[CIFS] Ensure that cifs multiplex ids do not collide.
Signed-off-by: Steve French (sfrench@us.ibm.com)
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index d3773e5..e8287f7 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -147,6 +147,7 @@
/* (returned on Negotiate */
int capabilities; /* allow selective disabling of caps by smb sess */
__u16 timeZone;
+ __u16 CurrentMid; /* multiplex id - rotating counter */
char cryptKey[CIFS_CRYPTO_KEY_SIZE];
char workstation_RFC1001_name[16]; /* 16th byte is always zero */
__u32 sequence_number; /* needed for CIFS PDU signature */
diff --git a/fs/cifs/cifspdu.h b/fs/cifs/cifspdu.h
index 3cef57b..49cc668 100644
--- a/fs/cifs/cifspdu.h
+++ b/fs/cifs/cifspdu.h
@@ -1961,18 +1961,17 @@
perhaps add a CreateDevice - to create Pipes and other special .inodes
Also note POSIX open flags
2) Close - to return the last write time to do cache across close more safely
- 3) PosixQFSInfo - to return statfs info
- 4) FindFirst return unique inode number - what about resume key, two forms short (matches readdir) and full (enough info to cache inodes)
- 5) Mkdir - set mode
+ 3) FindFirst return unique inode number - what about resume key, two
+ forms short (matches readdir) and full (enough info to cache inodes)
+ 4) Mkdir - set mode
And under consideration:
- 6) FindClose2 (return nanosecond timestamp ??)
- 7) Use nanosecond timestamps throughout all time fields if
+ 5) FindClose2 (return nanosecond timestamp ??)
+ 6) Use nanosecond timestamps throughout all time fields if
corresponding attribute flag is set
- 8) sendfile - handle based copy
- 9) Direct i/o
- 10) "POSIX ACL" support
- 11) Misc fcntls?
+ 7) sendfile - handle based copy
+ 8) Direct i/o
+ 9) Misc fcntls?
what about fixing 64 bit alignment
@@ -2028,7 +2027,7 @@
*/
-/* xsymlink is a symlink format that can be used
+/* xsymlink is a symlink format (used by MacOS) that can be used
to save symlink info in a regular file when
mounted to operating systems that do not
support the cifs Unix extensions or EAs (for xattr
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index 66eaa6b..b9b13e3 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -61,9 +61,9 @@
extern int cifs_inet_pton(int, char * source, void *dst);
extern int map_smb_to_linux_error(struct smb_hdr *smb);
extern void header_assemble(struct smb_hdr *, char /* command */ ,
- const struct cifsTconInfo *, int /* specifies length
- of fixed section (word count) in two byte units */
- );
+ const struct cifsTconInfo *, int /* length of
+ fixed section (word count) in two byte units */);
+extern __u16 GetNextMid(struct TCP_Server_Info *server);
extern struct oplock_q_entry * AllocOplockQEntry(struct inode *, u16,
struct cifsTconInfo *);
extern void DeleteOplockQEntry(struct oplock_q_entry *);
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 1b07354..930be09 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -330,7 +330,7 @@
(void **) &pSMB, (void **) &pSMBr);
if (rc)
return rc;
-
+ pSMB->hdr.Mid = GetNextMid(server);
pSMB->hdr.Flags2 |= SMBFLG2_UNICODE;
if (extended_security)
pSMB->hdr.Flags2 |= SMBFLG2_EXT_SEC;
@@ -415,15 +415,14 @@
if(server->secMode & SECMODE_SIGN_REQUIRED)
cERROR(1,
("Server requires /proc/fs/cifs/PacketSigningEnabled"));
- server->secMode &= ~(SECMODE_SIGN_ENABLED |
- SECMODE_SIGN_REQUIRED);
+ server->secMode &= ~(SECMODE_SIGN_ENABLED | SECMODE_SIGN_REQUIRED);
} else if(sign_CIFS_PDUs == 1) {
if((server->secMode & SECMODE_SIGN_REQUIRED) == 0)
- server->secMode &= ~(SECMODE_SIGN_ENABLED |
- SECMODE_SIGN_REQUIRED);
+ server->secMode &= ~(SECMODE_SIGN_ENABLED | SECMODE_SIGN_REQUIRED);
}
}
+
cifs_buf_release(pSMB);
return rc;
}
@@ -519,6 +518,8 @@
smb_buffer_response = (struct smb_hdr *)pSMB; /* BB removeme BB */
if(ses->server) {
+ pSMB->hdr.Mid = GetNextMid(ses->server);
+
if(ses->server->secMode &
(SECMODE_SIGN_REQUIRED | SECMODE_SIGN_ENABLED))
pSMB->hdr.Flags2 |= SMBFLG2_SECURITY_SIGNATURE;
@@ -2519,11 +2520,12 @@
rc = SendReceive(xid, tcon->ses, (struct smb_hdr *) pSMB,
