1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 *  linux/fs/exec.c
   4 *
   5 *  Copyright (C) 1991, 1992  Linus Torvalds
   6 */
   7
   8/*
   9 * #!-checking implemented by tytso.
  10 */
  11/*
  12 * Demand-loading implemented 01.12.91 - no need to read anything but
  13 * the header into memory. The inode of the executable is put into
  14 * "current->executable", and page faults do the actual loading. Clean.
  15 *
  16 * Once more I can proudly say that linux stood up to being changed: it
  17 * was less than 2 hours work to get demand-loading completely implemented.
  18 *
  19 * Demand loading changed July 1993 by Eric Youngdale.   Use mmap instead,
  20 * current->executable is only used by the procfs.  This allows a dispatch
  21 * table to check for several different types  of binary formats.  We keep
  22 * trying until we recognize the file or we run out of supported binary
  23 * formats.
  24 */
  25
  26#include <linux/kernel_read_file.h>
  27#include <linux/slab.h>
  28#include <linux/file.h>
  29#include <linux/fdtable.h>
  30#include <linux/mm.h>
 
  31#include <linux/stat.h>
  32#include <linux/fcntl.h>
  33#include <linux/swap.h>
  34#include <linux/string.h>
  35#include <linux/init.h>
  36#include <linux/sched/mm.h>
  37#include <linux/sched/coredump.h>
  38#include <linux/sched/signal.h>
  39#include <linux/sched/numa_balancing.h>
  40#include <linux/sched/task.h>
  41#include <linux/pagemap.h>
  42#include <linux/perf_event.h>
  43#include <linux/highmem.h>
  44#include <linux/spinlock.h>
  45#include <linux/key.h>
  46#include <linux/personality.h>
  47#include <linux/binfmts.h>
  48#include <linux/utsname.h>
  49#include <linux/pid_namespace.h>
  50#include <linux/module.h>
  51#include <linux/namei.h>
  52#include <linux/mount.h>
  53#include <linux/security.h>
  54#include <linux/syscalls.h>
  55#include <linux/tsacct_kern.h>
  56#include <linux/cn_proc.h>
  57#include <linux/audit.h>
 
  58#include <linux/kmod.h>
  59#include <linux/fsnotify.h>
  60#include <linux/fs_struct.h>
 
  61#include <linux/oom.h>
  62#include <linux/compat.h>
  63#include <linux/vmalloc.h>
  64#include <linux/io_uring.h>
  65#include <linux/syscall_user_dispatch.h>
  66#include <linux/coredump.h>
  67#include <linux/time_namespace.h>
  68#include <linux/user_events.h>
  69#include <linux/rseq.h>
  70
  71#include <linux/uaccess.h>
  72#include <asm/mmu_context.h>
  73#include <asm/tlb.h>
  74
  75#include <trace/events/task.h>
  76#include "internal.h"
  77
  78#include <trace/events/sched.h>
  79
  80static int bprm_creds_from_file(struct linux_binprm *bprm);
  81
  82int suid_dumpable = 0;
  83
  84static LIST_HEAD(formats);
  85static DEFINE_RWLOCK(binfmt_lock);
  86
  87void __register_binfmt(struct linux_binfmt * fmt, int insert)
  88{
 
 
 
  89	write_lock(&binfmt_lock);
  90	insert ? list_add(&fmt->lh, &formats) :
  91		 list_add_tail(&fmt->lh, &formats);
  92	write_unlock(&binfmt_lock);
  93}
  94
  95EXPORT_SYMBOL(__register_binfmt);
  96
  97void unregister_binfmt(struct linux_binfmt * fmt)
  98{
  99	write_lock(&binfmt_lock);
 100	list_del(&fmt->lh);
 101	write_unlock(&binfmt_lock);
 102}
 103
 104EXPORT_SYMBOL(unregister_binfmt);
 105
 106static inline void put_binfmt(struct linux_binfmt * fmt)
 107{
 108	module_put(fmt->module);
 109}
 110
 111bool path_noexec(const struct path *path)
 112{
 113	return (path->mnt->mnt_flags & MNT_NOEXEC) ||
 114	       (path->mnt->mnt_sb->s_iflags & SB_I_NOEXEC);
 115}
 116
 117#ifdef CONFIG_USELIB
 118/*
 119 * Note that a shared library must be both readable and executable due to
 120 * security reasons.
 121 *
 122 * Also note that we take the address to load from the file itself.
 123 */
 124SYSCALL_DEFINE1(uselib, const char __user *, library)
 125{
 126	struct linux_binfmt *fmt;
 127	struct file *file;
 128	struct filename *tmp = getname(library);
 129	int error = PTR_ERR(tmp);
 130	static const struct open_flags uselib_flags = {
 131		.open_flag = O_LARGEFILE | O_RDONLY,
 132		.acc_mode = MAY_READ | MAY_EXEC,
 133		.intent = LOOKUP_OPEN,
 134		.lookup_flags = LOOKUP_FOLLOW,
 135	};
 136
 137	if (IS_ERR(tmp))
 138		goto out;
 139
 140	file = do_filp_open(AT_FDCWD, tmp, &uselib_flags);
 141	putname(tmp);
 142	error = PTR_ERR(file);
 143	if (IS_ERR(file))
 144		goto out;
 145
 146	/*
 147	 * may_open() has already checked for this, so it should be
 148	 * impossible to trip now. But we need to be extra cautious
 149	 * and check again at the very end too.
 150	 */
 151	error = -EACCES;
 152	if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) ||
 153			 path_noexec(&file->f_path)))
 154		goto exit;
 155
 
 
 156	error = -ENOEXEC;
 157
 158	read_lock(&binfmt_lock);
 159	list_for_each_entry(fmt, &formats, lh) {
 160		if (!fmt->load_shlib)
 161			continue;
 162		if (!try_module_get(fmt->module))
 163			continue;
 164		read_unlock(&binfmt_lock);
 165		error = fmt->load_shlib(file);
 166		read_lock(&binfmt_lock);
 167		put_binfmt(fmt);
 168		if (error != -ENOEXEC)
 169			break;
 170	}
 171	read_unlock(&binfmt_lock);
 172exit:
 173	fput(file);
 174out:
 175	return error;
 176}
 177#endif /* #ifdef CONFIG_USELIB */
 178
 179#ifdef CONFIG_MMU
 180/*
 181 * The nascent bprm->mm is not visible until exec_mmap() but it can
 182 * use a lot of memory, account these pages in current->mm temporary
 183 * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
 184 * change the counter back via acct_arg_size(0).
 185 */
 186static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 187{
 188	struct mm_struct *mm = current->mm;
 189	long diff = (long)(pages - bprm->vma_pages);
 190
 191	if (!mm || !diff)
 192		return;
 193
 194	bprm->vma_pages = pages;
 195	add_mm_counter(mm, MM_ANONPAGES, diff);
 196}
 197
 198static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 199		int write)
 200{
 201	struct page *page;
 202	struct vm_area_struct *vma = bprm->vma;
 203	struct mm_struct *mm = bprm->mm;
 204	int ret;
 
 205
 206	/*
 207	 * Avoid relying on expanding the stack down in GUP (which
 208	 * does not work for STACK_GROWSUP anyway), and just do it
 209	 * by hand ahead of time.
 210	 */
 211	if (write && pos < vma->vm_start) {
 212		mmap_write_lock(mm);
 213		ret = expand_downwards(vma, pos);
 214		if (unlikely(ret < 0)) {
 215			mmap_write_unlock(mm);
 216			return NULL;
 217		}
 218		mmap_write_downgrade(mm);
 219	} else
 220		mmap_read_lock(mm);
 
 221
 222	/*
 223	 * We are doing an exec().  'current' is the process
 224	 * doing the exec and 'mm' is the new process's mm.
 225	 */
 226	ret = get_user_pages_remote(mm, pos, 1,
 227			write ? FOLL_WRITE : 0,
 228			&page, NULL);
 229	mmap_read_unlock(mm);
 230	if (ret <= 0)
 231		return NULL;
 232
 233	if (write)
 234		acct_arg_size(bprm, vma_pages(vma));
 235
 236	return page;
 237}
 238
 239static void put_arg_page(struct page *page)
 240{
 241	put_page(page);
 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 = vm_area_alloc(mm);
 261	if (!vma)
 262		return -ENOMEM;
 263	vma_set_anonymous(vma);
 264
 265	if (mmap_write_lock_killable(mm)) {
 266		err = -EINTR;
 267		goto err_free;
 268	}
 269
 270	/*
 271	 * Place the stack at the largest stack address the architecture
 272	 * supports. Later, we'll move this to an appropriate place. We don't
 273	 * use STACK_TOP because that can depend on attributes which aren't
 274	 * configured yet.
 275	 */
 276	BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
 277	vma->vm_end = STACK_TOP_MAX;
 278	vma->vm_start = vma->vm_end - PAGE_SIZE;
 279	vm_flags_init(vma, VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP);
 280	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 281
 282	err = insert_vm_struct(mm, vma);
 283	if (err)
 284		goto err;
 285
 286	mm->stack_vm = mm->total_vm = 1;
 287	mmap_write_unlock(mm);
 
