| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * linux/fs/exec.c |
| * |
| * Copyright (C) 1991, 1992 Linus Torvalds |
| */ |
| |
| /* |
| * #!-checking implemented by tytso. |
| */ |
| /* |
| * Demand-loading implemented 01.12.91 - no need to read anything but |
| * the header into memory. The inode of the executable is put into |
| * "current->executable", and page faults do the actual loading. Clean. |
| * |
| * Once more I can proudly say that linux stood up to being changed: it |
| * was less than 2 hours work to get demand-loading completely implemented. |
| * |
| * Demand loading changed July 1993 by Eric Youngdale. Use mmap instead, |
| * current->executable is only used by the procfs. This allows a dispatch |
| * table to check for several different types of binary formats. We keep |
| * trying until we recognize the file or we run out of supported binary |
| * formats. |
| */ |
| |
| #include <linux/kernel_read_file.h> |
| #include <linux/slab.h> |
| #include <linux/file.h> |
| #include <linux/fdtable.h> |
| #include <linux/mm.h> |
| #include <linux/stat.h> |
| #include <linux/fcntl.h> |
| #include <linux/swap.h> |
| #include <linux/string.h> |
| #include <linux/init.h> |
| #include <linux/sched/mm.h> |
| #include <linux/sched/coredump.h> |
| #include <linux/sched/signal.h> |
| #include <linux/sched/numa_balancing.h> |
| #include <linux/sched/task.h> |
| #include <linux/pagemap.h> |
| #include <linux/perf_event.h> |
| #include <linux/highmem.h> |
| #include <linux/spinlock.h> |
| #include <linux/key.h> |
| #include <linux/personality.h> |
| #include <linux/binfmts.h> |
| #include <linux/utsname.h> |
| #include <linux/pid_namespace.h> |
| #include <linux/module.h> |
| #include <linux/namei.h> |
| #include <linux/mount.h> |
| #include <linux/security.h> |
| #include <linux/syscalls.h> |
| #include <linux/tsacct_kern.h> |
| #include <linux/cn_proc.h> |
| #include <linux/audit.h> |
| #include <linux/kmod.h> |
| #include <linux/fsnotify.h> |
| #include <linux/fs_struct.h> |
| #include <linux/oom.h> |
| #include <linux/compat.h> |
| #include <linux/vmalloc.h> |
| #include <linux/io_uring.h> |
| #include <linux/syscall_user_dispatch.h> |
| #include <linux/coredump.h> |
| |
| #include <linux/uaccess.h> |
| #include <asm/mmu_context.h> |
| #include <asm/tlb.h> |
| |
| #include <trace/events/task.h> |
| #include "internal.h" |
| |
| #include <trace/events/sched.h> |
| |
| static int bprm_creds_from_file(struct linux_binprm *bprm); |
| |
| int suid_dumpable = 0; |
| |
| static LIST_HEAD(formats); |
| static DEFINE_RWLOCK(binfmt_lock); |
| |
| void __register_binfmt(struct linux_binfmt * fmt, int insert) |
| { |
| write_lock(&binfmt_lock); |
| insert ? list_add(&fmt->lh, &formats) : |
| list_add_tail(&fmt->lh, &formats); |
| write_unlock(&binfmt_lock); |
| } |
| |
| EXPORT_SYMBOL(__register_binfmt); |
| |
| void unregister_binfmt(struct linux_binfmt * fmt) |
| { |
| write_lock(&binfmt_lock); |
| list_del(&fmt->lh); |
| write_unlock(&binfmt_lock); |
| } |
| |
| EXPORT_SYMBOL(unregister_binfmt); |
| |
| static inline void put_binfmt(struct linux_binfmt * fmt) |
| { |
| module_put(fmt->module); |
| } |
| |
| bool path_noexec(const struct path *path) |
| { |
| return (path->mnt->mnt_flags & MNT_NOEXEC) || |
| (path->mnt->mnt_sb->s_iflags & SB_I_NOEXEC); |
| } |
| |
| #ifdef CONFIG_USELIB |
| /* |
| * Note that a shared library must be both readable and executable due to |
| * security reasons. |
| * |
| * Also note that we take the address to load from the file itself. |
| */ |
| SYSCALL_DEFINE1(uselib, const char __user *, library) |
| { |
| struct linux_binfmt *fmt; |
| struct file *file; |
| struct filename *tmp = getname(library); |
| int error = PTR_ERR(tmp); |
| static const struct open_flags uselib_flags = { |
| .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC, |
| .acc_mode = MAY_READ | MAY_EXEC, |
| .intent = LOOKUP_OPEN, |
| .lookup_flags = LOOKUP_FOLLOW, |
| }; |
| |
| if (IS_ERR(tmp)) |
| goto out; |
| |
| file = do_filp_open(AT_FDCWD, tmp, &uselib_flags); |
| putname(tmp); |
| error = PTR_ERR(file); |
| if (IS_ERR(file)) |
| goto out; |
| |
| /* |
| * may_open() has already checked for this, so it should be |
| * impossible to trip now. But we need to be extra cautious |
| * and check again at the very end too. |
| */ |
| error = -EACCES; |
| if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) || |
| path_noexec(&file->f_path))) |
| goto exit; |
| |
| fsnotify_open(file); |
| |
| error = -ENOEXEC; |
| |
| read_lock(&binfmt_lock); |
| list_for_each_entry(fmt, &formats, lh) { |
| if (!fmt->load_shlib) |
| continue; |
| if (!try_module_get(fmt->module)) |
| continue; |
| read_unlock(&binfmt_lock); |
| error = fmt->load_shlib(file); |
| read_lock(&binfmt_lock); |
| put_binfmt(fmt); |
| if (error != -ENOEXEC) |
| break; |
| } |
| read_unlock(&binfmt_lock); |
| exit: |
| fput(file); |
| out: |
| return error; |
| } |
| #endif /* #ifdef CONFIG_USELIB */ |
| |
| #ifdef CONFIG_MMU |
| /* |
| * The nascent bprm->mm is not visible until exec_mmap() but it can |
| * use a lot of memory, account these pages in current->mm temporary |
| * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we |
| * change the counter back via acct_arg_size(0). |
| */ |
| static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages) |
| { |
| struct mm_struct *mm = current->mm; |
| long diff = (long)(pages - bprm->vma_pages); |
| |
| if (!mm || !diff) |
| return; |
| |
| bprm->vma_pages = pages; |
| add_mm_counter(mm, MM_ANONPAGES, diff); |
| } |
| |
| static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, |
| int write) |
| { |
| struct page *page; |
| struct vm_area_struct *vma = bprm->vma; |
| struct mm_struct *mm = bprm->mm; |
| int ret; |
| |
| /* |
| * Avoid relying on expanding the stack down in GUP (which |
| * does not work for STACK_GROWSUP anyway), and just do it |
| * by hand ahead of time. |
| */ |
| if (write && pos < vma->vm_start) { |
| mmap_write_lock(mm); |
| ret = expand_downwards(vma, pos); |
| if (unlikely(ret < 0)) { |
| mmap_write_unlock(mm); |
| return NULL; |
| } |
| mmap_write_downgrade(mm); |
| } else |
| mmap_read_lock(mm); |
| |
| /* |
| * We are doing an exec(). 'current' is the process |
| * doing the exec and 'mm' is the new process's mm. |
| */ |
| ret = get_user_pages_remote(mm, pos, 1, |
| write ? FOLL_WRITE : 0, |
| &page, NULL, NULL); |
| mmap_read_unlock(mm); |
| if (ret <= 0) |
| return NULL; |
| |
| if (write) |
| acct_arg_size(bprm, vma_pages(vma)); |
| |
| return page; |
| } |
| |
| static void put_arg_page(struct page *page) |
| { |
| put_page(page); |
| } |
| |
| static void free_arg_pages(struct linux_binprm *bprm) |
| { |
| } |
| |
| static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, |
| struct page *page) |
| { |
| flush_cache_page(bprm->vma, pos, page_to_pfn(page)); |
| } |
| |
| static int __bprm_mm_init(struct linux_binprm *bprm) |
| { |
| int err; |
| struct vm_area_struct *vma = NULL; |
| struct mm_struct *mm = bprm->mm; |
| |
| bprm->vma = vma = vm_area_alloc(mm); |
| if (!vma) |
| return -ENOMEM; |
| vma_set_anonymous(vma); |
| |
| if (mmap_write_lock_killable(mm)) { |
| err = -EINTR; |
| goto err_free; |
| } |
| |
| /* |
