proc_lookupfd_common(): don't bother with instantiate unless the file is open (1ae9bd8b) · Commits · 戴 / test

fs/proc/fd.c

+34 −29

Original line number	Original line	Diff line number	Diff line
	@@ -81,12 +81,29 @@ static const struct file_operations proc_fdinfo_file_operations = {
	.release = single_release,		.release = single_release,
	};		};

			static bool tid_fd_mode(struct task_struct task, unsigned fd, fmode_t mode)
			{
			struct files_struct *files = get_files_struct(task);
			struct file *file;

			if (!files)
			return false;

			rcu_read_lock();
			file = fcheck_files(files, fd);
			if (file)
			*mode = file->f_mode;
			rcu_read_unlock();
			put_files_struct(files);
			return !!file;
			}

	static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)		static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
	{		{
	struct files_struct *files;
	struct task_struct *task;		struct task_struct *task;
	struct inode *inode;		struct inode *inode;
	unsigned int fd;		unsigned int fd;
			fmode_t f_mode;

	if (flags & LOOKUP_RCU)		if (flags & LOOKUP_RCU)
	return -ECHILD;		return -ECHILD;
	@@ -96,18 +113,7 @@ static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
	fd = proc_fd(inode);		fd = proc_fd(inode);

	if (task) {		if (task) {
	files = get_files_struct(task);		if (tid_fd_mode(task, fd, &f_mode)) {
	if (files) {
	struct file *file;

	rcu_read_lock();
	file = fcheck_files(files, fd);
	if (file) {
	unsigned f_mode = file->f_mode;

	rcu_read_unlock();
	put_files_struct(files);

	task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);		task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);

	if (S_ISLNK(inode->i_mode)) {		if (S_ISLNK(inode->i_mode)) {
	@@ -118,14 +124,10 @@ static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
	i_mode \|= S_IWUSR \| S_IXUSR;		i_mode \|= S_IWUSR \| S_IXUSR;
	inode->i_mode = i_mode;		inode->i_mode = i_mode;
	}		}

	security_task_to_inode(task, inode);		security_task_to_inode(task, inode);
	put_task_struct(task);		put_task_struct(task);
	return 1;		return 1;
	}		}
	rcu_read_unlock();
	put_files_struct(files);
	}
	put_task_struct(task);		put_task_struct(task);
	}		}
	return 0;		return 0;
	@@ -203,11 +205,14 @@ static struct dentry proc_lookupfd_common(struct inode dir,
	struct task_struct *task = get_proc_task(dir);		struct task_struct *task = get_proc_task(dir);
	int result = -ENOENT;		int result = -ENOENT;
	unsigned fd = name_to_int(&dentry->d_name);		unsigned fd = name_to_int(&dentry->d_name);
			fmode_t f_mode;

	if (!task)		if (!task)
	goto out_no_task;		goto out_no_task;
	if (fd == ~0U)		if (fd == ~0U)
	goto out;		goto out;
			if (!tid_fd_mode(task, fd, &f_mode))
			goto out;

	result = instantiate(dir, dentry, task, (void *)(unsigned long)fd);		result = instantiate(dir, dentry, task, (void *)(unsigned long)fd);
	out:		out:

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