linux/fs/exec.c
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   1/*
   2 *  linux/fs/exec.c
   3 *
   4 *  Copyright (C) 1991, 1992  Linus Torvalds
   5 */
   6
   7/*
   8 * #!-checking implemented by tytso.
   9 */
  10/*
  11 * Demand-loading implemented 01.12.91 - no need to read anything but
  12 * the header into memory. The inode of the executable is put into
  13 * "current->executable", and page faults do the actual loading. Clean.
  14 *
  15 * Once more I can proudly say that linux stood up to being changed: it
  16 * was less than 2 hours work to get demand-loading completely implemented.
  17 *
  18 * Demand loading changed July 1993 by Eric Youngdale.   Use mmap instead,
  19 * current->executable is only used by the procfs.  This allows a dispatch
  20 * table to check for several different types  of binary formats.  We keep
  21 * trying until we recognize the file or we run out of supported binary
  22 * formats. 
  23 */
  24
  25#include <linux/slab.h>
  26#include <linux/file.h>
  27#include <linux/fdtable.h>
  28#include <linux/mm.h>
  29#include <linux/vmacache.h>
  30#include <linux/stat.h>
  31#include <linux/fcntl.h>
  32#include <linux/swap.h>
  33#include <linux/string.h>
  34#include <linux/init.h>
  35#include <linux/pagemap.h>
  36#include <linux/perf_event.h>
  37#include <linux/highmem.h>
  38#include <linux/spinlock.h>
  39#include <linux/key.h>
  40#include <linux/personality.h>
  41#include <linux/binfmts.h>
  42#include <linux/utsname.h>
  43#include <linux/pid_namespace.h>
  44#include <linux/module.h>
  45#include <linux/namei.h>
  46#include <linux/mount.h>
  47#include <linux/security.h>
  48#include <linux/syscalls.h>
  49#include <linux/tsacct_kern.h>
  50#include <linux/cn_proc.h>
  51#include <linux/audit.h>
  52#include <linux/tracehook.h>
  53#include <linux/kmod.h>
  54#include <linux/fsnotify.h>
  55#include <linux/fs_struct.h>
  56#include <linux/pipe_fs_i.h>
  57#include <linux/oom.h>
  58#include <linux/compat.h>
  59
  60#include <asm/uaccess.h>
  61#include <asm/mmu_context.h>
  62#include <asm/tlb.h>
  63
  64#include <trace/events/task.h>
  65#include "internal.h"
  66
  67#include <trace/events/sched.h>
  68
  69int suid_dumpable = 0;
  70
  71static LIST_HEAD(formats);
  72static DEFINE_RWLOCK(binfmt_lock);
  73
  74void __register_binfmt(struct linux_binfmt * fmt, int insert)
  75{
  76        BUG_ON(!fmt);
  77        if (WARN_ON(!fmt->load_binary))
  78                return;
  79        write_lock(&binfmt_lock);
  80        insert ? list_add(&fmt->lh, &formats) :
  81                 list_add_tail(&fmt->lh, &formats);
  82        write_unlock(&binfmt_lock);
  83}
  84
  85EXPORT_SYMBOL(__register_binfmt);
  86
  87void unregister_binfmt(struct linux_binfmt * fmt)
  88{
  89        write_lock(&binfmt_lock);
  90        list_del(&fmt->lh);
  91        write_unlock(&binfmt_lock);
  92}
  93
  94EXPORT_SYMBOL(unregister_binfmt);
  95
  96static inline void put_binfmt(struct linux_binfmt * fmt)
  97{
  98        module_put(fmt->module);
  99}
 100
 101#ifdef CONFIG_USELIB
 102/*
 103 * Note that a shared library must be both readable and executable due to
 104 * security reasons.
 105 *
 106 * Also note that we take the address to load from from the file itself.
 107 */
 108SYSCALL_DEFINE1(uselib, const char __user *, library)
 109{
 110        struct linux_binfmt *fmt;
 111        struct file *file;
 112        struct filename *tmp = getname(library);
 113        int error = PTR_ERR(tmp);
 114        static const struct open_flags uselib_flags = {
 115                .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
 116                .acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN,
 117                .intent = LOOKUP_OPEN,
 118                .lookup_flags = LOOKUP_FOLLOW,
 119        };
 120
 121        if (IS_ERR(tmp))
 122                goto out;
 123
 124        file = do_filp_open(AT_FDCWD, tmp, &uselib_flags);
 125        putname(tmp);
 126        error = PTR_ERR(file);
 127        if (IS_ERR(file))
 128                goto out;
 129
 130        error = -EINVAL;
 131        if (!S_ISREG(file_inode(file)->i_mode))
 132                goto exit;
 133
 134        error = -EACCES;
 135        if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
 136                goto exit;
 137
 138        fsnotify_open(file);
 139
 140        error = -ENOEXEC;
 141
 142        read_lock(&binfmt_lock);
 143        list_for_each_entry(fmt, &formats, lh) {
 144                if (!fmt->load_shlib)
 145                        continue;
 146                if (!try_module_get(fmt->module))
 147                        continue;
 148                read_unlock(&binfmt_lock);
 149                error = fmt->load_shlib(file);
 150                read_lock(&binfmt_lock);
 151                put_binfmt(fmt);
 152                if (error != -ENOEXEC)
 153                        break;
 154        }
 155        read_unlock(&binfmt_lock);
 156exit:
 157        fput(file);
 158out:
 159        return error;
 160}
 161#endif /* #ifdef CONFIG_USELIB */
 162
 163#ifdef CONFIG_MMU
 164/*
 165 * The nascent bprm->mm is not visible until exec_mmap() but it can
 166 * use a lot of memory, account these pages in current->mm temporary
 167 * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
 168 * change the counter back via acct_arg_size(0).
 169 */
 170static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 171{
 172        struct mm_struct *mm = current->mm;
 173        long diff = (long)(pages - bprm->vma_pages);
 174
 175        if (!mm || !diff)
 176                return;
 177
 178        bprm->vma_pages = pages;
 179        add_mm_counter(mm, MM_ANONPAGES, diff);
 180}
 181
 182static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 183                int write)
 184{
 185        struct page *page;
 186        int ret;
 187
 188#ifdef CONFIG_STACK_GROWSUP
 189        if (write) {
 190                ret = expand_downwards(bprm->vma, pos);
 191                if (ret < 0)
 192                        return NULL;
 193        }
 194#endif
 195        ret = get_user_pages(current, bprm->mm, pos,
 196                        1, write, 1, &page, NULL);
 197        if (ret <= 0)
 198                return NULL;
 199
 200        if (write) {
 201                unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
 202                struct rlimit *rlim;
 203
 204                acct_arg_size(bprm, size / PAGE_SIZE);
 205
 206                /*
 207                 * We've historically supported up to 32 pages (ARG_MAX)
 208                 * of argument strings even with small stacks
 209                 */
 210                if (size <= ARG_MAX)
 211                        return page;
 212
 213                /*
 214                 * Limit to 1/4-th the stack size for the argv+env strings.
