text: // SPDX-License-Identifier: GPL-2.0-only
  /*
   *  linux/fs/9p/v9fs.c
   *
   *  This file contains functions assisting in mapping VFS to 9P2000
   *
   *  Copyright (C) 2004-2008 by Eric Van Hensbergen <ericvh@gmail.com>
   *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
   */
  
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  
  #include <linux/module.h>
  #include <linux/errno.h>
  #include <linux/fs.h>
  #include <linux/sched.h>
  #include <linux/cred.h>
  #include <linux/parser.h>
  #include <linux/idr.h>
  #include <linux/slab.h>
  #include <linux/seq_file.h>
  #include <net/9p/9p.h>
  #include <net/9p/client.h>
  #include <net/9p/transport.h>
  #include "v9fs.h"
  #include "v9fs_vfs.h"
  #include "cache.h"
  
  static DEFINE_SPINLOCK(v9fs_sessionlist_lock);
  static LIST_HEAD(v9fs_sessionlist);
  struct kmem_cache *v9fs_inode_cache;
  
  /*
   * Option Parsing (code inspired by NFS code)
   *  NOTE: each transport will parse its own options
   */
  
  enum {
  	/* Options that take integer arguments */
  	Opt_debug, Opt_dfltuid, Opt_dfltgid, Opt_afid,
  	/* String options */
  	Opt_uname, Opt_remotename, Opt_cache, Opt_cachetag,
  	/* Options that take no arguments */
  	Opt_nodevmap,
  	/* Cache options */
  	Opt_cache_loose, Opt_fscache, Opt_mmap,
  	/* Access options */
  	Opt_access, Opt_posixacl,
  	/* Lock timeout option */
  	Opt_locktimeout,
  	/* Error token */
  	Opt_err
  };
  
  static const match_table_t tokens = {
  	{Opt_debug, "debug=%x"},
  	{Opt_dfltuid, "dfltuid=%u"},
  	{Opt_dfltgid, "dfltgid=%u"},
  	{Opt_afid, "afid=%u"},
  	{Opt_uname, "uname=%s"},
  	{Opt_remotename, "aname=%s"},
  	{Opt_nodevmap, "nodevmap"},
  	{Opt_cache, "cache=%s"},
  	{Opt_cache_loose, "loose"},
  	{Opt_fscache, "fscache"},
  	{Opt_mmap, "mmap"},
  	{Opt_cachetag, "cachetag=%s"},
  	{Opt_access, "access=%s"},
  	{Opt_posixacl, "posixacl"},
  	{Opt_locktimeout, "locktimeout=%u"},
  	{Opt_err, NULL}
  };
  
  static const char *const v9fs_cache_modes[nr__p9_cache_modes] = {
  	[CACHE_NONE]	= "none",
  	[CACHE_MMAP]	= "mmap",
  	[CACHE_LOOSE]	= "loose",
  	[CACHE_FSCACHE]	= "fscache",
  };
  
  /* Interpret mount options for cache mode */
  static int get_cache_mode(char *s)
  {
  	int version = -EINVAL;
  
  	if (!strcmp(s, "loose")) {
  		version = CACHE_LOOSE;
  		p9_debug(P9_DEBUG_9P, "Cache mode: loose\n");
  	} else if (!strcmp(s, "fscache")) {
  		version = CACHE_FSCACHE;
  		p9_debug(P9_DEBUG_9P, "Cache mode: fscache\n");
  	} else if (!strcmp(s, "mmap")) {
  		version = CACHE_MMAP;
  		p9_debug(P9_DEBUG_9P, "Cache mode: mmap\n");
  	} else if (!strcmp(s, "none")) {
  		version = CACHE_NONE;
  		p9_debug(P9_DEBUG_9P, "Cache mode: none\n");
  	} else
  		pr_info("Unknown Cache mode %s\n", s);
  	return version;
  }
  
