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
  69#include <linux/uaccess.h>
  70#include <asm/mmu_context.h>
  71#include <asm/tlb.h>
  72
  73#include <trace/events/task.h>
  74#include "internal.h"
  75
  76#include <trace/events/sched.h>
 
 
 
  77
  78static int bprm_creds_from_file(struct linux_binprm *bprm);
 
 
 
 
  79
  80int suid_dumpable = 0;
  81
  82static LIST_HEAD(formats);
  83static DEFINE_RWLOCK(binfmt_lock);
  84
  85void __register_binfmt(struct linux_binfmt * fmt, int insert)
  86{
 
 
  87	write_lock(&binfmt_lock);
  88	insert ? list_add(&fmt->lh, &formats) :
  89		 list_add_tail(&fmt->lh, &formats);
  90	write_unlock(&binfmt_lock);
 
  91}
  92
  93EXPORT_SYMBOL(__register_binfmt);
  94
  95void unregister_binfmt(struct linux_binfmt * fmt)
  96{
  97	write_lock(&binfmt_lock);
  98	list_del(&fmt->lh);
  99	write_unlock(&binfmt_lock);
 100}
 101
 102EXPORT_SYMBOL(unregister_binfmt);
 103
 104static inline void put_binfmt(struct linux_binfmt * fmt)
 105{
 106	module_put(fmt->module);
 107}
 108
 109bool path_noexec(const struct path *path)
 110{
 111	return (path->mnt->mnt_flags & MNT_NOEXEC) ||
 112	       (path->mnt->mnt_sb->s_iflags & SB_I_NOEXEC);
 113}
 114
 115#ifdef CONFIG_USELIB
 116/*
 117 * Note that a shared library must be both readable and executable due to
 118 * security reasons.
 119 *
 120 * Also note that we take the address to load from the file itself.
 121 */
 122SYSCALL_DEFINE1(uselib, const char __user *, library)
 123{
 124	struct linux_binfmt *fmt;
 125	struct file *file;
 126	struct filename *tmp = getname(library);
 127	int error = PTR_ERR(tmp);
 128	static const struct open_flags uselib_flags = {
 129		.open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
 130		.acc_mode = MAY_READ | MAY_EXEC,
 131		.intent = LOOKUP_OPEN,
 132		.lookup_flags = LOOKUP_FOLLOW,
 133	};
 134
 135	if (IS_ERR(tmp))
 136		goto out;
 137
 138	file = do_filp_open(AT_FDCWD, tmp, &uselib_flags);
 139	putname(tmp);
 140	error = PTR_ERR(file);
 141	if (IS_ERR(file))
 142		goto out;
 143
 144	/*
 145	 * may_open() has already checked for this, so it should be
 146	 * impossible to trip now. But we need to be extra cautious
 147	 * and check again at the very end too.
 148	 */
 149	error = -EACCES;
 150	if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) ||
 151			 path_noexec(&file->f_path)))
 152		goto exit;
 153
 154	fsnotify_open(file);
 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	int ret;
 203	unsigned int gup_flags = 0;
 204
 205#ifdef CONFIG_STACK_GROWSUP
 206	if (write) {
 207		ret = expand_downwards(bprm->vma, pos);
 208		if (ret < 0)
 209			return NULL;
 210	}
 211#endif
 212
 213	if (write)
 214		gup_flags |= FOLL_WRITE;
 215
 216	/*
 217	 * We are doing an exec().  'current' is the process
 218	 * doing the exec and bprm->mm is the new process's mm.
 219	 */
 220	mmap_read_lock(bprm->mm);
 221	ret = get_user_pages_remote(bprm->mm, pos, 1, gup_flags,
 222			&page, NULL, NULL);
 223	mmap_read_unlock(bprm->mm);
 224	if (ret <= 0)
 225		return NULL;
 226
 227	if (write)
 228		acct_arg_size(bprm, vma_pages(bprm->vma));
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 229
 230	return page;
 231}
 232
 233static void put_arg_page(struct page *page)
 234{
 235	put_page(page);
 236}
 237
 
 
 
 
 238static void free_arg_pages(struct linux_binprm *bprm)
 239{
 240}
 241
 242static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 243		struct page *page)
 244{
 245	flush_cache_page(bprm->vma, pos, page_to_pfn(page));
 246}
 247
 248static int __bprm_mm_init(struct linux_binprm *bprm)
 249{
 250	int err;
 251	struct vm_area_struct *vma = NULL;
 252	struct mm_struct *mm = bprm->mm;
 253
 254	bprm->vma = vma = vm_area_alloc(mm);
 255	if (!vma)
 256		return -ENOMEM;
 257	vma_set_anonymous(vma);
 258
 259	if (mmap_write_lock_killable(mm)) {
 260		err = -EINTR;
 261		goto err_free;
 262	}
 263
 264	/*
 265	 * Place the stack at the largest stack address the architecture
 266	 * supports. Later, we'll move this to an appropriate place. We don't
 267	 * use STACK_TOP because that can depend on attributes which aren't
 268	 * configured yet.
 269	 */
 270	BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
 271	vma->vm_end = STACK_TOP_MAX;
 272	vma->vm_start = vma->vm_end - PAGE_SIZE;
 273	vma->vm_flags = VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
 274	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 
 
 
 
