/*
   * linux/fs/nfs/nfs4namespace.c
   *
   * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
   * - Modified by David Howells <dhowells@redhat.com>
   *
   * NFSv4 namespace
   */
  
  #include <linux/dcache.h>
  #include <linux/mount.h>
  #include <linux/namei.h>
  #include <linux/nfs_fs.h>
  #include <linux/nfs_mount.h>
  #include <linux/slab.h>
  #include <linux/string.h>
  #include <linux/sunrpc/clnt.h>
  #include <linux/sunrpc/addr.h>
  #include <linux/vfs.h>
  #include <linux/inet.h>
  #include "internal.h"
  #include "nfs4_fs.h"
  #include "dns_resolve.h"
  
  #define NFSDBG_FACILITY		NFSDBG_VFS
  
  /*
   * Convert the NFSv4 pathname components into a standard posix path.
   *
   * Note that the resulting string will be placed at the end of the buffer
   */
  static inline char *nfs4_pathname_string(const struct nfs4_pathname *pathname,
  					 char *buffer, ssize_t buflen)
  {
  	char *end = buffer + buflen;
  	int n;
  
  	*--end = '\0';
  	buflen--;
  
  	n = pathname->ncomponents;
  	while (--n >= 0) {
  		const struct nfs4_string *component = &pathname->components[n];
  		buflen -= component->len + 1;
  		if (buflen < 0)
  			goto Elong;
  		end -= component->len;
  		memcpy(end, component->data, component->len);
  		*--end = '/';
  	}
  	return end;
  Elong:
  	return ERR_PTR(-ENAMETOOLONG);
  }
  
  /*
   * return the path component of "<server>:<path>"
   *  nfspath - the "<server>:<path>" string
   *  end - one past the last char that could contain "<server>:"
   * returns NULL on failure
   */
  static char *nfs_path_component(const char *nfspath, const char *end)
  {
  	char *p;
  
  	if (*nfspath == '[') {
  		/* parse [] escaped IPv6 addrs */
  		p = strchr(nfspath, ']');
  		if (p != NULL && ++p < end && *p == ':')
  			return p + 1;
  	} else {
  		/* otherwise split on first colon */
  		p = strchr(nfspath, ':');
  		if (p != NULL && p < end)
  			return p + 1;
  	}
  	return NULL;
  }
  
  /*
   * Determine the mount path as a string
   */
  static char *nfs4_path(struct dentry *dentry, char *buffer, ssize_t buflen)
  {
  	char *limit;
  	char *path = nfs_path(&limit, dentry, buffer, buflen,
  			      NFS_PATH_CANONICAL);
  	if (!IS_ERR(path)) {
  		char *path_component = nfs_path_component(path, limit);
  		if (path_component)
  			return path_component;
  	}
  	return path;
  }
  
  /*
   * Check that fs_locations::fs_root [RFC3530 6.3] is a prefix for what we
   * believe to be the server path to this dentry
   */
  static int nfs4_validate_fspath(struct dentry *dentry,
  				const struct nfs4_fs_locations *locations,
  				char *page, char *page2)
  {
  	const char *path, *fs_path;
  
  	path = nfs4_path(dentry, page, PAGE_SIZE);
  	if (IS_ERR(path))
  		return PTR_ERR(path);
  
  	fs_path = nfs4_pathname_string(&locations->fs_path, page2, PAGE_SIZE);
  	if (IS_ERR(fs_path))
  		return PTR_ERR(fs_path);
  
  	if (strncmp(path, fs_path, strlen(fs_path)) != 0) {
  		dprintk("%s: path %s does not begin with fsroot %s
  ",
  			__func__, path, fs_path);
  		return -ENOENT;
  	}
  
  	return 0;
  }
  
  static size_t nfs_parse_server_name(char *string, size_t len,
  		struct sockaddr *sa, size_t salen, struct net *net)
  {
  	ssize_t ret;
  
  	ret = rpc_pton(net, string, len, sa, salen);
  	if (ret == 0) {
  		ret = nfs_dns_resolve_name(net, string, len, sa, salen);
  		if (ret < 0)
  			ret = 0;
  	}
  	return ret;
  }
  
