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authorPaulo Alcantara <paulo@paulo.ac>2018-06-23 14:52:23 -0300
committerSteve French <stfrench@microsoft.com>2018-07-05 13:48:24 -0500
commit27c32b49c3dbfe1e5f57d2b61823bf9474ae0875 (patch)
tree1a520e0ee9a1a4cb5e49c06f3c3c825b0bc3b83d
parent696e420bb2a6624478105651d5368d45b502b324 (diff)
cifs: Fix validation of signed data in smb3+
Fixes: c713c8770fa5 ("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>
-rw-r--r--fs/cifs/smb2transport.c31
1 files changed, 25 insertions, 6 deletions
diff --git a/fs/cifs/smb2transport.c b/fs/cifs/smb2transport.c
index 50592976dcb4..1af46ca5a951 100644
--- a/fs/cifs/smb2transport.c
+++ b/fs/cifs/smb2transport.c
@@ -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);