From 8de8c4608fe9edc046c31bf82b2b7ebc1daae015 Mon Sep 17 00:00:00 2001 From: Paulo Alcantara Date: Sat, 23 Jun 2018 14:52:24 -0300 Subject: [PATCH] cifs: Fix validation of signed data in smb2 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 Reviewed-by: Ronnie Sahlberg Signed-off-by: Steve French --- 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); -- 2.30.2