(struct smb_hdr *) pSMBr, &bytes_returned, 0);
- if (rc) {/* BB add logic to retry regular search if Unix search
- rejected unexpectedly by server */
+ if (rc) {/* BB add logic to retry regular search if Unix search rejected unexpectedly by server */
/* BB Add code to handle unsupported level rc */
cFYI(1, ("Error in FindFirst = %d", rc));
- cifs_buf_release(pSMB);
+
+ if (pSMB)
+ cifs_buf_release(pSMB);
/* BB eventually could optimize out free and realloc of buf */
/* for this case */
@@ -2857,7 +2859,10 @@
(void **) &pSMBr);
if (rc)
return rc;
-
+
+ /* server pointer checked in called function,
+ but should never be null here anyway */
+ pSMB->hdr.Mid = GetNextMid(ses->server);
pSMB->hdr.Tid = ses->ipc_tid;
pSMB->hdr.Uid = ses->Suid;
if (ses->capabilities & CAP_STATUS32) {
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 36f7859..9e82560 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1857,6 +1857,7 @@
header_assemble(smb_buffer, SMB_COM_SESSION_SETUP_ANDX,
NULL /* no tCon exists yet */ , 13 /* wct */ );
+ smb_buffer->Mid = GetNextMid(ses->server);
pSMB->req_no_secext.AndXCommand = 0xFF;
pSMB->req_no_secext.MaxBufferSize = cpu_to_le16(ses->server->maxBuf);
pSMB->req_no_secext.MaxMpxCount = cpu_to_le16(ses->server->maxReq);
@@ -2132,6 +2133,8 @@
/* send SMBsessionSetup here */
header_assemble(smb_buffer, SMB_COM_SESSION_SETUP_ANDX,
NULL /* no tCon exists yet */ , 12 /* wct */ );
+
+ smb_buffer->Mid = GetNextMid(ses->server);
pSMB->req.hdr.Flags2 |= SMBFLG2_EXT_SEC;
pSMB->req.AndXCommand = 0xFF;
pSMB->req.MaxBufferSize = cpu_to_le16(ses->server->maxBuf);
@@ -2398,6 +2401,8 @@
/* send SMBsessionSetup here */
header_assemble(smb_buffer, SMB_COM_SESSION_SETUP_ANDX,
NULL /* no tCon exists yet */ , 12 /* wct */ );
+
+ smb_buffer->Mid = GetNextMid(ses->server);
pSMB->req.hdr.Flags2 |= SMBFLG2_EXT_SEC;
pSMB->req.hdr.Flags |= (SMBFLG_CASELESS | SMBFLG_CANONICAL_PATH_FORMAT);
@@ -2740,6 +2745,8 @@
/* send SMBsessionSetup here */
header_assemble(smb_buffer, SMB_COM_SESSION_SETUP_ANDX,
NULL /* no tCon exists yet */ , 12 /* wct */ );
+
+ smb_buffer->Mid = GetNextMid(ses->server);
pSMB->req.hdr.Flags |= (SMBFLG_CASELESS | SMBFLG_CANONICAL_PATH_FORMAT);
pSMB->req.hdr.Flags2 |= SMBFLG2_EXT_SEC;
pSMB->req.AndXCommand = 0xFF;
@@ -3111,6 +3118,8 @@
header_assemble(smb_buffer, SMB_COM_TREE_CONNECT_ANDX,
NULL /*no tid */ , 4 /*wct */ );
+
+ smb_buffer->Mid = GetNextMid(ses->server);
smb_buffer->Uid = ses->Suid;
pSMB = (TCONX_REQ *) smb_buffer;
pSMBr = (TCONX_RSP *) smb_buffer_response;
diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index 20ae415..beeff82 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -34,8 +34,6 @@
extern mempool_t *cifs_req_poolp;
extern struct task_struct * oplockThread;
-static __u16 GlobalMid; /* multiplex id - rotating counter */
-
/* The xid serves as a useful identifier for each incoming vfs request,
in a similar way to the mid which is useful to track each sent smb,
and CurrentXid can also provide a running counter (although it
@@ -51,6 +49,8 @@
GlobalTotalActiveXid++;
if (GlobalTotalActiveXid > GlobalMaxActiveXid)
GlobalMaxActiveXid = GlobalTotalActiveXid; /* keep high water mark for number of simultaneous vfs ops in our filesystem */
+ if(GlobalTotalActiveXid > 65000)
+ cFYI(1,("warning: more than 65000 requests active"));
xid = GlobalCurrentXid++;
spin_unlock(&GlobalMid_Lock);
return xid;
@@ -218,6 +218,76 @@
return;
}
+/*
+ Find a free multiplex id (SMB mid). Otherwise there could be
+ mid collisions which might cause problems, demultiplexing the
+ wrong response to this request. Multiplex ids could collide if
+ one of a series requests takes much longer than the others, or
+ if a very large number of long lived requests (byte range
+ locks or FindNotify requests) are pending. No more than
+ 64K-1 requests can be outstanding at one time. If no
+ mids are available, return zero. A future optimization
+ could make the combination of mids and uid the key we use
+ to demultiplex on (rather than mid alone).
