![Ying Han](/assets/img/avatar_default.png)
It's pointless to kill a task if another thread sharing its mm cannot be killed to allow future memory freeing. A subsequent patch will prevent kills in such cases, but first it's necessary to have a way to flag a task that shares memory with an OOM_DISABLE task that doesn't incur an additional tasklist scan, which would make select_bad_process() an O(n^2) function. This patch adds an atomic counter to struct mm_struct that follows how many threads attached to it have an oom_score_adj of OOM_SCORE_ADJ_MIN. They cannot be killed by the kernel, so their memory cannot be freed in oom conditions. This only requires task_lock() on the task that we're operating on, it does not require mm->mmap_sem since task_lock() pins the mm and the operation is atomic. [rientjes@google.com: changelog and sys_unshare() code] [rientjes@google.com: protect oom_disable_count with task_lock in fork] [rientjes@google.com: use old_mm for oom_disable_count in exec] Signed-off-by: Ying Han <yinghan@google.com> Signed-off-by: David Rientjes <rientjes@google.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2062 lines
48 KiB
C
2062 lines
48 KiB
C
/*
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* linux/fs/exec.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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/*
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* #!-checking implemented by tytso.
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*/
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/*
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* Demand-loading implemented 01.12.91 - no need to read anything but
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* the header into memory. The inode of the executable is put into
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* "current->executable", and page faults do the actual loading. Clean.
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*
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* Once more I can proudly say that linux stood up to being changed: it
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* was less than 2 hours work to get demand-loading completely implemented.
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*
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* Demand loading changed July 1993 by Eric Youngdale. Use mmap instead,
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* current->executable is only used by the procfs. This allows a dispatch
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* table to check for several different types of binary formats. We keep
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* trying until we recognize the file or we run out of supported binary
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* formats.
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*/
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#include <linux/slab.h>
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#include <linux/file.h>
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#include <linux/fdtable.h>
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#include <linux/mm.h>
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#include <linux/stat.h>
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#include <linux/fcntl.h>
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#include <linux/swap.h>
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#include <linux/string.h>
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#include <linux/init.h>
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#include <linux/pagemap.h>
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#include <linux/perf_event.h>
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#include <linux/highmem.h>
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#include <linux/spinlock.h>
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#include <linux/key.h>
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#include <linux/personality.h>
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#include <linux/binfmts.h>
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#include <linux/utsname.h>
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#include <linux/pid_namespace.h>
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#include <linux/module.h>
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#include <linux/namei.h>
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#include <linux/proc_fs.h>
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#include <linux/mount.h>
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#include <linux/security.h>
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#include <linux/syscalls.h>
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#include <linux/tsacct_kern.h>
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#include <linux/cn_proc.h>
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#include <linux/audit.h>
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#include <linux/tracehook.h>
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#include <linux/kmod.h>
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#include <linux/fsnotify.h>
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#include <linux/fs_struct.h>
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#include <linux/pipe_fs_i.h>
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#include <linux/oom.h>
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#include <asm/uaccess.h>
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#include <asm/mmu_context.h>
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#include <asm/tlb.h>
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#include "internal.h"
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int core_uses_pid;
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char core_pattern[CORENAME_MAX_SIZE] = "core";
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unsigned int core_pipe_limit;
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int suid_dumpable = 0;
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/* The maximal length of core_pattern is also specified in sysctl.c */
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static LIST_HEAD(formats);
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static DEFINE_RWLOCK(binfmt_lock);
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int __register_binfmt(struct linux_binfmt * fmt, int insert)
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{
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if (!fmt)
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return -EINVAL;
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write_lock(&binfmt_lock);
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insert ? list_add(&fmt->lh, &formats) :
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list_add_tail(&fmt->lh, &formats);
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write_unlock(&binfmt_lock);
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return 0;
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}
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EXPORT_SYMBOL(__register_binfmt);
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void unregister_binfmt(struct linux_binfmt * fmt)
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{
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write_lock(&binfmt_lock);
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list_del(&fmt->lh);
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write_unlock(&binfmt_lock);
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}
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EXPORT_SYMBOL(unregister_binfmt);
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static inline void put_binfmt(struct linux_binfmt * fmt)
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{
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module_put(fmt->module);
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}
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/*
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* Note that a shared library must be both readable and executable due to
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* security reasons.
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*
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* Also note that we take the address to load from from the file itself.
