Esempio n. 1
0
static struct dentry *proc_ns_dir_lookup(struct inode *dir,
				struct dentry *dentry, unsigned int flags)
{
	struct dentry *error;
	struct task_struct *task = get_proc_task(dir);
	const struct proc_ns_operations **entry, **last;
	unsigned int len = dentry->d_name.len;

	error = ERR_PTR(-ENOENT);

	if (!task)
		goto out_no_task;

	error = ERR_PTR(-EPERM);
	if (!ptrace_may_access(task, PTRACE_MODE_READ))
		goto out;

	last = &ns_entries[ARRAY_SIZE(ns_entries)];
	for (entry = ns_entries; entry < last; entry++) {
		if (strlen((*entry)->name) != len)
			continue;
		if (!memcmp(dentry->d_name.name, (*entry)->name, len))
			break;
	}
	error = ERR_PTR(-ENOENT);
	if (entry == last)
		goto out;

	error = proc_ns_instantiate(dir, dentry, task, *entry);
out:
	put_task_struct(task);
out_no_task:
	return error;
}
static struct dentry *proc_ns_get_dentry(struct super_block *sb,
	struct task_struct *task, const struct proc_ns_operations *ns_ops)
{
	struct dentry *dentry, *result;
	struct inode *inode;
	struct proc_inode *ei;
	struct qstr qname = { .name = "", };
	void *ns;

	ns = ns_ops->get(task);
	if (!ns)
		return ERR_PTR(-ENOENT);

	dentry = d_alloc_pseudo(sb, &qname);
	if (!dentry) {
		ns_ops->put(ns);
		return ERR_PTR(-ENOMEM);
	}

	inode = iget_locked(sb, ns_ops->inum(ns));
	if (!inode) {
		dput(dentry);
		ns_ops->put(ns);
		return ERR_PTR(-ENOMEM);
	}

	ei = PROC_I(inode);
	if (inode->i_state & I_NEW) {
		inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
		inode->i_op = &ns_inode_operations;
		inode->i_mode = S_IFREG | S_IRUGO;
		inode->i_fop = &ns_file_operations;
		ei->ns.ns_ops = ns_ops;
		ei->ns.ns = ns;
		unlock_new_inode(inode);
	} else {
		ns_ops->put(ns);
	}

	d_set_d_op(dentry, &ns_dentry_operations);
	result = d_instantiate_unique(dentry, inode);
	if (result) {
		dput(dentry);
		dentry = result;
	}

	return dentry;
}

static void *proc_ns_follow_link(struct dentry *dentry, struct nameidata *nd)
{
	struct inode *inode = dentry->d_inode;
	struct super_block *sb = inode->i_sb;
	struct proc_inode *ei = PROC_I(inode);
	struct task_struct *task;
	struct path ns_path;
	void *error = ERR_PTR(-EACCES);

	task = get_proc_task(inode);
	if (!task)
		goto out;

	if (!ptrace_may_access(task, PTRACE_MODE_READ))
		goto out_put_task;

	ns_path.dentry = proc_ns_get_dentry(sb, task, ei->ns.ns_ops);
	if (IS_ERR(ns_path.dentry)) {
		error = ERR_CAST(ns_path.dentry);
		goto out_put_task;
	}

	ns_path.mnt = mntget(nd->path.mnt);
	nd_jump_link(nd, &ns_path);
	error = NULL;

out_put_task:
	put_task_struct(task);
out:
	return error;
}

static int proc_ns_readlink(struct dentry *dentry, char __user *buffer, int buflen)
{
	struct inode *inode = dentry->d_inode;
	struct proc_inode *ei = PROC_I(inode);
	const struct proc_ns_operations *ns_ops = ei->ns.ns_ops;
	struct task_struct *task;
	void *ns;
	char name[50];
	int len = -EACCES;

	task = get_proc_task(inode);
	if (!task)
		goto out;

	if (!ptrace_may_access(task, PTRACE_MODE_READ))
		goto out_put_task;

	len = -ENOENT;
	ns = ns_ops->get(task);
	if (!ns)
		goto out_put_task;

	snprintf(name, sizeof(name), "%s:[%u]", ns_ops->name, ns_ops->inum(ns));
	len = strlen(name);

	if (len > buflen)
		len = buflen;
	if (copy_to_user(buffer, name, len))
		len = -EFAULT;

	ns_ops->put(ns);
out_put_task:
	put_task_struct(task);
out:
	return len;
}

static const struct inode_operations proc_ns_link_inode_operations = {
	.readlink	= proc_ns_readlink,
	.follow_link	= proc_ns_follow_link,
	.setattr	= proc_setattr,
};

static int proc_ns_instantiate(struct inode *dir,
	struct dentry *dentry, struct task_struct *task, const void *ptr)
{
	const struct proc_ns_operations *ns_ops = ptr;
	struct inode *inode;
	struct proc_inode *ei;

	inode = proc_pid_make_inode(dir->i_sb, task);
	if (!inode)
		goto out;

	ei = PROC_I(inode);
	inode->i_mode = S_IFLNK|S_IRWXUGO;
	inode->i_op = &proc_ns_link_inode_operations;
	ei->ns.ns_ops = ns_ops;

	d_set_d_op(dentry, &pid_dentry_operations);
	d_add(dentry, inode);
	/* Close the race of the process dying before we return the dentry */
	if (pid_revalidate(dentry, 0))
		return 0;
out:
	return -ENOENT;
}

static int proc_ns_dir_readdir(struct file *file, struct dir_context *ctx)
{
	struct task_struct *task = get_proc_task(file_inode(file));
	const struct proc_ns_operations **entry, **last;

	if (!task)
		return -ENOENT;

	if (!dir_emit_dots(file, ctx))
		goto out;
	if (ctx->pos >= 2 + ARRAY_SIZE(ns_entries))
		goto out;
	entry = ns_entries + (ctx->pos - 2);
	last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
	while (entry <= last) {
		const struct proc_ns_operations *ops = *entry;
		if (!proc_fill_cache(file, ctx, ops->name, strlen(ops->name),
				     proc_ns_instantiate, task, ops))
			break;
		ctx->pos++;
		entry++;
	}
out:
	put_task_struct(task);
	return 0;
}

const struct file_operations proc_ns_dir_operations = {
	.read		= generic_read_dir,
	.iterate	= proc_ns_dir_readdir,
};

static struct dentry *proc_ns_dir_lookup(struct inode *dir,
				struct dentry *dentry, unsigned int flags)
{
	int error;
	struct task_struct *task = get_proc_task(dir);
	const struct proc_ns_operations **entry, **last;
	unsigned int len = dentry->d_name.len;

	error = -ENOENT;

	if (!task)
		goto out_no_task;

	last = &ns_entries[ARRAY_SIZE(ns_entries)];
	for (entry = ns_entries; entry < last; entry++) {
		if (strlen((*entry)->name) != len)
			continue;
		if (!memcmp(dentry->d_name.name, (*entry)->name, len))
			break;
	}
	if (entry == last)
		goto out;

	error = proc_ns_instantiate(dir, dentry, task, *entry);
out:
	put_task_struct(task);
out_no_task:
	return ERR_PTR(error);
}