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cifs: Fix validation of signed data in smb3+ 

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 14:52:23 -03:00 committed by Steve French
parent 696e420bb2
commit 27c32b49c3
1 changed files with 25 additions and 6 deletions
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31
fs/cifs/smb2transport.c
View File

@ -408,12 +408,14 @@ generate_smb311signingkey(struct cifs_ses *ses)
int
smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
{
int rc = 0;
int rc;
unsigned char smb3_signature[SMB2_CMACAES_SIZE];
unsigned char *sigptr = smb3_signature;
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.sdesccmacaes->shash;
struct smb_rqst drqst;
ses = smb2_find_smb_ses(server, shdr->SessionId);
if (!ses) {
@ -425,8 +427,7 @@ smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
memset(shdr->Signature, 0x0, SMB2_SIGNATURE_SIZE);
rc = crypto_shash_setkey(server->secmech.cmacaes,
ses->smb3signingkey, SMB2_CMACAES_SIZE);
ses->smb3signingkey, SMB2_CMACAES_SIZE);
if (rc) {
cifs_dbg(VFS, "%s: Could not set key for cmac aes\n", __func__);
return rc;
@ -437,15 +438,33 @@ smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
* so unlike smb2 case we do not have to check here if secmech are
* initialized
*/
rc = crypto_shash_init(&server->secmech.sdesccmacaes->shash);
rc = crypto_shash_init(shash);
if (rc) {
cifs_dbg(VFS, "%s: Could not init cmac aes\n", __func__);
return rc;
}
rc = __cifs_calc_signature(rqst, server, sigptr,
&server->secmech.sdesccmacaes->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);