 
 275
 276	err = insert_vm_struct(mm, vma);
 277	if (err)
 278		goto err;
 279
 280	mm->stack_vm = mm->total_vm = 1;
 281	mmap_write_unlock(mm);
 282	bprm->p = vma->vm_end - sizeof(void *);
 283	return 0;
 284err:
 285	mmap_write_unlock(mm);
 286err_free:
 287	bprm->vma = NULL;
 288	vm_area_free(vma);
 289	return err;
 290}
 291
 292static bool valid_arg_len(struct linux_binprm *bprm, long len)
 293{
 294	return len <= MAX_ARG_STRLEN;
 295}
 296
 297#else
 298
 299static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 300{
 301}
 302
 303static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 304		int write)
 305{
 306	struct page *page;
 307
 308	page = bprm->page[pos / PAGE_SIZE];
 309	if (!page && write) {
 310		page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
 311		if (!page)
 312			return NULL;
 313		bprm->page[pos / PAGE_SIZE] = page;
 314	}
 315
 316	return page;
 317}
 318
 319static void put_arg_page(struct page *page)
 320{
 321}
 322
 323static void free_arg_page(struct linux_binprm *bprm, int i)
 324{
 325	if (bprm->page[i]) {
 326		__free_page(bprm->page[i]);
 327		bprm->page[i] = NULL;
 328	}
 329}
 330
 331static void free_arg_pages(struct linux_binprm *bprm)
 332{
 333	int i;
 334
 335	for (i = 0; i < MAX_ARG_PAGES; i++)
 336		free_arg_page(bprm, i);
 337}
 338
 339static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 340		struct page *page)
 341{
 342}
 343
 344static int __bprm_mm_init(struct linux_binprm *bprm)
 345{
 346	bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
 347	return 0;
 348}
 349
 350static bool valid_arg_len(struct linux_binprm *bprm, long len)
 351{
 352	return len <= bprm->p;
 353}
 354
 355#endif /* CONFIG_MMU */
 356
 357/*
 358 * Create a new mm_struct and populate it with a temporary stack
 359 * vm_area_struct.  We don't have enough context at this point to set the stack
 360 * flags, permissions, and offset, so we use temporary values.  We'll update
 361 * them later in setup_arg_pages().
 362 */
 363static int bprm_mm_init(struct linux_binprm *bprm)
 364{
 365	int err;
 366	struct mm_struct *mm = NULL;
 367
 368	bprm->mm = mm = mm_alloc();
 369	err = -ENOMEM;
 370	if (!mm)
 371		goto err;
 372
 373	/* Save current stack limit for all calculations made during exec. */
 374	task_lock(current->group_leader);
 375	bprm->rlim_stack = current->signal->rlim[RLIMIT_STACK];
 376	task_unlock(current->group_leader);
 377
 378	err = __bprm_mm_init(bprm);
 379	if (err)
 380		goto err;
 381
 382	return 0;
 383
 384err:
 385	if (mm) {
 386		bprm->mm = NULL;
 387		mmdrop(mm);
 388	}
 389
 390	return err;
 391}
 392
 393struct user_arg_ptr {
 394#ifdef CONFIG_COMPAT
 395	bool is_compat;
 396#endif
 397	union {
 398		const char __user *const __user *native;
 399#ifdef CONFIG_COMPAT
 400		const compat_uptr_t __user *compat;
 401#endif
 402	} ptr;
 403};
 404
 405static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
 406{
 407	const char __user *native;
 408
 409#ifdef CONFIG_COMPAT
 410	if (unlikely(argv.is_compat)) {
 411		compat_uptr_t compat;
 412
 413		if (get_user(compat, argv.ptr.compat + nr))
 414			return ERR_PTR(-EFAULT);
 415
 416		return compat_ptr(compat);
 417	}
 418#endif
 419
 420	if (get_user(native, argv.ptr.native + nr))
 421		return ERR_PTR(-EFAULT);
 422
 423	return native;
 424}
 425
 426/*
 427 * count() counts the number of strings in array ARGV.
 428 */
 429static int count(struct user_arg_ptr argv, int max)
 430{
 431	int i = 0;
 432
 433	if (argv.ptr.native != NULL) {
 434		for (;;) {
 435			const char __user *p = get_user_arg_ptr(argv, i);
 436
 437			if (!p)
 438				break;
 439
 440			if (IS_ERR(p))
 441				return -EFAULT;
 442
 443			if (i >= max)
 444				return -E2BIG;
 445			++i;
 446
 447			if (fatal_signal_pending(current))
 448				return -ERESTARTNOHAND;
 449			cond_resched();
 450		}
 451	}
 452	return i;
 453}
 454
 455static int count_strings_kernel(const char *const *argv)
 456{
 457	int i;
 458
 459	if (!argv)
 460		return 0;
 461
 462	for (i = 0; argv[i]; ++i) {
 463		if (i >= MAX_ARG_STRINGS)
 464			return -E2BIG;
 465		if (fatal_signal_pending(current))
 466			return -ERESTARTNOHAND;
 467		cond_resched();
 468	}
 469	return i;
 470}
 471
 472static int bprm_stack_limits(struct linux_binprm *bprm)
 473{
 474	unsigned long limit, ptr_size;
 475
 476	/*
 477	 * Limit to 1/4 of the max stack size or 3/4 of _STK_LIM
 478	 * (whichever is smaller) for the argv+env strings.
 479	 * This ensures that:
 480	 *  - the remaining binfmt code will not run out of stack space,
 481	 *  - the program will have a reasonable amount of stack left
 482	 *    to work from.
 483	 */
 484	limit = _STK_LIM / 4 * 3;
 485	limit = min(limit, bprm->rlim_stack.rlim_cur / 4);
 486	/*
 487	 * We've historically supported up to 32 pages (ARG_MAX)
 488	 * of argument strings even with small stacks
 489	 */
 490	limit = max_t(unsigned long, limit, ARG_MAX);
 491	/*
 492	 * We must account for the size of all the argv and envp pointers to
 493	 * the argv and envp strings, since they will also take up space in
 494	 * the stack. They aren't stored until much later when we can't
 495	 * signal to the parent that the child has run out of stack space.
 496	 * Instead, calculate it here so it's possible to fail gracefully.
 497	 *
 498	 * In the case of argc = 0, make sure there is space for adding a
 499	 * empty string (which will bump argc to 1), to ensure confused
 500	 * userspace programs don't start processing from argv[1], thinking
 501	 * argc can never be 0, to keep them from walking envp by accident.
 502	 * See do_execveat_common().
 503	 */
 504	ptr_size = (max(bprm->argc, 1) + bprm->envc) * sizeof(void *);
 505	if (limit <= ptr_size)
 506		return -E2BIG;
 507	limit -= ptr_size;
 508
 509	bprm->argmin = bprm->p - limit;
 510	return 0;
 511}
 512
 513/*
 514 * 'copy_strings()' copies argument/environment strings from the old
 515 * processes's memory to the new process's stack.  The call to get_user_pages()
 516 * ensures the destination page is created and not swapped out.
 517 */
 518static int copy_strings(int argc, struct user_arg_ptr argv,
 519			struct linux_binprm *bprm)
 520{
 521	struct page *kmapped_page = NULL;
 522	char *kaddr = NULL;
 523	unsigned long kpos = 0;
 524	int ret;
 525
 526	while (argc-- > 0) {
 527		const char __user *str;
 528		int len;
 529		unsigned long pos;
 530
 531		ret = -EFAULT;
 532		str = get_user_arg_ptr(argv, argc);
 533		if (IS_ERR(str))
 534			goto out;
 535
 536		len = strnlen_user(str, MAX_ARG_STRLEN);
 537		if (!len)
 538			goto out;
 539
 540		ret = -E2BIG;
 541		if (!valid_arg_len(bprm, len))
 542			goto out;
 543
 544		/* We're going to work our way backwards. */
 545		pos = bprm->p;
 546		str += len;
 547		bprm->p -= len;
 548#ifdef CONFIG_MMU
 549		if (bprm->p < bprm->argmin)
 550			goto out;
 551#endif
 552
 553		while (len > 0) {
 554			int offset, bytes_to_copy;
 555
 556			if (fatal_signal_pending(current)) {
 557				ret = -ERESTARTNOHAND;
 558				goto out;
 559			}
 560			cond_resched();
 561
 562			offset = pos % PAGE_SIZE;
 563			if (offset == 0)
 564				offset = PAGE_SIZE;
 565
 566			bytes_to_copy = offset;
 567			if (bytes_to_copy > len)
 568				bytes_to_copy = len;
 569
 570			offset -= bytes_to_copy;
 571			pos -= bytes_to_copy;
 572			str -= bytes_to_copy;
 573			len -= bytes_to_copy;
 574
 575			if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
 576				struct page *page;
 577
 578				page = get_arg_page(bprm, pos, 1);
 579				if (!page) {
 580					ret = -E2BIG;
 581					goto out;
 582				}
 583
 584				if (kmapped_page) {
 585					flush_dcache_page(kmapped_page);
 586					kunmap_local(kaddr);
 587					put_arg_page(kmapped_page);
 588				}
 589				kmapped_page = page;
 590				kaddr = kmap_local_page(kmapped_page);
 591				kpos = pos & PAGE_MASK;
 592				flush_arg_page(bprm, kpos, kmapped_page);
 593			}
 594			if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
 595				ret = -EFAULT;
 596				goto out;
 597			}
 598		}
 599	}
 600	ret = 0;
 601out:
 602	if (kmapped_page) {
 603		flush_dcache_page(kmapped_page);
 604		kunmap_local(kaddr);
 605		put_arg_page(kmapped_page);
 606	}
 607	return ret;
 608}
 609
 610/*
 611 * Copy and argument/environment string from the kernel to the processes stack.
 612 */
 613int copy_string_kernel(const char *arg, struct linux_binprm *bprm)
 
 614{
 615	int len = strnlen(arg, MAX_ARG_STRLEN) + 1 /* terminating NUL */;
 616	unsigned long pos = bprm->p;
 617
 618	if (len == 0)
 619		return -EFAULT;
 620	if (!valid_arg_len(bprm, len))
 621		return -E2BIG;
 622
 623	/* We're going to work our way backwards. */
 624	arg += len;
 625	bprm->p -= len;
 626	if (IS_ENABLED(CONFIG_MMU) && bprm->p < bprm->argmin)
 627		return -E2BIG;
 628
 629	while (len > 0) {
 630		unsigned int bytes_to_copy = min_t(unsigned int, len,
 631				min_not_zero(offset_in_page(pos), PAGE_SIZE));
 632		struct page *page;
 633
 634		pos -= bytes_to_copy;
 635		arg -= bytes_to_copy;
 636		len -= bytes_to_copy;
 637
 638		page = get_arg_page(bprm, pos, 1);
 639		if (!page)
 640			return -E2BIG;
 641		flush_arg_page(bprm, pos & PAGE_MASK, page);
 642		memcpy_to_page(page, offset_in_page(pos), arg, bytes_to_copy);
 643		put_arg_page(page);
 644	}
 645
 646	return 0;
 647}
 648EXPORT_SYMBOL(copy_string_kernel);
 649
 650static int copy_strings_kernel(int argc, const char *const *argv,
 651			       struct linux_binprm *bprm)
 652{
 653	while (argc-- > 0) {
 654		int ret = copy_string_kernel(argv[argc], bprm);
 655		if (ret < 0)
 656			return ret;
 657		if (fatal_signal_pending(current))
 658			return -ERESTARTNOHAND;
 659		cond_resched();
 660	}
 661	return 0;
 662}
 