| * Place the stack at the largest stack address the architecture |
| * supports. Later, we'll move this to an appropriate place. We don't |
| * use STACK_TOP because that can depend on attributes which aren't |
| * configured yet. |
| */ |
| BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP); |
| vma->vm_end = STACK_TOP_MAX; |
| vma->vm_start = vma->vm_end - PAGE_SIZE; |
| vm_flags_init(vma, VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP); |
| vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); |
| |
| err = insert_vm_struct(mm, vma); |
| if (err) |
| goto err; |
| |
| mm->stack_vm = mm->total_vm = 1; |
| mmap_write_unlock(mm); |
| bprm->p = vma->vm_end - sizeof(void *); |
| return 0; |
| err: |
| mmap_write_unlock(mm); |
| err_free: |
| bprm->vma = NULL; |
| vm_area_free(vma); |
| return err; |
| } |
| |
| static bool valid_arg_len(struct linux_binprm *bprm, long len) |
| { |
| return len <= MAX_ARG_STRLEN; |
| } |
| |
| #else |
| |
| static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages) |
| { |
| } |
| |
| static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, |
| int write) |
| { |
| struct page *page; |
| |
| page = bprm->page[pos / PAGE_SIZE]; |
| if (!page && write) { |
| page = alloc_page(GFP_HIGHUSER|__GFP_ZERO); |
| if (!page) |
| return NULL; |
| bprm->page[pos / PAGE_SIZE] = page; |
| } |
| |
| return page; |
| } |
| |
| static void put_arg_page(struct page *page) |
| { |
| } |
| |
| static void free_arg_page(struct linux_binprm *bprm, int i) |
| { |
| if (bprm->page[i]) { |
| __free_page(bprm->page[i]); |
| bprm->page[i] = NULL; |
| } |
| } |
| |
| static void free_arg_pages(struct linux_binprm *bprm) |
| { |
| int i; |
| |
| for (i = 0; i < MAX_ARG_PAGES; i++) |
| free_arg_page(bprm, i); |
| } |
| |
| static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, |
| struct page *page) |
| { |
| } |
| |
| static int __bprm_mm_init(struct linux_binprm *bprm) |
| { |
| bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *); |
| return 0; |
| } |
| |
| static bool valid_arg_len(struct linux_binprm *bprm, long len) |
| { |
| return len <= bprm->p; |
| } |
| |
| #endif /* CONFIG_MMU */ |
| |
| /* |
| * Create a new mm_struct and populate it with a temporary stack |
| * vm_area_struct. We don't have enough context at this point to set the stack |
| * flags, permissions, and offset, so we use temporary values. We'll update |
| * them later in setup_arg_pages(). |
| */ |
| static int bprm_mm_init(struct linux_binprm *bprm) |
| { |
| int err; |
| struct mm_struct *mm = NULL; |
| |
| bprm->mm = mm = mm_alloc(); |
| err = -ENOMEM; |
| if (!mm) |
| goto err; |
| |
| /* Save current stack limit for all calculations made during exec. */ |
| task_lock(current->group_leader); |
| bprm->rlim_stack = current->signal->rlim[RLIMIT_STACK]; |
| task_unlock(current->group_leader); |
| |
| err = __bprm_mm_init(bprm); |
| if (err) |
| goto err; |
| |
| return 0; |
| |
| err: |
| if (mm) { |
| bprm->mm = NULL; |
| mmdrop(mm); |
| } |
| |
| return err; |
| } |
| |
| struct user_arg_ptr { |
| #ifdef CONFIG_COMPAT |
| bool is_compat; |
| #endif |
| union { |
| const char __user *const __user *native; |
| #ifdef CONFIG_COMPAT |
| const compat_uptr_t __user *compat; |
| #endif |
| } ptr; |
| }; |
| |
| static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr) |
| { |
| const char __user *native; |
| |
| #ifdef CONFIG_COMPAT |
| if (unlikely(argv.is_compat)) { |
| compat_uptr_t compat; |
| |
| if (get_user(compat, argv.ptr.compat + nr)) |
| return ERR_PTR(-EFAULT); |
| |
| return compat_ptr(compat); |
| } |
| #endif |
| |
| if (get_user(native, argv.ptr.native + nr)) |
| return ERR_PTR(-EFAULT); |
| |
| return native; |
| } |
| |
| /* |
| * count() counts the number of strings in array ARGV. |
| */ |
| static int count(struct user_arg_ptr argv, int max) |
| { |
| int i = 0; |
| |
| if (argv.ptr.native != NULL) { |
| for (;;) { |
| const char __user *p = get_user_arg_ptr(argv, i); |
| |
| if (!p) |
| break; |
| |
| if (IS_ERR(p)) |
| return -EFAULT; |
| |
| if (i >= max) |
| return -E2BIG; |
| ++i; |
| |
| if (fatal_signal_pending(current)) |
| return -ERESTARTNOHAND; |
| cond_resched(); |
| } |
| } |
| return i; |
| } |
| |
| static int count_strings_kernel(const char *const *argv) |
| { |
| int i; |
| |
| if (!argv) |
| return 0; |
| |
| for (i = 0; argv[i]; ++i) { |
| if (i >= MAX_ARG_STRINGS) |
| return -E2BIG; |
| if (fatal_signal_pending(current)) |
| return -ERESTARTNOHAND; |
| cond_resched(); |
| } |
| return i; |
| } |
| |
| static int bprm_stack_limits(struct linux_binprm *bprm) |
| { |
| unsigned long limit, ptr_size; |
| |
| /* |
| * Limit to 1/4 of the max stack size or 3/4 of _STK_LIM |
| * (whichever is smaller) for the argv+env strings. |
| * This ensures that: |
| * - the remaining binfmt code will not run out of stack space, |
| * - the program will have a reasonable amount of stack left |
| * to work from. |
| */ |
| limit = _STK_LIM / 4 * 3; |
| limit = min(limit, bprm->rlim_stack.rlim_cur / 4); |
| /* |
| * We've historically supported up to 32 pages (ARG_MAX) |
| * of argument strings even with small stacks |
| */ |
| limit = max_t(unsigned long, limit, ARG_MAX); |
| /* |
| * We must account for the size of all the argv and envp pointers to |
| * the argv and envp strings, since they will also take up space in |
| * the stack. They aren't stored until much later when we can't |
| * signal to the parent that the child has run out of stack space. |
| * Instead, calculate it here so it's possible to fail gracefully. |
| * |
| * In the case of argc = 0, make sure there is space for adding a |
| * empty string (which will bump argc to 1), to ensure confused |
| * userspace programs don't start processing from argv[1], thinking |
| * argc can never be 0, to keep them from walking envp by accident. |
| * See do_execveat_common(). |
| */ |
| ptr_size = (max(bprm->argc, 1) + bprm->envc) * sizeof(void *); |
| if (limit <= ptr_size) |
| return -E2BIG; |
| limit -= ptr_size; |
| |
| bprm->argmin = bprm->p - limit; |
| return 0; |
| } |
| |
| /* |
| * 'copy_strings()' copies argument/environment strings from the old |
| * processes's memory to the new process's stack. The call to get_user_pages() |
| * ensures the destination page is created and not swapped out. |
| */ |
| static int copy_strings(int argc, struct user_arg_ptr argv, |
| struct linux_binprm *bprm) |
| { |
| struct page *kmapped_page = NULL; |
| char *kaddr = NULL; |
| unsigned long kpos = 0; |
| int ret; |
| |
| while (argc-- > 0) { |
| const char __user *str; |
| int len; |
| unsigned long pos; |
| |
| ret = -EFAULT; |
| str = get_user_arg_ptr(argv, argc); |
| if (IS_ERR(str)) |
| goto out; |
| |
| len = strnlen_user(str, MAX_ARG_STRLEN); |
| if (!len) |
| goto out; |
| |
| ret = -E2BIG; |
| if (!valid_arg_len(bprm, len)) |
| goto out; |
| |
| /* We're going to work our way backwards. */ |
| pos = bprm->p; |
| str += len; |
| bprm->p -= len; |
| #ifdef CONFIG_MMU |
| if (bprm->p < bprm->argmin) |
| goto out; |
| #endif |
| |
| while (len > 0) { |
| int offset, bytes_to_copy; |
| |
| if (fatal_signal_pending(current)) { |
| ret = -ERESTARTNOHAND; |
| goto out; |
| } |
| cond_resched(); |
| |
| offset = pos % PAGE_SIZE; |
