ksmbd: fix slab-out-of-bounds in init_smb2_rsp_hdr

When smb1 mount fails, KASAN detect slab-out-of-bounds in
init_smb2_rsp_hdr like the following one.
For smb1 negotiate(56bytes) , init_smb2_rsp_hdr() for smb2 is called.
The issue occurs while handling smb1 negotiate as smb2 server operations.
Add smb server operations for smb1 (get_cmd_val, init_rsp_hdr,
allocate_rsp_buf, check_user_session) to handle smb1 negotiate so that
smb2 server operation does not handle it.

[  411.400423] CIFS: VFS: Use of the less secure dialect vers=1.0 is
not recommended unless required for access to very old servers
[  411.400452] CIFS: Attempting to mount \\192.168.45.139\homes
[  411.479312] ksmbd: init_smb2_rsp_hdr : 492
[  411.479323] ==================================================================
[  411.479327] BUG: KASAN: slab-out-of-bounds in
init_smb2_rsp_hdr+0x1e2/0x1f4 [ksmbd]
[  411.479369] Read of size 16 at addr ffff888488ed0734 by task kworker/14:1/199

[  411.479379] CPU: 14 PID: 199 Comm: kworker/14:1 Tainted: G
 OE      6.1.21 #3
[  411.479386] Hardware name: ASUSTeK COMPUTER INC. Z10PA-D8
Series/Z10PA-D8 Series, BIOS 3801 08/23/2019
[  411.479390] Workqueue: ksmbd-io handle_ksmbd_work [ksmbd]
[  411.479425] Call Trace:
[  411.479428]  <TASK>
[  411.479432]  dump_stack_lvl+0x49/0x63
[  411.479444]  print_report+0x171/0x4a8
[  411.479452]  ? kasan_complete_mode_report_info+0x3c/0x200
[  411.479463]  ? init_smb2_rsp_hdr+0x1e2/0x1f4 [ksmbd]
[  411.479497]  kasan_report+0xb4/0x130
[  411.479503]  ? init_smb2_rsp_hdr+0x1e2/0x1f4 [ksmbd]
[  411.479537]  kasan_check_range+0x149/0x1e0
[  411.479543]  memcpy+0x24/0x70
[  411.479550]  init_smb2_rsp_hdr+0x1e2/0x1f4 [ksmbd]
[  411.479585]  handle_ksmbd_work+0x109/0x760 [ksmbd]
[  411.479616]  ? _raw_spin_unlock_irqrestore+0x50/0x50
[  411.479624]  ? smb3_encrypt_resp+0x340/0x340 [ksmbd]
[  411.479656]  process_one_work+0x49c/0x790
[  411.479667]  worker_thread+0x2b1/0x6e0
[  411.479674]  ? process_one_work+0x790/0x790
[  411.479680]  kthread+0x177/0x1b0
[  411.479686]  ? kthread_complete_and_exit+0x30/0x30
[  411.479692]  ret_from_fork+0x22/0x30
[  411.479702]  </TASK>

Fixes: 39b291b86b59 ("ksmbd: return unsupported error on smb1 mount")
Cc: stable@vger.kernel.org
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/ksmbd/server.c b/fs/ksmbd/server.c
index 394b6ceac4312685ebbd57a6087de345b0c4111b..0d8242789dc8fd7a4e39d0ca52bd6e0263275dca 100644 (file)
--- a/fs/ksmbd/server.c
+++ b/fs/ksmbd/server.c
@@ -289,10 +289,7 @@ static int queue_ksmbd_work(struct ksmbd_conn *conn)
        work->request_buf = conn->request_buf;
        conn->request_buf = NULL;
 
-       if (ksmbd_init_smb_server(work)) {
-               ksmbd_free_work_struct(work);
-               return -EINVAL;
-       }
+       ksmbd_init_smb_server(work);
 
        ksmbd_conn_enqueue_request(work);
        atomic_inc(&conn->r_count);

diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index 3656ccac06e3374d8c4482c3c75541068f47eadb..8af939a181be588f932cdca6419a1ac36047a128 100644 (file)
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -229,9 +229,6 @@ int init_smb2_neg_rsp(struct ksmbd_work *work)
        struct smb2_negotiate_rsp *rsp;
        struct ksmbd_conn *conn = work->conn;
 
