smb3: Fix rmdir compounding regression to strict servers

Some servers require that the setinfo matches the exact size,
and in this case compounding changes introduced by
commit c2e0fe3f5aae ("cifs: make rmdir() use compounding")
caused us to send 8 bytes (padded length) instead of 1 byte
(the size of the structure).  See MS-FSCC section 2.4.11.

Fixing this when we send a SET_INFO command for delete file
disposition, then ends up as an iov of a single byte but this
causes problems with SMB3 and encryption.

To avoid this, instead of creating a one byte iov for the disposition value
and then appending an additional iov with a 7 byte padding we now handle
this as a single 8 byte iov containing both the disposition byte as well as
the padding in one single buffer.

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Acked-by: Paulo Alcantara <palcantara@suse.de>

1 files changed, 15 insertions, 8 deletions

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 225fec1cfa67..e25c7aade98a 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -1194,7 +1194,7 @@ smb2_ioctl_query_info(const unsigned int xid,
 	rc = SMB2_open_init(tcon, &rqst[0], &oplock, &oparms, path);
 	if (rc)
 		goto iqinf_exit;
-	smb2_set_next_command(ses->server, &rqst[0]);
+	smb2_set_next_command(ses->server, &rqst[0], 0);
 
 	/* Query */
 	memset(&qi_iov, 0, sizeof(qi_iov));
@@ -1208,7 +1208,7 @@ smb2_ioctl_query_info(const unsigned int xid,
 				  qi.output_buffer_length, buffer);
 	if (rc)
 		goto iqinf_exit;
-	smb2_set_next_command(ses->server, &rqst[1]);
+	smb2_set_next_command(ses->server, &rqst[1], 0);
 	smb2_set_related(&rqst[1]);
 
 	/* Close */
@@ -1761,16 +1761,23 @@ smb2_set_related(struct smb_rqst *rqst)
 char smb2_padding[7] = {0, 0, 0, 0, 0, 0, 0};
 
 void
-smb2_set_next_command(struct TCP_Server_Info *server, struct smb_rqst *rqst)
+smb2_set_next_command(struct TCP_Server_Info *server, struct smb_rqst *rqst,
+		      bool has_space_for_padding)
 {
 	struct smb2_sync_hdr *shdr;
 	unsigned long len = smb_rqst_len(server, rqst);
 
 	/* SMB headers in a compound are 8 byte aligned. */
 	if (len & 7) {
-		rqst->rq_iov[rqst->rq_nvec].iov_base = smb2_padding;
-		rqst->rq_iov[rqst->rq_nvec].iov_len = 8 - (len & 7);
-		rqst->rq_nvec++;
+		if (has_space_for_padding) {
+			len = rqst->rq_iov[rqst->rq_nvec - 1].iov_len;
+			rqst->rq_iov[rqst->rq_nvec - 1].iov_len =
+				(len + 7) & ~7;
+		} else {
+			rqst->rq_iov[rqst->rq_nvec].iov_base = smb2_padding;
+			rqst->rq_iov[rqst->rq_nvec].iov_len = 8 - (len & 7);
+			rqst->rq_nvec++;
+		}
 		len = smb_rqst_len(server, rqst);
 	}
 
@@ -1820,7 +1827,7 @@ smb2_queryfs(const unsigned int xid, struct cifs_tcon *tcon,
 	rc = SMB2_open_init(tcon, &rqst[0], &oplock, &oparms, &srch_path);
 	if (rc)
 		goto qfs_exit;
-	smb2_set_next_command(server, &rqst[0]);
+	smb2_set_next_command(server, &rqst[0], 0);
 
 	memset(&qi_iov, 0, sizeof(qi_iov));
 	rqst[1].rq_iov = qi_iov;
@@ -1833,7 +1840,7 @@ smb2_queryfs(const unsigned int xid, struct cifs_tcon *tcon,
 				  NULL);
 	if (rc)
 		goto qfs_exit;
-	smb2_set_next_command(server, &rqst[1]);
+	smb2_set_next_command(server, &rqst[1], 0);
 	smb2_set_related(&rqst[1]);
 
 	memset(&close_iov, 0, sizeof(close_iov));