 288	bprm->p = vma->vm_end - sizeof(void *);
 289	return 0;
 290err:
 291	mmap_write_unlock(mm);
 292err_free:
 293	bprm->vma = NULL;
 294	vm_area_free(vma);
 295	return err;
 296}
 297
 298static bool valid_arg_len(struct linux_binprm *bprm, long len)
 299{
 300	return len <= MAX_ARG_STRLEN;
 301}
 302
 303#else
 304
 305static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 306{
 307}
 308
 309static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 310		int write)
 311{
 312	struct page *page;
 313
 314	page = bprm->page[pos / PAGE_SIZE];
 315	if (!page && write) {
 316		page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
 317		if (!page)
 318			return NULL;
 319		bprm->page[pos / PAGE_SIZE] = page;
 320	}
 321
 322	return page;
 323}
 324
 325static void put_arg_page(struct page *page)
 326{
 327}
 328
 329static void free_arg_page(struct linux_binprm *bprm, int i)
 330{
 331	if (bprm->page[i]) {
 332		__free_page(bprm->page[i]);
 333		bprm->page[i] = NULL;
 334	}
 335}
 336
 337static void free_arg_pages(struct linux_binprm *bprm)
 338{
 339	int i;
 340
 341	for (i = 0; i < MAX_ARG_PAGES; i++)
 342		free_arg_page(bprm, i);
 343}
 344
 345static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 346		struct page *page)
 347{
 348}
 349
 350static int __bprm_mm_init(struct linux_binprm *bprm)
 351{
 352	bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
 353	return 0;
 354}
 355
 356static bool valid_arg_len(struct linux_binprm *bprm, long len)
 357{
 358	return len <= bprm->p;
 359}
 360
 361#endif /* CONFIG_MMU */
 362
 363/*
 364 * Create a new mm_struct and populate it with a temporary stack
 365 * vm_area_struct.  We don't have enough context at this point to set the stack
 366 * flags, permissions, and offset, so we use temporary values.  We'll update
 367 * them later in setup_arg_pages().
 368 */
 369static int bprm_mm_init(struct linux_binprm *bprm)
 370{
 371	int err;
 372	struct mm_struct *mm = NULL;
 373
 374	bprm->mm = mm = mm_alloc();
 375	err = -ENOMEM;
 376	if (!mm)
 377		goto err;
 378
 379	/* Save current stack limit for all calculations made during exec. */
 380	task_lock(current->group_leader);
 381	bprm->rlim_stack = current->signal->rlim[RLIMIT_STACK];
 382	task_unlock(current->group_leader);
 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		const 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			++i;
 452
 453			if (fatal_signal_pending(current))
 454				return -ERESTARTNOHAND;
 455			cond_resched();
 456		}
 457	}
 458	return i;
 459}
 460
 461static int count_strings_kernel(const char *const *argv)
 462{
 463	int i;
 464
 465	if (!argv)
 466		return 0;
 467
 468	for (i = 0; argv[i]; ++i) {
 469		if (i >= MAX_ARG_STRINGS)
 470			return -E2BIG;
 471		if (fatal_signal_pending(current))
 472			return -ERESTARTNOHAND;
 473		cond_resched();
 474	}
 475	return i;
 476}
 477
 478static int bprm_stack_limits(struct linux_binprm *bprm)
 479{
 480	unsigned long limit, ptr_size;
 481
 
 
 
 
 
 
 
 
 482	/*
 483	 * Limit to 1/4 of the max stack size or 3/4 of _STK_LIM
 484	 * (whichever is smaller) for the argv+env strings.
 485	 * This ensures that:
 486	 *  - the remaining binfmt code will not run out of stack space,
 487	 *  - the program will have a reasonable amount of stack left
 488	 *    to work from.
 489	 */
 490	limit = _STK_LIM / 4 * 3;
 491	limit = min(limit, bprm->rlim_stack.rlim_cur / 4);
 492	/*
 493	 * We've historically supported up to 32 pages (ARG_MAX)
 494	 * of argument strings even with small stacks
 495	 */
 496	limit = max_t(unsigned long, limit, ARG_MAX);
 497	/*
 498	 * We must account for the size of all the argv and envp pointers to
 499	 * the argv and envp strings, since they will also take up space in
 500	 * the stack. They aren't stored until much later when we can't
 501	 * signal to the parent that the child has run out of stack space.
 502	 * Instead, calculate it here so it's possible to fail gracefully.
 503	 *
 504	 * In the case of argc = 0, make sure there is space for adding a
 505	 * empty string (which will bump argc to 1), to ensure confused
 506	 * userspace programs don't start processing from argv[1], thinking
 507	 * argc can never be 0, to keep them from walking envp by accident.
 508	 * See do_execveat_common().
 509	 */
 510	ptr_size = (max(bprm->argc, 1) + bprm->envc) * sizeof(void *);
 511	if (limit <= ptr_size)
 512		return -E2BIG;
 513	limit -= ptr_size;
 514
 515	bprm->argmin = bprm->p - limit;
 516	return 0;
 517}
 518
 519/*
 520 * 'copy_strings()' copies argument/environment strings from the old
 521 * processes's memory to the new process's stack.  The call to get_user_pages()
 522 * ensures the destination page is created and not swapped out.
 523 */
 524static int copy_strings(int argc, struct user_arg_ptr argv,
 525			struct linux_binprm *bprm)
 526{
 527	struct page *kmapped_page = NULL;
 528	char *kaddr = NULL;
 529	unsigned long kpos = 0;
 530	int ret;
 531
 532	while (argc-- > 0) {
 533		const char __user *str;
 534		int len;
 535		unsigned long pos;
 536
 537		ret = -EFAULT;
 538		str = get_user_arg_ptr(argv, argc);
 539		if (IS_ERR(str))
 540			goto out;
 541
 542		len = strnlen_user(str, MAX_ARG_STRLEN);
 543		if (!len)
 544			goto out;
 545
 546		ret = -E2BIG;
 547		if (!valid_arg_len(bprm, len))
 548			goto out;
 549
 550		/* We're going to work our way backwards. */
 551		pos = bprm->p;
 552		str += len;
 553		bprm->p -= len;
 554#ifdef CONFIG_MMU
 555		if (bprm->p < bprm->argmin)
 556			goto out;
 557#endif
 558
 559		while (len > 0) {
 560			int offset, bytes_to_copy;
 561
 562			if (fatal_signal_pending(current)) {
 563				ret = -ERESTARTNOHAND;
 564				goto out;
 565			}
 566			cond_resched();
 567
 568			offset = pos % PAGE_SIZE;
 569			if (offset == 0)
 570				offset = PAGE_SIZE;
 571
 572			bytes_to_copy = offset;
 573			if (bytes_to_copy > len)
 574				bytes_to_copy = len;
 575
 576			offset -= bytes_to_copy;
 577			pos -= bytes_to_copy;
 578			str -= bytes_to_copy;
 579			len -= bytes_to_copy;
 580
 581			if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
 582				struct page *page;
 583
 584				page = get_arg_page(bprm, pos, 1);
 585				if (!page) {
 586					ret = -E2BIG;
 587					goto out;
 588				}
 589
 590				if (kmapped_page) {
 591					flush_dcache_page(kmapped_page);
 592					kunmap_local(kaddr);
 593					put_arg_page(kmapped_page);
 594				}
 595				kmapped_page = page;
 596				kaddr = kmap_local_page(kmapped_page);
 597				kpos = pos & PAGE_MASK;
 598				flush_arg_page(bprm, kpos, kmapped_page);
 599			}
 600			if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
 601				ret = -EFAULT;
 602				goto out;
 603			}
 604		}
 605	}
 606	ret = 0;
 607out:
 608	if (kmapped_page) {
 609		flush_dcache_page(kmapped_page);
 610		kunmap_local(kaddr);
 611		put_arg_page(kmapped_page);
 612	}
 613	return ret;
 614}
 615
 616/*
 617 * Copy and argument/environment string from the kernel to the processes stack.
 618 */
 619int copy_string_kernel(const char *arg, struct linux_binprm *bprm)
 