 215                 * This ensures that:
 216                 *  - the remaining binfmt code will not run out of stack space,
 217                 *  - the program will have a reasonable amount of stack left
 218                 *    to work from.
 219                 */
 220                rlim = current->signal->rlim;
 221                if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
 222                        put_page(page);
 223                        return NULL;
 224                }
 225        }
 226
 227        return page;
 228}
 229
 230static void put_arg_page(struct page *page)
 231{
 232        put_page(page);
 233}
 234
 235static void free_arg_page(struct linux_binprm *bprm, int i)
 236{
 237}
 238
 239static void free_arg_pages(struct linux_binprm *bprm)
 240{
 241}
 242
 243static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 244                struct page *page)
 245{
 246        flush_cache_page(bprm->vma, pos, page_to_pfn(page));
 247}
 248
 249static int __bprm_mm_init(struct linux_binprm *bprm)
 250{
 251        int err;
 252        struct vm_area_struct *vma = NULL;
 253        struct mm_struct *mm = bprm->mm;
 254
 255        bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
 256        if (!vma)
 257                return -ENOMEM;
 258
 259        down_write(&mm->mmap_sem);
 260        vma->vm_mm = mm;
 261
 262        /*
 263         * Place the stack at the largest stack address the architecture
 264         * supports. Later, we'll move this to an appropriate place. We don't
 265         * use STACK_TOP because that can depend on attributes which aren't
 266         * configured yet.
 267         */
 268        BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
 269        vma->vm_end = STACK_TOP_MAX;
 270        vma->vm_start = vma->vm_end - PAGE_SIZE;
 271        vma->vm_flags = VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
 272        vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 273        INIT_LIST_HEAD(&vma->anon_vma_chain);
 274
 275        err = insert_vm_struct(mm, vma);
 276        if (err)
 277                goto err;
 278
 279        mm->stack_vm = mm->total_vm = 1;
 280        arch_bprm_mm_init(mm, vma);
 281        up_write(&mm->mmap_sem);
 282        bprm->p = vma->vm_end - sizeof(void *);
 283        return 0;
 284err:
 285        up_write(&mm->mmap_sem);
 286        bprm->vma = NULL;
 287        kmem_cache_free(vm_area_cachep, vma);
 288        return err;
 289}
 290
 291static bool valid_arg_len(struct linux_binprm *bprm, long len)
 292{
 293        return len <= MAX_ARG_STRLEN;
 294}
 295
 296#else
 297
 298static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 299{
 300}
 301
 302static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 303                int write)
 304{
 305        struct page *page;
 306
 307        page = bprm->page[pos / PAGE_SIZE];
 308        if (!page && write) {
 309                page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
 310                if (!page)
 311                        return NULL;
 312                bprm->page[pos / PAGE_SIZE] = page;
 313        }
 314
 315        return page;
 316}
 317
 318static void put_arg_page(struct page *page)
 319{
 320}
 321
 322static void free_arg_page(struct linux_binprm *bprm, int i)
 323{
 324        if (bprm->page[i]) {
 325                __free_page(bprm->page[i]);
 326                bprm->page[i] = NULL;
 327        }
 328}
 329
 330static void free_arg_pages(struct linux_binprm *bprm)
 331{
 332        int i;
 333
 334        for (i = 0; i < MAX_ARG_PAGES; i++)
 335                free_arg_page(bprm, i);
 336}
 337
 338static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 339                struct page *page)
 340{
 341}
 342
 343static int __bprm_mm_init(struct linux_binprm *bprm)
 344{
 345        bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
 346        return 0;
 347}
 348
 349static bool valid_arg_len(struct linux_binprm *bprm, long len)
 350{
 351        return len <= bprm->p;
 352}
 353
 354#endif /* CONFIG_MMU */
 355
 356/*
 357 * Create a new mm_struct and populate it with a temporary stack
 358 * vm_area_struct.  We don't have enough context at this point to set the stack
 359 * flags, permissions, and offset, so we use temporary values.  We'll update
 360 * them later in setup_arg_pages().
 361 */
 362static int bprm_mm_init(struct linux_binprm *bprm)
 363{
 364        int err;
 365        struct mm_struct *mm = NULL;
 366
 367        bprm->mm = mm = mm_alloc();
 368        err = -ENOMEM;
 369        if (!mm)
 370                goto err;
 371
 372        err = __bprm_mm_init(bprm);
 373        if (err)
 374                goto err;
 375
 376        return 0;
 377
 378err:
 379        if (mm) {
 380                bprm->mm = NULL;
 381                mmdrop(mm);
 382        }
 383
 384        return err;
 385}
 386
 387struct user_arg_ptr {
 388#ifdef CONFIG_COMPAT
 389        bool is_compat;
 390#endif
 391        union {
 392                const char __user *const __user *native;
 393#ifdef CONFIG_COMPAT
 394                const compat_uptr_t __user *compat;
 395#endif
 396        } ptr;
 397};
 398
 399static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
 400{
 401        const char __user *native;
 402
 403#ifdef CONFIG_COMPAT
 404        if (unlikely(argv.is_compat)) {
 405                compat_uptr_t compat;
 406
 407                if (get_user(compat, argv.ptr.compat + nr))
 408                        return ERR_PTR(-EFAULT);
 409
 410                return compat_ptr(compat);
 411        }
 412#endif
 413
 414        if (get_user(native, argv.ptr.native + nr))
 415                return ERR_PTR(-EFAULT);
 416
 417        return native;
 418}
 419
 420/*
 421 * count() counts the number of strings in array ARGV.
 422 */
 423static int count(struct user_arg_ptr argv, int max)
 424{
 425        int i = 0;
 426
 427        if (argv.ptr.native != NULL) {
 428                for (;;) {
 429                        const char __user *p = get_user_arg_ptr(argv, i);
 430
 431                        if (!p)
 432                                break;
 433
 434                        if (IS_ERR(p))
 435                                return -EFAULT;
 436
 437                        if (i >= max)
 438                                return -E2BIG;
 439                        ++i;
 440
 441                        if (fatal_signal_pending(current))
 442                                return -ERESTARTNOHAND;
 443                        cond_resched();
 444                }
 445        }
 446        return i;
 447}
 448
 449/*
 450 * 'copy_strings()' copies argument/environment strings from the old
 451 * processes's memory to the new process's stack.  The call to get_user_pages()
 452 * ensures the destination page is created and not swapped out.