 663
 664#ifdef CONFIG_MMU
 665
 666/*
 667 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 668 * the binfmt code determines where the new stack should reside, we shift it to
 669 * its final location.  The process proceeds as follows:
 670 *
 671 * 1) Use shift to calculate the new vma endpoints.
 672 * 2) Extend vma to cover both the old and new ranges.  This ensures the
 673 *    arguments passed to subsequent functions are consistent.
 674 * 3) Move vma's page tables to the new range.
 675 * 4) Free up any cleared pgd range.
 676 * 5) Shrink the vma to cover only the new range.
 677 */
 678static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 679{
 680	struct mm_struct *mm = vma->vm_mm;
 681	unsigned long old_start = vma->vm_start;
 682	unsigned long old_end = vma->vm_end;
 683	unsigned long length = old_end - old_start;
 684	unsigned long new_start = old_start - shift;
 685	unsigned long new_end = old_end - shift;
 686	VMA_ITERATOR(vmi, mm, new_start);
 687	struct vm_area_struct *next;
 688	struct mmu_gather tlb;
 689
 690	BUG_ON(new_start > new_end);
 691
 692	/*
 693	 * ensure there are no vmas between where we want to go
 694	 * and where we are
 695	 */
 696	if (vma != vma_next(&vmi))
 697		return -EFAULT;
 698
 699	/*
 700	 * cover the whole range: [new_start, old_end)
 701	 */
 702	if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
 703		return -ENOMEM;
 704
 705	/*
 706	 * move the page tables downwards, on failure we rely on
 707	 * process cleanup to remove whatever mess we made.
 708	 */
 709	if (length != move_page_tables(vma, old_start,
 710				       vma, new_start, length, false))
 711		return -ENOMEM;
 712
 713	lru_add_drain();
 714	tlb_gather_mmu(&tlb, mm);
 715	next = vma_next(&vmi);
 716	if (new_end > old_start) {
 717		/*
 718		 * when the old and new regions overlap clear from new_end.
 719		 */
 720		free_pgd_range(&tlb, new_end, old_end, new_end,
 721			next ? next->vm_start : USER_PGTABLES_CEILING);
 722	} else {
 723		/*
 724		 * otherwise, clean from old_start; this is done to not touch
 725		 * the address space in [new_end, old_start) some architectures
 726		 * have constraints on va-space that make this illegal (IA64) -
 727		 * for the others its just a little faster.
 728		 */
 729		free_pgd_range(&tlb, old_start, old_end, new_end,
 730			next ? next->vm_start : USER_PGTABLES_CEILING);
 731	}
 732	tlb_finish_mmu(&tlb);
 733
 734	/*
 735	 * Shrink the vma to just the new range.  Always succeeds.
 736	 */
 737	vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
 738
 739	return 0;
 740}
 741
 742/*
 743 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 744 * the stack is optionally relocated, and some extra space is added.
 745 */
 746int setup_arg_pages(struct linux_binprm *bprm,
 747		    unsigned long stack_top,
 748		    int executable_stack)
 749{
 750	unsigned long ret;
 751	unsigned long stack_shift;
 752	struct mm_struct *mm = current->mm;
 753	struct vm_area_struct *vma = bprm->vma;
 754	struct vm_area_struct *prev = NULL;
 755	unsigned long vm_flags;
 756	unsigned long stack_base;
 757	unsigned long stack_size;
 758	unsigned long stack_expand;
 759	unsigned long rlim_stack;
 760	struct mmu_gather tlb;
 761
 762#ifdef CONFIG_STACK_GROWSUP
 763	/* Limit stack size */
 764	stack_base = bprm->rlim_stack.rlim_max;
 765
 766	stack_base = calc_max_stack_size(stack_base);
 767
 768	/* Add space for stack randomization. */
 769	stack_base += (STACK_RND_MASK << PAGE_SHIFT);
 770
 771	/* Make sure we didn't let the argument array grow too large. */
 772	if (vma->vm_end - vma->vm_start > stack_base)
 773		return -ENOMEM;
 774
 775	stack_base = PAGE_ALIGN(stack_top - stack_base);
 776
 777	stack_shift = vma->vm_start - stack_base;
 778	mm->arg_start = bprm->p - stack_shift;
 779	bprm->p = vma->vm_end - stack_shift;
 780#else
 781	stack_top = arch_align_stack(stack_top);
 782	stack_top = PAGE_ALIGN(stack_top);
 783
 784	if (unlikely(stack_top < mmap_min_addr) ||
 785	    unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
 786		return -ENOMEM;
 787
 788	stack_shift = vma->vm_end - stack_top;
 789
 790	bprm->p -= stack_shift;
 791	mm->arg_start = bprm->p;
 792#endif
 793
 794	if (bprm->loader)
 795		bprm->loader -= stack_shift;
 796	bprm->exec -= stack_shift;
 797
 798	if (mmap_write_lock_killable(mm))
 799		return -EINTR;
 800
 801	vm_flags = VM_STACK_FLAGS;
 802
 803	/*
 804	 * Adjust stack execute permissions; explicitly enable for
 805	 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
 806	 * (arch default) otherwise.
 807	 */
 808	if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 809		vm_flags |= VM_EXEC;
 810	else if (executable_stack == EXSTACK_DISABLE_X)
 811		vm_flags &= ~VM_EXEC;
 812	vm_flags |= mm->def_flags;
 813	vm_flags |= VM_STACK_INCOMPLETE_SETUP;
 814
 815	tlb_gather_mmu(&tlb, mm);
 816	ret = mprotect_fixup(&tlb, vma, &prev, vma->vm_start, vma->vm_end,
 817			vm_flags);
 818	tlb_finish_mmu(&tlb);
 819
 820	if (ret)
 821		goto out_unlock;
 822	BUG_ON(prev != vma);
 823
 824	if (unlikely(vm_flags & VM_EXEC)) {
 825		pr_warn_once("process '%pD4' started with executable stack\n",
 826			     bprm->file);
 827	}
 828
 829	/* Move stack pages down in memory. */
 830	if (stack_shift) {
 831		ret = shift_arg_pages(vma, stack_shift);
 832		if (ret)
 833			goto out_unlock;
 834	}
 835
 836	/* mprotect_fixup is overkill to remove the temporary stack flags */
 837	vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
 838
 839	stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
 840	stack_size = vma->vm_end - vma->vm_start;
 841	/*
 842	 * Align this down to a page boundary as expand_stack
 843	 * will align it up.
 844	 */
 845	rlim_stack = bprm->rlim_stack.rlim_cur & PAGE_MASK;
 846
 847	stack_expand = min(rlim_stack, stack_size + stack_expand);
 848
 849#ifdef CONFIG_STACK_GROWSUP
 850	stack_base = vma->vm_start + stack_expand;
 
 
 
 851#else
 852	stack_base = vma->vm_end - stack_expand;
 
 
 
 853#endif
 854	current->mm->start_stack = bprm->p;
 855	ret = expand_stack(vma, stack_base);
 856	if (ret)
 857		ret = -EFAULT;
 858
 859out_unlock:
 860	mmap_write_unlock(mm);
 861	return ret;
 862}
 863EXPORT_SYMBOL(setup_arg_pages);
 864
 865#else
 866
 867/*
 868 * Transfer the program arguments and environment from the holding pages
 869 * onto the stack. The provided stack pointer is adjusted accordingly.
 870 */
 871int transfer_args_to_stack(struct linux_binprm *bprm,
 872			   unsigned long *sp_location)
 873{
 874	unsigned long index, stop, sp;
 875	int ret = 0;
 876
 877	stop = bprm->p >> PAGE_SHIFT;
 878	sp = *sp_location;
 879
 880	for (index = MAX_ARG_PAGES - 1; index >= stop; index--) {
 881		unsigned int offset = index == stop ? bprm->p & ~PAGE_MASK : 0;
 882		char *src = kmap_local_page(bprm->page[index]) + offset;
 883		sp -= PAGE_SIZE - offset;
 884		if (copy_to_user((void *) sp, src, PAGE_SIZE - offset) != 0)
 885			ret = -EFAULT;
 886		kunmap_local(src);
 887		if (ret)
 888			goto out;
 889	}
 890
 891	*sp_location = sp;
 892
 893out:
 894	return ret;
 895}
 896EXPORT_SYMBOL(transfer_args_to_stack);
 897
 898#endif /* CONFIG_MMU */
 899
 900static struct file *do_open_execat(int fd, struct filename *name, int flags)
 901{
 902	struct file *file;
 903	int err;
 904	struct open_flags open_exec_flags = {
 905		.open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
 906		.acc_mode = MAY_EXEC,
 907		.intent = LOOKUP_OPEN,
 908		.lookup_flags = LOOKUP_FOLLOW,
 909	};
 910
 911	if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
 912		return ERR_PTR(-EINVAL);
 913	if (flags & AT_SYMLINK_NOFOLLOW)
 914		open_exec_flags.lookup_flags &= ~LOOKUP_FOLLOW;
 915	if (flags & AT_EMPTY_PATH)
 916		open_exec_flags.lookup_flags |= LOOKUP_EMPTY;
 917
 918	file = do_filp_open(fd, name, &open_exec_flags);
 919	if (IS_ERR(file))
 920		goto out;
 921
 922	/*
 923	 * may_open() has already checked for this, so it should be
 924	 * impossible to trip now. But we need to be extra cautious
 925	 * and check again at the very end too.
 926	 */
 927	err = -EACCES;
 928	if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) ||
 929			 path_noexec(&file->f_path)))
 