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*/
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SYSCALL_DEFINE1(uselib, const char __user *, library)
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{
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struct file *file;
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char *tmp = getname(library);
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int error = PTR_ERR(tmp);
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if (IS_ERR(tmp))
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goto out;
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file = do_filp_open(AT_FDCWD, tmp,
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O_LARGEFILE | O_RDONLY | FMODE_EXEC, 0,
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MAY_READ | MAY_EXEC | MAY_OPEN);
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putname(tmp);
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error = PTR_ERR(file);
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if (IS_ERR(file))
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goto out;
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error = -EINVAL;
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if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
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goto exit;
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error = -EACCES;
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if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
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goto exit;
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fsnotify_open(file);
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error = -ENOEXEC;
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if(file->f_op) {
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struct linux_binfmt * fmt;
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read_lock(&binfmt_lock);
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list_for_each_entry(fmt, &formats, lh) {
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if (!fmt->load_shlib)
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continue;
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if (!try_module_get(fmt->module))
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continue;
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read_unlock(&binfmt_lock);
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error = fmt->load_shlib(file);
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read_lock(&binfmt_lock);
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put_binfmt(fmt);
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if (error != -ENOEXEC)
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break;
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}
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read_unlock(&binfmt_lock);
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}
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exit:
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fput(file);
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out:
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return error;
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}
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#ifdef CONFIG_MMU
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static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
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int write)
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{
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struct page *page;
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int ret;
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#ifdef CONFIG_STACK_GROWSUP
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if (write) {
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ret = expand_stack_downwards(bprm->vma, pos);
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if (ret < 0)
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return NULL;
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}
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#endif
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ret = get_user_pages(current, bprm->mm, pos,
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1, write, 1, &page, NULL);
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if (ret <= 0)
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return NULL;
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if (write) {
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unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
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struct rlimit *rlim;
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/*
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* We've historically supported up to 32 pages (ARG_MAX)
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* of argument strings even with small stacks
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*/
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if (size <= ARG_MAX)
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return page;
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/*
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* Limit to 1/4-th the stack size for the argv+env strings.
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* This ensures that:
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* - the remaining binfmt code will not run out of stack space,
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* - the program will have a reasonable amount of stack left
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* to work from.
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*/
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rlim = current->signal->rlim;
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if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
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put_page(page);
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return NULL;
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}
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}
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return page;
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}
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static void put_arg_page(struct page *page)
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{
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put_page(page);
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}
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static void free_arg_page(struct linux_binprm *bprm, int i)
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{
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}
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static void free_arg_pages(struct linux_binprm *bprm)
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{
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}
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static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
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struct page *page)
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{
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flush_cache_page(bprm->vma, pos, page_to_pfn(page));
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}
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static int __bprm_mm_init(struct linux_binprm *bprm)
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{
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int err;
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struct vm_area_struct *vma = NULL;
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struct mm_struct *mm = bprm->mm;
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bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
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if (!vma)
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return -ENOMEM;
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down_write(&mm->mmap_sem);
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vma->vm_mm = mm;
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/*
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* Place the stack at the largest stack address the architecture
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* supports. Later, we'll move this to an appropriate place. We don't
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* use STACK_TOP because that can depend on attributes which aren't
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* configured yet.
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*/
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BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
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vma->vm_end = STACK_TOP_MAX;
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vma->vm_start = vma->vm_end - PAGE_SIZE;
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vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
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vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
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INIT_LIST_HEAD(&vma->anon_vma_chain);
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err = insert_vm_struct(mm, vma);
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if (err)
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goto err;
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mm->stack_vm = mm->total_vm = 1;
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up_write(&mm->mmap_sem);
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bprm->p = vma->vm_end - sizeof(void *);
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return 0;
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err:
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up_write(&mm->mmap_sem);
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bprm->vma = NULL;
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kmem_cache_free(vm_area_cachep, vma);
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return err;
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}
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static bool valid_arg_len(struct linux_binprm *bprm, long len)
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{
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return len <= MAX_ARG_STRLEN;
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}
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#else
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static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
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int write)
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{
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struct page *page;
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page = bprm->page[pos / PAGE_SIZE];
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if (!page && write) {
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page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
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if (!page)
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return NULL;
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bprm->page[pos / PAGE_SIZE] = page;
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}
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return page;
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}
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static void put_arg_page(struct page *page)
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{
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}
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static void free_arg_page(struct linux_binprm *bprm, int i)
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{
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if (bprm->page[i]) {
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__free_page(bprm->page[i]);
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bprm->page[i] = NULL;
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}
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}
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static void free_arg_pages(struct linux_binprm *bprm)
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{
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int i;
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for (i = 0; i < MAX_ARG_PAGES; i++)
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free_arg_page(bprm, i);
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}
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static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
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struct page *page)
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{
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}
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static int __bprm_mm_init(struct linux_binprm *bprm)
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{
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bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
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return 0;
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}
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static bool valid_arg_len(struct linux_binprm *bprm, long len)
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{
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return len <= bprm->p;
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}
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#endif /* CONFIG_MMU */
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/*
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* Create a new mm_struct and populate it with a temporary stack
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* vm_area_struct. We don't have enough context at this point to set the stack
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* flags, permissions, and offset, so we use temporary values. We'll update
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* them later in setup_arg_pages().
