fs/nfs/getroot.c - kernel/prism - Git at Google

 /* 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/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 */
	/* 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/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 */