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linux-next/fs/cifs/link.c
Ronnie Sahlberg ebaf546a55 SMB3: Clean up query symlink when reparse point 
Two of the common symlink formats use reparse points
(unlike mfsymlinks and also unlike the SMB1 posix
extensions).  This is the first part of the fixes
to allow these reparse points (NFS style and Windows
symlinks) to be resolved properly as symlinks by the
client.

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
2019-05-07 23:24:55 -05:00

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/*
* fs/cifs/link.c
*
* Copyright (C) International Business Machines Corp., 2002,2008
* Author(s): Steve French (sfrench@us.ibm.com)
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/fs.h>
#include <linux/stat.h>
#include <linux/slab.h>
#include <linux/namei.h>
#include "cifsfs.h"
#include "cifspdu.h"
#include "cifsglob.h"
#include "cifsproto.h"
#include "cifs_debug.h"
#include "cifs_fs_sb.h"
#include "cifs_unicode.h"
#include "smb2proto.h"
/*
* M-F Symlink Functions - Begin
*/
#define CIFS_MF_SYMLINK_LEN_OFFSET (4+1)
#define CIFS_MF_SYMLINK_MD5_OFFSET (CIFS_MF_SYMLINK_LEN_OFFSET+(4+1))
#define CIFS_MF_SYMLINK_LINK_OFFSET (CIFS_MF_SYMLINK_MD5_OFFSET+(32+1))
#define CIFS_MF_SYMLINK_LINK_MAXLEN (1024)
#define CIFS_MF_SYMLINK_FILE_SIZE \
(CIFS_MF_SYMLINK_LINK_OFFSET + CIFS_MF_SYMLINK_LINK_MAXLEN)
#define CIFS_MF_SYMLINK_LEN_FORMAT "XSym\n%04u\n"
#define CIFS_MF_SYMLINK_MD5_FORMAT "%16phN\n"
#define CIFS_MF_SYMLINK_MD5_ARGS(md5_hash) md5_hash
static int
symlink_hash(unsigned int link_len, const char *link_str, u8 *md5_hash)
{
int rc;
struct crypto_shash *md5 = NULL;
struct sdesc *sdescmd5 = NULL;
rc = cifs_alloc_hash("md5", &md5, &sdescmd5);
if (rc)
goto symlink_hash_err;
rc = crypto_shash_init(&sdescmd5->shash);
if (rc) {
cifs_dbg(VFS, "%s: Could not init md5 shash\n", __func__);
goto symlink_hash_err;
}
rc = crypto_shash_update(&sdescmd5->shash, link_str, link_len);
if (rc) {
cifs_dbg(VFS, "%s: Could not update with link_str\n", __func__);
goto symlink_hash_err;
}
rc = crypto_shash_final(&sdescmd5->shash, md5_hash);
if (rc)
cifs_dbg(VFS, "%s: Could not generate md5 hash\n", __func__);
symlink_hash_err:
cifs_free_hash(&md5, &sdescmd5);
return rc;
}
static int
parse_mf_symlink(const u8 *buf, unsigned int buf_len, unsigned int *_link_len,
char **_link_str)
{
int rc;
unsigned int link_len;
const char *md5_str1;
const char *link_str;
u8 md5_hash[16];
char md5_str2[34];
if (buf_len != CIFS_MF_SYMLINK_FILE_SIZE)
return -EINVAL;
md5_str1 = (const char *)&buf[CIFS_MF_SYMLINK_MD5_OFFSET];
link_str = (const char *)&buf[CIFS_MF_SYMLINK_LINK_OFFSET];
rc = sscanf(buf, CIFS_MF_SYMLINK_LEN_FORMAT, &link_len);
if (rc != 1)
return -EINVAL;
rc = symlink_hash(link_len, link_str, md5_hash);
if (rc) {
cifs_dbg(FYI, "%s: MD5 hash failure: %d\n", __func__, rc);
return rc;
}
scnprintf(md5_str2, sizeof(md5_str2),
CIFS_MF_SYMLINK_MD5_FORMAT,
CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));
if (strncmp(md5_str1, md5_str2, 17) != 0)
return -EINVAL;
if (_link_str) {
*_link_str = kstrndup(link_str, link_len, GFP_KERNEL);
if (!*_link_str)
return -ENOMEM;
}
*_link_len = link_len;
return 0;
}
static int
format_mf_symlink(u8 *buf, unsigned int buf_len, const char *link_str)
{
int rc;
unsigned int link_len;
unsigned int ofs;
u8 md5_hash[16];
