/* getroot.c: get the root dentry for an NFS mount
*
* Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/time.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/errno.h>
#include <linux/unistd.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/stats.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_mount.h>
#include <linux/nfs4_mount.h>
#include <linux/lockd/bind.h>
#include <linux/seq_file.h>
#include <linux/mount.h>
#include <linux/nfs_idmap.h>
#include <linux/vfs.h>
#include <linux/namei.h>
#include <linux/mnt_namespace.h>
#include <linux/security.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include "nfs4_fs.h"
#include "delegation.h"
#include "internal.h"
#define NFSDBG_FACILITY NFSDBG_CLIENT
/*
* Set the superblock root dentry.
* Note that this function frees the inode in case of error.
*/
static int nfs_superblock_set_dummy_root(struct super_block *sb, struct inode *inode)
{
/* The mntroot acts as the dummy root dentry for this superblock */
if (sb->s_root == NULL) {
sb->s_root = d_alloc_root(inode);
if (sb->s_root == NULL) {
iput(inode);
return -ENOMEM;
}
/* Circumvent igrab(): we know the inode is not being freed */
atomic_inc(&inode->i_count);
/*
* Ensure that this dentry is invisible to d_find_alias().
* Otherwise, it may be spliced into the tree by
* d_materialise_unique if a parent directory from the same
* filesystem gets mounted at a later time.
* This again causes shrink_dcache_for_umount_subtree() to
* Oops, since the test for IS_ROOT() will fail.
*/
spin_lock(&dcache_lock);
list_del_init(&sb->s_root->d_alias);
spin_unlock(&dcache_lock);
}
return 0;
}
/*
* get an NFS2/NFS3 root dentry from the root filehandle
*/
struct dentry *nfs_get_root(struct super_block *sb, struct nfs_fh *mntfh)
{
struct nfs_server *server = NFS_SB(sb);
struct nfs_fsinfo fsinfo;
struct nfs_fattr fattr;
struct dentry *mntroot;
struct inode *inode;
int error;
/* get the actual root for this mount */
fsinfo.fattr = &fattr;
error = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo);
if (error < 0) {
dprintk("nfs_get_root: getattr error = %d\n", -error);
return ERR_PTR(error);
}
inode = nfs_fhget(sb, mntfh, fsinfo.fattr);
if (IS_ERR(inode)) {
dprintk("nfs_get_root: get root inode failed\n");
return ERR_CAST(inode);
}
error = nfs_superblock_set_dummy_root(sb, inode);
if (error != 0)
return ERR_PTR(error);
/* root dentries normally start off anonymous and get spliced in later
* if the dentry tree reaches them; however if the dentry already
* exists, we'll pick it up at this point and use it as the root
*/
mntroot = d_obtain_alias(inode);
if (IS_ERR(mntroot)) {
dprintk("nfs_get_root: get root dentry failed\n");
return mntroot;
}
security_d_instantiate(mntroot, inode);
if (!mntroot->d_op)
mntroot->d_op = server->nfs_client->rpc_ops->dentry_ops;
return mntroot;
}
#ifdef CONFIG_NFS_V4
/*
* Do a simple pathwalk from the root FH of the server to the nominated target
* of the mountpoint
* - give error on symlinks
* - give error on ".." occurring in the path
* - follow traversals
*/
int nfs4_path_walk(struct nfs_server *server,
struct nfs_fh *mntfh,
const char *path)
{
struct nfs_fsinfo fsinfo;
struct nfs_fattr fattr;
struct nfs_fh lastfh;
struct qstr name;
int ret;
dprintk("--> nfs4_path_walk(,,%s)\n", path);
fsinfo.fattr = &fattr;
nfs_fattr_init(&fattr);
/* Eat leading slashes */
while (*path == '/')
path++;
