arm64: dts: rockchip: add power button for rk3399 excavator linux
[firefly-linux-kernel-4.4.55.git] / fs / exec.c
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
69 int suid_dumpable = 0;
70
71 static LIST_HEAD(formats);
72 static DEFINE_RWLOCK(binfmt_lock);
73
74 void __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
85 EXPORT_SYMBOL(__register_binfmt);
86
87 void unregister_binfmt(struct linux_binfmt * fmt)
88 {
89         write_lock(&binfmt_lock);
90         list_del(&fmt->lh);
91         write_unlock(&binfmt_lock);
92 }
93
94 EXPORT_SYMBOL(unregister_binfmt);
95
96 static inline void put_binfmt(struct linux_binfmt * fmt)
97 {
98         module_put(fmt->module);
99 }
100
101 bool path_noexec(const struct path *path)
102 {
103         return (path->mnt->mnt_flags & MNT_NOEXEC) ||
104                (path->mnt->mnt_sb->s_iflags & SB_I_NOEXEC);
105 }
106
107 #ifdef CONFIG_USELIB
108 /*
109  * Note that a shared library must be both readable and executable due to
110  * security reasons.
111  *
112  * Also note that we take the address to load from from the file itself.
113  */
114 SYSCALL_DEFINE1(uselib, const char __user *, library)
115 {
116         struct linux_binfmt *fmt;
117         struct file *file;
118         struct filename *tmp = getname(library);
119         int error = PTR_ERR(tmp);
120         static const struct open_flags uselib_flags = {
121                 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
122                 .acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN,
123                 .intent = LOOKUP_OPEN,
124                 .lookup_flags = LOOKUP_FOLLOW,
125         };
126
127         if (IS_ERR(tmp))
128                 goto out;
129
130         file = do_filp_open(AT_FDCWD, tmp, &uselib_flags);
131         putname(tmp);
132         error = PTR_ERR(file);
133         if (IS_ERR(file))
134                 goto out;
135
136         error = -EINVAL;
137         if (!S_ISREG(file_inode(file)->i_mode))
138                 goto exit;
139
140         error = -EACCES;
141         if (path_noexec(&file->f_path))
142                 goto exit;
143
144         fsnotify_open(file);
145
146         error = -ENOEXEC;
147
148         read_lock(&binfmt_lock);
149         list_for_each_entry(fmt, &formats, lh) {
150                 if (!fmt->load_shlib)
151                         continue;
152                 if (!try_module_get(fmt->module))
153                         continue;
154                 read_unlock(&binfmt_lock);
155                 error = fmt->load_shlib(file);
156                 read_lock(&binfmt_lock);
157                 put_binfmt(fmt);
158                 if (error != -ENOEXEC)
159                         break;
160         }
161         read_unlock(&binfmt_lock);
162 exit:
163         fput(file);
164 out:
165         return error;
166 }
167 #endif /* #ifdef CONFIG_USELIB */
168
169 #ifdef CONFIG_MMU
170 /*
171  * The nascent bprm->mm is not visible until exec_mmap() but it can
172  * use a lot of memory, account these pages in current->mm temporary
173  * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
174  * change the counter back via acct_arg_size(0).
175  */
176 static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
177 {
178         struct mm_struct *mm = current->mm;
179         long diff = (long)(pages - bprm->vma_pages);
180
181         if (!mm || !diff)
182                 return;
183
184         bprm->vma_pages = pages;
185         add_mm_counter(mm, MM_ANONPAGES, diff);
186 }
187
188 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
189                 int write)
190 {
191         struct page *page;
192         int ret;
193
194 #ifdef CONFIG_STACK_GROWSUP
195         if (write) {
196                 ret = expand_downwards(bprm->vma, pos);
197                 if (ret < 0)
198                         return NULL;
199         }
200 #endif
201         ret = get_user_pages(current, bprm->mm, pos,
202                         1, write, 1, &page, NULL);
203         if (ret <= 0)
204                 return NULL;
205
206         if (write) {
207                 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
208                 struct rlimit *rlim;
209
210                 acct_arg_size(bprm, size / PAGE_SIZE);
211
212                 /*
213                  * We've historically supported up to 32 pages (ARG_MAX)
214                  * of argument strings even with small stacks
215                  */
216                 if (size <= ARG_MAX)
217                         return page;
218
219                 /*
220                  * Limit to 1/4-th the stack size for the argv+env strings.
221                  * This ensures that:
222                  *  - the remaining binfmt code will not run out of stack space,
223                  *  - the program will have a reasonable amount of stack left
224                  *    to work from.
225                  */
226                 rlim = current->signal->rlim;
227                 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
228                         put_page(page);
229                         return NULL;
230                 }
231         }
232
233         return page;
234 }
235
236 static void put_arg_page(struct page *page)
237 {
238         put_page(page);
239 }
240
241 static void free_arg_page(struct linux_binprm *bprm, int i)
242 {
243 }
244
245 static void free_arg_pages(struct linux_binprm *bprm)
246 {
247 }
248
249 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
250                 struct page *page)
251 {
252         flush_cache_page(bprm->vma, pos, page_to_pfn(page));
253 }
254
255 static int __bprm_mm_init(struct linux_binprm *bprm)
256 {
257         int err;
258         struct vm_area_struct *vma = NULL;
259         struct mm_struct *mm = bprm->mm;
260
261         bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
262         if (!vma)
263                 return -ENOMEM;
264
265         down_write(&mm->mmap_sem);
266         vma->vm_mm = mm;
267
268         /*
269          * Place the stack at the largest stack address the architecture
270          * supports. Later, we'll move this to an appropriate place. We don't
271          * use STACK_TOP because that can depend on attributes which aren't
272          * configured yet.
