| /* |
| * 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/slab.h> |
| #include <linux/file.h> |
| #include <linux/fdtable.h> |
| #include <linux/mm.h> |
| #include <linux/stat.h> |
| #include <linux/fcntl.h> |
| #include <linux/smp_lock.h> |
| #include <linux/swap.h> |
| #include <linux/string.h> |
| #include <linux/init.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/proc_fs.h> |
| #include <linux/ptrace.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 <asm/uaccess.h> |
| #include <asm/mmu_context.h> |
| #include <asm/tlb.h> |
| |
| #ifdef CONFIG_KMOD |
| #include <linux/kmod.h> |
| #endif |
| |
| #ifdef __alpha__ |
| /* for /sbin/loader handling in search_binary_handler() */ |
| #include <linux/a.out.h> |
| #endif |
| |
| int core_uses_pid; |
| char core_pattern[CORENAME_MAX_SIZE] = "core"; |
| int suid_dumpable = 0; |
| |
| /* The maximal length of core_pattern is also specified in sysctl.c */ |
| |
| static LIST_HEAD(formats); |
| static DEFINE_RWLOCK(binfmt_lock); |
| |
| int register_binfmt(struct linux_binfmt * fmt) |
| { |
| if (!fmt) |
| return -EINVAL; |
| write_lock(&binfmt_lock); |
| list_add(&fmt->lh, &formats); |
| write_unlock(&binfmt_lock); |
| return 0; |
| } |
| |
| 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); |
| } |
| |
| /* |
| * 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 from the file itself. |
| */ |
| asmlinkage long sys_uselib(const char __user * library) |
| { |
| struct file * file; |
| struct nameidata nd; |
| int error; |
| |
| error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC); |
| if (error) |
| goto out; |
| |
| error = -EINVAL; |
| if (!S_ISREG(nd.path.dentry->d_inode->i_mode)) |
| goto exit; |
| |
| error = vfs_permission(&nd, MAY_READ | MAY_EXEC); |
| if (error) |
| goto exit; |
| |
| file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE); |
| error = PTR_ERR(file); |
| if (IS_ERR(file)) |
| goto out; |
| |
| error = -ENOEXEC; |
| if(file->f_op) { |
| struct linux_binfmt * fmt; |
| |
| 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); |
| } |
| fput(file); |
| out: |
| return error; |
| exit: |
| release_open_intent(&nd); |
| path_put(&nd.path); |
| goto out; |
| } |
| |
| #ifdef CONFIG_MMU |
| |
| static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, |
| int write) |
| { |
| struct page *page; |
| int ret; |
| |
| #ifdef CONFIG_STACK_GROWSUP |
| if (write) { |
| ret = expand_stack_downwards(bprm->vma, pos); |
| if (ret < 0) |
| return NULL; |
| } |
| #endif |
| ret = get_user_pages(current, bprm->mm, pos, |
| 1, write, 1, &page, NULL); |
| if (ret <= 0) |
| return NULL; |
| |
| if (write) { |
| unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start; |
| struct rlimit *rlim; |
| |
| /* |
| * We've historically supported up to 32 pages (ARG_MAX) |
| * of argument strings even with small stacks |
| */ |
| if (size <= ARG_MAX) |
| return page; |
| |
| /* |
| * Limit to 1/4-th the stack size 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. |
| */ |
| rlim = current->signal->rlim; |
| if (size > rlim[RLIMIT_STACK].rlim_cur / 4) { |
| put_page(page); |
| return NULL; |
| } |
| } |
| |
| return page; |
| } |
| |
| static void put_arg_page(struct page *page) |
| { |
| put_page(page); |
| } |
| |
| static void free_arg_page(struct linux_binprm *bprm, int i) |
| { |
| } |
| |
| 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 = -ENOMEM; |
| struct vm_area_struct *vma = NULL; |
| struct mm_struct *mm = bprm->mm; |
| |
| bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); |
| if (!vma) |
| goto err; |
| |
| down_write(&mm->mmap_sem); |
| vma->vm_mm = mm; |
| |
| /* |
| * 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. |
| */ |
| vma->vm_end = STACK_TOP_MAX; |
| vma->vm_start = vma->vm_end - PAGE_SIZE; |
| |
| vma->vm_flags = VM_STACK_FLAGS; |
| vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); |
| err = insert_vm_struct(mm, vma); |
| if (err) { |
| up_write(&mm->mmap_sem); |
| goto err; |
| } |
| |
| mm->stack_vm = mm->total_vm = 1; |
| up_write(&mm->mmap_sem); |
| |
| bprm->p = vma->vm_end - sizeof(void *); |
| |
| return 0; |
| |
| err: |
| if (vma) { |
| bprm->vma = NULL; |
| kmem_cache_free(vm_area_cachep, vma); |
| } |
| |
| return err; |
| } |
| |
| static bool valid_arg_len(struct linux_binprm *bprm, long len) |
| { |
| return len <= MAX_ARG_STRLEN; |
| } |
| |
| #else |
| |
| 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(). |
| */ |
| 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; |
| |
| err = init_new_context(current, mm); |
| if (err) |
| goto err; |
| |
| err = __bprm_mm_init(bprm); |
