[CIFS] when not using unix extensions, check for and set ATTR_READONLY on create and mkdir

When creating a directory on a CIFS share without POSIX extensions,
and the given mode has no write bits set, set the ATTR_READONLY bit.

When creating a file, set ATTR_READONLY if the create mode has no write
bits set and we're not using unix extensions.

There are some comments about this being problematic due to the VFS
splitting creates into 2 parts. I'm not sure what that's actually
talking about, but I'm assuming that it has something to do with how
mknod is implemented. In the simple case where we have no unix
extensions and we're just creating a regular file, there's no reason
we can't set ATTR_READONLY.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 13 insertions, 3 deletions

diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index 6ed775986be9..e4e0078a0526 100644
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -119,6 +119,7 @@ cifs_create(struct inode *inode, struct dentry *direntry, int mode,
 {
         int rc = -ENOENT;
         int xid;
+        int create_options = CREATE_NOT_DIR;
         int oplock = 0;
         int desiredAccess = GENERIC_READ | GENERIC_WRITE;
         __u16 fileHandle;
@@ -176,9 +177,19 @@ cifs_create(struct inode *inode, struct dentry *direntry, int mode,
                 FreeXid(xid);
                 return -ENOMEM;
         }
+
+        mode &= ~current->fs->umask;
+
+        /*
+         * if we're not using unix extensions, see if we need to set
+         * ATTR_READONLY on the create call
+         */
+        if (!pTcon->unix_ext && (mode & S_IWUGO) == 0)
+                create_options |= CREATE_OPTION_READONLY;
+
         if (cifs_sb->tcon->ses->capabilities & CAP_NT_SMBS)
                 rc = CIFSSMBOpen(xid, pTcon, full_path, disposition,
-                         desiredAccess, CREATE_NOT_DIR,
+                         desiredAccess, create_options,
                          &fileHandle, &oplock, buf, cifs_sb->local_nls,
                          cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
         else
@@ -187,7 +198,7 @@ cifs_create(struct inode *inode, struct dentry *direntry, int mode,
         if (rc == -EIO) {
                 /* old server, retry the open legacy style */
                 rc = SMBLegacyOpen(xid, pTcon, full_path, disposition,
-                        desiredAccess, CREATE_NOT_DIR,
+                        desiredAccess, create_options,
                         &fileHandle, &oplock, buf, cifs_sb->local_nls,
                         cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
         }
@@ -197,7 +208,6 @@ cifs_create(struct inode *inode, struct dentry *direntry, int mode,
                 /* If Open reported that we actually created a file
                 then we now have to set the mode if possible */
                 if ((pTcon->unix_ext) && (oplock & CIFS_CREATE_ACTION)) {
-                        mode &= ~current->fs->umask;
                         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SET_UID) {
                                 CIFSSMBUnixSetPerms(xid, pTcon, full_path, mode,
                                         (__u64)current->fsuid,