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*/
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int bprm_mm_init(struct linux_binprm *bprm)
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{
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int err;
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struct mm_struct *mm = NULL;
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bprm->mm = mm = mm_alloc();
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err = -ENOMEM;
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if (!mm)
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goto err;
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err = init_new_context(current, mm);
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if (err)
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goto err;
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err = __bprm_mm_init(bprm);
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if (err)
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goto err;
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return 0;
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err:
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if (mm) {
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bprm->mm = NULL;
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mmdrop(mm);
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}
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return err;
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}
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/*
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* count() counts the number of strings in array ARGV.
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*/
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static int count(const char __user * const __user * argv, int max)
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{
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int i = 0;
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if (argv != NULL) {
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for (;;) {
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const char __user * p;
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if (get_user(p, argv))
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return -EFAULT;
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if (!p)
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break;
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argv++;
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if (i++ >= max)
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return -E2BIG;
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|
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if (fatal_signal_pending(current))
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return -ERESTARTNOHAND;
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cond_resched();
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}
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}
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return i;
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}
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/*
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* 'copy_strings()' copies argument/environment strings from the old
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* processes's memory to the new process's stack. The call to get_user_pages()
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* ensures the destination page is created and not swapped out.
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*/
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static int copy_strings(int argc, const char __user *const __user *argv,
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struct linux_binprm *bprm)
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{
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struct page *kmapped_page = NULL;
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char *kaddr = NULL;
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unsigned long kpos = 0;
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int ret;
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while (argc-- > 0) {
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const char __user *str;
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int len;
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unsigned long pos;
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if (get_user(str, argv+argc) ||
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!(len = strnlen_user(str, MAX_ARG_STRLEN))) {
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ret = -EFAULT;
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goto out;
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}
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if (!valid_arg_len(bprm, len)) {
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ret = -E2BIG;
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goto out;
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}
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|
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/* We're going to work our way backwords. */
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pos = bprm->p;
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str += len;
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bprm->p -= len;
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|
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while (len > 0) {
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int offset, bytes_to_copy;
|
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|
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if (fatal_signal_pending(current)) {
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ret = -ERESTARTNOHAND;
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goto out;
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}
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cond_resched();
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|
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offset = pos % PAGE_SIZE;
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if (offset == 0)
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offset = PAGE_SIZE;
|
|
|
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bytes_to_copy = offset;