 
 930		goto exit;
 931
 
 
 932	err = deny_write_access(file);
 933	if (err)
 934		goto exit;
 935
 936	if (name->name[0] != '\0')
 937		fsnotify_open(file);
 938
 939out:
 940	return file;
 941
 942exit:
 943	fput(file);
 944	return ERR_PTR(err);
 945}
 946
 947struct file *open_exec(const char *name)
 948{
 949	struct filename *filename = getname_kernel(name);
 950	struct file *f = ERR_CAST(filename);
 951
 952	if (!IS_ERR(filename)) {
 953		f = do_open_execat(AT_FDCWD, filename, 0);
 954		putname(filename);
 955	}
 956	return f;
 957}
 958EXPORT_SYMBOL(open_exec);
 959
 960#if defined(CONFIG_BINFMT_FLAT) || defined(CONFIG_BINFMT_ELF_FDPIC)
 961ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)
 962{
 963	ssize_t res = vfs_read(file, (void __user *)addr, len, &pos);
 964	if (res > 0)
 965		flush_icache_user_range(addr, addr + len);
 966	return res;
 
 
 
 
 
 
 967}
 968EXPORT_SYMBOL(read_code);
 969#endif
 970
 971/*
 972 * Maps the mm_struct mm into the current task struct.
 973 * On success, this function returns with exec_update_lock
 974 * held for writing.
 975 */
 976static int exec_mmap(struct mm_struct *mm)
 977{
 978	struct task_struct *tsk;
 979	struct mm_struct *old_mm, *active_mm;
 980	int ret;
 981
 982	/* Notify parent that we're no longer interested in the old VM */
 983	tsk = current;
 984	old_mm = current->mm;
 985	exec_mm_release(tsk, old_mm);
 986	if (old_mm)
 987		sync_mm_rss(old_mm);
 988
 989	ret = down_write_killable(&tsk->signal->exec_update_lock);
 990	if (ret)
 991		return ret;
 992
 993	if (old_mm) {
 994		/*
 995		 * If there is a pending fatal signal perhaps a signal
 996		 * whose default action is to create a coredump get
 997		 * out and die instead of going through with the exec.
 
 998		 */
 999		ret = mmap_read_lock_killable(old_mm);
1000		if (ret) {
1001			up_write(&tsk->signal->exec_update_lock);
1002			return ret;
1003		}
1004	}
1005
1006	task_lock(tsk);
1007	membarrier_exec_mmap(mm);
1008
1009	local_irq_disable();
1010	active_mm = tsk->active_mm;
1011	tsk->active_mm = mm;
1012	tsk->mm = mm;
1013	/*
1014	 * This prevents preemption while active_mm is being loaded and
1015	 * it and mm are being updated, which could cause problems for
1016	 * lazy tlb mm refcounting when these are updated by context
1017	 * switches. Not all architectures can handle irqs off over
1018	 * activate_mm yet.
1019	 */
1020	if (!IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM))
1021		local_irq_enable();
1022	activate_mm(active_mm, mm);
1023	if (IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM))
1024		local_irq_enable();
1025	lru_gen_add_mm(mm);
 
1026	task_unlock(tsk);
1027	lru_gen_use_mm(mm);
1028	if (old_mm) {
1029		mmap_read_unlock(old_mm);
1030		BUG_ON(active_mm != old_mm);
1031		setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm);
1032		mm_update_next_owner(old_mm);
1033		mmput(old_mm);
1034		return 0;
1035	}
1036	mmdrop(active_mm);
1037	return 0;
1038}
1039
 
 
 
 
 
 
1040static int de_thread(struct task_struct *tsk)
1041{
1042	struct signal_struct *sig = tsk->signal;
1043	struct sighand_struct *oldsighand = tsk->sighand;
1044	spinlock_t *lock = &oldsighand->siglock;
1045
1046	if (thread_group_empty(tsk))
1047		goto no_thread_group;
1048
1049	/*
1050	 * Kill all other threads in the thread group.
1051	 */
1052	spin_lock_irq(lock);
1053	if ((sig->flags & SIGNAL_GROUP_EXIT) || sig->group_exec_task) {
1054		/*
1055		 * Another group action in progress, just
1056		 * return so that the signal is processed.
1057		 */
1058		spin_unlock_irq(lock);
1059		return -EAGAIN;
1060	}
1061
1062	sig->group_exec_task = tsk;
1063	sig->notify_count = zap_other_threads(tsk);
1064	if (!thread_group_leader(tsk))
1065		sig->notify_count--;
1066
1067	while (sig->notify_count) {
1068		__set_current_state(TASK_KILLABLE);
1069		spin_unlock_irq(lock);
1070		schedule();
1071		if (__fatal_signal_pending(tsk))
1072			goto killed;
1073		spin_lock_irq(lock);
1074	}
1075	spin_unlock_irq(lock);
1076
1077	/*
1078	 * At this point all other threads have exited, all we have to
1079	 * do is to wait for the thread group leader to become inactive,
1080	 * and to assume its PID:
1081	 */
1082	if (!thread_group_leader(tsk)) {
1083		struct task_struct *leader = tsk->group_leader;
1084
 
1085		for (;;) {
1086			cgroup_threadgroup_change_begin(tsk);
1087			write_lock_irq(&tasklist_lock);
1088			/*
1089			 * Do this under tasklist_lock to ensure that
1090			 * exit_notify() can't miss ->group_exec_task
1091			 */
1092			sig->notify_count = -1;
1093			if (likely(leader->exit_state))
1094				break;
1095			__set_current_state(TASK_KILLABLE);
1096			write_unlock_irq(&tasklist_lock);
1097			cgroup_threadgroup_change_end(tsk);
1098			schedule();
1099			if (__fatal_signal_pending(tsk))
1100				goto killed;
1101		}
1102
1103		/*
1104		 * The only record we have of the real-time age of a
1105		 * process, regardless of execs it's done, is start_time.
1106		 * All the past CPU time is accumulated in signal_struct
1107		 * from sister threads now dead.  But in this non-leader
1108		 * exec, nothing survives from the original leader thread,
1109		 * whose birth marks the true age of this process now.
1110		 * When we take on its identity by switching to its PID, we
1111		 * also take its birthdate (always earlier than our own).
1112		 */
1113		tsk->start_time = leader->start_time;
1114		tsk->start_boottime = leader->start_boottime;
1115
1116		BUG_ON(!same_thread_group(leader, tsk));
 
1117		/*
1118		 * An exec() starts a new thread group with the
1119		 * TGID of the previous thread group. Rehash the
1120		 * two threads with a switched PID, and release
1121		 * the former thread group leader:
1122		 */
1123
1124		/* Become a process group leader with the old leader's pid.
1125		 * The old leader becomes a thread of the this thread group.
 
 
1126		 */
1127		exchange_tids(tsk, leader);
1128		transfer_pid(leader, tsk, PIDTYPE_TGID);
 
1129		transfer_pid(leader, tsk, PIDTYPE_PGID);
1130		transfer_pid(leader, tsk, PIDTYPE_SID);
1131
1132		list_replace_rcu(&leader->tasks, &tsk->tasks);
1133		list_replace_init(&leader->sibling, &tsk->sibling);
1134
1135		tsk->group_leader = tsk;
1136		leader->group_leader = tsk;
1137
1138		tsk->exit_signal = SIGCHLD;
1139		leader->exit_signal = -1;
1140
1141		BUG_ON(leader->exit_state != EXIT_ZOMBIE);
1142		leader->exit_state = EXIT_DEAD;
1143
1144		/*
1145		 * We are going to release_task()->ptrace_unlink() silently,
1146		 * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
1147		 * the tracer won't block again waiting for this thread.
1148		 */
1149		if (unlikely(leader->ptrace))
1150			__wake_up_parent(leader, leader->parent);
1151		write_unlock_irq(&tasklist_lock);
1152		cgroup_threadgroup_change_end(tsk);
1153
1154		release_task(leader);
1155	}
1156
1157	sig->group_exec_task = NULL;
1158	sig->notify_count = 0;
1159
1160no_thread_group:
1161	/* we have changed execution domain */
1162	tsk->exit_signal = SIGCHLD;
1163
1164	BUG_ON(!thread_group_leader(tsk));
1165	return 0;
1166
1167killed:
1168	/* protects against exit_notify() and __exit_signal() */
1169	read_lock(&tasklist_lock);
1170	sig->group_exec_task = NULL;
1171	sig->notify_count = 0;
1172	read_unlock(&tasklist_lock);
1173	return -EAGAIN;
1174}
1175
1176
1177/*
1178 * This function makes sure the current process has its own signal table,
1179 * so that flush_signal_handlers can later reset the handlers without
1180 * disturbing other processes.  (Other processes might share the signal
1181 * table via the CLONE_SIGHAND option to clone().)
1182 */
1183static int unshare_sighand(struct task_struct *me)
1184{
1185	struct sighand_struct *oldsighand = me->sighand;
1186
1187	if (refcount_read(&oldsighand->count) != 1) {
1188		struct sighand_struct *newsighand;
1189		/*
1190		 * This ->sighand is shared with the CLONE_SIGHAND
1191		 * but not CLONE_THREAD task, switch to the new one.
1192		 */
1193		newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1194		if (!newsighand)
1195			return -ENOMEM;
1196
1197		refcount_set(&newsighand->count, 1);
 