273          */
274         BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
275         vma->vm_end = STACK_TOP_MAX;
276         vma->vm_start = vma->vm_end - PAGE_SIZE;
277         vma->vm_flags = VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
278         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
279         INIT_LIST_HEAD(&vma->anon_vma_chain);
280
281         err = insert_vm_struct(mm, vma);
282         if (err)
283                 goto err;
284
285         mm->stack_vm = mm->total_vm = 1;
286         arch_bprm_mm_init(mm, vma);
287         up_write(&mm->mmap_sem);
288         bprm->p = vma->vm_end - sizeof(void *);
289         return 0;
290 err:
291         up_write(&mm->mmap_sem);
292         bprm->vma = NULL;
293         kmem_cache_free(vm_area_cachep, vma);
294         return err;
295 }
296
297 static bool valid_arg_len(struct linux_binprm *bprm, long len)
298 {
299         return len <= MAX_ARG_STRLEN;
300 }
301
302 #else
303
304 static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
305 {
306 }
307
308 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
309                 int write)
310 {
311         struct page *page;
312
313         page = bprm->page[pos / PAGE_SIZE];
314         if (!page && write) {
315                 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
316                 if (!page)
317                         return NULL;
318                 bprm->page[pos / PAGE_SIZE] = page;
319         }
320
321         return page;
322 }
323
324 static void put_arg_page(struct page *page)
325 {
326 }
327
328 static void free_arg_page(struct linux_binprm *bprm, int i)
329 {
330         if (bprm->page[i]) {
331                 __free_page(bprm->page[i]);
332                 bprm->page[i] = NULL;
333         }
334 }
335
336 static void free_arg_pages(struct linux_binprm *bprm)
337 {
338         int i;
339
340         for (i = 0; i < MAX_ARG_PAGES; i++)
341                 free_arg_page(bprm, i);
342 }
343
344 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
345                 struct page *page)
346 {
347 }
348
349 static int __bprm_mm_init(struct linux_binprm *bprm)
350 {
351         bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
352         return 0;
353 }
354
355 static bool valid_arg_len(struct linux_binprm *bprm, long len)
356 {
357         return len <= bprm->p;
358 }
359
360 #endif /* CONFIG_MMU */
361
362 /*
363  * Create a new mm_struct and populate it with a temporary stack
364  * vm_area_struct.  We don't have enough context at this point to set the stack
365  * flags, permissions, and offset, so we use temporary values.  We'll update
366  * them later in setup_arg_pages().
367  */
368 static int bprm_mm_init(struct linux_binprm *bprm)
369 {
370         int err;
371         struct mm_struct *mm = NULL;
372
373         bprm->mm = mm = mm_alloc();
374         err = -ENOMEM;
375         if (!mm)
376                 goto err;
377
378         err = __bprm_mm_init(bprm);
379         if (err)
380                 goto err;
381
382         return 0;
383
384 err:
385         if (mm) {
386                 bprm->mm = NULL;
387                 mmdrop(mm);
388         }
389
390         return err;
391 }
392
393 struct user_arg_ptr {
394 #ifdef CONFIG_COMPAT
395         bool is_compat;
396 #endif
397         union {
398                 const char __user *const __user *native;
399 #ifdef CONFIG_COMPAT
400                 const compat_uptr_t __user *compat;
401 #endif
402         } ptr;
403 };
404
405 static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
406 {
407         const char __user *native;
408
409 #ifdef CONFIG_COMPAT
410         if (unlikely(argv.is_compat)) {
411                 compat_uptr_t compat;
412
413                 if (get_user(compat, argv.ptr.compat + nr))
414                         return ERR_PTR(-EFAULT);
415
416                 return compat_ptr(compat);
417         }
418 #endif
419
420         if (get_user(native, argv.ptr.native + nr))
421                 return ERR_PTR(-EFAULT);
422
423         return native;
424 }
425
426 /*
427  * count() counts the number of strings in array ARGV.
428  */
429 static int count(struct user_arg_ptr argv, int max)
430 {
431         int i = 0;
432
433         if (argv.ptr.native != NULL) {
434                 for (;;) {
435                         const char __user *p = get_user_arg_ptr(argv, i);
436
437                         if (!p)
438                                 break;
439
440                         if (IS_ERR(p))
441                                 return -EFAULT;
442
443                         if (i >= max)
444                                 return -E2BIG;
445                         ++i;
446
447                         if (fatal_signal_pending(current))
448                                 return -ERESTARTNOHAND;
449                         cond_resched();
450                 }
451         }
452         return i;
453 }
454
455 /*
456  * 'copy_strings()' copies argument/environment strings from the old
457  * processes's memory to the new process's stack.  The call to get_user_pages()
458  * ensures the destination page is created and not swapped out.
459  */
460 static int copy_strings(int argc, struct user_arg_ptr argv,
461                         struct linux_binprm *bprm)
462 {
463         struct page *kmapped_page = NULL;
464         char *kaddr = NULL;
465         unsigned long kpos = 0;
466         int ret;
467
468         while (argc-- > 0) {
469                 const char __user *str;
470                 int len;
471                 unsigned long pos;
472
473                 ret = -EFAULT;
474                 str = get_user_arg_ptr(argv, argc);
475                 if (IS_ERR(str))
476                         goto out;
477
478                 len = strnlen_user(str, MAX_ARG_STRLEN);
479                 if (!len)
480                         goto out;
481
482                 ret = -E2BIG;
483                 if (!valid_arg_len(bprm, len))
484                         goto out;
485
486                 /* We're going to work our way backwords. */
487                 pos = bprm->p;
488                 str += len;
489                 bprm->p -= len;
490
491                 while (len > 0) {
492                         int offset, bytes_to_copy;
493
494                         if (fatal_signal_pending(current)) {
495                                 ret = -ERESTARTNOHAND;
496                                 goto out;
497                         }
498                         cond_resched();
499
500                         offset = pos % PAGE_SIZE;
501                         if (offset == 0)
502                                 offset = PAGE_SIZE;
503
504                         bytes_to_copy = offset;
505                         if (bytes_to_copy > len)
506                                 bytes_to_copy = len;
507
508                         offset -= bytes_to_copy;
509                         pos -= bytes_to_copy;
510                         str -= bytes_to_copy;
511                         len -= bytes_to_copy;
512
513                         if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
514                                 struct page *page;
515
516                                 page = get_arg_page(bprm, pos, 1);
517                                 if (!page) {
518                                         ret = -E2BIG;
519                                         goto out;
520                                 }
521
522                                 if (kmapped_page) {
523                                         flush_kernel_dcache_page(kmapped_page);
524                                         kunmap(kmapped_page);
525                                         put_arg_page(kmapped_page);
526                                 }
527                                 kmapped_page = page;
528                                 kaddr = kmap(kmapped_page);
529                                 kpos = pos & PAGE_MASK;
530                                 flush_arg_page(bprm, kpos, kmapped_page);
531                         }
532                         if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
533                                 ret = -EFAULT;
534                                 goto out;
535                         }
536                 }
537         }
538         ret = 0;
539 out:
540         if (kmapped_page) {
541                 flush_kernel_dcache_page(kmapped_page);
542                 kunmap(kmapped_page);
543                 put_arg_page(kmapped_page);
544         }
545         return ret;
546 }
547
548 /*
549  * Like copy_strings, but get argv and its values from kernel memory.