  /*
   * Display the mount options in /proc/mounts.
   */
  int v9fs_show_options(struct seq_file *m, struct dentry *root)
  {
  	struct v9fs_session_info *v9ses = root->d_sb->s_fs_info;
  
  	if (v9ses->debug)
  		seq_printf(m, ",debug=%x", v9ses->debug);
  	if (!uid_eq(v9ses->dfltuid, V9FS_DEFUID))
  		seq_printf(m, ",dfltuid=%u",
  			   from_kuid_munged(&init_user_ns, v9ses->dfltuid));
  	if (!gid_eq(v9ses->dfltgid, V9FS_DEFGID))
  		seq_printf(m, ",dfltgid=%u",
  			   from_kgid_munged(&init_user_ns, v9ses->dfltgid));
  	if (v9ses->afid != ~0)
  		seq_printf(m, ",afid=%u", v9ses->afid);
  	if (strcmp(v9ses->uname, V9FS_DEFUSER) != 0)
  		seq_printf(m, ",uname=%s", v9ses->uname);
  	if (strcmp(v9ses->aname, V9FS_DEFANAME) != 0)
  		seq_printf(m, ",aname=%s", v9ses->aname);
  	if (v9ses->nodev)
  		seq_puts(m, ",nodevmap");
  	if (v9ses->cache)
  		seq_printf(m, ",%s", v9fs_cache_modes[v9ses->cache]);
  #ifdef CONFIG_9P_FSCACHE
  	if (v9ses->cachetag && v9ses->cache == CACHE_FSCACHE)
  		seq_printf(m, ",cachetag=%s", v9ses->cachetag);
  #endif
  
  	switch (v9ses->flags & V9FS_ACCESS_MASK) {
  	case V9FS_ACCESS_USER:
  		seq_puts(m, ",access=user");
  		break;
  	case V9FS_ACCESS_ANY:
  		seq_puts(m, ",access=any");
  		break;
  	case V9FS_ACCESS_CLIENT:
  		seq_puts(m, ",access=client");
  		break;
  	case V9FS_ACCESS_SINGLE:
  		seq_printf(m, ",access=%u",
  			   from_kuid_munged(&init_user_ns, v9ses->uid));
  		break;
  	}
  
  	if (v9ses->flags & V9FS_POSIX_ACL)
  		seq_puts(m, ",posixacl");
  
  	return p9_show_client_options(m, v9ses->clnt);
  }
  
  /**
   * v9fs_parse_options - parse mount options into session structure
   * @v9ses: existing v9fs session information
   *
   * Return 0 upon success, -ERRNO upon failure.
   */
  
  static int v9fs_parse_options(struct v9fs_session_info *v9ses, char *opts)
  {
  	char *options, *tmp_options;
  	substring_t args[MAX_OPT_ARGS];
  	char *p;
  	int option = 0;
  	char *s, *e;
  	int ret = 0;
  
  	/* setup defaults */
  	v9ses->afid = ~0;
  	v9ses->debug = 0;
  	v9ses->cache = CACHE_NONE;
  #ifdef CONFIG_9P_FSCACHE
  	v9ses->cachetag = NULL;
  #endif
  	v9ses->session_lock_timeout = P9_LOCK_TIMEOUT;
  
  	if (!opts)
  		return 0;
  
  	tmp_options = kstrdup(opts, GFP_KERNEL);
  	if (!tmp_options) {
  		ret = -ENOMEM;
  		goto fail_option_alloc;
  	}
  	options = tmp_options;
  
  	while ((p = strsep(&options, ",")) != NULL) {
  		int token, r;
  		if (!*p)
  			continue;
  		token = match_token(p, tokens, args);
  		switch (token) {
  		case Opt_debug:
  			r = match_int(&args[0], &option);
  			if (r < 0) {
  				p9_debug(P9_DEBUG_ERROR,
  					 "integer field, but no integer?\n");
  				ret = r;
  			} else {
  				v9ses->debug = option;
  #ifdef CONFIG_NET_9P_DEBUG
  				p9_debug_level = option;
  #endif
  			}
  			break;
  
