Nice catch.
Merged into cifs-2.6.git for next
> On Sep 17, 2015, at 2:40 PM, Peter Seiderer <ps.rep...@gmx.net> wrote:
>
> Linux cifs mount with ntlmssp against an Mac OS X (Yosemite
> 10.10.5) share fails in case the clocks differ more than +/-2h:
>
> digest-service: digest-request: od failed with 2 proto=ntlmv2
> digest-service: digest-request: kdc failed with -1561745592 proto=ntlmv2
>
> Fix this by (re-)using the given server timestamp for the
> ntlmv2 authentication (as Windows 7 does).
>
> Signed-off-by: Peter Seiderer <ps.rep...@gmx.net>
> ---
> fs/cifs/cifsencrypt.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 51 insertions(+), 2 deletions(-)
>
> diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
> index aa0dc25..e6bfa92 100644
> --- a/fs/cifs/cifsencrypt.c
> +++ b/fs/cifs/cifsencrypt.c
> @@ -444,6 +444,48 @@ find_domain_name(struct cifs_ses *ses, const struct
> nls_table *nls_cp)
> return 0;
> }
>
> +/* Server has provided av pairs/target info in the type 2 challenge
> + * packet and we have plucked it and stored within smb session.
> + * We parse that blob here to find the server given timestamp
> + * as part of ntlmv2 authentication (or local current time as
> + * default in case of failure)
> + */
> +static u64
> +find_timestamp(struct cifs_ses *ses)
> +{
> + unsigned int attrsize;
> + unsigned int type;
> + unsigned int onesize = sizeof(struct ntlmssp2_name);
> + unsigned char *blobptr;
> + unsigned char *blobend;
> + struct ntlmssp2_name *attrptr;
> +
> + if (!ses->auth_key.len || !ses->auth_key.response)
> + return 0;
> +
> + blobptr = ses->auth_key.response;
> + blobend = blobptr + ses->auth_key.len;
> +
> + while (blobptr + onesize < blobend) {
> + attrptr = (struct ntlmssp2_name *) blobptr;
> + type = le16_to_cpu(attrptr->type);
> + if (type == NTLMSSP_AV_EOL)
> + break;
> + blobptr += 2; /* advance attr type */
> + attrsize = le16_to_cpu(attrptr->length);
> + blobptr += 2; /* advance attr size */
> + if (blobptr + attrsize > blobend)
> + break;
> + if (type == NTLMSSP_AV_TIMESTAMP) {
> + if (attrsize == sizeof(u64))
> + return *((u64 *)blobptr);
> + }
> + blobptr += attrsize; /* advance attr value */
> + }
> +
> + return cpu_to_le64(cifs_UnixTimeToNT(CURRENT_TIME));
> +}
> +
> static int calc_ntlmv2_hash(struct cifs_ses *ses, char *ntlmv2_hash,
> const struct nls_table *nls_cp)
> {
> @@ -641,6 +683,7 @@ setup_ntlmv2_rsp(struct cifs_ses *ses, const struct
> nls_table *nls_cp)
> struct ntlmv2_resp *ntlmv2;
> char ntlmv2_hash[16];
> unsigned char *tiblob = NULL; /* target info blob */
> + u64 rsp_timestamp;
>
> if (ses->server->negflavor == CIFS_NEGFLAVOR_EXTENDED) {
> if (!ses->domainName) {
> @@ -659,6 +702,12 @@ setup_ntlmv2_rsp(struct cifs_ses *ses, const struct
> nls_table *nls_cp)
> }
> }
>
> + /* Must be within 5 minutes of the server (or in range +/-2h
> + * in case of Mac OS X), so simply carry over server timestamp
> + * (as Windows 7 does)
> + */
> + rsp_timestamp = find_timestamp(ses);
> +
> baselen = CIFS_SESS_KEY_SIZE + sizeof(struct ntlmv2_resp);
> tilen = ses->auth_key.len;
> tiblob = ses->auth_key.response;
> @@ -675,8 +724,8 @@ setup_ntlmv2_rsp(struct cifs_ses *ses, const struct
> nls_table *nls_cp)
> (ses->auth_key.response + CIFS_SESS_KEY_SIZE);
> ntlmv2->blob_signature = cpu_to_le32(0x00000101);
> ntlmv2->reserved = 0;
> - /* Must be within 5 minutes of the server */
> - ntlmv2->time = cpu_to_le64(cifs_UnixTimeToNT(CURRENT_TIME));
> + ntlmv2->time = rsp_timestamp;
> +
> get_random_bytes(&ntlmv2->client_chal, sizeof(ntlmv2->client_chal));
> ntlmv2->reserved2 = 0;
>
> --
> 2.1.4
>
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