550  */
551 int copy_strings_kernel(int argc, const char *const *__argv,
552                         struct linux_binprm *bprm)
553 {
554         int r;
555         mm_segment_t oldfs = get_fs();
556         struct user_arg_ptr argv = {
557                 .ptr.native = (const char __user *const  __user *)__argv,
558         };
559
560         set_fs(KERNEL_DS);
561         r = copy_strings(argc, argv, bprm);
562         set_fs(oldfs);
563
564         return r;
565 }
566 EXPORT_SYMBOL(copy_strings_kernel);
567
568 #ifdef CONFIG_MMU
569
570 /*
571  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
572  * the binfmt code determines where the new stack should reside, we shift it to
573  * its final location.  The process proceeds as follows:
574  *
575  * 1) Use shift to calculate the new vma endpoints.
576  * 2) Extend vma to cover both the old and new ranges.  This ensures the
577  *    arguments passed to subsequent functions are consistent.
578  * 3) Move vma's page tables to the new range.
579  * 4) Free up any cleared pgd range.
580  * 5) Shrink the vma to cover only the new range.
581  */
582 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
583 {
584         struct mm_struct *mm = vma->vm_mm;
585         unsigned long old_start = vma->vm_start;
586         unsigned long old_end = vma->vm_end;
587         unsigned long length = old_end - old_start;
588         unsigned long new_start = old_start - shift;
589         unsigned long new_end = old_end - shift;
590         struct mmu_gather tlb;
591
592         BUG_ON(new_start > new_end);
593
594         /*
595          * ensure there are no vmas between where we want to go
596          * and where we are
597          */
598         if (vma != find_vma(mm, new_start))
599                 return -EFAULT;
600
601         /*
602          * cover the whole range: [new_start, old_end)
603          */
604         if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
605                 return -ENOMEM;
606
607         /*
608          * move the page tables downwards, on failure we rely on
609          * process cleanup to remove whatever mess we made.
610          */
611         if (length != move_page_tables(vma, old_start,
612                                        vma, new_start, length, false))
613                 return -ENOMEM;
614
615         lru_add_drain();
616         tlb_gather_mmu(&tlb, mm, old_start, old_end);
617         if (new_end > old_start) {
618                 /*
619                  * when the old and new regions overlap clear from new_end.
620                  */
621                 free_pgd_range(&tlb, new_end, old_end, new_end,
622                         vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
623         } else {
624                 /*
625                  * otherwise, clean from old_start; this is done to not touch
626                  * the address space in [new_end, old_start) some architectures
627                  * have constraints on va-space that make this illegal (IA64) -
628                  * for the others its just a little faster.
629                  */
630                 free_pgd_range(&tlb, old_start, old_end, new_end,
631                         vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
632         }
633         tlb_finish_mmu(&tlb, old_start, old_end);
634
635         /*
636          * Shrink the vma to just the new range.  Always succeeds.
637          */
638         vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
639
640         return 0;
641 }
642
643 /*
644  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
645  * the stack is optionally relocated, and some extra space is added.
646  */
647 int setup_arg_pages(struct linux_binprm *bprm,
648                     unsigned long stack_top,
649                     int executable_stack)
650 {
651         unsigned long ret;
652         unsigned long stack_shift;
653         struct mm_struct *mm = current->mm;
654         struct vm_area_struct *vma = bprm->vma;
655         struct vm_area_struct *prev = NULL;
656         unsigned long vm_flags;
657         unsigned long stack_base;
658         unsigned long stack_size;
659         unsigned long stack_expand;
660         unsigned long rlim_stack;
661
662 #ifdef CONFIG_STACK_GROWSUP
663         /* Limit stack size */
664         stack_base = rlimit_max(RLIMIT_STACK);
665         if (stack_base > STACK_SIZE_MAX)
666                 stack_base = STACK_SIZE_MAX;
667
668         /* Add space for stack randomization. */
669         stack_base += (STACK_RND_MASK << PAGE_SHIFT);
670
671         /* Make sure we didn't let the argument array grow too large. */
672         if (vma->vm_end - vma->vm_start > stack_base)
673                 return -ENOMEM;
674
675         stack_base = PAGE_ALIGN(stack_top - stack_base);
676
677         stack_shift = vma->vm_start - stack_base;
678         mm->arg_start = bprm->p - stack_shift;
679         bprm->p = vma->vm_end - stack_shift;
680 #else
681         stack_top = arch_align_stack(stack_top);
682         stack_top = PAGE_ALIGN(stack_top);
683
684         if (unlikely(stack_top < mmap_min_addr) ||
685             unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
686                 return -ENOMEM;
687
688         stack_shift = vma->vm_end - stack_top;
689
690         bprm->p -= stack_shift;
691         mm->arg_start = bprm->p;
692 #endif
693
694         if (bprm->loader)
695                 bprm->loader -= stack_shift;
696         bprm->exec -= stack_shift;
697
698         down_write(&mm->mmap_sem);
699         vm_flags = VM_STACK_FLAGS;
700
701         /*
702          * Adjust stack execute permissions; explicitly enable for
703          * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
704          * (arch default) otherwise.
705          */
706         if (unlikely(executable_stack == EXSTACK_ENABLE_X))
707                 vm_flags |= VM_EXEC;
708         else if (executable_stack == EXSTACK_DISABLE_X)
709                 vm_flags &= ~VM_EXEC;
710         vm_flags |= mm->def_flags;
711         vm_flags |= VM_STACK_INCOMPLETE_SETUP;
712
713         ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
714                         vm_flags);
715         if (ret)
716                 goto out_unlock;
717         BUG_ON(prev != vma);
718
719         /* Move stack pages down in memory. */
720         if (stack_shift) {
721                 ret = shift_arg_pages(vma, stack_shift);
722                 if (ret)
723                         goto out_unlock;
724         }
725
726         /* mprotect_fixup is overkill to remove the temporary stack flags */
727         vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
728
729         stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
730         stack_size = vma->vm_end - vma->vm_start;
731         /*
732          * Align this down to a page boundary as expand_stack
733          * will align it up.