  		case Opt_dfltuid:
  			r = match_int(&args[0], &option);
  			if (r < 0) {
  				p9_debug(P9_DEBUG_ERROR,
  					 "integer field, but no integer?\n");
  				ret = r;
  				continue;
  			}
  			v9ses->dfltuid = make_kuid(current_user_ns(), option);
  			if (!uid_valid(v9ses->dfltuid)) {
  				p9_debug(P9_DEBUG_ERROR,
  					 "uid field, but not a uid?\n");
  				ret = -EINVAL;
  			}
  			break;
  		case Opt_dfltgid:
  			r = match_int(&args[0], &option);
  			if (r < 0) {
  				p9_debug(P9_DEBUG_ERROR,
  					 "integer field, but no integer?\n");
  				ret = r;
  				continue;
  			}
  			v9ses->dfltgid = make_kgid(current_user_ns(), option);
  			if (!gid_valid(v9ses->dfltgid)) {
  				p9_debug(P9_DEBUG_ERROR,
  					 "gid field, but not a gid?\n");
  				ret = -EINVAL;
  			}
  			break;
  		case Opt_afid:
  			r = match_int(&args[0], &option);
  			if (r < 0) {
  				p9_debug(P9_DEBUG_ERROR,
  					 "integer field, but no integer?\n");
  				ret = r;
  			} else {
  				v9ses->afid = option;
  			}
  			break;
  		case Opt_uname:
  			kfree(v9ses->uname);
  			v9ses->uname = match_strdup(&args[0]);
  			if (!v9ses->uname) {
  				ret = -ENOMEM;
  				goto free_and_return;
  			}
  			break;
  		case Opt_remotename:
  			kfree(v9ses->aname);
  			v9ses->aname = match_strdup(&args[0]);
  			if (!v9ses->aname) {
  				ret = -ENOMEM;
  				goto free_and_return;
  			}
  			break;
  		case Opt_nodevmap:
  			v9ses->nodev = 1;
  			break;
  		case Opt_cache_loose:
  			v9ses->cache = CACHE_LOOSE;
  			break;
  		case Opt_fscache:
  			v9ses->cache = CACHE_FSCACHE;
  			break;
  		case Opt_mmap:
  			v9ses->cache = CACHE_MMAP;
  			break;
  		case Opt_cachetag:
  #ifdef CONFIG_9P_FSCACHE
  			kfree(v9ses->cachetag);
  			v9ses->cachetag = match_strdup(&args[0]);
  			if (!v9ses->cachetag) {
  				ret = -ENOMEM;
  				goto free_and_return;
  			}
  #endif
  			break;
  		case Opt_cache:
  			s = match_strdup(&args[0]);
  			if (!s) {
  				ret = -ENOMEM;
  				p9_debug(P9_DEBUG_ERROR,
  					 "problem allocating copy of cache arg\n");
  				goto free_and_return;
  			}
  			r = get_cache_mode(s);
  			if (r < 0)
  				ret = r;
  			else
  				v9ses->cache = r;
  
  			kfree(s);
  			break;
  
  		case Opt_access:
  			s = match_strdup(&args[0]);
  			if (!s) {
  				ret = -ENOMEM;
  				p9_debug(P9_DEBUG_ERROR,
  					 "problem allocating copy of access arg\n");
  				goto free_and_return;
  			}
  
  			v9ses->flags &= ~V9FS_ACCESS_MASK;
  			if (strcmp(s, "user") == 0)
  				v9ses->flags |= V9FS_ACCESS_USER;
  			else if (strcmp(s, "any") == 0)
  				v9ses->flags |= V9FS_ACCESS_ANY;
  			else if (strcmp(s, "client") == 0) {
  				v9ses->flags |= V9FS_ACCESS_CLIENT;
  			} else {
  				uid_t uid;
  				v9ses->flags |= V9FS_ACCESS_SINGLE;
  				uid = simple_strtoul(s, &e, 10);
  				if (*e != '\0') {
  					ret = -EINVAL;
  					pr_info("Unknown access argument %s\n",
  						s);
  					kfree(s);
  					continue;
  				}
  				v9ses->uid = make_kuid(current_user_ns(), uid);
  				if (!uid_valid(v9ses->uid)) {
  					ret = -EINVAL;
  					pr_info("Unknown uid %s\n", s);
  				}
  			}
  
  			kfree(s);
  			break;
  
  		case Opt_posixacl:
  #ifdef CONFIG_9P_FS_POSIX_ACL
  			v9ses->flags |= V9FS_POSIX_ACL;
  #else
  			p9_debug(P9_DEBUG_ERROR,
  				 "Not defined CONFIG_9P_FS_POSIX_ACL. Ignoring posixacl option\n");
  #endif
  			break;
  