if (buf_len != CIFS_MF_SYMLINK_FILE_SIZE)
return -EINVAL;
link_len = strlen(link_str);
if (link_len > CIFS_MF_SYMLINK_LINK_MAXLEN)
return -ENAMETOOLONG;
rc = symlink_hash(link_len, link_str, md5_hash);
if (rc) {
cifs_dbg(FYI, "%s: MD5 hash failure: %d\n", __func__, rc);
return rc;
}
scnprintf(buf, buf_len,
CIFS_MF_SYMLINK_LEN_FORMAT CIFS_MF_SYMLINK_MD5_FORMAT,
link_len,
CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));
ofs = CIFS_MF_SYMLINK_LINK_OFFSET;
memcpy(buf + ofs, link_str, link_len);
ofs += link_len;
if (ofs < CIFS_MF_SYMLINK_FILE_SIZE) {
buf[ofs] = '\n';
ofs++;
}
while (ofs < CIFS_MF_SYMLINK_FILE_SIZE) {
buf[ofs] = ' ';
ofs++;
}
return 0;
}
bool
couldbe_mf_symlink(const struct cifs_fattr *fattr)
{
if (!S_ISREG(fattr->cf_mode))
/* it's not a symlink */
return false;
if (fattr->cf_eof != CIFS_MF_SYMLINK_FILE_SIZE)
/* it's not a symlink */
return false;
return true;
}
static int
create_mf_symlink(const unsigned int xid, struct cifs_tcon *tcon,
struct cifs_sb_info *cifs_sb, const char *fromName,
const char *toName)
{
int rc;
u8 *buf;
unsigned int bytes_written = 0;
buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
if (!buf)
return -ENOMEM;
rc = format_mf_symlink(buf, CIFS_MF_SYMLINK_FILE_SIZE, toName);
if (rc)
goto out;
if (tcon->ses->server->ops->create_mf_symlink)
rc = tcon->ses->server->ops->create_mf_symlink(xid, tcon,
cifs_sb, fromName, buf, &bytes_written);
else
rc = -EOPNOTSUPP;
if (rc)
goto out;
if (bytes_written != CIFS_MF_SYMLINK_FILE_SIZE)
rc = -EIO;
out:
kfree(buf);
return rc;
}
static int
query_mf_symlink(const unsigned int xid, struct cifs_tcon *tcon,
struct cifs_sb_info *cifs_sb, const unsigned char *path,
char **symlinkinfo)
{
int rc;
u8 *buf = NULL;
unsigned int link_len = 0;
unsigned int bytes_read = 0;
buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
if (!buf)
return -ENOMEM;
if (tcon->ses->server->ops->query_mf_symlink)
rc = tcon->ses->server->ops->query_mf_symlink(xid, tcon,
cifs_sb, path, buf, &bytes_read);
else
rc = -ENOSYS;
if (rc)
goto out;
if (bytes_read == 0) { /* not a symlink */
rc = -EINVAL;
goto out;
}
rc = parse_mf_symlink(buf, bytes_read, &link_len, symlinkinfo);
out:
kfree(buf);
return rc;
}
int
check_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
struct cifs_sb_info *cifs_sb, struct cifs_fattr *fattr,
const unsigned char *path)
{
int rc;
u8 *buf = NULL;
unsigned int link_len = 0;
unsigned int bytes_read = 0;
if (!couldbe_mf_symlink(fattr))
/* it's not a symlink */
return 0;
buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
if (!buf)
return -ENOMEM;
if (tcon->ses->server->ops->query_mf_symlink)
rc = tcon->ses->server->ops->query_mf_symlink(xid, tcon,
cifs_sb, path, buf, &bytes_read);
else
rc = -ENOSYS;
if (rc)
goto out;
if (bytes_read == 0) /* not a symlink */
goto out;
rc = parse_mf_symlink(buf, bytes_read, &link_len, NULL);
if (rc == -EINVAL) {
/* it's not a symlink */
rc = 0;
goto out;
}
if (rc != 0)
goto out;
/* it is a symlink */
fattr->cf_eof = link_len;
fattr->cf_mode &= ~S_IFMT;
fattr->cf_mode |= S_IFLNK | S_IRWXU | S_IRWXG | S_IRWXO;
fattr->cf_dtype = DT_LNK;
out:
kfree(buf);
return rc;
}
/*
* SMB 1.0 Protocol specific functions
*/
int
cifs_query_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
struct cifs_sb_info *cifs_sb, const unsigned char *path,
char *pbuf, unsigned int *pbytes_read)