734          */
735         rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK;
736 #ifdef CONFIG_STACK_GROWSUP
737         if (stack_size + stack_expand > rlim_stack)
738                 stack_base = vma->vm_start + rlim_stack;
739         else
740                 stack_base = vma->vm_end + stack_expand;
741 #else
742         if (stack_size + stack_expand > rlim_stack)
743                 stack_base = vma->vm_end - rlim_stack;
744         else
745                 stack_base = vma->vm_start - stack_expand;
746 #endif
747         current->mm->start_stack = bprm->p;
748         ret = expand_stack(vma, stack_base);
749         if (ret)
750                 ret = -EFAULT;
751
752 out_unlock:
753         up_write(&mm->mmap_sem);
754         return ret;
755 }
756 EXPORT_SYMBOL(setup_arg_pages);
757
758 #endif /* CONFIG_MMU */
759
760 static struct file *do_open_execat(int fd, struct filename *name, int flags)
761 {
762         struct file *file;
763         int err;
764         struct open_flags open_exec_flags = {
765                 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
766                 .acc_mode = MAY_EXEC | MAY_OPEN,
767                 .intent = LOOKUP_OPEN,
768                 .lookup_flags = LOOKUP_FOLLOW,
769         };
770
771         if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
772                 return ERR_PTR(-EINVAL);
773         if (flags & AT_SYMLINK_NOFOLLOW)
774                 open_exec_flags.lookup_flags &= ~LOOKUP_FOLLOW;
775         if (flags & AT_EMPTY_PATH)
776                 open_exec_flags.lookup_flags |= LOOKUP_EMPTY;
777
778         file = do_filp_open(fd, name, &open_exec_flags);
779         if (IS_ERR(file))
780                 goto out;
781
782         err = -EACCES;
783         if (!S_ISREG(file_inode(file)->i_mode))
784                 goto exit;
785
786         if (path_noexec(&file->f_path))
787                 goto exit;
788
789         err = deny_write_access(file);
790         if (err)
791                 goto exit;
792
793         if (name->name[0] != '\0')
794                 fsnotify_open(file);
795
796 out:
797         return file;
798
799 exit:
800         fput(file);
801         return ERR_PTR(err);
802 }
803
804 struct file *open_exec(const char *name)
805 {
806         struct filename *filename = getname_kernel(name);
807         struct file *f = ERR_CAST(filename);
808
809         if (!IS_ERR(filename)) {
810                 f = do_open_execat(AT_FDCWD, filename, 0);
811                 putname(filename);
812         }
813         return f;
814 }
815 EXPORT_SYMBOL(open_exec);
816
817 int kernel_read(struct file *file, loff_t offset,
818                 char *addr, unsigned long count)
819 {
820         mm_segment_t old_fs;
821         loff_t pos = offset;
822         int result;
823
824         old_fs = get_fs();
825         set_fs(get_ds());
826         /* The cast to a user pointer is valid due to the set_fs() */
827         result = vfs_read(file, (void __user *)addr, count, &pos);
828         set_fs(old_fs);
829         return result;
830 }
831
832 EXPORT_SYMBOL(kernel_read);
833
834 ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)
835 {
836         ssize_t res = vfs_read(file, (void __user *)addr, len, &pos);
837         if (res > 0)
838                 flush_icache_range(addr, addr + len);
839         return res;
840 }
841 EXPORT_SYMBOL(read_code);
842
843 static int exec_mmap(struct mm_struct *mm)
844 {
845         struct task_struct *tsk;
846         struct mm_struct *old_mm, *active_mm;
847
848         /* Notify parent that we're no longer interested in the old VM */
849         tsk = current;
850         old_mm = current->mm;
851         mm_release(tsk, old_mm);
852
853         if (old_mm) {
854                 sync_mm_rss(old_mm);
855                 /*
856                  * Make sure that if there is a core dump in progress
857                  * for the old mm, we get out and die instead of going
858                  * through with the exec.  We must hold mmap_sem around
859                  * checking core_state and changing tsk->mm.
860                  */
861                 down_read(&old_mm->mmap_sem);
862                 if (unlikely(old_mm->core_state)) {
863                         up_read(&old_mm->mmap_sem);
864                         return -EINTR;
865                 }
866         }
867         task_lock(tsk);
868         active_mm = tsk->active_mm;
869         tsk->mm = mm;
870         tsk->active_mm = mm;
871         activate_mm(active_mm, mm);
872         tsk->mm->vmacache_seqnum = 0;
873         vmacache_flush(tsk);
874         task_unlock(tsk);
875         if (old_mm) {
876                 up_read(&old_mm->mmap_sem);
877                 BUG_ON(active_mm != old_mm);
878                 setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm);
879                 mm_update_next_owner(old_mm);
880                 mmput(old_mm);
881                 return 0;
882         }
883         mmdrop(active_mm);
884         return 0;
885 }
886
887 /*
888  * This function makes sure the current process has its own signal table,
889  * so that flush_signal_handlers can later reset the handlers without
890  * disturbing other processes.  (Other processes might share the signal
891  * table via the CLONE_SIGHAND option to clone().)
892  */
893 static int de_thread(struct task_struct *tsk)
894 {
895         struct signal_struct *sig = tsk->signal;
896         struct sighand_struct *oldsighand = tsk->sighand;
897         spinlock_t *lock = &oldsighand->siglock;
898
899         if (thread_group_empty(tsk))
900                 goto no_thread_group;
901
902         /*
903          * Kill all other threads in the thread group.
904          */
905         spin_lock_irq(lock);
906         if (signal_group_exit(sig)) {
907                 /*
908                  * Another group action in progress, just
909                  * return so that the signal is processed.
910                  */
911                 spin_unlock_irq(lock);
912                 return -EAGAIN;
913         }
914
915         sig->group_exit_task = tsk;
916         sig->notify_count = zap_other_threads(tsk);
917         if (!thread_group_leader(tsk))
918                 sig->notify_count--;
919
920         while (sig->notify_count) {
921                 __set_current_state(TASK_KILLABLE);
922                 spin_unlock_irq(lock);
923                 schedule();
924                 if (unlikely(__fatal_signal_pending(tsk)))
925                         goto killed;
926                 spin_lock_irq(lock);
927         }
928         spin_unlock_irq(lock);
929
930         /*
931          * At this point all other threads have exited, all we have to
932          * do is to wait for the thread group leader to become inactive,
933          * and to assume its PID:
934          */
935         if (!thread_group_leader(tsk)) {
936                 struct task_struct *leader = tsk->group_leader;
937
938                 for (;;) {
939                         threadgroup_change_begin(tsk);
940                         write_lock_irq(&tasklist_lock);
941                         /*
942                          * Do this under tasklist_lock to ensure that
943                          * exit_notify() can't miss ->group_exit_task
944                          */
945                         sig->notify_count = -1;
946                         if (likely(leader->exit_state))
947                                 break;
948                         __set_current_state(TASK_KILLABLE);
949                         write_unlock_irq(&tasklist_lock);
950                         threadgroup_change_end(tsk);
951                         schedule();
952                         if (unlikely(__fatal_signal_pending(tsk)))
953                                 goto killed;
954                 }
955
956                 /*
957                  * The only record we have of the real-time age of a
958                  * process, regardless of execs it's done, is start_time.
959                  * All the past CPU time is accumulated in signal_struct
960                  * from sister threads now dead.  But in this non-leader
961                  * exec, nothing survives from the original leader thread,
962                  * whose birth marks the true age of this process now.
963                  * When we take on its identity by switching to its PID, we
964                  * also take its birthdate (always earlier than our own).
