// SPDX-License-Identifier: GPL-2.0

  /*
   * 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/module.h>

  #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 "nfs.h"

  #include "dns_resolve.h"

  
  #define NFSDBG_FACILITY		NFSDBG_VFS
  
  /*

   * Work out the length that an NFSv4 path would render to as a standard posix
   * path, with a leading slash but no terminating slash.
   */
  static ssize_t nfs4_pathname_len(const struct nfs4_pathname *pathname)
  {
  	ssize_t len = 0;
  	int i;
  
  	for (i = 0; i < pathname->ncomponents; i++) {
  		const struct nfs4_string *component = &pathname->components[i];
  
  		if (component->len > NAME_MAX)
  			goto too_long;
  		len += 1 + component->len; /* Adding "/foo" */
  		if (len > PATH_MAX)
  			goto too_long;
  	}
  	return len;
  
  too_long:
  	return -ENAMETOOLONG;
  }
  
  /*

   * Convert the NFSv4 pathname components into a standard posix path.

   */

  static char *nfs4_pathname_string(const struct nfs4_pathname *pathname,
  				  unsigned short *_len)

  {

  	ssize_t len;
  	char *buf, *p;
  	int i;
  
  	len = nfs4_pathname_len(pathname);
  	if (len < 0)
  		return ERR_PTR(len);
  	*_len = len;
  
  	p = buf = kmalloc(len + 1, GFP_KERNEL);
  	if (!buf)
  		return ERR_PTR(-ENOMEM);

  	for (i = 0; i < pathname->ncomponents; i++) {
  		const struct nfs4_string *component = &pathname->components[i];
  
  		*p++ = '/';
  		memcpy(p, component->data, component->len);
  		p += component->len;

  	}

  
  	*p = 0;
  	return buf;

  }

  /*

   * 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,

  				struct nfs_fs_context *ctx)

  {

  	const char *path;
  	char *fs_path;

  	unsigned short len;

  	char *buf;

  	int n;

  	buf = kmalloc(4096, GFP_KERNEL);

  	if (!buf)
  		return -ENOMEM;

  	path = nfs4_path(dentry, buf, 4096);
  	if (IS_ERR(path)) {
  		kfree(buf);

  		return PTR_ERR(path);

  	}

  	fs_path = nfs4_pathname_string(&locations->fs_path, &len);
  	if (IS_ERR(fs_path)) {
  		kfree(buf);

  		return PTR_ERR(fs_path);

  	}

  	n = strncmp(path, fs_path, len);
  	kfree(buf);
  	kfree(fs_path);
  	if (n != 0) {

  		dprintk("%s: path %s does not begin with fsroot %s
  ",

  			__func__, path, ctx->nfs_server.export_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

   * @clnt: pointer to rpc_clnt

   * @server: NFS server struct

   * @flavors: List of security tuples returned by SECINFO procedure
   *

   * Return an rpc client that uses the first security mechanism in
   * "flavors" that is locally supported.  The "flavors" array

   * is searched in the order returned from the server, per RFC 3530

   * recommendation and each flavor is checked for membership in the
   * sec= mount option list if it exists.

   *
   * Return -EPERM if no matching flavor is found in the array.

   *
   * Please call rpc_shutdown_client() when you are done with this rpc client.
   *

   */

  static struct rpc_clnt *nfs_find_best_sec(struct rpc_clnt *clnt,
  					  struct nfs_server *server,

  					  struct nfs4_secinfo_flavors *flavors)

  {

  	rpc_authflavor_t pflavor;

  	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:

  			pflavor = rpcauth_get_pseudoflavor(secinfo->flavor,

  							&secinfo->flavor_info);

  			/* does the pseudoflavor match a sec= mount opt? */
  			if (pflavor != RPC_AUTH_MAXFLAVOR &&
  			    nfs_auth_info_match(&server->auth_info, pflavor)) {
  				struct rpc_clnt *new;
  				struct rpc_cred *cred;
  