 453 */
 454static int copy_strings(int argc, struct user_arg_ptr argv,
 455                        struct linux_binprm *bprm)
 456{
 457        struct page *kmapped_page = NULL;
 458        char *kaddr = NULL;
 459        unsigned long kpos = 0;
 460        int ret;
 461
 462        while (argc-- > 0) {
 463                const char __user *str;
 464                int len;
 465                unsigned long pos;
 466
 467                ret = -EFAULT;
 468                str = get_user_arg_ptr(argv, argc);
 469                if (IS_ERR(str))
 470                        goto out;
 471
 472                len = strnlen_user(str, MAX_ARG_STRLEN);
 473                if (!len)
 474                        goto out;
 475
 476                ret = -E2BIG;
 477                if (!valid_arg_len(bprm, len))
 478                        goto out;
 479
 480                /* We're going to work our way backwords. */
 481                pos = bprm->p;
 482                str += len;
 483                bprm->p -= len;
 484
 485                while (len > 0) {
 486                        int offset, bytes_to_copy;
 487
 488                        if (fatal_signal_pending(current)) {
 489                                ret = -ERESTARTNOHAND;
 490                                goto out;
 491                        }
 492                        cond_resched();
 493
 494                        offset = pos % PAGE_SIZE;
 495                        if (offset == 0)
 496                                offset = PAGE_SIZE;
 497
 498                        bytes_to_copy = offset;
 499                        if (bytes_to_copy > len)
 500                                bytes_to_copy = len;
 501
 502                        offset -= bytes_to_copy;
 503                        pos -= bytes_to_copy;
 504                        str -= bytes_to_copy;
 505                        len -= bytes_to_copy;
 506
 507                        if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
 508                                struct page *page;
 509
 510                                page = get_arg_page(bprm, pos, 1);
 511                                if (!page) {
 512                                        ret = -E2BIG;
 513                                        goto out;
 514                                }
 515
 516                                if (kmapped_page) {
 517                                        flush_kernel_dcache_page(kmapped_page);
 518                                        kunmap(kmapped_page);
 519                                        put_arg_page(kmapped_page);
 520                                }
 521                                kmapped_page = page;
 522                                kaddr = kmap(kmapped_page);
 523                                kpos = pos & PAGE_MASK;
 524                                flush_arg_page(bprm, kpos, kmapped_page);
 525                        }
 526                        if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
 527                                ret = -EFAULT;
 528                                goto out;
 529                        }
 530                }
 531        }
 532        ret = 0;
 533out:
 534        if (kmapped_page) {
 535                flush_kernel_dcache_page(kmapped_page);
 536                kunmap(kmapped_page);
 537                put_arg_page(kmapped_page);
 538        }
 539        return ret;
 540}
 541
 542/*
 543 * Like copy_strings, but get argv and its values from kernel memory.
 544 */
 545int copy_strings_kernel(int argc, const char *const *__argv,
 546                        struct linux_binprm *bprm)
 547{
 548        int r;
 549        mm_segment_t oldfs = get_fs();
 550        struct user_arg_ptr argv = {
 551                .ptr.native = (const char __user *const  __user *)__argv,
 552        };
 553
 554        set_fs(KERNEL_DS);
 555        r = copy_strings(argc, argv, bprm);
 556        set_fs(oldfs);
 557
 558        return r;
 559}
 560EXPORT_SYMBOL(copy_strings_kernel);
 561
 562#ifdef CONFIG_MMU
 563
 564/*
 565 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 566 * the binfmt code determines where the new stack should reside, we shift it to
 567 * its final location.  The process proceeds as follows:
 568 *
 569 * 1) Use shift to calculate the new vma endpoints.
 570 * 2) Extend vma to cover both the old and new ranges.  This ensures the
 571 *    arguments passed to subsequent functions are consistent.
 572 * 3) Move vma's page tables to the new range.
 573 * 4) Free up any cleared pgd range.
 574 * 5) Shrink the vma to cover only the new range.
 575 */
 576static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 577{
 578        struct mm_struct *mm = vma->vm_mm;
 579        unsigned long old_start = vma->vm_start;
 580        unsigned long old_end = vma->vm_end;
 581        unsigned long length = old_end - old_start;
 582        unsigned long new_start = old_start - shift;
 583        unsigned long new_end = old_end - shift;
 584        struct mmu_gather tlb;
 585
 586        BUG_ON(new_start > new_end);
 587
 588        /*
 589         * ensure there are no vmas between where we want to go
 590         * and where we are
 591         */
 592        if (vma != find_vma(mm, new_start))
 593                return -EFAULT;
 594
 595        /*
 596         * cover the whole range: [new_start, old_end)
 597         */
 598        if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
 599                return -ENOMEM;
 600
 601        /*
 602         * move the page tables downwards, on failure we rely on
 603         * process cleanup to remove whatever mess we made.
 604         */
 605        if (length != move_page_tables(vma, old_start,
 606                                       vma, new_start, length, false))
 607                return -ENOMEM;
 608
 609        lru_add_drain();
 610        tlb_gather_mmu(&tlb, mm, old_start, old_end);
 611        if (new_end > old_start) {
 612                /*
 613                 * when the old and new regions overlap clear from new_end.
 614                 */
 615                free_pgd_range(&tlb, new_end, old_end, new_end,
 616                        vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
 617        } else {
 618                /*
 619                 * otherwise, clean from old_start; this is done to not touch
 620                 * the address space in [new_end, old_start) some architectures
 621                 * have constraints on va-space that make this illegal (IA64) -
 622                 * for the others its just a little faster.
 623                 */
 624                free_pgd_range(&tlb, old_start, old_end, new_end,
 625                        vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
 626        }
 627        tlb_finish_mmu(&tlb, old_start, old_end);
 628
 629        /*
 630         * Shrink the vma to just the new range.  Always succeeds.
 631         */
 632        vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
 633
 634        return 0;
 635}
 636
 637/*
 638 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 639 * the stack is optionally relocated, and some extra space is added.
 640 */
 641int setup_arg_pages(struct linux_binprm *bprm,
 642                    unsigned long stack_top,
 643                    int executable_stack)
 644{
 645        unsigned long ret;
 646        unsigned long stack_shift;
 647        struct mm_struct *mm = current->mm;
 648        struct vm_area_struct *vma = bprm->vma;
 649        struct vm_area_struct *prev = NULL;
 650        unsigned long vm_flags;
 651        unsigned long stack_base;
 652        unsigned long stack_size;
 653        unsigned long stack_expand;
 654        unsigned long rlim_stack;
 655
 656#ifdef CONFIG_STACK_GROWSUP
 657        /* Limit stack size */
 658        stack_base = rlimit_max(RLIMIT_STACK);
 659        if (stack_base > STACK_SIZE_MAX)
 660                stack_base = STACK_SIZE_MAX;
 661
 662        /* Make sure we didn't let the argument array grow too large. */
 663        if (vma->vm_end - vma->vm_start > stack_base)
 664                return -ENOMEM;
 665
 666        stack_base = PAGE_ALIGN(stack_top - stack_base);
 667
 668        stack_shift = vma->vm_start - stack_base;
 669        mm->arg_start = bprm->p - stack_shift;
 670        bprm->p = vma->vm_end - stack_shift;
 671#else
 672        stack_top = arch_align_stack(stack_top);
 673        stack_top = PAGE_ALIGN(stack_top);
 674
 675        if (unlikely(stack_top < mmap_min_addr) ||
 676            unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
 677                return -ENOMEM;
 678
 679        stack_shift = vma->vm_end - stack_top;
 680
 681        bprm->p -= stack_shift;
 682        mm->arg_start = bprm->p;
 683#endif
 684
 685        if (bprm->loader)
 686                bprm->loader -= stack_shift;
 687        bprm->exec -= stack_shift;
 688
 689        down_write(&mm->mmap_sem);
 690        vm_flags = VM_STACK_FLAGS;
 691
 692        /*
 693         * Adjust stack execute permissions; explicitly enable for
 694         * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
 695         * (arch default) otherwise.