| if (err) |
| goto err; |
| |
| return 0; |
| |
| err: |
| if (mm) { |
| bprm->mm = NULL; |
| mmdrop(mm); |
| } |
| |
| return err; |
| } |
| |
| /* |
| * count() counts the number of strings in array ARGV. |
| */ |
| static int count(char __user * __user * argv, int max) |
| { |
| int i = 0; |
| |
| if (argv != NULL) { |
| for (;;) { |
| char __user * p; |
| |
| if (get_user(p, argv)) |
| return -EFAULT; |
| if (!p) |
| break; |
| argv++; |
| if(++i > max) |
| return -E2BIG; |
| cond_resched(); |
| } |
| } |
| return i; |
| } |
| |
| /* |
| * '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, char __user * __user * argv, |
| struct linux_binprm *bprm) |
| { |
| struct page *kmapped_page = NULL; |
| char *kaddr = NULL; |
| unsigned long kpos = 0; |
| int ret; |
| |
| while (argc-- > 0) { |
| char __user *str; |
| int len; |
| unsigned long pos; |
| |
| if (get_user(str, argv+argc) || |
| !(len = strnlen_user(str, MAX_ARG_STRLEN))) { |
| ret = -EFAULT; |
| goto out; |
| } |
| |
| if (!valid_arg_len(bprm, len)) { |
| ret = -E2BIG; |
| goto out; |
| } |
| |
| /* We're going to work our way backwords. */ |
| pos = bprm->p; |
| str += len; |
| bprm->p -= len; |
| |
| while (len > 0) { |
| int offset, bytes_to_copy; |
| |
| 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_kernel_dcache_page(kmapped_page); |
| kunmap(kmapped_page); |
| put_arg_page(kmapped_page); |
| } |
| kmapped_page = page; |
| kaddr = kmap(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_kernel_dcache_page(kmapped_page); |
| kunmap(kmapped_page); |
| put_arg_page(kmapped_page); |
| } |
| return ret; |
| } |
| |
| /* |
| * Like copy_strings, but get argv and its values from kernel memory. |
| */ |
| int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm) |
| { |
| int r; |
| mm_segment_t oldfs = get_fs(); |
| set_fs(KERNEL_DS); |
| r = copy_strings(argc, (char __user * __user *)argv, bprm); |
| set_fs(oldfs); |
| return r; |
| } |
| EXPORT_SYMBOL(copy_strings_kernel); |
| |
| #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; |
| 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 != find_vma(mm, new_start)) |
| return -EFAULT; |
| |
| /* |
| * cover the whole range: [new_start, old_end) |
| */ |
| vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL); |
| |
| /* |
| * 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)) |
| return -ENOMEM; |
| |
| lru_add_drain(); |
| tlb = tlb_gather_mmu(mm, 0); |
| 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, |
| vma->vm_next ? vma->vm_next->vm_start : 0); |
| } 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, |
| vma->vm_next ? vma->vm_next->vm_start : 0); |
| } |
| tlb_finish_mmu(tlb, new_end, old_end); |
| |
| /* |
| * shrink the vma to just the new range. |
| */ |
| vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL); |
| |
| return 0; |
| } |
| |
| #define EXTRA_STACK_VM_PAGES 20 /* random */ |
| |
| /* |
| * 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; |
| |
| #ifdef CONFIG_STACK_GROWSUP |
| /* Limit stack size to 1GB */ |
| stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max; |
| if (stack_base > (1 << 30)) |
| stack_base = 1 << 30; |
| |
| /* 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); |
| 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; |
| |
| down_write(&mm->mmap_sem); |
| 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; |
| |
| ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end, |
| vm_flags); |
| if (ret) |
| goto out_unlock; |
| BUG_ON(prev != vma); |
| |
| /* Move stack pages down in memory. */ |
| if (stack_shift) { |
| ret = shift_arg_pages(vma, stack_shift); |
| if (ret) { |
| up_write(&mm->mmap_sem); |
| return ret; |
| } |
| } |
| |
| #ifdef CONFIG_STACK_GROWSUP |
| stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE; |
| #else |
| stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE; |
| #endif |
| ret = expand_stack(vma, stack_base); |
| if (ret) |
| ret = -EFAULT; |
| |
| out_unlock: |
| up_write(&mm->mmap_sem); |
| return 0; |
| } |
| EXPORT_SYMBOL(setup_arg_pages); |
| |
| #endif /* CONFIG_MMU */ |
| |
| struct file *open_exec(const char *name) |
| { |
| struct nameidata nd; |
| int err; |
| struct file *file; |
| |
| err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC); |
| file = ERR_PTR(err); |
| |
| if (!err) { |
| struct inode *inode = nd.path.dentry->d_inode; |
| file = ERR_PTR(-EACCES); |
| if (S_ISREG(inode->i_mode)) { |
| int err = vfs_permission(&nd, MAY_EXEC); |
| file = ERR_PTR(err); |
| if (!err) { |
| file = nameidata_to_filp(&nd, |
| O_RDONLY|O_LARGEFILE); |
| if (!IS_ERR(file)) { |
