[CIFS] When mandatory encryption on share, fail mount

    When mandatory encryption is configured in samba server on a
    share (smb.conf parameter "smb encrypt = mandatory") the
    server will hang up the tcp session when we try to send
    the first frame after the tree connect if it is not a
    QueryFSUnixInfo, this causes cifs mount to hang (it must
    be killed with ctl-c).  Move the QueryFSUnixInfo call
    earlier in the mount sequence, and check whether the SetFSUnixInfo
    fails due to mandatory encryption so we can return a sensible
    error (EACCES) on mount.

    In a future patch (for 2.6.40) we will support mandatory
    encryption.

CC: Stable <stable@kernel.org>
Reviewed-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 22 insertions, 9 deletions

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 2e7a79cd2b93..581654fb174d 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -2530,7 +2530,7 @@ void reset_cifs_unix_caps(int xid, struct cifsTconInfo *tcon,
 
         if (!CIFSSMBQFSUnixInfo(xid, tcon)) {
                 __u64 cap = le64_to_cpu(tcon->fsUnixInfo.Capability);
-
+                cFYI(1, "unix caps which server supports %lld", cap);
                 /* check for reconnect case in which we do not
                    want to change the mount behavior if we can avoid it */
                 if (vol_info == NULL) {
@@ -2548,6 +2548,9 @@ void reset_cifs_unix_caps(int xid, struct cifsTconInfo *tcon,
                         }
                 }
 
+                if (cap & CIFS_UNIX_TRANSPORT_ENCRYPTION_MANDATORY_CAP)
+                        cERROR(1, "per-share encryption not supported yet");
+
                 cap &= CIFS_UNIX_CAP_MASK;
                 if (vol_info && vol_info->no_psx_acl)
                         cap &= ~CIFS_UNIX_POSIX_ACL_CAP;
@@ -2596,6 +2599,10 @@ void reset_cifs_unix_caps(int xid, struct cifsTconInfo *tcon,
                         cFYI(1, "very large read cap");
                 if (cap & CIFS_UNIX_LARGE_WRITE_CAP)
                         cFYI(1, "very large write cap");
+                if (cap & CIFS_UNIX_TRANSPORT_ENCRYPTION_CAP)
+                        cFYI(1, "transport encryption cap");
+                if (cap & CIFS_UNIX_TRANSPORT_ENCRYPTION_MANDATORY_CAP)
+                        cFYI(1, "mandatory transport encryption cap");
 #endif /* CIFS_DEBUG2 */
                 if (CIFSSMBSetFSUnixInfo(xid, tcon, cap)) {
                         if (vol_info == NULL) {
@@ -3022,20 +3029,26 @@ try_mount_again:
                 goto remote_path_check;
         }
 
-        /* do not care if following two calls succeed - informational */
-        if (!tcon->ipc) {
-                CIFSSMBQFSDeviceInfo(xid, tcon);
-                CIFSSMBQFSAttributeInfo(xid, tcon);
-        }
-
         /* tell server which Unix caps we support */
-        if (tcon->ses->capabilities & CAP_UNIX)
+        if (tcon->ses->capabilities & CAP_UNIX) {
                 /* reset of caps checks mount to see if unix extensions
                    disabled for just this mount */
                 reset_cifs_unix_caps(xid, tcon, sb, volume_info);
-        else
+                if ((tcon->ses->server->tcpStatus == CifsNeedReconnect) &&
+                    (le64_to_cpu(tcon->fsUnixInfo.Capability) &
+                     CIFS_UNIX_TRANSPORT_ENCRYPTION_MANDATORY_CAP)) {
+                        rc = -EACCES;
+                        goto mount_fail_check;
+                }
+        } else
                 tcon->unix_ext = 0; /* server does not support them */
 
+        /* do not care if following two calls succeed - informational */
+        if (!tcon->ipc) {
+                CIFSSMBQFSDeviceInfo(xid, tcon);
+                CIFSSMBQFSAttributeInfo(xid, tcon);
+        }
+
         /* convert forward to back slashes in prepath here if needed */
         if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS) == 0)
                 convert_delimiter(cifs_sb->prepath, CIFS_DIR_SEP(cifs_sb));