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linux-stable/fs/cifs/smb2misc.c
Sachin Prabhu c11f1df500 cifs: Wait for writebacks to complete before attempting write. 
Problem reported in Red Hat bz 1040329 for strict writes where we cache
only when we hold oplock and write direct to the server when we don't.

When we receive an oplock break, we first change the oplock value for
the inode in cifsInodeInfo->oplock to indicate that we no longer hold
the oplock before we enqueue a task to flush changes to the backing
device. Once we have completed flushing the changes, we return the
oplock to the server.

There are 2 ways here where we can have data corruption
1) While we flush changes to the backing device as part of the oplock
break, we can have processes write to the file. These writes check for
the oplock, find none and attempt to write directly to the server.
These direct writes made while we are flushing from cache could be
overwritten by data being flushed from the cache causing data
corruption.
2) While a thread runs in cifs_strict_writev, the machine could receive
and process an oplock break after the thread has checked the oplock and
found that it allows us to cache and before we have made changes to the
cache. In that case, we end up with a dirty page in cache when we
shouldn't have any. This will be flushed later and will overwrite all
subsequent writes to the part of the file represented by this page.

Before making any writes to the server, we need to confirm that we are
not in the process of flushing data to the server and if we are, we
should wait until the process is complete before we attempt the write.
We should also wait for existing writes to complete before we process
an oplock break request which changes oplock values.

We add a version specific  downgrade_oplock() operation to allow for
differences in the oplock values set for the different smb versions.

Cc: stable@vger.kernel.org
Signed-off-by: Sachin Prabhu <sprabhu@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <smfrench@gmail.com>
2014-04-16 13:51:46 -05:00

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/*
* fs/cifs/smb2misc.c
*
* Copyright (C) International Business Machines Corp., 2002,2011
* Etersoft, 2012
* Author(s): Steve French (sfrench@us.ibm.com)
* Pavel Shilovsky (pshilovsky@samba.org) 2012
*
* 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/ctype.h>
#include "smb2pdu.h"
#include "cifsglob.h"
#include "cifsproto.h"
#include "smb2proto.h"
#include "cifs_debug.h"
#include "cifs_unicode.h"
#include "smb2status.h"
static int
check_smb2_hdr(struct smb2_hdr *hdr, __u64 mid)
{
/*
* Make sure that this really is an SMB, that it is a response,
* and that the message ids match.
*/
if ((*(__le32 *)hdr->ProtocolId == SMB2_PROTO_NUMBER) &&
(mid == hdr->MessageId)) {
if (hdr->Flags & SMB2_FLAGS_SERVER_TO_REDIR)
return 0;
else {
/* only one valid case where server sends us request */
if (hdr->Command == SMB2_OPLOCK_BREAK)
return 0;
else
cifs_dbg(VFS, "Received Request not response\n");
}
} else { /* bad signature or mid */
if (*(__le32 *)hdr->ProtocolId != SMB2_PROTO_NUMBER)
cifs_dbg(VFS, "Bad protocol string signature header %x\n",
*(unsigned int *) hdr->ProtocolId);
if (mid != hdr->MessageId)
cifs_dbg(VFS, "Mids do not match: %llu and %llu\n",
mid, hdr->MessageId);
}
cifs_dbg(VFS, "Bad SMB detected. The Mid=%llu\n", hdr->MessageId);
return 1;
}
/*
* The following table defines the expected "StructureSize" of SMB2 responses
* in order by SMB2 command. This is similar to "wct" in SMB/CIFS responses.
