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cifs: Fix validation of signed data in smb2

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Fixes: c713c8770f ("cifs: push rfc1002 generation down the stack")

We failed to validate signed data returned by the server because
__cifs_calc_signature() now expects to sign the actual data in iov but
we were also passing down the rfc1002 length.

Fix smb3_calc_signature() to calculate signature of rfc1002 length prior
to passing only the actual data iov[1-N] to __cifs_calc_signature(). In
addition, there are a few cases where no rfc1002 length is passed so we
make sure there's one (iov_len == 4).

Signed-off-by: Paulo Alcantara <palcantara@suse.de>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Paulo Alcantara 2018-06-23 14:52:24 -03:00 committed by Steve French
parent 27c32b49c3
commit 8de8c4608f
1 changed files with 24 additions and 4 deletions
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28
fs/cifs/smb2transport.c
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@ -173,6 +173,8 @@ smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
struct kvec *iov = rqst->rq_iov;
struct smb2_sync_hdr *shdr = (struct smb2_sync_hdr *)iov[0].iov_base;
struct cifs_ses *ses;
struct shash_desc *shash = &server->secmech.sdeschmacsha256->shash;
struct smb_rqst drqst;
ses = smb2_find_smb_ses(server, shdr->SessionId);
if (!ses) {
@ -190,21 +192,39 @@ smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
}
rc = crypto_shash_setkey(server->secmech.hmacsha256,
ses->auth_key.response, SMB2_NTLMV2_SESSKEY_SIZE);
ses->auth_key.response, SMB2_NTLMV2_SESSKEY_SIZE);
if (rc) {
cifs_dbg(VFS, "%s: Could not update with response\n", __func__);
return rc;
}
rc = crypto_shash_init(&server->secmech.sdeschmacsha256->shash);
rc = crypto_shash_init(shash);
if (rc) {
cifs_dbg(VFS, "%s: Could not init sha256", __func__);
return rc;
}
rc = __cifs_calc_signature(rqst, server, sigptr,
&server->secmech.sdeschmacsha256->shash);
/*
* For SMB2+, __cifs_calc_signature() expects to sign only the actual
* data, that is, iov[0] should not contain a rfc1002 length.
*
* Sign the rfc1002 length prior to passing the data (iov[1-N]) down to
* __cifs_calc_signature().
*/
drqst = *rqst;
if (drqst.rq_nvec >= 2 && iov[0].iov_len == 4) {
rc = crypto_shash_update(shash, iov[0].iov_base,
iov[0].iov_len);
if (rc) {
cifs_dbg(VFS, "%s: Could not update with payload\n",
__func__);
return rc;
}
drqst.rq_iov++;
drqst.rq_nvec--;
}
rc = __cifs_calc_signature(&drqst, server, sigptr, shash);
if (!rc)
memcpy(shdr->Signature, sigptr, SMB2_SIGNATURE_SIZE);