The patch below does not apply to the 4.16-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 136ff1b4b65edf09b6b7173ba94ad53347d3aa83 Mon Sep 17 00:00:00 2001
From: Steve French <smfrench@xxxxxxxxx>
Date: Sun, 8 Apr 2018 16:14:31 -0500
Subject: [PATCH] SMB3: Fix length checking of SMB3.11 negotiate request
The length checking for SMB3.11 negotiate request includes
"negotiate contexts" which caused a buffer validation problem
and a confusing warning message on SMB3.11 mount e.g.:
SMB2 server sent bad RFC1001 len 236 not 170
Fix the length checking for SMB3.11 negotiate to account for
the new negotiate context so that we don't log a warning on
SMB3.11 mount by default but do log warnings if lengths returned
by the server are incorrect.
CC: Stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Steve French <smfrench@xxxxxxxxx>
Reviewed-by: Aurelien Aptel <aaptel@xxxxxxxx>
Reviewed-by: Pavel Shilovsky <pshilov@xxxxxxxxxxxxx>
diff --git a/fs/cifs/smb2misc.c b/fs/cifs/smb2misc.c
index 5406e95f5d92..9df9f0b48160 100644
--- a/fs/cifs/smb2misc.c
+++ b/fs/cifs/smb2misc.c
@@ -93,6 +93,41 @@ static const __le16 smb2_rsp_struct_sizes[NUMBER_OF_SMB2_COMMANDS] = {
/* SMB2_OPLOCK_BREAK */ cpu_to_le16(24)
};
+#ifdef CONFIG_CIFS_SMB311
+static __u32 get_neg_ctxt_len(struct smb2_hdr *hdr, __u32 len, __u32 non_ctxlen)
+{
+ __u16 neg_count;
+ __u32 nc_offset, size_of_pad_before_neg_ctxts;
+ struct smb2_negotiate_rsp *pneg_rsp = (struct smb2_negotiate_rsp *)hdr;
+
+ /* Negotiate contexts are only valid for latest dialect SMB3.11 */
+ neg_count = le16_to_cpu(pneg_rsp->NegotiateContextCount);
+ if ((neg_count == 0) ||
+ (pneg_rsp->DialectRevision != cpu_to_le16(SMB311_PROT_ID)))
+ return 0;
+
+ /* Make sure that negotiate contexts start after gss security blob */
+ nc_offset = le32_to_cpu(pneg_rsp->NegotiateContextOffset);
+ if (nc_offset < non_ctxlen - 4 /* RFC1001 len field */) {
+ printk_once(KERN_WARNING "invalid negotiate context offset\n");
+ return 0;
+ }
+ size_of_pad_before_neg_ctxts = nc_offset - (non_ctxlen - 4);
+
+ /* Verify that at least minimal negotiate contexts fit within frame */
+ if (len < nc_offset + (neg_count * sizeof(struct smb2_neg_context))) {
+ printk_once(KERN_WARNING "negotiate context goes beyond end\n");
+ return 0;
+ }
+
+ cifs_dbg(FYI, "length of negcontexts %d pad %d\n",
+ len - nc_offset, size_of_pad_before_neg_ctxts);
+
+ /* length of negcontexts including pad from end of sec blob to them */
+ return (len - nc_offset) + size_of_pad_before_neg_ctxts;
+}
+#endif /* CIFS_SMB311 */
+
int
smb2_check_message(char *buf, unsigned int length, struct TCP_Server_Info *srvr)
{
@@ -198,6 +233,10 @@ smb2_check_message(char *buf, unsigned int length, struct TCP_Server_Info *srvr)
clc_len = smb2_calc_size(hdr);
+#ifdef CONFIG_CIFS_SMB311
+ if (shdr->Command == SMB2_NEGOTIATE)
+ clc_len += get_neg_ctxt_len(hdr, len, clc_len);
+#endif /* SMB311 */
if (srvr->vals->header_preamble_size + len != clc_len) {
cifs_dbg(FYI, "Calculated size %u length %zu mismatch mid %llu\n",
clc_len, srvr->vals->header_preamble_size + len, mid);
diff --git a/fs/cifs/smb2pdu.h b/fs/cifs/smb2pdu.h
index 253e2c7c952f..0e0a0af89e4d 100644
--- a/fs/cifs/smb2pdu.h
+++ b/fs/cifs/smb2pdu.h
@@ -263,6 +263,13 @@ struct smb2_negotiate_req {
#define SMB2_NT_FIND 0x00100000
#define SMB2_LARGE_FILES 0x00200000
+struct smb2_neg_context {
+ __le16 ContextType;
+ __le16 DataLength;
+ __le32 Reserved;
+ /* Followed by array of data */
+} __packed;
+
#define SMB311_SALT_SIZE 32
/* Hash Algorithm Types */
#define SMB2_PREAUTH_INTEGRITY_SHA512 cpu_to_le16(0x0001)