| /* |
| * fs/sdcardfs/lookup.c |
| * |
| * Copyright (c) 2013 Samsung Electronics Co. Ltd |
| * Authors: Daeho Jeong, Woojoong Lee, Seunghwan Hyun, |
| * Sunghwan Yun, Sungjong Seo |
| * |
| * This program has been developed as a stackable file system based on |
| * the WrapFS which written by |
| * |
| * Copyright (c) 1998-2011 Erez Zadok |
| * Copyright (c) 2009 Shrikar Archak |
| * Copyright (c) 2003-2011 Stony Brook University |
| * Copyright (c) 2003-2011 The Research Foundation of SUNY |
| * |
| * This file is dual licensed. It may be redistributed and/or modified |
| * under the terms of the Apache 2.0 License OR version 2 of the GNU |
| * General Public License. |
| */ |
| |
| #include "sdcardfs.h" |
| #include "linux/delay.h" |
| |
| /* The dentry cache is just so we have properly sized dentries */ |
| static struct kmem_cache *sdcardfs_dentry_cachep; |
| |
| int sdcardfs_init_dentry_cache(void) |
| { |
| sdcardfs_dentry_cachep = |
| kmem_cache_create("sdcardfs_dentry", |
| sizeof(struct sdcardfs_dentry_info), |
| 0, SLAB_RECLAIM_ACCOUNT, NULL); |
| |
| return sdcardfs_dentry_cachep ? 0 : -ENOMEM; |
| } |
| |
| void sdcardfs_destroy_dentry_cache(void) |
| { |
| kmem_cache_destroy(sdcardfs_dentry_cachep); |
| } |
| |
| void free_dentry_private_data(struct dentry *dentry) |
| { |
| kmem_cache_free(sdcardfs_dentry_cachep, dentry->d_fsdata); |
| dentry->d_fsdata = NULL; |
| } |
| |
| /* allocate new dentry private data */ |
| int new_dentry_private_data(struct dentry *dentry) |
| { |
| struct sdcardfs_dentry_info *info = SDCARDFS_D(dentry); |
| |
| /* use zalloc to init dentry_info.lower_path */ |
| info = kmem_cache_zalloc(sdcardfs_dentry_cachep, GFP_ATOMIC); |
| if (!info) |
| return -ENOMEM; |
| |
| spin_lock_init(&info->lock); |
| dentry->d_fsdata = info; |
| |
| return 0; |
| } |
| |
| struct inode_data { |
| struct inode *lower_inode; |
| userid_t id; |
| }; |
| |
| static int sdcardfs_inode_test(struct inode *inode, void *candidate_data/*void *candidate_lower_inode*/) |
| { |
| struct inode *current_lower_inode = sdcardfs_lower_inode(inode); |
| userid_t current_userid = SDCARDFS_I(inode)->data->userid; |
| |
| if (current_lower_inode == ((struct inode_data *)candidate_data)->lower_inode && |
| current_userid == ((struct inode_data *)candidate_data)->id) |
| return 1; /* found a match */ |
| else |
| return 0; /* no match */ |
| } |
| |
| static int sdcardfs_inode_set(struct inode *inode, void *lower_inode) |
| { |
| /* we do actual inode initialization in sdcardfs_iget */ |
| return 0; |
| } |
| |
| struct inode *sdcardfs_iget(struct super_block *sb, struct inode *lower_inode, userid_t id) |
| { |
| struct sdcardfs_inode_info *info; |
| struct inode_data data; |
| struct inode *inode; /* the new inode to return */ |
| |
| if (!igrab(lower_inode)) |
| return ERR_PTR(-ESTALE); |
| |
| data.id = id; |
| data.lower_inode = lower_inode; |
| inode = iget5_locked(sb, /* our superblock */ |
| /* |
| * hashval: we use inode number, but we can |
| * also use "(unsigned long)lower_inode" |
| * instead. |
| */ |
| lower_inode->i_ino, /* hashval */ |
| sdcardfs_inode_test, /* inode comparison function */ |
| sdcardfs_inode_set, /* inode init function */ |
| &data); /* data passed to test+set fxns */ |
| if (!inode) { |
| iput(lower_inode); |
| return ERR_PTR(-ENOMEM); |
| } |
| /* if found a cached inode, then just return it (after iput) */ |
