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SMB3.1.1: update comments clarifying SPNEGO info in negprot response

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Trivial changes to clarify confusing comment about
SPNEGO blog (and also one length comparisons in negotiate
context parsing).

Suggested-by: Tom Talpey <tom@talpey.com>
Suggested-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Steve French 2020-12-09 21:25:13 -06:00
parent f2156d35c9
commit 145024e3e4
1 changed files with 10 additions and 1 deletions
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11
fs/cifs/smb2misc.c
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@ -109,8 +109,17 @@ static __u32 get_neg_ctxt_len(struct smb2_sync_hdr *hdr, __u32 len,
(pneg_rsp->DialectRevision != cpu_to_le16(SMB311_PROT_ID)))
return 0;
/* Make sure that negotiate contexts start after gss security blob */
/*
* if SPNEGO blob present (ie the RFC2478 GSS info which indicates
* which security mechanisms the server supports) make sure that
* the negotiate contexts start after it
*/
nc_offset = le32_to_cpu(pneg_rsp->NegotiateContextOffset);
/*
* non_ctxlen is at least shdr->StructureSize + pdu->StructureSize2
* and the latter is 1 byte bigger than the fix-sized area of the
* NEGOTIATE response
*/
if (nc_offset + 1 < non_ctxlen) {
pr_warn_once("Invalid negotiate context offset %d\n", nc_offset);
return 0;