 620{
 621	int len = strnlen(arg, MAX_ARG_STRLEN) + 1 /* terminating NUL */;
 622	unsigned long pos = bprm->p;
 623
 624	if (len == 0)
 625		return -EFAULT;
 626	if (!valid_arg_len(bprm, len))
 627		return -E2BIG;
 628
 629	/* We're going to work our way backwards. */
 630	arg += len;
 631	bprm->p -= len;
 632	if (IS_ENABLED(CONFIG_MMU) && bprm->p < bprm->argmin)
 633		return -E2BIG;
 634
 635	while (len > 0) {
 636		unsigned int bytes_to_copy = min_t(unsigned int, len,
 637				min_not_zero(offset_in_page(pos), PAGE_SIZE));
 638		struct page *page;
 639
 640		pos -= bytes_to_copy;
 641		arg -= bytes_to_copy;
 642		len -= bytes_to_copy;
 643
 644		page = get_arg_page(bprm, pos, 1);
 645		if (!page)
 646			return -E2BIG;
 647		flush_arg_page(bprm, pos & PAGE_MASK, page);
 648		memcpy_to_page(page, offset_in_page(pos), arg, bytes_to_copy);
 649		put_arg_page(page);
 650	}
 651
 652	return 0;
 653}
 654EXPORT_SYMBOL(copy_string_kernel);
 655
 656static int copy_strings_kernel(int argc, const char *const *argv,
 657			       struct linux_binprm *bprm)
 658{
 659	while (argc-- > 0) {
 660		int ret = copy_string_kernel(argv[argc], bprm);
 661		if (ret < 0)
 662			return ret;
 663		if (fatal_signal_pending(current))
 664			return -ERESTARTNOHAND;
 665		cond_resched();
 666	}
 667	return 0;
 668}
 
 669
 670#ifdef CONFIG_MMU
 671
 672/*
 673 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 674 * the binfmt code determines where the new stack should reside, we shift it to
 675 * its final location.  The process proceeds as follows:
 676 *
 677 * 1) Use shift to calculate the new vma endpoints.
 678 * 2) Extend vma to cover both the old and new ranges.  This ensures the
 679 *    arguments passed to subsequent functions are consistent.
 680 * 3) Move vma's page tables to the new range.
 681 * 4) Free up any cleared pgd range.
 682 * 5) Shrink the vma to cover only the new range.
 683 */
 684static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 685{
 686	struct mm_struct *mm = vma->vm_mm;
 687	unsigned long old_start = vma->vm_start;
 688	unsigned long old_end = vma->vm_end;
 689	unsigned long length = old_end - old_start;
 690	unsigned long new_start = old_start - shift;
 691	unsigned long new_end = old_end - shift;
 692	VMA_ITERATOR(vmi, mm, new_start);
 693	struct vm_area_struct *next;
 694	struct mmu_gather tlb;
 695
 696	BUG_ON(new_start > new_end);
 697
 698	/*
 699	 * ensure there are no vmas between where we want to go
 700	 * and where we are
 701	 */
 702	if (vma != vma_next(&vmi))
 703		return -EFAULT;
 704
 705	vma_iter_prev_range(&vmi);
 706	/*
 707	 * cover the whole range: [new_start, old_end)
 708	 */
 709	if (vma_expand(&vmi, vma, new_start, old_end, vma->vm_pgoff, NULL))
 710		return -ENOMEM;
 711
 712	/*
 713	 * move the page tables downwards, on failure we rely on
 714	 * process cleanup to remove whatever mess we made.
 715	 */
 716	if (length != move_page_tables(vma, old_start,
 717				       vma, new_start, length, false, true))
 718		return -ENOMEM;
 719
 720	lru_add_drain();
 721	tlb_gather_mmu(&tlb, mm);
 722	next = vma_next(&vmi);
 723	if (new_end > old_start) {
 724		/*
 725		 * when the old and new regions overlap clear from new_end.
 726		 */
 727		free_pgd_range(&tlb, new_end, old_end, new_end,
 728			next ? next->vm_start : USER_PGTABLES_CEILING);
 729	} else {
 730		/*
 731		 * otherwise, clean from old_start; this is done to not touch
 732		 * the address space in [new_end, old_start) some architectures
 733		 * have constraints on va-space that make this illegal (IA64) -
 734		 * for the others its just a little faster.
 735		 */
 736		free_pgd_range(&tlb, old_start, old_end, new_end,
 737			next ? next->vm_start : USER_PGTABLES_CEILING);
 738	}
 739	tlb_finish_mmu(&tlb);
 
 
 
 
 
 740
 741	vma_prev(&vmi);
 742	/* Shrink the vma to just the new range */
 743	return vma_shrink(&vmi, vma, new_start, new_end, vma->vm_pgoff);
 744}
 745
 746/*
 747 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 748 * the stack is optionally relocated, and some extra space is added.
 749 */
 750int setup_arg_pages(struct linux_binprm *bprm,
 751		    unsigned long stack_top,
 752		    int executable_stack)
 753{
 754	unsigned long ret;
 755	unsigned long stack_shift;
 756	struct mm_struct *mm = current->mm;
 757	struct vm_area_struct *vma = bprm->vma;
 758	struct vm_area_struct *prev = NULL;
 759	unsigned long vm_flags;
 760	unsigned long stack_base;
 761	unsigned long stack_size;
 762	unsigned long stack_expand;
 763	unsigned long rlim_stack;
 764	struct mmu_gather tlb;
 765	struct vma_iterator vmi;
 766
 767#ifdef CONFIG_STACK_GROWSUP
 768	/* Limit stack size */
 769	stack_base = bprm->rlim_stack.rlim_max;
 770
 771	stack_base = calc_max_stack_size(stack_base);
 772
 773	/* Add space for stack randomization. */
 774	stack_base += (STACK_RND_MASK << PAGE_SHIFT);
 775
 776	/* Make sure we didn't let the argument array grow too large. */
 777	if (vma->vm_end - vma->vm_start > stack_base)
 778		return -ENOMEM;
 779
 780	stack_base = PAGE_ALIGN(stack_top - stack_base);
 781
 782	stack_shift = vma->vm_start - stack_base;
 783	mm->arg_start = bprm->p - stack_shift;
 784	bprm->p = vma->vm_end - stack_shift;
 785#else
 786	stack_top = arch_align_stack(stack_top);
 787	stack_top = PAGE_ALIGN(stack_top);
 788
 789	if (unlikely(stack_top < mmap_min_addr) ||
 790	    unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
 791		return -ENOMEM;
 792
 793	stack_shift = vma->vm_end - stack_top;
 794
 795	bprm->p -= stack_shift;
 796	mm->arg_start = bprm->p;
 797#endif
 798
 799	if (bprm->loader)
 800		bprm->loader -= stack_shift;
 801	bprm->exec -= stack_shift;
 802
 803	if (mmap_write_lock_killable(mm))
 804		return -EINTR;
 805
 806	vm_flags = VM_STACK_FLAGS;
 807
 808	/*
 809	 * Adjust stack execute permissions; explicitly enable for
 810	 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
 811	 * (arch default) otherwise.
 812	 */
 813	if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 814		vm_flags |= VM_EXEC;
 815	else if (executable_stack == EXSTACK_DISABLE_X)
 816		vm_flags &= ~VM_EXEC;
 817	vm_flags |= mm->def_flags;
 818	vm_flags |= VM_STACK_INCOMPLETE_SETUP;
 819
 820	vma_iter_init(&vmi, mm, vma->vm_start);
 821
 822	tlb_gather_mmu(&tlb, mm);
 823	ret = mprotect_fixup(&vmi, &tlb, vma, &prev, vma->vm_start, vma->vm_end,
 824			vm_flags);
 825	tlb_finish_mmu(&tlb);
 826
 827	if (ret)
 828		goto out_unlock;
 829	BUG_ON(prev != vma);
 830
 831	if (unlikely(vm_flags & VM_EXEC)) {
 832		pr_warn_once("process '%pD4' started with executable stack\n",
 833			     bprm->file);
 834	}
 835
 836	/* Move stack pages down in memory. */
 837	if (stack_shift) {
 838		ret = shift_arg_pages(vma, stack_shift);
 839		if (ret)
 840			goto out_unlock;
 841	}
 842
 843	/* mprotect_fixup is overkill to remove the temporary stack flags */
 844	vm_flags_clear(vma, VM_STACK_INCOMPLETE_SETUP);
 845
 846	stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
 847	stack_size = vma->vm_end - vma->vm_start;
 848	/*
 849	 * Align this down to a page boundary as expand_stack
 850	 * will align it up.
 851	 */
 852	rlim_stack = bprm->rlim_stack.rlim_cur & PAGE_MASK;
 853
 854	stack_expand = min(rlim_stack, stack_size + stack_expand);
 855
 856#ifdef CONFIG_STACK_GROWSUP
 857	stack_base = vma->vm_start + stack_expand;
 
 
 
 858#else
 859	stack_base = vma->vm_end - stack_expand;
 
 
 
