coredump: move core dump functionality into its own file (10c28d93) · Commits · 戴 / test

fs/Makefile

+1 −1

Original line number	Diff line number	Diff line
		@@ -11,7 +11,7 @@ obj-y := open.o read_write.o file_table.o super.o \
		attr.o bad_inode.o file.o filesystems.o namespace.o \
		seq_file.o xattr.o libfs.o fs-writeback.o \
		pnode.o drop_caches.o splice.o sync.o utimes.o \
		stack.o fs_struct.o statfs.o
		stack.o fs_struct.o statfs.o coredump.o

		ifeq ($(CONFIG_BLOCK),y)
		obj-y += buffer.o bio.o block_dev.o direct-io.o mpage.o ioprio.o

fs/coredump.c

0 → 100644

+686 −0

Original line number	Diff line number	Diff line
		#include <linux/slab.h>
		#include <linux/file.h>
		#include <linux/fdtable.h>
		#include <linux/mm.h>
		#include <linux/stat.h>
		#include <linux/fcntl.h>
		#include <linux/swap.h>
		#include <linux/string.h>
		#include <linux/init.h>
		#include <linux/pagemap.h>
		#include <linux/perf_event.h>
		#include <linux/highmem.h>
		#include <linux/spinlock.h>
		#include <linux/key.h>
		#include <linux/personality.h>
		#include <linux/binfmts.h>
		#include <linux/utsname.h>
		#include <linux/pid_namespace.h>
		#include <linux/module.h>
		#include <linux/namei.h>
		#include <linux/mount.h>
		#include <linux/security.h>
		#include <linux/syscalls.h>
		#include <linux/tsacct_kern.h>
		#include <linux/cn_proc.h>
		#include <linux/audit.h>
		#include <linux/tracehook.h>
		#include <linux/kmod.h>
		#include <linux/fsnotify.h>
		#include <linux/fs_struct.h>
		#include <linux/pipe_fs_i.h>
		#include <linux/oom.h>
		#include <linux/compat.h>

		#include <asm/uaccess.h>
		#include <asm/mmu_context.h>
		#include <asm/tlb.h>
		#include <asm/exec.h>

		#include <trace/events/task.h>
		#include "internal.h"

		#include <trace/events/sched.h>

		int core_uses_pid;
		char core_pattern[CORENAME_MAX_SIZE] = "core";
		unsigned int core_pipe_limit;

		struct core_name {
		char *corename;
		int used, size;
		};
		static atomic_t call_count = ATOMIC_INIT(1);

		/* The maximal length of core_pattern is also specified in sysctl.c */

		static int expand_corename(struct core_name *cn)
		{
		char *old_corename = cn->corename;

		cn->size = CORENAME_MAX_SIZE * atomic_inc_return(&call_count);
		cn->corename = krealloc(old_corename, cn->size, GFP_KERNEL);

		if (!cn->corename) {
		kfree(old_corename);
		return -ENOMEM;
		}

		return 0;
		}

		static int cn_printf(struct core_name cn, const char fmt, ...)
		{
		char *cur;
		int need;
		int ret;
		va_list arg;

		va_start(arg, fmt);
		need = vsnprintf(NULL, 0, fmt, arg);
		va_end(arg);

		if (likely(need < cn->size - cn->used - 1))
		goto out_printf;

		ret = expand_corename(cn);
		if (ret)
		goto expand_fail;

		out_printf:
		cur = cn->corename + cn->used;
		va_start(arg, fmt);
		vsnprintf(cur, need + 1, fmt, arg);
		va_end(arg);
		cn->used += need;
		return 0;

		expand_fail:
		return ret;
		}

		static void cn_escape(char *str)
		{
		for (; *str; str++)
		if (*str == '/')
		*str = '!';
		}

		static int cn_print_exe_file(struct core_name *cn)
		{
		struct file *exe_file;
		char pathbuf, path;
		int ret;

		exe_file = get_mm_exe_file(current->mm);
		if (!exe_file) {
		char *commstart = cn->corename + cn->used;
		ret = cn_printf(cn, "%s (path unknown)", current->comm);
		cn_escape(commstart);
		return ret;
		}

		pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY);
		if (!pathbuf) {
		ret = -ENOMEM;
		goto put_exe_file;
		}

		path = d_path(&exe_file->f_path, pathbuf, PATH_MAX);
		if (IS_ERR(path)) {
		ret = PTR_ERR(path);
		goto free_buf;
		}

		cn_escape(path);

		ret = cn_printf(cn, "%s", path);

		free_buf:
		kfree(pathbuf);
		put_exe_file:
		fput(exe_file);
		return ret;
		}

		/* 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(struct core_name *cn, long signr)
		{
		const struct cred *cred = current_cred();
		const char *pat_ptr = core_pattern;
		int ispipe = (*pat_ptr == '\|');
		int pid_in_pattern = 0;
		int err = 0;

		cn->size = CORENAME_MAX_SIZE * atomic_read(&call_count);
		cn->corename = kmalloc(cn->size, GFP_KERNEL);
		cn->used = 0;

		if (!cn->corename)
		return -ENOMEM;