*
* Note that commands are defined in smb2pdu.h in le16 but the array below is
* indexed by command in host byte order
*/
static const __le16 smb2_rsp_struct_sizes[NUMBER_OF_SMB2_COMMANDS] = {
/* SMB2_NEGOTIATE */ __constant_cpu_to_le16(65),
/* SMB2_SESSION_SETUP */ __constant_cpu_to_le16(9),
/* SMB2_LOGOFF */ __constant_cpu_to_le16(4),
/* SMB2_TREE_CONNECT */ __constant_cpu_to_le16(16),
/* SMB2_TREE_DISCONNECT */ __constant_cpu_to_le16(4),
/* SMB2_CREATE */ __constant_cpu_to_le16(89),
/* SMB2_CLOSE */ __constant_cpu_to_le16(60),
/* SMB2_FLUSH */ __constant_cpu_to_le16(4),
/* SMB2_READ */ __constant_cpu_to_le16(17),
/* SMB2_WRITE */ __constant_cpu_to_le16(17),
/* SMB2_LOCK */ __constant_cpu_to_le16(4),
/* SMB2_IOCTL */ __constant_cpu_to_le16(49),
/* BB CHECK this ... not listed in documentation */
/* SMB2_CANCEL */ __constant_cpu_to_le16(0),
/* SMB2_ECHO */ __constant_cpu_to_le16(4),
/* SMB2_QUERY_DIRECTORY */ __constant_cpu_to_le16(9),
/* SMB2_CHANGE_NOTIFY */ __constant_cpu_to_le16(9),
/* SMB2_QUERY_INFO */ __constant_cpu_to_le16(9),
/* SMB2_SET_INFO */ __constant_cpu_to_le16(2),
/* BB FIXME can also be 44 for lease break */
/* SMB2_OPLOCK_BREAK */ __constant_cpu_to_le16(24)
};
int
smb2_check_message(char *buf, unsigned int length)
{
struct smb2_hdr *hdr = (struct smb2_hdr *)buf;
struct smb2_pdu *pdu = (struct smb2_pdu *)hdr;
__u64 mid = hdr->MessageId;
__u32 len = get_rfc1002_length(buf);
__u32 clc_len; /* calculated length */
int command;
/* BB disable following printk later */
cifs_dbg(FYI, "%s length: 0x%x, smb_buf_length: 0x%x\n",
__func__, length, len);
/*
* Add function to do table lookup of StructureSize by command
* ie Validate the wct via smb2_struct_sizes table above
*/
if (length < sizeof(struct smb2_pdu)) {
if ((length >= sizeof(struct smb2_hdr)) && (hdr->Status != 0)) {
pdu->StructureSize2 = 0;
/*
* As with SMB/CIFS, on some error cases servers may
* not return wct properly
*/
return 0;
} else {
cifs_dbg(VFS, "Length less than SMB header size\n");
}
return 1;
}
if (len > CIFSMaxBufSize + MAX_SMB2_HDR_SIZE - 4) {
cifs_dbg(VFS, "SMB length greater than maximum, mid=%llu\n",
mid);
return 1;
}
if (check_smb2_hdr(hdr, mid))
return 1;
if (hdr->StructureSize != SMB2_HEADER_STRUCTURE_SIZE) {
cifs_dbg(VFS, "Illegal structure size %u\n",
le16_to_cpu(hdr->StructureSize));
return 1;
}
command = le16_to_cpu(hdr->Command);
if (command >= NUMBER_OF_SMB2_COMMANDS) {
cifs_dbg(VFS, "Illegal SMB2 command %d\n", command);
return 1;
}
if (smb2_rsp_struct_sizes[command] != pdu->StructureSize2) {
if (command != SMB2_OPLOCK_BREAK_HE && (hdr->Status == 0 ||
pdu->StructureSize2 != SMB2_ERROR_STRUCTURE_SIZE2)) {
/* error packets have 9 byte structure size */
cifs_dbg(VFS, "Illegal response size %u for command %d\n",
le16_to_cpu(pdu->StructureSize2), command);
return 1;
} else if (command == SMB2_OPLOCK_BREAK_HE && (hdr->Status == 0)
&& (le16_to_cpu(pdu->StructureSize2) != 44)
&& (le16_to_cpu(pdu->StructureSize2) != 36)) {
/* special case for SMB2.1 lease break message */
cifs_dbg(VFS, "Illegal response size %d for oplock break\n",
le16_to_cpu(pdu->StructureSize2));
return 1;
}
}
if (4 + len != length) {
cifs_dbg(VFS, "Total length %u RFC1002 length %u mismatch mid %llu\n",
length, 4 + len, mid);
return 1;
}
clc_len = smb2_calc_size(hdr);
if (4 + len != clc_len) {
cifs_dbg(FYI, "Calculated size %u length %u mismatch mid %llu\n",
clc_len, 4 + len, mid);
/* create failed on symlink */
if (command == SMB2_CREATE_HE &&
hdr->Status == STATUS_STOPPED_ON_SYMLINK)
return 0;
/* Windows 7 server returns 24 bytes more */
if (clc_len + 20 == len && command == SMB2_OPLOCK_BREAK_HE)
return 0;
/* server can return one byte more */
if (clc_len == 4 + len + 1)
return 0;
return 1;
}
return 0;
}
/*
* The size of the variable area depends on the offset and length fields
* located in different fields for various SMB2 responses. SMB2 responses
* with no variable length info, show an offset of zero for the offset field.
