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 lenght is passed so we
make sure there's one (iov_len == 4).
Signed-off-by: Paulo Alcantara <palcantara@xxxxxxx>
---
fs/cifs/smb2transport.c | 28 ++++++++++++++++++++++++----
1 file changed, 24 insertions(+), 4 deletions(-)
diff --git a/fs/cifs/smb2transport.c b/fs/cifs/smb2transport.c
index 1af46ca5a951..719d55e63d88 100644
--- a/fs/cifs/smb2transport.c
+++ b/fs/cifs/smb2transport.c
@@ -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);
--
2.17.1
--
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