nfsd: make V4ROOT exports read-only

I can't see any use for writeable V4ROOT exports.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

1 files changed, 11 insertions, 4 deletions

diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
index 18ac20ffedd2..7d5ba1b0ffcf 100644
--- a/fs/nfsd/export.c
+++ b/fs/nfsd/export.c
@@ -355,7 +355,7 @@ static struct svc_export *svc_export_update(struct svc_export *new,
                                             struct svc_export *old);
 static struct svc_export *svc_export_lookup(struct svc_export *);
 
-static int check_export(struct inode *inode, int flags, unsigned char *uuid)
+static int check_export(struct inode *inode, int *flags, unsigned char *uuid)
 {
 
         /*
@@ -367,6 +367,13 @@ static int check_export(struct inode *inode, int flags, unsigned char *uuid)
             !S_ISREG(inode->i_mode))
                 return -ENOTDIR;
 
+        /*
+         * Mountd should never pass down a writeable V4ROOT export, but,
+         * just to make sure:
+         */
+        if (*flags & NFSEXP_V4ROOT)
+                *flags |= NFSEXP_READONLY;
+
         /* There are two requirements on a filesystem to be exportable.
          * 1:  We must be able to identify the filesystem from a number.
          *       either a device number (so FS_REQUIRES_DEV needed)
@@ -375,7 +382,7 @@ static int check_export(struct inode *inode, int flags, unsigned char *uuid)
          *       This means that s_export_op must be set.
          */
         if (!(inode->i_sb->s_type->fs_flags & FS_REQUIRES_DEV) &&
-            !(flags & NFSEXP_FSID) &&
+            !(*flags & NFSEXP_FSID) &&
             uuid == NULL) {
                 dprintk("exp_export: export of non-dev fs without fsid\n");
                 return -EINVAL;
@@ -590,7 +597,7 @@ static int svc_export_parse(struct cache_detail *cd, char *mesg, int mlen)
                                 goto out4;
                 }
 
-                err = check_export(exp.ex_path.dentry->d_inode, exp.ex_flags,
+                err = check_export(exp.ex_path.dentry->d_inode, &exp.ex_flags,
                                    exp.ex_uuid);
                 if (err)
                         goto out4;
@@ -1029,7 +1036,7 @@ exp_export(struct nfsctl_export *nxp)
                 goto finish;
         }
 
-        err = check_export(path.dentry->d_inode, nxp->ex_flags, NULL);
+        err = check_export(path.dentry->d_inode, &nxp->ex_flags, NULL);
         if (err) goto finish;
 
         err = -ENOMEM;