  				/* Cloning creates an rpc_auth for the flavor */
  				new = rpc_clone_client_set_auth(clnt, pflavor);
  				if (IS_ERR(new))
  					continue;
  				/**
  				* Check that the user actually can use the
  				* flavor. This is mostly for RPC_AUTH_GSS
  				* where cr_init obtains a gss context
  				*/
  				cred = rpcauth_lookupcred(new->cl_auth, 0);
  				if (IS_ERR(cred)) {
  					rpc_shutdown_client(new);
  					continue;
  				}
  				put_rpccred(cred);
  				return new;
  			}

  		}
  	}

  	return ERR_PTR(-EPERM);

  }

  /**
   * nfs4_negotiate_security - in response to an NFS4ERR_WRONGSEC on lookup,
   * return an rpc_clnt that uses the best available security flavor with
   * respect to the secinfo flavor list and the sec= mount options.
   *
   * @clnt: RPC client to clone
   * @inode: directory inode
   * @name: lookup name
   *
   * Please call rpc_shutdown_client() when you are done with this rpc client.
   */
  struct rpc_clnt *
  nfs4_negotiate_security(struct rpc_clnt *clnt, struct inode *inode,

  					const struct qstr *name)

  {
  	struct page *page;
  	struct nfs4_secinfo_flavors *flavors;

  	struct rpc_clnt *new;

  	int err;
  
  	page = alloc_page(GFP_KERNEL);
  	if (!page)

  		return ERR_PTR(-ENOMEM);

  	flavors = page_address(page);
  
  	err = nfs4_proc_secinfo(inode, name, flavors);
  	if (err < 0) {

  		new = ERR_PTR(err);

  		goto out;
  	}

  	new = nfs_find_best_sec(clnt, NFS_SERVER(inode), flavors);

  
  out:
  	put_page(page);

  	return new;

  }

  static int try_location(struct fs_context *fc,
  			const struct nfs4_fs_location *location)

  {

  	struct nfs_fs_context *ctx = nfs_fc2context(fc);
  	unsigned int len, s;
  	char *export_path, *source, *p;
  	int ret = -ENOENT;
  
  	/* Allocate a buffer big enough to hold any of the hostnames plus a
  	 * terminating char and also a buffer big enough to hold the hostname
  	 * plus a colon plus the path.
  	 */
  	len = 0;

  	for (s = 0; s < location->nservers; s++) {

  		const struct nfs4_string *buf = &location->servers[s];

  		if (buf->len > len)
  			len = buf->len;
  	}

  	kfree(ctx->nfs_server.hostname);
  	ctx->nfs_server.hostname = kmalloc(len + 1, GFP_KERNEL);
  	if (!ctx->nfs_server.hostname)
  		return -ENOMEM;
  
  	export_path = nfs4_pathname_string(&location->rootpath,
  					   &ctx->nfs_server.export_path_len);
  	if (IS_ERR(export_path))
  		return PTR_ERR(export_path);

  	kfree(ctx->nfs_server.export_path);

  	ctx->nfs_server.export_path = export_path;
  
  	source = kmalloc(len + 1 + ctx->nfs_server.export_path_len + 1,
  			 GFP_KERNEL);
  	if (!source)
  		return -ENOMEM;
  
  	kfree(fc->source);
  	fc->source = source;

  	for (s = 0; s < location->nservers; s++) {
  		const struct nfs4_string *buf = &location->servers[s];

  		if (memchr(buf->data, IPV6_SCOPE_DELIMITER, buf->len))
  			continue;

  		ctx->nfs_server.addrlen =

  			nfs_parse_server_name(buf->data, buf->len,

  					      &ctx->nfs_server.address,
  					      sizeof(ctx->nfs_server._address),

  					      fc->net_ns);

  		if (ctx->nfs_server.addrlen == 0)

  			continue;

  		rpc_set_port(&ctx->nfs_server.address, NFS_PORT);

  
  		memcpy(ctx->nfs_server.hostname, buf->data, buf->len);
  		ctx->nfs_server.hostname[buf->len] = '\0';

  		p = source;
  		memcpy(p, buf->data, buf->len);
  		p += buf->len;
  		*p++ = ':';
  		memcpy(p, ctx->nfs_server.export_path, ctx->nfs_server.export_path_len);
  		p += ctx->nfs_server.export_path_len;
  		*p = 0;

  		ret = nfs4_get_referral_tree(fc);
  		if (ret == 0)
  			return 0;