{
int rc;
int oplock = 0;
struct cifs_fid fid;
struct cifs_open_parms oparms;
struct cifs_io_parms io_parms;
int buf_type = CIFS_NO_BUFFER;
FILE_ALL_INFO file_info;
oparms.tcon = tcon;
oparms.cifs_sb = cifs_sb;
oparms.desired_access = GENERIC_READ;
oparms.create_options = CREATE_NOT_DIR;
oparms.disposition = FILE_OPEN;
oparms.path = path;
oparms.fid = &fid;
oparms.reconnect = false;
rc = CIFS_open(xid, &oparms, &oplock, &file_info);
if (rc)
return rc;
if (file_info.EndOfFile != cpu_to_le64(CIFS_MF_SYMLINK_FILE_SIZE)) {
rc = -ENOENT;
/* it's not a symlink */
goto out;
}
io_parms.netfid = fid.netfid;
io_parms.pid = current->tgid;
io_parms.tcon = tcon;
io_parms.offset = 0;
io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
rc = CIFSSMBRead(xid, &io_parms, pbytes_read, &pbuf, &buf_type);
out:
CIFSSMBClose(xid, tcon, fid.netfid);
return rc;
}
int
cifs_create_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
struct cifs_sb_info *cifs_sb, const unsigned char *path,
char *pbuf, unsigned int *pbytes_written)
{
int rc;
int oplock = 0;
struct cifs_fid fid;
struct cifs_open_parms oparms;
struct cifs_io_parms io_parms;
int create_options = CREATE_NOT_DIR;
if (backup_cred(cifs_sb))
create_options |= CREATE_OPEN_BACKUP_INTENT;
oparms.tcon = tcon;
oparms.cifs_sb = cifs_sb;
oparms.desired_access = GENERIC_WRITE;
oparms.create_options = create_options;
oparms.disposition = FILE_CREATE;
oparms.path = path;
oparms.fid = &fid;
oparms.reconnect = false;
rc = CIFS_open(xid, &oparms, &oplock, NULL);
if (rc)
return rc;
io_parms.netfid = fid.netfid;
io_parms.pid = current->tgid;
io_parms.tcon = tcon;
io_parms.offset = 0;
io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
rc = CIFSSMBWrite(xid, &io_parms, pbytes_written, pbuf);
CIFSSMBClose(xid, tcon, fid.netfid);
return rc;
}
/*
* SMB 2.1/SMB3 Protocol specific functions
*/
int
smb3_query_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
struct cifs_sb_info *cifs_sb, const unsigned char *path,
char *pbuf, unsigned int *pbytes_read)
{
int rc;
struct cifs_fid fid;
struct cifs_open_parms oparms;
struct cifs_io_parms io_parms;
int buf_type = CIFS_NO_BUFFER;
__le16 *utf16_path;
__u8 oplock = SMB2_OPLOCK_LEVEL_NONE;
struct smb2_file_all_info *pfile_info = NULL;
oparms.tcon = tcon;
oparms.cifs_sb = cifs_sb;
oparms.desired_access = GENERIC_READ;
oparms.create_options = CREATE_NOT_DIR;
if (backup_cred(cifs_sb))
oparms.create_options |= CREATE_OPEN_BACKUP_INTENT;
oparms.disposition = FILE_OPEN;
oparms.fid = &fid;
oparms.reconnect = false;
utf16_path = cifs_convert_path_to_utf16(path, cifs_sb);
if (utf16_path == NULL)
return -ENOMEM;
pfile_info = kzalloc(sizeof(struct smb2_file_all_info) + PATH_MAX * 2,
GFP_KERNEL);
if (pfile_info == NULL) {
kfree(utf16_path);
return -ENOMEM;
}
rc = SMB2_open(xid, &oparms, utf16_path, &oplock, pfile_info, NULL,
NULL);
if (rc)
goto qmf_out_open_fail;
if (pfile_info->EndOfFile != cpu_to_le64(CIFS_MF_SYMLINK_FILE_SIZE)) {
/* it's not a symlink */
rc = -ENOENT; /* Is there a better rc to return? */
goto qmf_out;
}
io_parms.netfid = fid.netfid;
io_parms.pid = current->tgid;
io_parms.tcon = tcon;
io_parms.offset = 0;
io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
io_parms.persistent_fid = fid.persistent_fid;
io_parms.volatile_fid = fid.volatile_fid;