965                  */
966                 tsk->start_time = leader->start_time;
967                 tsk->real_start_time = leader->real_start_time;
968
969                 BUG_ON(!same_thread_group(leader, tsk));
970                 BUG_ON(has_group_leader_pid(tsk));
971                 /*
972                  * An exec() starts a new thread group with the
973                  * TGID of the previous thread group. Rehash the
974                  * two threads with a switched PID, and release
975                  * the former thread group leader:
976                  */
977
978                 /* Become a process group leader with the old leader's pid.
979                  * The old leader becomes a thread of the this thread group.
980                  * Note: The old leader also uses this pid until release_task
981                  *       is called.  Odd but simple and correct.
982                  */
983                 tsk->pid = leader->pid;
984                 change_pid(tsk, PIDTYPE_PID, task_pid(leader));
985                 transfer_pid(leader, tsk, PIDTYPE_PGID);
986                 transfer_pid(leader, tsk, PIDTYPE_SID);
987
988                 list_replace_rcu(&leader->tasks, &tsk->tasks);
989                 list_replace_init(&leader->sibling, &tsk->sibling);
990
991                 tsk->group_leader = tsk;
992                 leader->group_leader = tsk;
993
994                 tsk->exit_signal = SIGCHLD;
995                 leader->exit_signal = -1;
996
997                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
998                 leader->exit_state = EXIT_DEAD;
999
1000                 /*
1001                  * We are going to release_task()->ptrace_unlink() silently,
1002                  * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
1003                  * the tracer wont't block again waiting for this thread.
1004                  */
1005                 if (unlikely(leader->ptrace))
1006                         __wake_up_parent(leader, leader->parent);
1007                 write_unlock_irq(&tasklist_lock);
1008                 threadgroup_change_end(tsk);
1009
1010                 release_task(leader);
1011         }
1012
1013         sig->group_exit_task = NULL;
1014         sig->notify_count = 0;
1015
1016 no_thread_group:
1017         /* we have changed execution domain */
1018         tsk->exit_signal = SIGCHLD;
1019
1020         exit_itimers(sig);
1021         flush_itimer_signals();
1022
1023         if (atomic_read(&oldsighand->count) != 1) {
1024                 struct sighand_struct *newsighand;
1025                 /*
1026                  * This ->sighand is shared with the CLONE_SIGHAND
1027                  * but not CLONE_THREAD task, switch to the new one.
1028                  */
1029                 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1030                 if (!newsighand)
1031                         return -ENOMEM;
1032
1033                 atomic_set(&newsighand->count, 1);
1034                 memcpy(newsighand->action, oldsighand->action,
1035                        sizeof(newsighand->action));
1036
1037                 write_lock_irq(&tasklist_lock);
1038                 spin_lock(&oldsighand->siglock);
1039                 rcu_assign_pointer(tsk->sighand, newsighand);
1040                 spin_unlock(&oldsighand->siglock);
1041                 write_unlock_irq(&tasklist_lock);
1042
1043                 __cleanup_sighand(oldsighand);
1044         }
1045
1046         BUG_ON(!thread_group_leader(tsk));
1047         return 0;
1048
1049 killed:
1050         /* protects against exit_notify() and __exit_signal() */
1051         read_lock(&tasklist_lock);
1052         sig->group_exit_task = NULL;
1053         sig->notify_count = 0;
1054         read_unlock(&tasklist_lock);
1055         return -EAGAIN;
1056 }
1057
1058 char *get_task_comm(char *buf, struct task_struct *tsk)
1059 {
1060         /* buf must be at least sizeof(tsk->comm) in size */
1061         task_lock(tsk);
1062         strncpy(buf, tsk->comm, sizeof(tsk->comm));
1063         task_unlock(tsk);
1064         return buf;
1065 }
1066 EXPORT_SYMBOL_GPL(get_task_comm);
1067
1068 /*
1069  * These functions flushes out all traces of the currently running executable
1070  * so that a new one can be started
1071  */
1072
1073 void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)
1074 {
1075         task_lock(tsk);
1076         trace_task_rename(tsk, buf);
1077         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
1078         task_unlock(tsk);
1079         perf_event_comm(tsk, exec);
1080 }
1081
1082 int flush_old_exec(struct linux_binprm * bprm)
1083 {
1084         int retval;
1085
1086         /*
1087          * Make sure we have a private signal table and that
1088          * we are unassociated from the previous thread group.
1089          */
1090         retval = de_thread(current);
1091         if (retval)
1092                 goto out;
1093
1094         /*
1095          * Must be called _before_ exec_mmap() as bprm->mm is
1096          * not visibile until then. This also enables the update
1097          * to be lockless.
1098          */
1099         set_mm_exe_file(bprm->mm, bprm->file);
1100
1101         /*
1102          * Release all of the old mmap stuff
1103          */
1104         acct_arg_size(bprm, 0);
1105         retval = exec_mmap(bprm->mm);
1106         if (retval)
1107                 goto out;
1108
1109         bprm->mm = NULL;                /* We're using it now */
1110
1111         set_fs(USER_DS);
1112         current->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD |
1113                                         PF_NOFREEZE | PF_NO_SETAFFINITY);
1114         flush_thread();
1115         current->personality &= ~bprm->per_clear;
1116
1117         return 0;
1118
1119 out:
1120         return retval;
1121 }
1122 EXPORT_SYMBOL(flush_old_exec);
1123
1124 void would_dump(struct linux_binprm *bprm, struct file *file)
1125 {
1126         if (inode_permission(file_inode(file), MAY_READ) < 0)
1127                 bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
1128 }
1129 EXPORT_SYMBOL(would_dump);
1130
1131 void setup_new_exec(struct linux_binprm * bprm)
1132 {
1133         arch_pick_mmap_layout(current->mm);
1134
1135         /* This is the point of no return */
1136         current->sas_ss_sp = current->sas_ss_size = 0;
1137
1138         if (uid_eq(current_euid(), current_uid()) && gid_eq(current_egid(), current_gid()))
1139                 set_dumpable(current->mm, SUID_DUMP_USER);
1140         else
1141                 set_dumpable(current->mm, suid_dumpable);
1142
1143         perf_event_exec();
1144         __set_task_comm(current, kbasename(bprm->filename), true);
1145
1146         /* Set the new mm task size. We have to do that late because it may
1147          * depend on TIF_32BIT which is only updated in flush_thread() on
1148          * some architectures like powerpc
1149          */
1150         current->mm->task_size = TASK_SIZE;
1151
1152         /* install the new credentials */
1153         if (!uid_eq(bprm->cred->uid, current_euid()) ||
1154             !gid_eq(bprm->cred->gid, current_egid())) {
1155                 current->pdeath_signal = 0;
1156         } else {
1157                 would_dump(bprm, bprm->file);
1158                 if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)
1159                         set_dumpable(current->mm, suid_dumpable);
1160         }
1161
1162         /* An exec changes our domain. We are no longer part of the thread
1163            group */
1164         current->self_exec_id++;
1165         flush_signal_handlers(current, 0);
1166         do_close_on_exec(current->files);
1167 }
1168 EXPORT_SYMBOL(setup_new_exec);
1169
1170 /*
1171  * Prepare credentials and lock ->cred_guard_mutex.