*/
static const bool has_smb2_data_area[NUMBER_OF_SMB2_COMMANDS] = {
/* SMB2_NEGOTIATE */ true,
/* SMB2_SESSION_SETUP */ true,
/* SMB2_LOGOFF */ false,
/* SMB2_TREE_CONNECT */ false,
/* SMB2_TREE_DISCONNECT */ false,
/* SMB2_CREATE */ true,
/* SMB2_CLOSE */ false,
/* SMB2_FLUSH */ false,
/* SMB2_READ */ true,
/* SMB2_WRITE */ false,
/* SMB2_LOCK */ false,
/* SMB2_IOCTL */ true,
/* SMB2_CANCEL */ false, /* BB CHECK this not listed in documentation */
/* SMB2_ECHO */ false,
/* SMB2_QUERY_DIRECTORY */ true,
/* SMB2_CHANGE_NOTIFY */ true,
/* SMB2_QUERY_INFO */ true,
/* SMB2_SET_INFO */ false,
/* SMB2_OPLOCK_BREAK */ false
};
/*
* Returns the pointer to the beginning of the data area. Length of the data
* area and the offset to it (from the beginning of the smb are also returned.
*/
char *
smb2_get_data_area_len(int *off, int *len, struct smb2_hdr *hdr)
{
*off = 0;
*len = 0;
/* error responses do not have data area */
if (hdr->Status && hdr->Status != STATUS_MORE_PROCESSING_REQUIRED &&
(((struct smb2_err_rsp *)hdr)->StructureSize) ==
SMB2_ERROR_STRUCTURE_SIZE2)
return NULL;
/*
* Following commands have data areas so we have to get the location
* of the data buffer offset and data buffer length for the particular
* command.
*/
switch (hdr->Command) {
case SMB2_NEGOTIATE:
*off = le16_to_cpu(
((struct smb2_negotiate_rsp *)hdr)->SecurityBufferOffset);
*len = le16_to_cpu(
((struct smb2_negotiate_rsp *)hdr)->SecurityBufferLength);
break;
case SMB2_SESSION_SETUP:
*off = le16_to_cpu(
((struct smb2_sess_setup_rsp *)hdr)->SecurityBufferOffset);
*len = le16_to_cpu(
((struct smb2_sess_setup_rsp *)hdr)->SecurityBufferLength);
break;
case SMB2_CREATE:
*off = le32_to_cpu(
((struct smb2_create_rsp *)hdr)->CreateContextsOffset);
*len = le32_to_cpu(
((struct smb2_create_rsp *)hdr)->CreateContextsLength);
break;
case SMB2_QUERY_INFO:
*off = le16_to_cpu(
((struct smb2_query_info_rsp *)hdr)->OutputBufferOffset);
*len = le32_to_cpu(
((struct smb2_query_info_rsp *)hdr)->OutputBufferLength);
break;
case SMB2_READ:
*off = ((struct smb2_read_rsp *)hdr)->DataOffset;
*len = le32_to_cpu(((struct smb2_read_rsp *)hdr)->DataLength);
break;
case SMB2_QUERY_DIRECTORY:
*off = le16_to_cpu(
((struct smb2_query_directory_rsp *)hdr)->OutputBufferOffset);
*len = le32_to_cpu(
((struct smb2_query_directory_rsp *)hdr)->OutputBufferLength);
break;
case SMB2_IOCTL:
*off = le32_to_cpu(
((struct smb2_ioctl_rsp *)hdr)->OutputOffset);
*len = le32_to_cpu(((struct smb2_ioctl_rsp *)hdr)->OutputCount);
break;
case SMB2_CHANGE_NOTIFY:
default:
/* BB FIXME for unimplemented cases above */
cifs_dbg(VFS, "no length check for command\n");
break;
}
/*
* Invalid length or offset probably means data area is invalid, but
* we have little choice but to ignore the data area in this case.