rc = SMB2_read(xid, &io_parms, pbytes_read, &pbuf, &buf_type);
qmf_out:
SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);
qmf_out_open_fail:
kfree(utf16_path);
kfree(pfile_info);
return rc;
}
int
smb3_create_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
struct cifs_sb_info *cifs_sb, const unsigned char *path,
char *pbuf, unsigned int *pbytes_written)
{
int rc;
struct cifs_fid fid;
struct cifs_open_parms oparms;
struct cifs_io_parms io_parms;
int create_options = CREATE_NOT_DIR;
__le16 *utf16_path;
__u8 oplock = SMB2_OPLOCK_LEVEL_NONE;
struct kvec iov[2];
if (backup_cred(cifs_sb))
create_options |= CREATE_OPEN_BACKUP_INTENT;
cifs_dbg(FYI, "%s: path: %s\n", __func__, path);
utf16_path = cifs_convert_path_to_utf16(path, cifs_sb);
if (!utf16_path)
return -ENOMEM;
oparms.tcon = tcon;
oparms.cifs_sb = cifs_sb;
oparms.desired_access = GENERIC_WRITE;
oparms.create_options = create_options;
oparms.disposition = FILE_CREATE;
oparms.fid = &fid;
oparms.reconnect = false;
rc = SMB2_open(xid, &oparms, utf16_path, &oplock, NULL, NULL,
NULL);
if (rc) {
kfree(utf16_path);
return rc;
}
io_parms.netfid = fid.netfid;
io_parms.pid = current->tgid;
io_parms.tcon = tcon;
io_parms.offset = 0;
io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
io_parms.persistent_fid = fid.persistent_fid;
io_parms.volatile_fid = fid.volatile_fid;
/* iov[0] is reserved for smb header */
iov[1].iov_base = pbuf;
iov[1].iov_len = CIFS_MF_SYMLINK_FILE_SIZE;
rc = SMB2_write(xid, &io_parms, pbytes_written, iov, 1);
/* Make sure we wrote all of the symlink data */
if ((rc == 0) && (*pbytes_written != CIFS_MF_SYMLINK_FILE_SIZE))
rc = -EIO;
SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);
kfree(utf16_path);
return rc;
}
/*
* M-F Symlink Functions - End
*/
int
cifs_hardlink(struct dentry *old_file, struct inode *inode,
struct dentry *direntry)
{
int rc = -EACCES;
unsigned int xid;
char *from_name = NULL;
char *to_name = NULL;
struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
struct tcon_link *tlink;
struct cifs_tcon *tcon;
struct TCP_Server_Info *server;
struct cifsInodeInfo *cifsInode;
tlink = cifs_sb_tlink(cifs_sb);
if (IS_ERR(tlink))
return PTR_ERR(tlink);
tcon = tlink_tcon(tlink);
xid = get_xid();
from_name = build_path_from_dentry(old_file);
to_name = build_path_from_dentry(direntry);
if ((from_name == NULL) || (to_name == NULL)) {
rc = -ENOMEM;
goto cifs_hl_exit;
}
if (tcon->unix_ext)
rc = CIFSUnixCreateHardLink(xid, tcon, from_name, to_name,
cifs_sb->local_nls,
cifs_remap(cifs_sb));
else {
server = tcon->ses->server;
if (!server->ops->create_hardlink) {
rc = -ENOSYS;
goto cifs_hl_exit;
}
rc = server->ops->create_hardlink(xid, tcon, from_name, to_name,
cifs_sb);
if ((rc == -EIO) || (rc == -EINVAL))
rc = -EOPNOTSUPP;
}
d_drop(direntry); /* force new lookup from server of target */
/*
* if source file is cached (oplocked) revalidate will not go to server
* until the file is closed or oplock broken so update nlinks locally
*/
if (d_really_is_positive(old_file)) {
cifsInode = CIFS_I(d_inode(old_file));
if (rc == 0) {
spin_lock(&d_inode(old_file)->i_lock);
inc_nlink(d_inode(old_file));
spin_unlock(&d_inode(old_file)->i_lock);
/*
* parent dir timestamps will update from srv within a
* second, would it really be worth it to set the parent
* dir cifs inode time to zero to force revalidate
* (faster) for it too?