| err = deny_write_access(file); |
| if (err) { |
| fput(file); |
| file = ERR_PTR(err); |
| } |
| } |
| out: |
| return file; |
| } |
| } |
| release_open_intent(&nd); |
| path_put(&nd.path); |
| } |
| goto out; |
| } |
| |
| EXPORT_SYMBOL(open_exec); |
| |
| int kernel_read(struct file *file, unsigned long offset, |
| char *addr, unsigned long count) |
| { |
| mm_segment_t old_fs; |
| loff_t pos = offset; |
| int result; |
| |
| old_fs = get_fs(); |
| set_fs(get_ds()); |
| /* The cast to a user pointer is valid due to the set_fs() */ |
| result = vfs_read(file, (void __user *)addr, count, &pos); |
| set_fs(old_fs); |
| return result; |
| } |
| |
| EXPORT_SYMBOL(kernel_read); |
| |
| static int exec_mmap(struct mm_struct *mm) |
| { |
| struct task_struct *tsk; |
| struct mm_struct * old_mm, *active_mm; |
| |
| /* Notify parent that we're no longer interested in the old VM */ |
| tsk = current; |
| old_mm = current->mm; |
| mm_release(tsk, old_mm); |
| |
| if (old_mm) { |
| /* |
| * Make sure that if there is a core dump in progress |
| * for the old mm, we get out and die instead of going |
| * through with the exec. We must hold mmap_sem around |
| * checking core_state and changing tsk->mm. |
| */ |
| down_read(&old_mm->mmap_sem); |
| if (unlikely(old_mm->core_state)) { |
| up_read(&old_mm->mmap_sem); |
| return -EINTR; |
| } |
| } |
| task_lock(tsk); |
| active_mm = tsk->active_mm; |
| tsk->mm = mm; |
| tsk->active_mm = mm; |
| activate_mm(active_mm, mm); |
| task_unlock(tsk); |
| mm_update_next_owner(old_mm); |
| arch_pick_mmap_layout(mm); |
| if (old_mm) { |
| up_read(&old_mm->mmap_sem); |
| BUG_ON(active_mm != old_mm); |
| mmput(old_mm); |
| return 0; |
| } |
| mmdrop(active_mm); |
| return 0; |
| } |
| |
| /* |
| * 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 de_thread(struct task_struct *tsk) |
| { |
| struct signal_struct *sig = tsk->signal; |
| struct sighand_struct *oldsighand = tsk->sighand; |
| spinlock_t *lock = &oldsighand->siglock; |
| struct task_struct *leader = NULL; |
| int count; |
| |
| if (thread_group_empty(tsk)) |
| goto no_thread_group; |
| |
| /* |
| * Kill all other threads in the thread group. |
| */ |
| spin_lock_irq(lock); |
| if (signal_group_exit(sig)) { |
| /* |
| * Another group action in progress, just |
| * return so that the signal is processed. |
| */ |
| spin_unlock_irq(lock); |
| return -EAGAIN; |
| } |
| sig->group_exit_task = tsk; |
| zap_other_threads(tsk); |
| |
| /* Account for the thread group leader hanging around: */ |
| count = thread_group_leader(tsk) ? 1 : 2; |
| sig->notify_count = count; |
| while (atomic_read(&sig->count) > count) { |
| __set_current_state(TASK_UNINTERRUPTIBLE); |
| spin_unlock_irq(lock); |
| schedule(); |
| 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)) { |
| leader = tsk->group_leader; |
| |
| sig->notify_count = -1; /* for exit_notify() */ |
| for (;;) { |
| write_lock_irq(&tasklist_lock); |
| if (likely(leader->exit_state)) |
| break; |
| __set_current_state(TASK_UNINTERRUPTIBLE); |
| write_unlock_irq(&tasklist_lock); |
| schedule(); |
| } |
| |
| if (unlikely(task_child_reaper(tsk) == leader)) |
| task_active_pid_ns(tsk)->child_reaper = tsk; |
| /* |
| * 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; |
| |
| BUG_ON(!same_thread_group(leader, tsk)); |
| BUG_ON(has_group_leader_pid(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. |
| * Note: The old leader also uses this pid until release_task |
| * is called. Odd but simple and correct. |
| */ |
| detach_pid(tsk, PIDTYPE_PID); |
| tsk->pid = leader->pid; |
| attach_pid(tsk, PIDTYPE_PID, task_pid(leader)); |
| transfer_pid(leader, tsk, PIDTYPE_PGID); |
| transfer_pid(leader, tsk, PIDTYPE_SID); |
| list_replace_rcu(&leader->tasks, &tsk->tasks); |
| |
| tsk->group_leader = tsk; |
| leader->group_leader = tsk; |
| |
| tsk->exit_signal = SIGCHLD; |
| |
| BUG_ON(leader->exit_state != EXIT_ZOMBIE); |
| leader->exit_state = EXIT_DEAD; |
| |
| write_unlock_irq(&tasklist_lock); |
| } |
| |
| sig->group_exit_task = NULL; |
| sig->notify_count = 0; |
| |
| no_thread_group: |
| exit_itimers(sig); |
| flush_itimer_signals(); |
| if (leader) |
| release_task(leader); |
| |
| if (atomic_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; |
| |
| atomic_set(&newsighand->count, 1); |
| memcpy(newsighand->action, oldsighand->action, |
| sizeof(newsighand->action)); |
| |
| write_lock_irq(&tasklist_lock); |
| spin_lock(&oldsighand->siglock); |
| rcu_assign_pointer(tsk->sighand, newsighand); |
| spin_unlock(&oldsighand->siglock); |
| write_unlock_irq(&tasklist_lock); |
| |
| __cleanup_sighand(oldsighand); |