 860#endif
 861	current->mm->start_stack = bprm->p;
 862	ret = expand_stack_locked(vma, stack_base);
 863	if (ret)
 864		ret = -EFAULT;
 865
 866out_unlock:
 867	mmap_write_unlock(mm);
 868	return ret;
 869}
 870EXPORT_SYMBOL(setup_arg_pages);
 871
 872#else
 873
 874/*
 875 * Transfer the program arguments and environment from the holding pages
 876 * onto the stack. The provided stack pointer is adjusted accordingly.
 877 */
 878int transfer_args_to_stack(struct linux_binprm *bprm,
 879			   unsigned long *sp_location)
 880{
 881	unsigned long index, stop, sp;
 882	int ret = 0;
 883
 884	stop = bprm->p >> PAGE_SHIFT;
 885	sp = *sp_location;
 886
 887	for (index = MAX_ARG_PAGES - 1; index >= stop; index--) {
 888		unsigned int offset = index == stop ? bprm->p & ~PAGE_MASK : 0;
 889		char *src = kmap_local_page(bprm->page[index]) + offset;
 890		sp -= PAGE_SIZE - offset;
 891		if (copy_to_user((void *) sp, src, PAGE_SIZE - offset) != 0)
 892			ret = -EFAULT;
 893		kunmap_local(src);
 894		if (ret)
 895			goto out;
 896	}
 897
 898	*sp_location = sp;
 899
 900out:
 901	return ret;
 902}
 903EXPORT_SYMBOL(transfer_args_to_stack);
 904
 905#endif /* CONFIG_MMU */
 906
 907/*
 908 * On success, caller must call do_close_execat() on the returned
 909 * struct file to close it.
 910 */
 911static struct file *do_open_execat(int fd, struct filename *name, int flags)
 912{
 913	struct file *file;
 914	int err;
 915	struct open_flags open_exec_flags = {
 916		.open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
 917		.acc_mode = MAY_EXEC,
 918		.intent = LOOKUP_OPEN,
 919		.lookup_flags = LOOKUP_FOLLOW,
 920	};
 921
 922	if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
 923		return ERR_PTR(-EINVAL);
 924	if (flags & AT_SYMLINK_NOFOLLOW)
 925		open_exec_flags.lookup_flags &= ~LOOKUP_FOLLOW;
 926	if (flags & AT_EMPTY_PATH)
 927		open_exec_flags.lookup_flags |= LOOKUP_EMPTY;
 928
 929	file = do_filp_open(fd, name, &open_exec_flags);
 930	if (IS_ERR(file))
 931		goto out;
 932
 933	/*
 934	 * may_open() has already checked for this, so it should be
 935	 * impossible to trip now. But we need to be extra cautious
 936	 * and check again at the very end too.
 937	 */
 938	err = -EACCES;
 939	if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) ||
 940			 path_noexec(&file->f_path)))
 
 
 941		goto exit;
 942
 943	err = deny_write_access(file);
 944	if (err)
 945		goto exit;
 946
 
 
 
 947out:
 948	return file;
 949
 950exit:
 951	fput(file);
 952	return ERR_PTR(err);
 953}
 954
 955/**
 956 * open_exec - Open a path name for execution
 957 *
 958 * @name: path name to open with the intent of executing it.
 959 *
 960 * Returns ERR_PTR on failure or allocated struct file on success.
 961 *
 962 * As this is a wrapper for the internal do_open_execat(), callers
 963 * must call allow_write_access() before fput() on release. Also see
 964 * do_close_execat().
 965 */
 966struct file *open_exec(const char *name)
 967{
 968	struct filename *filename = getname_kernel(name);
 969	struct file *f = ERR_CAST(filename);
 970
 971	if (!IS_ERR(filename)) {
 972		f = do_open_execat(AT_FDCWD, filename, 0);
 973		putname(filename);
 974	}
 975	return f;
 976}
 977EXPORT_SYMBOL(open_exec);
 978
 979#if defined(CONFIG_BINFMT_FLAT) || defined(CONFIG_BINFMT_ELF_FDPIC)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 980ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)
 981{
 982	ssize_t res = vfs_read(file, (void __user *)addr, len, &pos);
 983	if (res > 0)
 984		flush_icache_user_range(addr, addr + len);
 985	return res;
 986}
 987EXPORT_SYMBOL(read_code);
 988#endif
 989
 990/*
 991 * Maps the mm_struct mm into the current task struct.
 992 * On success, this function returns with exec_update_lock
 993 * held for writing.
 994 */
 995static int exec_mmap(struct mm_struct *mm)
 996{
 997	struct task_struct *tsk;
 998	struct mm_struct *old_mm, *active_mm;
 999	int ret;
1000
1001	/* Notify parent that we're no longer interested in the old VM */
1002	tsk = current;
1003	old_mm = current->mm;
1004	exec_mm_release(tsk, old_mm);
1005
1006	ret = down_write_killable(&tsk->signal->exec_update_lock);
1007	if (ret)
1008		return ret;
1009
1010	if (old_mm) {
 
1011		/*
1012		 * If there is a pending fatal signal perhaps a signal
1013		 * whose default action is to create a coredump get
1014		 * out and die instead of going through with the exec.
 
1015		 */
1016		ret = mmap_read_lock_killable(old_mm);
1017		if (ret) {
1018			up_write(&tsk->signal->exec_update_lock);
1019			return ret;
1020		}
1021	}
1022
1023	task_lock(tsk);
1024	membarrier_exec_mmap(mm);
1025
1026	local_irq_disable();
1027	active_mm = tsk->active_mm;
1028	tsk->active_mm = mm;
1029	tsk->mm = mm;
1030	mm_init_cid(mm);
1031	/*
1032	 * This prevents preemption while active_mm is being loaded and
1033	 * it and mm are being updated, which could cause problems for
1034	 * lazy tlb mm refcounting when these are updated by context
1035	 * switches. Not all architectures can handle irqs off over
1036	 * activate_mm yet.
1037	 */
1038	if (!IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM))
1039		local_irq_enable();
1040	activate_mm(active_mm, mm);
1041	if (IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM))
1042		local_irq_enable();
1043	lru_gen_add_mm(mm);
1044	task_unlock(tsk);
1045	lru_gen_use_mm(mm);
1046	if (old_mm) {
1047		mmap_read_unlock(old_mm);
1048		BUG_ON(active_mm != old_mm);
1049		setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm);
1050		mm_update_next_owner(old_mm);
1051		mmput(old_mm);
1052		return 0;
1053	}
1054	mmdrop_lazy_tlb(active_mm);
1055	return 0;
1056}
1057
 
 
 
 
 
 
1058static int de_thread(struct task_struct *tsk)
1059{
1060	struct signal_struct *sig = tsk->signal;
1061	struct sighand_struct *oldsighand = tsk->sighand;
1062	spinlock_t *lock = &oldsighand->siglock;
1063
1064	if (thread_group_empty(tsk))
1065		goto no_thread_group;
1066
1067	/*
1068	 * Kill all other threads in the thread group.
1069	 */
1070	spin_lock_irq(lock);
1071	if ((sig->flags & SIGNAL_GROUP_EXIT) || sig->group_exec_task) {
1072		/*
1073		 * Another group action in progress, just
1074		 * return so that the signal is processed.
1075		 */
1076		spin_unlock_irq(lock);
1077		return -EAGAIN;
1078	}
1079
1080	sig->group_exec_task = tsk;
1081	sig->notify_count = zap_other_threads(tsk);
1082	if (!thread_group_leader(tsk))
1083		sig->notify_count--;
1084
1085	while (sig->notify_count) {
1086		__set_current_state(TASK_KILLABLE);
1087		spin_unlock_irq(lock);
1088		schedule();
1089		if (__fatal_signal_pending(tsk))
1090			goto killed;
1091		spin_lock_irq(lock);
1092	}
1093	spin_unlock_irq(lock);
1094
1095	/*
1096	 * At this point all other threads have exited, all we have to
1097	 * do is to wait for the thread group leader to become inactive,
1098	 * and to assume its PID:
1099	 */
1100	if (!thread_group_leader(tsk)) {
1101		struct task_struct *leader = tsk->group_leader;
1102
1103		for (;;) {
1104			cgroup_threadgroup_change_begin(tsk);
1105			write_lock_irq(&tasklist_lock);
1106			/*
1107			 * Do this under tasklist_lock to ensure that
1108			 * exit_notify() can't miss ->group_exec_task
1109			 */
1110			sig->notify_count = -1;
1111			if (likely(leader->exit_state))
1112				break;
1113			__set_current_state(TASK_KILLABLE);
1114			write_unlock_irq(&tasklist_lock);
1115			cgroup_threadgroup_change_end(tsk);
1116			schedule();
1117			if (__fatal_signal_pending(tsk))
1118				goto killed;
1119		}
1120
1121		/*
1122		 * The only record we have of the real-time age of a
1123		 * process, regardless of execs it's done, is start_time.
1124		 * All the past CPU time is accumulated in signal_struct
1125		 * from sister threads now dead.  But in this non-leader
1126		 * exec, nothing survives from the original leader thread,
1127		 * whose birth marks the true age of this process now.
1128		 * When we take on its identity by switching to its PID, we
1129		 * also take its birthdate (always earlier than our own).
1130		 */
1131		tsk->start_time = leader->start_time;
1132		tsk->start_boottime = leader->start_boottime;
1133
1134		BUG_ON(!same_thread_group(leader, tsk));
 
1135		/*
1136		 * An exec() starts a new thread group with the
1137		 * TGID of the previous thread group. Rehash the
1138		 * two threads with a switched PID, and release
1139		 * the former thread group leader:
1140		 */
1141
1142		/* Become a process group leader with the old leader's pid.
1143		 * The old leader becomes a thread of the this thread group.
 