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if (bytes_to_copy > len)
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bytes_to_copy = len;
|
|
|
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offset -= bytes_to_copy;
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pos -= bytes_to_copy;
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str -= bytes_to_copy;
|
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len -= bytes_to_copy;
|
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|
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if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
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struct page *page;
|
|
|
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page = get_arg_page(bprm, pos, 1);
|
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if (!page) {
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ret = -E2BIG;
|
|
goto out;
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|
}
|
|
|
|
if (kmapped_page) {
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|
flush_kernel_dcache_page(kmapped_page);
|
|
kunmap(kmapped_page);
|
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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, const char *const *argv,
|
|
struct linux_binprm *bprm)
|
|
{
|
|
int r;
|
|
mm_segment_t oldfs = get_fs();
|
|
set_fs(KERNEL_DS);
|
|
r = copy_strings(argc, (const char __user *const __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)
|
|
*/
|
|
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))
|
|
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. 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;
|
|
|
|
#ifdef CONFIG_STACK_GROWSUP
|
|
/* Limit stack size to 1GB */
|
|
stack_base = rlimit_max(RLIMIT_STACK);
|
|
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);
|
|
|
|
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;
|
|
|
|
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;
|
|
vm_flags |= VM_STACK_INCOMPLETE_SETUP;
|
|
|
|
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)
|
|
goto out_unlock;
|
|
}
|
|
|
|
/* mprotect_fixup is overkill to remove the temporary stack flags */
|
|
vma->vm_flags &= ~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 = rlimit(RLIMIT_STACK) & 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(vma, stack_base);
|
|
if (ret)
|
|
ret = -EFAULT;
|
|
|
|
out_unlock:
|
|
up_write(&mm->mmap_sem);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(setup_arg_pages);
|
|
|
|
#endif /* CONFIG_MMU */
|
|
|
|
struct file *open_exec(const char *name)
|
|
{
|
|
struct file *file;
|
|
int err;
|
|
|
|
file = do_filp_open(AT_FDCWD, name,
|
|
O_LARGEFILE | O_RDONLY | FMODE_EXEC, 0,
|
|
MAY_EXEC | MAY_OPEN);
|
|
if (IS_ERR(file))
|
|
goto out;
|
|
|
|
err = -EACCES;
|
|
if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
|
|
goto exit;
|
|
|
|
if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
|
|
goto exit;
|
|
|
|
fsnotify_open(file);
|
|
|
|
err = deny_write_access(file);
|
|
if (err)
|
|
goto exit;
|
|
|
|
out:
|
|
return file;
|
|
|
|
exit:
|
|
fput(file);
|
|
return ERR_PTR(err);
|
|
}
|
|
EXPORT_SYMBOL(open_exec);
|
|
|
|
int kernel_read(struct file *file, loff_t 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;
|
|
sync_mm_rss(tsk, old_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);
|
|
if (old_mm && tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) {
|
|
atomic_dec(&old_mm->oom_disable_count);
|
|
atomic_inc(&tsk->mm->oom_disable_count);
|
|
}
|
|
task_unlock(tsk);
|
|
arch_pick_mmap_layout(mm);
|
|
if (old_mm) {
|
|
up_read(&old_mm->mmap_sem);
|
|
BUG_ON(active_mm != old_mm);
|
|
mm_update_next_owner(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;
|
|
|
|
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;
|
|
sig->notify_count = zap_other_threads(tsk);
|
|
if (!thread_group_leader(tsk))
|
|
sig->notify_count--;
|
|
|
|
while (sig->notify_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)) {
|
|
struct task_struct *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();
|
|
}
|
|
|
|
/*
|
|
* 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);
|
|
list_replace_init(&leader->sibling, &tsk->sibling);
|
|
|
|
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);
|
|
|
|
release_task(leader);
|
|
}
|
|
|
|
sig->group_exit_task = NULL;
|
|
sig->notify_count = 0;
|
|
|
|
no_thread_group:
|
|
if (current->mm)
|
|
setmax_mm_hiwater_rss(&sig->maxrss, current->mm);
|
|
|
|
exit_itimers(sig);
|
|
flush_itimer_signals();
|
|
|
|
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);
|
|
|
|
/*
|
|
* Threads may access current->comm without holding
|
|
* the task lock, so write the string carefully.
|
|
* Readers without a lock may see incomplete new
|
|
* names but are safe from non-terminating string reads.
|
|
*/
|
|
memset(tsk->comm, 0, TASK_COMM_LEN);
|
|
wmb();
|
|
strlcpy(tsk->comm, buf, sizeof(tsk->comm));
|
|
task_unlock(tsk);
|
|
perf_event_comm(tsk);
|
|
}
|
|
|
|
int flush_old_exec(struct linux_binprm * bprm)
|
|
{
|
|
int retval;
|
|
|
|
/*
|
|
* 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 */
|
|
|
|
current->flags &= ~PF_RANDOMIZE;
|
|
flush_thread();
|
|
current->personality &= ~bprm->per_clear;
|
|
|
|
return 0;
|
|
|
|
out:
|
|
return retval;
|
|
}
|
|
EXPORT_SYMBOL(flush_old_exec);
|
|
|
|
void setup_new_exec(struct linux_binprm * bprm)
|
|
{
|
|
int i, ch;
|
|
const char *name;
|
|
char tcomm[sizeof(current->comm)];
|
|
|
|
arch_pick_mmap_layout(current->mm);
|
|
|
|
/* 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);
|
|
|
|
/* 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;
|
|
|
|
/* install the new credentials */
|
|
if (bprm->cred->uid != current_euid() ||
|
|
bprm->cred->gid != current_egid()) {
|
|
current->pdeath_signal = 0;
|
|
} else if (file_permission(bprm->file, MAY_READ) ||
|
|
bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) {
|
|
set_dumpable(current->mm, suid_dumpable);
|
|
}
|
|
|
|
/*
|
|
* Flush performance counters when crossing a
|
|
* security domain:
|
|
*/
|
|
if (!get_dumpable(current->mm))
|
|
perf_event_exit_task(current);
|
|
|
|
/* 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);
|
|
}
|
|
EXPORT_SYMBOL(setup_new_exec);
|
|
|
|
/*
|
|
* Prepare credentials and lock ->cred_guard_mutex.
|
|
* install_exec_creds() commits the new creds and drops the lock.
|
|
* Or, if exec fails before, free_bprm() should release ->cred and
|
|
* and unlock.