| } |
| |
| BUG_ON(!thread_group_leader(tsk)); |
| return 0; |
| } |
| |
| /* |
| * These functions flushes out all traces of the currently running executable |
| * so that a new one can be started |
| */ |
| static void flush_old_files(struct files_struct * files) |
| { |
| long j = -1; |
| struct fdtable *fdt; |
| |
| spin_lock(&files->file_lock); |
| for (;;) { |
| unsigned long set, i; |
| |
| j++; |
| i = j * __NFDBITS; |
| fdt = files_fdtable(files); |
| if (i >= fdt->max_fds) |
| break; |
| set = fdt->close_on_exec->fds_bits[j]; |
| if (!set) |
| continue; |
| fdt->close_on_exec->fds_bits[j] = 0; |
| spin_unlock(&files->file_lock); |
| for ( ; set ; i++,set >>= 1) { |
| if (set & 1) { |
| sys_close(i); |
| } |
| } |
| spin_lock(&files->file_lock); |
| |
| } |
| spin_unlock(&files->file_lock); |
| } |
| |
| char *get_task_comm(char *buf, struct task_struct *tsk) |
| { |
| /* buf must be at least sizeof(tsk->comm) in size */ |
| task_lock(tsk); |
| strncpy(buf, tsk->comm, sizeof(tsk->comm)); |
| task_unlock(tsk); |
| return buf; |
| } |
| |
| void set_task_comm(struct task_struct *tsk, char *buf) |
| { |
| task_lock(tsk); |
| strlcpy(tsk->comm, buf, sizeof(tsk->comm)); |
| task_unlock(tsk); |
| } |
| |
| int flush_old_exec(struct linux_binprm * bprm) |
| { |
| char * name; |
| int i, ch, retval; |
| char tcomm[sizeof(current->comm)]; |
| |
| /* |
| * Make sure we have a private signal table and that |
| * we are unassociated from the previous thread group. |
| */ |
| retval = de_thread(current); |
| if (retval) |
| goto out; |
| |
| set_mm_exe_file(bprm->mm, bprm->file); |
| |
| /* |
| * Release all of the old mmap stuff |
| */ |
| retval = exec_mmap(bprm->mm); |
| if (retval) |
| goto out; |
| |
| bprm->mm = NULL; /* We're using it now */ |
| |
| /* This is the point of no return */ |
| current->sas_ss_sp = current->sas_ss_size = 0; |
| |
| if (current->euid == current->uid && current->egid == current->gid) |
| set_dumpable(current->mm, 1); |
| else |
| set_dumpable(current->mm, suid_dumpable); |
| |
| name = bprm->filename; |
| |
| /* Copies the binary name from after last slash */ |
| for (i=0; (ch = *(name++)) != '\0';) { |
| if (ch == '/') |
| i = 0; /* overwrite what we wrote */ |
| else |
| if (i < (sizeof(tcomm) - 1)) |
| tcomm[i++] = ch; |
| } |
| tcomm[i] = '\0'; |
| set_task_comm(current, tcomm); |
| |
| current->flags &= ~PF_RANDOMIZE; |
| flush_thread(); |
| |
| /* 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 |
| */ |
| current->mm->task_size = TASK_SIZE; |
| |
| if (bprm->e_uid != current->euid || bprm->e_gid != current->egid) { |
| suid_keys(current); |
| set_dumpable(current->mm, suid_dumpable); |
| current->pdeath_signal = 0; |
| } else if (file_permission(bprm->file, MAY_READ) || |
| (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) { |
| suid_keys(current); |
| set_dumpable(current->mm, suid_dumpable); |
| } |
| |
| /* An exec changes our domain. We are no longer part of the thread |
| group */ |
| |
| current->self_exec_id++; |
| |
| flush_signal_handlers(current, 0); |
| flush_old_files(current->files); |
| |
| return 0; |
| |
| out: |
| return retval; |
| } |
| |
| EXPORT_SYMBOL(flush_old_exec); |
| |
| /* |
| * Fill the binprm structure from the inode. |
| * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes |
| */ |
| int prepare_binprm(struct linux_binprm *bprm) |
| { |
| int mode; |
| struct inode * inode = bprm->file->f_path.dentry->d_inode; |
| int retval; |
| |
| mode = inode->i_mode; |
| if (bprm->file->f_op == NULL) |
| return -EACCES; |
| |
| bprm->e_uid = current->euid; |
| bprm->e_gid = current->egid; |
| |
| if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) { |
| /* Set-uid? */ |
| if (mode & S_ISUID) { |
| current->personality &= ~PER_CLEAR_ON_SETID; |
| bprm->e_uid = inode->i_uid; |
| } |
| |
| /* Set-gid? */ |
| /* |
| * If setgid is set but no group execute bit then this |
| * is a candidate for mandatory locking, not a setgid |
| * executable. |
| */ |
| if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { |
| current->personality &= ~PER_CLEAR_ON_SETID; |
| bprm->e_gid = inode->i_gid; |
| } |
| } |
| |
| /* fill in binprm security blob */ |
| retval = security_bprm_set(bprm); |
| if (retval) |
| return retval; |
| |
| memset(bprm->buf,0,BINPRM_BUF_SIZE); |
| return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE); |
| } |
| |
| EXPORT_SYMBOL(prepare_binprm); |
| |
| static int unsafe_exec(struct task_struct *p) |
| { |
| int unsafe = 0; |
| if (p->ptrace & PT_PTRACED) { |
| if (p->ptrace & PT_PTRACE_CAP) |
| unsafe |= LSM_UNSAFE_PTRACE_CAP; |
| else |
