diff options
Diffstat (limited to 'fs/ntfs/namei.c')
| -rw-r--r-- | fs/ntfs/namei.c | 498 |
1 files changed, 498 insertions, 0 deletions
diff --git a/fs/ntfs/namei.c b/fs/ntfs/namei.c new file mode 100644 index 000000000000..7c7e13b43b2e --- /dev/null +++ b/fs/ntfs/namei.c @@ -0,0 +1,498 @@ +/* + * namei.c - NTFS kernel directory inode operations. Part of the Linux-NTFS + * project. + * + * Copyright (c) 2001-2004 Anton Altaparmakov + * + * This program/include file 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. + * + * This program/include file is distributed in the hope that it will be + * useful, but WITHOUT ANY WARRANTY; without even the implied warranty + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program (in the main directory of the Linux-NTFS + * distribution in the file COPYING); if not, write to the Free Software + * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#include <linux/dcache.h> +#include <linux/security.h> + +#include "attrib.h" +#include "debug.h" +#include "dir.h" +#include "mft.h" +#include "ntfs.h" + +/** + * ntfs_lookup - find the inode represented by a dentry in a directory inode + * @dir_ino: directory inode in which to look for the inode + * @dent: dentry representing the inode to look for + * @nd: lookup nameidata + * + * In short, ntfs_lookup() looks for the inode represented by the dentry @dent + * in the directory inode @dir_ino and if found attaches the inode to the + * dentry @dent. + * + * In more detail, the dentry @dent specifies which inode to look for by + * supplying the name of the inode in @dent->d_name.name. ntfs_lookup() + * converts the name to Unicode and walks the contents of the directory inode + * @dir_ino looking for the converted Unicode name. If the name is found in the + * directory, the corresponding inode is loaded by calling ntfs_iget() on its + * inode number and the inode is associated with the dentry @dent via a call to + * d_splice_alias(). + * + * If the name is not found in the directory, a NULL inode is inserted into the + * dentry @dent via a call to d_add(). The dentry is then termed a negative + * dentry. + * + * Only if an actual error occurs, do we return an error via ERR_PTR(). + * + * In order to handle the case insensitivity issues of NTFS with regards to the + * dcache and the dcache requiring only one dentry per directory, we deal with + * dentry aliases that only differ in case in ->ntfs_lookup() while maintaining + * a case sensitive dcache. This means that we get the full benefit of dcache + * speed when the file/directory is looked up with the same case as returned by + * ->ntfs_readdir() but that a lookup for any other case (or for the short file + * name) will not find anything in dcache and will enter ->ntfs_lookup() + * instead, where we search the directory for a fully matching file name + * (including case) and if that is not found, we search for a file name that + * matches with different case and if that has non-POSIX semantics we return + * that. We actually do only one search (case sensitive) and keep tabs on + * whether we have found a case insensitive match in the process. + * + * To simplify matters for us, we do not treat the short vs long filenames as + * two hard links but instead if the lookup matches a short filename, we + * return the dentry for the corresponding long filename instead. + * + * There are three cases we need to distinguish here: + * + * 1) @dent perfectly matches (i.e. including case) a directory entry with a + * file name in the WIN32 or POSIX namespaces. In this case + * ntfs_lookup_inode_by_name() will return with name set to NULL and we + * just d_splice_alias() @dent. + * 2) @dent matches (not including case) a directory entry with a file name in + * the WIN32 namespace. In this case ntfs_lookup_inode_by_name() will return + * with name set to point to a kmalloc()ed ntfs_name structure containing + * the properly cased little endian Unicode name. We convert the name to the + * current NLS code page, search if a dentry with this name already exists + * and if so return that instead of @dent. At this point things are + * complicated by the possibility of 'disconnected' dentries due to NFS + * which we deal with appropriately (see the code comments). The VFS will + * then destroy the old @dent and use the one we returned. If a dentry is + * not found, we allocate a new one, d_splice_alias() it, and return it as + * above. + * 3) @dent matches either perfectly or not (i.e. we don't care about case) a + * directory entry with a file name in the DOS namespace. In this case + * ntfs_lookup_inode_by_name() will return with name set to point to a + * kmalloc()ed ntfs_name structure containing the mft reference (cpu endian) + * of the inode. We use the mft reference to read the inode and to find the + * file name in the WIN32 namespace corresponding to the matched short file + * name. We then convert the name to the current NLS code page, and proceed + * searching for a dentry with this name, etc, as in case 2), above. + * + * Locking: Caller must hold i_sem on the directory. + */ +static struct dentry *ntfs_lookup(struct inode *dir_ino, struct dentry *dent, + struct nameidata *nd) +{ + ntfs_volume *vol = NTFS_SB(dir_ino->i_sb); + struct inode *dent_inode; + ntfschar *uname; + ntfs_name *name = NULL; + MFT_REF mref; + unsigned long dent_ino; + int uname_len; + + ntfs_debug("Looking up %s in directory inode 0x%lx.", + dent->d_name.name, dir_ino->i_ino); + /* Convert the name of the dentry to Unicode. */ + uname_len = ntfs_nlstoucs(vol, dent->d_name.name, dent->d_name.len, + &uname); + if (uname_len < 0) { + ntfs_error(vol->sb, "Failed to convert name to Unicode."); + return ERR_PTR(uname_len); + } + mref = ntfs_lookup_inode_by_name(NTFS_I(dir_ino), uname, uname_len, + &name); + kmem_cache_free(ntfs_name_cache, uname); + if (!IS_ERR_MREF(mref)) { + dent_ino = MREF(mref); + ntfs_debug("Found inode 0x%lx. Calling ntfs_iget.", dent_ino); + dent_inode = ntfs_iget(vol->sb, dent_ino); + if (likely(!IS_ERR(dent_inode))) { + /* Consistency check. */ + if (is_bad_inode(dent_inode) || MSEQNO(mref) == + NTFS_I(dent_inode)->seq_no || + dent_ino == FILE_MFT) { + /* Perfect WIN32/POSIX match. -- Case 1. */ + if (!name) { + ntfs_debug("Done. (Case 1.)"); + return d_splice_alias(dent_inode, dent); + } + /* + * We are too indented. Handle imperfect + * matches and short file names further below. + */ + goto handle_name; + } + ntfs_error(vol->sb, "Found stale reference to inode " + "0x%lx (reference sequence number = " + "0x%x, inode sequence number = 0x%x), " + "returning -EIO. Run chkdsk.", + dent_ino, MSEQNO(mref), + NTFS_I(dent_inode)->seq_no); + iput(dent_inode); + dent_inode = ERR_PTR(-EIO); + } else + ntfs_error(vol->sb, "ntfs_iget(0x%lx) failed with " + "error code %li.", dent_ino, + PTR_ERR(dent_inode)); + if (name) + kfree(name); + /* Return the error code. */ + return (struct dentry *)dent_inode; + } + /* It is guaranteed that name is no longer allocated at this