  		case Opt_locktimeout:
  			r = match_int(&args[0], &option);
  			if (r < 0) {
  				p9_debug(P9_DEBUG_ERROR,
  					 "integer field, but no integer?\n");
  				ret = r;
  				continue;
  			}
  			if (option < 1) {
  				p9_debug(P9_DEBUG_ERROR,
  					 "locktimeout must be a greater than zero integer.\n");
  				ret = -EINVAL;
  				continue;
  			}
  			v9ses->session_lock_timeout = (long)option * HZ;
  			break;
  
  		default:
  			continue;
  		}
  	}
  
  free_and_return:
  	kfree(tmp_options);
  fail_option_alloc:
  	return ret;
  }
  
  /**
   * v9fs_session_init - initialize session
   * @v9ses: session information structure
   * @dev_name: device being mounted
   * @data: options
   *
   */
  
  struct p9_fid *v9fs_session_init(struct v9fs_session_info *v9ses,
  		  const char *dev_name, char *data)
  {
  	struct p9_fid *fid;
  	int rc = -ENOMEM;
  
  	v9ses->uname = kstrdup(V9FS_DEFUSER, GFP_KERNEL);
  	if (!v9ses->uname)
  		goto err_names;
  
  	v9ses->aname = kstrdup(V9FS_DEFANAME, GFP_KERNEL);
  	if (!v9ses->aname)
  		goto err_names;
  	init_rwsem(&v9ses->rename_sem);
  
  	v9ses->uid = INVALID_UID;
  	v9ses->dfltuid = V9FS_DEFUID;
  	v9ses->dfltgid = V9FS_DEFGID;
  
  	v9ses->clnt = p9_client_create(dev_name, data);
  	if (IS_ERR(v9ses->clnt)) {
  		rc = PTR_ERR(v9ses->clnt);
  		p9_debug(P9_DEBUG_ERROR, "problem initializing 9p client\n");
  		goto err_names;
  	}
  
  	v9ses->flags = V9FS_ACCESS_USER;
  
  	if (p9_is_proto_dotl(v9ses->clnt)) {
  		v9ses->flags = V9FS_ACCESS_CLIENT;
  		v9ses->flags |= V9FS_PROTO_2000L;
  	} else if (p9_is_proto_dotu(v9ses->clnt)) {
  		v9ses->flags |= V9FS_PROTO_2000U;
  	}
  
  	rc = v9fs_parse_options(v9ses, data);
  	if (rc < 0)
  		goto err_clnt;
  
  	v9ses->maxdata = v9ses->clnt->msize - P9_IOHDRSZ;
  
  	if (!v9fs_proto_dotl(v9ses) &&
  	    ((v9ses->flags & V9FS_ACCESS_MASK) == V9FS_ACCESS_CLIENT)) {
  		/*
  		 * We support ACCESS_CLIENT only for dotl.
  		 * Fall back to ACCESS_USER
  		 */
  		v9ses->flags &= ~V9FS_ACCESS_MASK;
  		v9ses->flags |= V9FS_ACCESS_USER;
  	}
  	/*FIXME !! */
  	/* for legacy mode, fall back to V9FS_ACCESS_ANY */
  	if (!(v9fs_proto_dotu(v9ses) || v9fs_proto_dotl(v9ses)) &&
  		((v9ses->flags&V9FS_ACCESS_MASK) == V9FS_ACCESS_USER)) {
  
  		v9ses->flags &= ~V9FS_ACCESS_MASK;
  		v9ses->flags |= V9FS_ACCESS_ANY;
  		v9ses->uid = INVALID_UID;
  	}
  	if (!v9fs_proto_dotl(v9ses) ||
  		!((v9ses->flags & V9FS_ACCESS_MASK) == V9FS_ACCESS_CLIENT)) {
  		/*
  		 * We support ACL checks on clinet only if the protocol is
  		 * 9P2000.L and access is V9FS_ACCESS_CLIENT.
  		 */
  		v9ses->flags &= ~V9FS_ACL_MASK;
  	}
  
  	fid = p9_client_attach(v9ses->clnt, NULL, v9ses->uname, INVALID_UID,
  							v9ses->aname);
  	if (IS_ERR(fid)) {
  		rc = PTR_ERR(fid);
  		p9_debug(P9_DEBUG_ERROR, "cannot attach\n");
  		goto err_clnt;
  	}
  
  	if ((v9ses->flags & V9FS_ACCESS_MASK) == V9FS_ACCESS_SINGLE)
  		fid->uid = v9ses->uid;
  	else
  		fid->uid = INVALID_UID;
  