|
|
*/
|
|
int prepare_bprm_creds(struct linux_binprm *bprm)
|
|
{
|
|
if (mutex_lock_interruptible(¤t->cred_guard_mutex))
|
|
return -ERESTARTNOINTR;
|
|
|
|
bprm->cred = prepare_exec_creds();
|
|
if (likely(bprm->cred))
|
|
return 0;
|
|
|
|
mutex_unlock(¤t->cred_guard_mutex);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
void free_bprm(struct linux_binprm *bprm)
|
|
{
|
|
free_arg_pages(bprm);
|
|
if (bprm->cred) {
|
|
mutex_unlock(¤t->cred_guard_mutex);
|
|
abort_creds(bprm->cred);
|
|
}
|
|
kfree(bprm);
|
|
}
|
|
|
|
/*
|
|
* install the new credentials for this executable
|
|
*/
|
|
void install_exec_creds(struct linux_binprm *bprm)
|
|
{
|
|
security_bprm_committing_creds(bprm);
|
|
|
|
commit_creds(bprm->cred);
|
|
bprm->cred = NULL;
|
|
/*
|
|
* 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);
|
|
mutex_unlock(¤t->cred_guard_mutex);
|
|
}
|
|
EXPORT_SYMBOL(install_exec_creds);
|
|
|
|
/*
|
|
* determine how safe it is to execute the proposed program
|
|
* - the caller must hold current->cred_guard_mutex to protect against
|
|
* PTRACE_ATTACH
|
|
*/
|
|
int check_unsafe_exec(struct linux_binprm *bprm)
|
|
{
|
|
struct task_struct *p = current, *t;
|
|
unsigned n_fs;
|
|
int res = 0;
|
|
|
|
bprm->unsafe = tracehook_unsafe_exec(p);
|
|
|
|
n_fs = 1;
|
|
spin_lock(&p->fs->lock);
|
|
rcu_read_lock();
|
|
for (t = next_thread(p); t != p; t = next_thread(t)) {
|
|
if (t->fs == p->fs)
|
|
n_fs++;
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
if (p->fs->users > n_fs) {
|
|
bprm->unsafe |= LSM_UNSAFE_SHARE;
|
|
} else {
|
|
res = -EAGAIN;
|
|
if (!p->fs->in_exec) {
|
|
p->fs->in_exec = 1;
|
|
res = 1;
|
|
}
|
|
}
|
|
spin_unlock(&p->fs->lock);
|
|
|
|
return res;
|
|
}
|
|
|
|
/*
|
|
* Fill the binprm structure from the inode.
|
|
* Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
|
|
*
|
|
* This may be called multiple times for binary chains (scripts for example).
|
|
*/
|
|
int prepare_binprm(struct linux_binprm *bprm)
|
|
{
|
|
umode_t 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;
|
|
|
|
/* clear any previous set[ug]id data from a previous binary */
|
|
bprm->cred->euid = current_euid();
|
|
bprm->cred->egid = current_egid();
|
|
|
|
if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
|
|
/* Set-uid? */
|
|
if (mode & S_ISUID) {
|
|
bprm->per_clear |= PER_CLEAR_ON_SETID;
|
|
bprm->cred->euid = 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)) {
|
|
bprm->per_clear |= PER_CLEAR_ON_SETID;
|
|
bprm->cred->egid = inode->i_gid;
|
|
}
|
|
}
|
|
|
|
/* fill in binprm security blob */
|
|
retval = security_bprm_set_creds(bprm);
|
|
if (retval)
|
|
return retval;
|
|
bprm->cred_prepared = 1;
|
|
|
|
memset(bprm->buf, 0, BINPRM_BUF_SIZE);
|
|
return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
|
|
}
|
|
|
|
EXPORT_SYMBOL(prepare_binprm);
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
unsigned int depth = bprm->recursion_depth;
|
|
int try,retval;
|
|
struct linux_binfmt *fmt;
|
|
|
|
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);
|
|
/*
|
|
* Restore the depth counter to its starting value
|
|
* in this call, so we don't have to rely on every
|
|
* load_binary function to restore it on return.
|
|
*/
|
|
bprm->recursion_depth = depth;
|
|
if (retval >= 0) {
|
|
if (depth == 0)
|
|
tracehook_report_exec(fmt, bprm, regs);
|
|
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_MODULES
|
|
} 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);
|
|
|
|
/*
|
|
* sys_execve() executes a new program.
