![Linus Torvalds](/assets/img/avatar_default.png)
This bug could cause oopses and page state corruption, because ncpfs used the generic page-cache symlink handlign functions. But those functions only work if the page cache is guaranteed to be "stable", ie a page that was installed when the symlink walk was started has to still be installed in the page cache at the end of the walk. We could have fixed ncpfs to not use the generic helper routines, but it is in many ways much cleaner to instead improve on the symlink walking helper routines so that they don't require that absolute stability. We do this by allowing "follow_link()" to return a error-pointer as a cookie, which is fed back to the cleanup "put_link()" routine. This also simplifies NFS symlink handling. Signed-off-by: Linus Torvalds <torvalds@osdl.org>
339 lines
8.8 KiB
C
339 lines
8.8 KiB
C
/*
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* fs/cifs/link.c
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*
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* Copyright (C) International Business Machines Corp., 2002,2003
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* Author(s): Steve French (sfrench@us.ibm.com)
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*
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* This library is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published
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* by the Free Software Foundation; either version 2.1 of the License, or
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* (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
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* the GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/fs.h>
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#include <linux/stat.h>
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#include <linux/namei.h>
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#include "cifsfs.h"
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#include "cifspdu.h"
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#include "cifsglob.h"
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#include "cifsproto.h"
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#include "cifs_debug.h"
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#include "cifs_fs_sb.h"
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int
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cifs_hardlink(struct dentry *old_file, struct inode *inode,
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struct dentry *direntry)
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{
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int rc = -EACCES;
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int xid;
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char *fromName = NULL;
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char *toName = NULL;
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struct cifs_sb_info *cifs_sb_target;
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struct cifsTconInfo *pTcon;
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struct cifsInodeInfo *cifsInode;
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xid = GetXid();
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cifs_sb_target = CIFS_SB(inode->i_sb);
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pTcon = cifs_sb_target->tcon;
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/* No need to check for cross device links since server will do that
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BB note DFS case in future though (when we may have to check) */
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down(&inode->i_sb->s_vfs_rename_sem);
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fromName = build_path_from_dentry(old_file);
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toName = build_path_from_dentry(direntry);
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up(&inode->i_sb->s_vfs_rename_sem);
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if((fromName == NULL) || (toName == NULL)) {
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rc = -ENOMEM;
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goto cifs_hl_exit;
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}
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if (cifs_sb_target->tcon->ses->capabilities & CAP_UNIX)
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rc = CIFSUnixCreateHardLink(xid, pTcon, fromName, toName,
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cifs_sb_target->local_nls,
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cifs_sb_target->mnt_cifs_flags &
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CIFS_MOUNT_MAP_SPECIAL_CHR);
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else {
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rc = CIFSCreateHardLink(xid, pTcon, fromName, toName,
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cifs_sb_target->local_nls,
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cifs_sb_target->mnt_cifs_flags &
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CIFS_MOUNT_MAP_SPECIAL_CHR);
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if(rc == -EIO)
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rc = -EOPNOTSUPP;
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}
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/* if (!rc) */
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{
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/* renew_parental_timestamps(old_file);
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inode->i_nlink++;
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mark_inode_dirty(inode);
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d_instantiate(direntry, inode); */
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/* BB add call to either mark inode dirty or refresh its data and timestamp to current time */
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}
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d_drop(direntry); /* force new lookup from server */
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cifsInode = CIFS_I(old_file->d_inode);
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cifsInode->time = 0; /* will force revalidate to go get info when needed */
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cifs_hl_exit:
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if (fromName)
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kfree(fromName);
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if (toName)
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kfree(toName);
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FreeXid(xid);
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return rc;
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}
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void *
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cifs_follow_link(struct dentry *direntry, struct nameidata *nd)
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{
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struct inode *inode = direntry->d_inode;
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int rc = -EACCES;
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int xid;
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char *full_path = NULL;
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char * target_path = ERR_PTR(-ENOMEM);
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struct cifs_sb_info *cifs_sb;
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struct cifsTconInfo *pTcon;
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xid = GetXid();
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down(&direntry->d_sb->s_vfs_rename_sem);
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full_path = build_path_from_dentry(direntry);
