ksmbd: improve credits management

* Requests except READ, WRITE, IOCTL, INFO, QUERY
DIRECOTRY, CANCEL must consume one credit.
* If client's granted credits are insufficient,
refuse to handle requests.
* Windows server 2016 or later grant up to 8192
credits to clients at once.

Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/ksmbd/connection.c b/fs/ksmbd/connection.c
index 48b18b4ec117e85393ffc72023d359a7ca45c19e..b57a0d8a392ff5c8a388e042be4811edcd0a7d9f 100644 (file)
--- a/fs/ksmbd/connection.c
+++ b/fs/ksmbd/connection.c
@@ -61,6 +61,8 @@ struct ksmbd_conn *ksmbd_conn_alloc(void)
                conn->local_nls = load_nls_default();
        atomic_set(&conn->req_running, 0);
        atomic_set(&conn->r_count, 0);
+       conn->total_credits = 1;
+
        init_waitqueue_head(&conn->req_running_q);
        INIT_LIST_HEAD(&conn->conns_list);
        INIT_LIST_HEAD(&conn->sessions);

diff --git a/fs/ksmbd/smb2misc.c b/fs/ksmbd/smb2misc.c
index 9edd9c161b275e194f45045de6bef2f442e3820f..e7e441c8f050db7be2c91644177ce806e9f0c93f 100644 (file)
--- a/fs/ksmbd/smb2misc.c
+++ b/fs/ksmbd/smb2misc.c
@@ -284,11 +284,13 @@ static inline int smb2_ioctl_resp_len(struct smb2_ioctl_req *h)
                le32_to_cpu(h->MaxOutputResponse);
 }
 
-static int smb2_validate_credit_charge(struct smb2_hdr *hdr)
+static int smb2_validate_credit_charge(struct ksmbd_conn *conn,
+                                      struct smb2_hdr *hdr)
 {
-       int req_len = 0, expect_resp_len = 0, calc_credit_num, max_len;
-       int credit_charge = le16_to_cpu(hdr->CreditCharge);
+       unsigned int req_len = 0, expect_resp_len = 0, calc_credit_num, max_len;
+       unsigned short credit_charge = le16_to_cpu(hdr->CreditCharge);
        void *__hdr = hdr;
+       int ret;
 
        switch (hdr->Command) {
        case SMB2_QUERY_INFO:
@@ -310,21 +312,37 @@ static int smb2_validate_credit_charge(struct smb2_hdr *hdr)
                req_len = smb2_ioctl_req_len(__hdr);
                expect_resp_len = smb2_ioctl_resp_len(__hdr);
                break;
-       default:
+       case SMB2_CANCEL:
                return 0;
+       default:
+               req_len = 1;
+               break;
        }
 
-       credit_charge = max(1, credit_charge);
-       max_len = max(req_len, expect_resp_len);
+       credit_charge = max_t(unsigned short, credit_charge, 1);
+       max_len = max_t(unsigned int, req_len, expect_resp_len);
        calc_credit_num = DIV_ROUND_UP(max_len, SMB2_MAX_BUFFER_SIZE);
 
        if (credit_charge < calc_credit_num) {
-               pr_err("Insufficient credit charge, given: %d, needed: %d\n",
-                      credit_charge, calc_credit_num);
+               ksmbd_debug(SMB, "Insufficient credit charge, given: %d, needed: %d\n",
+                           credit_charge, calc_credit_num);
+               return 1;
+       } else if (credit_charge > conn->max_credits) {
+               ksmbd_debug(SMB, "Too large credit charge: %d\n", credit_charge);
                return 1;
        }
 
-       return 0;
+       spin_lock(&conn->credits_lock);
+       if (credit_charge <= conn->total_credits) {
+               conn->total_credits -= credit_charge;
+               ret = 0;
+       } else {
+               ksmbd_debug(SMB, "Insufficient credits granted, given: %u, granted: %u\n",
+                           credit_charge, conn->total_credits);
+               ret = 1;
+       }
+       spin_unlock(&conn->credits_lock);
+       return ret;
 }
 
 int ksmbd_smb2_check_message(struct ksmbd_work *work)
@@ -383,7 +401,7 @@ int ksmbd_smb2_check_message(struct ksmbd_work *work)
        }
 
        if ((work->conn->vals->capabilities & SMB2_GLOBAL_CAP_LARGE_MTU) &&
-           smb2_validate_credit_charge(hdr)) {
+           smb2_validate_credit_charge(work->conn, hdr)) {
                work->conn->ops->set_rsp_status(work, STATUS_INVALID_PARAMETER);
                return 1;
        }

diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index 1c7b837c81064e101a4a8afeabf11c79ea7653aa..79b296abe04e4e25e332b696a216940d4524df9c 100644 (file)
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -292,22 +292,6 @@ int init_smb2_neg_rsp(struct ksmbd_work *work)
        return 0;
 }
 
