[CIFS] enable parsing for transport encryption mount parm

Samba now supports transport encryption on particular exports
(mounted tree ids can be encrypted for servers which support the
unix extensions).  This adds parsing support to cifs mount
option parsing for this.
Signed-off-by: Steve French <sfrench@us.ibm.com>

fs/cifs/README

@@ -483,6 +483,11 @@ A partial list of the supported mount options follows:
  sign           Must use packet signing (helps avoid unwanted data modification
 		by intermediate systems in the route).  Note that signing
 		does not work with lanman or plaintext authentication.
+ seal           Must seal (encrypt) all data on this mounted share before
+		sending on the network.  Requires support for Unix Extensions.
+		Note that this differs from the sign mount option in that it
+		causes encryption of data sent over this mounted share but other
+		shares mounted to the same server are unaffected.
  sec            Security mode.  Allowed values are:
 			none	attempt to connection as a null user (no name)
 			krb5    Use Kerberos version 5 authentication

fs/cifs/cifsglob.h

@@ -281,6 +281,7 @@ struct cifsTconInfo {
 	bool ipc:1;		/* set if connection to IPC$ eg for RPC/PIPES */
 	bool retry:1;
 	bool nocase:1;
+	bool seal:1;      /* transport encryption for this mounted share */
 	bool unix_ext:1;  /* if false disable Linux extensions to CIFS protocol
 				for this mount even if server would support */
 	/* BB add field for back pointer to sb struct(s)? */

fs/cifs/connect.c

@@ -60,7 +60,7 @@ struct smb_vol {
 	char *domainname;
 	char *UNC;
 	char *UNCip;
-	char *in6_addr;  /* ipv6 address as human readable form of in6_addr */
+	char *in6_addr;   /* ipv6 address as human readable form of in6_addr */
 	char *iocharset;  /* local code page for mapping to and from Unicode */
 	char source_rfc1001_name[16]; /* netbios name of client */
 	char target_rfc1001_name[16]; /* netbios name of server for Win9x/ME */
@@ -82,13 +82,14 @@ struct smb_vol {
 	bool no_xattr:1;   /* set if xattr (EA) support should be disabled*/
 	bool server_ino:1; /* use inode numbers from server ie UniqueId */
 	bool direct_io:1;
-	bool remap:1;     /* set to remap seven reserved chars in filenames */
-	bool posix_paths:1;   /* unset to not ask for posix pathnames. */
+	bool remap:1;      /* set to remap seven reserved chars in filenames */
+	bool posix_paths:1; /* unset to not ask for posix pathnames. */
 	bool no_linux_ext:1;
 	bool sfu_emul:1;
-	bool nullauth:1; /* attempt to authenticate with null user */
-	unsigned nocase;     /* request case insensitive filenames */
-	unsigned nobrl;      /* disable sending byte range locks to srv */
+	bool nullauth:1;   /* attempt to authenticate with null user */
+	bool nocase:1;     /* request case insensitive filenames */
+	bool nobrl:1;      /* disable sending byte range locks to srv */
+	bool seal:1;       /* request transport encryption on share */
 	unsigned int rsize;
 	unsigned int wsize;
 	unsigned int sockopt;
@@ -1273,8 +1274,12 @@ cifs_parse_mount_options(char *options, const char *devname,
 			vol->no_psx_acl = 1;
 		} else if (strnicmp(data, "sign", 4) == 0) {
 			vol->secFlg |= CIFSSEC_MUST_SIGN;
-/*		} else if (strnicmp(data, "seal",4) == 0) {
-			vol->secFlg |= CIFSSEC_MUST_SEAL; */
+		} else if (strnicmp(data, "seal", 4) == 0) {
+			/* we do not do the following in secFlags because seal
+			   is a per tree connection (mount) not a per socket
+			   or per-smb connection option in the protocol */
+			/* vol->secFlg |= CIFSSEC_MUST_SEAL; */
+			vol->seal = 1;
 		} else if (strnicmp(data, "direct", 6) == 0) {
 			vol->direct_io = 1;
 		} else if (strnicmp(data, "forcedirectio", 13) == 0) {
@@ -2126,6 +2131,9 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb,
 			   for the retry flag is used */
 			tcon->retry = volume_info.retry;
 			tcon->nocase = volume_info.nocase;
+			if (tcon->seal != volume_info.seal)
+				cERROR(1, ("transport encryption setting "
+					   "conflicts with existing tid"));
 		} else {
 			tcon = tconInfoAlloc();
 			if (tcon == NULL)
@@ -2159,6 +2167,7 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb,
 					atomic_inc(&pSesInfo->inUse);
 					tcon->retry = volume_info.retry;
 					tcon->nocase = volume_info.nocase;
+					tcon->seal = volume_info.seal;
 				}
 			}
 		}