 
1144		 */
1145		exchange_tids(tsk, leader);
 
1146		transfer_pid(leader, tsk, PIDTYPE_TGID);
1147		transfer_pid(leader, tsk, PIDTYPE_PGID);
1148		transfer_pid(leader, tsk, PIDTYPE_SID);
1149
1150		list_replace_rcu(&leader->tasks, &tsk->tasks);
1151		list_replace_init(&leader->sibling, &tsk->sibling);
1152
1153		tsk->group_leader = tsk;
1154		leader->group_leader = tsk;
1155
1156		tsk->exit_signal = SIGCHLD;
1157		leader->exit_signal = -1;
1158
1159		BUG_ON(leader->exit_state != EXIT_ZOMBIE);
1160		leader->exit_state = EXIT_DEAD;
1161
1162		/*
1163		 * We are going to release_task()->ptrace_unlink() silently,
1164		 * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
1165		 * the tracer won't block again waiting for this thread.
1166		 */
1167		if (unlikely(leader->ptrace))
1168			__wake_up_parent(leader, leader->parent);
1169		write_unlock_irq(&tasklist_lock);
1170		cgroup_threadgroup_change_end(tsk);
1171
1172		release_task(leader);
1173	}
1174
1175	sig->group_exec_task = NULL;
1176	sig->notify_count = 0;
1177
1178no_thread_group:
1179	/* we have changed execution domain */
1180	tsk->exit_signal = SIGCHLD;
1181
1182	BUG_ON(!thread_group_leader(tsk));
1183	return 0;
1184
1185killed:
1186	/* protects against exit_notify() and __exit_signal() */
1187	read_lock(&tasklist_lock);
1188	sig->group_exec_task = NULL;
1189	sig->notify_count = 0;
1190	read_unlock(&tasklist_lock);
1191	return -EAGAIN;
1192}
1193
1194
1195/*
1196 * This function makes sure the current process has its own signal table,
1197 * so that flush_signal_handlers can later reset the handlers without
1198 * disturbing other processes.  (Other processes might share the signal
1199 * table via the CLONE_SIGHAND option to clone().)
1200 */
1201static int unshare_sighand(struct task_struct *me)
1202{
1203	struct sighand_struct *oldsighand = me->sighand;
1204
1205	if (refcount_read(&oldsighand->count) != 1) {
1206		struct sighand_struct *newsighand;
1207		/*
1208		 * This ->sighand is shared with the CLONE_SIGHAND
1209		 * but not CLONE_THREAD task, switch to the new one.
1210		 */
1211		newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1212		if (!newsighand)
1213			return -ENOMEM;
1214
1215		refcount_set(&newsighand->count, 1);
 
 
1216
1217		write_lock_irq(&tasklist_lock);
1218		spin_lock(&oldsighand->siglock);
1219		memcpy(newsighand->action, oldsighand->action,
1220		       sizeof(newsighand->action));
1221		rcu_assign_pointer(me->sighand, newsighand);
1222		spin_unlock(&oldsighand->siglock);
1223		write_unlock_irq(&tasklist_lock);
1224
1225		__cleanup_sighand(oldsighand);
1226	}
 
 
1227	return 0;
 
 
 
 
 
 
 
 
1228}
1229
1230char *__get_task_comm(char *buf, size_t buf_size, struct task_struct *tsk)
1231{
1232	task_lock(tsk);
1233	/* Always NUL terminated and zero-padded */
1234	strscpy_pad(buf, tsk->comm, buf_size);
1235	task_unlock(tsk);
1236	return buf;
1237}
1238EXPORT_SYMBOL_GPL(__get_task_comm);
1239
1240/*
1241 * These functions flushes out all traces of the currently running executable
1242 * so that a new one can be started
1243 */
1244
1245void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)
1246{
1247	task_lock(tsk);
1248	trace_task_rename(tsk, buf);
1249	strscpy_pad(tsk->comm, buf, sizeof(tsk->comm));
1250	task_unlock(tsk);
1251	perf_event_comm(tsk, exec);
1252}
1253
1254/*
1255 * Calling this is the point of no return. None of the failures will be
1256 * seen by userspace since either the process is already taking a fatal
1257 * signal (via de_thread() or coredump), or will have SEGV raised
1258 * (after exec_mmap()) by search_binary_handler (see below).
1259 */
1260int begin_new_exec(struct linux_binprm * bprm)
1261{
1262	struct task_struct *me = current;
1263	int retval;
1264
1265	/* Once we are committed compute the creds */
1266	retval = bprm_creds_from_file(bprm);
1267	if (retval)
1268		return retval;
1269
1270	/*
1271	 * Ensure all future errors are fatal.
 
1272	 */
1273	bprm->point_of_no_return = true;
1274
1275	/*
1276	 * Make this the only thread in the thread group.
1277	 */
1278	retval = de_thread(me);
1279	if (retval)
1280		goto out;
1281
1282	/*
1283	 * Cancel any io_uring activity across execve
1284	 */
1285	io_uring_task_cancel();
1286
1287	/* Ensure the files table is not shared. */
1288	retval = unshare_files();
1289	if (retval)
1290		goto out;
1291
1292	/*
1293	 * Must be called _before_ exec_mmap() as bprm->mm is
1294	 * not visible until then. Doing it here also ensures
1295	 * we don't race against replace_mm_exe_file().
1296	 */
1297	retval = set_mm_exe_file(bprm->mm, bprm->file);
1298	if (retval)
1299		goto out;
1300
1301	/* If the binary is not readable then enforce mm->dumpable=0 */
1302	would_dump(bprm, bprm->file);
1303	if (bprm->have_execfd)
1304		would_dump(bprm, bprm->executable);
1305
1306	/*
1307	 * Release all of the old mmap stuff
1308	 */
1309	acct_arg_size(bprm, 0);
1310	retval = exec_mmap(bprm->mm);
1311	if (retval)
1312		goto out;
1313
1314	bprm->mm = NULL;
1315
1316	retval = exec_task_namespaces();
1317	if (retval)
1318		goto out_unlock;
1319
1320#ifdef CONFIG_POSIX_TIMERS
1321	spin_lock_irq(&me->sighand->siglock);
1322	posix_cpu_timers_exit(me);
1323	spin_unlock_irq(&me->sighand->siglock);
1324	exit_itimers(me);
1325	flush_itimer_signals();
1326#endif
1327
1328	/*
1329	 * Make the signal table private.
 
 
 
1330	 */
1331	retval = unshare_sighand(me);
1332	if (retval)
1333		goto out_unlock;
1334
1335	me->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC |
 
1336					PF_NOFREEZE | PF_NO_SETAFFINITY);
1337	flush_thread();
1338	me->personality &= ~bprm->per_clear;
1339
1340	clear_syscall_work_syscall_user_dispatch(me);
1341
1342	/*
1343	 * We have to apply CLOEXEC before we change whether the process is
1344	 * dumpable (in setup_new_exec) to avoid a race with a process in userspace
1345	 * trying to access the should-be-closed file descriptors of a process
1346	 * undergoing exec(2).
1347	 */
1348	do_close_on_exec(me->files);
1349
1350	if (bprm->secureexec) {
1351		/* Make sure parent cannot signal privileged process. */
1352		me->pdeath_signal = 0;
1353
1354		/*
1355		 * For secureexec, reset the stack limit to sane default to
1356		 * avoid bad behavior from the prior rlimits. This has to
1357		 * happen before arch_pick_mmap_layout(), which examines
1358		 * RLIMIT_STACK, but after the point of no return to avoid
1359		 * needing to clean up the change on failure.
1360		 */
1361		if (bprm->rlim_stack.rlim_cur > _STK_LIM)
1362			bprm->rlim_stack.rlim_cur = _STK_LIM;
1363	}
1364
1365	me->sas_ss_sp = me->sas_ss_size = 0;
1366
1367	/*
1368	 * Figure out dumpability. Note that this checking only of current
1369	 * is wrong, but userspace depends on it. This should be testing
1370	 * bprm->secureexec instead.
1371	 */
1372	if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP ||
1373	    !(uid_eq(current_euid(), current_uid()) &&
1374	      gid_eq(current_egid(), current_gid())))
1375		set_dumpable(current->mm, suid_dumpable);
1376	else
1377		set_dumpable(current->mm, SUID_DUMP_USER);
1378
1379	perf_event_exec();
1380	__set_task_comm(me, kbasename(bprm->filename), true);
1381
1382	/* An exec changes our domain. We are no longer part of the thread
1383	   group */
1384	WRITE_ONCE(me->self_exec_id, me->self_exec_id + 1);
1385	flush_signal_handlers(me, 0);
1386
1387	retval = set_cred_ucounts(bprm->cred);
1388	if (retval < 0)
1389		goto out_unlock;
1390
1391	/*
1392	 * install the new credentials for this executable
1393	 */
1394	security_bprm_committing_creds(bprm);
1395
1396	commit_creds(bprm->cred);
1397	bprm->cred = NULL;
1398
1399	/*
1400	 * Disable monitoring for regular users
1401	 * when executing setuid binaries. Must
1402	 * wait until new credentials are committed
1403	 * by commit_creds() above
1404	 */
1405	if (get_dumpable(me->mm) != SUID_DUMP_USER)
1406		perf_event_exit_task(me);
1407	/*
1408	 * cred_guard_mutex must be held at least to this point to prevent
1409	 * ptrace_attach() from altering our determination of the task's
1410	 * credentials; any time after this it may be unlocked.
1411	 */
1412	security_bprm_committed_creds(bprm);
1413
1414	/* Pass the opened binary to the interpreter. */
1415	if (bprm->have_execfd) {
1416		retval = get_unused_fd_flags(0);
1417		if (retval < 0)
1418			goto out_unlock;
1419		fd_install(retval, bprm->executable);
1420		bprm->executable = NULL;
1421		bprm->execfd = retval;
1422	}
1423	return 0;
1424
1425out_unlock:
1426	up_write(&me->signal->exec_update_lock);
1427	if (!bprm->cred)
1428		mutex_unlock(&me->signal->cred_guard_mutex);
1429
1430out:
1431	return retval;
1432}
1433EXPORT_SYMBOL(begin_new_exec);
1434
1435void would_dump(struct linux_binprm *bprm, struct file *file)
1436{
1437	struct inode *inode = file_inode(file);
1438	struct mnt_idmap *idmap = file_mnt_idmap(file);
1439	if (inode_permission(idmap, inode, MAY_READ) < 0) {
1440		struct user_namespace *old, *user_ns;
1441		bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
1442
1443		/* Ensure mm->user_ns contains the executable */
1444		user_ns = old = bprm->mm->user_ns;
1445		while ((user_ns != &init_user_ns) &&
1446		       !privileged_wrt_inode_uidgid(user_ns, idmap, inode))
1447			user_ns = user_ns->parent;
1448
1449		if (old != user_ns) {
1450			bprm->mm->user_ns = get_user_ns(user_ns);
1451			put_user_ns(old);
1452		}
1453	}
1454}
1455EXPORT_SYMBOL(would_dump);
1456
1457void setup_new_exec(struct linux_binprm * bprm)
1458{
1459	/* Setup things that can depend upon the personality */
1460	struct task_struct *me = current;
 