| unsafe |= LSM_UNSAFE_PTRACE; |
| } |
| if (atomic_read(&p->fs->count) > 1 || |
| atomic_read(&p->files->count) > 1 || |
| atomic_read(&p->sighand->count) > 1) |
| unsafe |= LSM_UNSAFE_SHARE; |
| |
| return unsafe; |
| } |
| |
| void compute_creds(struct linux_binprm *bprm) |
| { |
| int unsafe; |
| |
| if (bprm->e_uid != current->uid) { |
| suid_keys(current); |
| current->pdeath_signal = 0; |
| } |
| exec_keys(current); |
| |
| task_lock(current); |
| unsafe = unsafe_exec(current); |
| security_bprm_apply_creds(bprm, unsafe); |
| task_unlock(current); |
| security_bprm_post_apply_creds(bprm); |
| } |
| EXPORT_SYMBOL(compute_creds); |
| |
| /* |
| * 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_atomic(page, KM_USER0); |
| |
| for (; offset < PAGE_SIZE && kaddr[offset]; |
| offset++, bprm->p++) |
| ; |
| |
| kunmap_atomic(kaddr, KM_USER0); |
| put_arg_page(page); |
| |
| if (offset == PAGE_SIZE) |
| free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1); |
| } while (offset == PAGE_SIZE); |
| |
| bprm->p++; |
| bprm->argc--; |
| ret = 0; |
| |
| out: |
| return ret; |
| } |
| EXPORT_SYMBOL(remove_arg_zero); |
| |
| /* |
| * cycle the list of binary formats handler, until one recognizes the image |
| */ |
| int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs) |
| { |
| int try,retval; |
| struct linux_binfmt *fmt; |
| #ifdef __alpha__ |
| /* handle /sbin/loader.. */ |
| { |
| struct exec * eh = (struct exec *) bprm->buf; |
| |
| if (!bprm->loader && eh->fh.f_magic == 0x183 && |
| (eh->fh.f_flags & 0x3000) == 0x3000) |
| { |
| struct file * file; |
| unsigned long loader; |
| |
| allow_write_access(bprm->file); |
| fput(bprm->file); |
| bprm->file = NULL; |
| |
| loader = bprm->vma->vm_end - sizeof(void *); |
| |
| file = open_exec("/sbin/loader"); |
| retval = PTR_ERR(file); |
| if (IS_ERR(file)) |
| return retval; |
| |
| /* Remember if the application is TASO. */ |
| bprm->sh_bang = eh->ah.entry < 0x100000000UL; |
| |
| bprm->file = file; |
| bprm->loader = loader; |
| retval = prepare_binprm(bprm); |
| if (retval<0) |
| return retval; |
| /* should call search_binary_handler recursively here, |
| but it does not matter */ |
| } |
| } |
| #endif |
| retval = security_bprm_check(bprm); |
| if (retval) |
| return retval; |
| |
| /* kernel module loader fixup */ |
| /* so we don't try to load run modprobe in kernel space. */ |
| set_fs(USER_DS); |
| |
| retval = audit_bprm(bprm); |
| if (retval) |
| return retval; |
| |
| retval = -ENOENT; |
| for (try=0; try<2; try++) { |
| read_lock(&binfmt_lock); |
| list_for_each_entry(fmt, &formats, lh) { |
| int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary; |
| if (!fn) |
| continue; |
| if (!try_module_get(fmt->module)) |
| continue; |
| read_unlock(&binfmt_lock); |
| retval = fn(bprm, regs); |
| if (retval >= 0) { |
| put_binfmt(fmt); |
| allow_write_access(bprm->file); |
| if (bprm->file) |
| fput(bprm->file); |
| bprm->file = NULL; |
| current->did_exec = 1; |
| proc_exec_connector(current); |
| return retval; |
| } |
| read_lock(&binfmt_lock); |
| put_binfmt(fmt); |
| if (retval != -ENOEXEC || bprm->mm == NULL) |
| break; |
| if (!bprm->file) { |
| read_unlock(&binfmt_lock); |
| return retval; |
| } |
| } |
| read_unlock(&binfmt_lock); |
| if (retval != -ENOEXEC || bprm->mm == NULL) { |
| break; |
| #ifdef CONFIG_KMOD |
| }else{ |
| #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e)) |
| if (printable(bprm->buf[0]) && |
| printable(bprm->buf[1]) && |
| printable(bprm->buf[2]) && |
| printable(bprm->buf[3])) |
| break; /* -ENOEXEC */ |
| request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2])); |
| #endif |
| } |
| } |
| return retval; |
| } |
| |
| EXPORT_SYMBOL(search_binary_handler); |
| |
| void free_bprm(struct linux_binprm *bprm) |
| { |
| free_arg_pages(bprm); |
| kfree(bprm); |
| } |
| |
| /* |
| * sys_execve() executes a new program. |
| */ |
| int do_execve(char * filename, |
| char __user *__user *argv, |
| char __user *__user *envp, |
| struct pt_regs * regs) |
| { |
| struct linux_binprm *bprm; |
| struct file *file; |
| struct files_struct *displaced; |
| int retval; |
| |
| retval = unshare_files(&displaced); |
| if (retval) |
| goto out_ret; |
| |
| retval = -ENOMEM; |
| bprm = kzalloc(sizeof(*bprm), GFP_KERNEL); |
| if (!bprm) |
| goto out_files; |
| |
| file = open_exec(filename); |
| retval = PTR_ERR(file); |
| if (IS_ERR(file)) |
| goto out_kfree; |
| |
| sched_exec(); |
| |
| bprm->file = file; |
| bprm->filename = filename; |
| bprm->interp = filename; |
| |
| retval = bprm_mm_init(bprm); |
| if (retval) |
| goto out_file; |