*/
}
/*
* if not oplocked will force revalidate to get info on source
* file from srv. Note Samba server prior to 4.2 has bug -
* not updating src file ctime on hardlinks but Windows servers
* handle it properly
*/
cifsInode->time = 0;
/*
* Will update parent dir timestamps from srv within a second.
* Would it really be worth it to set the parent dir (cifs
* inode) time field to zero to force revalidate on parent
* directory faster ie
*
* CIFS_I(inode)->time = 0;
*/
}
cifs_hl_exit:
kfree(from_name);
kfree(to_name);
free_xid(xid);
cifs_put_tlink(tlink);
return rc;
}
const char *
cifs_get_link(struct dentry *direntry, struct inode *inode,
struct delayed_call *done)
{
int rc = -ENOMEM;
unsigned int xid;
char *full_path = NULL;
char *target_path = NULL;
struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
struct tcon_link *tlink = NULL;
struct cifs_tcon *tcon;
struct TCP_Server_Info *server;
if (!direntry)
return ERR_PTR(-ECHILD);
xid = get_xid();
tlink = cifs_sb_tlink(cifs_sb);
if (IS_ERR(tlink)) {
free_xid(xid);
return ERR_CAST(tlink);
}
tcon = tlink_tcon(tlink);
server = tcon->ses->server;
full_path = build_path_from_dentry(direntry);
if (!full_path) {
free_xid(xid);
cifs_put_tlink(tlink);
return ERR_PTR(-ENOMEM);
}
cifs_dbg(FYI, "Full path: %s inode = 0x%p\n", full_path, inode);
rc = -EACCES;
/*
* First try Minshall+French Symlinks, if configured
* and fallback to UNIX Extensions Symlinks.
*/
if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
rc = query_mf_symlink(xid, tcon, cifs_sb, full_path,
&target_path);
if (rc != 0 && server->ops->query_symlink) {
struct cifsInodeInfo *cifsi = CIFS_I(inode);
bool reparse_point = false;
if (cifsi->cifsAttrs & ATTR_REPARSE)
reparse_point = true;
rc = server->ops->query_symlink(xid, tcon, cifs_sb, full_path,
&target_path, reparse_point);
}
kfree(full_path);
free_xid(xid);
cifs_put_tlink(tlink);
if (rc != 0) {
kfree(target_path);
return ERR_PTR(rc);
}
set_delayed_call(done, kfree_link, target_path);
return target_path;
}
int
cifs_symlink(struct inode *inode, struct dentry *direntry, const char *symname)
{
int rc = -EOPNOTSUPP;
unsigned int xid;
struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
struct tcon_link *tlink;
struct cifs_tcon *pTcon;
char *full_path = NULL;
struct inode *newinode = NULL;
xid = get_xid();
tlink = cifs_sb_tlink(cifs_sb);
if (IS_ERR(tlink)) {
rc = PTR_ERR(tlink);
goto symlink_exit;
}
pTcon = tlink_tcon(tlink);
full_path = build_path_from_dentry(direntry);
if (full_path == NULL) {
rc = -ENOMEM;
goto symlink_exit;
}
cifs_dbg(FYI, "Full path: %s\n", full_path);
cifs_dbg(FYI, "symname is %s\n", symname);
/* BB what if DFS and this volume is on different share? BB */
if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MF_SYMLINKS)
rc = create_mf_symlink(xid, pTcon, cifs_sb, full_path, symname);
else if (pTcon->unix_ext)
rc = CIFSUnixCreateSymLink(xid, pTcon, full_path, symname,
cifs_sb->local_nls,
cifs_remap(cifs_sb));
/* else
rc = CIFSCreateReparseSymLink(xid, pTcon, fromName, toName,
cifs_sb_target->local_nls); */
if (rc == 0) {
if (pTcon->unix_ext)
rc = cifs_get_inode_info_unix(&newinode, full_path,
inode->i_sb, xid);
else
rc = cifs_get_inode_info(&newinode, full_path, NULL,
inode->i_sb, xid, NULL);
if (rc != 0) {
cifs_dbg(FYI, "Create symlink ok, getinodeinfo fail rc = %d\n",
rc);
} else {
d_instantiate(direntry, newinode);
}
}
symlink_exit:
kfree(full_path);
cifs_put_tlink(tlink);
free_xid(xid);
return rc;
}
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