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Commit 5d1baf3b authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

exec: introduce exec_binprm() for "depth == 0" code 



task_pid_nr_ns() and trace/ptrace code in the middle of the recursive
search_binary_handler() looks confusing and imho annoying.  We only need
this code if "depth == 0", lets add a simple helper which calls
search_binary_handler() and does trace_sched_process_exec() +
ptrace_event().

The patch also moves the setting of task->did_exec, we need to do this
only once.

Note: we can kill either task->did_exec or PF_FORKNOEXEC.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarKees Cook <keescook@chromium.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Evgeniy Polyakov <zbr@ioremap.net>
Cc: Zach Levis <zml@linux.vnet.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 96d0df79

fs/exec.c

+22 −14
Original line number Diff line number Diff line
@@ -1373,7 +1373,6 @@ int search_binary_handler(struct linux_binprm *bprm) 
	unsigned int depth = bprm->recursion_depth;

	int try,retval;

	struct linux_binfmt *fmt;

	pid_t old_pid, old_vpid;



	/* This allows 4 levels of binfmt rewrites before failing hard. */

	if (depth > 5)
@@ -1387,12 +1386,6 @@ int search_binary_handler(struct linux_binprm *bprm) 
	if (retval)

		return retval;



	/* Need to fetch pid before load_binary changes it */

	old_pid = current->pid;

	rcu_read_lock();

	old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));

	rcu_read_unlock();



	retval = -ENOENT;

	for (try=0; try<2; try++) {

		read_lock(&binfmt_lock);
@@ -1407,16 +1400,11 @@ int search_binary_handler(struct linux_binprm *bprm) 
			retval = fn(bprm);

			bprm->recursion_depth = depth;

			if (retval >= 0) {

				if (depth == 0) {

					trace_sched_process_exec(current, old_pid, bprm);

					ptrace_event(PTRACE_EVENT_EXEC, old_vpid);

				}

				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;

			}
@@ -1450,9 +1438,29 @@ int search_binary_handler(struct linux_binprm *bprm) 
	}

	return retval;

}



EXPORT_SYMBOL(search_binary_handler);



static int exec_binprm(struct linux_binprm *bprm)

{

	pid_t old_pid, old_vpid;

	int ret;



	/* Need to fetch pid before load_binary changes it */

	old_pid = current->pid;

	rcu_read_lock();

	old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));

	rcu_read_unlock();



	ret = search_binary_handler(bprm);

	if (ret >= 0) {

		trace_sched_process_exec(current, old_pid, bprm);

		ptrace_event(PTRACE_EVENT_EXEC, old_vpid);

		current->did_exec = 1;

	}



	return ret;

}



/*

 * sys_execve() executes a new program.

 */
@@ -1541,7 +1549,7 @@ static int do_execve_common(const char *filename, 
	if (retval < 0)

		goto out;



	retval = search_binary_handler(bprm);

	retval = exec_binprm(bprm);

	if (retval < 0)

		goto out;