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ksmbd: improve credits management
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* 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 <[email protected]>
Signed-off-by: Hyunchul Lee <[email protected]>
Signed-off-by: Steve French <[email protected]>
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@hclee
hclee authored and Steve French committed Oct 14, 2021
1 parent f7db8fd commit bf8acc9
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Showing 3 changed files with 59 additions and 62 deletions.
2 changes: 2 additions & 0 deletions fs/ksmbd/connection.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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);
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38 changes: 28 additions & 10 deletions fs/ksmbd/smb2misc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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:
Expand All @@ -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)
Expand Down Expand Up @@ -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;
}
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81 changes: 29 additions & 52 deletions fs/ksmbd/smb2pdu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -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;
Expand All @@ -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,
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