*/
if (*off > 4096) {
cifs_dbg(VFS, "offset %d too large, data area ignored\n", *off);
*len = 0;
*off = 0;
} else if (*off < 0) {
cifs_dbg(VFS, "negative offset %d to data invalid ignore data area\n",
*off);
*off = 0;
*len = 0;
} else if (*len < 0) {
cifs_dbg(VFS, "negative data length %d invalid, data area ignored\n",
*len);
*len = 0;
} else if (*len > 128 * 1024) {
cifs_dbg(VFS, "data area larger than 128K: %d\n", *len);
*len = 0;
}
/* return pointer to beginning of data area, ie offset from SMB start */
if ((*off != 0) && (*len != 0))
return hdr->ProtocolId + *off;
else
return NULL;
}
/*
* Calculate the size of the SMB message based on the fixed header
* portion, the number of word parameters and the data portion of the message.
*/
unsigned int
smb2_calc_size(void *buf)
{
struct smb2_hdr *hdr = (struct smb2_hdr *)buf;
struct smb2_pdu *pdu = (struct smb2_pdu *)hdr;
int offset; /* the offset from the beginning of SMB to data area */
int data_length; /* the length of the variable length data area */
/* Structure Size has already been checked to make sure it is 64 */
int len = 4 + le16_to_cpu(pdu->hdr.StructureSize);
/*
* StructureSize2, ie length of fixed parameter area has already
* been checked to make sure it is the correct length.
*/
len += le16_to_cpu(pdu->StructureSize2);
if (has_smb2_data_area[le16_to_cpu(hdr->Command)] == false)
goto calc_size_exit;
smb2_get_data_area_len(&offset, &data_length, hdr);
cifs_dbg(FYI, "SMB2 data length %d offset %d\n", data_length, offset);
if (data_length > 0) {
/*
* Check to make sure that data area begins after fixed area,
* Note that last byte of the fixed area is part of data area
* for some commands, typically those with odd StructureSize,
* so we must add one to the calculation (and 4 to account for
* the size of the RFC1001 hdr.
