Merge tag '5.15-rc6-ksmbd-fixes' of git://git.samba.org/ksmbd

Pull ksmbd fixes from Steve French:
 "Ten fixes for the ksmbd kernel server, for improved security and
  additional buffer overflow checks:

   - a security improvement to session establishment to reduce the
     possibility of dictionary attacks

   - fix to ensure that maximum i/o size negotiated in the protocol is
     not less than 64K and not more than 8MB to better match expected
     behavior

   - fix for crediting (flow control) important to properly verify that
     sufficient credits are available for the requested operation

   - seven additional buffer overflow, buffer validation checks"

* tag '5.15-rc6-ksmbd-fixes' of git://git.samba.org/ksmbd:
  ksmbd: add buffer validation in session setup
  ksmbd: throttle session setup failures to avoid dictionary attacks
  ksmbd: validate OutputBufferLength of QUERY_DIR, QUERY_INFO, IOCTL requests
  ksmbd: validate credit charge after validating SMB2 PDU body size
  ksmbd: add buffer validation for smb direct
  ksmbd: limit read/write/trans buffer size not to exceed 8MB
  ksmbd: validate compound response buffer
  ksmbd: fix potencial 32bit overflow from data area check in smb2_write
  ksmbd: improve credits management
  ksmbd: add validation in smb2_ioctl

Author: torvalds

fs/ksmbd/auth.c

@@ -298,8 +298,8 @@ int ksmbd_decode_ntlmssp_auth_blob(struct authenticate_message *authblob,
 				   int blob_len, struct ksmbd_session *sess)
 {
 	char *domain_name;
-	unsigned int lm_off, nt_off;
-	unsigned short nt_len;
+	unsigned int nt_off, dn_off;
+	unsigned short nt_len, dn_len;
 	int ret;
 
 	if (blob_len < sizeof(struct authenticate_message)) {
@@ -314,15 +314,17 @@ int ksmbd_decode_ntlmssp_auth_blob(struct authenticate_message *authblob,
 		return -EINVAL;
 	}
 
-	lm_off = le32_to_cpu(authblob->LmChallengeResponse.BufferOffset);
 	nt_off = le32_to_cpu(authblob->NtChallengeResponse.BufferOffset);
 	nt_len = le16_to_cpu(authblob->NtChallengeResponse.Length);
+	dn_off = le32_to_cpu(authblob->DomainName.BufferOffset);
+	dn_len = le16_to_cpu(authblob->DomainName.Length);
+
+	if (blob_len < (u64)dn_off + dn_len || blob_len < (u64)nt_off + nt_len)
+		return -EINVAL;
 
 	/* TODO : use domain name that imported from configuration file */
-	domain_name = smb_strndup_from_utf16((const char *)authblob +
-			le32_to_cpu(authblob->DomainName.BufferOffset),
-			le16_to_cpu(authblob->DomainName.Length), true,
-			sess->conn->local_nls);
+	domain_name = smb_strndup_from_utf16((const char *)authblob + dn_off,
+					     dn_len, true, sess->conn->local_nls);
 	if (IS_ERR(domain_name))
 		return PTR_ERR(domain_name);
 

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);

fs/ksmbd/ksmbd_netlink.h

@@ -211,6 +211,7 @@ struct ksmbd_tree_disconnect_request {
  */
 struct ksmbd_logout_request {
 	__s8	account[KSMBD_REQ_MAX_ACCOUNT_NAME_SZ]; /* user account name */
+	__u32	account_flags;
 };
 
 /*
@@ -317,6 +318,7 @@ enum KSMBD_TREE_CONN_STATUS {
 #define KSMBD_USER_FLAG_BAD_UID		BIT(2)
 #define KSMBD_USER_FLAG_BAD_USER	BIT(3)
 #define KSMBD_USER_FLAG_GUEST_ACCOUNT	BIT(4)
+#define KSMBD_USER_FLAG_DELAY_SESSION	BIT(5)
 
 /*
  * Share config flags.