 
 
 
1461
1462	arch_pick_mmap_layout(me->mm, &bprm->rlim_stack);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1463
1464	arch_setup_new_exec();
 
 
1465
1466	/* Set the new mm task size. We have to do that late because it may
1467	 * depend on TIF_32BIT which is only updated in flush_thread() on
1468	 * some architectures like powerpc
1469	 */
1470	me->mm->task_size = TASK_SIZE;
1471	up_write(&me->signal->exec_update_lock);
1472	mutex_unlock(&me->signal->cred_guard_mutex);
 
 
 
1473}
1474EXPORT_SYMBOL(setup_new_exec);
1475
1476/* Runs immediately before start_thread() takes over. */
1477void finalize_exec(struct linux_binprm *bprm)
1478{
1479	/* Store any stack rlimit changes before starting thread. */
1480	task_lock(current->group_leader);
1481	current->signal->rlim[RLIMIT_STACK] = bprm->rlim_stack;
1482	task_unlock(current->group_leader);
1483}
1484EXPORT_SYMBOL(finalize_exec);
1485
1486/*
1487 * Prepare credentials and lock ->cred_guard_mutex.
1488 * setup_new_exec() commits the new creds and drops the lock.
1489 * Or, if exec fails before, free_bprm() should release ->cred
1490 * and unlock.
1491 */
1492static int prepare_bprm_creds(struct linux_binprm *bprm)
1493{
1494	if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1495		return -ERESTARTNOINTR;
1496
1497	bprm->cred = prepare_exec_creds();
1498	if (likely(bprm->cred))
1499		return 0;
1500
1501	mutex_unlock(&current->signal->cred_guard_mutex);
1502	return -ENOMEM;
1503}
1504
1505/* Matches do_open_execat() */
1506static void do_close_execat(struct file *file)
1507{
1508	if (!file)
1509		return;
1510	allow_write_access(file);
1511	fput(file);
1512}
1513
1514static void free_bprm(struct linux_binprm *bprm)
1515{
1516	if (bprm->mm) {
1517		acct_arg_size(bprm, 0);
1518		mmput(bprm->mm);
1519	}
1520	free_arg_pages(bprm);
1521	if (bprm->cred) {
1522		mutex_unlock(&current->signal->cred_guard_mutex);
1523		abort_creds(bprm->cred);
1524	}
1525	do_close_execat(bprm->file);
1526	if (bprm->executable)
1527		fput(bprm->executable);
 
1528	/* If a binfmt changed the interp, free it. */
1529	if (bprm->interp != bprm->filename)
1530		kfree(bprm->interp);
1531	kfree(bprm->fdpath);
1532	kfree(bprm);
1533}
1534
1535static struct linux_binprm *alloc_bprm(int fd, struct filename *filename, int flags)
1536{
1537	struct linux_binprm *bprm;
1538	struct file *file;
1539	int retval = -ENOMEM;
1540
1541	file = do_open_execat(fd, filename, flags);
1542	if (IS_ERR(file))
1543		return ERR_CAST(file);
1544
1545	bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1546	if (!bprm) {
1547		do_close_execat(file);
1548		return ERR_PTR(-ENOMEM);
1549	}
1550
1551	bprm->file = file;
1552
1553	if (fd == AT_FDCWD || filename->name[0] == '/') {
1554		bprm->filename = filename->name;
1555	} else {
1556		if (filename->name[0] == '\0')
1557			bprm->fdpath = kasprintf(GFP_KERNEL, "/dev/fd/%d", fd);
1558		else
1559			bprm->fdpath = kasprintf(GFP_KERNEL, "/dev/fd/%d/%s",
1560						  fd, filename->name);
1561		if (!bprm->fdpath)
1562			goto out_free;
1563
1564		/*
1565		 * Record that a name derived from an O_CLOEXEC fd will be
1566		 * inaccessible after exec.  This allows the code in exec to
1567		 * choose to fail when the executable is not mmaped into the
1568		 * interpreter and an open file descriptor is not passed to
1569		 * the interpreter.  This makes for a better user experience
1570		 * than having the interpreter start and then immediately fail
1571		 * when it finds the executable is inaccessible.
1572		 */
1573		if (get_close_on_exec(fd))
1574			bprm->interp_flags |= BINPRM_FLAGS_PATH_INACCESSIBLE;
1575
1576		bprm->filename = bprm->fdpath;
1577	}
1578	bprm->interp = bprm->filename;
1579
1580	retval = bprm_mm_init(bprm);
1581	if (!retval)
1582		return bprm;
1583
1584out_free:
1585	free_bprm(bprm);
1586	return ERR_PTR(retval);
1587}
1588
1589int bprm_change_interp(const char *interp, struct linux_binprm *bprm)
1590{
1591	/* If a binfmt changed the interp, free it first. */
1592	if (bprm->interp != bprm->filename)
1593		kfree(bprm->interp);
1594	bprm->interp = kstrdup(interp, GFP_KERNEL);
1595	if (!bprm->interp)
1596		return -ENOMEM;
1597	return 0;
1598}
1599EXPORT_SYMBOL(bprm_change_interp);
1600
1601/*
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1602 * determine how safe it is to execute the proposed program
1603 * - the caller must hold ->cred_guard_mutex to protect against
1604 *   PTRACE_ATTACH or seccomp thread-sync
1605 */
1606static void check_unsafe_exec(struct linux_binprm *bprm)
1607{
1608	struct task_struct *p = current, *t;
1609	unsigned n_fs;
1610
1611	if (p->ptrace)
1612		bprm->unsafe |= LSM_UNSAFE_PTRACE;
1613
1614	/*
1615	 * This isn't strictly necessary, but it makes it harder for LSMs to
1616	 * mess up.
1617	 */
1618	if (task_no_new_privs(current))
1619		bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS;
1620
1621	/*
1622	 * If another task is sharing our fs, we cannot safely
1623	 * suid exec because the differently privileged task
1624	 * will be able to manipulate the current directory, etc.
1625	 * It would be nice to force an unshare instead...
1626	 */
1627	n_fs = 1;
1628	spin_lock(&p->fs->lock);
1629	rcu_read_lock();
1630	for_other_threads(p, t) {
1631		if (t->fs == p->fs)
1632			n_fs++;
1633	}
1634	rcu_read_unlock();
1635
1636	/* "users" and "in_exec" locked for copy_fs() */
1637	if (p->fs->users > n_fs)
1638		bprm->unsafe |= LSM_UNSAFE_SHARE;
1639	else
1640		p->fs->in_exec = 1;
1641	spin_unlock(&p->fs->lock);
1642}
1643
1644static void bprm_fill_uid(struct linux_binprm *bprm, struct file *file)
1645{
1646	/* Handle suid and sgid on files */
1647	struct mnt_idmap *idmap;
1648	struct inode *inode = file_inode(file);
1649	unsigned int mode;
1650	vfsuid_t vfsuid;
1651	vfsgid_t vfsgid;
 
 
 
 
 
 
 
 
 
