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-rw-r--r--fs/cifs/sess.c87
1 files changed, 85 insertions, 2 deletions
diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c
index b234407a300..5c68b4282be 100644
--- a/fs/cifs/sess.c
+++ b/fs/cifs/sess.c
@@ -34,15 +34,99 @@
extern void SMBNTencrypt(unsigned char *passwd, unsigned char *c8,
unsigned char *p24);
+/* Checks if this is the first smb session to be reconnected after
+ the socket has been reestablished (so we know whether to use vc 0).
+ Called while holding the cifs_tcp_ses_lock, so do not block */
+static bool is_first_ses_reconnect(struct cifsSesInfo *ses)
+{
+ struct list_head *tmp;
+ struct cifsSesInfo *tmp_ses;
+
+ list_for_each(tmp, &ses->server->smb_ses_list) {
+ tmp_ses = list_entry(tmp, struct cifsSesInfo,
+ smb_ses_list);
+ if (tmp_ses->need_reconnect == false)
+ return false;
+ }
+ /* could not find a session that was already connected,
+ this must be the first one we are reconnecting */
+ return true;
+}
+
+/*
+ * vc number 0 is treated specially by some servers, and should be the
+ * first one we request. After that we can use vcnumbers up to maxvcs,
+ * one for each smb session (some Windows versions set maxvcs incorrectly
+ * so maxvc=1 can be ignored). If we have too many vcs, we can reuse
+ * any vc but zero (some servers reset the connection on vcnum zero)
+ *
+ */
+static __le16 get_next_vcnum(struct cifsSesInfo *ses)
+{
+ __u16 vcnum = 0;
+ struct list_head *tmp;
+ struct cifsSesInfo *tmp_ses;
+ __u16 max_vcs = ses->server->max_vcs;
+ __u16 i;
+ int free_vc_found = 0;
+
+ /* Quoting the MS-SMB specification: "Windows-based SMB servers set this
+ field to one but do not enforce this limit, which allows an SMB client
+ to establish more virtual circuits than allowed by this value ... but
+ other server implementations can enforce this limit." */
+ if (max_vcs < 2)
+ max_vcs = 0xFFFF;
+
+ write_lock(&cifs_tcp_ses_lock);
+ if ((ses->need_reconnect) && is_first_ses_reconnect(ses))
+ goto get_vc_num_exit; /* vcnum will be zero */
+ for (i = ses->server->srv_count - 1; i < max_vcs; i++) {
+ if (i == 0) /* this is the only connection, use vc 0 */
+ break;
+
+ free_vc_found = 1;
+
+ list_for_each(tmp, &ses->server->smb_ses_list) {
+ tmp_ses = list_entry(tmp, struct cifsSesInfo,
+ smb_ses_list);
+ if (tmp_ses->vcnum == i) {
+ free_vc_found = 0;
+ break; /* found duplicate, try next vcnum */
+ }
+ }
+ if (free_vc_found)
+ break; /* we found a vcnumber that will work - use it */
+ }
+
+ if (i == 0)
+ vcnum = 0; /* for most common case, ie if one smb session, use
+ vc zero. Also for case when no free vcnum, zero
+ is safest to send (some clients only send zero) */
+ else if (free_vc_found == 0)
+ vcnum = 1; /* we can not reuse vc=0 safely, since some servers
+ reset all uids on that, but 1 is ok. */
+ else
+ vcnum = i;
+ ses->vcnum = vcnum;
+get_vc_num_exit:
+ write_unlock(&cifs_tcp_ses_lock);
+
+ return le16_to_cpu(vcnum);
+}
+
static __u32 cifs_ssetup_hdr(struct cifsSesInfo *ses, SESSION_SETUP_ANDX *pSMB)
{
__u32 capabilities = 0;
/* init fields common to all four types of SessSetup */
- /* note that header is initialized to zero in header_assemble */
+ /* Note that offsets for first seven fields in req struct are same */
+ /* in CIFS Specs so does not matter which of 3 forms of struct */
+ /* that we use in next few lines */
+ /* Note that header is initialized to zero in header_assemble */
pSMB->req.AndXCommand = 0xFF;
pSMB->req.MaxBufferSize = cpu_to_le16(ses->server->maxBuf);
pSMB->req.MaxMpxCount = cpu_to_le16(ses->server->maxReq);
+ pSMB->req.VcNumber = get_next_vcnum(ses);
/* Now no need to set SMBFLG_CASELESS or obsolete CANONICAL PATH */
@@ -71,7 +155,6 @@ static __u32 cifs_ssetup_hdr(struct cifsSesInfo *ses, SESSION_SETUP_ANDX *pSMB)
if (ses->capabilities & CAP_UNIX)
capabilities |= CAP_UNIX;
- /* BB check whether to init vcnum BB */
return capabilities;
}