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up(&direntry->d_sb->s_vfs_rename_sem);
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if (!full_path)
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goto out_no_free;
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cFYI(1, ("Full path: %s inode = 0x%p", full_path, inode));
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cifs_sb = CIFS_SB(inode->i_sb);
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pTcon = cifs_sb->tcon;
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target_path = kmalloc(PATH_MAX, GFP_KERNEL);
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if (!target_path) {
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target_path = ERR_PTR(-ENOMEM);
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goto out;
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}
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/* BB add read reparse point symlink code and Unix extensions symlink code here BB */
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if (pTcon->ses->capabilities & CAP_UNIX)
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rc = CIFSSMBUnixQuerySymLink(xid, pTcon, full_path,
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target_path,
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PATH_MAX-1,
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cifs_sb->local_nls);
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else {
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/* rc = CIFSSMBQueryReparseLinkInfo */
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/* BB Add code to Query ReparsePoint info */
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/* BB Add MAC style xsymlink check here if enabled */
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}
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if (rc == 0) {
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/* BB Add special case check for Samba DFS symlinks */
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target_path[PATH_MAX-1] = 0;
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} else {
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kfree(target_path);
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target_path = ERR_PTR(rc);
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}
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out:
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kfree(full_path);
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out_no_free:
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FreeXid(xid);
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nd_set_link(nd, target_path);
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return NULL; /* No cookie */
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}
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int
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cifs_symlink(struct inode *inode, struct dentry *direntry, const char *symname)
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{
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int rc = -EOPNOTSUPP;
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int xid;
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struct cifs_sb_info *cifs_sb;
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struct cifsTconInfo *pTcon;
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char *full_path = NULL;
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struct inode *newinode = NULL;
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xid = GetXid();
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cifs_sb = CIFS_SB(inode->i_sb);
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pTcon = cifs_sb->tcon;
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down(&inode->i_sb->s_vfs_rename_sem);
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full_path = build_path_from_dentry(direntry);
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up(&inode->i_sb->s_vfs_rename_sem);
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if(full_path == NULL) {
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FreeXid(xid);
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return -ENOMEM;
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}
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cFYI(1, ("Full path: %s ", full_path));
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cFYI(1, ("symname is %s", symname));
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/* BB what if DFS and this volume is on different share? BB */
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if (cifs_sb->tcon->ses->capabilities & CAP_UNIX)
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rc = CIFSUnixCreateSymLink(xid, pTcon, full_path, symname,
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cifs_sb->local_nls);
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/* else
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rc = CIFSCreateReparseSymLink(xid, pTcon, fromName, toName,cifs_sb_target->local_nls); */
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if (rc == 0) {
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if (pTcon->ses->capabilities & CAP_UNIX)
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rc = cifs_get_inode_info_unix(&newinode, full_path,
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inode->i_sb,xid);
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else
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rc = cifs_get_inode_info(&newinode, full_path, NULL,
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inode->i_sb,xid);
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if (rc != 0) {
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cFYI(1,
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("Create symlink worked but get_inode_info failed with rc = %d ",
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rc));
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} else {
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direntry->d_op = &cifs_dentry_ops;
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d_instantiate(direntry, newinode);
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}
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}
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if (full_path)
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kfree(full_path);
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FreeXid(xid);
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return rc;
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}
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int
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cifs_readlink(struct dentry *direntry, char __user *pBuffer, int buflen)
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{
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struct inode *inode = direntry->d_inode;
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int rc = -EACCES;
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int xid;
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int oplock = FALSE;
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struct cifs_sb_info *cifs_sb;
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struct cifsTconInfo *pTcon;
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char *full_path = NULL;
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char *tmp_path = NULL;
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char * tmpbuffer;
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unsigned char * referrals = NULL;
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int num_referrals = 0;
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int len;
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__u16 fid;
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xid = GetXid();
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cifs_sb = CIFS_SB(inode->i_sb);