		/* Repeat as long as we have more pattern to process and more output
		space */
		while (*pat_ptr) {
		if (*pat_ptr != '%') {
		if (*pat_ptr == 0)
		goto out;
		err = cn_printf(cn, "%c", *pat_ptr++);
		} else {
		switch (*++pat_ptr) {
		/* single % at the end, drop that */
		case 0:
		goto out;
		/* Double percent, output one percent */
		case '%':
		err = cn_printf(cn, "%c", '%');
		break;
		/* pid */
		case 'p':
		pid_in_pattern = 1;
		err = cn_printf(cn, "%d",
		task_tgid_vnr(current));
		break;
		/* uid */
		case 'u':
		err = cn_printf(cn, "%d", cred->uid);
		break;
		/* gid */
		case 'g':
		err = cn_printf(cn, "%d", cred->gid);
		break;
		/* signal that caused the coredump */
		case 's':
		err = cn_printf(cn, "%ld", signr);
		break;
		/* UNIX time of coredump */
		case 't': {
		struct timeval tv;
		do_gettimeofday(&tv);
		err = cn_printf(cn, "%lu", tv.tv_sec);
		break;
		}
		/* hostname */
		case 'h': {
		char *namestart = cn->corename + cn->used;
		down_read(&uts_sem);
		err = cn_printf(cn, "%s",
		utsname()->nodename);
		up_read(&uts_sem);
		cn_escape(namestart);
		break;
		}
		/* executable */
		case 'e': {
		char *commstart = cn->corename + cn->used;
		err = cn_printf(cn, "%s", current->comm);
		cn_escape(commstart);
		break;
		}
		case 'E':
		err = cn_print_exe_file(cn);
		break;
		/* core limit size */
		case 'c':
		err = cn_printf(cn, "%lu",
		rlimit(RLIMIT_CORE));
		break;
		default:
		break;
		}
		++pat_ptr;
		}

		if (err)
		return err;
		}

		/* 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) {
		err = cn_printf(cn, ".%d", task_tgid_vnr(current));
		if (err)
		return err;
		}
		out:
		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 {
		task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
		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, &current->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;
		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 (core_waiters > 0) {
		struct core_thread *ptr;

		wait_for_completion(&core_state->startup);
		/*
		* Wait for all the threads to become inactive, so that
		* all the thread context (extended register state, like
		* fpu etc) gets copied to the memory.
		*/
		ptr = core_state->dumper.next;
		while (ptr != NULL) {
		wait_task_inactive(ptr->task, 0);
		ptr = ptr->next;
		}
		}

		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;
		}

		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);

		}

		/*
		* umh_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 cred new)
		{
		struct file *files[2];
		struct coredump_params cp = (struct coredump_params )info->data;
		int err = create_pipe_files(files, 0);
		if (err)
		return err;

		cp->file = files[1];

		replace_fd(0, files[0], 0);
		/* 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;
		struct core_name cn;
		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;
		struct files_struct *displaced;
		bool need_nonrelative = false;
		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, and only into a controlled
		* environment (pipe handler or fully qualified path).
		*/
		if (__get_dumpable(cprm.mm_flags) == SUID_DUMPABLE_SAFE) {
		/* Setuid core dump mode */
		flag = O_EXCL; /* Stop rewrite attacks */
		cred->fsuid = GLOBAL_ROOT_UID; /* Dump root private */
		need_nonrelative = true;
		}

		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(&cn, signr);

		if (ispipe) {
		int dump_count;
		char **helper_argv;

		if (ispipe < 0) {
		printk(KERN_WARNING "format_corename failed\n");
		printk(KERN_WARNING "Aborting core\n");
		goto fail_corename;
		}

		if (cprm.limit == 1) {
		/* See umh_pipe_setup() which sets RLIMIT_CORE = 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, 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, cn.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",
		cn.corename);
		goto close_fail;
		}
		} else {
		struct inode *inode;

		if (cprm.limit < binfmt->min_coredump)
		goto fail_unlock;

		if (need_nonrelative && cn.corename[0] != '/') {
		printk(KERN_WARNING "Pid %d(%s) can only dump core "\
		"to fully qualified path!\n",
		task_tgid_vnr(current), current->comm);
		printk(KERN_WARNING "Skipping core dump\n");
		goto fail_unlock;
		}

		cprm.file = filp_open(cn.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 (!uid_eq(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;
		}

		/* get us an unshared descriptor table; almost always a no-op */
		retval = unshare_files(&displaced);
		if (retval)
		goto close_fail;
		if (displaced)
		put_files_struct(displaced);
		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:
		kfree(cn.corename);
		fail_corename:
		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);

fs/exec.c

+1 −644

File changed.

Preview size limit exceeded, changes collapsed.

include/linux/sched.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -405,6 +405,7 @@ static inline void arch_pick_mmap_layout(struct mm_struct *mm) {}

		extern void set_dumpable(struct mm_struct *mm, int value);
		extern int get_dumpable(struct mm_struct *mm);
		extern int __get_dumpable(unsigned long mm_flags);

		/* get/set_dumpable() values */
		#define SUID_DUMPABLE_DISABLED 0

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