Commit 38bd4906 authored by Sachin Prabhu's avatar Sachin Prabhu Committed by Steve French
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Handle mismatched open calls 



A signal can interrupt a SendReceive call which result in incoming
responses to the call being ignored. This is a problem for calls such as
open which results in the successful response being ignored. This
results in an open file resource on the server.

The patch looks into responses which were cancelled after being sent and
in case of successful open closes the open fids.

For this patch, the check is only done in SendReceive2()

RH-bz: 1403319

Signed-off-by: default avatarSachin Prabhu <sprabhu@redhat.com>
Reviewed-by: default avatarPavel Shilovsky <pshilov@microsoft.com>
Cc: Stable <stable@vger.kernel.org>
parent 269c930e

fs/cifs/cifsglob.h

+11 −0
Original line number Diff line number Diff line
@@ -243,6 +243,7 @@ struct smb_version_operations { 
	/* verify the message */

	int (*check_message)(char *, unsigned int, struct TCP_Server_Info *);

	bool (*is_oplock_break)(char *, struct TCP_Server_Info *);

	int (*handle_cancelled_mid)(char *, struct TCP_Server_Info *);

	void (*downgrade_oplock)(struct TCP_Server_Info *,

					struct cifsInodeInfo *, bool);

	/* process transaction2 response */
@@ -1343,6 +1344,7 @@ struct mid_q_entry { 
	void *callback_data;	  /* general purpose pointer for callback */

	void *resp_buf;		/* pointer to received SMB header */

	int mid_state;	/* wish this were enum but can not pass to wait_event */

	unsigned int mid_flags;

	__le16 command;		/* smb command code */

	bool large_buf:1;	/* if valid response, is pointer to large buf */

	bool multiRsp:1;	/* multiple trans2 responses for one request  */
@@ -1350,6 +1352,12 @@ struct mid_q_entry { 
	bool decrypted:1;	/* decrypted entry */

};



struct close_cancelled_open {

	struct cifs_fid         fid;

	struct cifs_tcon        *tcon;

	struct work_struct      work;

};



/*	Make code in transport.c a little cleaner by moving

	update of optional stats into function below */

#ifdef CONFIG_CIFS_STATS2
@@ -1481,6 +1489,9 @@ static inline void free_dfs_info_array(struct dfs_info3_param *param, 
#define   MID_RESPONSE_MALFORMED 0x10

#define   MID_SHUTDOWN		 0x20



/* Flags */

#define   MID_WAIT_CANCELLED	 1 /* Cancelled while waiting for response */



/* Types of response buffer returned from SendReceive2 */

#define   CIFS_NO_BUFFER        0    /* Response buffer not returned */

#define   CIFS_SMALL_BUFFER     1

fs/cifs/cifsproto.h

+2 −1
Original line number Diff line number Diff line
@@ -79,7 +79,8 @@ extern void cifs_delete_mid(struct mid_q_entry *mid); 
extern void cifs_wake_up_task(struct mid_q_entry *mid);

extern int cifs_handle_standard(struct TCP_Server_Info *server,

				struct mid_q_entry *mid);

extern int cifs_discard_remaining_data(struct TCP_Server_Info *server);

extern int cifs_discard_remaining_data(struct TCP_Server_Info *server,

				       char *buf);

extern int cifs_call_async(struct TCP_Server_Info *server,

			struct smb_rqst *rqst,

			mid_receive_t *receive, mid_callback_t *callback,

fs/cifs/cifssmb.c

+7 −4
Original line number Diff line number Diff line
@@ -1400,9 +1400,9 @@ openRetry: 
 * current bigbuf.