  	}

  
  	return ret;

  }

  /**
   * nfs_follow_referral - set up mountpoint when hitting a referral on moved error

   * @fc: pointer to struct nfs_fs_context

   * @locations: array of NFSv4 server location information

   *
   */

  static int nfs_follow_referral(struct fs_context *fc,
  			       const struct nfs4_fs_locations *locations)

  {

  	struct nfs_fs_context *ctx = nfs_fc2context(fc);

  	int loc, error;

  
  	if (locations == NULL || locations->nlocations <= 0)

  		return -ENOENT;

  	dprintk("%s: referral at %pd2
  ", __func__, ctx->clone_data.dentry);

  	/* Ensure fs path is a prefix of current dentry path */

  	error = nfs4_validate_fspath(ctx->clone_data.dentry, locations, ctx);
  	if (error < 0)
  		return error;

  	error = -ENOENT;

  	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 = try_location(fc, location);
  		if (error == 0)
  			return 0;

  	}

  	return error;

  }
  
  /*
   * nfs_do_refmount - handle crossing a referral on server
   * @dentry - dentry of referral

   *
   */

  static int nfs_do_refmount(struct fs_context *fc, struct rpc_clnt *client)

  {

  	struct nfs_fs_context *ctx = nfs_fc2context(fc);
  	struct dentry *dentry, *parent;

  	struct nfs4_fs_locations *fs_locations = NULL;
  	struct page *page;

  	int err = -ENOMEM;

  
  	/* BUG_ON(IS_ROOT(dentry)); */

  	page = alloc_page(GFP_KERNEL);

  	if (!page)
  		return -ENOMEM;

  
  	fs_locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);

  	if (!fs_locations)

  		goto out_free;
  
  	/* Get locations */

  	dentry = ctx->clone_data.dentry;

  	parent = dget_parent(dentry);

  	dprintk("%s: getting locations for %pd2
  ",
  		__func__, dentry);

  	err = nfs4_proc_fs_locations(client, d_inode(parent), &dentry->d_name, fs_locations, page);

  	dput(parent);

  	if (err != 0)
  		goto out_free_2;
  
  	err = -ENOENT;
  	if (fs_locations->nlocations <= 0 ||

  	    fs_locations->fs_path.ncomponents <= 0)

  		goto out_free_2;

  	err = nfs_follow_referral(fc, fs_locations);
  out_free_2:
  	kfree(fs_locations);

  out_free:
  	__free_page(page);

  	return err;

  }

  int nfs4_submount(struct fs_context *fc, struct nfs_server *server)

  {

  	struct nfs_fs_context *ctx = nfs_fc2context(fc);
  	struct dentry *dentry = ctx->clone_data.dentry;

  	struct dentry *parent = dget_parent(dentry);

  	struct inode *dir = d_inode(parent);

  	struct rpc_clnt *client;

  	int ret;

  
  	/* Look it up again to get its attributes and sec flavor */

  	client = nfs4_proc_lookup_mountpoint(dir, dentry, ctx->mntfh,

  					     ctx->clone_data.fattr);

  	dput(parent);
  	if (IS_ERR(client))

  		return PTR_ERR(client);

  	ctx->selected_flavor = client->cl_auth->au_flavor;
  	if (ctx->clone_data.fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) {
  		ret = nfs_do_refmount(fc, client);
  	} else {
  		ret = nfs_do_submount(fc);

  	}

  
  	rpc_shutdown_client(client);

  	return ret;

  }

  
  /*
   * 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 = kmemdup_nul(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;
  }