| if (offset == 0) |
| offset = PAGE_SIZE; |
| |
| bytes_to_copy = offset; |
| if (bytes_to_copy > len) |
| bytes_to_copy = len; |
| |
| offset -= bytes_to_copy; |
| pos -= bytes_to_copy; |
| str -= bytes_to_copy; |
| len -= bytes_to_copy; |
| |
| if (!kmapped_page || kpos != (pos & PAGE_MASK)) { |
| struct page *page; |
| |
| page = get_arg_page(bprm, pos, 1); |
| if (!page) { |
| ret = -E2BIG; |
| goto out; |
| } |
| |
| if (kmapped_page) { |
| flush_dcache_page(kmapped_page); |
| kunmap_local(kaddr); |
| put_arg_page(kmapped_page); |
| } |
| kmapped_page = page; |
| kaddr = kmap_local_page(kmapped_page); |
| kpos = pos & PAGE_MASK; |
| flush_arg_page(bprm, kpos, kmapped_page); |
| } |
| if (copy_from_user(kaddr+offset, str, bytes_to_copy)) { |
| ret = -EFAULT; |
| goto out; |
| } |
| } |
| } |
| ret = 0; |
| out: |
| if (kmapped_page) { |
| flush_dcache_page(kmapped_page); |
| kunmap_local(kaddr); |
| put_arg_page(kmapped_page); |
| } |
| return ret; |
| } |
| |
| /* |
| * Copy and argument/environment string from the kernel to the processes stack. |
| */ |
| int copy_string_kernel(const char *arg, struct linux_binprm *bprm) |
| { |
| int len = strnlen(arg, MAX_ARG_STRLEN) + 1 /* terminating NUL */; |
| unsigned long pos = bprm->p; |
| |
| if (len == 0) |
| return -EFAULT; |
| if (!valid_arg_len(bprm, len)) |
| return -E2BIG; |
| |
| /* We're going to work our way backwards. */ |
| arg += len; |
| bprm->p -= len; |
| if (IS_ENABLED(CONFIG_MMU) && bprm->p < bprm->argmin) |
| return -E2BIG; |
| |
| while (len > 0) { |
| unsigned int bytes_to_copy = min_t(unsigned int, len, |
| min_not_zero(offset_in_page(pos), PAGE_SIZE)); |
| struct page *page; |
| |
| pos -= bytes_to_copy; |
| arg -= bytes_to_copy; |
| len -= bytes_to_copy; |
| |
| page = get_arg_page(bprm, pos, 1); |
| if (!page) |
| return -E2BIG; |
| flush_arg_page(bprm, pos & PAGE_MASK, page); |
| memcpy_to_page(page, offset_in_page(pos), arg, bytes_to_copy); |
| put_arg_page(page); |
| } |
| |
| return 0; |
| } |
| EXPORT_SYMBOL(copy_string_kernel); |
| |
| static int copy_strings_kernel(int argc, const char *const *argv, |
| struct linux_binprm *bprm) |
| { |
| while (argc-- > 0) { |
| int ret = copy_string_kernel(argv[argc], bprm); |
| if (ret < 0) |
| return ret; |
| if (fatal_signal_pending(current)) |
| return -ERESTARTNOHAND; |
| cond_resched(); |
| } |
| return 0; |
| } |
| |
| #ifdef CONFIG_MMU |
| |
| /* |
| * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once |
| * the binfmt code determines where the new stack should reside, we shift it to |
| * its final location. The process proceeds as follows: |
| * |
| * 1) Use shift to calculate the new vma endpoints. |
| * 2) Extend vma to cover both the old and new ranges. This ensures the |
| * arguments passed to subsequent functions are consistent. |
| * 3) Move vma's page tables to the new range. |
| * 4) Free up any cleared pgd range. |
| * 5) Shrink the vma to cover only the new range. |
| */ |
| static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| unsigned long old_start = vma->vm_start; |
| unsigned long old_end = vma->vm_end; |
| unsigned long length = old_end - old_start; |
| unsigned long new_start = old_start - shift; |
| unsigned long new_end = old_end - shift; |
| VMA_ITERATOR(vmi, mm, new_start); |
| struct vm_area_struct *next; |
| struct mmu_gather tlb; |
| |
| BUG_ON(new_start > new_end); |
| |
| /* |
| * ensure there are no vmas between where we want to go |
| * and where we are |
| */ |
| if (vma != vma_next(&vmi)) |
| return -EFAULT; |
| |
| /* |
| * cover the whole range: [new_start, old_end) |
| */ |
| if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL)) |
| return -ENOMEM; |
| |
| /* |
| * move the page tables downwards, on failure we rely on |
| * process cleanup to remove whatever mess we made. |
| */ |
| if (length != move_page_tables(vma, old_start, |
| vma, new_start, length, false)) |
| return -ENOMEM; |
| |
| lru_add_drain(); |
| tlb_gather_mmu(&tlb, mm); |
| next = vma_next(&vmi); |
| if (new_end > old_start) { |
| /* |
| * when the old and new regions overlap clear from new_end. |
| */ |
| free_pgd_range(&tlb, new_end, old_end, new_end, |
| next ? next->vm_start : USER_PGTABLES_CEILING); |
| } else { |
| /* |
| * otherwise, clean from old_start; this is done to not touch |
| * the address space in [new_end, old_start) some architectures |
| * have constraints on va-space that make this illegal (IA64) - |
| * for the others its just a little faster. |
| */ |
| free_pgd_range(&tlb, old_start, old_end, new_end, |
| next ? next->vm_start : USER_PGTABLES_CEILING); |
| } |
| tlb_finish_mmu(&tlb); |
| |
| /* |
| * Shrink the vma to just the new range. Always succeeds. |
| */ |
| vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL); |
| |
| return 0; |
| } |
| |
| /* |
| * Finalizes the stack vm_area_struct. The flags and permissions are updated, |
| * the stack is optionally relocated, and some extra space is added. |
| */ |
| int setup_arg_pages(struct linux_binprm *bprm, |
| unsigned long stack_top, |
| int executable_stack) |
| { |
| unsigned long ret; |
| unsigned long stack_shift; |
| struct mm_struct *mm = current->mm; |
| struct vm_area_struct *vma = bprm->vma; |
| struct vm_area_struct *prev = NULL; |
| unsigned long vm_flags; |
| unsigned long stack_base; |
| unsigned long stack_size; |
| unsigned long stack_expand; |
| unsigned long rlim_stack; |
| struct mmu_gather tlb; |
| |
| #ifdef CONFIG_STACK_GROWSUP |
| /* Limit stack size */ |
| stack_base = bprm->rlim_stack.rlim_max; |
| |
| stack_base = calc_max_stack_size(stack_base); |
| |
| /* Add space for stack randomization. */ |
| stack_base += (STACK_RND_MASK << PAGE_SHIFT); |
| |
| /* Make sure we didn't let the argument array grow too large. */ |
| if (vma->vm_end - vma->vm_start > stack_base) |
| return -ENOMEM; |
| |
| stack_base = PAGE_ALIGN(stack_top - stack_base); |
| |
| stack_shift = vma->vm_start - stack_base; |
| mm->arg_start = bprm->p - stack_shift; |
| bprm->p = vma->vm_end - stack_shift; |
| #else |
| stack_top = arch_align_stack(stack_top); |
| stack_top = PAGE_ALIGN(stack_top); |
| |
| if (unlikely(stack_top < mmap_min_addr) || |
| unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr)) |
| return -ENOMEM; |
| |
| stack_shift = vma->vm_end - stack_top; |
| |
| bprm->p -= stack_shift; |
| mm->arg_start = bprm->p; |
| #endif |
| |
| if (bprm->loader) |
| bprm->loader -= stack_shift; |
| bprm->exec -= stack_shift; |
| |
| if (mmap_write_lock_killable(mm)) |
| return -EINTR; |
| |
| vm_flags = VM_STACK_FLAGS; |
| |
| /* |
| * Adjust stack execute permissions; explicitly enable for |
| * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone |
| * (arch default) otherwise. |
| */ |
| if (unlikely(executable_stack == EXSTACK_ENABLE_X)) |
| vm_flags |= VM_EXEC; |
| else if (executable_stack == EXSTACK_DISABLE_X) |
| vm_flags &= ~VM_EXEC; |
| vm_flags |= mm->def_flags; |
| vm_flags |= VM_STACK_INCOMPLETE_SETUP; |
| |
| tlb_gather_mmu(&tlb, mm); |
| ret = mprotect_fixup(&tlb, vma, &prev, vma->vm_start, vma->vm_end, |
| vm_flags); |
| tlb_finish_mmu(&tlb); |
| |
| if (ret) |
| goto out_unlock; |
| BUG_ON(prev != vma); |
| |
| if (unlikely(vm_flags & VM_EXEC)) { |