 
1198
1199		write_lock_irq(&tasklist_lock);
1200		spin_lock(&oldsighand->siglock);
1201		memcpy(newsighand->action, oldsighand->action,
1202		       sizeof(newsighand->action));
1203		rcu_assign_pointer(me->sighand, newsighand);
1204		spin_unlock(&oldsighand->siglock);
1205		write_unlock_irq(&tasklist_lock);
1206
1207		__cleanup_sighand(oldsighand);
1208	}
1209	return 0;
1210}
1211
1212char *__get_task_comm(char *buf, size_t buf_size, struct task_struct *tsk)
1213{
1214	task_lock(tsk);
1215	/* Always NUL terminated and zero-padded */
1216	strscpy_pad(buf, tsk->comm, buf_size);
1217	task_unlock(tsk);
1218	return buf;
1219}
1220EXPORT_SYMBOL_GPL(__get_task_comm);
1221
1222/*
1223 * These functions flushes out all traces of the currently running executable
1224 * so that a new one can be started
1225 */
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1226
1227void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)
1228{
 
1229	task_lock(tsk);
1230	trace_task_rename(tsk, buf);
1231	strscpy_pad(tsk->comm, buf, sizeof(tsk->comm));
1232	task_unlock(tsk);
1233	perf_event_comm(tsk, exec);
1234}
 
1235
1236/*
1237 * Calling this is the point of no return. None of the failures will be
1238 * seen by userspace since either the process is already taking a fatal
1239 * signal (via de_thread() or coredump), or will have SEGV raised
1240 * (after exec_mmap()) by search_binary_handler (see below).
1241 */
1242int begin_new_exec(struct linux_binprm * bprm)
1243{
1244	struct task_struct *me = current;
1245	int retval;
1246
1247	/* Once we are committed compute the creds */
1248	retval = bprm_creds_from_file(bprm);
1249	if (retval)
1250		return retval;
1251
1252	/*
1253	 * Ensure all future errors are fatal.
1254	 */
1255	bprm->point_of_no_return = true;
1256
1257	/*
1258	 * Make this the only thread in the thread group.
1259	 */
1260	retval = de_thread(me);
1261	if (retval)
1262		goto out;
1263
1264	/*
1265	 * Cancel any io_uring activity across execve
1266	 */
1267	io_uring_task_cancel();
 
 
 
 
 
 
 
 
1268
1269	/* Ensure the files table is not shared. */
1270	retval = unshare_files();
1271	if (retval)
1272		goto out;
1273
1274	/*
1275	 * Must be called _before_ exec_mmap() as bprm->mm is
1276	 * not visible until then. This also enables the update
1277	 * to be lockless.
1278	 */
1279	retval = set_mm_exe_file(bprm->mm, bprm->file);
1280	if (retval)
1281		goto out;
1282
1283	/* If the binary is not readable then enforce mm->dumpable=0 */
1284	would_dump(bprm, bprm->file);
1285	if (bprm->have_execfd)
1286		would_dump(bprm, bprm->executable);
1287
1288	/*
1289	 * Release all of the old mmap stuff
1290	 */
1291	acct_arg_size(bprm, 0);
1292	retval = exec_mmap(bprm->mm);
1293	if (retval)
1294		goto out;
1295
1296	bprm->mm = NULL;
1297
1298	retval = exec_task_namespaces();
1299	if (retval)
1300		goto out_unlock;
1301
1302#ifdef CONFIG_POSIX_TIMERS
1303	spin_lock_irq(&me->sighand->siglock);
1304	posix_cpu_timers_exit(me);
1305	spin_unlock_irq(&me->sighand->siglock);
1306	exit_itimers(me);
1307	flush_itimer_signals();
1308#endif
1309
1310	/*
1311	 * Make the signal table private.
1312	 */
1313	retval = unshare_sighand(me);
1314	if (retval)
1315		goto out_unlock;
1316
1317	me->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC |
1318					PF_NOFREEZE | PF_NO_SETAFFINITY);
1319	flush_thread();
1320	me->personality &= ~bprm->per_clear;
1321
1322	clear_syscall_work_syscall_user_dispatch(me);
1323
1324	/*
1325	 * We have to apply CLOEXEC before we change whether the process is
1326	 * dumpable (in setup_new_exec) to avoid a race with a process in userspace
1327	 * trying to access the should-be-closed file descriptors of a process
1328	 * undergoing exec(2).
1329	 */
1330	do_close_on_exec(me->files);
1331
1332	if (bprm->secureexec) {
1333		/* Make sure parent cannot signal privileged process. */
1334		me->pdeath_signal = 0;
1335
1336		/*
1337		 * For secureexec, reset the stack limit to sane default to
1338		 * avoid bad behavior from the prior rlimits. This has to
1339		 * happen before arch_pick_mmap_layout(), which examines
1340		 * RLIMIT_STACK, but after the point of no return to avoid
1341		 * needing to clean up the change on failure.
1342		 */
1343		if (bprm->rlim_stack.rlim_cur > _STK_LIM)
1344			bprm->rlim_stack.rlim_cur = _STK_LIM;
1345	}
1346
1347	me->sas_ss_sp = me->sas_ss_size = 0;
1348
1349	/*
1350	 * Figure out dumpability. Note that this checking only of current
1351	 * is wrong, but userspace depends on it. This should be testing
1352	 * bprm->secureexec instead.
1353	 */
1354	if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP ||
1355	    !(uid_eq(current_euid(), current_uid()) &&
1356	      gid_eq(current_egid(), current_gid())))
1357		set_dumpable(current->mm, suid_dumpable);
1358	else
1359		set_dumpable(current->mm, SUID_DUMP_USER);
1360
1361	perf_event_exec();
1362	__set_task_comm(me, kbasename(bprm->filename), true);
1363
1364	/* An exec changes our domain. We are no longer part of the thread
1365	   group */
1366	WRITE_ONCE(me->self_exec_id, me->self_exec_id + 1);
1367	flush_signal_handlers(me, 0);
1368
1369	retval = set_cred_ucounts(bprm->cred);
1370	if (retval < 0)
1371		goto out_unlock;
1372
1373	/*
1374	 * install the new credentials for this executable
1375	 */
1376	security_bprm_committing_creds(bprm);
1377
1378	commit_creds(bprm->cred);
1379	bprm->cred = NULL;
1380
1381	/*
1382	 * Disable monitoring for regular users
1383	 * when executing setuid binaries. Must
1384	 * wait until new credentials are committed
1385	 * by commit_creds() above
1386	 */
1387	if (get_dumpable(me->mm) != SUID_DUMP_USER)
1388		perf_event_exit_task(me);
1389	/*
1390	 * cred_guard_mutex must be held at least to this point to prevent
1391	 * ptrace_attach() from altering our determination of the task's
1392	 * credentials; any time after this it may be unlocked.
1393	 */
1394	security_bprm_committed_creds(bprm);
1395
1396	/* Pass the opened binary to the interpreter. */
1397	if (bprm->have_execfd) {
1398		retval = get_unused_fd_flags(0);
1399		if (retval < 0)
1400			goto out_unlock;
1401		fd_install(retval, bprm->executable);
1402		bprm->executable = NULL;
1403		bprm->execfd = retval;
1404	}
1405	return 0;
1406
1407out_unlock:
1408	up_write(&me->signal->exec_update_lock);
1409out:
1410	return retval;
1411}
1412EXPORT_SYMBOL(begin_new_exec);
1413
1414void would_dump(struct linux_binprm *bprm, struct file *file)
1415{
1416	struct inode *inode = file_inode(file);
1417	struct user_namespace *mnt_userns = file_mnt_user_ns(file);
1418	if (inode_permission(mnt_userns, inode, MAY_READ) < 0) {
1419		struct user_namespace *old, *user_ns;
1420		bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
1421
1422		/* Ensure mm->user_ns contains the executable */
1423		user_ns = old = bprm->mm->user_ns;
1424		while ((user_ns != &init_user_ns) &&
1425		       !privileged_wrt_inode_uidgid(user_ns, mnt_userns, inode))
1426			user_ns = user_ns->parent;
1427
1428		if (old != user_ns) {
1429			bprm->mm->user_ns = get_user_ns(user_ns);
1430			put_user_ns(old);
1431		}
1432	}
1433}
1434EXPORT_SYMBOL(would_dump);
1435
1436void setup_new_exec(struct linux_binprm * bprm)
1437{
1438	/* Setup things that can depend upon the personality */
1439	struct task_struct *me = current;
 