1172  * install_exec_creds() commits the new creds and drops the lock.
1173  * Or, if exec fails before, free_bprm() should release ->cred and
1174  * and unlock.
1175  */
1176 int prepare_bprm_creds(struct linux_binprm *bprm)
1177 {
1178         if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1179                 return -ERESTARTNOINTR;
1180
1181         bprm->cred = prepare_exec_creds();
1182         if (likely(bprm->cred))
1183                 return 0;
1184
1185         mutex_unlock(&current->signal->cred_guard_mutex);
1186         return -ENOMEM;
1187 }
1188
1189 static void free_bprm(struct linux_binprm *bprm)
1190 {
1191         free_arg_pages(bprm);
1192         if (bprm->cred) {
1193                 mutex_unlock(&current->signal->cred_guard_mutex);
1194                 abort_creds(bprm->cred);
1195         }
1196         if (bprm->file) {
1197                 allow_write_access(bprm->file);
1198                 fput(bprm->file);
1199         }
1200         /* If a binfmt changed the interp, free it. */
1201         if (bprm->interp != bprm->filename)
1202                 kfree(bprm->interp);
1203         kfree(bprm);
1204 }
1205
1206 int bprm_change_interp(char *interp, struct linux_binprm *bprm)
1207 {
1208         /* If a binfmt changed the interp, free it first. */
1209         if (bprm->interp != bprm->filename)
1210                 kfree(bprm->interp);
1211         bprm->interp = kstrdup(interp, GFP_KERNEL);
1212         if (!bprm->interp)
1213                 return -ENOMEM;
1214         return 0;
1215 }
1216 EXPORT_SYMBOL(bprm_change_interp);
1217
1218 /*
1219  * install the new credentials for this executable
1220  */
1221 void install_exec_creds(struct linux_binprm *bprm)
1222 {
1223         security_bprm_committing_creds(bprm);
1224
1225         commit_creds(bprm->cred);
1226         bprm->cred = NULL;
1227
1228         /*
1229          * Disable monitoring for regular users
1230          * when executing setuid binaries. Must
1231          * wait until new credentials are committed
1232          * by commit_creds() above
1233          */
1234         if (get_dumpable(current->mm) != SUID_DUMP_USER)
1235                 perf_event_exit_task(current);
1236         /*
1237          * cred_guard_mutex must be held at least to this point to prevent
1238          * ptrace_attach() from altering our determination of the task's
1239          * credentials; any time after this it may be unlocked.
1240          */
1241         security_bprm_committed_creds(bprm);
1242         mutex_unlock(&current->signal->cred_guard_mutex);
1243 }
1244 EXPORT_SYMBOL(install_exec_creds);
1245
1246 /*
1247  * determine how safe it is to execute the proposed program
1248  * - the caller must hold ->cred_guard_mutex to protect against
1249  *   PTRACE_ATTACH or seccomp thread-sync
1250  */
1251 static void check_unsafe_exec(struct linux_binprm *bprm)
1252 {
1253         struct task_struct *p = current, *t;
1254         unsigned n_fs;
1255
1256         if (p->ptrace) {
1257                 if (p->ptrace & PT_PTRACE_CAP)
1258                         bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP;
1259                 else
1260                         bprm->unsafe |= LSM_UNSAFE_PTRACE;
1261         }
1262
1263         /*
1264          * This isn't strictly necessary, but it makes it harder for LSMs to
1265          * mess up.
1266          */
1267         if (task_no_new_privs(current))
1268                 bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS;
1269
1270         t = p;
1271         n_fs = 1;
1272         spin_lock(&p->fs->lock);
1273         rcu_read_lock();
1274         while_each_thread(p, t) {
1275                 if (t->fs == p->fs)
1276                         n_fs++;
1277         }
1278         rcu_read_unlock();
1279
1280         if (p->fs->users > n_fs)
1281                 bprm->unsafe |= LSM_UNSAFE_SHARE;
1282         else
1283                 p->fs->in_exec = 1;
1284         spin_unlock(&p->fs->lock);
1285 }
1286
1287 static void bprm_fill_uid(struct linux_binprm *bprm)
1288 {
1289         struct inode *inode;
1290         unsigned int mode;
1291         kuid_t uid;
1292         kgid_t gid;
1293
1294         /* clear any previous set[ug]id data from a previous binary */
1295         bprm->cred->euid = current_euid();
1296         bprm->cred->egid = current_egid();
1297
1298         if (bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)
1299                 return;
1300
1301         if (task_no_new_privs(current))
1302                 return;
1303
1304         inode = file_inode(bprm->file);
1305         mode = READ_ONCE(inode->i_mode);
1306         if (!(mode & (S_ISUID|S_ISGID)))
1307                 return;
1308
1309         /* Be careful if suid/sgid is set */
1310         mutex_lock(&inode->i_mutex);
1311
1312         /* reload atomically mode/uid/gid now that lock held */
1313         mode = inode->i_mode;
1314         uid = inode->i_uid;
1315         gid = inode->i_gid;
1316         mutex_unlock(&inode->i_mutex);
1317
1318         /* We ignore suid/sgid if there are no mappings for them in the ns */
1319         if (!kuid_has_mapping(bprm->cred->user_ns, uid) ||
1320                  !kgid_has_mapping(bprm->cred->user_ns, gid))
1321                 return;
1322
1323         if (mode & S_ISUID) {
1324                 bprm->per_clear |= PER_CLEAR_ON_SETID;
1325                 bprm->cred->euid = uid;
1326         }
1327
1328         if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1329                 bprm->per_clear |= PER_CLEAR_ON_SETID;
1330                 bprm->cred->egid = gid;
1331         }
1332 }
1333
1334 /*
1335  * Fill the binprm structure from the inode.
1336  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1337  *
1338  * This may be called multiple times for binary chains (scripts for example).