| pr_warn_once("process '%pD4' started with executable stack\n", |
| bprm->file); |
| } |
| |
| /* Move stack pages down in memory. */ |
| if (stack_shift) { |
| ret = shift_arg_pages(vma, stack_shift); |
| if (ret) |
| goto out_unlock; |
| } |
| |
| /* mprotect_fixup is overkill to remove the temporary stack flags */ |
| vm_flags_clear(vma, VM_STACK_INCOMPLETE_SETUP); |
| |
| stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */ |
| stack_size = vma->vm_end - vma->vm_start; |
| /* |
| * Align this down to a page boundary as expand_stack |
| * will align it up. |
| */ |
| rlim_stack = bprm->rlim_stack.rlim_cur & PAGE_MASK; |
| #ifdef CONFIG_STACK_GROWSUP |
| if (stack_size + stack_expand > rlim_stack) |
| stack_base = vma->vm_start + rlim_stack; |
| else |
| stack_base = vma->vm_end + stack_expand; |
| #else |
| if (stack_size + stack_expand > rlim_stack) |
| stack_base = vma->vm_end - rlim_stack; |
| else |
| stack_base = vma->vm_start - stack_expand; |
| #endif |
| current->mm->start_stack = bprm->p; |
| ret = expand_stack_locked(vma, stack_base); |
| if (ret) |
| ret = -EFAULT; |
| |
| out_unlock: |
| mmap_write_unlock(mm); |
| return ret; |
| } |
| EXPORT_SYMBOL(setup_arg_pages); |
| |
| #else |
| |
| /* |
| * Transfer the program arguments and environment from the holding pages |
| * onto the stack. The provided stack pointer is adjusted accordingly. |
| */ |
| int transfer_args_to_stack(struct linux_binprm *bprm, |
| unsigned long *sp_location) |
| { |
| unsigned long index, stop, sp; |
| int ret = 0; |
| |
| stop = bprm->p >> PAGE_SHIFT; |
| sp = *sp_location; |
| |
| for (index = MAX_ARG_PAGES - 1; index >= stop; index--) { |
| unsigned int offset = index == stop ? bprm->p & ~PAGE_MASK : 0; |
| char *src = kmap_local_page(bprm->page[index]) + offset; |
| sp -= PAGE_SIZE - offset; |
| if (copy_to_user((void *) sp, src, PAGE_SIZE - offset) != 0) |
| ret = -EFAULT; |
| kunmap_local(src); |
| if (ret) |
| goto out; |
| } |
| |
| *sp_location = sp; |
| |
| out: |
| return ret; |
| } |
| EXPORT_SYMBOL(transfer_args_to_stack); |
| |
| #endif /* CONFIG_MMU */ |
| |
| static struct file *do_open_execat(int fd, struct filename *name, int flags) |
| { |
| struct file *file; |
| int err; |
| struct open_flags open_exec_flags = { |
| .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC, |
| .acc_mode = MAY_EXEC, |
| .intent = LOOKUP_OPEN, |
| .lookup_flags = LOOKUP_FOLLOW, |
| }; |
| |
| if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0) |
| return ERR_PTR(-EINVAL); |
| if (flags & AT_SYMLINK_NOFOLLOW) |
| open_exec_flags.lookup_flags &= ~LOOKUP_FOLLOW; |
| if (flags & AT_EMPTY_PATH) |
| open_exec_flags.lookup_flags |= LOOKUP_EMPTY; |
| |
| file = do_filp_open(fd, name, &open_exec_flags); |
| if (IS_ERR(file)) |
| goto out; |
| |
| /* |
| * may_open() has already checked for this, so it should be |
| * impossible to trip now. But we need to be extra cautious |
| * and check again at the very end too. |
| */ |
| err = -EACCES; |
| if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) || |
| path_noexec(&file->f_path))) |
| goto exit; |
| |
| err = deny_write_access(file); |
| if (err) |
| goto exit; |
| |
| if (name->name[0] != '\0') |
| fsnotify_open(file); |
| |
| out: |
| return file; |
| |
| exit: |
| fput(file); |
| return ERR_PTR(err); |
| } |
| |
| struct file *open_exec(const char *name) |
| { |
| struct filename *filename = getname_kernel(name); |
| struct file *f = ERR_CAST(filename); |
| |
| if (!IS_ERR(filename)) { |
| f = do_open_execat(AT_FDCWD, filename, 0); |
| putname(filename); |
| } |
| return f; |
| } |
| EXPORT_SYMBOL(open_exec); |
| |
| #if defined(CONFIG_BINFMT_FLAT) || defined(CONFIG_BINFMT_ELF_FDPIC) |
| ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len) |
| { |
| ssize_t res = vfs_read(file, (void __user *)addr, len, &pos); |
| if (res > 0) |
| flush_icache_user_range(addr, addr + len); |
| return res; |
| } |
| EXPORT_SYMBOL(read_code); |
| #endif |
| |
| /* |
| * Maps the mm_struct mm into the current task struct. |
| * On success, this function returns with exec_update_lock |
| * held for writing. |
| */ |
| static int exec_mmap(struct mm_struct *mm) |
| { |
| struct task_struct *tsk; |
| struct mm_struct *old_mm, *active_mm; |
| int ret; |
| |
| /* Notify parent that we're no longer interested in the old VM */ |
| tsk = current; |
| old_mm = current->mm; |
| exec_mm_release(tsk, old_mm); |
| if (old_mm) |
| sync_mm_rss(old_mm); |
| |
| ret = down_write_killable(&tsk->signal->exec_update_lock); |
| if (ret) |
| return ret; |
| |
| if (old_mm) { |
| /* |
| * If there is a pending fatal signal perhaps a signal |
| * whose default action is to create a coredump get |
| * out and die instead of going through with the exec. |
| */ |
| ret = mmap_read_lock_killable(old_mm); |
| if (ret) { |
| up_write(&tsk->signal->exec_update_lock); |
| return ret; |
| } |
| } |
| |
| task_lock(tsk); |
| membarrier_exec_mmap(mm); |
| |
| local_irq_disable(); |
| active_mm = tsk->active_mm; |
| tsk->active_mm = mm; |
| tsk->mm = mm; |
| /* |
| * This prevents preemption while active_mm is being loaded and |
| * it and mm are being updated, which could cause problems for |
| * lazy tlb mm refcounting when these are updated by context |
| * switches. Not all architectures can handle irqs off over |
| * activate_mm yet. |
| */ |
| if (!IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM)) |
| local_irq_enable(); |
| activate_mm(active_mm, mm); |
| if (IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM)) |
| local_irq_enable(); |
| lru_gen_add_mm(mm); |
| task_unlock(tsk); |
| lru_gen_use_mm(mm); |
| if (old_mm) { |
| mmap_read_unlock(old_mm); |
| BUG_ON(active_mm != old_mm); |
| setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm); |
| mm_update_next_owner(old_mm); |
| mmput(old_mm); |
| return 0; |
| } |
| mmdrop(active_mm); |
| return 0; |
| } |
| |
| static int de_thread(struct task_struct *tsk) |
| { |
| struct signal_struct *sig = tsk->signal; |
| struct sighand_struct *oldsighand = tsk->sighand; |
| spinlock_t *lock = &oldsighand->siglock; |
| |
| if (thread_group_empty(tsk)) |
| goto no_thread_group; |
| |
| /* |
| * Kill all other threads in the thread group. |
| */ |
| spin_lock_irq(lock); |
| if ((sig->flags & SIGNAL_GROUP_EXIT) || sig->group_exec_task) { |
| /* |
| * Another group action in progress, just |
| * return so that the signal is processed. |
| */ |
| spin_unlock_irq(lock); |
| return -EAGAIN; |
| } |
| |
| sig->group_exec_task = tsk; |
| sig->notify_count = zap_other_threads(tsk); |
| if (!thread_group_leader(tsk)) |
| sig->notify_count--; |
| |
| while (sig->notify_count) { |
| __set_current_state(TASK_KILLABLE); |
| spin_unlock_irq(lock); |
| schedule(); |
| if (__fatal_signal_pending(tsk)) |
| goto killed; |
| spin_lock_irq(lock); |
| } |
| spin_unlock_irq(lock); |
| |
| /* |
| * At this point all other threads have exited, all we have to |
| * do is to wait for the thread group leader to become inactive, |
| * and to assume its PID: |
| */ |
| if (!thread_group_leader(tsk)) { |
| struct task_struct *leader = tsk->group_leader; |
| |
| for (;;) { |
| cgroup_threadgroup_change_begin(tsk); |
| write_lock_irq(&tasklist_lock); |
| /* |