-       if (conn->need_neg == false)
-               return -EINVAL;
-
        *(__be32 *)work->response_buf =
                cpu_to_be32(conn->vals->header_size);
 

diff --git a/fs/ksmbd/smb_common.c b/fs/ksmbd/smb_common.c
index 9c1ce6d199ce4a46ca9129f69d4715496779450c..af0c2a9b85290de8201640dc2f45896453443fe5 100644 (file)
--- a/fs/ksmbd/smb_common.c
+++ b/fs/ksmbd/smb_common.c
@@ -283,20 +283,121 @@ err_out:
        return BAD_PROT_ID;
 }
 
-int ksmbd_init_smb_server(struct ksmbd_work *work)
+#define SMB_COM_NEGOTIATE_EX   0x0
+
+/**
+ * get_smb1_cmd_val() - get smb command value from smb header
+ * @work:      smb work containing smb header
+ *
+ * Return:      smb command value
+ */
+static u16 get_smb1_cmd_val(struct ksmbd_work *work)
 {
-       struct ksmbd_conn *conn = work->conn;
+       return SMB_COM_NEGOTIATE_EX;
+}
 
-       if (conn->need_neg == false)
+/**
+ * init_smb1_rsp_hdr() - initialize smb negotiate response header
+ * @work:      smb work containing smb request
+ *
+ * Return:      0 on success, otherwise -EINVAL
+ */
+static int init_smb1_rsp_hdr(struct ksmbd_work *work)
+{
+       struct smb_hdr *rsp_hdr = (struct smb_hdr *)work->response_buf;
+       struct smb_hdr *rcv_hdr = (struct smb_hdr *)work->request_buf;
+
+       /*
+        * Remove 4 byte direct TCP header.
+        */
+       *(__be32 *)work->response_buf =
+               cpu_to_be32(sizeof(struct smb_hdr) - 4);
+
+       rsp_hdr->Command = SMB_COM_NEGOTIATE;
+       *(__le32 *)rsp_hdr->Protocol = SMB1_PROTO_NUMBER;
+       rsp_hdr->Flags = SMBFLG_RESPONSE;
+       rsp_hdr->Flags2 = SMBFLG2_UNICODE | SMBFLG2_ERR_STATUS |
+               SMBFLG2_EXT_SEC | SMBFLG2_IS_LONG_NAME;
+       rsp_hdr->Pid = rcv_hdr->Pid;
+       rsp_hdr->Mid = rcv_hdr->Mid;
+       return 0;
+}
+
+/**
+ * smb1_check_user_session() - check for valid session for a user
+ * @work:      smb work containing smb request buffer
+ *
+ * Return:      0 on success, otherwise error
+ */
+static int smb1_check_user_session(struct ksmbd_work *work)
+{
+       unsigned int cmd = work->conn->ops->get_cmd_val(work);
+
+       if (cmd == SMB_COM_NEGOTIATE_EX)
                return 0;
 
-       init_smb3_11_server(conn);
+       return -EINVAL;
+}
+
+/**
+ * smb1_allocate_rsp_buf() - allocate response buffer for a command
+ * @work:      smb work containing smb request
+ *
+ * Return:      0 on success, otherwise -ENOMEM
+ */
+static int smb1_allocate_rsp_buf(struct ksmbd_work *work)
+{
+       work->response_buf = kmalloc(MAX_CIFS_SMALL_BUFFER_SIZE,
+                       GFP_KERNEL | __GFP_ZERO);
+       work->response_sz = MAX_CIFS_SMALL_BUFFER_SIZE;
+
+       if (!work->response_buf) {
+               pr_err("Failed to allocate %u bytes buffer\n",
+                               MAX_CIFS_SMALL_BUFFER_SIZE);
+               return -ENOMEM;
+       }
 
-       if (conn->ops->get_cmd_val(work) != SMB_COM_NEGOTIATE)
-               conn->need_neg = false;
        return 0;
 }
 