point. */ + if (MREF_ERR(mref) == -ENOENT) { + ntfs_debug("Entry was not found, adding negative dentry."); + /* The dcache will handle negative entries. */ + d_add(dent, NULL); + ntfs_debug("Done."); + return NULL; + } + ntfs_error(vol->sb, "ntfs_lookup_ino_by_name() failed with error " + "code %i.", -MREF_ERR(mref)); + return ERR_PTR(MREF_ERR(mref)); + + // TODO: Consider moving this lot to a separate function! (AIA) +handle_name: + { + struct dentry *real_dent, *new_dent; + MFT_RECORD *m; + ntfs_attr_search_ctx *ctx; + ntfs_inode *ni = NTFS_I(dent_inode); + int err; + struct qstr nls_name; + + nls_name.name = NULL; + if (name->type != FILE_NAME_DOS) { /* Case 2. */ + ntfs_debug("Case 2."); + nls_name.len = (unsigned)ntfs_ucstonls(vol, + (ntfschar*)&name->name, name->len, + (unsigned char**)&nls_name.name, 0); + kfree(name); + } else /* if (name->type == FILE_NAME_DOS) */ { /* Case 3. */ + FILE_NAME_ATTR *fn; + + ntfs_debug("Case 3."); + kfree(name); + + /* Find the WIN32 name corresponding to the matched DOS name. */ + ni = NTFS_I(dent_inode); + m = map_mft_record(ni); + if (IS_ERR(m)) { + err = PTR_ERR(m); + m = NULL; + ctx = NULL; + goto err_out; + } + ctx = ntfs_attr_get_search_ctx(ni, m); + if (unlikely(!ctx)) { + err = -ENOMEM; + goto err_out; + } + do { + ATTR_RECORD *a; + u32 val_len; + + err = ntfs_attr_lookup(AT_FILE_NAME, NULL, 0, 0, 0, + NULL, 0, ctx); + if (unlikely(err)) { + ntfs_error(vol->sb, "Inode corrupt: No WIN32 " + "namespace counterpart to DOS " + "file name. Run chkdsk."); + if (err == -ENOENT) + err = -EIO; + goto err_out; + } + /* Consistency checks. */ + a = ctx->attr; + if (a->non_resident || a->flags) + goto eio_err_out; + val_len = le32_to_cpu(a->data.resident.value_length); + if (le16_to_cpu(a->data.resident.value_offset) + + val_len > le32_to_cpu(a->length)) + goto eio_err_out; + fn = (FILE_NAME_ATTR*)((u8*)ctx->attr + le16_to_cpu( + ctx->attr->data.resident.value_offset)); + if ((u32)(fn->file_name_length * sizeof(ntfschar) + + sizeof(FILE_NAME_ATTR)) > val_len) + goto eio_err_out; + } while (fn->file_name_type != FILE_NAME_WIN32); + + /* Convert the found WIN32 name to current NLS code page. */ + nls_name.len = (unsigned)ntfs_ucstonls(vol, + (ntfschar*)&fn->file_name, fn->file_name_length, + (unsigned char**)&nls_name.name, 0); + + ntfs_attr_put_search_ctx(ctx); + unmap_mft_record(ni); + } + m = NULL; + ctx = NULL; + + /* Check if a conversion error occurred. */ + if ((signed)nls_name.len < 0) { + err = (signed)nls_name.len; + goto err_out; + } + nls_name.hash = full_name_hash(nls_name.name, nls_name.len); + + /* + * Note: No need for dent->d_lock lock as i_sem is held on the + * parent inode. + */ + + /* Does a dentry matching the nls_name exist already? */ + real_dent = d_lookup(dent->d_parent, &nls_name); + /* If not, create it now. */ + if (!real_dent) { + real_dent = d_alloc(dent->d_parent, &nls_name); + kfree(nls_name.name); + if (!real_dent) { + err = -ENOMEM; + goto err_out; + } + new_dent = d_splice_alias(dent_inode, real_dent); + if (new_dent) + dput(real_dent); + else + new_dent = real_dent; + ntfs_debug("Done. (Created new dentry.)"); + return new_dent; + } + kfree(nls_name.name); + /* Matching dentry exists, check if it is negative. */ + if (real_dent->d_inode) { + if (unlikely(real_dent->d_inode != dent_inode)) { + /* This can happen because bad inodes are unhashed. */ + BUG_ON(!is_bad_inode(dent_inode)); + BUG_ON(!is_bad_inode(real_dent->d_inode)); + } + /* + * Already have the inode and the