2296			}
2297			off -= n;
2298		}
2299		free_page((unsigned long)buf);
2300	}
2301	return ret;
2302}
2303EXPORT_SYMBOL(dump_seek);