From: J. Bruce Fields Date: Mon, 15 Apr 2013 20:03:46 +0000 (-0400) Subject: nfsd: fix EXDEV checking in rename X-Git-Tag: firefly_0821_release~3680^2~488^2~14 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=aa387d6ce15330e09037947147c5a5a2ba42a0e8;p=firefly-linux-kernel-4.4.55.git nfsd: fix EXDEV checking in rename We again check for the EXDEV a little later on, so the first check is redundant. This check is also slightly racier, since a badly timed eviction from the export cache could leave us with the two fh_export pointers pointing to two different cache entries which each refer to the same underlying export. It's better to compare vfsmounts as the later check does, but that leaves a minor security hole in the case where the two exports refer to two different directories especially if (for example) they have different root-squashing options. So, compare ex_path.dentry too. Reported-by: Joe Habermann Signed-off-by: J. Bruce Fields --- diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 2b2e2396a869..84ce601d8063 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -1758,10 +1758,6 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen, tdentry = tfhp->fh_dentry; tdir = tdentry->d_inode; - err = (rqstp->rq_vers == 2) ? nfserr_acces : nfserr_xdev; - if (ffhp->fh_export != tfhp->fh_export) - goto out; - err = nfserr_perm; if (!flen || isdotent(fname, flen) || !tlen || isdotent(tname, tlen)) goto out; @@ -1802,6 +1798,8 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen, host_err = -EXDEV; if (ffhp->fh_export->ex_path.mnt != tfhp->fh_export->ex_path.mnt) goto out_dput_new; + if (ffhp->fh_export->ex_path.dentry != tfhp->fh_export->ex_path.dentry) + goto out_dput_new; host_err = nfsd_break_lease(odentry->d_inode); if (host_err)