| * Do this under tasklist_lock to ensure that |
| * exit_notify() can't miss ->group_exec_task |
| */ |
| sig->notify_count = -1; |
| if (likely(leader->exit_state)) |
| break; |
| __set_current_state(TASK_KILLABLE); |
| write_unlock_irq(&tasklist_lock); |
| cgroup_threadgroup_change_end(tsk); |
| schedule(); |
| if (__fatal_signal_pending(tsk)) |
| goto killed; |
| } |
| |
| /* |
| * The only record we have of the real-time age of a |
| * process, regardless of execs it's done, is start_time. |
| * All the past CPU time is accumulated in signal_struct |
| * from sister threads now dead. But in this non-leader |
| * exec, nothing survives from the original leader thread, |
| * whose birth marks the true age of this process now. |
| * When we take on its identity by switching to its PID, we |
| * also take its birthdate (always earlier than our own). |
| */ |
| tsk->start_time = leader->start_time; |
| tsk->start_boottime = leader->start_boottime; |
| |
| BUG_ON(!same_thread_group(leader, tsk)); |
| /* |
| * An exec() starts a new thread group with the |
| * TGID of the previous thread group. Rehash the |
| * two threads with a switched PID, and release |
| * the former thread group leader: |
| */ |
| |
| /* Become a process group leader with the old leader's pid. |
| * The old leader becomes a thread of the this thread group. |
| */ |
| exchange_tids(tsk, leader); |
| transfer_pid(leader, tsk, PIDTYPE_TGID); |
| transfer_pid(leader, tsk, PIDTYPE_PGID); |
| transfer_pid(leader, tsk, PIDTYPE_SID); |
| |
| list_replace_rcu(&leader->tasks, &tsk->tasks); |
| list_replace_init(&leader->sibling, &tsk->sibling); |
| |
| tsk->group_leader = tsk; |
| leader->group_leader = tsk; |
| |
| tsk->exit_signal = SIGCHLD; |
| leader->exit_signal = -1; |
| |
| BUG_ON(leader->exit_state != EXIT_ZOMBIE); |
| leader->exit_state = EXIT_DEAD; |
| |
| /* |
| * We are going to release_task()->ptrace_unlink() silently, |
| * the tracer can sleep in do_wait(). EXIT_DEAD guarantees |
| * the tracer won't block again waiting for this thread. |
| */ |
| if (unlikely(leader->ptrace)) |
| __wake_up_parent(leader, leader->parent); |
| write_unlock_irq(&tasklist_lock); |
| cgroup_threadgroup_change_end(tsk); |
| |
| release_task(leader); |
| } |
| |
| sig->group_exec_task = NULL; |
| sig->notify_count = 0; |
| |
| no_thread_group: |
| /* we have changed execution domain */ |
| tsk->exit_signal = SIGCHLD; |
| |
| BUG_ON(!thread_group_leader(tsk)); |
| return 0; |
| |
| killed: |
| /* protects against exit_notify() and __exit_signal() */ |
| read_lock(&tasklist_lock); |
| sig->group_exec_task = NULL; |
| sig->notify_count = 0; |
| read_unlock(&tasklist_lock); |
| return -EAGAIN; |
| } |
| |
| |
| /* |
| * This function makes sure the current process has its own signal table, |
| * so that flush_signal_handlers can later reset the handlers without |
| * disturbing other processes. (Other processes might share the signal |
| * table via the CLONE_SIGHAND option to clone().) |
| */ |
| static int unshare_sighand(struct task_struct *me) |
| { |
| struct sighand_struct *oldsighand = me->sighand; |
| |
| if (refcount_read(&oldsighand->count) != 1) { |
| struct sighand_struct *newsighand; |
| /* |
| * This ->sighand is shared with the CLONE_SIGHAND |
| * but not CLONE_THREAD task, switch to the new one. |
| */ |
| newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); |
| if (!newsighand) |
| return -ENOMEM; |
| |
| refcount_set(&newsighand->count, 1); |
| |
| write_lock_irq(&tasklist_lock); |
| spin_lock(&oldsighand->siglock); |
| memcpy(newsighand->action, oldsighand->action, |
| sizeof(newsighand->action)); |
| rcu_assign_pointer(me->sighand, newsighand); |
| spin_unlock(&oldsighand->siglock); |
| write_unlock_irq(&tasklist_lock); |
| |
| __cleanup_sighand(oldsighand); |
| } |
| return 0; |
| } |
| |
| char *__get_task_comm(char *buf, size_t buf_size, struct task_struct *tsk) |
| { |
| task_lock(tsk); |
| /* Always NUL terminated and zero-padded */ |
| strscpy_pad(buf, tsk->comm, buf_size); |
| task_unlock(tsk); |
| return buf; |
| } |
| EXPORT_SYMBOL_GPL(__get_task_comm); |
| |
| /* |
| * These functions flushes out all traces of the currently running executable |
| * so that a new one can be started |
| */ |
| |
| void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec) |
| { |
| task_lock(tsk); |
| trace_task_rename(tsk, buf); |
| strscpy_pad(tsk->comm, buf, sizeof(tsk->comm)); |
| task_unlock(tsk); |
| perf_event_comm(tsk, exec); |
| } |
| |
| /* |
| * Calling this is the point of no return. None of the failures will be |
| * seen by userspace since either the process is already taking a fatal |
| * signal (via de_thread() or coredump), or will have SEGV raised |
| * (after exec_mmap()) by search_binary_handler (see below). |
| */ |
| int begin_new_exec(struct linux_binprm * bprm) |
| { |
| struct task_struct *me = current; |
| int retval; |
| |
| /* Once we are committed compute the creds */ |
| retval = bprm_creds_from_file(bprm); |
| if (retval) |
| return retval; |
| |
| /* |
| * Ensure all future errors are fatal. |
| */ |
| bprm->point_of_no_return = true; |
| |
| /* |
| * Make this the only thread in the thread group. |
| */ |
| retval = de_thread(me); |
| if (retval) |
| goto out; |
| |
| /* |
| * Cancel any io_uring activity across execve |
| */ |
| io_uring_task_cancel(); |
| |
| /* Ensure the files table is not shared. */ |
| retval = unshare_files(); |
| if (retval) |
| goto out; |
| |
| /* |
| * Must be called _before_ exec_mmap() as bprm->mm is |
| * not visible until then. This also enables the update |
| * to be lockless. |
| */ |
| retval = set_mm_exe_file(bprm->mm, bprm->file); |
| if (retval) |
| goto out; |
| |
| /* If the binary is not readable then enforce mm->dumpable=0 */ |
| would_dump(bprm, bprm->file); |
| if (bprm->have_execfd) |
| would_dump(bprm, bprm->executable); |
| |
| /* |
| * Release all of the old mmap stuff |
| */ |
| acct_arg_size(bprm, 0); |
| retval = exec_mmap(bprm->mm); |
| if (retval) |
| goto out; |
| |
| bprm->mm = NULL; |
| |
| #ifdef CONFIG_POSIX_TIMERS |
| spin_lock_irq(&me->sighand->siglock); |
| posix_cpu_timers_exit(me); |
| spin_unlock_irq(&me->sighand->siglock); |
| exit_itimers(me); |
| flush_itimer_signals(); |
| #endif |
| |
| /* |
| * Make the signal table private. |
| */ |
| retval = unshare_sighand(me); |
| if (retval) |
| goto out_unlock; |
| |
| me->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | |
| PF_NOFREEZE | PF_NO_SETAFFINITY); |
| flush_thread(); |
| me->personality &= ~bprm->per_clear; |
| |
| clear_syscall_work_syscall_user_dispatch(me); |
| |
| /* |
| * We have to apply CLOEXEC before we change whether the process is |
| * dumpable (in setup_new_exec) to avoid a race with a process in userspace |
| * trying to access the should-be-closed file descriptors of a process |
| * undergoing exec(2). |
| */ |
| do_close_on_exec(me->files); |
| |
| if (bprm->secureexec) { |
| /* Make sure parent cannot signal privileged process. */ |
| me->pdeath_signal = 0; |
| |
| /* |
| * For secureexec, reset the stack limit to sane default to |
| * avoid bad behavior from the prior rlimits. This has to |
| * happen before arch_pick_mmap_layout(), which examines |