+static struct smb_version_ops smb1_server_ops = {
+       .get_cmd_val = get_smb1_cmd_val,
+       .init_rsp_hdr = init_smb1_rsp_hdr,
+       .allocate_rsp_buf = smb1_allocate_rsp_buf,
+       .check_user_session = smb1_check_user_session,
+};
+
+static int smb1_negotiate(struct ksmbd_work *work)
+{
+       return ksmbd_smb_negotiate_common(work, SMB_COM_NEGOTIATE);
+}
+
+static struct smb_version_cmds smb1_server_cmds[1] = {
+       [SMB_COM_NEGOTIATE_EX]  = { .proc = smb1_negotiate, },
+};
+
+static void init_smb1_server(struct ksmbd_conn *conn)
+{
+       conn->ops = &smb1_server_ops;
+       conn->cmds = smb1_server_cmds;
+       conn->max_cmds = ARRAY_SIZE(smb1_server_cmds);
+}
+
+void ksmbd_init_smb_server(struct ksmbd_work *work)
+{
+       struct ksmbd_conn *conn = work->conn;
+       __le32 proto;
+
+       if (conn->need_neg == false)
+               return;
+
+       proto = *(__le32 *)((struct smb_hdr *)work->request_buf)->Protocol;
+       if (proto == SMB1_PROTO_NUMBER)
+               init_smb1_server(conn);
+       else
+               init_smb3_11_server(conn);
+}
+
 int ksmbd_populate_dot_dotdot_entries(struct ksmbd_work *work, int info_level,
                                      struct ksmbd_file *dir,
                                      struct ksmbd_dir_info *d_info,
@@ -444,20 +545,10 @@ static int smb_handle_negotiate(struct ksmbd_work *work)
 
        ksmbd_debug(SMB, "Unsupported SMB1 protocol\n");
 
-       /*
-        * Remove 4 byte direct TCP header, add 2 byte bcc and
-        * 2 byte DialectIndex.
-        */
-       *(__be32 *)work->response_buf =
-               cpu_to_be32(sizeof(struct smb_hdr) - 4 + 2 + 2);
+       /* Add 2 byte bcc and 2 byte DialectIndex. */
+       inc_rfc1001_len(work->response_buf, 4);
        neg_rsp->hdr.Status.CifsError = STATUS_SUCCESS;
 
-       neg_rsp->hdr.Command = SMB_COM_NEGOTIATE;
-       *(__le32 *)neg_rsp->hdr.Protocol = SMB1_PROTO_NUMBER;
-       neg_rsp->hdr.Flags = SMBFLG_RESPONSE;
-       neg_rsp->hdr.Flags2 = SMBFLG2_UNICODE | SMBFLG2_ERR_STATUS |
-               SMBFLG2_EXT_SEC | SMBFLG2_IS_LONG_NAME;
-
        neg_rsp->hdr.WordCount = 1;
        neg_rsp->DialectIndex = cpu_to_le16(work->conn->dialect);
        neg_rsp->ByteCount = 0;
@@ -473,24 +564,13 @@ int ksmbd_smb_negotiate_common(struct ksmbd_work *work, unsigned int command)
                ksmbd_negotiate_smb_dialect(work->request_buf);
        ksmbd_debug(SMB, "conn->dialect 0x%x\n", conn->dialect);
 
-       if (command == SMB2_NEGOTIATE_HE) {
-               struct smb2_hdr *smb2_hdr = smb2_get_msg(work->request_buf);
-
-               if (smb2_hdr->ProtocolId != SMB2_PROTO_NUMBER) {
-                       ksmbd_debug(SMB, "Downgrade to SMB1 negotiation\n");
-                       command = SMB_COM_NEGOTIATE;
-               }
-       }
-
        if (command == SMB2_NEGOTIATE_HE) {
                ret = smb2_handle_negotiate(work);
-               init_smb2_neg_rsp(work);
                return ret;
        }
 
        if (command == SMB_COM_NEGOTIATE) {
                if (__smb2_negotiate(conn)) {
-                       conn->need_neg = true;
                        init_smb3_11_server(conn);
                        init_smb2_neg_rsp(work);
                        ksmbd_debug(SMB, "Upgrade to SMB2 negotiation\n");

diff --git a/fs/ksmbd/smb_common.h b/fs/ksmbd/smb_common.h
index d30ce4c1a151703d9f4f512882ee5995a8f93773..9130d2e3cd78c0966d266f7bf72dfe390bd06462 100644 (file)
--- a/fs/ksmbd/smb_common.h
+++ b/fs/ksmbd/smb_common.h
@@ -427,7 +427,7 @@ bool ksmbd_smb_request(struct ksmbd_conn *conn);
 
 int ksmbd_lookup_dialect_by_id(__le16 *cli_dialects, __le16 dialects_count);
 
-int ksmbd_init_smb_server(struct ksmbd_work *work);
+void ksmbd_init_smb_server(struct ksmbd_work *work);
 
 struct ksmbd_kstat;
 int ksmbd_populate_dot_dotdot_entries(struct ksmbd_work *work,