|
|
*/
|
|
int do_execve(const char * filename,
|
|
const char __user *const __user *argv,
|
|
const char __user *const __user *envp,
|
|
struct pt_regs * regs)
|
|
{
|
|
struct linux_binprm *bprm;
|
|
struct file *file;
|
|
struct files_struct *displaced;
|
|
bool clear_in_exec;
|
|
int retval;
|
|
|
|
retval = unshare_files(&displaced);
|
|
if (retval)
|
|
goto out_ret;
|
|
|
|
retval = -ENOMEM;
|
|
bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
|
|
if (!bprm)
|
|
goto out_files;
|
|
|
|
retval = prepare_bprm_creds(bprm);
|
|
if (retval)
|
|
goto out_free;
|
|
|
|
retval = check_unsafe_exec(bprm);
|
|
if (retval < 0)
|
|
goto out_free;
|
|
clear_in_exec = retval;
|
|
current->in_execve = 1;
|
|
|
|
file = open_exec(filename);
|
|
retval = PTR_ERR(file);
|
|
if (IS_ERR(file))
|
|
goto out_unmark;
|
|
|
|
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;
|
|
|
|
bprm->envc = count(envp, MAX_ARG_STRINGS);
|
|
if ((retval = bprm->envc) < 0)
|
|
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)
|
|
goto out;
|
|
|
|
/* execve succeeded */
|
|
current->fs->in_exec = 0;
|
|
current->in_execve = 0;
|
|
acct_update_integrals(current);
|
|
free_bprm(bprm);
|
|
if (displaced)
|
|
put_files_struct(displaced);
|
|
return retval;
|
|
|
|
out:
|
|
if (bprm->mm)
|
|
mmput (bprm->mm);
|
|
|
|
out_file:
|
|
if (bprm->file) {
|
|
allow_write_access(bprm->file);
|
|
fput(bprm->file);
|
|
}
|
|
|
|
out_unmark:
|
|
if (clear_in_exec)
|
|
current->fs->in_exec = 0;
|
|
current->in_execve = 0;
|
|
|
|
out_free:
|
|
free_bprm(bprm);
|
|
|
|
out_files:
|
|
if (displaced)
|
|
reset_files_struct(displaced);
|
|
out_ret:
|
|
return retval;
|
|
}
|
|
|
|
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);
|
|
|
|
/* 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, long signr)
|
|
{
|
|
const struct cred *cred = current_cred();
|
|
const char *pat_ptr = core_pattern;
|
|
int ispipe = (*pat_ptr == '|');
|
|
char *out_ptr = corename;
|
|
char *const out_end = corename + CORENAME_MAX_SIZE;
|
|
int rc;
|
|
int pid_in_pattern = 0;
|
|
|
|
/* 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", cred->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", cred->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", rlimit(RLIMIT_CORE));
|
|
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) {
|
|
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 int zap_process(struct task_struct *start, int exit_code)
|
|
{
|
|
struct task_struct *t;
|
|
int nr = 0;
|
|
|
|
start->signal->flags = SIGNAL_GROUP_EXIT;
|
|
start->signal->group_exit_code = exit_code;
|
|
start->signal->group_stop_count = 0;
|
|
|
|
t = start;
|
|
do {
|
|
if (t != current && t->mm) {
|
|
sigaddset(&t->pending.signal, SIGKILL);
|
|
signal_wake_up(t, 1);
|
|
nr++;
|
|
}
|
|
} while_each_thread(start, t);
|
|
|
|
return nr;
|
|
}
|
|
|
|
static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
|
|
struct core_state *core_state, int exit_code)
|
|
{
|
|
struct task_struct *g, *p;
|
|
unsigned long flags;
|
|
int nr = -EAGAIN;
|
|
|
|
spin_lock_irq(&tsk->sighand->siglock);
|
|
if (!signal_group_exit(tsk->signal)) {
|
|
mm->core_state = core_state;
|
|
nr = zap_process(tsk, exit_code);
|
|
}
|
|
spin_unlock_irq(&tsk->sighand->siglock);
|
|
if (unlikely(nr < 0))
|
|
return nr;
|
|
|
|
if (atomic_read(&mm->mm_users) == nr + 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);
|
|
nr += zap_process(p, exit_code);
|
|
unlock_task_sighand(p, &flags);
|
|
}
|
|
break;
|
|
}
|
|
} while_each_thread(g, p);
|
|
}
|
|
rcu_read_unlock();
|
|
done:
|
|
atomic_set(&core_state->nr_threads, nr);
|
|
return nr;
|
|
}
|
|
|
|
static int coredump_wait(int exit_code, struct core_state *core_state)
|
|
{
|
|
struct task_struct *tsk = current;
|
|
struct mm_struct *mm = tsk->mm;
|
|
struct completion *vfork_done;
|
|
int core_waiters = -EBUSY;
|
|
|
|
init_completion(&core_state->startup);
|
|
core_state->dumper.task = tsk;
|
|
core_state->dumper.next = NULL;
|
|
|
|
down_write(&mm->mmap_sem);
|
|
if (!mm->core_state)
|
|
core_waiters = zap_threads(tsk, mm, core_state, exit_code);
|
|
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);
|
|
fail:
|
|
return core_waiters;
|
|
}
|
|
|
|
static void coredump_finish(struct mm_struct *mm)
|
|
{
|
|
struct core_thread *curr, *next;
|
|
struct task_struct *task;
|
|
|
|
next = mm->core_state->dumper.next;
|
|
while ((curr = next) != NULL) {
|
|
next = curr->next;
|
|
task = curr->task;
|
|
/*
|
|
* see exit_mm(), curr->task must not see
|
|
* ->task == NULL before we read ->next.