| * RLIMIT_STACK, but after the point of no return to avoid |
| * needing to clean up the change on failure. |
| */ |
| if (bprm->rlim_stack.rlim_cur > _STK_LIM) |
| bprm->rlim_stack.rlim_cur = _STK_LIM; |
| } |
| |
| me->sas_ss_sp = me->sas_ss_size = 0; |
| |
| /* |
| * Figure out dumpability. Note that this checking only of current |
| * is wrong, but userspace depends on it. This should be testing |
| * bprm->secureexec instead. |
| */ |
| if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP || |
| !(uid_eq(current_euid(), current_uid()) && |
| gid_eq(current_egid(), current_gid()))) |
| set_dumpable(current->mm, suid_dumpable); |
| else |
| set_dumpable(current->mm, SUID_DUMP_USER); |
| |
| perf_event_exec(); |
| __set_task_comm(me, kbasename(bprm->filename), true); |
| |
| /* An exec changes our domain. We are no longer part of the thread |
| group */ |
| WRITE_ONCE(me->self_exec_id, me->self_exec_id + 1); |
| flush_signal_handlers(me, 0); |
| |
| retval = set_cred_ucounts(bprm->cred); |
| if (retval < 0) |
| goto out_unlock; |
| |
| /* |
| * install the new credentials for this executable |
| */ |
| security_bprm_committing_creds(bprm); |
| |
| commit_creds(bprm->cred); |
| bprm->cred = NULL; |
| |
| /* |
| * Disable monitoring for regular users |
| * when executing setuid binaries. Must |
| * wait until new credentials are committed |
| * by commit_creds() above |
| */ |
| if (get_dumpable(me->mm) != SUID_DUMP_USER) |
| perf_event_exit_task(me); |
| /* |
| * cred_guard_mutex must be held at least to this point to prevent |
| * ptrace_attach() from altering our determination of the task's |
| * credentials; any time after this it may be unlocked. |
| */ |
| security_bprm_committed_creds(bprm); |
| |
| /* Pass the opened binary to the interpreter. */ |
| if (bprm->have_execfd) { |
| retval = get_unused_fd_flags(0); |
| if (retval < 0) |
| goto out_unlock; |
| fd_install(retval, bprm->executable); |
| bprm->executable = NULL; |
| bprm->execfd = retval; |
| } |
| return 0; |
| |
| out_unlock: |
| up_write(&me->signal->exec_update_lock); |
| out: |
| return retval; |
| } |
| EXPORT_SYMBOL(begin_new_exec); |
| |
| void would_dump(struct linux_binprm *bprm, struct file *file) |
| { |
| struct inode *inode = file_inode(file); |
| struct user_namespace *mnt_userns = file_mnt_user_ns(file); |
| if (inode_permission(mnt_userns, inode, MAY_READ) < 0) { |
| struct user_namespace *old, *user_ns; |
| bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP; |
| |
| /* Ensure mm->user_ns contains the executable */ |
| user_ns = old = bprm->mm->user_ns; |
| while ((user_ns != &init_user_ns) && |
| !privileged_wrt_inode_uidgid(user_ns, mnt_userns, inode)) |
| user_ns = user_ns->parent; |
| |
| if (old != user_ns) { |
| bprm->mm->user_ns = get_user_ns(user_ns); |
| put_user_ns(old); |
| } |
| } |
| } |
| EXPORT_SYMBOL(would_dump); |
| |
| void setup_new_exec(struct linux_binprm * bprm) |
| { |
| /* Setup things that can depend upon the personality */ |
| struct task_struct *me = current; |
| |
| arch_pick_mmap_layout(me->mm, &bprm->rlim_stack); |
| |
| arch_setup_new_exec(); |
| |
| /* Set the new mm task size. We have to do that late because it may |
| * depend on TIF_32BIT which is only updated in flush_thread() on |
| * some architectures like powerpc |
| */ |
| me->mm->task_size = TASK_SIZE; |
| up_write(&me->signal->exec_update_lock); |
| mutex_unlock(&me->signal->cred_guard_mutex); |
| } |
| EXPORT_SYMBOL(setup_new_exec); |
| |
| /* Runs immediately before start_thread() takes over. */ |
| void finalize_exec(struct linux_binprm *bprm) |
| { |
| /* Store any stack rlimit changes before starting thread. */ |
| task_lock(current->group_leader); |
| current->signal->rlim[RLIMIT_STACK] = bprm->rlim_stack; |
| task_unlock(current->group_leader); |
| } |
| EXPORT_SYMBOL(finalize_exec); |
| |
| /* |
| * Prepare credentials and lock ->cred_guard_mutex. |
| * setup_new_exec() commits the new creds and drops the lock. |
| * Or, if exec fails before, free_bprm() should release ->cred |
| * and unlock. |
| */ |
| static int prepare_bprm_creds(struct linux_binprm *bprm) |
| { |
| if (mutex_lock_interruptible(¤t->signal->cred_guard_mutex)) |
| return -ERESTARTNOINTR; |
| |
| bprm->cred = prepare_exec_creds(); |
| if (likely(bprm->cred)) |
| return 0; |
| |
| mutex_unlock(¤t->signal->cred_guard_mutex); |
| return -ENOMEM; |
| } |
| |
| static void free_bprm(struct linux_binprm *bprm) |
| { |
| if (bprm->mm) { |
| acct_arg_size(bprm, 0); |
| mmput(bprm->mm); |
| } |
| free_arg_pages(bprm); |
| if (bprm->cred) { |
| mutex_unlock(¤t->signal->cred_guard_mutex); |
| abort_creds(bprm->cred); |
| } |
| if (bprm->file) { |
| allow_write_access(bprm->file); |
| fput(bprm->file); |
| } |
| if (bprm->executable) |
| fput(bprm->executable); |
| /* If a binfmt changed the interp, free it. */ |
| if (bprm->interp != bprm->filename) |
| kfree(bprm->interp); |
| kfree(bprm->fdpath); |
| kfree(bprm); |
| } |
| |
| static struct linux_binprm *alloc_bprm(int fd, struct filename *filename) |
| { |
| struct linux_binprm *bprm = kzalloc(sizeof(*bprm), GFP_KERNEL); |
| int retval = -ENOMEM; |
| if (!bprm) |
| goto out; |
| |
| if (fd == AT_FDCWD || filename->name[0] == '/') { |
| bprm->filename = filename->name; |
| } else { |
| if (filename->name[0] == '\0') |
| bprm->fdpath = kasprintf(GFP_KERNEL, "/dev/fd/%d", fd); |
| else |
| bprm->fdpath = kasprintf(GFP_KERNEL, "/dev/fd/%d/%s", |
| fd, filename->name); |
| if (!bprm->fdpath) |
| goto out_free; |
| |
| bprm->filename = bprm->fdpath; |
| } |
| bprm->interp = bprm->filename; |
| |
| retval = bprm_mm_init(bprm); |
| if (retval) |
| goto out_free; |
| return bprm; |
| |
| out_free: |
| free_bprm(bprm); |
| out: |
| return ERR_PTR(retval); |
| } |
| |
| int bprm_change_interp(const char *interp, struct linux_binprm *bprm) |
| { |
| /* If a binfmt changed the interp, free it first. */ |
| if (bprm->interp != bprm->filename) |
| kfree(bprm->interp); |
| bprm->interp = kstrdup(interp, GFP_KERNEL); |
| if (!bprm->interp) |
| return -ENOMEM; |
| return 0; |
| } |
| EXPORT_SYMBOL(bprm_change_interp); |
| |
| /* |
| * determine how safe it is to execute the proposed program |
| * - the caller must hold ->cred_guard_mutex to protect against |
| * PTRACE_ATTACH or seccomp thread-sync |
| */ |
| static void check_unsafe_exec(struct linux_binprm *bprm) |
| { |
| struct task_struct *p = current, *t; |
| unsigned n_fs; |
| |
| if (p->ptrace) |
| bprm->unsafe |= LSM_UNSAFE_PTRACE; |
| |
| /* |
| * This isn't strictly necessary, but it makes it harder for LSMs to |
| * mess up. |
| */ |
| if (task_no_new_privs(current)) |
| bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS; |
| |
| t = p; |
| n_fs = 1; |
| spin_lock(&p->fs->lock); |
| rcu_read_lock(); |
| while_each_thread(p, t) { |
| if (t->fs == p->fs) |
| n_fs++; |
| } |
| rcu_read_unlock(); |
| |
| if (p->fs->users > n_fs) |
| bprm->unsafe |= LSM_UNSAFE_SHARE; |
| else |
| p->fs->in_exec = 1; |
| spin_unlock(&p->fs->lock); |
| } |
| |
| static void bprm_fill_uid(struct linux_binprm *bprm, struct file *file) |
| { |
| /* Handle suid and sgid on files */ |
| struct user_namespace *mnt_userns; |
| struct inode *inode = file_inode(file); |
| unsigned int mode; |
