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