 696         */
 697        if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 698                vm_flags |= VM_EXEC;
 699        else if (executable_stack == EXSTACK_DISABLE_X)
 700                vm_flags &= ~VM_EXEC;
 701        vm_flags |= mm->def_flags;
 702        vm_flags |= VM_STACK_INCOMPLETE_SETUP;
 703
 704        ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
 705                        vm_flags);
 706        if (ret)
 707                goto out_unlock;
 708        BUG_ON(prev != vma);
 709
 710        /* Move stack pages down in memory. */
 711        if (stack_shift) {
 712                ret = shift_arg_pages(vma, stack_shift);
 713                if (ret)
 714                        goto out_unlock;
 715        }
 716
 717        /* mprotect_fixup is overkill to remove the temporary stack flags */
 718        vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
 719
 720        stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
 721        stack_size = vma->vm_end - vma->vm_start;
 722        /*
 723         * Align this down to a page boundary as expand_stack
 724         * will align it up.
 725         */
 726        rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK;
 727#ifdef CONFIG_STACK_GROWSUP
 728        if (stack_size + stack_expand > rlim_stack)
 729                stack_base = vma->vm_start + rlim_stack;
 730        else
 731                stack_base = vma->vm_end + stack_expand;
 732#else
 733        if (stack_size + stack_expand > rlim_stack)
 734                stack_base = vma->vm_end - rlim_stack;
 735        else
 736                stack_base = vma->vm_start - stack_expand;
 737#endif
 738        current->mm->start_stack = bprm->p;
 739        ret = expand_stack(vma, stack_base);
 740        if (ret)
 741                ret = -EFAULT;
 742
 743out_unlock:
 744        up_write(&mm->mmap_sem);
 745        return ret;
 746}
 747EXPORT_SYMBOL(setup_arg_pages);
 748
 749#endif /* CONFIG_MMU */
 750
 751static struct file *do_open_execat(int fd, struct filename *name, int flags)
 752{
 753        struct file *file;
 754        int err;
 755        struct open_flags open_exec_flags = {
 756                .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
 757                .acc_mode = MAY_EXEC | MAY_OPEN,
 758                .intent = LOOKUP_OPEN,
 759                .lookup_flags = LOOKUP_FOLLOW,
 760        };
 761
 762        if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
 763                return ERR_PTR(-EINVAL);
 764        if (flags & AT_SYMLINK_NOFOLLOW)
 765                open_exec_flags.lookup_flags &= ~LOOKUP_FOLLOW;
 766        if (flags & AT_EMPTY_PATH)
 767                open_exec_flags.lookup_flags |= LOOKUP_EMPTY;
 768
 769        file = do_filp_open(fd, name, &open_exec_flags);
 770        if (IS_ERR(file))
 771                goto out;
 772
 773        err = -EACCES;
 774        if (!S_ISREG(file_inode(file)->i_mode))
 775                goto exit;
 776
 777        if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
 778                goto exit;
 779
 780        err = deny_write_access(file);
 781        if (err)
 782                goto exit;
 783
 784        if (name->name[0] != '\0')
 785                fsnotify_open(file);
 786
 787out:
 788        return file;
 789
 790exit:
 791        fput(file);
 792        return ERR_PTR(err);
 793}
 794
 795struct file *open_exec(const char *name)
 796{
 797        struct filename tmp = { .name = name };
 798        return do_open_execat(AT_FDCWD, &tmp, 0);
 799}
 800EXPORT_SYMBOL(open_exec);
 801
 802int kernel_read(struct file *file, loff_t offset,
 803                char *addr, unsigned long count)
 804{
 805        mm_segment_t old_fs;
 806        loff_t pos = offset;
 807        int result;
 808
 809        old_fs = get_fs();
 810        set_fs(get_ds());
 811        /* The cast to a user pointer is valid due to the set_fs() */
 812        result = vfs_read(file, (void __user *)addr, count, &pos);
 813        set_fs(old_fs);
 814        return result;
 815}
 816
 817EXPORT_SYMBOL(kernel_read);
 818
 819ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)
 820{
 821        ssize_t res = vfs_read(file, (void __user *)addr, len, &pos);
 822        if (res > 0)
 823                flush_icache_range(addr, addr + len);
 824        return res;
 825}
 826EXPORT_SYMBOL(read_code);
 827
 828static int exec_mmap(struct mm_struct *mm)
 829{
 830        struct task_struct *tsk;
 831        struct mm_struct *old_mm, *active_mm;
 832
 833        /* Notify parent that we're no longer interested in the old VM */
 834        tsk = current;
 835        old_mm = current->mm;
 836        mm_release(tsk, old_mm);
 837
 838        if (old_mm) {
 839                sync_mm_rss(old_mm);
 840                /*
 841                 * Make sure that if there is a core dump in progress
 842                 * for the old mm, we get out and die instead of going
 843                 * through with the exec.  We must hold mmap_sem around
 844                 * checking core_state and changing tsk->mm.
 845                 */
 846                down_read(&old_mm->mmap_sem);
 847                if (unlikely(old_mm->core_state)) {
 848                        up_read(&old_mm->mmap_sem);
 849                        return -EINTR;
 850                }
 851        }
 852        task_lock(tsk);
 853        active_mm = tsk->active_mm;
 854        tsk->mm = mm;
 855        tsk->active_mm = mm;
 856        activate_mm(active_mm, mm);
 857        tsk->mm->vmacache_seqnum = 0;
 858        vmacache_flush(tsk);
 859        task_unlock(tsk);
 860        if (old_mm) {
 861                up_read(&old_mm->mmap_sem);
 862                BUG_ON(active_mm != old_mm);
 863                setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm);
 864                mm_update_next_owner(old_mm);
 865                mmput(old_mm);
 866                return 0;
 867        }
 868        mmdrop(active_mm);
 869        return 0;
 870}
 871
 872/*
 873 * This function makes sure the current process has its own signal table,
 874 * so that flush_signal_handlers can later reset the handlers without
 875 * disturbing other processes.  (Other processes might share the signal
 876 * table via the CLONE_SIGHAND option to clone().)
 877 */
 878static int de_thread(struct task_struct *tsk)
 879{
 880        struct signal_struct *sig = tsk->signal;
 881        struct sighand_struct *oldsighand = tsk->sighand;
 882        spinlock_t *lock = &oldsighand->siglock;
 883
 884        if (thread_group_empty(tsk))
 885                goto no_thread_group;
 886
 887        /*
 888         * Kill all other threads in the thread group.