| kuid_t uid; |
| kgid_t gid; |
| |
| if (!mnt_may_suid(file->f_path.mnt)) |
| return; |
| |
| if (task_no_new_privs(current)) |
| return; |
| |
| mode = READ_ONCE(inode->i_mode); |
| if (!(mode & (S_ISUID|S_ISGID))) |
| return; |
| |
| mnt_userns = file_mnt_user_ns(file); |
| |
| /* Be careful if suid/sgid is set */ |
| inode_lock(inode); |
| |
| /* reload atomically mode/uid/gid now that lock held */ |
| mode = inode->i_mode; |
| uid = i_uid_into_mnt(mnt_userns, inode); |
| gid = i_gid_into_mnt(mnt_userns, inode); |
| inode_unlock(inode); |
| |
| /* We ignore suid/sgid if there are no mappings for them in the ns */ |
| if (!kuid_has_mapping(bprm->cred->user_ns, uid) || |
| !kgid_has_mapping(bprm->cred->user_ns, gid)) |
| return; |
| |
| if (mode & S_ISUID) { |
| bprm->per_clear |= PER_CLEAR_ON_SETID; |
| bprm->cred->euid = uid; |
| } |
| |
| if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { |
| bprm->per_clear |= PER_CLEAR_ON_SETID; |
| bprm->cred->egid = gid; |
| } |
| } |
| |
| /* |
| * Compute brpm->cred based upon the final binary. |
| */ |
| static int bprm_creds_from_file(struct linux_binprm *bprm) |
| { |
| /* Compute creds based on which file? */ |
| struct file *file = bprm->execfd_creds ? bprm->executable : bprm->file; |
| |
| bprm_fill_uid(bprm, file); |
| return security_bprm_creds_from_file(bprm, file); |
| } |
| |
| /* |
| * Fill the binprm structure from the inode. |
| * Read the first BINPRM_BUF_SIZE bytes |
| * |
| * This may be called multiple times for binary chains (scripts for example). |
| */ |
| static int prepare_binprm(struct linux_binprm *bprm) |
| { |
| loff_t pos = 0; |
| |
| memset(bprm->buf, 0, BINPRM_BUF_SIZE); |
| return kernel_read(bprm->file, bprm->buf, BINPRM_BUF_SIZE, &pos); |
| } |
| |
| /* |
| * Arguments are '\0' separated strings found at the location bprm->p |
| * points to; chop off the first by relocating brpm->p to right after |
| * the first '\0' encountered. |
| */ |
| int remove_arg_zero(struct linux_binprm *bprm) |
| { |
| int ret = 0; |
| unsigned long offset; |
| char *kaddr; |
| struct page *page; |
| |
| if (!bprm->argc) |
| return 0; |
| |
| do { |
| offset = bprm->p & ~PAGE_MASK; |
| page = get_arg_page(bprm, bprm->p, 0); |
| if (!page) { |
| ret = -EFAULT; |
| goto out; |
| } |
| kaddr = kmap_local_page(page); |
| |
| for (; offset < PAGE_SIZE && kaddr[offset]; |
| offset++, bprm->p++) |
| ; |
| |
| kunmap_local(kaddr); |
| put_arg_page(page); |
| } while (offset == PAGE_SIZE); |
| |
| bprm->p++; |
| bprm->argc--; |
| ret = 0; |
| |
| out: |
| return ret; |
| } |
| EXPORT_SYMBOL(remove_arg_zero); |
| |
| #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e)) |
| /* |
| * cycle the list of binary formats handler, until one recognizes the image |
| */ |
| static int search_binary_handler(struct linux_binprm *bprm) |
| { |
| bool need_retry = IS_ENABLED(CONFIG_MODULES); |
| struct linux_binfmt *fmt; |
| int retval; |
| |
| retval = prepare_binprm(bprm); |
| if (retval < 0) |
| return retval; |
| |
| retval = security_bprm_check(bprm); |
| if (retval) |
| return retval; |
| |
| retval = -ENOENT; |
| retry: |
| read_lock(&binfmt_lock); |
| list_for_each_entry(fmt, &formats, lh) { |
| if (!try_module_get(fmt->module)) |
| continue; |
| read_unlock(&binfmt_lock); |
| |
| retval = fmt->load_binary(bprm); |
| |
| read_lock(&binfmt_lock); |
| put_binfmt(fmt); |
| if (bprm->point_of_no_return || (retval != -ENOEXEC)) { |
| read_unlock(&binfmt_lock); |
| return retval; |
| } |
| } |
| read_unlock(&binfmt_lock); |
| |
| if (need_retry) { |
| if (printable(bprm->buf[0]) && printable(bprm->buf[1]) && |
| printable(bprm->buf[2]) && printable(bprm->buf[3])) |
| return retval; |
| if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0) |
| return retval; |
| need_retry = false; |
| goto retry; |
| } |
| |
| return retval; |
| } |
| |
| static int exec_binprm(struct linux_binprm *bprm) |
| { |
| pid_t old_pid, old_vpid; |
| int ret, depth; |
| |
| /* Need to fetch pid before load_binary changes it */ |
| old_pid = current->pid; |
| rcu_read_lock(); |
| old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent)); |
| rcu_read_unlock(); |
| |
| /* This allows 4 levels of binfmt rewrites before failing hard. */ |
| for (depth = 0;; depth++) { |
| struct file *exec; |
| if (depth > 5) |
| return -ELOOP; |
| |
| ret = search_binary_handler(bprm); |
| if (ret < 0) |
| return ret; |
| if (!bprm->interpreter) |
| break; |
| |
| exec = bprm->file; |
| bprm->file = bprm->interpreter; |
| bprm->interpreter = NULL; |
| |
| allow_write_access(exec); |
| if (unlikely(bprm->have_execfd)) { |
| if (bprm->executable) { |
| fput(exec); |
| return -ENOEXEC; |
| } |
| bprm->executable = exec; |
| } else |
| fput(exec); |
| } |
| |
| audit_bprm(bprm); |
| trace_sched_process_exec(current, old_pid, bprm); |
| ptrace_event(PTRACE_EVENT_EXEC, old_vpid); |
| proc_exec_connector(current); |
| return 0; |
| } |
| |
| /* |
| * sys_execve() executes a new program. |
| */ |
| static int bprm_execve(struct linux_binprm *bprm, |
| int fd, struct filename *filename, int flags) |
| { |
| struct file *file; |
| int retval; |
| |
| retval = prepare_bprm_creds(bprm); |
| if (retval) |
| return retval; |
| |
| check_unsafe_exec(bprm); |
| current->in_execve = 1; |
| |
| file = do_open_execat(fd, filename, flags); |
| retval = PTR_ERR(file); |
| if (IS_ERR(file)) |
| goto out_unmark; |
| |
| sched_exec(); |
| |
| bprm->file = file; |
| /* |
| * Record that a name derived from an O_CLOEXEC fd will be |
| * inaccessible after exec. This allows the code in exec to |
| * choose to fail when the executable is not mmaped into the |
| * interpreter and an open file descriptor is not passed to |
| * the interpreter. This makes for a better user experience |
| * than having the interpreter start and then immediately fail |
| * when it finds the executable is inaccessible. |
| */ |
| if (bprm->fdpath && get_close_on_exec(fd)) |
| bprm->interp_flags |= BINPRM_FLAGS_PATH_INACCESSIBLE; |
| |
| /* Set the unchanging part of bprm->cred */ |
| retval = security_bprm_creds_for_exec(bprm); |
| if (retval) |
| goto out; |
| |
| retval = exec_binprm(bprm); |
| if (retval < 0) |
| goto out; |
| |
| /* execve succeeded */ |
| current->fs->in_exec = 0; |
| current->in_execve = 0; |
| rseq_execve(current); |
| acct_update_integrals(current); |
| task_numa_free(current, false); |
| return retval; |
| |
| out: |
| /* |
| * If past the point of no return ensure the code never |
| * returns to the userspace process. Use an existing fatal |
| * signal if present otherwise terminate the process with |
| * SIGSEGV. |
| */ |
| if (bprm->point_of_no_return && !fatal_signal_pending(current)) |
| force_fatal_sig(SIGSEGV); |
| |
| out_unmark: |
| current->fs->in_exec = 0; |
| current->in_execve = 0; |
| |
| return retval; |
| } |
| |
| static int do_execveat_common(int fd, struct filename *filename, |
| struct user_arg_ptr argv, |
| struct user_arg_ptr envp, |
| int flags) |
| { |
| struct linux_binprm *bprm; |
| int retval; |
| |
| if (IS_ERR(filename)) |
| return PTR_ERR(filename); |
| |
| /* |
| * We move the actual failure in case of RLIMIT_NPROC excess from |
| * set*uid() to execve() because too many poorly written programs |