| if (!(inode->i_state & I_NEW)) { |
| iput(lower_inode); |
| return inode; |
| } |
| |
| /* initialize new inode */ |
| info = SDCARDFS_I(inode); |
| |
| inode->i_ino = lower_inode->i_ino; |
| sdcardfs_set_lower_inode(inode, lower_inode); |
| |
| inode->i_version++; |
| |
| /* use different set of inode ops for symlinks & directories */ |
| if (S_ISDIR(lower_inode->i_mode)) |
| inode->i_op = &sdcardfs_dir_iops; |
| else if (S_ISLNK(lower_inode->i_mode)) |
| inode->i_op = &sdcardfs_symlink_iops; |
| else |
| inode->i_op = &sdcardfs_main_iops; |
| |
| /* use different set of file ops for directories */ |
| if (S_ISDIR(lower_inode->i_mode)) |
| inode->i_fop = &sdcardfs_dir_fops; |
| else |
| inode->i_fop = &sdcardfs_main_fops; |
| |
| inode->i_mapping->a_ops = &sdcardfs_aops; |
| |
| inode->i_atime.tv_sec = 0; |
| inode->i_atime.tv_nsec = 0; |
| inode->i_mtime.tv_sec = 0; |
| inode->i_mtime.tv_nsec = 0; |
| inode->i_ctime.tv_sec = 0; |
| inode->i_ctime.tv_nsec = 0; |
| |
| /* properly initialize special inodes */ |
| if (S_ISBLK(lower_inode->i_mode) || S_ISCHR(lower_inode->i_mode) || |
| S_ISFIFO(lower_inode->i_mode) || S_ISSOCK(lower_inode->i_mode)) |
| init_special_inode(inode, lower_inode->i_mode, |
| lower_inode->i_rdev); |
| |
| /* all well, copy inode attributes */ |
| sdcardfs_copy_and_fix_attrs(inode, lower_inode); |
| fsstack_copy_inode_size(inode, lower_inode); |
| |
| unlock_new_inode(inode); |
| return inode; |
| } |
| |
| /* |
| * Helper interpose routine, called directly by ->lookup to handle |
| * spliced dentries. |
| */ |
| static struct dentry *__sdcardfs_interpose(struct dentry *dentry, |
| struct super_block *sb, |
| struct path *lower_path, |
| userid_t id) |
| { |
| struct inode *inode; |
| struct inode *lower_inode; |
| struct super_block *lower_sb; |
| struct dentry *ret_dentry; |
| |
| lower_inode = d_inode(lower_path->dentry); |
| lower_sb = sdcardfs_lower_super(sb); |
| |
| /* check that the lower file system didn't cross a mount point */ |
| if (lower_inode->i_sb != lower_sb) { |
| ret_dentry = ERR_PTR(-EXDEV); |
| goto out; |
| } |
| |
| /* |
| * We allocate our new inode below by calling sdcardfs_iget, |
| * which will initialize some of the new inode's fields |
| */ |
| |
| /* inherit lower inode number for sdcardfs's inode */ |
| inode = sdcardfs_iget(sb, lower_inode, id); |
| if (IS_ERR(inode)) { |
| ret_dentry = ERR_CAST(inode); |
| goto out; |
| } |
| |
| ret_dentry = d_splice_alias(inode, dentry); |
| dentry = ret_dentry ?: dentry; |
| if (!IS_ERR(dentry)) |
| update_derived_permission_lock(dentry); |
| out: |
| return ret_dentry; |
| } |
| |
| /* |
| * Connect an sdcardfs inode dentry/inode with several lower ones. This is |
| * the classic stackable file system "vnode interposition" action. |
| * |
| * @dentry: sdcardfs's dentry which interposes on lower one |
| * @sb: sdcardfs's super_block |
| * @lower_path: the lower path (caller does path_get/put) |
| */ |
| int sdcardfs_interpose(struct dentry *dentry, struct super_block *sb, |
| struct path *lower_path, userid_t id) |
| { |
| struct dentry *ret_dentry; |
| |
| ret_dentry = __sdcardfs_interpose(dentry, sb, lower_path, id); |
| return PTR_ERR(ret_dentry); |
| } |
| |
| struct sdcardfs_name_data { |
| struct dir_context ctx; |
| const struct qstr *to_find; |
| char *name; |
| bool found; |
| }; |
| |