 889         */
 890        spin_lock_irq(lock);
 891        if (signal_group_exit(sig)) {
 892                /*
 893                 * Another group action in progress, just
 894                 * return so that the signal is processed.
 895                 */
 896                spin_unlock_irq(lock);
 897                return -EAGAIN;
 898        }
 899
 900        sig->group_exit_task = tsk;
 901        sig->notify_count = zap_other_threads(tsk);
 902        if (!thread_group_leader(tsk))
 903                sig->notify_count--;
 904
 905        while (sig->notify_count) {
 906                __set_current_state(TASK_KILLABLE);
 907                spin_unlock_irq(lock);
 908                schedule();
 909                if (unlikely(__fatal_signal_pending(tsk)))
 910                        goto killed;
 911                spin_lock_irq(lock);
 912        }
 913        spin_unlock_irq(lock);
 914
 915        /*
 916         * At this point all other threads have exited, all we have to
 917         * do is to wait for the thread group leader to become inactive,
 918         * and to assume its PID:
 919         */
 920        if (!thread_group_leader(tsk)) {
 921                struct task_struct *leader = tsk->group_leader;
 922
 923                sig->notify_count = -1; /* for exit_notify() */
 924                for (;;) {
 925                        threadgroup_change_begin(tsk);
 926                        write_lock_irq(&tasklist_lock);
 927                        if (likely(leader->exit_state))
 928                                break;
 929                        __set_current_state(TASK_KILLABLE);
 930                        write_unlock_irq(&tasklist_lock);
 931                        threadgroup_change_end(tsk);
 932                        schedule();
 933                        if (unlikely(__fatal_signal_pending(tsk)))
 934                                goto killed;
 935                }
 936
 937                /*
 938                 * The only record we have of the real-time age of a
 939                 * process, regardless of execs it's done, is start_time.
 940                 * All the past CPU time is accumulated in signal_struct
 941                 * from sister threads now dead.  But in this non-leader
 942                 * exec, nothing survives from the original leader thread,
 943                 * whose birth marks the true age of this process now.
 944                 * When we take on its identity by switching to its PID, we
 945                 * also take its birthdate (always earlier than our own).
 946                 */
 947                tsk->start_time = leader->start_time;
 948                tsk->real_start_time = leader->real_start_time;
 949
 950                BUG_ON(!same_thread_group(leader, tsk));
 951                BUG_ON(has_group_leader_pid(tsk));
 952                /*
 953                 * An exec() starts a new thread group with the
 954                 * TGID of the previous thread group. Rehash the
 955                 * two threads with a switched PID, and release
 956                 * the former thread group leader:
 957                 */
 958
 959                /* Become a process group leader with the old leader's pid.
 960                 * The old leader becomes a thread of the this thread group.
 961                 * Note: The old leader also uses this pid until release_task
 962                 *       is called.  Odd but simple and correct.
 963                 */
 964                tsk->pid = leader->pid;
 965                change_pid(tsk, PIDTYPE_PID, task_pid(leader));
 966                transfer_pid(leader, tsk, PIDTYPE_PGID);
 967                transfer_pid(leader, tsk, PIDTYPE_SID);
 968
 969                list_replace_rcu(&leader->tasks, &tsk->tasks);
 970                list_replace_init(&leader->sibling, &tsk->sibling);
 971
 972                tsk->group_leader = tsk;
 973                leader->group_leader = tsk;
 974
 975                tsk->exit_signal = SIGCHLD;
 976                leader->exit_signal = -1;
 977
 978                BUG_ON(leader->exit_state != EXIT_ZOMBIE);
 979                leader->exit_state = EXIT_DEAD;
 980
 981                /*
 982                 * We are going to release_task()->ptrace_unlink() silently,
 983                 * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
 984                 * the tracer wont't block again waiting for this thread.
 985                 */
 986                if (unlikely(leader->ptrace))
 987                        __wake_up_parent(leader, leader->parent);
 988                write_unlock_irq(&tasklist_lock);
 989                threadgroup_change_end(tsk);
 990
 991                release_task(leader);
 992        }
 993
 994        sig->group_exit_task = NULL;
 995        sig->notify_count = 0;
 996
 997no_thread_group:
 998        /* we have changed execution domain */
 999        tsk->exit_signal = SIGCHLD;
1000
1001        exit_itimers(sig);
1002        flush_itimer_signals();
1003
1004        if (atomic_read(&oldsighand->count) != 1) {
1005                struct sighand_struct *newsighand;
1006                /*
1007                 * This ->sighand is shared with the CLONE_SIGHAND
1008                 * but not CLONE_THREAD task, switch to the new one.
1009                 */
1010                newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1011                if (!newsighand)
1012                        return -ENOMEM;
1013
1014                atomic_set(&newsighand->count, 1);
1015                memcpy(newsighand->action, oldsighand->action,
1016                       sizeof(newsighand->action));
1017
1018                write_lock_irq(&tasklist_lock);
1019                spin_lock(&oldsighand->siglock);
1020                rcu_assign_pointer(tsk->sighand, newsighand);
1021                spin_unlock(&oldsighand->siglock);
1022                write_unlock_irq(&tasklist_lock);
1023
1024                __cleanup_sighand(oldsighand);
1025        }
1026
1027        BUG_ON(!thread_group_leader(tsk));
1028        return 0;
1029
1030killed:
1031        /* protects against exit_notify() and __exit_signal() */
1032        read_lock(&tasklist_lock);
1033        sig->group_exit_task = NULL;
1034        sig->notify_count = 0;
1035        read_unlock(&tasklist_lock);
1036        return -EAGAIN;
1037}
1038
1039char *get_task_comm(char *buf, struct task_struct *tsk)
1040{
1041        /* buf must be at least sizeof(tsk->comm) in size */
1042        task_lock(tsk);
1043        strncpy(buf, tsk->comm, sizeof(tsk->comm));
1044        task_unlock(tsk);
1045        return buf;
1046}
1047EXPORT_SYMBOL_GPL(get_task_comm);
1048
1049/*
1050 * These functions flushes out all traces of the currently running executable
1051 * so that a new one can be started
1052 */
1053
1054void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)
1055{
1056        task_lock(tsk);
1057        trace_task_rename(tsk, buf);
1058        strlcpy(tsk->comm, buf, sizeof(tsk->comm));
1059        task_unlock(tsk);
1060        perf_event_comm(tsk, exec);
1061}
1062
1063int flush_old_exec(struct linux_binprm * bprm)
1064{
1065        int retval;
1066
1067        /*
1068         * Make sure we have a private signal table and that
1069         * we are unassociated from the previous thread group.