|
|
*/
|
|
smp_mb();
|
|
curr->task = NULL;
|
|
wake_up_process(task);
|
|
}
|
|
|
|
mm->core_state = NULL;
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
}
|
|
}
|
|
|
|
static int __get_dumpable(unsigned long mm_flags)
|
|
{
|
|
int ret;
|
|
|
|
ret = mm_flags & MMF_DUMPABLE_MASK;
|
|
return (ret >= 2) ? 2 : ret;
|
|
}
|
|
|
|
int get_dumpable(struct mm_struct *mm)
|
|
{
|
|
return __get_dumpable(mm->flags);
|
|
}
|
|
|
|
static void wait_for_dump_helpers(struct file *file)
|
|
{
|
|
struct pipe_inode_info *pipe;
|
|
|
|
pipe = file->f_path.dentry->d_inode->i_pipe;
|
|
|
|
pipe_lock(pipe);
|
|
pipe->readers++;
|
|
pipe->writers--;
|
|
|
|
while ((pipe->readers > 1) && (!signal_pending(current))) {
|
|
wake_up_interruptible_sync(&pipe->wait);
|
|
kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
|
|
pipe_wait(pipe);
|
|
}
|
|
|
|
pipe->readers--;
|
|
pipe->writers++;
|
|
pipe_unlock(pipe);
|
|
|
|
}
|
|
|
|
|
|
/*
|
|
* uhm_pipe_setup
|
|
* helper function to customize the process used
|
|
* to collect the core in userspace. Specifically
|
|
* it sets up a pipe and installs it as fd 0 (stdin)
|
|
* for the process. Returns 0 on success, or
|
|
* PTR_ERR on failure.
|
|
* Note that it also sets the core limit to 1. This
|
|
* is a special value that we use to trap recursive
|
|
* core dumps
|
|
*/
|
|
static int umh_pipe_setup(struct subprocess_info *info)
|
|
{
|
|
struct file *rp, *wp;
|
|
struct fdtable *fdt;
|
|
struct coredump_params *cp = (struct coredump_params *)info->data;
|
|
struct files_struct *cf = current->files;
|
|
|
|
wp = create_write_pipe(0);
|
|
if (IS_ERR(wp))
|
|
return PTR_ERR(wp);
|
|
|
|
rp = create_read_pipe(wp, 0);
|
|
if (IS_ERR(rp)) {
|
|
free_write_pipe(wp);
|
|
return PTR_ERR(rp);
|
|
}
|
|
|
|
cp->file = wp;
|
|
|
|
sys_close(0);
|
|
fd_install(0, rp);
|
|
spin_lock(&cf->file_lock);
|
|
fdt = files_fdtable(cf);
|
|
FD_SET(0, fdt->open_fds);
|
|
FD_CLR(0, fdt->close_on_exec);
|
|
spin_unlock(&cf->file_lock);
|
|
|
|
/* and disallow core files too */
|
|
current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
|
|
|
|
return 0;
|
|
}
|
|
|
|
void do_coredump(long signr, int exit_code, struct pt_regs *regs)
|
|
{
|
|
struct core_state core_state;
|
|
char corename[CORENAME_MAX_SIZE + 1];
|
|
struct mm_struct *mm = current->mm;
|
|
struct linux_binfmt * binfmt;
|
|
const struct cred *old_cred;
|
|
struct cred *cred;
|
|
int retval = 0;
|
|
int flag = 0;
|
|
int ispipe;
|
|
static atomic_t core_dump_count = ATOMIC_INIT(0);
|
|
struct coredump_params cprm = {
|
|
.signr = signr,
|
|
.regs = regs,
|
|
.limit = rlimit(RLIMIT_CORE),
|
|
/*
|
|
* We must use the same mm->flags while dumping core to avoid
|
|
* inconsistency of bit flags, since this flag is not protected
|
|
* by any locks.
|
|
*/
|
|
.mm_flags = mm->flags,
|
|
};
|
|
|
|
audit_core_dumps(signr);
|
|
|
|
binfmt = mm->binfmt;
|
|
if (!binfmt || !binfmt->core_dump)
|
|
goto fail;
|
|
if (!__get_dumpable(cprm.mm_flags))
|
|
goto fail;
|
|
|
|
cred = prepare_creds();
|
|
if (!cred)
|
|
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(cprm.mm_flags) == 2) {
|
|
/* Setuid core dump mode */
|
|
flag = O_EXCL; /* Stop rewrite attacks */
|
|
cred->fsuid = 0; /* Dump root private */
|
|
}
|
|
|
|
retval = coredump_wait(exit_code, &core_state);
|
|
if (retval < 0)
|
|
goto fail_creds;
|
|
|
|
old_cred = override_creds(cred);
|
|
|
|
/*
|
|
* 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);
|
|
|
|
ispipe = format_corename(corename, signr);
|
|
|
|
if (ispipe) {
|
|
int dump_count;
|
|
char **helper_argv;
|
|
|
|
if (cprm.limit == 1) {
|
|
/*
|
|
* Normally core limits are irrelevant to pipes, since
|
|
* we're not writing to the file system, but we use
|
|
* cprm.limit of 1 here as a speacial value. Any
|
|
* non-1 limit gets set to RLIM_INFINITY below, but
|
|
* a limit of 0 skips the dump. This is a consistent
|
|
* way to catch recursive crashes. We can still crash
|
|
* if the core_pattern binary sets RLIM_CORE = !1
|
|
* but it runs as root, and can do lots of stupid things
|
|
* Note that we use task_tgid_vnr here to grab the pid
|
|
* of the process group leader. That way we get the
|
|
* right pid if a thread in a multi-threaded
|
|
* core_pattern process dies.