1652
1653	if (!mnt_may_suid(file->f_path.mnt))
1654		return;
1655
1656	if (task_no_new_privs(current))
1657		return;
1658
 
1659	mode = READ_ONCE(inode->i_mode);
1660	if (!(mode & (S_ISUID|S_ISGID)))
1661		return;
1662
1663	idmap = file_mnt_idmap(file);
1664
1665	/* Be careful if suid/sgid is set */
1666	inode_lock(inode);
1667
1668	/* reload atomically mode/uid/gid now that lock held */
1669	mode = inode->i_mode;
1670	vfsuid = i_uid_into_vfsuid(idmap, inode);
1671	vfsgid = i_gid_into_vfsgid(idmap, inode);
1672	inode_unlock(inode);
1673
1674	/* We ignore suid/sgid if there are no mappings for them in the ns */
1675	if (!vfsuid_has_mapping(bprm->cred->user_ns, vfsuid) ||
1676	    !vfsgid_has_mapping(bprm->cred->user_ns, vfsgid))
1677		return;
1678
1679	if (mode & S_ISUID) {
1680		bprm->per_clear |= PER_CLEAR_ON_SETID;
1681		bprm->cred->euid = vfsuid_into_kuid(vfsuid);
1682	}
1683
1684	if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1685		bprm->per_clear |= PER_CLEAR_ON_SETID;
1686		bprm->cred->egid = vfsgid_into_kgid(vfsgid);
1687	}
1688}
1689
1690/*
1691 * Compute brpm->cred based upon the final binary.
1692 */
1693static int bprm_creds_from_file(struct linux_binprm *bprm)
1694{
1695	/* Compute creds based on which file? */
1696	struct file *file = bprm->execfd_creds ? bprm->executable : bprm->file;
1697
1698	bprm_fill_uid(bprm, file);
1699	return security_bprm_creds_from_file(bprm, file);
1700}
1701
1702/*
1703 * Fill the binprm structure from the inode.
1704 * Read the first BINPRM_BUF_SIZE bytes
1705 *
1706 * This may be called multiple times for binary chains (scripts for example).
1707 */
1708static int prepare_binprm(struct linux_binprm *bprm)
1709{
 
1710	loff_t pos = 0;
1711
 
 
 
 
 
 
 
 
1712	memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1713	return kernel_read(bprm->file, bprm->buf, BINPRM_BUF_SIZE, &pos);
1714}
1715
 
 
1716/*
1717 * Arguments are '\0' separated strings found at the location bprm->p
1718 * points to; chop off the first by relocating brpm->p to right after
1719 * the first '\0' encountered.
1720 */
1721int remove_arg_zero(struct linux_binprm *bprm)
1722{
1723	int ret = 0;
1724	unsigned long offset;
1725	char *kaddr;
1726	struct page *page;
1727
1728	if (!bprm->argc)
1729		return 0;
1730
1731	do {
1732		offset = bprm->p & ~PAGE_MASK;
1733		page = get_arg_page(bprm, bprm->p, 0);
1734		if (!page) {
1735			ret = -EFAULT;
1736			goto out;
1737		}
1738		kaddr = kmap_local_page(page);
1739
1740		for (; offset < PAGE_SIZE && kaddr[offset];
1741				offset++, bprm->p++)
1742			;
1743
1744		kunmap_local(kaddr);
1745		put_arg_page(page);
1746	} while (offset == PAGE_SIZE);
1747
1748	bprm->p++;
1749	bprm->argc--;
1750	ret = 0;
1751
1752out:
1753	return ret;
1754}
1755EXPORT_SYMBOL(remove_arg_zero);
1756
1757#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1758/*
1759 * cycle the list of binary formats handler, until one recognizes the image
1760 */
1761static int search_binary_handler(struct linux_binprm *bprm)
1762{
1763	bool need_retry = IS_ENABLED(CONFIG_MODULES);
1764	struct linux_binfmt *fmt;
1765	int retval;
1766
1767	retval = prepare_binprm(bprm);
1768	if (retval < 0)
1769		return retval;
1770
1771	retval = security_bprm_check(bprm);
1772	if (retval)
1773		return retval;
1774
1775	retval = -ENOENT;
1776 retry:
1777	read_lock(&binfmt_lock);
1778	list_for_each_entry(fmt, &formats, lh) {
1779		if (!try_module_get(fmt->module))
1780			continue;
1781		read_unlock(&binfmt_lock);
1782
 
1783		retval = fmt->load_binary(bprm);
 
1784
1785		read_lock(&binfmt_lock);
1786		put_binfmt(fmt);
1787		if (bprm->point_of_no_return || (retval != -ENOEXEC)) {
 
 
 
 
 
 
1788			read_unlock(&binfmt_lock);
1789			return retval;
1790		}
1791	}
1792	read_unlock(&binfmt_lock);
1793
1794	if (need_retry) {
1795		if (printable(bprm->buf[0]) && printable(bprm->buf[1]) &&
1796		    printable(bprm->buf[2]) && printable(bprm->buf[3]))
1797			return retval;
1798		if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0)
1799			return retval;
1800		need_retry = false;
1801		goto retry;
1802	}
1803
1804	return retval;
1805}
 
1806
1807/* binfmt handlers will call back into begin_new_exec() on success. */
1808static int exec_binprm(struct linux_binprm *bprm)
1809{
1810	pid_t old_pid, old_vpid;
1811	int ret, depth;
1812
1813	/* Need to fetch pid before load_binary changes it */
1814	old_pid = current->pid;
1815	rcu_read_lock();
1816	old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1817	rcu_read_unlock();
1818
1819	/* This allows 4 levels of binfmt rewrites before failing hard. */
1820	for (depth = 0;; depth++) {
1821		struct file *exec;
1822		if (depth > 5)
1823			return -ELOOP;
1824
1825		ret = search_binary_handler(bprm);
1826		if (ret < 0)
1827			return ret;
1828		if (!bprm->interpreter)
1829			break;
1830
1831		exec = bprm->file;
1832		bprm->file = bprm->interpreter;
1833		bprm->interpreter = NULL;
1834
1835		allow_write_access(exec);
1836		if (unlikely(bprm->have_execfd)) {
1837			if (bprm->executable) {
1838				fput(exec);
1839				return -ENOEXEC;
1840			}
1841			bprm->executable = exec;
1842		} else
1843			fput(exec);
1844	}
1845
1846	audit_bprm(bprm);
1847	trace_sched_process_exec(current, old_pid, bprm);
1848	ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
1849	proc_exec_connector(current);
1850	return 0;
1851}
1852
1853static int bprm_execve(struct linux_binprm *bprm)
1854{
1855	int retval;
1856
1857	retval = prepare_bprm_creds(bprm);
1858	if (retval)
1859		return retval;
1860
1861	/*
1862	 * Check for unsafe execution states before exec_binprm(), which
1863	 * will call back into begin_new_exec(), into bprm_creds_from_file(),
1864	 * where setuid-ness is evaluated.
1865	 */
1866	check_unsafe_exec(bprm);
1867	current->in_execve = 1;
1868	sched_mm_cid_before_execve(current);
1869
1870	sched_exec();
1871
1872	/* Set the unchanging part of bprm->cred */
1873	retval = security_bprm_creds_for_exec(bprm);
1874	if (retval)
1875		goto out;
1876
1877	retval = exec_binprm(bprm);
1878	if (retval < 0)
1879		goto out;
1880
1881	sched_mm_cid_after_execve(current);
1882	/* execve succeeded */
1883	current->fs->in_exec = 0;
1884	current->in_execve = 0;
1885	rseq_execve(current);
1886	user_events_execve(current);
1887	acct_update_integrals(current);
1888	task_numa_free(current, false);
1889	return retval;
1890
1891out:
1892	/*
1893	 * If past the point of no return ensure the code never
1894	 * returns to the userspace process.  Use an existing fatal
1895	 * signal if present otherwise terminate the process with
1896	 * SIGSEGV.
1897	 */
1898	if (bprm->point_of_no_return && !fatal_signal_pending(current))
1899		force_fatal_sig(SIGSEGV);
1900
1901	sched_mm_cid_after_execve(current);
1902	current->fs->in_exec = 0;
1903	current->in_execve = 0;
1904
1905	return retval;
1906}
1907
1908static int do_execveat_common(int fd, struct filename *filename,
1909			      struct user_arg_ptr argv,
1910			      struct user_arg_ptr envp,
1911			      int flags)
 
 
 
1912{
 
1913	struct linux_binprm *bprm;
 