 */

int

cifs_discard_remaining_data(struct TCP_Server_Info *server)

cifs_discard_remaining_data(struct TCP_Server_Info *server, char *buf)

{

	unsigned int rfclen = get_rfc1002_length(server->smallbuf);

	unsigned int rfclen = get_rfc1002_length(buf);

	int remaining = rfclen + 4 - server->total_read;



	while (remaining > 0) {
@@ -1426,7 +1426,7 @@ cifs_readv_discard(struct TCP_Server_Info *server, struct mid_q_entry *mid) 
	int length;

	struct cifs_readdata *rdata = mid->callback_data;



	length = cifs_discard_remaining_data(server);

	length = cifs_discard_remaining_data(server, mid->resp_buf);

	dequeue_mid(mid, rdata->result);

	return length;

}
@@ -1459,7 +1459,7 @@ cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid) 


	if (server->ops->is_status_pending &&

	    server->ops->is_status_pending(buf, server, 0)) {

		cifs_discard_remaining_data(server);

		cifs_discard_remaining_data(server, buf);

		return -1;

	}
@@ -1519,6 +1519,9 @@ cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid) 
	cifs_dbg(FYI, "0: iov_base=%p iov_len=%u\n",

		 rdata->iov[0].iov_base, server->total_read);



	mid->resp_buf = server->smallbuf;

	server->smallbuf = NULL;



	/* how much data is in the response? */

	data_len = server->ops->read_data_length(buf);

	if (data_offset + data_len > buflen) {

fs/cifs/connect.c

+11 −2
Original line number Diff line number Diff line
@@ -904,10 +904,19 @@ cifs_demultiplex_thread(void *p) 


		server->lstrp = jiffies;

		if (mid_entry != NULL) {

			if ((mid_entry->mid_flags & MID_WAIT_CANCELLED) &&

			     mid_entry->mid_state == MID_RESPONSE_RECEIVED &&

					server->ops->handle_cancelled_mid)

				server->ops->handle_cancelled_mid(

							mid_entry->resp_buf,

							server);



			if (!mid_entry->multiRsp || mid_entry->multiEnd)

				mid_entry->callback(mid_entry);

		} else if (!server->ops->is_oplock_break ||

			   !server->ops->is_oplock_break(buf, server)) {

		} else if (server->ops->is_oplock_break &&

			   server->ops->is_oplock_break(buf, server)) {

			cifs_dbg(FYI, "Received oplock break\n");

		} else {

			cifs_dbg(VFS, "No task to wake, unknown frame received! NumMids %d\n",

				 atomic_read(&midCount));

			cifs_dump_mem("Received Data is: ", buf,

fs/cifs/smb2misc.c

+46 −0
Original line number Diff line number Diff line
@@ -659,3 +659,49 @@ smb2_is_valid_oplock_break(char *buffer, struct TCP_Server_Info *server) 
	cifs_dbg(FYI, "Can not process oplock break for non-existent connection\n");

	return false;

}



void

smb2_cancelled_close_fid(struct work_struct *work)

{

	struct close_cancelled_open *cancelled = container_of(work,

					struct close_cancelled_open, work);



	cifs_dbg(VFS, "Close unmatched open\n");



	SMB2_close(0, cancelled->tcon, cancelled->fid.persistent_fid,

		   cancelled->fid.volatile_fid);

	cifs_put_tcon(cancelled->tcon);

	kfree(cancelled);

}



int

smb2_handle_cancelled_mid(char *buffer, struct TCP_Server_Info *server)

{

	struct smb2_sync_hdr *sync_hdr = get_sync_hdr(buffer);

	struct smb2_create_rsp *rsp = (struct smb2_create_rsp *)buffer;

	struct cifs_tcon *tcon;

	struct close_cancelled_open *cancelled;



	if (sync_hdr->Command != SMB2_CREATE ||

	    sync_hdr->Status != STATUS_SUCCESS)

		return 0;



	cancelled = kzalloc(sizeof(*cancelled), GFP_KERNEL);

	if (!cancelled)

		return -ENOMEM;



	tcon = smb2_find_smb_tcon(server, sync_hdr->SessionId,

				  sync_hdr->TreeId);

	if (!tcon) {

		kfree(cancelled);

		return -ENOENT;

	}



	cancelled->fid.persistent_fid = rsp->PersistentFileId;

	cancelled->fid.volatile_fid = rsp->VolatileFileId;

	cancelled->tcon = tcon;

	INIT_WORK(&cancelled->work, smb2_cancelled_close_fid);

	queue_work(cifsiod_wq, &cancelled->work);



	return 0;

}

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