1339  */
1340 int prepare_binprm(struct linux_binprm *bprm)
1341 {
1342         int retval;
1343
1344         bprm_fill_uid(bprm);
1345
1346         /* fill in binprm security blob */
1347         retval = security_bprm_set_creds(bprm);
1348         if (retval)
1349                 return retval;
1350         bprm->cred_prepared = 1;
1351
1352         memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1353         return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1354 }
1355
1356 EXPORT_SYMBOL(prepare_binprm);
1357
1358 /*
1359  * Arguments are '\0' separated strings found at the location bprm->p
1360  * points to; chop off the first by relocating brpm->p to right after
1361  * the first '\0' encountered.
1362  */
1363 int remove_arg_zero(struct linux_binprm *bprm)
1364 {
1365         int ret = 0;
1366         unsigned long offset;
1367         char *kaddr;
1368         struct page *page;
1369
1370         if (!bprm->argc)
1371                 return 0;
1372
1373         do {
1374                 offset = bprm->p & ~PAGE_MASK;
1375                 page = get_arg_page(bprm, bprm->p, 0);
1376                 if (!page) {
1377                         ret = -EFAULT;
1378                         goto out;
1379                 }
1380                 kaddr = kmap_atomic(page);
1381
1382                 for (; offset < PAGE_SIZE && kaddr[offset];
1383                                 offset++, bprm->p++)
1384                         ;
1385
1386                 kunmap_atomic(kaddr);
1387                 put_arg_page(page);
1388
1389                 if (offset == PAGE_SIZE)
1390                         free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1391         } while (offset == PAGE_SIZE);
1392
1393         bprm->p++;
1394         bprm->argc--;
1395         ret = 0;
1396
1397 out:
1398         return ret;
1399 }
1400 EXPORT_SYMBOL(remove_arg_zero);
1401
1402 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1403 /*
1404  * cycle the list of binary formats handler, until one recognizes the image
1405  */
1406 int search_binary_handler(struct linux_binprm *bprm)
1407 {
1408         bool need_retry = IS_ENABLED(CONFIG_MODULES);
1409         struct linux_binfmt *fmt;
1410         int retval;
1411
1412         /* This allows 4 levels of binfmt rewrites before failing hard. */
1413         if (bprm->recursion_depth > 5)
1414                 return -ELOOP;
1415
1416         retval = security_bprm_check(bprm);
1417         if (retval)
1418                 return retval;
1419
1420         retval = -ENOENT;
1421  retry:
1422         read_lock(&binfmt_lock);
1423         list_for_each_entry(fmt, &formats, lh) {
1424                 if (!try_module_get(fmt->module))
1425                         continue;
1426                 read_unlock(&binfmt_lock);
1427                 bprm->recursion_depth++;
1428                 retval = fmt->load_binary(bprm);
1429                 read_lock(&binfmt_lock);
1430                 put_binfmt(fmt);
1431                 bprm->recursion_depth--;
1432                 if (retval < 0 && !bprm->mm) {
1433                         /* we got to flush_old_exec() and failed after it */
1434                         read_unlock(&binfmt_lock);
1435                         force_sigsegv(SIGSEGV, current);
1436                         return retval;
1437                 }
1438                 if (retval != -ENOEXEC || !bprm->file) {
1439                         read_unlock(&binfmt_lock);
1440                         return retval;
1441                 }
1442         }
1443         read_unlock(&binfmt_lock);
1444
1445         if (need_retry) {
1446                 if (printable(bprm->buf[0]) && printable(bprm->buf[1]) &&
1447                     printable(bprm->buf[2]) && printable(bprm->buf[3]))
1448                         return retval;
1449                 if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0)
1450                         return retval;
1451                 need_retry = false;
1452                 goto retry;
1453         }
1454
1455         return retval;
1456 }
1457 EXPORT_SYMBOL(search_binary_handler);
1458
1459 static int exec_binprm(struct linux_binprm *bprm)
1460 {
1461         pid_t old_pid, old_vpid;
1462         int ret;
1463
1464         /* Need to fetch pid before load_binary changes it */
1465         old_pid = current->pid;
1466         rcu_read_lock();
1467         old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1468         rcu_read_unlock();
1469
1470         ret = search_binary_handler(bprm);
1471         if (ret >= 0) {
1472                 audit_bprm(bprm);
1473                 trace_sched_process_exec(current, old_pid, bprm);
1474                 ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
1475                 proc_exec_connector(current);
1476         }
1477
1478         return ret;
1479 }
1480
1481 /*
1482  * sys_execve() executes a new program.
1483  */
1484 static int do_execveat_common(int fd, struct filename *filename,
1485                               struct user_arg_ptr argv,
1486                               struct user_arg_ptr envp,
1487                               int flags)
1488 {
1489         char *pathbuf = NULL;
1490         struct linux_binprm *bprm;
1491         struct file *file;
1492         struct files_struct *displaced;
1493         int retval;
1494
1495         if (IS_ERR(filename))
1496                 return PTR_ERR(filename);
1497
1498         /*
1499          * We move the actual failure in case of RLIMIT_NPROC excess from
1500          * set*uid() to execve() because too many poorly written programs
1501          * don't check setuid() return code.  Here we additionally recheck
1502          * whether NPROC limit is still exceeded.
1503          */
1504         if ((current->flags & PF_NPROC_EXCEEDED) &&
1505             atomic_read(&current_user()->processes) > rlimit(RLIMIT_NPROC)) {
1506                 retval = -EAGAIN;
1507                 goto out_ret;
1508         }
1509
1510         /* We're below the limit (still or again), so we don't want to make
1511          * further execve() calls fail. */
1512         current->flags &= ~PF_NPROC_EXCEEDED;
1513
1514         retval = unshare_files(&displaced);
1515         if (retval)
1516                 goto out_ret;
1517
1518         retval = -ENOMEM;
1519         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1520         if (!bprm)
1521                 goto out_files;
1522
1523         retval = prepare_bprm_creds(bprm);
1524         if (retval)
1525                 goto out_free;
1526
1527         check_unsafe_exec(bprm);
1528         current->in_execve = 1;
1529
1530         file = do_open_execat(fd, filename, flags);
1531         retval = PTR_ERR(file);
1532         if (IS_ERR(file))
1533                 goto out_unmark;
1534
1535         sched_exec();
1536
1537         bprm->file = file;
1538         if (fd == AT_FDCWD || filename->name[0] == '/') {
1539                 bprm->filename = filename->name;
1540         } else {
1541                 if (filename->name[0] == '\0')
1542                         pathbuf = kasprintf(GFP_TEMPORARY, "/dev/fd/%d", fd);
1543                 else
1544                         pathbuf = kasprintf(GFP_TEMPORARY, "/dev/fd/%d/%s",
1545                                             fd, filename->name);
1546                 if (!pathbuf) {
1547                         retval = -ENOMEM;
1548                         goto out_unmark;
1549                 }
1550                 /*
1551                  * Record that a name derived from an O_CLOEXEC fd will be
1552                  * inaccessible after exec. Relies on having exclusive access to
1553                  * current->files (due to unshare_files above).