1914	int retval;
1915
1916	if (IS_ERR(filename))
1917		return PTR_ERR(filename);
1918
1919	/*
1920	 * We move the actual failure in case of RLIMIT_NPROC excess from
1921	 * set*uid() to execve() because too many poorly written programs
1922	 * don't check setuid() return code.  Here we additionally recheck
1923	 * whether NPROC limit is still exceeded.
1924	 */
1925	if ((current->flags & PF_NPROC_EXCEEDED) &&
1926	    is_rlimit_overlimit(current_ucounts(), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) {
1927		retval = -EAGAIN;
1928		goto out_ret;
1929	}
1930
1931	/* We're below the limit (still or again), so we don't want to make
1932	 * further execve() calls fail. */
1933	current->flags &= ~PF_NPROC_EXCEEDED;
1934
1935	bprm = alloc_bprm(fd, filename, flags);
1936	if (IS_ERR(bprm)) {
1937		retval = PTR_ERR(bprm);
1938		goto out_ret;
1939	}
1940
1941	retval = count(argv, MAX_ARG_STRINGS);
1942	if (retval == 0)
1943		pr_warn_once("process '%s' launched '%s' with NULL argv: empty string added\n",
1944			     current->comm, bprm->filename);
1945	if (retval < 0)
 
 
1946		goto out_free;
1947	bprm->argc = retval;
1948
1949	retval = count(envp, MAX_ARG_STRINGS);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1950	if (retval < 0)
1951		goto out_free;
1952	bprm->envc = retval;
1953
1954	retval = bprm_stack_limits(bprm);
1955	if (retval < 0)
1956		goto out_free;
1957
1958	retval = copy_string_kernel(bprm->filename, bprm);
1959	if (retval < 0)
1960		goto out_free;
1961	bprm->exec = bprm->p;
1962
 
1963	retval = copy_strings(bprm->envc, envp, bprm);
1964	if (retval < 0)
1965		goto out_free;
1966
1967	retval = copy_strings(bprm->argc, argv, bprm);
1968	if (retval < 0)
1969		goto out_free;
1970
1971	/*
1972	 * When argv is empty, add an empty string ("") as argv[0] to
1973	 * ensure confused userspace programs that start processing
1974	 * from argv[1] won't end up walking envp. See also
1975	 * bprm_stack_limits().
1976	 */
1977	if (bprm->argc == 0) {
1978		retval = copy_string_kernel("", bprm);
1979		if (retval < 0)
1980			goto out_free;
1981		bprm->argc = 1;
 
 
 
 
 
 
 
 
 
 
 
 
 
1982	}
1983
1984	retval = bprm_execve(bprm);
 
 
 
1985out_free:
1986	free_bprm(bprm);
 
1987
 
 
 
1988out_ret:
1989	putname(filename);
 
1990	return retval;
1991}
1992
1993int kernel_execve(const char *kernel_filename,
1994		  const char *const *argv, const char *const *envp)
 
 
1995{
1996	struct filename *filename;
1997	struct linux_binprm *bprm;
1998	int fd = AT_FDCWD;
1999	int retval;
2000
2001	/* It is non-sense for kernel threads to call execve */
2002	if (WARN_ON_ONCE(current->flags & PF_KTHREAD))
2003		return -EINVAL;
2004
2005	filename = getname_kernel(kernel_filename);
2006	if (IS_ERR(filename))
2007		return PTR_ERR(filename);
2008
2009	bprm = alloc_bprm(fd, filename, 0);
2010	if (IS_ERR(bprm)) {
2011		retval = PTR_ERR(bprm);
2012		goto out_ret;
2013	}
2014
2015	retval = count_strings_kernel(argv);
2016	if (WARN_ON_ONCE(retval == 0))
2017		retval = -EINVAL;
2018	if (retval < 0)
2019		goto out_free;
2020	bprm->argc = retval;
2021
2022	retval = count_strings_kernel(envp);
2023	if (retval < 0)
2024		goto out_free;
2025	bprm->envc = retval;
2026
2027	retval = bprm_stack_limits(bprm);
2028	if (retval < 0)
2029		goto out_free;
2030
2031	retval = copy_string_kernel(bprm->filename, bprm);
2032	if (retval < 0)
2033		goto out_free;
2034	bprm->exec = bprm->p;
2035
2036	retval = copy_strings_kernel(bprm->envc, envp, bprm);
2037	if (retval < 0)
2038		goto out_free;
2039
2040	retval = copy_strings_kernel(bprm->argc, argv, bprm);
2041	if (retval < 0)
2042		goto out_free;
 
2043
2044	retval = bprm_execve(bprm);
2045out_free:
2046	free_bprm(bprm);
2047out_ret:
2048	putname(filename);
2049	return retval;
2050}
2051
2052static int do_execve(struct filename *filename,
2053	const char __user *const __user *__argv,
2054	const char __user *const __user *__envp)
2055{
2056	struct user_arg_ptr argv = { .ptr.native = __argv };
2057	struct user_arg_ptr envp = { .ptr.native = __envp };
2058	return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
2059}
2060
2061static int do_execveat(int fd, struct filename *filename,
2062		const char __user *const __user *__argv,
2063		const char __user *const __user *__envp,
2064		int flags)
2065{
2066	struct user_arg_ptr argv = { .ptr.native = __argv };
2067	struct user_arg_ptr envp = { .ptr.native = __envp };
2068
2069	return do_execveat_common(fd, filename, argv, envp, flags);
2070}
2071
2072#ifdef CONFIG_COMPAT
2073static int compat_do_execve(struct filename *filename,
2074	const compat_uptr_t __user *__argv,
2075	const compat_uptr_t __user *__envp)
2076{
2077	struct user_arg_ptr argv = {
2078		.is_compat = true,
2079		.ptr.compat = __argv,
2080	};
2081	struct user_arg_ptr envp = {
2082		.is_compat = true,
2083		.ptr.compat = __envp,
2084	};
2085	return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
2086}
2087
2088static int compat_do_execveat(int fd, struct filename *filename,
2089			      const compat_uptr_t __user *__argv,
2090			      const compat_uptr_t __user *__envp,
2091			      int flags)
2092{
2093	struct user_arg_ptr argv = {
2094		.is_compat = true,
2095		.ptr.compat = __argv,
2096	};
2097	struct user_arg_ptr envp = {
2098		.is_compat = true,
2099		.ptr.compat = __envp,
2100	};
2101	return do_execveat_common(fd, filename, argv, envp, flags);
2102}
2103#endif
2104
2105void set_binfmt(struct linux_binfmt *new)
2106{
2107	struct mm_struct *mm = current->mm;
2108
2109	if (mm->binfmt)
2110		module_put(mm->binfmt->module);
2111
2112	mm->binfmt = new;
2113	if (new)
2114		__module_get(new->module);
2115}
2116EXPORT_SYMBOL(set_binfmt);
2117
2118/*
2119 * set_dumpable stores three-value SUID_DUMP_* into mm->flags.
2120 */
2121void set_dumpable(struct mm_struct *mm, int value)
2122{
2123	if (WARN_ON((unsigned)value > SUID_DUMP_ROOT))
2124		return;
2125
2126	set_mask_bits(&mm->flags, MMF_DUMPABLE_MASK, value);
2127}
2128
2129SYSCALL_DEFINE3(execve,
2130		const char __user *, filename,
2131		const char __user *const __user *, argv,
2132		const char __user *const __user *, envp)
2133{
2134	return do_execve(getname(filename), argv, envp);
2135}
2136
2137SYSCALL_DEFINE5(execveat,
2138		int, fd, const char __user *, filename,
2139		const char __user *const __user *, argv,
2140		const char __user *const __user *, envp,
2141		int, flags)
2142{
 
 
2143	return do_execveat(fd,
2144			   getname_uflags(filename, flags),
2145			   argv, envp, flags);
2146}
2147
2148#ifdef CONFIG_COMPAT
2149COMPAT_SYSCALL_DEFINE3(execve, const char __user *, filename,
2150	const compat_uptr_t __user *, argv,
2151	const compat_uptr_t __user *, envp)
2152{
2153	return compat_do_execve(getname(filename), argv, envp);
2154}
2155
2156COMPAT_SYSCALL_DEFINE5(execveat, int, fd,
2157		       const char __user *, filename,
2158		       const compat_uptr_t __user *, argv,
2159		       const compat_uptr_t __user *, envp,
2160		       int,  flags)
2161{
 
 
2162	return compat_do_execveat(fd,
2163				  getname_uflags(filename, flags),
2164				  argv, envp, flags);
2165}
2166#endif
2167
2168#ifdef CONFIG_SYSCTL
2169
2170static int proc_dointvec_minmax_coredump(struct ctl_table *table, int write,
2171		void *buffer, size_t *lenp, loff_t *ppos)
2172{
2173	int error = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
2174
2175	if (!error)
2176		validate_coredump_safety();
2177	return error;
2178}
2179
2180static struct ctl_table fs_exec_sysctls[] = {
2181	{
2182		.procname	= "suid_dumpable",
2183		.data		= &suid_dumpable,
2184		.maxlen		= sizeof(int),
2185		.mode		= 0644,
2186		.proc_handler	= proc_dointvec_minmax_coredump,
2187		.extra1		= SYSCTL_ZERO,
2188		.extra2		= SYSCTL_TWO,
2189	},
2190};
2191
2192static int __init init_fs_exec_sysctls(void)
2193{
2194	register_sysctl_init("fs", fs_exec_sysctls);
2195	return 0;
2196}
2197
2198fs_initcall(init_fs_exec_sysctls);
2199#endif /* CONFIG_SYSCTL */