| |
| bprm->argc = count(argv, MAX_ARG_STRINGS); |
| if ((retval = bprm->argc) < 0) |
| goto out_mm; |
| |
| bprm->envc = count(envp, MAX_ARG_STRINGS); |
| if ((retval = bprm->envc) < 0) |
| goto out_mm; |
| |
| retval = security_bprm_alloc(bprm); |
| if (retval) |
| goto out; |
| |
| retval = prepare_binprm(bprm); |
| if (retval < 0) |
| goto out; |
| |
| retval = copy_strings_kernel(1, &bprm->filename, bprm); |
| if (retval < 0) |
| goto out; |
| |
| bprm->exec = bprm->p; |
| retval = copy_strings(bprm->envc, envp, bprm); |
| if (retval < 0) |
| goto out; |
| |
| retval = copy_strings(bprm->argc, argv, bprm); |
| if (retval < 0) |
| goto out; |
| |
| current->flags &= ~PF_KTHREAD; |
| retval = search_binary_handler(bprm,regs); |
| if (retval >= 0) { |
| /* execve success */ |
| security_bprm_free(bprm); |
| acct_update_integrals(current); |
| free_bprm(bprm); |
| if (displaced) |
| put_files_struct(displaced); |
| return retval; |
| } |
| |
| out: |
| if (bprm->security) |
| security_bprm_free(bprm); |
| |
| out_mm: |
| if (bprm->mm) |
| mmput (bprm->mm); |
| |
| out_file: |
| if (bprm->file) { |
| allow_write_access(bprm->file); |
| fput(bprm->file); |
| } |
| out_kfree: |
| free_bprm(bprm); |
| |
| out_files: |
| if (displaced) |
| reset_files_struct(displaced); |
| out_ret: |
| return retval; |
| } |
| |
| int set_binfmt(struct linux_binfmt *new) |
| { |
| struct linux_binfmt *old = current->binfmt; |
| |
| if (new) { |
| if (!try_module_get(new->module)) |
| return -1; |
| } |
| current->binfmt = new; |
| if (old) |
| module_put(old->module); |
| return 0; |
| } |
| |
| EXPORT_SYMBOL(set_binfmt); |
| |
| /* format_corename will inspect the pattern parameter, and output a |
| * name into corename, which must have space for at least |
| * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator. |
| */ |
| static int format_corename(char *corename, const char *pattern, long signr) |
| { |
| const char *pat_ptr = pattern; |
| char *out_ptr = corename; |
| char *const out_end = corename + CORENAME_MAX_SIZE; |
| int rc; |
| int pid_in_pattern = 0; |
| int ispipe = 0; |
| |
| if (*pattern == '|') |
| ispipe = 1; |
| |
| /* Repeat as long as we have more pattern to process and more output |
| space */ |
| while (*pat_ptr) { |
| if (*pat_ptr != '%') { |
| if (out_ptr == out_end) |
| goto out; |
| *out_ptr++ = *pat_ptr++; |
| } else { |
| switch (*++pat_ptr) { |
| case 0: |
| goto out; |
| /* Double percent, output one percent */ |
| case '%': |
| if (out_ptr == out_end) |
| goto out; |
| *out_ptr++ = '%'; |
| break; |
| /* pid */ |
| case 'p': |
| pid_in_pattern = 1; |
| rc = snprintf(out_ptr, out_end - out_ptr, |
| "%d", task_tgid_vnr(current)); |
| if (rc > out_end - out_ptr) |
| goto out; |
| out_ptr += rc; |
| break; |
| /* uid */ |
| case 'u': |
| rc = snprintf(out_ptr, out_end - out_ptr, |
| "%d", current->uid); |
| if (rc > out_end - out_ptr) |
| goto out; |
| out_ptr += rc; |
| break; |
| /* gid */ |
| case 'g': |
| rc = snprintf(out_ptr, out_end - out_ptr, |
| "%d", current->gid); |
| if (rc > out_end - out_ptr) |
| goto out; |
| out_ptr += rc; |
| break; |
| /* signal that caused the coredump */ |
| case 's': |
| rc = snprintf(out_ptr, out_end - out_ptr, |
| "%ld", signr); |
| if (rc > out_end - out_ptr) |
| goto out; |
| out_ptr += rc; |
| break; |
| /* UNIX time of coredump */ |
| case 't': { |
| struct timeval tv; |
| do_gettimeofday(&tv); |
| rc = snprintf(out_ptr, out_end - out_ptr, |
| "%lu", tv.tv_sec); |
| if (rc > out_end - out_ptr) |
| goto out; |
| out_ptr += rc; |
| break; |
| } |
| /* hostname */ |
| case 'h': |
| down_read(&uts_sem); |
| rc = snprintf(out_ptr, out_end - out_ptr, |
| "%s", utsname()->nodename); |
| up_read(&uts_sem); |
| if (rc > out_end - out_ptr) |
| goto out; |
| out_ptr += rc; |
| break; |
| /* executable */ |
| case 'e': |
| rc = snprintf(out_ptr, out_end - out_ptr, |
| "%s", current->comm); |
| if (rc > out_end - out_ptr) |
| goto out; |
| out_ptr += rc; |
| break; |
| /* core limit size */ |
| case 'c': |
| rc = snprintf(out_ptr, out_end - out_ptr, |
| "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur); |
| if (rc > out_end - out_ptr) |
| goto out; |
| out_ptr += rc; |
| break; |
| default: |
| break; |
| } |
| ++pat_ptr; |
| } |
| } |
| /* Backward compatibility with core_uses_pid: |
| * |
| * If core_pattern does not include a %p (as is the default) |
| * and core_uses_pid is set, then .%pid will be appended to |
| * the filename. Do not do this for piped commands. */ |
| if (!ispipe && !pid_in_pattern |
| && (core_uses_pid || atomic_read(¤t->mm->mm_users) != 1)) { |