  /**
   * nfs_find_best_sec - Find a security mechanism supported locally
   * @server: NFS server struct
   * @flavors: List of security tuples returned by SECINFO procedure
   *
   * Return the pseudoflavor of the first security mechanism in
   * "flavors" that is locally supported.  Return RPC_AUTH_UNIX if
   * no matching flavor is found in the array.  The "flavors" array
   * is searched in the order returned from the server, per RFC 3530
   * recommendation.
   */
  static rpc_authflavor_t nfs_find_best_sec(struct nfs_server *server,
  					  struct nfs4_secinfo_flavors *flavors)
  {
  	rpc_authflavor_t pseudoflavor;
  	struct nfs4_secinfo4 *secinfo;
  	unsigned int i;
  
  	for (i = 0; i < flavors->num_flavors; i++) {
  		secinfo = &flavors->flavors[i];
  
  		switch (secinfo->flavor) {
  		case RPC_AUTH_NULL:
  		case RPC_AUTH_UNIX:
  		case RPC_AUTH_GSS:
  			pseudoflavor = rpcauth_get_pseudoflavor(secinfo->flavor,
  							&secinfo->flavor_info);
  			/* make sure pseudoflavor matches sec= mount opt */
  			if (pseudoflavor != RPC_AUTH_MAXFLAVOR &&
  			    nfs_auth_info_match(&server->auth_info,
  						pseudoflavor))
  				return pseudoflavor;
  			break;
  		}
  	}
  
  	/* if there were any sec= options then nothing matched */
  	if (server->auth_info.flavor_len > 0)
  		return -EPERM;
  
  	return RPC_AUTH_UNIX;
  }
  
  static rpc_authflavor_t nfs4_negotiate_security(struct inode *inode, struct qstr *name)
  {
  	struct page *page;
  	struct nfs4_secinfo_flavors *flavors;
  	rpc_authflavor_t flavor;
  	int err;
  
  	page = alloc_page(GFP_KERNEL);
  	if (!page)
  		return -ENOMEM;
  	flavors = page_address(page);
  
  	err = nfs4_proc_secinfo(inode, name, flavors);
  	if (err < 0) {
  		flavor = err;
  		goto out;
  	}
  
  	flavor = nfs_find_best_sec(NFS_SERVER(inode), flavors);
  
  out:
  	put_page(page);
  	return flavor;
  }
  
  /*
   * Please call rpc_shutdown_client() when you are done with this client.
   */
  struct rpc_clnt *nfs4_create_sec_client(struct rpc_clnt *clnt, struct inode *inode,
  					struct qstr *name)
  {
  	rpc_authflavor_t flavor;
  
  	flavor = nfs4_negotiate_security(inode, name);
  	if ((int)flavor < 0)
  		return ERR_PTR((int)flavor);
  
  	return rpc_clone_client_set_auth(clnt, flavor);
  }
  
  static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
  				     char *page, char *page2,
  				     const struct nfs4_fs_location *location)
  {
  	const size_t addr_bufsize = sizeof(struct sockaddr_storage);
  	struct net *net = rpc_net_ns(NFS_SB(mountdata->sb)->client);
  	struct vfsmount *mnt = ERR_PTR(-ENOENT);
  	char *mnt_path;
  	unsigned int maxbuflen;
  	unsigned int s;
  
  	mnt_path = nfs4_pathname_string(&location->rootpath, page2, PAGE_SIZE);
  	if (IS_ERR(mnt_path))
  		return ERR_CAST(mnt_path);
  	mountdata->mnt_path = mnt_path;
  	maxbuflen = mnt_path - 1 - page2;
  
  	mountdata->addr = kmalloc(addr_bufsize, GFP_KERNEL);
  	if (mountdata->addr == NULL)
  		return ERR_PTR(-ENOMEM);
  
  	for (s = 0; s < location->nservers; s++) {
  		const struct nfs4_string *buf = &location->servers[s];
  
  		if (buf->len <= 0 || buf->len >= maxbuflen)
  			continue;
  
  		if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
  			continue;
  
  		mountdata->addrlen = nfs_parse_server_name(buf->data, buf->len,
  				mountdata->addr, addr_bufsize, net);
  		if (mountdata->addrlen == 0)
  			continue;
  