dentry attached, decrement + * the reference count to balance the ntfs_iget() we did + * earlier on. We found the dentry using d_lookup() so it + * cannot be disconnected and thus we do not need to worry + * about any NFS/disconnectedness issues here. + */ + iput(dent_inode); + ntfs_debug("Done. (Already had inode and dentry.)"); + return real_dent; + } + /* + * Negative dentry: instantiate it unless the inode is a directory and + * has a 'disconnected' dentry (i.e. IS_ROOT and DCACHE_DISCONNECTED), + * in which case d_move() that in place of the found dentry. + */ + if (!S_ISDIR(dent_inode->i_mode)) { + /* Not a directory; everything is easy. */ + d_instantiate(real_dent, dent_inode); + ntfs_debug("Done. (Already had negative file dentry.)"); + return real_dent; + } + spin_lock(&dcache_lock); + if (list_empty(&dent_inode->i_dentry)) { + /* + * Directory without a 'disconnected' dentry; we need to do + * d_instantiate() by hand because it takes dcache_lock which + * we already hold. + */ + list_add(&real_dent->d_alias, &dent_inode->i_dentry); + real_dent->d_inode = dent_inode; + spin_unlock(&dcache_lock); + security_d_instantiate(real_dent, dent_inode); + ntfs_debug("Done. (Already had negative directory dentry.)"); + return real_dent; + } + /* + * Directory with a 'disconnected' dentry; get a reference to the + * 'disconnected' dentry. + */ + new_dent = list_entry(dent_inode->i_dentry.next, struct dentry, + d_alias); + dget_locked(new_dent); + spin_unlock(&dcache_lock); + /* Do security vodoo. */ + security_d_instantiate(real_dent, dent_inode); + /* Move new_dent in place of real_dent. */ + d_move(new_dent, real_dent); + /* Balance the ntfs_iget() we did above. */ + iput(dent_inode); + /* Throw away real_dent. */ + dput(real_dent); + /* Use new_dent as the actual dentry. */ + ntfs_debug("Done. (Already had negative, disconnected directory " + "dentry.)"); + return new_dent; + +eio_err_out: + ntfs_error(vol->sb, "Illegal file name attribute. Run chkdsk."); + err = -EIO; +err_out: + if (ctx) + ntfs_attr_put_search_ctx(ctx); + if (m) + unmap_mft_record(ni); + iput(dent_inode); + ntfs_error(vol->sb, "Failed, returning error code %i.", err); + return ERR_PTR(err); + } +} + +/** + * Inode operations for directories. + */ +struct inode_operations ntfs_dir_inode_ops = { + .lookup = ntfs_lookup, /* VFS: Lookup directory. */ +}; + +/** + * ntfs_get_parent - find the dentry of the parent of a given directory dentry + * @child_dent: dentry of the directory whose parent directory to find + * + * Find the dentry for the parent directory of the directory specified by the + * dentry @child_dent. This function is called from + * fs/exportfs/expfs.c::find_exported_dentry() which in turn is called from the + * default ->decode_fh() which is export_decode_fh() in the same file. + * + * The code is based on the ext3 ->get_parent() implementation found in + * fs/ext3/namei.c::ext3_get_parent(). + * + * Note: ntfs_get_parent() is called with @child_dent->d_inode->i_sem down. + * + * Return the dentry of the parent directory on success or the error code on + * error (IS_ERR() is true). + */ +struct dentry *ntfs_get_parent(struct dentry *child_dent) +{ + struct inode *vi = child_dent->d_inode; + ntfs_inode *ni = NTFS_I(vi); + MFT_RECORD *mrec; + ntfs_attr_search_ctx *ctx; + ATTR_RECORD *attr; + FILE_NAME_ATTR *fn; + struct inode *parent_vi; + struct dentry *parent_dent; + unsigned long parent_ino; + int err; + + ntfs_debug("Entering for inode 0x%lx.", vi->i_ino); + /* Get