| rc = snprintf(out_ptr, out_end - out_ptr, |
| ".%d", task_tgid_vnr(current)); |
| if (rc > out_end - out_ptr) |
| goto out; |
| out_ptr += rc; |
| } |
| out: |
| *out_ptr = 0; |
| return ispipe; |
| } |
| |
| static void zap_process(struct task_struct *start) |
| { |
| struct task_struct *t; |
| |
| start->signal->flags = SIGNAL_GROUP_EXIT; |
| start->signal->group_stop_count = 0; |
| |
| t = start; |
| do { |
| if (t != current && t->mm) { |
| t->mm->core_state->nr_threads++; |
| sigaddset(&t->pending.signal, SIGKILL); |
| signal_wake_up(t, 1); |
| } |
| } while_each_thread(start, t); |
| } |
| |
| static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm, |
| int exit_code) |
| { |
| struct task_struct *g, *p; |
| unsigned long flags; |
| int err = -EAGAIN; |
| |
| spin_lock_irq(&tsk->sighand->siglock); |
| if (!signal_group_exit(tsk->signal)) { |
| tsk->signal->group_exit_code = exit_code; |
| zap_process(tsk); |
| err = 0; |
| } |
| spin_unlock_irq(&tsk->sighand->siglock); |
| if (err) |
| return err; |
| |
| if (atomic_read(&mm->mm_users) == mm->core_state->nr_threads + 1) |
| goto done; |
| /* |
| * We should find and kill all tasks which use this mm, and we should |
| * count them correctly into ->nr_threads. We don't take tasklist |
| * lock, but this is safe wrt: |
| * |
| * fork: |
| * None of sub-threads can fork after zap_process(leader). All |
| * processes which were created before this point should be |
| * visible to zap_threads() because copy_process() adds the new |
| * process to the tail of init_task.tasks list, and lock/unlock |
| * of ->siglock provides a memory barrier. |
| * |
| * do_exit: |
| * The caller holds mm->mmap_sem. This means that the task which |
| * uses this mm can't pass exit_mm(), so it can't exit or clear |
| * its ->mm. |
| * |
| * de_thread: |
| * It does list_replace_rcu(&leader->tasks, ¤t->tasks), |
| * we must see either old or new leader, this does not matter. |
| * However, it can change p->sighand, so lock_task_sighand(p) |
| * must be used. Since p->mm != NULL and we hold ->mmap_sem |
| * it can't fail. |
| * |
| * Note also that "g" can be the old leader with ->mm == NULL |
| * and already unhashed and thus removed from ->thread_group. |
| * This is OK, __unhash_process()->list_del_rcu() does not |
| * clear the ->next pointer, we will find the new leader via |
| * next_thread(). |
| */ |
| rcu_read_lock(); |
| for_each_process(g) { |
| if (g == tsk->group_leader) |
| continue; |
| if (g->flags & PF_KTHREAD) |
| continue; |
| p = g; |
| do { |
| if (p->mm) { |
| if (unlikely(p->mm == mm)) { |
| lock_task_sighand(p, &flags); |
| zap_process(p); |
| unlock_task_sighand(p, &flags); |
| } |
| break; |
| } |
| } while_each_thread(g, p); |
| } |
| rcu_read_unlock(); |
| done: |
| return mm->core_state->nr_threads; |
| } |
| |
| static int coredump_wait(int exit_code) |
| { |
| struct task_struct *tsk = current; |
| struct mm_struct *mm = tsk->mm; |
| struct core_state core_state; |
| struct completion *vfork_done; |
| int core_waiters; |
| |
| init_completion(&mm->core_done); |
| init_completion(&core_state.startup); |
| core_state.nr_threads = 0; |
| mm->core_state = &core_state; |
| |
| core_waiters = zap_threads(tsk, mm, exit_code); |
| if (core_waiters < 0) |
| mm->core_state = NULL; |
| up_write(&mm->mmap_sem); |
| |
| if (unlikely(core_waiters < 0)) |
| goto fail; |
| |
| /* |
| * Make sure nobody is waiting for us to release the VM, |
| * otherwise we can deadlock when we wait on each other |
| */ |
| vfork_done = tsk->vfork_done; |
| if (vfork_done) { |
| tsk->vfork_done = NULL; |
| complete(vfork_done); |
| } |
| |
| if (core_waiters) |
| wait_for_completion(&core_state.startup); |
| mm->core_state = NULL; |
| fail: |
| return core_waiters; |
| } |
| |
| /* |
| * set_dumpable converts traditional three-value dumpable to two flags and |
| * stores them into mm->flags. It modifies lower two bits of mm->flags, but |
| * these bits are not changed atomically. So get_dumpable can observe the |
| * intermediate state. To avoid doing unexpected behavior, get get_dumpable |
| * return either old dumpable or new one by paying attention to the order of |
| * modifying the bits. |
| * |
| * dumpable | mm->flags (binary) |
| * old new | initial interim final |
| * ---------+----------------------- |
| * 0 1 | 00 01 01 |
| * 0 2 | 00 10(*) 11 |
| * 1 0 | 01 00 00 |
| * 1 2 | 01 11 11 |
| * 2 0 | 11 10(*) 00 |
| * 2 1 | 11 11 01 |
| * |
| * (*) get_dumpable regards interim value of 10 as 11. |
| */ |
| void set_dumpable(struct mm_struct *mm, int value) |
| { |
| switch (value) { |
| case 0: |