1554                  */
1555                 if (close_on_exec(fd, rcu_dereference_raw(current->files->fdt)))
1556                         bprm->interp_flags |= BINPRM_FLAGS_PATH_INACCESSIBLE;
1557                 bprm->filename = pathbuf;
1558         }
1559         bprm->interp = bprm->filename;
1560
1561         retval = bprm_mm_init(bprm);
1562         if (retval)
1563                 goto out_unmark;
1564
1565         bprm->argc = count(argv, MAX_ARG_STRINGS);
1566         if ((retval = bprm->argc) < 0)
1567                 goto out;
1568
1569         bprm->envc = count(envp, MAX_ARG_STRINGS);
1570         if ((retval = bprm->envc) < 0)
1571                 goto out;
1572
1573         retval = prepare_binprm(bprm);
1574         if (retval < 0)
1575                 goto out;
1576
1577         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1578         if (retval < 0)
1579                 goto out;
1580
1581         bprm->exec = bprm->p;
1582         retval = copy_strings(bprm->envc, envp, bprm);
1583         if (retval < 0)
1584                 goto out;
1585
1586         retval = copy_strings(bprm->argc, argv, bprm);
1587         if (retval < 0)
1588                 goto out;
1589
1590         retval = exec_binprm(bprm);
1591         if (retval < 0)
1592                 goto out;
1593
1594         /* execve succeeded */
1595         current->fs->in_exec = 0;
1596         current->in_execve = 0;
1597         acct_update_integrals(current);
1598         task_numa_free(current);
1599         free_bprm(bprm);
1600         kfree(pathbuf);
1601         putname(filename);
1602         if (displaced)
1603                 put_files_struct(displaced);
1604         return retval;
1605
1606 out:
1607         if (bprm->mm) {
1608                 acct_arg_size(bprm, 0);
1609                 mmput(bprm->mm);
1610         }
1611
1612 out_unmark:
1613         current->fs->in_exec = 0;
1614         current->in_execve = 0;
1615
1616 out_free:
1617         free_bprm(bprm);
1618         kfree(pathbuf);
1619
1620 out_files:
1621         if (displaced)
1622                 reset_files_struct(displaced);
1623 out_ret:
1624         putname(filename);
1625         return retval;
1626 }
1627
1628 int do_execve(struct filename *filename,
1629         const char __user *const __user *__argv,
1630         const char __user *const __user *__envp)
1631 {
1632         struct user_arg_ptr argv = { .ptr.native = __argv };
1633         struct user_arg_ptr envp = { .ptr.native = __envp };
1634         return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
1635 }
1636
1637 int do_execveat(int fd, struct filename *filename,
1638                 const char __user *const __user *__argv,
1639                 const char __user *const __user *__envp,
1640                 int flags)
1641 {
1642         struct user_arg_ptr argv = { .ptr.native = __argv };
1643         struct user_arg_ptr envp = { .ptr.native = __envp };
1644
1645         return do_execveat_common(fd, filename, argv, envp, flags);
1646 }
1647
1648 #ifdef CONFIG_COMPAT
1649 static int compat_do_execve(struct filename *filename,
1650         const compat_uptr_t __user *__argv,
1651         const compat_uptr_t __user *__envp)
1652 {
1653         struct user_arg_ptr argv = {
1654                 .is_compat = true,
1655                 .ptr.compat = __argv,
1656         };
1657         struct user_arg_ptr envp = {
1658                 .is_compat = true,
1659                 .ptr.compat = __envp,
1660         };
1661         return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
1662 }
1663
1664 static int compat_do_execveat(int fd, struct filename *filename,
1665                               const compat_uptr_t __user *__argv,
1666                               const compat_uptr_t __user *__envp,
1667                               int flags)
1668 {
1669         struct user_arg_ptr argv = {
1670                 .is_compat = true,
1671                 .ptr.compat = __argv,
1672         };
1673         struct user_arg_ptr envp = {
1674                 .is_compat = true,
1675                 .ptr.compat = __envp,
1676         };
1677         return do_execveat_common(fd, filename, argv, envp, flags);
1678 }
1679 #endif
1680
1681 void set_binfmt(struct linux_binfmt *new)
1682 {
1683         struct mm_struct *mm = current->mm;
1684
1685         if (mm->binfmt)
1686                 module_put(mm->binfmt->module);
1687
1688         mm->binfmt = new;
1689         if (new)
1690                 __module_get(new->module);
1691 }
1692 EXPORT_SYMBOL(set_binfmt);
1693
1694 /*
1695  * set_dumpable stores three-value SUID_DUMP_* into mm->flags.
1696  */
1697 void set_dumpable(struct mm_struct *mm, int value)
1698 {
1699         unsigned long old, new;
1700
1701         if (WARN_ON((unsigned)value > SUID_DUMP_ROOT))
1702                 return;
1703
1704         do {
1705                 old = ACCESS_ONCE(mm->flags);
1706                 new = (old & ~MMF_DUMPABLE_MASK) | value;
1707         } while (cmpxchg(&mm->flags, old, new) != old);
1708 }
1709
1710 SYSCALL_DEFINE3(execve,
1711                 const char __user *, filename,
1712                 const char __user *const __user *, argv,
1713                 const char __user *const __user *, envp)
1714 {
1715         return do_execve(getname(filename), argv, envp);
1716 }
1717
1718 SYSCALL_DEFINE5(execveat,
1719                 int, fd, const char __user *, filename,
1720                 const char __user *const __user *, argv,
1721                 const char __user *const __user *, envp,
1722                 int, flags)
1723 {
1724         int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
1725
1726         return do_execveat(fd,
1727                            getname_flags(filename, lookup_flags, NULL),
1728                            argv, envp, flags);
1729 }
1730
1731 #ifdef CONFIG_COMPAT
1732 COMPAT_SYSCALL_DEFINE3(execve, const char __user *, filename,
1733         const compat_uptr_t __user *, argv,
1734         const compat_uptr_t __user *, envp)
1735 {
1736         return compat_do_execve(getname(filename), argv, envp);
1737 }
1738
1739 COMPAT_SYSCALL_DEFINE5(execveat, int, fd,
1740                        const char __user *, filename,
1741                        const compat_uptr_t __user *, argv,
1742                        const compat_uptr_t __user *, envp,
1743                        int,  flags)
1744 {
1745         int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
1746
1747         return compat_do_execveat(fd,
1748                                   getname_flags(filename, lookup_flags, NULL),
1749                                   argv, envp, flags);
1750 }
1751 #endif