1070         */
1071        retval = de_thread(current);
1072        if (retval)
1073                goto out;
1074
1075        set_mm_exe_file(bprm->mm, bprm->file);
1076        /*
1077         * Release all of the old mmap stuff
1078         */
1079        acct_arg_size(bprm, 0);
1080        retval = exec_mmap(bprm->mm);
1081        if (retval)
1082                goto out;
1083
1084        bprm->mm = NULL;                /* We're using it now */
1085
1086        set_fs(USER_DS);
1087        current->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD |
1088                                        PF_NOFREEZE | PF_NO_SETAFFINITY);
1089        flush_thread();
1090        current->personality &= ~bprm->per_clear;
1091
1092        return 0;
1093
1094out:
1095        return retval;
1096}
1097EXPORT_SYMBOL(flush_old_exec);
1098
1099void would_dump(struct linux_binprm *bprm, struct file *file)
1100{
1101        if (inode_permission(file_inode(file), MAY_READ) < 0)
1102                bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
1103}
1104EXPORT_SYMBOL(would_dump);
1105
1106void setup_new_exec(struct linux_binprm * bprm)
1107{
1108        arch_pick_mmap_layout(current->mm);
1109
1110        /* This is the point of no return */
1111        current->sas_ss_sp = current->sas_ss_size = 0;
1112
1113        if (uid_eq(current_euid(), current_uid()) && gid_eq(current_egid(), current_gid()))
1114                set_dumpable(current->mm, SUID_DUMP_USER);
1115        else
1116                set_dumpable(current->mm, suid_dumpable);
1117
1118        perf_event_exec();
1119        __set_task_comm(current, kbasename(bprm->filename), true);
1120
1121        /* Set the new mm task size. We have to do that late because it may
1122         * depend on TIF_32BIT which is only updated in flush_thread() on
1123         * some architectures like powerpc
1124         */
1125        current->mm->task_size = TASK_SIZE;
1126
1127        /* install the new credentials */
1128        if (!uid_eq(bprm->cred->uid, current_euid()) ||
1129            !gid_eq(bprm->cred->gid, current_egid())) {
1130                current->pdeath_signal = 0;
1131        } else {
1132                would_dump(bprm, bprm->file);
1133                if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)
1134                        set_dumpable(current->mm, suid_dumpable);
1135        }
1136
1137        /* An exec changes our domain. We are no longer part of the thread
1138           group */
1139        current->self_exec_id++;
1140        flush_signal_handlers(current, 0);
1141        do_close_on_exec(current->files);
1142}
1143EXPORT_SYMBOL(setup_new_exec);
1144
1145/*
1146 * Prepare credentials and lock ->cred_guard_mutex.
1147 * install_exec_creds() commits the new creds and drops the lock.
1148 * Or, if exec fails before, free_bprm() should release ->cred and
1149 * and unlock.
1150 */
1151int prepare_bprm_creds(struct linux_binprm *bprm)
1152{
1153        if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1154                return -ERESTARTNOINTR;
1155
1156        bprm->cred = prepare_exec_creds();
1157        if (likely(bprm->cred))
1158                return 0;
1159
1160        mutex_unlock(&current->signal->cred_guard_mutex);
1161        return -ENOMEM;
1162}
1163
1164static void free_bprm(struct linux_binprm *bprm)
1165{
1166        free_arg_pages(bprm);
1167        if (bprm->cred) {
1168                mutex_unlock(&current->signal->cred_guard_mutex);
1169                abort_creds(bprm->cred);
1170        }
1171        if (bprm->file) {
1172                allow_write_access(bprm->file);
1173                fput(bprm->file);
1174        }
1175        /* If a binfmt changed the interp, free it. */
1176        if (bprm->interp != bprm->filename)
1177                kfree(bprm->interp);
1178        kfree(bprm);
1179}
1180
1181int bprm_change_interp(char *interp, struct linux_binprm *bprm)
1182{
1183        /* If a binfmt changed the interp, free it first. */
1184        if (bprm->interp != bprm->filename)
1185                kfree(bprm->interp);
1186        bprm->interp = kstrdup(interp, GFP_KERNEL);
1187        if (!bprm->interp)
1188                return -ENOMEM;
1189        return 0;
1190}
1191EXPORT_SYMBOL(bprm_change_interp);
1192
1193/*
1194 * install the new credentials for this executable
1195 */
1196void install_exec_creds(struct linux_binprm *bprm)
1197{
1198        security_bprm_committing_creds(bprm);
1199
1200        commit_creds(bprm->cred);
1201        bprm->cred = NULL;
1202
1203        /*
1204         * Disable monitoring for regular users
1205         * when executing setuid binaries. Must
1206         * wait until new credentials are committed
1207         * by commit_creds() above
1208         */
1209        if (get_dumpable(current->mm) != SUID_DUMP_USER)
1210                perf_event_exit_task(current);
1211        /*
1212         * cred_guard_mutex must be held at least to this point to prevent
1213         * ptrace_attach() from altering our determination of the task's
1214         * credentials; any time after this it may be unlocked.
1215         */
1216        security_bprm_committed_creds(bprm);
1217        mutex_unlock(&current->signal->cred_guard_mutex);
1218}
1219EXPORT_SYMBOL(install_exec_creds);
1220
1221/*
1222 * determine how safe it is to execute the proposed program
1223 * - the caller must hold ->cred_guard_mutex to protect against
1224 *   PTRACE_ATTACH or seccomp thread-sync
1225 */
1226static void check_unsafe_exec(struct linux_binprm *bprm)
1227{
1228        struct task_struct *p = current, *t;
1229        unsigned n_fs;
1230
1231        if (p->ptrace) {
1232                if (p->ptrace & PT_PTRACE_CAP)
1233                        bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP;
1234                else
1235                        bprm->unsafe |= LSM_UNSAFE_PTRACE;
1236        }
1237
1238        /*
1239         * This isn't strictly necessary, but it makes it harder for LSMs to
1240         * mess up.
1241         */
1242        if (task_no_new_privs(current))
1243                bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS;
1244
1245        t = p;
1246        n_fs = 1;
1247        spin_lock(&p->fs->lock);
1248        rcu_read_lock();
1249        while_each_thread(p, t) {
1250                if (t->fs == p->fs)
1251                        n_fs++;
1252        }
1253        rcu_read_unlock();
1254
1255        if (p->fs->users > n_fs)
1256                bprm->unsafe |= LSM_UNSAFE_SHARE;
1257        else
1258                p->fs->in_exec = 1;
1259        spin_unlock(&p->fs->lock);
1260}
1261
1262/*
1263 * Fill the binprm structure from the inode.
1264 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1265 *
1266 * This may be called multiple times for binary chains (scripts for example).