| clear_bit(MMF_DUMPABLE, &mm->flags); |
| smp_wmb(); |
| clear_bit(MMF_DUMP_SECURELY, &mm->flags); |
| break; |
| case 1: |
| set_bit(MMF_DUMPABLE, &mm->flags); |
| smp_wmb(); |
| clear_bit(MMF_DUMP_SECURELY, &mm->flags); |
| break; |
| case 2: |
| set_bit(MMF_DUMP_SECURELY, &mm->flags); |
| smp_wmb(); |
| set_bit(MMF_DUMPABLE, &mm->flags); |
| break; |
| } |
| } |
| |
| int get_dumpable(struct mm_struct *mm) |
| { |
| int ret; |
| |
| ret = mm->flags & 0x3; |
| return (ret >= 2) ? 2 : ret; |
| } |
| |
| int do_coredump(long signr, int exit_code, struct pt_regs * regs) |
| { |
| char corename[CORENAME_MAX_SIZE + 1]; |
| struct mm_struct *mm = current->mm; |
| struct linux_binfmt * binfmt; |
| struct inode * inode; |
| struct file * file; |
| int retval = 0; |
| int fsuid = current->fsuid; |
| int flag = 0; |
| int ispipe = 0; |
| unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur; |
| char **helper_argv = NULL; |
| int helper_argc = 0; |
| char *delimit; |
| |
| audit_core_dumps(signr); |
| |
| binfmt = current->binfmt; |
| if (!binfmt || !binfmt->core_dump) |
| goto fail; |
| down_write(&mm->mmap_sem); |
| /* |
| * If another thread got here first, or we are not dumpable, bail out. |
| */ |
| if (mm->core_state || !get_dumpable(mm)) { |
| up_write(&mm->mmap_sem); |
| goto fail; |
| } |
| |
| /* |
| * We cannot trust fsuid as being the "true" uid of the |
| * process nor do we know its entire history. We only know it |
| * was tainted so we dump it as root in mode 2. |
| */ |
| if (get_dumpable(mm) == 2) { /* Setuid core dump mode */ |
| flag = O_EXCL; /* Stop rewrite attacks */ |
| current->fsuid = 0; /* Dump root private */ |
| } |
| |
| retval = coredump_wait(exit_code); |
| if (retval < 0) |
| goto fail; |
| |
| /* |
| * Clear any false indication of pending signals that might |
| * be seen by the filesystem code called to write the core file. |
| */ |
| clear_thread_flag(TIF_SIGPENDING); |
| |
| /* |
| * lock_kernel() because format_corename() is controlled by sysctl, which |
| * uses lock_kernel() |
| */ |
| lock_kernel(); |
| ispipe = format_corename(corename, core_pattern, signr); |
| unlock_kernel(); |
| /* |
| * Don't bother to check the RLIMIT_CORE value if core_pattern points |
| * to a pipe. Since we're not writing directly to the filesystem |
| * RLIMIT_CORE doesn't really apply, as no actual core file will be |
| * created unless the pipe reader choses to write out the core file |
| * at which point file size limits and permissions will be imposed |
| * as it does with any other process |
| */ |
| if ((!ispipe) && (core_limit < binfmt->min_coredump)) |
| goto fail_unlock; |
| |
| if (ispipe) { |
| helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc); |
| /* Terminate the string before the first option */ |
| delimit = strchr(corename, ' '); |
| if (delimit) |
| *delimit = '\0'; |
| delimit = strrchr(helper_argv[0], '/'); |
| if (delimit) |
| delimit++; |
| else |
| delimit = helper_argv[0]; |
| if (!strcmp(delimit, current->comm)) { |
| printk(KERN_NOTICE "Recursive core dump detected, " |
| "aborting\n"); |
| goto fail_unlock; |
| } |
| |
| core_limit = RLIM_INFINITY; |
| |
| /* SIGPIPE can happen, but it's just never processed */ |
| if (call_usermodehelper_pipe(corename+1, helper_argv, NULL, |
| &file)) { |
| printk(KERN_INFO "Core dump to %s pipe failed\n", |
| corename); |
| goto fail_unlock; |
| } |
| } else |
| file = filp_open(corename, |
| O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag, |
| 0600); |
| if (IS_ERR(file)) |
| goto fail_unlock; |
| inode = file->f_path.dentry->d_inode; |
| if (inode->i_nlink > 1) |
| goto close_fail; /* multiple links - don't dump */ |
| if (!ispipe && d_unhashed(file->f_path.dentry)) |
| goto close_fail; |
| |
| /* AK: actually i see no reason to not allow this for named pipes etc., |
| but keep the previous behaviour for now. */ |
| if (!ispipe && !S_ISREG(inode->i_mode)) |
| goto close_fail; |
| /* |
| * Dont allow local users get cute and trick others to coredump |
| * into their pre-created files: |
| */ |
| if (inode->i_uid != current->fsuid) |
| goto close_fail; |
| if (!file->f_op) |
| goto close_fail; |
| if (!file->f_op->write) |
| goto close_fail; |
| if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0) |
| goto close_fail; |
| |
| retval = binfmt->core_dump(signr, regs, file, core_limit); |
| |
| if (retval) |
| current->signal->group_exit_code |= 0x80; |
| close_fail: |
| filp_close(file, NULL); |
| fail_unlock: |
| if (helper_argv) |
| argv_free(helper_argv); |
| |
| current->fsuid = fsuid; |
| complete_all(&mm->core_done); |
| fail: |
| return retval; |
| } |