1440
1441	arch_pick_mmap_layout(me->mm, &bprm->rlim_stack);
1442
1443	arch_setup_new_exec();
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1444
1445	/* Set the new mm task size. We have to do that late because it may
1446	 * depend on TIF_32BIT which is only updated in flush_thread() on
1447	 * some architectures like powerpc
1448	 */
1449	me->mm->task_size = TASK_SIZE;
1450	up_write(&me->signal->exec_update_lock);
1451	mutex_unlock(&me->signal->cred_guard_mutex);
1452}
1453EXPORT_SYMBOL(setup_new_exec);
1454
1455/* Runs immediately before start_thread() takes over. */
1456void finalize_exec(struct linux_binprm *bprm)
1457{
1458	/* Store any stack rlimit changes before starting thread. */
1459	task_lock(current->group_leader);
1460	current->signal->rlim[RLIMIT_STACK] = bprm->rlim_stack;
1461	task_unlock(current->group_leader);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1462}
1463EXPORT_SYMBOL(finalize_exec);
1464
1465/*
1466 * Prepare credentials and lock ->cred_guard_mutex.
1467 * setup_new_exec() commits the new creds and drops the lock.
1468 * Or, if exec fails before, free_bprm() should release ->cred
1469 * and unlock.
1470 */
1471static int prepare_bprm_creds(struct linux_binprm *bprm)
1472{
1473	if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1474		return -ERESTARTNOINTR;
1475
1476	bprm->cred = prepare_exec_creds();
1477	if (likely(bprm->cred))
1478		return 0;
1479
1480	mutex_unlock(&current->signal->cred_guard_mutex);
1481	return -ENOMEM;
1482}
1483
1484static void free_bprm(struct linux_binprm *bprm)
1485{
1486	if (bprm->mm) {
1487		acct_arg_size(bprm, 0);
1488		mmput(bprm->mm);
1489	}
1490	free_arg_pages(bprm);
1491	if (bprm->cred) {
1492		mutex_unlock(&current->signal->cred_guard_mutex);
1493		abort_creds(bprm->cred);
1494	}
1495	if (bprm->file) {
1496		allow_write_access(bprm->file);
1497		fput(bprm->file);
1498	}
1499	if (bprm->executable)
1500		fput(bprm->executable);
1501	/* If a binfmt changed the interp, free it. */
1502	if (bprm->interp != bprm->filename)
1503		kfree(bprm->interp);
1504	kfree(bprm->fdpath);
1505	kfree(bprm);
1506}
1507
1508static struct linux_binprm *alloc_bprm(int fd, struct filename *filename)
 
 
 
1509{
1510	struct linux_binprm *bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1511	int retval = -ENOMEM;
1512	if (!bprm)
1513		goto out;
1514
1515	if (fd == AT_FDCWD || filename->name[0] == '/') {
1516		bprm->filename = filename->name;
1517	} else {
1518		if (filename->name[0] == '\0')
1519			bprm->fdpath = kasprintf(GFP_KERNEL, "/dev/fd/%d", fd);
1520		else
1521			bprm->fdpath = kasprintf(GFP_KERNEL, "/dev/fd/%d/%s",
1522						  fd, filename->name);
1523		if (!bprm->fdpath)
1524			goto out_free;
1525
1526		bprm->filename = bprm->fdpath;
1527	}
1528	bprm->interp = bprm->filename;
1529
1530	retval = bprm_mm_init(bprm);
1531	if (retval)
1532		goto out_free;
1533	return bprm;
1534
1535out_free:
1536	free_bprm(bprm);
1537out:
1538	return ERR_PTR(retval);
1539}
1540
1541int bprm_change_interp(const char *interp, struct linux_binprm *bprm)
1542{
1543	/* If a binfmt changed the interp, free it first. */
1544	if (bprm->interp != bprm->filename)
1545		kfree(bprm->interp);
1546	bprm->interp = kstrdup(interp, GFP_KERNEL);
1547	if (!bprm->interp)
1548		return -ENOMEM;
1549	return 0;
1550}
1551EXPORT_SYMBOL(bprm_change_interp);
1552
1553/*
1554 * determine how safe it is to execute the proposed program
1555 * - the caller must hold ->cred_guard_mutex to protect against
1556 *   PTRACE_ATTACH or seccomp thread-sync
1557 */
1558static void check_unsafe_exec(struct linux_binprm *bprm)
1559{
1560	struct task_struct *p = current, *t;
1561	unsigned n_fs;
 
1562
1563	if (p->ptrace)
1564		bprm->unsafe |= LSM_UNSAFE_PTRACE;
1565
1566	/*
1567	 * This isn't strictly necessary, but it makes it harder for LSMs to
1568	 * mess up.
1569	 */
1570	if (task_no_new_privs(current))
1571		bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS;
1572
1573	/*
1574	 * If another task is sharing our fs, we cannot safely
1575	 * suid exec because the differently privileged task
1576	 * will be able to manipulate the current directory, etc.
1577	 * It would be nice to force an unshare instead...
1578	 */
1579	t = p;
1580	n_fs = 1;
1581	spin_lock(&p->fs->lock);
1582	rcu_read_lock();
1583	while_each_thread(p, t) {
1584		if (t->fs == p->fs)
1585			n_fs++;
1586	}
1587	rcu_read_unlock();
1588
1589	if (p->fs->users > n_fs)
1590		bprm->unsafe |= LSM_UNSAFE_SHARE;
1591	else
1592		p->fs->in_exec = 1;
 
 
 
 
 
1593	spin_unlock(&p->fs->lock);
 
 
1594}
1595
1596static void bprm_fill_uid(struct linux_binprm *bprm, struct file *file)
 
 
 
 
 
 
1597{
1598	/* Handle suid and sgid on files */
1599	struct user_namespace *mnt_userns;
1600	struct inode *inode = file_inode(file);
1601	unsigned int mode;
1602	vfsuid_t vfsuid;
1603	vfsgid_t vfsgid;
1604
1605	if (!mnt_may_suid(file->f_path.mnt))
1606		return;
1607
1608	if (task_no_new_privs(current))
1609		return;
1610
1611	mode = READ_ONCE(inode->i_mode);
1612	if (!(mode & (S_ISUID|S_ISGID)))
1613		return;
1614
1615	mnt_userns = file_mnt_user_ns(file);
1616
1617	/* Be careful if suid/sgid is set */
1618	inode_lock(inode);
1619
1620	/* reload atomically mode/uid/gid now that lock held */
1621	mode = inode->i_mode;
1622	vfsuid = i_uid_into_vfsuid(mnt_userns, inode);
1623	vfsgid = i_gid_into_vfsgid(mnt_userns, inode);
1624	inode_unlock(inode);
1625
1626	/* We ignore suid/sgid if there are no mappings for them in the ns */
1627	if (!vfsuid_has_mapping(bprm->cred->user_ns, vfsuid) ||
1628	    !vfsgid_has_mapping(bprm->cred->user_ns, vfsgid))
1629		return;
1630
1631	if (mode & S_ISUID) {
1632		bprm->per_clear |= PER_CLEAR_ON_SETID;
1633		bprm->cred->euid = vfsuid_into_kuid(vfsuid);
1634	}
 
 
 
 
 
 
1635
1636	if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1637		bprm->per_clear |= PER_CLEAR_ON_SETID;
1638		bprm->cred->egid = vfsgid_into_kgid(vfsgid);
 
 
 
 
 
 
 
