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-rw-r--r--fs/ntfs/namei.c498
1 files changed, 498 insertions, 0 deletions
diff --git a/fs/ntfs/namei.c b/fs/ntfs/namei.c
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+++ b/fs/ntfs/namei.c
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+/*
+ * 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;
+}
generated by cgit v1.2.3-18-g5258 (git 2.32.0) at 2024-11-23 18:34:26 +0000