  #ifdef CONFIG_9P_FSCACHE
  	/* register the session for caching */
  	v9fs_cache_session_get_cookie(v9ses);
  #endif
  	spin_lock(&v9fs_sessionlist_lock);
  	list_add(&v9ses->slist, &v9fs_sessionlist);
  	spin_unlock(&v9fs_sessionlist_lock);
  
  	return fid;
  
  err_clnt:
  #ifdef CONFIG_9P_FSCACHE
  	kfree(v9ses->cachetag);
  #endif
  	p9_client_destroy(v9ses->clnt);
  err_names:
  	kfree(v9ses->uname);
  	kfree(v9ses->aname);
  	return ERR_PTR(rc);
  }
  
  /**
   * v9fs_session_close - shutdown a session
   * @v9ses: session information structure
   *
   */
  
  void v9fs_session_close(struct v9fs_session_info *v9ses)
  {
  	if (v9ses->clnt) {
  		p9_client_destroy(v9ses->clnt);
  		v9ses->clnt = NULL;
  	}
  
  #ifdef CONFIG_9P_FSCACHE
  	if (v9ses->fscache)
  		v9fs_cache_session_put_cookie(v9ses);
  	kfree(v9ses->cachetag);
  #endif
  	kfree(v9ses->uname);
  	kfree(v9ses->aname);
  
  	spin_lock(&v9fs_sessionlist_lock);
  	list_del(&v9ses->slist);
  	spin_unlock(&v9fs_sessionlist_lock);
  }
  
  /**
   * v9fs_session_cancel - terminate a session
   * @v9ses: session to terminate
   *
   * mark transport as disconnected and cancel all pending requests.
   */
  
  void v9fs_session_cancel(struct v9fs_session_info *v9ses) {
  	p9_debug(P9_DEBUG_ERROR, "cancel session %p\n", v9ses);
  	p9_client_disconnect(v9ses->clnt);
  }
  
  /**
   * v9fs_session_begin_cancel - Begin terminate of a session
   * @v9ses: session to terminate
   *
   * After this call we don't allow any request other than clunk.
   */
  
  void v9fs_session_begin_cancel(struct v9fs_session_info *v9ses)
  {
  	p9_debug(P9_DEBUG_ERROR, "begin cancel session %p\n", v9ses);
  	p9_client_begin_disconnect(v9ses->clnt);
  }
  
  extern int v9fs_error_init(void);
  
  static struct kobject *v9fs_kobj;
  
  #ifdef CONFIG_9P_FSCACHE
  /**
   * caches_show - list caches associated with a session
   *
   * Returns the size of buffer written.
   */
  
  static ssize_t caches_show(struct kobject *kobj,
  			   struct kobj_attribute *attr,
  			   char *buf)
  {
  	ssize_t n = 0, count = 0, limit = PAGE_SIZE;
  	struct v9fs_session_info *v9ses;
  
  	spin_lock(&v9fs_sessionlist_lock);
  	list_for_each_entry(v9ses, &v9fs_sessionlist, slist) {
  		if (v9ses->cachetag) {
  			n = snprintf(buf, limit, "%s\n", v9ses->cachetag);
  			if (n < 0) {
  				count = n;
  				break;
  			}
  
  			count += n;
  			limit -= n;
  		}
  	}
  
  	spin_unlock(&v9fs_sessionlist_lock);
  	return count;
  }
  
  static struct kobj_attribute v9fs_attr_cache = __ATTR_RO(caches);
  #endif /* CONFIG_9P_FSCACHE */
  
  static struct attribute *v9fs_attrs[] = {
  #ifdef CONFIG_9P_FSCACHE
  	&v9fs_attr_cache.attr,
  #endif
  	NULL,
  };
  
  static const struct attribute_group v9fs_attr_group = {
  	.attrs = v9fs_attrs,
  };
  