fs/ksmbd/mgmt/user_config.c

@@ -55,7 +55,7 @@ struct ksmbd_user *ksmbd_alloc_user(struct ksmbd_login_response *resp)
 
 void ksmbd_free_user(struct ksmbd_user *user)
 {
-	ksmbd_ipc_logout_request(user->name);
+	ksmbd_ipc_logout_request(user->name, user->flags);
 	kfree(user->name);
 	kfree(user->passkey);
 	kfree(user);

fs/ksmbd/mgmt/user_config.h

@@ -18,6 +18,7 @@ struct ksmbd_user {
 
 	size_t			passkey_sz;
 	char			*passkey;
+	unsigned int		failed_login_count;
 };
 
 static inline bool user_guest(struct ksmbd_user *user)

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)
@@ -382,26 +400,20 @@ int ksmbd_smb2_check_message(struct ksmbd_work *work)
 		}
 	}
 
-	if ((work->conn->vals->capabilities & SMB2_GLOBAL_CAP_LARGE_MTU) &&
-	    smb2_validate_credit_charge(hdr)) {
-		work->conn->ops->set_rsp_status(work, STATUS_INVALID_PARAMETER);
-		return 1;
-	}
-
 	if (smb2_calc_size(hdr, &clc_len))
 		return 1;
 
 	if (len != clc_len) {
 		/* client can return one byte more due to implied bcc[0] */
 		if (clc_len == len + 1)
-			return 0;
+			goto validate_credit;
 
 		/*
 		 * Some windows servers (win2016) will pad also the final
 		 * PDU in a compound to 8 bytes.
 		 */
 		if (ALIGN(clc_len, 8) == len)
-			return 0;
+			goto validate_credit;
 
 		/*
 		 * windows client also pad up to 8 bytes when compounding.
@@ -414,7 +426,7 @@ int ksmbd_smb2_check_message(struct ksmbd_work *work)
 				    "cli req padded more than expected. Length %d not %d for cmd:%d mid:%llu\n",
 				    len, clc_len, command,
 				    le64_to_cpu(hdr->MessageId));
-			return 0;
+			goto validate_credit;
 		}
 
 		ksmbd_debug(SMB,
@@ -425,6 +437,13 @@ int ksmbd_smb2_check_message(struct ksmbd_work *work)
 		return 1;
 	}
 
+validate_credit:
+	if ((work->conn->vals->capabilities & SMB2_GLOBAL_CAP_LARGE_MTU) &&
+	    smb2_validate_credit_charge(work->conn, hdr)) {
+		work->conn->ops->set_rsp_status(work, STATUS_INVALID_PARAMETER);
+		return 1;
+	}
+
 	return 0;
 }
 

fs/ksmbd/smb2ops.c

@@ -284,6 +284,7 @@ int init_smb3_11_server(struct ksmbd_conn *conn)
 
 void init_smb2_max_read_size(unsigned int sz)
 {
+	sz = clamp_val(sz, SMB3_MIN_IOSIZE, SMB3_MAX_IOSIZE);
 	smb21_server_values.max_read_size = sz;
 	smb30_server_values.max_read_size = sz;
 	smb302_server_values.max_read_size = sz;
@@ -292,6 +293,7 @@ void init_smb2_max_read_size(unsigned int sz)
 
 void init_smb2_max_write_size(unsigned int sz)
 {
+	sz = clamp_val(sz, SMB3_MIN_IOSIZE, SMB3_MAX_IOSIZE);
 	smb21_server_values.max_write_size = sz;
 	smb30_server_values.max_write_size = sz;
 	smb302_server_values.max_write_size = sz;
@@ -300,6 +302,7 @@ void init_smb2_max_write_size(unsigned int sz)
 
 void init_smb2_max_trans_size(unsigned int sz)
 {
+	sz = clamp_val(sz, SMB3_MIN_IOSIZE, SMB3_MAX_IOSIZE);
 	smb21_server_values.max_trans_size = sz;
 	smb30_server_values.max_trans_size = sz;
 	smb302_server_values.max_trans_size = sz;