1267 */
1268int prepare_binprm(struct linux_binprm *bprm)
1269{
1270        struct inode *inode = file_inode(bprm->file);
1271        umode_t mode = inode->i_mode;
1272        int retval;
1273
1274
1275        /* clear any previous set[ug]id data from a previous binary */
1276        bprm->cred->euid = current_euid();
1277        bprm->cred->egid = current_egid();
1278
1279        if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID) &&
1280            !task_no_new_privs(current) &&
1281            kuid_has_mapping(bprm->cred->user_ns, inode->i_uid) &&
1282            kgid_has_mapping(bprm->cred->user_ns, inode->i_gid)) {
1283                /* Set-uid? */
1284                if (mode & S_ISUID) {
1285                        bprm->per_clear |= PER_CLEAR_ON_SETID;
1286                        bprm->cred->euid = inode->i_uid;
1287                }
1288
1289                /* Set-gid? */
1290                /*
1291                 * If setgid is set but no group execute bit then this
1292                 * is a candidate for mandatory locking, not a setgid
1293                 * executable.
1294                 */
1295                if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1296                        bprm->per_clear |= PER_CLEAR_ON_SETID;
1297                        bprm->cred->egid = inode->i_gid;
1298                }
1299        }
1300
1301        /* fill in binprm security blob */
1302        retval = security_bprm_set_creds(bprm);
1303        if (retval)
1304                return retval;
1305        bprm->cred_prepared = 1;
1306
1307        memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1308        return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1309}
1310
1311EXPORT_SYMBOL(prepare_binprm);
1312
1313/*
1314 * Arguments are '\0' separated strings found at the location bprm->p
1315 * points to; chop off the first by relocating brpm->p to right after
1316 * the first '\0' encountered.
1317 */
1318int remove_arg_zero(struct linux_binprm *bprm)
1319{
1320        int ret = 0;
1321        unsigned long offset;
1322        char *kaddr;
1323        struct page *page;
1324
1325        if (!bprm->argc)
1326                return 0;
1327
1328        do {
1329                offset = bprm->p & ~PAGE_MASK;
1330                page = get_arg_page(bprm, bprm->p, 0);
1331                if (!page) {
1332                        ret = -EFAULT;
1333                        goto out;
1334                }
1335                kaddr = kmap_atomic(page);
1336
1337                for (; offset < PAGE_SIZE && kaddr[offset];
1338                                offset++, bprm->p++)
1339                        ;
1340
1341                kunmap_atomic(kaddr);
1342                put_arg_page(page);
1343
1344                if (offset == PAGE_SIZE)
1345                        free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1346        } while (offset == PAGE_SIZE);
1347
1348        bprm->p++;
1349        bprm->argc--;
1350        ret = 0;
1351
1352out:
1353        return ret;
1354}
1355EXPORT_SYMBOL(remove_arg_zero);
1356
1357#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1358/*
1359 * cycle the list of binary formats handler, until one recognizes the image
1360 */
1361int search_binary_handler(struct linux_binprm *bprm)
1362{
1363        bool need_retry = IS_ENABLED(CONFIG_MODULES);
1364        struct linux_binfmt *fmt;
1365        int retval;
1366
1367        /* This allows 4 levels of binfmt rewrites before failing hard. */
1368        if (bprm->recursion_depth > 5)
1369                return -ELOOP;
1370
1371        retval = security_bprm_check(bprm);
1372        if (retval)
1373                return retval;
1374
1375        retval = -ENOENT;
1376 retry:
1377        read_lock(&binfmt_lock);
1378        list_for_each_entry(fmt, &formats, lh) {
1379                if (!try_module_get(fmt->module))
1380                        continue;
1381                read_unlock(&binfmt_lock);
1382                bprm->recursion_depth++;
1383                retval = fmt->load_binary(bprm);
1384                read_lock(&binfmt_lock);
1385                put_binfmt(fmt);
1386                bprm->recursion_depth--;
1387                if (retval < 0 && !bprm->mm) {
1388                        /* we got to flush_old_exec() and failed after it */
1389                        read_unlock(&binfmt_lock);
1390                        force_sigsegv(SIGSEGV, current);
1391                        return retval;
1392                }
1393                if (retval != -ENOEXEC || !bprm->file) {
1394                        read_unlock(&binfmt_lock);
1395                        return retval;
1396                }
1397        }
1398        read_unlock(&binfmt_lock);
1399
1400        if (need_retry) {
1401                if (printable(bprm->buf[0]) && printable(bprm->buf[1]) &&
1402                    printable(bprm->buf[2]) && printable(bprm->buf[3]))
1403                        return retval;
1404                if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0)
1405                        return retval;
1406                need_retry = false;
1407                goto retry;
1408        }
1409
1410        return retval;
1411}
1412EXPORT_SYMBOL(search_binary_handler);
1413
1414static int exec_binprm(struct linux_binprm *bprm)
1415{
1416        pid_t old_pid, old_vpid;
1417        int ret;
1418
1419        /* Need to fetch pid before load_binary changes it */
1420        old_pid = current->pid;
1421        rcu_read_lock();
1422        old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1423        rcu_read_unlock();
1424
1425        ret = search_binary_handler(bprm);
1426        if (ret >= 0) {
1427                audit_bprm(bprm);
1428                trace_sched_process_exec(current, old_pid, bprm);
1429                ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
1430                proc_exec_connector(current);
1431        }
1432
1433        return ret;
1434}
1435
1436/*
1437 * sys_execve() executes a new program.
1438 */
1439static int do_execveat_common(int fd, struct filename *filename,
1440                              struct user_arg_ptr argv,
1441                              struct user_arg_ptr envp,
1442                              int flags)
1443{
1444        char *pathbuf = NULL;
1445        struct linux_binprm *bprm;
1446        struct file *file;
1447        struct files_struct *displaced;
1448        int retval;
1449
1450        if (IS_ERR(filename))
1451                return PTR_ERR(filename);
1452
1453        /*
1454         * We move the actual failure in case of RLIMIT_NPROC excess from
1455         * set*uid() to execve() because too many poorly written programs
1456         * don't check setuid() return code.  Here we additionally recheck
1457         * whether NPROC limit is still exceeded.
1458         */
1459        if ((current->flags & PF_NPROC_EXCEEDED) &&
1460            atomic_read(&current_user()->processes) > rlimit(RLIMIT_NPROC)) {
1461                retval = -EAGAIN;
1462                goto out_ret;
1463        }
1464
1465        /* We're below the limit (still or again), so we don't want to make
1466         * further execve() calls fail. */
1467        current->flags &= ~PF_NPROC_EXCEEDED;
1468
1469        retval = unshare_files(&displaced);
1470        if (retval)
1471                goto out_ret;
1472
1473        retval = -ENOMEM;
1474        bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1475        if (!bprm)
1476                goto out_files;
1477
1478        retval = prepare_bprm_creds(bprm);
1479        if (retval)
1480                goto out_free;
1481
1482        check_unsafe_exec(bprm);
1483        current->in_execve = 1;
1484
1485        file = do_open_execat(fd, filename, flags);
1486        retval = PTR_ERR(file);
1487        if (IS_ERR(file))
1488                goto out_unmark;
1489
1490        sched_exec();
1491
1492        bprm->file = file;
1493        if (fd == AT_FDCWD || filename->name[0] == '/') {
1494                bprm->filename = filename->name;
1495        } else {
1496                if (filename->name[0] == '\0')
1497                        pathbuf = kasprintf(GFP_TEMPORARY, "/dev/fd/%d", fd);
1498                else
1499                        pathbuf = kasprintf(GFP_TEMPORARY, "/dev/fd/%d/%s",
1500                                            fd, filename->name);
1501                if (!pathbuf) {
1502                        retval = -ENOMEM;
1503                        goto out_unmark;
1504                }
1505                /*
1506                 * Record that a name derived from an O_CLOEXEC fd will be
1507                 * inaccessible after exec. Relies on having exclusive access to
1508                 * current->files (due to unshare_files above).
