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linux/fs/cifs/link.c
Paulo Alcantara 76894f3e2f cifs: improve symlink handling for smb2+ 
When creating inode for symlink, the client used to send below
requests to fill it in:

    * create+query_info+close (STATUS_STOPPED_ON_SYMLINK)
    * create(+reparse_flag)+query_info+close (set file attrs)
    * create+ioctl(get_reparse)+close (query reparse tag)

and then for every access to the symlink dentry, the ->link() method
would send another:

    * create+ioctl(get_reparse)+close (parse symlink)

So, in order to improve:

    (i) Get rid of unnecessary roundtrips and then resolve symlinks as
	follows:

        * create+query_info+close (STATUS_STOPPED_ON_SYMLINK +
	                           parse symlink + get reparse tag)
        * create(+reparse_flag)+query_info+close (set file attrs)

    (ii) Set the resolved symlink target directly in inode->i_link and
         use simple_get_link() for ->link() to simply return it.

Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
2022-10-13 09:36:04 -05:00

644 lines
15 KiB
C
Raw Blame History

// SPDX-License-Identifier: LGPL-2.1
/*
*
* Copyright (C) International Business Machines Corp., 2002,2008
* Author(s): Steve French (sfrench@us.ibm.com)
*
*/
#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"
#include "cifs_ioctl.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 shash_desc *md5 = NULL;
rc = cifs_alloc_hash("md5", &md5);
if (rc)
goto symlink_hash_err;
rc = crypto_shash_init(md5);
if (rc) {
cifs_dbg(VFS, "%s: Could not init md5 shash\n", __func__);
goto symlink_hash_err;
}
rc = crypto_shash_update(md5, 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(md5, md5_hash);
if (rc)
cifs_dbg(VFS, "%s: Could not generate md5 hash\n", __func__);
symlink_hash_err:
cifs_free_hash(&md5);
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;
if (link_len > CIFS_MF_SYMLINK_LINK_MAXLEN)
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;
}
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;
char *symlink = NULL;
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, &symlink);
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;
fattr->cf_symlink_target = symlink;
out:
kfree(buf);
return rc;
}
#ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
/*
* 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 = {0};
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 = cifs_create_options(cifs_sb, 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 = {0};
oparms.tcon = tcon;
oparms.cifs_sb = cifs_sb;
oparms.desired_access = GENERIC_WRITE;
oparms.create_options = cifs_create_options(cifs_sb, CREATE_NOT_DIR);
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;
}
#endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */
/*
* 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 = {0};
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 = cifs_create_options(cifs_sb, CREATE_NOT_DIR);
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, 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 = {0};
__le16 *utf16_path;
__u8 oplock = SMB2_OPLOCK_LEVEL_NONE;
struct kvec iov[2];
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 = cifs_create_options(cifs_sb, CREATE_NOT_DIR);
oparms.disposition = FILE_CREATE;
oparms.fid = &fid;
oparms.reconnect = false;
rc = SMB2_open(xid, &oparms, utf16_path, &oplock, NULL, 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;
const char *from_name, *to_name;
void *page1, *page2;
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;
if (unlikely(cifs_forced_shutdown(cifs_sb)))
return -EIO;
tlink = cifs_sb_tlink(cifs_sb);
if (IS_ERR(tlink))
return PTR_ERR(tlink);
tcon = tlink_tcon(tlink);
xid = get_xid();
page1 = alloc_dentry_path();
page2 = alloc_dentry_path();
from_name = build_path_from_dentry(old_file, page1);
if (IS_ERR(from_name)) {
rc = PTR_ERR(from_name);
goto cifs_hl_exit;
}
to_name = build_path_from_dentry(direntry, page2);
if (IS_ERR(to_name)) {
rc = PTR_ERR(to_name);
goto cifs_hl_exit;
}
#ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
if (tcon->unix_ext)
rc = CIFSUnixCreateHardLink(xid, tcon, from_name, to_name,
cifs_sb->local_nls,
cifs_remap(cifs_sb));
else {
#else
{
#endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */
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:
free_dentry_path(page1);
free_dentry_path(page2);
free_xid(xid);
cifs_put_tlink(tlink);
return rc;
}
int
cifs_symlink(struct user_namespace *mnt_userns, 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;
const char *full_path;
void *page;
struct inode *newinode = NULL;
if (unlikely(cifs_forced_shutdown(cifs_sb)))
return -EIO;
page = alloc_dentry_path();
if (!page)
return -ENOMEM;
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, page);
if (IS_ERR(full_path)) {
rc = PTR_ERR(full_path);
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);
#ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
else if (pTcon->unix_ext)
rc = CIFSUnixCreateSymLink(xid, pTcon, full_path, symname,
cifs_sb->local_nls,
cifs_remap(cifs_sb));
#endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */
/* else
rc = CIFSCreateReparseSymLink(xid, pTcon, fromName, toName,
cifs_sb_target->local_nls); */
if (rc == 0) {
if (pTcon->posix_extensions)
rc = smb311_posix_get_inode_info(&newinode, full_path, inode->i_sb, xid);
else 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:
free_dentry_path(page);
cifs_put_tlink(tlink);
free_xid(xid);
return rc;
}
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