/* Start by getting the root filehandle from the server */
ret = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo);
if (ret < 0) {
dprintk("nfs4_get_root: getroot error = %d\n", -ret);
return ret;
}
if (!S_ISDIR(fattr.mode)) {
printk(KERN_ERR "nfs4_get_root:"
" getroot encountered non-directory\n");
return -ENOTDIR;
}
/* FIXME: It is quite valid for the server to return a referral here */
if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL) {
printk(KERN_ERR "nfs4_get_root:"
" getroot obtained referral\n");
return -EREMOTE;
}
next_component:
dprintk("Next: %s\n", path);
/* extract the next bit of the path */
if (!*path)
goto path_walk_complete;
name.name = path;
while (*path && *path != '/')
path++;
name.len = path - (const char *) name.name;
if (name.len > NFS4_MAXNAMLEN)
return -ENAMETOOLONG;
eat_dot_dir:
while (*path == '/')
path++;
if (path[0] == '.' && (path[1] == '/' || !path[1])) {
path += 2;
goto eat_dot_dir;
}
/* FIXME: Why shouldn't the user be able to use ".." in the path? */
if (path[0] == '.' && path[1] == '.' && (path[2] == '/' || !path[2])
) {
printk(KERN_ERR "nfs4_get_root:"
" Mount path contains reference to \"..\"\n");
return -EINVAL;
}
/* lookup the next FH in the sequence */
memcpy(&lastfh, mntfh, sizeof(lastfh));
dprintk("LookupFH: %*.*s [%s]\n", name.len, name.len, name.name, path);
ret = server->nfs_client->rpc_ops->lookupfh(server, &lastfh, &name,
mntfh, &fattr);
if (ret < 0) {
dprintk("nfs4_get_root: getroot error = %d\n", -ret);
return ret;
}
if (!S_ISDIR(fattr.mode)) {
printk(KERN_ERR "nfs4_get_root:"
" lookupfh encountered non-directory\n");
return -ENOTDIR;
}
/* FIXME: Referrals are quite valid here too */
if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL) {
printk(KERN_ERR "nfs4_get_root:"
" lookupfh obtained referral\n");
return -EREMOTE;
}
goto next_component;
path_walk_complete:
memcpy(&server->fsid, &fattr.fsid, sizeof(server->fsid));
dprintk("<-- nfs4_path_walk() = 0\n");
return 0;
}
/*
* get an NFS4 root dentry from the root filehandle
*/
struct dentry *nfs4_get_root(struct super_block *sb, struct nfs_fh *mntfh)
{
struct nfs_server *server = NFS_SB(sb);
struct nfs_fattr fattr;
struct dentry *mntroot;
struct inode *inode;
int error;
dprintk("--> nfs4_get_root()\n");
/* get the info about the server and filesystem */
error = nfs4_server_capabilities(server, mntfh);
if (error < 0) {
dprintk("nfs_get_root: getcaps error = %d\n",
-error);
return ERR_PTR(error);
}
/* get the actual root for this mount */
error = server->nfs_client->rpc_ops->getattr(server, mntfh, &fattr);
if (error < 0) {
dprintk("nfs_get_root: getattr error = %d\n", -error);
return ERR_PTR(error);
}
inode = nfs_fhget(sb, mntfh, &fattr);
if (IS_ERR(inode)) {
dprintk("nfs_get_root: get root inode failed\n");
return ERR_CAST(inode);
}
error = nfs_superblock_set_dummy_root(sb, inode);
if (error != 0)
return ERR_PTR(error);
/* root dentries normally start off anonymous and get spliced in later
* if the dentry tree reaches them; however if the dentry already
* exists, we'll pick it up at this point and use it as the root
*/
mntroot = d_obtain_alias(inode);
if (IS_ERR(mntroot)) {
dprintk("nfs_get_root: get root dentry failed\n");
return mntroot;
}
security_d_instantiate(mntroot, inode);
if (!mntroot->d_op)
mntroot->d_op = server->nfs_client->rpc_ops->dentry_ops;
dprintk("<-- nfs4_get_root()\n");
return mntroot;
}
#endif /* CONFIG_NFS_V4 */