  		rpc_set_port(mountdata->addr, NFS_PORT);
  
  		memcpy(page2, buf->data, buf->len);
  		page2[buf->len] = '\0';
  		mountdata->hostname = page2;
  
  		snprintf(page, PAGE_SIZE, "%s:%s",
  				mountdata->hostname,
  				mountdata->mnt_path);
  
  		mnt = vfs_kern_mount(&nfs4_referral_fs_type, 0, page, mountdata);
  		if (!IS_ERR(mnt))
  			break;
  	}
  	kfree(mountdata->addr);
  	return mnt;
  }
  
  /**
   * nfs_follow_referral - set up mountpoint when hitting a referral on moved error
   * @dentry - parent directory
   * @locations - array of NFSv4 server location information
   *
   */
  static struct vfsmount *nfs_follow_referral(struct dentry *dentry,
  					    const struct nfs4_fs_locations *locations)
  {
  	struct vfsmount *mnt = ERR_PTR(-ENOENT);
  	struct nfs_clone_mount mountdata = {
  		.sb = dentry->d_sb,
  		.dentry = dentry,
  		.authflavor = NFS_SB(dentry->d_sb)->client->cl_auth->au_flavor,
  	};
  	char *page = NULL, *page2 = NULL;
  	int loc, error;
  
  	if (locations == NULL || locations->nlocations <= 0)
  		goto out;
  
  	dprintk("%s: referral at %pd2
  ", __func__, dentry);
  
  	page = (char *) __get_free_page(GFP_USER);
  	if (!page)
  		goto out;
  
  	page2 = (char *) __get_free_page(GFP_USER);
  	if (!page2)
  		goto out;
  
  	/* Ensure fs path is a prefix of current dentry path */
  	error = nfs4_validate_fspath(dentry, locations, page, page2);
  	if (error < 0) {
  		mnt = ERR_PTR(error);
  		goto out;
  	}
  
  	for (loc = 0; loc < locations->nlocations; loc++) {
  		const struct nfs4_fs_location *location = &locations->locations[loc];
  
  		if (location == NULL || location->nservers <= 0 ||
  		    location->rootpath.ncomponents == 0)
  			continue;
  
  		mnt = try_location(&mountdata, page, page2, location);
  		if (!IS_ERR(mnt))
  			break;
  	}
  
  out:
  	free_page((unsigned long) page);
  	free_page((unsigned long) page2);
  	dprintk("%s: done
  ", __func__);
  	return mnt;
  }
  
  /*
   * nfs_do_refmount - handle crossing a referral on server
   * @dentry - dentry of referral
   *
   */
  static struct vfsmount *nfs_do_refmount(struct rpc_clnt *client, struct dentry *dentry)
  {
  	struct vfsmount *mnt = ERR_PTR(-ENOMEM);
  	struct dentry *parent;
  	struct nfs4_fs_locations *fs_locations = NULL;
  	struct page *page;
  	int err;
  
  	/* BUG_ON(IS_ROOT(dentry)); */
  	dprintk("%s: enter
  ", __func__);
  
  	page = alloc_page(GFP_KERNEL);
  	if (page == NULL)
  		goto out;
  
  	fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
  	if (fs_locations == NULL)
  		goto out_free;
  
  	/* Get locations */
  	mnt = ERR_PTR(-ENOENT);
  
  	parent = dget_parent(dentry);
  	dprintk("%s: getting locations for %pd2
  ",
  		__func__, dentry);
  
  	err = nfs4_proc_fs_locations(client, parent->d_inode, &dentry->d_name, fs_locations, page);
  	dput(parent);
  	if (err != 0 ||
  	    fs_locations->nlocations <= 0 ||
  	    fs_locations->fs_path.ncomponents <= 0)
  		goto out_free;
  
  	mnt = nfs_follow_referral(dentry, fs_locations);
  out_free:
  	__free_page(page);
  	kfree(fs_locations);
  out:
  	dprintk("%s: done
  ", __func__);
  	return mnt;
  }
  
  struct vfsmount *nfs4_submount(struct nfs_server *server, struct dentry *dentry,
  			       struct nfs_fh *fh, struct nfs_fattr *fattr)
  {
  	rpc_authflavor_t flavor = server->client->cl_auth->au_flavor;
  	struct dentry *parent = dget_parent(dentry);
  	struct inode *dir = parent->d_inode;
  	struct qstr *name = &dentry->d_name;
  	struct rpc_clnt *client;
  	struct vfsmount *mnt;
  
