On Tue, 7 Sep 2010 23:46:25 -0500
shirishpargaonkar@xxxxxxxxx wrote:
> From: Shirish Pargaonkar <shirishpargaonkar@xxxxxxxxx>
>
>
> Attribue Value (AV) pairs or Target Info (TI) pairs are part of
> ntlmv2 authentication.
> Structure ntlmv2_resp had only definition for two av pairs.
> So removed it, and now allocation of av pairs is dynamic.
> For servers like Windows 7/2008, av pairs sent by server in
> challege packet (type 2 in the ntlmssp exchange/negotiation) can
> vary.
>
> Server sends them during ntlmssp negotiation. So when ntlmssp is used
> as an authentication mechanism, type 2 challenge packet from server
> has this information. Pluck it and use the entire blob for
> authenticaiton purpose. If user has not specified, extract
> (netbios) domain name from the av pairs which is used to calculate
> ntlmv2 hash. Servers like Windows 7 are particular about the AV pair
> blob.
>
> Servers like Windows 2003, are not very strict about the contents
> of av pair blob used during ntlmv2 authentication.
> So when security mechanism such as ntlmv2 is used (not ntlmv2 in ntlmssp),
> there is no negotiation and so genereate a minimal blob that gets
> used in ntlmv2 authentication as well as gets sent.
>
>
> Signed-off-by: Shirish Pargaonkar <shirishpargaonkar@xxxxxxxxx>
> ---
> fs/cifs/cifsencrypt.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++--
> fs/cifs/cifspdu.h | 1 -
> fs/cifs/connect.c | 2 +
> fs/cifs/sess.c | 18 +++++++++++
> 4 files changed, 93 insertions(+), 5 deletions(-)
>
> diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
> index 4772c4d..e53fbeb 100644
> --- a/fs/cifs/cifsencrypt.c
> +++ b/fs/cifs/cifsencrypt.c
> @@ -27,6 +27,7 @@
> #include "md5.h"
> #include "cifs_unicode.h"
> #include "cifsproto.h"
> +#include "ntlmssp.h"
> #include <linux/ctype.h>
> #include <linux/random.h>
>
> @@ -263,6 +264,78 @@ void calc_lanman_hash(const char *password, const char *cryptkey, bool encrypt,
> }
> #endif /* CIFS_WEAK_PW_HASH */
>
> +/* This is just a filler for ntlmv2 type of security mechanisms.
> + * Older servers are not very particular about the contents of av pairs
> + * in the blob and for sec mechs like ntlmv2, there is no negotiation
> + * as in ntlmssp, so unless domain and server netbios and dns names
> + * are specified, there is no way to obtain name. In case of ntlmssp,
> + * server provides that info in type 2 challenge packet
> + */
> +
^^^ nit: this blank line shouldn't be there
> +static int
> +build_avpair_blob(struct cifsSesInfo *ses)
> +{
> + struct ntlmssp2_name *attrptr;
> +
> + ses->tilen = 2 * sizeof(struct ntlmssp2_name);
^^^
Why 2 here? This deserves a comment.
> + ses->tiblob = kzalloc(ses->tilen, GFP_KERNEL);
> + if (!ses->tiblob) {
> + ses->tilen = 0;
> + cERROR(1, "Challenge target info allocation failure");
> + return -ENOMEM;
> + }
> + attrptr = (struct ntlmssp2_name *) ses->tiblob;
> + attrptr->type = cpu_to_le16(NTLMSSP_DOMAIN_TYPE);
> +
> + return 0;
> +}
> +
> +/* Server has provided av pairs/target info in the type 2 challenge
> + * packet and we have plucked it and stored within smb connection.
> + * We parse that blob here to find netbios domain name to be used
> + * as part of ntlmv2 authentication, if not already specified on
> + * the command line
> + */
> +
^^^^
nit: again, blank line not needed there
> +static int
> +find_domain_name(struct cifsSesInfo *ses)
> +{
> + int rc = 0;
> + unsigned int attrsize;
> + unsigned int type;
> + unsigned char *blobptr;
> + struct ntlmssp2_name *attrptr;
> +
> + if (ses->tiblob) {
> + blobptr = ses->tiblob;
> + attrptr = (struct ntlmssp2_name *) blobptr;
> +
> + while ((type = attrptr->type) != 0) {
> + blobptr += 2; /* advance attr type */
> + attrsize = attrptr->length;
> + blobptr += 2; /* advance attr size */
> + if (type == NTLMSSP_AV_NB_DOMAIN_NAME) {
> + if (!ses->domainName) {
> + ses->domainName =
> + kmalloc(attrptr->length + 1,
> + GFP_KERNEL);
> + if (!ses->domainName)
> + return -ENOMEM;
> + cifs_from_ucs2(ses->domainName,
> + (__le16 *)blobptr,
> + attrptr->length,
> + attrptr->length,
> + load_nls_default(), false);
> + }
> + }
> + blobptr += attrsize; /* advance attr value */
> + attrptr = (struct ntlmssp2_name *) blobptr;
> + }
> + }
> +
> + return rc;
> +}
> +
I think the above function needs some bounds checking. What prevents
the client from trying to access data past the end of the tiblob? I see
no reference to the tilen in that function.