| static int sdcardfs_name_match(struct dir_context *ctx, const char *name, |
| int namelen, loff_t offset, u64 ino, unsigned int d_type) |
| { |
| struct sdcardfs_name_data *buf = container_of(ctx, struct sdcardfs_name_data, ctx); |
| struct qstr candidate = QSTR_INIT(name, namelen); |
| |
| if (qstr_case_eq(buf->to_find, &candidate)) { |
| memcpy(buf->name, name, namelen); |
| buf->name[namelen] = 0; |
| buf->found = true; |
| return 1; |
| } |
| return 0; |
| } |
| |
| /* |
| * Main driver function for sdcardfs's lookup. |
| * |
| * Returns: NULL (ok), ERR_PTR if an error occurred. |
| * Fills in lower_parent_path with <dentry,mnt> on success. |
| */ |
| static struct dentry *__sdcardfs_lookup(struct dentry *dentry, |
| unsigned int flags, struct path *lower_parent_path, userid_t id) |
| { |
| int err = 0; |
| struct vfsmount *lower_dir_mnt; |
| struct dentry *lower_dir_dentry = NULL; |
| struct dentry *lower_dentry; |
| const struct qstr *name; |
| struct path lower_path; |
| struct qstr dname; |
| struct dentry *ret_dentry = NULL; |
| struct sdcardfs_sb_info *sbi; |
| |
| sbi = SDCARDFS_SB(dentry->d_sb); |
| /* must initialize dentry operations */ |
| d_set_d_op(dentry, &sdcardfs_ci_dops); |
| |
| if (IS_ROOT(dentry)) |
| goto out; |
| |
| name = &dentry->d_name; |
| |
| /* now start the actual lookup procedure */ |
| lower_dir_dentry = lower_parent_path->dentry; |
| lower_dir_mnt = lower_parent_path->mnt; |
| |
| /* Use vfs_path_lookup to check if the dentry exists or not */ |
| err = vfs_path_lookup(lower_dir_dentry, lower_dir_mnt, name->name, 0, |
| &lower_path); |
| /* check for other cases */ |
| if (err == -ENOENT) { |
| struct file *file; |
| const struct cred *cred = current_cred(); |
| |
| struct sdcardfs_name_data buffer = { |
| .ctx.actor = sdcardfs_name_match, |
| .to_find = name, |
| .name = __getname(), |
| .found = false, |
| }; |
| |
| if (!buffer.name) { |
| err = -ENOMEM; |
| goto out; |
| } |
| file = dentry_open(lower_parent_path, O_RDONLY, cred); |
| if (IS_ERR(file)) { |
| err = PTR_ERR(file); |
| goto put_name; |
| } |
| err = iterate_dir(file, &buffer.ctx); |
| fput(file); |
| if (err) |
| goto put_name; |
| |
| if (buffer.found) |
| err = vfs_path_lookup(lower_dir_dentry, |
| lower_dir_mnt, |
| buffer.name, 0, |
| &lower_path); |
| else |
| err = -ENOENT; |
| put_name: |
| __putname(buffer.name); |
| } |
| |
| /* no error: handle positive dentries */ |
| if (!err) { |
| /* check if the dentry is an obb dentry |
| * if true, the lower_inode must be replaced with |
| * the inode of the graft path |
| */ |
| |
| if (need_graft_path(dentry)) { |
| |
| /* setup_obb_dentry() |
| * The lower_path will be stored to the dentry's orig_path |
| * and the base obbpath will be copyed to the lower_path variable. |
| * if an error returned, there's no change in the lower_path |
| * returns: -ERRNO if error (0: no error) |
| */ |
| err = setup_obb_dentry(dentry, &lower_path); |
| |
| if (err) { |
| /* if the sbi->obbpath is not available, we can optionally |
| * setup the lower_path with its orig_path. |
| * but, the current implementation just returns an error |
| * because the sdcard daemon also regards this case as |
| * a lookup fail. |
| */ |
| pr_info("sdcardfs: base obbpath is not available\n"); |
| sdcardfs_put_reset_orig_path(dentry); |
| goto out; |
| } |
| } |
| |
| sdcardfs_set_lower_path(dentry, &lower_path); |
