s3:smb2_server: implement credit granting similar to windows

This makes it much easier to compare traces.

metze
(cherry picked from commit 648b959b13224105addaae483823bc422ed1cc21)

The last 10 patches address bug #9057 - SMB2 credit handling code has bugs.

diff --git a/source3/smbd/globals.h b/source3/smbd/globals.h
index 664370b08e8f757fb9d769768f216a4907054fb3..eefc2c61d82a21daf811beda31aff4c3b5a6f1e3 100644 (file)
--- a/source3/smbd/globals.h
+++ b/source3/smbd/globals.h
@@ -635,6 +635,9 @@ struct smbd_server_connection {
                 * The maximum number of credits we will ever
                 * grant to the client.
                 *
+                * Typically we will only grant 1/16th of
+                * max_credits.
+                *
                 * This is the "server max credits" parameter.
                 */
                uint16_t max_credits;

diff --git a/source3/smbd/smb2_server.c b/source3/smbd/smb2_server.c
index d983527ea2eef25c678c8f451d0bb86acff08891..cef0677ed1dbcf1d3f3c0bca5ae33356cc9c39c6 100644 (file)
--- a/source3/smbd/smb2_server.c
+++ b/source3/smbd/smb2_server.c
@@ -503,11 +503,33 @@ static void smb2_set_operation_credit(struct smbd_server_connection *sconn,
        uint8_t *outhdr = (uint8_t *)out_vector->iov_base;
        uint16_t credits_requested;
        uint32_t out_flags;
+       uint16_t cmd;
+       NTSTATUS out_status;
        uint16_t credits_granted = 0;
        uint64_t credits_possible;
+       uint16_t current_max_credits;
+
+       /*
+        * first we grant only 1/16th of the max range.
+        *
+        * Windows also starts with the 1/16th and then grants
+        * more later. I was only able to trigger higher
+        * values, when using a verify high credit charge.
+        *
+        * TODO: scale up depending one load, free memory
+        *       or other stuff.
+        *       Maybe also on the relationship between number
+        *       of requests and the used sequence number.
+        *       Which means we would grant more credits
+        *       for client which use multi credit requests.
+        */
+       current_max_credits = sconn->smb2.max_credits / 16;
+       current_max_credits = MAX(current_max_credits, 1);
 
+       cmd = SVAL(inhdr, SMB2_HDR_OPCODE);
        credits_requested = SVAL(inhdr, SMB2_HDR_CREDIT);
        out_flags = IVAL(outhdr, SMB2_HDR_FLAGS);
+       out_status = NT_STATUS(IVAL(outhdr, SMB2_HDR_STATUS));
 
        SMB_ASSERT(sconn->smb2.max_credits >= sconn->smb2.credits_granted);
 
@@ -519,26 +541,34 @@ static void smb2_set_operation_credit(struct smbd_server_connection *sconn,
                 */
                credits_granted = 0;
        } else if (credits_requested > 0) {
-               uint16_t modified_credits_requested;
-               uint32_t multiplier;
-
-               /*
-                * Split up max_credits into 1/16ths, and then scale
-                * the requested credits by how many 16ths have been
-                * currently granted. Less than 1/16th == grant all
-                * requested (100%), scale down as more have been
-                * granted. Never ask for less than 1 as the client
-                * asked for at least 1. JRA.
-                */
+               uint16_t additional_max = 0;
+               uint16_t additional_credits = credits_requested - 1;
 
-               multiplier = 16 - (((sconn->smb2.credits_granted * 16) / sconn->smb2.max_credits) % 16);
-
-               modified_credits_requested = (multiplier * credits_requested) / 16;
-               if (modified_credits_requested == 0) {
-                       modified_credits_requested = 1;
+               switch (cmd) {
+               case SMB2_OP_NEGPROT:
+                       break;
+               case SMB2_OP_SESSSETUP:
+                       /*
+                        * Windows 2012 RC1 starts to grant
+                        * additional credits
+                        * with a successful session setup
+                        */
+                       if (NT_STATUS_IS_OK(out_status)) {
+                               additional_max = 32;
+                       }
+                       break;
+               default:
+                       /*
+                        * We match windows and only grant additional credits
+                        * in chunks of 32.
+                        */
+                       additional_max = 32;
+                       break;
                }
 
-               credits_granted = modified_credits_requested;
+               additional_credits = MIN(additional_credits, additional_max);
+
+               credits_granted = 1 + additional_credits;
        } else if (sconn->smb2.credits_granted == 0) {
                /*
                 * Make sure the client has always at least one credit
@@ -566,7 +596,7 @@ static void smb2_set_operation_credit(struct smbd_server_connection *sconn,
                /* remove UINT64_MAX */
                credits_possible -= 1;
        }
-       credits_possible = MIN(credits_possible, sconn->smb2.max_credits);
+       credits_possible = MIN(credits_possible, current_max_credits);
        credits_possible -= sconn->smb2.seqnum_range;
 
        credits_granted = MIN(credits_granted, credits_possible);
@@ -576,11 +606,12 @@ static void smb2_set_operation_credit(struct smbd_server_connection *sconn,
        sconn->smb2.seqnum_range += credits_granted;
 
        DEBUG(10,("smb2_set_operation_credit: requested %u, "
-               "granted %u, current possible %u, "
+               "granted %u, current possible/max %u/%u, "
                "total granted/max/low/range %u/%u/%llu/%u\n",
                (unsigned int)credits_requested,
                (unsigned int)credits_granted,
                (unsigned int)credits_possible,
+               (unsigned int)current_max_credits,
                (unsigned int)sconn->smb2.credits_granted,
                (unsigned int)sconn->smb2.max_credits,
                (unsigned long long)sconn->smb2.seqnum_low,