*/
if (offset + 4 + 1 < len) {
cifs_dbg(VFS, "data area offset %d overlaps SMB2 header %d\n",
offset + 4 + 1, len);
data_length = 0;
} else {
len = 4 + offset + data_length;
}
}
calc_size_exit:
cifs_dbg(FYI, "SMB2 len %d\n", len);
return len;
}
/* Note: caller must free return buffer */
__le16 *
cifs_convert_path_to_utf16(const char *from, struct cifs_sb_info *cifs_sb)
{
int len;
const char *start_of_path;
__le16 *to;
/* Windows doesn't allow paths beginning with \ */
if (from[0] == '\\')
start_of_path = from + 1;
else
start_of_path = from;
to = cifs_strndup_to_utf16(start_of_path, PATH_MAX, &len,
cifs_sb->local_nls,
cifs_sb->mnt_cifs_flags &
CIFS_MOUNT_MAP_SPECIAL_CHR);
return to;
}
__le32
smb2_get_lease_state(struct cifsInodeInfo *cinode)
{
__le32 lease = 0;
if (CIFS_CACHE_WRITE(cinode))
lease |= SMB2_LEASE_WRITE_CACHING;
if (CIFS_CACHE_HANDLE(cinode))
lease |= SMB2_LEASE_HANDLE_CACHING;
if (CIFS_CACHE_READ(cinode))
lease |= SMB2_LEASE_READ_CACHING;
return lease;
}
struct smb2_lease_break_work {
struct work_struct lease_break;
struct tcon_link *tlink;
__u8 lease_key[16];
__le32 lease_state;
};
static void
cifs_ses_oplock_break(struct work_struct *work)
{
struct smb2_lease_break_work *lw = container_of(work,
struct smb2_lease_break_work, lease_break);
int rc;
rc = SMB2_lease_break(0, tlink_tcon(lw->tlink), lw->lease_key,
lw->lease_state);
cifs_dbg(FYI, "Lease release rc %d\n", rc);
cifs_put_tlink(lw->tlink);
kfree(lw);
}
static bool
smb2_tcon_has_lease(struct cifs_tcon *tcon, struct smb2_lease_break *rsp,
struct smb2_lease_break_work *lw)
{
bool found;
__u8 lease_state;
struct list_head *tmp;
struct cifsFileInfo *cfile;
struct TCP_Server_Info *server = tcon->ses->server;
struct cifs_pending_open *open;
struct cifsInodeInfo *cinode;
int ack_req = le32_to_cpu(rsp->Flags &
SMB2_NOTIFY_BREAK_LEASE_FLAG_ACK_REQUIRED);
lease_state = le32_to_cpu(rsp->NewLeaseState);
list_for_each(tmp, &tcon->openFileList) {
cfile = list_entry(tmp, struct cifsFileInfo, tlist);
cinode = CIFS_I(cfile->dentry->d_inode);
if (memcmp(cinode->lease_key, rsp->LeaseKey,
SMB2_LEASE_KEY_SIZE))
continue;
cifs_dbg(FYI, "found in the open list\n");
cifs_dbg(FYI, "lease key match, lease break 0x%d\n",
le32_to_cpu(rsp->NewLeaseState));
server->ops->set_oplock_level(cinode, lease_state, 0, NULL);
if (ack_req)
cfile->oplock_break_cancelled = false;
else
cfile->oplock_break_cancelled = true;
queue_work(cifsiod_wq, &cfile->oplock_break);
kfree(lw);
return true;
}
found = false;
list_for_each_entry(open, &tcon->pending_opens, olist) {
if (memcmp(open->lease_key, rsp->LeaseKey,
SMB2_LEASE_KEY_SIZE))
continue;
if (!found && ack_req) {
found = true;
memcpy(lw->lease_key, open->lease_key,
SMB2_LEASE_KEY_SIZE);
lw->tlink = cifs_get_tlink(open->tlink);
queue_work(cifsiod_wq, &lw->lease_break);
}
cifs_dbg(FYI, "found in the pending open list\n");
cifs_dbg(FYI, "lease key match, lease break 0x%d\n",
le32_to_cpu(rsp->NewLeaseState));
open->oplock = lease_state;
}
return found;
}
static bool
smb2_is_valid_lease_break(char *buffer)
{
struct smb2_lease_break *rsp = (struct smb2_lease_break *)buffer;
struct list_head *tmp, *tmp1, *tmp2;
struct TCP_Server_Info *server;
struct cifs_ses *ses;