+ In addition to the above check, the cifs demultiplex
+ code already used the command code as a secondary
+ check of the frame and if signing is negotiated the
+ response would be discarded if the mid were the same
+ but the signature was wrong. Since the mid is not put in the
+ pending queue until later (when it is about to be dispatched)
+ we do have to limit the number of outstanding requests
+ to somewhat less than 64K-1 although it is hard to imagine
+ so many threads being in the vfs at one time.
+*/
+__u16 GetNextMid(struct TCP_Server_Info *server)
+{
+ __u16 mid = 0;
+ __u16 last_mid;
+ int collision;
+
+ if(server == NULL)
+ return mid;
+
+ spin_lock(&GlobalMid_Lock);
+ last_mid = server->CurrentMid; /* we do not want to loop forever */
+ server->CurrentMid++;
+ /* This nested loop looks more expensive than it is.
+ In practice the list of pending requests is short,
+ fewer than 50, and the mids are likely to be unique
+ on the first pass through the loop unless some request
+ takes longer than the 64 thousand requests before it
+ (and it would also have to have been a request that
+ did not time out) */
+ while(server->CurrentMid != last_mid) {
+ struct list_head *tmp;
+ struct mid_q_entry *mid_entry;
+
+ collision = 0;
+ if(server->CurrentMid == 0)
+ server->CurrentMid++;
+
+ list_for_each(tmp, &server->pending_mid_q) {
+ mid_entry = list_entry(tmp, struct mid_q_entry, qhead);
+
+ if ((mid_entry->mid == server->CurrentMid) &&
+ (mid_entry->midState == MID_REQUEST_SUBMITTED)) {
+ /* This mid is in use, try a different one */
+ collision = 1;
+ break;
+ }
+ }
+ if(collision == 0) {
+ mid = server->CurrentMid;
+ break;
+ }
+ server->CurrentMid++;
+ }
+ spin_unlock(&GlobalMid_Lock);
+ return mid;
+}
+
+/* NB: MID can not be set if treeCon not passed in, in that
+ case it is responsbility of caller to set the mid */
void
header_assemble(struct smb_hdr *buffer, char smb_command /* command */ ,
const struct cifsTconInfo *treeCon, int word_count
@@ -233,7 +303,8 @@
(2 * word_count) + sizeof (struct smb_hdr) -
4 /* RFC 1001 length field does not count */ +
2 /* for bcc field itself */ ;
- /* Note that this is the only network field that has to be converted to big endian and it is done just before we send it */
+ /* Note that this is the only network field that has to be converted
+ to big endian and it is done just before we send it */
buffer->Protocol[0] = 0xFF;
buffer->Protocol[1] = 'S';
@@ -245,8 +316,6 @@
buffer->Pid = cpu_to_le16((__u16)current->tgid);
buffer->PidHigh = cpu_to_le16((__u16)(current->tgid >> 16));
spin_lock(&GlobalMid_Lock);
- GlobalMid++;
- buffer->Mid = GlobalMid;
spin_unlock(&GlobalMid_Lock);
if (treeCon) {
buffer->Tid = treeCon->tid;
@@ -256,8 +325,9 @@
if (treeCon->ses->capabilities & CAP_STATUS32) {
buffer->Flags2 |= SMBFLG2_ERR_STATUS;
}
-
- buffer->Uid = treeCon->ses->Suid; /* always in LE format */
+ /* Uid is not converted */
+ buffer->Uid = treeCon->ses->Suid;
+ buffer->Mid = GetNextMid(treeCon->ses->server);
if(multiuser_mount != 0) {
/* For the multiuser case, there are few obvious technically */
/* possible mechanisms to match the local linux user (uid) */