1639	}
1640}
1641
1642/*
1643 * Compute brpm->cred based upon the final binary.
1644 */
1645static int bprm_creds_from_file(struct linux_binprm *bprm)
1646{
1647	/* Compute creds based on which file? */
1648	struct file *file = bprm->execfd_creds ? bprm->executable : bprm->file;
1649
1650	bprm_fill_uid(bprm, file);
1651	return security_bprm_creds_from_file(bprm, file);
1652}
1653
1654/*
1655 * Fill the binprm structure from the inode.
1656 * Read the first BINPRM_BUF_SIZE bytes
1657 *
1658 * This may be called multiple times for binary chains (scripts for example).
1659 */
1660static int prepare_binprm(struct linux_binprm *bprm)
1661{
1662	loff_t pos = 0;
1663
1664	memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1665	return kernel_read(bprm->file, bprm->buf, BINPRM_BUF_SIZE, &pos);
1666}
1667
 
 
1668/*
1669 * Arguments are '\0' separated strings found at the location bprm->p
1670 * points to; chop off the first by relocating brpm->p to right after
1671 * the first '\0' encountered.
1672 */
1673int remove_arg_zero(struct linux_binprm *bprm)
1674{
1675	int ret = 0;
1676	unsigned long offset;
1677	char *kaddr;
1678	struct page *page;
1679
1680	if (!bprm->argc)
1681		return 0;
1682
1683	do {
1684		offset = bprm->p & ~PAGE_MASK;
1685		page = get_arg_page(bprm, bprm->p, 0);
1686		if (!page) {
1687			ret = -EFAULT;
1688			goto out;
1689		}
1690		kaddr = kmap_local_page(page);
1691
1692		for (; offset < PAGE_SIZE && kaddr[offset];
1693				offset++, bprm->p++)
1694			;
1695
1696		kunmap_local(kaddr);
1697		put_arg_page(page);
 
 
 
1698	} while (offset == PAGE_SIZE);
1699
1700	bprm->p++;
1701	bprm->argc--;
1702	ret = 0;
1703
1704out:
1705	return ret;
1706}
1707EXPORT_SYMBOL(remove_arg_zero);
1708
1709#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1710/*
1711 * cycle the list of binary formats handler, until one recognizes the image
1712 */
1713static int search_binary_handler(struct linux_binprm *bprm)
1714{
1715	bool need_retry = IS_ENABLED(CONFIG_MODULES);
 
1716	struct linux_binfmt *fmt;
1717	int retval;
1718
1719	retval = prepare_binprm(bprm);
1720	if (retval < 0)
1721		return retval;
1722
1723	retval = security_bprm_check(bprm);
1724	if (retval)
1725		return retval;
1726
1727	retval = -ENOENT;
1728 retry:
1729	read_lock(&binfmt_lock);
1730	list_for_each_entry(fmt, &formats, lh) {
1731		if (!try_module_get(fmt->module))
1732			continue;
1733		read_unlock(&binfmt_lock);
1734
1735		retval = fmt->load_binary(bprm);
 
 
 
1736
 
 
1737		read_lock(&binfmt_lock);
1738		put_binfmt(fmt);
1739		if (bprm->point_of_no_return || (retval != -ENOEXEC)) {
 
 
 
 
1740			read_unlock(&binfmt_lock);
1741			return retval;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1742		}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1743	}
1744	read_unlock(&binfmt_lock);
1745
1746	if (need_retry) {
1747		if (printable(bprm->buf[0]) && printable(bprm->buf[1]) &&
1748		    printable(bprm->buf[2]) && printable(bprm->buf[3]))
1749			return retval;
1750		if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0)
1751			return retval;
1752		need_retry = false;
1753		goto retry;
1754	}
1755
1756	return retval;
1757}
1758
1759/* binfmt handlers will call back into begin_new_exec() on success. */
1760static int exec_binprm(struct linux_binprm *bprm)
1761{
1762	pid_t old_pid, old_vpid;
1763	int ret, depth;
1764
1765	/* Need to fetch pid before load_binary changes it */
1766	old_pid = current->pid;
1767	rcu_read_lock();
1768	old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1769	rcu_read_unlock();
1770
1771	/* This allows 4 levels of binfmt rewrites before failing hard. */
1772	for (depth = 0;; depth++) {
1773		struct file *exec;
1774		if (depth > 5)
1775			return -ELOOP;
1776
1777		ret = search_binary_handler(bprm);
1778		if (ret < 0)
1779			return ret;
1780		if (!bprm->interpreter)
1781			break;
1782
1783		exec = bprm->file;
1784		bprm->file = bprm->interpreter;
1785		bprm->interpreter = NULL;
1786
1787		allow_write_access(exec);
1788		if (unlikely(bprm->have_execfd)) {
1789			if (bprm->executable) {
1790				fput(exec);
1791				return -ENOEXEC;
1792			}
1793			bprm->executable = exec;
1794		} else
1795			fput(exec);
1796	}
1797
1798	audit_bprm(bprm);
1799	trace_sched_process_exec(current, old_pid, bprm);
1800	ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
1801	proc_exec_connector(current);
1802	return 0;
1803}
1804
1805/*
1806 * sys_execve() executes a new program.
1807 */
1808static int bprm_execve(struct linux_binprm *bprm,
1809		       int fd, struct filename *filename, int flags)
1810{
1811	struct file *file;
1812	int retval;
1813
1814	retval = prepare_bprm_creds(bprm);
1815	if (retval)
1816		return retval;
1817
1818	/*
1819	 * Check for unsafe execution states before exec_binprm(), which
1820	 * will call back into begin_new_exec(), into bprm_creds_from_file(),
1821	 * where setuid-ness is evaluated.
1822	 */
1823	check_unsafe_exec(bprm);
1824	current->in_execve = 1;
1825
1826	file = do_open_execat(fd, filename, flags);
1827	retval = PTR_ERR(file);
1828	if (IS_ERR(file))
1829		goto out_unmark;
1830
1831	sched_exec();
1832
1833	bprm->file = file;
1834	/*
1835	 * Record that a name derived from an O_CLOEXEC fd will be
1836	 * inaccessible after exec.  This allows the code in exec to
1837	 * choose to fail when the executable is not mmaped into the
1838	 * interpreter and an open file descriptor is not passed to
1839	 * the interpreter.  This makes for a better user experience
1840	 * than having the interpreter start and then immediately fail
1841	 * when it finds the executable is inaccessible.
1842	 */
1843	if (bprm->fdpath && get_close_on_exec(fd))
1844		bprm->interp_flags |= BINPRM_FLAGS_PATH_INACCESSIBLE;
1845
1846	/* Set the unchanging part of bprm->cred */
1847	retval = security_bprm_creds_for_exec(bprm);
1848	if (retval)
1849		goto out;
1850
1851	retval = exec_binprm(bprm);
1852	if (retval < 0)
1853		goto out;
1854
1855	/* execve succeeded */
1856	current->fs->in_exec = 0;
1857	current->in_execve = 0;
1858	rseq_execve(current);
1859	acct_update_integrals(current);
1860	task_numa_free(current, false);
1861	return retval;
1862
1863out:
1864	/*
1865	 * If past the point of no return ensure the code never
1866	 * returns to the userspace process.  Use an existing fatal
1867	 * signal if present otherwise terminate the process with
1868	 * SIGSEGV.
1869	 */
1870	if (bprm->point_of_no_return && !fatal_signal_pending(current))
1871		force_fatal_sig(SIGSEGV);
1872
1873out_unmark:
1874	current->fs->in_exec = 0;
1875	current->in_execve = 0;
1876
1877	return retval;
1878}
1879
1880static int do_execveat_common(int fd, struct filename *filename,
1881			      struct user_arg_ptr argv,
1882			      struct user_arg_ptr envp,
1883			      int flags)
1884{
1885	struct linux_binprm *bprm;
 
 
 
1886	int retval;
1887
1888	if (IS_ERR(filename))
1889		return PTR_ERR(filename);
1890
1891	/*
1892	 * We move the actual failure in case of RLIMIT_NPROC excess from
1893	 * set*uid() to execve() because too many poorly written programs
1894	 * don't check setuid() return code.  Here we additionally recheck
1895	 * whether NPROC limit is still exceeded.
1896	 */
1897	if ((current->flags & PF_NPROC_EXCEEDED) &&
1898	    is_rlimit_overlimit(current_ucounts(), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) {
1899		retval = -EAGAIN;
1900		goto out_ret;
1901	}
1902
1903	/* We're below the limit (still or again), so we don't want to make
1904	 * further execve() calls fail. */
1905	current->flags &= ~PF_NPROC_EXCEEDED;
1906
1907	bprm = alloc_bprm(fd, filename);
1908	if (IS_ERR(bprm)) {
1909		retval = PTR_ERR(bprm);
1910		goto out_ret;
1911	}
1912
1913	retval = count(argv, MAX_ARG_STRINGS);
1914	if (retval == 0)
1915		pr_warn_once("process '%s' launched '%s' with NULL argv: empty string added\n",
1916			     current->comm, bprm->filename);
1917	if (retval < 0)
1918		goto out_free;
1919	bprm->argc = retval;
1920
1921	retval = count(envp, MAX_ARG_STRINGS);
1922	if (retval < 0)
1923		goto out_free;
1924	bprm->envc = retval;
1925
1926	retval = bprm_stack_limits(bprm);
1927	if (retval < 0)
1928		goto out_free;
1929
1930	retval = copy_string_kernel(bprm->filename, bprm);
1931	if (retval < 0)
1932		goto out_free;
1933	bprm->exec = bprm->p;
1934
1935	retval = copy_strings(bprm->envc, envp, bprm);
1936	if (retval < 0)
1937		goto out_free;
1938
1939	retval = copy_strings(bprm->argc, argv, bprm);
1940	if (retval < 0)
1941		goto out_free;
 