struct cifs_tcon *tcon;
struct smb2_lease_break_work *lw;
lw = kmalloc(sizeof(struct smb2_lease_break_work), GFP_KERNEL);
if (!lw)
return false;
INIT_WORK(&lw->lease_break, cifs_ses_oplock_break);
lw->lease_state = rsp->NewLeaseState;
cifs_dbg(FYI, "Checking for lease break\n");
/* look up tcon based on tid & uid */
spin_lock(&cifs_tcp_ses_lock);
list_for_each(tmp, &cifs_tcp_ses_list) {
server = list_entry(tmp, struct TCP_Server_Info, tcp_ses_list);
list_for_each(tmp1, &server->smb_ses_list) {
ses = list_entry(tmp1, struct cifs_ses, smb_ses_list);
spin_lock(&cifs_file_list_lock);
list_for_each(tmp2, &ses->tcon_list) {
tcon = list_entry(tmp2, struct cifs_tcon,
tcon_list);
cifs_stats_inc(
&tcon->stats.cifs_stats.num_oplock_brks);
if (smb2_tcon_has_lease(tcon, rsp, lw)) {
spin_unlock(&cifs_file_list_lock);
spin_unlock(&cifs_tcp_ses_lock);
return true;
}
}
spin_unlock(&cifs_file_list_lock);
}
}
spin_unlock(&cifs_tcp_ses_lock);
kfree(lw);
cifs_dbg(FYI, "Can not process lease break - no lease matched\n");
return false;
}
bool
smb2_is_valid_oplock_break(char *buffer, struct TCP_Server_Info *server)
{
struct smb2_oplock_break *rsp = (struct smb2_oplock_break *)buffer;
struct list_head *tmp, *tmp1, *tmp2;
struct cifs_ses *ses;
struct cifs_tcon *tcon;
struct cifsInodeInfo *cinode;
struct cifsFileInfo *cfile;
cifs_dbg(FYI, "Checking for oplock break\n");
if (rsp->hdr.Command != SMB2_OPLOCK_BREAK)
return false;
if (rsp->StructureSize !=
smb2_rsp_struct_sizes[SMB2_OPLOCK_BREAK_HE]) {
if (le16_to_cpu(rsp->StructureSize) == 44)
return smb2_is_valid_lease_break(buffer);
else
return false;
}
cifs_dbg(FYI, "oplock level 0x%d\n", rsp->OplockLevel);
/* look up tcon based on tid & uid */
spin_lock(&cifs_tcp_ses_lock);
list_for_each(tmp, &server->smb_ses_list) {
ses = list_entry(tmp, struct cifs_ses, smb_ses_list);
list_for_each(tmp1, &ses->tcon_list) {
tcon = list_entry(tmp1, struct cifs_tcon, tcon_list);
cifs_stats_inc(&tcon->stats.cifs_stats.num_oplock_brks);
spin_lock(&cifs_file_list_lock);
list_for_each(tmp2, &tcon->openFileList) {
cfile = list_entry(tmp2, struct cifsFileInfo,
tlist);
if (rsp->PersistentFid !=
cfile->fid.persistent_fid ||
rsp->VolatileFid !=
cfile->fid.volatile_fid)
continue;
cifs_dbg(FYI, "file id match, oplock break\n");
cinode = CIFS_I(cfile->dentry->d_inode);
if (!CIFS_CACHE_WRITE(cinode) &&
rsp->OplockLevel == SMB2_OPLOCK_LEVEL_NONE)
cfile->oplock_break_cancelled = true;
else
cfile->oplock_break_cancelled = false;
set_bit(CIFS_INODE_PENDING_OPLOCK_BREAK,
&cinode->flags);
/*
* Set flag if the server downgrades the oplock
* to L2 else clear.
*/
if (rsp->OplockLevel)
set_bit(
CIFS_INODE_DOWNGRADE_OPLOCK_TO_L2,
&cinode->flags);
else
clear_bit(
CIFS_INODE_DOWNGRADE_OPLOCK_TO_L2,
&cinode->flags);
queue_work(cifsiod_wq, &cfile->oplock_break);
spin_unlock(&cifs_file_list_lock);
spin_unlock(&cifs_tcp_ses_lock);
return true;
}
spin_unlock(&cifs_file_list_lock);
spin_unlock(&cifs_tcp_ses_lock);
cifs_dbg(FYI, "No matching file for oplock break\n");
return true;
}
}
spin_unlock(&cifs_tcp_ses_lock);
cifs_dbg(FYI, "Can not process oplock break for non-existent connection\n");
return false;
}
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