> static int calc_ntlmv2_hash(struct cifsSesInfo *ses,
> const struct nls_table *nls_cp)
> {
> @@ -334,10 +407,6 @@ void setup_ntlmv2_rsp(struct cifsSesInfo *ses, char *resp_buf,
> buf->time = cpu_to_le64(cifs_UnixTimeToNT(CURRENT_TIME));
> get_random_bytes(&buf->client_chal, sizeof(buf->client_chal));
> buf->reserved2 = 0;
> - buf->names[0].type = cpu_to_le16(NTLMSSP_DOMAIN_TYPE);
> - buf->names[0].length = 0;
> - buf->names[1].type = 0;
> - buf->names[1].length = 0;
>
> /* calculate buf->ntlmv2_hash */
> rc = calc_ntlmv2_hash(ses, nls_cp);
> diff --git a/fs/cifs/cifspdu.h b/fs/cifs/cifspdu.h
> index f5c78fb..dc90a36 100644
> --- a/fs/cifs/cifspdu.h
> +++ b/fs/cifs/cifspdu.h
> @@ -670,7 +670,6 @@ struct ntlmv2_resp {
> __le64 time;
> __u64 client_chal; /* random */
> __u32 reserved2;
> - struct ntlmssp2_name names[2];
> /* array of name entries could follow ending in minimum 4 byte struct */
> } __attribute__((packed));
>
> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
> index f5369e7..0621a72 100644
> --- a/fs/cifs/connect.c
> +++ b/fs/cifs/connect.c
> @@ -1768,6 +1768,8 @@ cifs_get_smb_ses(struct TCP_Server_Info *server, struct smb_vol *volume_info)
> if (ses == NULL)
> goto get_ses_fail;
>
> + ses->tilen = 0;
> + ses->tiblob = NULL;
> /* new SMB session uses our server ref */
> ses->server = server;
> if (server->addr.sockAddr6.sin6_family == AF_INET6)
> diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c
> index 0a57cb7..756f410 100644
> --- a/fs/cifs/sess.c
> +++ b/fs/cifs/sess.c
> @@ -383,6 +383,9 @@ static int decode_ascii_ssetup(char **pbcc_area, int bleft,
> static int decode_ntlmssp_challenge(char *bcc_ptr, int blob_len,
> struct cifsSesInfo *ses)
> {
> + unsigned int tioffset; /* challenge message target info area */
> + unsigned int tilen; /* challenge message target info area length */
> +
> CHALLENGE_MESSAGE *pblob = (CHALLENGE_MESSAGE *)bcc_ptr;
>
> if (blob_len < sizeof(CHALLENGE_MESSAGE)) {
> @@ -405,6 +408,20 @@ static int decode_ntlmssp_challenge(char *bcc_ptr, int blob_len,
> /* BB spec says that if AvId field of MsvAvTimestamp is populated then
> we must set the MIC field of the AUTHENTICATE_MESSAGE */
>
> + ses->server->ntlmssp.server_flags = le32_to_cpu(pblob->NegotiateFlags);
> +
> + tioffset = cpu_to_le16(pblob->TargetInfoArray.BufferOffset);
> + tilen = cpu_to_le16(pblob->TargetInfoArray.Length);
> + ses->tilen = tilen;
> + if (ses->tilen) {
> + ses->tiblob = kmalloc(tilen, GFP_KERNEL);
> + if (!ses->tiblob) {
> + cERROR(1, "Challenge target info allocation failure");
> + return -ENOMEM;
> + }
> + memcpy(ses->tiblob, bcc_ptr + tioffset, ses->tilen);
> + }
> +
> return 0;
> }
>
> @@ -533,6 +550,7 @@ static int build_ntlmssp_auth_blob(unsigned char *pbuffer,
> sec_blob->SessionKey.BufferOffset = cpu_to_le32(tmp - pbuffer);
> sec_blob->SessionKey.Length = 0;
> sec_blob->SessionKey.MaximumLength = 0;
> +
> return tmp - pbuffer;
> }
>
--
Jeff Layton <jlayton@xxxxxxxxx>
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