| ret_dentry = |
| __sdcardfs_interpose(dentry, dentry->d_sb, &lower_path, id); |
| if (IS_ERR(ret_dentry)) { |
| err = PTR_ERR(ret_dentry); |
| /* path_put underlying path on error */ |
| sdcardfs_put_reset_lower_path(dentry); |
| } |
| goto out; |
| } |
| |
| /* |
| * We don't consider ENOENT an error, and we want to return a |
| * negative dentry. |
| */ |
| if (err && err != -ENOENT) |
| goto out; |
| |
| /* instatiate a new negative dentry */ |
| dname.name = name->name; |
| dname.len = name->len; |
| |
| /* See if the low-level filesystem might want |
| * to use its own hash |
| */ |
| lower_dentry = d_hash_and_lookup(lower_dir_dentry, &dname); |
| if (IS_ERR(lower_dentry)) |
| return lower_dentry; |
| |
| if (!lower_dentry) { |
| /* We called vfs_path_lookup earlier, and did not get a negative |
| * dentry then. Don't confuse the lower filesystem by forcing |
| * one on it now... |
| */ |
| err = -ENOENT; |
| goto out; |
| } |
| |
| lower_path.dentry = lower_dentry; |
| lower_path.mnt = mntget(lower_dir_mnt); |
| sdcardfs_set_lower_path(dentry, &lower_path); |
| |
| /* |
| * If the intent is to create a file, then don't return an error, so |
| * the VFS will continue the process of making this negative dentry |
| * into a positive one. |
| */ |
| if (flags & (LOOKUP_CREATE|LOOKUP_RENAME_TARGET)) |
| err = 0; |
| |
| out: |
| if (err) |
| return ERR_PTR(err); |
| return ret_dentry; |
| } |
| |
| /* |
| * On success: |
| * fills dentry object appropriate values and returns NULL. |
| * On fail (== error) |
| * returns error ptr |
| * |
| * @dir : Parent inode. |
| * @dentry : Target dentry to lookup. we should set each of fields. |
| * (dentry->d_name is initialized already) |
| * @nd : nameidata of parent inode |
| */ |
| struct dentry *sdcardfs_lookup(struct inode *dir, struct dentry *dentry, |
| unsigned int flags) |
| { |
| struct dentry *ret = NULL, *parent; |
| struct path lower_parent_path; |
| int err = 0; |
| const struct cred *saved_cred = NULL; |
| |
| parent = dget_parent(dentry); |
| |
| if (!check_caller_access_to_name(d_inode(parent), &dentry->d_name)) { |
| ret = ERR_PTR(-EACCES); |
| goto out_err; |
| } |
| |
| /* save current_cred and override it */ |
| saved_cred = override_fsids(SDCARDFS_SB(dir->i_sb), |
| SDCARDFS_I(dir)->data); |
| if (!saved_cred) { |
| ret = ERR_PTR(-ENOMEM); |
| goto out_err; |
| } |
| |
| sdcardfs_get_lower_path(parent, &lower_parent_path); |
| |
| /* allocate dentry private data. We free it in ->d_release */ |
| err = new_dentry_private_data(dentry); |
| if (err) { |
| ret = ERR_PTR(err); |
| goto out; |
| } |
| |
| ret = __sdcardfs_lookup(dentry, flags, &lower_parent_path, |
| SDCARDFS_I(dir)->data->userid); |
| if (IS_ERR(ret)) |
| goto out; |
| if (ret) |
| dentry = ret; |
| if (d_inode(dentry)) { |
| fsstack_copy_attr_times(d_inode(dentry), |
| sdcardfs_lower_inode(d_inode(dentry))); |
| /* get derived permission */ |
| get_derived_permission(parent, dentry); |
| fixup_tmp_permissions(d_inode(dentry)); |
| fixup_lower_ownership(dentry, dentry->d_name.name); |
| } |
| /* update parent directory's atime */ |
| fsstack_copy_attr_atime(d_inode(parent), |
| sdcardfs_lower_inode(d_inode(parent))); |
| |
| out: |
| sdcardfs_put_lower_path(parent, &lower_parent_path); |
| revert_fsids(saved_cred); |
| out_err: |
| dput(parent); |
| return ret; |
| } |