  	/* Look it up again to get its attributes and sec flavor */
  	client = nfs4_proc_lookup_mountpoint(dir, name, fh, fattr);
  	dput(parent);
  	if (IS_ERR(client))
  		return ERR_CAST(client);
  
  	if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) {
  		mnt = nfs_do_refmount(client, dentry);
  		goto out;
  	}
  
  	if (client->cl_auth->au_flavor != flavor)
  		flavor = client->cl_auth->au_flavor;
  	else {
  		rpc_authflavor_t new = nfs4_negotiate_security(dir, name);
  		if ((int)new >= 0)
  			flavor = new;
  	}
  	mnt = nfs_do_submount(dentry, fh, fattr, flavor);
  out:
  	rpc_shutdown_client(client);
  	return mnt;
  }
  
  /*
   * Try one location from the fs_locations array.
   *
   * Returns zero on success, or a negative errno value.
   */
  static int nfs4_try_replacing_one_location(struct nfs_server *server,
  		char *page, char *page2,
  		const struct nfs4_fs_location *location)
  {
  	const size_t addr_bufsize = sizeof(struct sockaddr_storage);
  	struct net *net = rpc_net_ns(server->client);
  	struct sockaddr *sap;
  	unsigned int s;
  	size_t salen;
  	int error;
  
  	sap = kmalloc(addr_bufsize, GFP_KERNEL);
  	if (sap == NULL)
  		return -ENOMEM;
  
  	error = -ENOENT;
  	for (s = 0; s < location->nservers; s++) {
  		const struct nfs4_string *buf = &location->servers[s];
  		char *hostname;
  
  		if (buf->len <= 0 || buf->len > PAGE_SIZE)
  			continue;
  
  		if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len) != NULL)
  			continue;
  
  		salen = nfs_parse_server_name(buf->data, buf->len,
  						sap, addr_bufsize, net);
  		if (salen == 0)
  			continue;
  		rpc_set_port(sap, NFS_PORT);
  
  		error = -ENOMEM;
  		hostname = kstrndup(buf->data, buf->len, GFP_KERNEL);
  		if (hostname == NULL)
  			break;
  
  		error = nfs4_update_server(server, hostname, sap, salen, net);
  		kfree(hostname);
  		if (error == 0)
  			break;
  	}
  
  	kfree(sap);
  	return error;
  }
  
  /**
   * nfs4_replace_transport - set up transport to destination server
   *
   * @server: export being migrated
   * @locations: fs_locations array
   *
   * Returns zero on success, or a negative errno value.
   *
   * The client tries all the entries in the "locations" array, in the
   * order returned by the server, until one works or the end of the
   * array is reached.
   */
  int nfs4_replace_transport(struct nfs_server *server,
  			   const struct nfs4_fs_locations *locations)
  {
  	char *page = NULL, *page2 = NULL;
  	int loc, error;
  
  	error = -ENOENT;
  	if (locations == NULL || locations->nlocations <= 0)
  		goto out;
  
  	error = -ENOMEM;
  	page = (char *) __get_free_page(GFP_USER);
  	if (!page)
  		goto out;
  	page2 = (char *) __get_free_page(GFP_USER);
  	if (!page2)
  		goto out;
  
  	for (loc = 0; loc < locations->nlocations; loc++) {
  		const struct nfs4_fs_location *location =
  						&locations->locations[loc];
  
  		if (location == NULL || location->nservers <= 0 ||
  		    location->rootpath.ncomponents == 0)
  			continue;
  
  		error = nfs4_try_replacing_one_location(server, page,
  							page2, location);
  		if (error == 0)
  			break;
  	}
  
  out:
  	free_page((unsigned long)page);
  	free_page((unsigned long)page2);
  	return error;
  }