the mft record of the inode belonging to the child dentry. */ + mrec = map_mft_record(ni); + if (IS_ERR(mrec)) + return (struct dentry *)mrec; + /* Find the first file name attribute in the mft record. */ + ctx = ntfs_attr_get_search_ctx(ni, mrec); + if (unlikely(!ctx)) { + unmap_mft_record(ni); + return ERR_PTR(-ENOMEM); + } +try_next: + err = ntfs_attr_lookup(AT_FILE_NAME, NULL, 0, CASE_SENSITIVE, 0, NULL, + 0, ctx); + if (unlikely(err)) { + ntfs_attr_put_search_ctx(ctx); + unmap_mft_record(ni); + if (err == -ENOENT) + ntfs_error(vi->i_sb, "Inode 0x%lx does not have a " + "file name attribute. Run chkdsk.", + vi->i_ino); + return ERR_PTR(err); + } + attr = ctx->attr; + if (unlikely(attr->non_resident)) + goto try_next; + fn = (FILE_NAME_ATTR *)((u8 *)attr + + le16_to_cpu(attr->data.resident.value_offset)); + if (unlikely((u8 *)fn + le32_to_cpu(attr->data.resident.value_length) > + (u8*)attr + le32_to_cpu(attr->length))) + goto try_next; + /* Get the inode number of the parent directory. */ + parent_ino = MREF_LE(fn->parent_directory); + /* Release the search context and the mft record of the child. */ + ntfs_attr_put_search_ctx(ctx); + unmap_mft_record(ni); + /* Get the inode of the parent directory. */ + parent_vi = ntfs_iget(vi->i_sb, parent_ino); + if (IS_ERR(parent_vi) || unlikely(is_bad_inode(parent_vi))) { + if (!IS_ERR(parent_vi)) + iput(parent_vi); + ntfs_error(vi->i_sb, "Failed to get parent directory inode " + "0x%lx of child inode 0x%lx.", parent_ino, + vi->i_ino); + return ERR_PTR(-EACCES); + } + /* Finally get a dentry for the parent directory and return it. */ + parent_dent = d_alloc_anon(parent_vi); + if (unlikely(!parent_dent)) { + iput(parent_vi); + return ERR_PTR(-ENOMEM); + } + ntfs_debug("Done for inode 0x%lx.", vi->i_ino); + return parent_dent; +} + +/** + * ntfs_get_dentry - find a dentry for the inode from a file handle sub-fragment + * @sb: super block identifying the mounted ntfs volume + * @fh: the file handle sub-fragment + * + * Find a dentry for the inode given a file handle sub-fragment. This function + * is called from fs/exportfs/expfs.c::find_exported_dentry() which in turn is + * called from the default ->decode_fh() which is export_decode_fh() in the + * same file. The code is closely based on the default ->get_dentry() helper + * fs/exportfs/expfs.c::get_object(). + * + * The @fh contains two 32-bit unsigned values, the first one is the inode + * number and the second one is the inode generation. + * + * Return the dentry on success or the error code on error (IS_ERR() is true). + */ +struct dentry *ntfs_get_dentry(struct super_block *sb, void *fh) +{ + struct inode *vi; + struct dentry *dent; + unsigned long ino = ((u32 *)fh)[0]; + u32 gen = ((u32 *)fh)[1]; + + ntfs_debug("Entering for inode 0x%lx, generation 0x%x.", ino, gen); + vi = ntfs_iget(sb, ino); + if (IS_ERR(vi)) { + ntfs_error(sb, "Failed to get inode 0x%lx.", ino); + return (struct dentry *)vi; + } + if (unlikely(is_bad_inode(vi) || vi->i_generation != gen)) { + /* We didn't find the right inode. */ + ntfs_error(sb, "Inode 0x%lx, bad count: %d %d or version 0x%x " + "0x%x.", vi->i_ino, vi->i_nlink, + atomic_read(&vi->i_count), vi->i_generation, + gen); + iput(vi); + return ERR_PTR(-ESTALE); + } + /* Now find a dentry. If possible, get a well-connected one. */ + dent = d_alloc_anon(vi); + if (unlikely(!dent)) { + iput(vi); + return ERR_PTR(-ENOMEM); + } + ntfs_debug("Done for inode 0x%lx, generation 0x%x.", ino, gen); + return dent; +} |