1509                 */
1510                if (close_on_exec(fd, rcu_dereference_raw(current->files->fdt)))
1511                        bprm->interp_flags |= BINPRM_FLAGS_PATH_INACCESSIBLE;
1512                bprm->filename = pathbuf;
1513        }
1514        bprm->interp = bprm->filename;
1515
1516        retval = bprm_mm_init(bprm);
1517        if (retval)
1518                goto out_unmark;
1519
1520        bprm->argc = count(argv, MAX_ARG_STRINGS);
1521        if ((retval = bprm->argc) < 0)
1522                goto out;
1523
1524        bprm->envc = count(envp, MAX_ARG_STRINGS);
1525        if ((retval = bprm->envc) < 0)
1526                goto out;
1527
1528        retval = prepare_binprm(bprm);
1529        if (retval < 0)
1530                goto out;
1531
1532        retval = copy_strings_kernel(1, &bprm->filename, bprm);
1533        if (retval < 0)
1534                goto out;
1535
1536        bprm->exec = bprm->p;
1537        retval = copy_strings(bprm->envc, envp, bprm);
1538        if (retval < 0)
1539                goto out;
1540
1541        retval = copy_strings(bprm->argc, argv, bprm);
1542        if (retval < 0)
1543                goto out;
1544
1545        retval = exec_binprm(bprm);
1546        if (retval < 0)
1547                goto out;
1548
1549        /* execve succeeded */
1550        current->fs->in_exec = 0;
1551        current->in_execve = 0;
1552        acct_update_integrals(current);
1553        task_numa_free(current);
1554        free_bprm(bprm);
1555        kfree(pathbuf);
1556        putname(filename);
1557        if (displaced)
1558                put_files_struct(displaced);
1559        return retval;
1560
1561out:
1562        if (bprm->mm) {
1563                acct_arg_size(bprm, 0);
1564                mmput(bprm->mm);
1565        }
1566
1567out_unmark:
1568        current->fs->in_exec = 0;
1569        current->in_execve = 0;
1570
1571out_free:
1572        free_bprm(bprm);
1573        kfree(pathbuf);
1574
1575out_files:
1576        if (displaced)
1577                reset_files_struct(displaced);
1578out_ret:
1579        putname(filename);
1580        return retval;
1581}
1582
1583int do_execve(struct filename *filename,
1584        const char __user *const __user *__argv,
1585        const char __user *const __user *__envp)
1586{
1587        struct user_arg_ptr argv = { .ptr.native = __argv };
1588        struct user_arg_ptr envp = { .ptr.native = __envp };
1589        return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
1590}
1591
1592int do_execveat(int fd, struct filename *filename,
1593                const char __user *const __user *__argv,
1594                const char __user *const __user *__envp,
1595                int flags)
1596{
1597        struct user_arg_ptr argv = { .ptr.native = __argv };
1598        struct user_arg_ptr envp = { .ptr.native = __envp };
1599
1600        return do_execveat_common(fd, filename, argv, envp, flags);
1601}
1602
1603#ifdef CONFIG_COMPAT
1604static int compat_do_execve(struct filename *filename,
1605        const compat_uptr_t __user *__argv,
1606        const compat_uptr_t __user *__envp)
1607{
1608        struct user_arg_ptr argv = {
1609                .is_compat = true,
1610                .ptr.compat = __argv,
1611        };
1612        struct user_arg_ptr envp = {
1613                .is_compat = true,
1614                .ptr.compat = __envp,
1615        };
1616        return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
1617}
1618
1619static int compat_do_execveat(int fd, struct filename *filename,
1620                              const compat_uptr_t __user *__argv,
1621                              const compat_uptr_t __user *__envp,
1622                              int flags)
1623{
1624        struct user_arg_ptr argv = {
1625                .is_compat = true,
1626                .ptr.compat = __argv,
1627        };
1628        struct user_arg_ptr envp = {
1629                .is_compat = true,
1630                .ptr.compat = __envp,
1631        };
1632        return do_execveat_common(fd, filename, argv, envp, flags);
1633}
1634#endif
1635
1636void set_binfmt(struct linux_binfmt *new)
1637{
1638        struct mm_struct *mm = current->mm;
1639
1640        if (mm->binfmt)
1641                module_put(mm->binfmt->module);
1642
1643        mm->binfmt = new;
1644        if (new)
1645                __module_get(new->module);
1646}
1647EXPORT_SYMBOL(set_binfmt);
1648
1649/*
1650 * set_dumpable stores three-value SUID_DUMP_* into mm->flags.
1651 */
1652void set_dumpable(struct mm_struct *mm, int value)
1653{
1654        unsigned long old, new;
1655
1656        if (WARN_ON((unsigned)value > SUID_DUMP_ROOT))
1657                return;
1658
1659        do {
1660                old = ACCESS_ONCE(mm->flags);
1661                new = (old & ~MMF_DUMPABLE_MASK) | value;
1662        } while (cmpxchg(&mm->flags, old, new) != old);
1663}
1664
1665SYSCALL_DEFINE3(execve,
1666                const char __user *, filename,
1667                const char __user *const __user *, argv,
1668                const char __user *const __user *, envp)
1669{
1670        return do_execve(getname(filename), argv, envp);
1671}
1672
1673SYSCALL_DEFINE5(execveat,
1674                int, fd, const char __user *, filename,
1675                const char __user *const __user *, argv,
1676                const char __user *const __user *, envp,
1677                int, flags)
1678{
1679        int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
1680
1681        return do_execveat(fd,
1682                           getname_flags(filename, lookup_flags, NULL),
1683                           argv, envp, flags);
1684}
1685
1686#ifdef CONFIG_COMPAT
1687COMPAT_SYSCALL_DEFINE3(execve, const char __user *, filename,
1688        const compat_uptr_t __user *, argv,
1689        const compat_uptr_t __user *, envp)
1690{
1691        return compat_do_execve(getname(filename), argv, envp);
1692}
1693
1694COMPAT_SYSCALL_DEFINE5(execveat, int, fd,
1695                       const char __user *, filename,
1696                       const compat_uptr_t __user *, argv,
1697                       const compat_uptr_t __user *, envp,
1698                       int,  flags)
1699{
1700        int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
1701
1702        return compat_do_execveat(fd,
1703                                  getname_flags(filename, lookup_flags, NULL),
1704                                  argv, envp, flags);
1705}
1706#endif
1707
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