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pTcon = cifs_sb->tcon;
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/* BB would it be safe against deadlock to grab this sem
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even though rename itself grabs the sem and calls lookup? */
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/* down(&inode->i_sb->s_vfs_rename_sem);*/
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full_path = build_path_from_dentry(direntry);
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/* up(&inode->i_sb->s_vfs_rename_sem);*/
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if(full_path == NULL) {
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FreeXid(xid);
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return -ENOMEM;
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}
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cFYI(1,
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("Full path: %s inode = 0x%p pBuffer = 0x%p buflen = %d",
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full_path, inode, pBuffer, buflen));
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if(buflen > PATH_MAX)
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len = PATH_MAX;
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else
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len = buflen;
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tmpbuffer = kmalloc(len,GFP_KERNEL);
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if(tmpbuffer == NULL) {
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if (full_path)
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kfree(full_path);
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FreeXid(xid);
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return -ENOMEM;
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}
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/* BB add read reparse point symlink code and Unix extensions symlink code here BB */
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if (cifs_sb->tcon->ses->capabilities & CAP_UNIX)
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rc = CIFSSMBUnixQuerySymLink(xid, pTcon, full_path,
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tmpbuffer,
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len - 1,
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cifs_sb->local_nls);
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else {
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rc = CIFSSMBOpen(xid, pTcon, full_path, FILE_OPEN, GENERIC_READ,
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OPEN_REPARSE_POINT,&fid, &oplock, NULL,
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cifs_sb->local_nls,
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cifs_sb->mnt_cifs_flags &
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CIFS_MOUNT_MAP_SPECIAL_CHR);
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if(!rc) {
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rc = CIFSSMBQueryReparseLinkInfo(xid, pTcon, full_path,
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tmpbuffer,
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len - 1,
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fid,
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cifs_sb->local_nls);
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if(CIFSSMBClose(xid, pTcon, fid)) {
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cFYI(1,("Error closing junction point (open for ioctl)"));
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}
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if(rc == -EIO) {
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/* Query if DFS Junction */
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tmp_path =
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kmalloc(MAX_TREE_SIZE + MAX_PATHCONF + 1,
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GFP_KERNEL);
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if (tmp_path) {
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strncpy(tmp_path, pTcon->treeName, MAX_TREE_SIZE);
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strncat(tmp_path, full_path, MAX_PATHCONF);
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rc = get_dfs_path(xid, pTcon->ses, tmp_path,
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cifs_sb->local_nls,
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&num_referrals, &referrals,
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cifs_sb->mnt_cifs_flags &
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CIFS_MOUNT_MAP_SPECIAL_CHR);
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cFYI(1,("Get DFS for %s rc = %d ",tmp_path, rc));
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if((num_referrals == 0) && (rc == 0))
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rc = -EACCES;
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else {
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cFYI(1,("num referral: %d",num_referrals));
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if(referrals) {
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cFYI(1,("referral string: %s ",referrals));
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strncpy(tmpbuffer, referrals, len-1);
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}
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}
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if(referrals)
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kfree(referrals);
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kfree(tmp_path);
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}
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/* BB add code like else decode referrals then memcpy to
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tmpbuffer and free referrals string array BB */
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}
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}
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}
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/* BB Anything else to do to handle recursive links? */
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/* BB Should we be using page ops here? */
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/* BB null terminate returned string in pBuffer? BB */
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if (rc == 0) {
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rc = vfs_readlink(direntry, pBuffer, len, tmpbuffer);
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cFYI(1,
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("vfs_readlink called from cifs_readlink returned %d",
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rc));
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}
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if (tmpbuffer) {
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kfree(tmpbuffer);
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}
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if (full_path) {
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kfree(full_path);
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}
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FreeXid(xid);
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return rc;
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}
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void cifs_put_link(struct dentry *direntry, struct nameidata *nd, void *cookie)
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{
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char *p = nd_get_link(nd);
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if (!IS_ERR(p))
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kfree(p);
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}
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