| * don't check setuid() return code. Here we additionally recheck |
| * whether NPROC limit is still exceeded. |
| */ |
| if ((current->flags & PF_NPROC_EXCEEDED) && |
| is_rlimit_overlimit(current_ucounts(), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) { |
| retval = -EAGAIN; |
| goto out_ret; |
| } |
| |
| /* We're below the limit (still or again), so we don't want to make |
| * further execve() calls fail. */ |
| current->flags &= ~PF_NPROC_EXCEEDED; |
| |
| bprm = alloc_bprm(fd, filename); |
| if (IS_ERR(bprm)) { |
| retval = PTR_ERR(bprm); |
| goto out_ret; |
| } |
| |
| retval = count(argv, MAX_ARG_STRINGS); |
| if (retval == 0) |
| pr_warn_once("process '%s' launched '%s' with NULL argv: empty string added\n", |
| current->comm, bprm->filename); |
| if (retval < 0) |
| goto out_free; |
| bprm->argc = retval; |
| |
| retval = count(envp, MAX_ARG_STRINGS); |
| if (retval < 0) |
| goto out_free; |
| bprm->envc = retval; |
| |
| retval = bprm_stack_limits(bprm); |
| if (retval < 0) |
| goto out_free; |
| |
| retval = copy_string_kernel(bprm->filename, bprm); |
| if (retval < 0) |
| goto out_free; |
| bprm->exec = bprm->p; |
| |
| retval = copy_strings(bprm->envc, envp, bprm); |
| if (retval < 0) |
| goto out_free; |
| |
| retval = copy_strings(bprm->argc, argv, bprm); |
| if (retval < 0) |
| goto out_free; |
| |
| /* |
| * When argv is empty, add an empty string ("") as argv[0] to |
| * ensure confused userspace programs that start processing |
| * from argv[1] won't end up walking envp. See also |
| * bprm_stack_limits(). |
| */ |
| if (bprm->argc == 0) { |
| retval = copy_string_kernel("", bprm); |
| if (retval < 0) |
| goto out_free; |
| bprm->argc = 1; |
| } |
| |
| retval = bprm_execve(bprm, fd, filename, flags); |
| out_free: |
| free_bprm(bprm); |
| |
| out_ret: |
| putname(filename); |
| return retval; |
| } |
| |
| int kernel_execve(const char *kernel_filename, |
| const char *const *argv, const char *const *envp) |
| { |
| struct filename *filename; |
| struct linux_binprm *bprm; |
| int fd = AT_FDCWD; |
| int retval; |
| |
| /* It is non-sense for kernel threads to call execve */ |
| if (WARN_ON_ONCE(current->flags & PF_KTHREAD)) |
| return -EINVAL; |
| |
| filename = getname_kernel(kernel_filename); |
| if (IS_ERR(filename)) |
| return PTR_ERR(filename); |
| |
| bprm = alloc_bprm(fd, filename); |
| if (IS_ERR(bprm)) { |
| retval = PTR_ERR(bprm); |
| goto out_ret; |
| } |
| |
| retval = count_strings_kernel(argv); |
| if (WARN_ON_ONCE(retval == 0)) |
| retval = -EINVAL; |
| if (retval < 0) |
| goto out_free; |
| bprm->argc = retval; |
| |
| retval = count_strings_kernel(envp); |
| if (retval < 0) |
| goto out_free; |
| bprm->envc = retval; |
| |
| retval = bprm_stack_limits(bprm); |
| if (retval < 0) |
| goto out_free; |
| |
| retval = copy_string_kernel(bprm->filename, bprm); |
| if (retval < 0) |
| goto out_free; |
| bprm->exec = bprm->p; |
| |
| retval = copy_strings_kernel(bprm->envc, envp, bprm); |
| if (retval < 0) |
| goto out_free; |
| |
| retval = copy_strings_kernel(bprm->argc, argv, bprm); |
| if (retval < 0) |
| goto out_free; |
| |
| retval = bprm_execve(bprm, fd, filename, 0); |
| out_free: |
| free_bprm(bprm); |
| out_ret: |
| putname(filename); |
| return retval; |
| } |
| |
| static int do_execve(struct filename *filename, |
| const char __user *const __user *__argv, |
| const char __user *const __user *__envp) |
| { |
| struct user_arg_ptr argv = { .ptr.native = __argv }; |
| struct user_arg_ptr envp = { .ptr.native = __envp }; |
| return do_execveat_common(AT_FDCWD, filename, argv, envp, 0); |
| } |
| |
| static int do_execveat(int fd, struct filename *filename, |
| const char __user *const __user *__argv, |
| const char __user *const __user *__envp, |
| int flags) |
| { |
| struct user_arg_ptr argv = { .ptr.native = __argv }; |
| struct user_arg_ptr envp = { .ptr.native = __envp }; |
| |
| return do_execveat_common(fd, filename, argv, envp, flags); |
| } |
| |
| #ifdef CONFIG_COMPAT |
| static int compat_do_execve(struct filename *filename, |
| const compat_uptr_t __user *__argv, |
| const compat_uptr_t __user *__envp) |
| { |
| struct user_arg_ptr argv = { |
| .is_compat = true, |
| .ptr.compat = __argv, |
| }; |
| struct user_arg_ptr envp = { |
| .is_compat = true, |
| .ptr.compat = __envp, |
| }; |
| return do_execveat_common(AT_FDCWD, filename, argv, envp, 0); |
| } |
| |
| static int compat_do_execveat(int fd, struct filename *filename, |
| const compat_uptr_t __user *__argv, |
| const compat_uptr_t __user *__envp, |
| int flags) |
| { |
| struct user_arg_ptr argv = { |
| .is_compat = true, |
| .ptr.compat = __argv, |
| }; |
| struct user_arg_ptr envp = { |
| .is_compat = true, |
| .ptr.compat = __envp, |
| }; |
| return do_execveat_common(fd, filename, argv, envp, flags); |
| } |
| #endif |
| |
| void set_binfmt(struct linux_binfmt *new) |
| { |
| struct mm_struct *mm = current->mm; |
| |
| if (mm->binfmt) |
| module_put(mm->binfmt->module); |
| |
| mm->binfmt = new; |
| if (new) |
| __module_get(new->module); |
| } |
| EXPORT_SYMBOL(set_binfmt); |
| |
| /* |
| * set_dumpable stores three-value SUID_DUMP_* into mm->flags. |
| */ |
| void set_dumpable(struct mm_struct *mm, int value) |
| { |
| if (WARN_ON((unsigned)value > SUID_DUMP_ROOT)) |
| return; |
| |
| set_mask_bits(&mm->flags, MMF_DUMPABLE_MASK, value); |
| } |
| |
| SYSCALL_DEFINE3(execve, |
| const char __user *, filename, |
| const char __user *const __user *, argv, |
| const char __user *const __user *, envp) |
| { |
| return do_execve(getname(filename), argv, envp); |
| } |
| |
| SYSCALL_DEFINE5(execveat, |
| int, fd, const char __user *, filename, |
| const char __user *const __user *, argv, |
| const char __user *const __user *, envp, |
| int, flags) |
| { |
| return do_execveat(fd, |
| getname_uflags(filename, flags), |
| argv, envp, flags); |
| } |
| |
| #ifdef CONFIG_COMPAT |
| COMPAT_SYSCALL_DEFINE3(execve, const char __user *, filename, |
| const compat_uptr_t __user *, argv, |
| const compat_uptr_t __user *, envp) |
| { |
| return compat_do_execve(getname(filename), argv, envp); |
| } |
| |
| COMPAT_SYSCALL_DEFINE5(execveat, int, fd, |
| const char __user *, filename, |
| const compat_uptr_t __user *, argv, |
| const compat_uptr_t __user *, envp, |
| int, flags) |
| { |
| return compat_do_execveat(fd, |
| getname_uflags(filename, flags), |
| argv, envp, flags); |
| } |
| #endif |
| |
| #ifdef CONFIG_SYSCTL |
| |
| static int proc_dointvec_minmax_coredump(struct ctl_table *table, int write, |
| void *buffer, size_t *lenp, loff_t *ppos) |
| { |
| int error = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
| |
| if (!error) |
| validate_coredump_safety(); |
| return error; |
| } |
| |
| static struct ctl_table fs_exec_sysctls[] = { |
| { |
| .procname = "suid_dumpable", |
| .data = &suid_dumpable, |
| .maxlen = sizeof(int), |
| .mode = 0644, |
| .proc_handler = proc_dointvec_minmax_coredump, |
| .extra1 = SYSCTL_ZERO, |
| .extra2 = SYSCTL_TWO, |
| }, |
| { } |
| }; |
| |
| static int __init init_fs_exec_sysctls(void) |
| { |
| register_sysctl_init("fs", fs_exec_sysctls); |
| return 0; |
| } |
| |
| fs_initcall(init_fs_exec_sysctls); |
| #endif /* CONFIG_SYSCTL */ |