nfsd: fix "insecure" export option

[safe/jmp/linux-2.6] / fs / nfsd / nfsfh.c

diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c
index 951938d..55c8e63 100644 (file)
--- a/fs/nfsd/nfsfh.c
+++ b/fs/nfsd/nfsfh.c
@@ -1,6 +1,4 @@
 /*
- * linux/fs/nfsd/nfsfh.c
- *
  * NFS server file handle treatment.
  *
  * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
@@ -91,7 +89,7 @@ static __be32 nfsd_setuser_and_check_port(struct svc_rqst *rqstp,
        int flags = nfsexp_flags(rqstp, exp);
 
        /* Check if the request originated from a secure port. */
-       if (!rqstp->rq_secure && (flags & NFSEXP_INSECURE_PORT)) {
+       if (!rqstp->rq_secure && !(flags & NFSEXP_INSECURE_PORT)) {
                RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
                dprintk(KERN_WARNING
                       "nfsd: request from insecure port %s!\n",
@@ -103,6 +101,36 @@ static __be32 nfsd_setuser_and_check_port(struct svc_rqst *rqstp,
        return nfserrno(nfsd_setuser(rqstp, exp));
 }
 
+static inline __be32 check_pseudo_root(struct svc_rqst *rqstp,
+       struct dentry *dentry, struct svc_export *exp)
+{
+       if (!(exp->ex_flags & NFSEXP_V4ROOT))
+               return nfs_ok;
+       /*
+        * v2/v3 clients have no need for the V4ROOT export--they use
+        * the mount protocl instead; also, further V4ROOT checks may be
+        * in v4-specific code, in which case v2/v3 clients could bypass
+        * them.
+        */
+       if (!nfsd_v4client(rqstp))
+               return nfserr_stale;
+       /*
+        * We're exposing only the directories and symlinks that have to be
+        * traversed on the way to real exports:
+        */
+       if (unlikely(!S_ISDIR(dentry->d_inode->i_mode) &&
+                    !S_ISLNK(dentry->d_inode->i_mode)))
+               return nfserr_stale;
+       /*
+        * A pseudoroot export gives permission to access only one
+        * single directory; the kernel has to make another upcall
+        * before granting access to anything else under it:
+        */
+       if (unlikely(dentry != exp->ex_path.dentry))
+               return nfserr_stale;
+       return nfs_ok;
+}
+
 /*
  * Use the given filehandle to look up the corresponding export and
  * dentry.  On success, the results are used to set fh_export and
@@ -299,6 +327,10 @@ fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access)
         *        (for example, if different id-squashing options are in
         *        effect on the new filesystem).
         */
+       error = check_pseudo_root(rqstp, dentry, exp);
+       if (error)
+               goto out;
+
        error = nfsd_setuser_and_check_port(rqstp, exp);
        if (error)
                goto out;