  /**
   * v9fs_sysfs_init - Initialize the v9fs sysfs interface
   *
   */
  
  static int __init v9fs_sysfs_init(void)
  {
  	v9fs_kobj = kobject_create_and_add("9p", fs_kobj);
  	if (!v9fs_kobj)
  		return -ENOMEM;
  
  	if (sysfs_create_group(v9fs_kobj, &v9fs_attr_group)) {
  		kobject_put(v9fs_kobj);
  		return -ENOMEM;
  	}
  
  	return 0;
  }
  
  /**
   * v9fs_sysfs_cleanup - Unregister the v9fs sysfs interface
   *
   */
  
  static void v9fs_sysfs_cleanup(void)
  {
  	sysfs_remove_group(v9fs_kobj, &v9fs_attr_group);
  	kobject_put(v9fs_kobj);
  }
  
  static void v9fs_inode_init_once(void *foo)
  {
  	struct v9fs_inode *v9inode = (struct v9fs_inode *)foo;
  #ifdef CONFIG_9P_FSCACHE
  	v9inode->fscache = NULL;
  #endif
  	memset(&v9inode->qid, 0, sizeof(v9inode->qid));
  	inode_init_once(&v9inode->vfs_inode);
  }
  
  /**
   * v9fs_init_inode_cache - initialize a cache for 9P
   * Returns 0 on success.
   */
  static int v9fs_init_inode_cache(void)
  {
  	v9fs_inode_cache = kmem_cache_create("v9fs_inode_cache",
  					  sizeof(struct v9fs_inode),
  					  0, (SLAB_RECLAIM_ACCOUNT|
  					      SLAB_MEM_SPREAD|SLAB_ACCOUNT),
  					  v9fs_inode_init_once);
  	if (!v9fs_inode_cache)
  		return -ENOMEM;
  
  	return 0;
  }
  
  /**
   * v9fs_destroy_inode_cache - destroy the cache of 9P inode
   *
   */
  static void v9fs_destroy_inode_cache(void)
  {
  	/*
  	 * Make sure all delayed rcu free inodes are flushed before we
  	 * destroy cache.
  	 */
  	rcu_barrier();
  	kmem_cache_destroy(v9fs_inode_cache);
  }
  
  static int v9fs_cache_register(void)
  {
  	int ret;
  	ret = v9fs_init_inode_cache();
  	if (ret < 0)
  		return ret;
  #ifdef CONFIG_9P_FSCACHE
  	ret = fscache_register_netfs(&v9fs_cache_netfs);
  	if (ret < 0)
  		v9fs_destroy_inode_cache();
  #endif
  	return ret;
  }
  
  static void v9fs_cache_unregister(void)
  {
  	v9fs_destroy_inode_cache();
  #ifdef CONFIG_9P_FSCACHE
  	fscache_unregister_netfs(&v9fs_cache_netfs);
  #endif
  }
  
  /**
   * init_v9fs - Initialize module
   *
   */
  
  static int __init init_v9fs(void)
  {
  	int err;
  	pr_info("Installing v9fs 9p2000 file system support\n");
  	/* TODO: Setup list of registered trasnport modules */
  
  	err = v9fs_cache_register();
  	if (err < 0) {
  		pr_err("Failed to register v9fs for caching\n");
  		return err;
  	}
  
  	err = v9fs_sysfs_init();
  	if (err < 0) {
  		pr_err("Failed to register with sysfs\n");
  		goto out_cache;
  	}
  	err = register_filesystem(&v9fs_fs_type);
  	if (err < 0) {
  		pr_err("Failed to register filesystem\n");
  		goto out_sysfs_cleanup;
  	}
  
  	return 0;
  
  out_sysfs_cleanup:
  	v9fs_sysfs_cleanup();
  
  out_cache:
  	v9fs_cache_unregister();
  
  	return err;
  }
  
  /**
   * exit_v9fs - shutdown module
   *
   */
  
  static void __exit exit_v9fs(void)
  {
  	v9fs_sysfs_cleanup();
  	v9fs_cache_unregister();
  	unregister_filesystem(&v9fs_fs_type);
  }
  
  module_init(init_v9fs)
  module_exit(exit_v9fs)
  
  MODULE_AUTHOR("Latchesar Ionkov <lucho@ionkov.net>");
  MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
  MODULE_AUTHOR("Ron Minnich <rminnich@lanl.gov>");
  MODULE_LICENSE("GPL");
  