|
|
*/
|
|
printk(KERN_WARNING
|
|
"Process %d(%s) has RLIMIT_CORE set to 1\n",
|
|
task_tgid_vnr(current), current->comm);
|
|
printk(KERN_WARNING "Aborting core\n");
|
|
goto fail_unlock;
|
|
}
|
|
cprm.limit = RLIM_INFINITY;
|
|
|
|
dump_count = atomic_inc_return(&core_dump_count);
|
|
if (core_pipe_limit && (core_pipe_limit < dump_count)) {
|
|
printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
|
|
task_tgid_vnr(current), current->comm);
|
|
printk(KERN_WARNING "Skipping core dump\n");
|
|
goto fail_dropcount;
|
|
}
|
|
|
|
helper_argv = argv_split(GFP_KERNEL, corename+1, NULL);
|
|
if (!helper_argv) {
|
|
printk(KERN_WARNING "%s failed to allocate memory\n",
|
|
__func__);
|
|
goto fail_dropcount;
|
|
}
|
|
|
|
retval = call_usermodehelper_fns(helper_argv[0], helper_argv,
|
|
NULL, UMH_WAIT_EXEC, umh_pipe_setup,
|
|
NULL, &cprm);
|
|
argv_free(helper_argv);
|
|
if (retval) {
|
|
printk(KERN_INFO "Core dump to %s pipe failed\n",
|
|
corename);
|
|
goto close_fail;
|
|
}
|
|
} else {
|
|
struct inode *inode;
|
|
|
|
if (cprm.limit < binfmt->min_coredump)
|
|
goto fail_unlock;
|
|
|
|
cprm.file = filp_open(corename,
|
|
O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
|
|
0600);
|
|
if (IS_ERR(cprm.file))
|
|
goto fail_unlock;
|
|
|
|
inode = cprm.file->f_path.dentry->d_inode;
|
|
if (inode->i_nlink > 1)
|
|
goto close_fail;
|
|
if (d_unhashed(cprm.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 (!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 (!cprm.file->f_op || !cprm.file->f_op->write)
|
|
goto close_fail;
|
|
if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
|
|
goto close_fail;
|
|
}
|
|
|
|
retval = binfmt->core_dump(&cprm);
|
|
if (retval)
|
|
current->signal->group_exit_code |= 0x80;
|
|
|
|
if (ispipe && core_pipe_limit)
|
|
wait_for_dump_helpers(cprm.file);
|
|
close_fail:
|
|
if (cprm.file)
|
|
filp_close(cprm.file, NULL);
|
|
fail_dropcount:
|
|
if (ispipe)
|
|
atomic_dec(&core_dump_count);
|
|
fail_unlock:
|
|
coredump_finish(mm);
|
|
revert_creds(old_cred);
|
|
fail_creds:
|
|
put_cred(cred);
|
|
fail:
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Core dumping helper functions. These are the only things you should
|
|
* do on a core-file: use only these functions to write out all the
|
|
* necessary info.
|
|
*/
|
|
int dump_write(struct file *file, const void *addr, int nr)
|
|
{
|
|
return access_ok(VERIFY_READ, addr, nr) && file->f_op->write(file, addr, nr, &file->f_pos) == nr;
|
|
}
|
|
EXPORT_SYMBOL(dump_write);
|
|
|
|
int dump_seek(struct file *file, loff_t off)
|
|
{
|
|
int ret = 1;
|
|
|
|
if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
|
|
if (file->f_op->llseek(file, off, SEEK_CUR) < 0)
|
|
return 0;
|
|
} else {
|
|
char *buf = (char *)get_zeroed_page(GFP_KERNEL);
|
|
|
|
if (!buf)
|
|
return 0;
|
|
while (off > 0) {
|
|
unsigned long n = off;
|
|
|
|
if (n > PAGE_SIZE)
|
|
n = PAGE_SIZE;
|
|
if (!dump_write(file, buf, n)) {
|
|
ret = 0;
|
|
break;
|
|
}
|
|
off -= n;
|
|
}
|
|
free_page((unsigned long)buf);
|
|
}
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(dump_seek);
|