 
1942
1943	/*
1944	 * When argv is empty, add an empty string ("") as argv[0] to
1945	 * ensure confused userspace programs that start processing
1946	 * from argv[1] won't end up walking envp. See also
1947	 * bprm_stack_limits().
1948	 */
1949	if (bprm->argc == 0) {
1950		retval = copy_string_kernel("", bprm);
1951		if (retval < 0)
1952			goto out_free;
1953		bprm->argc = 1;
1954	}
1955
1956	retval = bprm_execve(bprm, fd, filename, flags);
1957out_free:
1958	free_bprm(bprm);
1959
1960out_ret:
1961	putname(filename);
1962	return retval;
1963}
1964
1965int kernel_execve(const char *kernel_filename,
1966		  const char *const *argv, const char *const *envp)
1967{
1968	struct filename *filename;
1969	struct linux_binprm *bprm;
1970	int fd = AT_FDCWD;
1971	int retval;
1972
1973	/* It is non-sense for kernel threads to call execve */
1974	if (WARN_ON_ONCE(current->flags & PF_KTHREAD))
1975		return -EINVAL;
1976
1977	filename = getname_kernel(kernel_filename);
1978	if (IS_ERR(filename))
1979		return PTR_ERR(filename);
1980
1981	bprm = alloc_bprm(fd, filename);
1982	if (IS_ERR(bprm)) {
1983		retval = PTR_ERR(bprm);
1984		goto out_ret;
1985	}
1986
1987	retval = count_strings_kernel(argv);
1988	if (WARN_ON_ONCE(retval == 0))
1989		retval = -EINVAL;
1990	if (retval < 0)
1991		goto out_free;
1992	bprm->argc = retval;
1993
1994	retval = count_strings_kernel(envp);
1995	if (retval < 0)
1996		goto out_free;
1997	bprm->envc = retval;
1998
1999	retval = bprm_stack_limits(bprm);
 
2000	if (retval < 0)
2001		goto out_free;
2002
2003	retval = copy_string_kernel(bprm->filename, bprm);
2004	if (retval < 0)
2005		goto out_free;
2006	bprm->exec = bprm->p;
2007
2008	retval = copy_strings_kernel(bprm->envc, envp, bprm);
2009	if (retval < 0)
2010		goto out_free;
2011
2012	retval = copy_strings_kernel(bprm->argc, argv, bprm);
2013	if (retval < 0)
2014		goto out_free;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2015
2016	retval = bprm_execve(bprm, fd, filename, 0);
2017out_free:
2018	free_bprm(bprm);
 
 
 
 
2019out_ret:
2020	putname(filename);
2021	return retval;
2022}
2023
2024static int do_execve(struct filename *filename,
2025	const char __user *const __user *__argv,
2026	const char __user *const __user *__envp)
 
2027{
2028	struct user_arg_ptr argv = { .ptr.native = __argv };
2029	struct user_arg_ptr envp = { .ptr.native = __envp };
2030	return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
2031}
2032
2033static int do_execveat(int fd, struct filename *filename,
2034		const char __user *const __user *__argv,
2035		const char __user *const __user *__envp,
2036		int flags)
2037{
2038	struct user_arg_ptr argv = { .ptr.native = __argv };
2039	struct user_arg_ptr envp = { .ptr.native = __envp };
2040
2041	return do_execveat_common(fd, filename, argv, envp, flags);
2042}
2043
2044#ifdef CONFIG_COMPAT
2045static int compat_do_execve(struct filename *filename,
2046	const compat_uptr_t __user *__argv,
2047	const compat_uptr_t __user *__envp)
 
2048{
2049	struct user_arg_ptr argv = {
2050		.is_compat = true,
2051		.ptr.compat = __argv,
2052	};
2053	struct user_arg_ptr envp = {
2054		.is_compat = true,
2055		.ptr.compat = __envp,
2056	};
2057	return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
2058}
2059
2060static int compat_do_execveat(int fd, struct filename *filename,
2061			      const compat_uptr_t __user *__argv,
2062			      const compat_uptr_t __user *__envp,
2063			      int flags)
2064{
2065	struct user_arg_ptr argv = {
2066		.is_compat = true,
2067		.ptr.compat = __argv,
2068	};
2069	struct user_arg_ptr envp = {
2070		.is_compat = true,
2071		.ptr.compat = __envp,
2072	};
2073	return do_execveat_common(fd, filename, argv, envp, flags);
2074}
2075#endif
2076
2077void set_binfmt(struct linux_binfmt *new)
2078{
2079	struct mm_struct *mm = current->mm;
2080
2081	if (mm->binfmt)
2082		module_put(mm->binfmt->module);
2083
2084	mm->binfmt = new;
2085	if (new)
2086		__module_get(new->module);
2087}
 
2088EXPORT_SYMBOL(set_binfmt);
2089
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2090/*
2091 * set_dumpable stores three-value SUID_DUMP_* into mm->flags.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2092 */
2093void set_dumpable(struct mm_struct *mm, int value)
2094{
2095	if (WARN_ON((unsigned)value > SUID_DUMP_ROOT))
2096		return;
2097
2098	set_mask_bits(&mm->flags, MMF_DUMPABLE_MASK, value);
 
 
 
 
 
 
 
 
 
 
 
 
 
2099}
2100
2101SYSCALL_DEFINE3(execve,
2102		const char __user *, filename,
2103		const char __user *const __user *, argv,
2104		const char __user *const __user *, envp)
2105{
2106	return do_execve(getname(filename), argv, envp);
 
 
 
2107}
2108
2109SYSCALL_DEFINE5(execveat,
2110		int, fd, const char __user *, filename,
2111		const char __user *const __user *, argv,
2112		const char __user *const __user *, envp,
2113		int, flags)
2114{
2115	return do_execveat(fd,
2116			   getname_uflags(filename, flags),
2117			   argv, envp, flags);
2118}
2119
2120#ifdef CONFIG_COMPAT
2121COMPAT_SYSCALL_DEFINE3(execve, const char __user *, filename,
2122	const compat_uptr_t __user *, argv,
2123	const compat_uptr_t __user *, envp)
2124{
2125	return compat_do_execve(getname(filename), argv, envp);
2126}
2127
2128COMPAT_SYSCALL_DEFINE5(execveat, int, fd,
2129		       const char __user *, filename,
2130		       const compat_uptr_t __user *, argv,
2131		       const compat_uptr_t __user *, envp,
2132		       int,  flags)
2133{
2134	return compat_do_execveat(fd,
2135				  getname_uflags(filename, flags),
2136				  argv, envp, flags);
 
 
 
2137}
2138#endif
2139
2140#ifdef CONFIG_SYSCTL
2141
2142static int proc_dointvec_minmax_coredump(struct ctl_table *table, int write,
2143		void *buffer, size_t *lenp, loff_t *ppos)
 
 
 
 
 
 
 
 
 
 
2144{
2145	int error = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
 
 
 
2146
2147	if (!error)
2148		validate_coredump_safety();
2149	return error;
2150}
2151
2152static struct ctl_table fs_exec_sysctls[] = {
2153	{
2154		.procname	= "suid_dumpable",
2155		.data		= &suid_dumpable,
2156		.maxlen		= sizeof(int),
2157		.mode		= 0644,
2158		.proc_handler	= proc_dointvec_minmax_coredump,
2159		.extra1		= SYSCTL_ZERO,
2160		.extra2		= SYSCTL_TWO,
2161	},
2162	{ }
2163};
 
 
 
 
 
2164
2165static int __init init_fs_exec_sysctls(void)
2166{
2167	register_sysctl_init("fs", fs_exec_sysctls);
2168	return 0;
2169}
2170
2171fs_initcall(init_fs_exec_sysctls);
2172#endif /* CONFIG_SYSCTL */