-static int smb2_consume_credit_charge(struct ksmbd_work *work,
-                                     unsigned short credit_charge)
-{
-       struct ksmbd_conn *conn = work->conn;
-       unsigned int rsp_credits = 1;
-
-       if (!conn->total_credits)
-               return 0;
-
-       if (credit_charge > 0)
-               rsp_credits = credit_charge;
-
-       conn->total_credits -= rsp_credits;
-       return rsp_credits;
-}
-
 /**
  * smb2_set_rsp_credits() - set number of credits in response buffer
  * @work:      smb work containing smb response buffer
@@ -317,49 +301,43 @@ int smb2_set_rsp_credits(struct ksmbd_work *work)
        struct smb2_hdr *req_hdr = ksmbd_req_buf_next(work);
        struct smb2_hdr *hdr = ksmbd_resp_buf_next(work);
        struct ksmbd_conn *conn = work->conn;
-       unsigned short credits_requested = le16_to_cpu(req_hdr->CreditRequest);
-       unsigned short credit_charge = 1, credits_granted = 0;
-       unsigned short aux_max, aux_credits, min_credits;
-       int rsp_credit_charge;
+       unsigned short credits_requested;
+       unsigned short credit_charge, credits_granted = 0;
+       unsigned short aux_max, aux_credits;
 
-       if (hdr->Command == SMB2_CANCEL)
-               goto out;
+       if (work->send_no_response)
+               return 0;
 
-       /* get default minimum credits by shifting maximum credits by 4 */
-       min_credits = conn->max_credits >> 4;
+       hdr->CreditCharge = req_hdr->CreditCharge;
 
-       if (conn->total_credits >= conn->max_credits) {
+       if (conn->total_credits > conn->max_credits) {
+               hdr->CreditRequest = 0;
                pr_err("Total credits overflow: %d\n", conn->total_credits);
-               conn->total_credits = min_credits;
-       }
-
-       rsp_credit_charge =
-               smb2_consume_credit_charge(work, le16_to_cpu(req_hdr->CreditCharge));
-       if (rsp_credit_charge < 0)
                return -EINVAL;
+       }
 
-       hdr->CreditCharge = cpu_to_le16(rsp_credit_charge);
+       credit_charge = max_t(unsigned short,
+                             le16_to_cpu(req_hdr->CreditCharge), 1);
+       credits_requested = max_t(unsigned short,
+                                 le16_to_cpu(req_hdr->CreditRequest), 1);
 
-       if (credits_requested > 0) {
-               aux_credits = credits_requested - 1;
-               aux_max = 32;
-               if (hdr->Command == SMB2_NEGOTIATE)
-                       aux_max = 0;
-               aux_credits = (aux_credits < aux_max) ? aux_credits : aux_max;
-               credits_granted = aux_credits + credit_charge;
+       /* according to smb2.credits smbtorture, Windows server
+        * 2016 or later grant up to 8192 credits at once.
+        *
+        * TODO: Need to adjuct CreditRequest value according to
+        * current cpu load
+        */
+       aux_credits = credits_requested - 1;
+       if (hdr->Command == SMB2_NEGOTIATE)
+               aux_max = 0;
+       else
+               aux_max = conn->max_credits - credit_charge;
+       aux_credits = min_t(unsigned short, aux_credits, aux_max);
+       credits_granted = credit_charge + aux_credits;
 
-               /* if credits granted per client is getting bigger than default
-                * minimum credits then we should wrap it up within the limits.
-                */
-               if ((conn->total_credits + credits_granted) > min_credits)
-                       credits_granted = min_credits - conn->total_credits;
-               /*
-                * TODO: Need to adjuct CreditRequest value according to
-                * current cpu load
-                */
-       } else if (conn->total_credits == 0) {
-               credits_granted = 1;
-       }
+       if (conn->max_credits - conn->total_credits < credits_granted)
+               credits_granted = conn->max_credits -
+                       conn->total_credits;
 
        conn->total_credits += credits_granted;
        work->credits_granted += credits_granted;
@@ -368,7 +346,6 @@ int smb2_set_rsp_credits(struct ksmbd_work *work)
                /* Update CreditRequest in last request */
                hdr->CreditRequest = cpu_to_le16(work->credits_granted);
        }
-out:
        ksmbd_debug(SMB,
                    "credits: requested[%d] granted[%d] total_granted[%d]\n",
                    credits_requested, credits_granted,