From 365ffd61728347b94a149c5e0342c3b631ea8c45 Mon Sep 17 00:00:00 2001 From: Sachin Prabhu Date: Wed, 20 Apr 2011 13:09:35 +0100 Subject: [PATCH] Open with O_CREAT flag set fails to open existing files on non writable directories commit 1574dff8996ab1ed92c09012f8038b5566fce313 upstream. An open on a NFS4 share using the O_CREAT flag on an existing file for which we have permissions to open but contained in a directory with no write permissions will fail with EACCES. A tcpdump shows that the client had set the open mode to UNCHECKED which indicates that the file should be created if it doesn't exist and encountering an existing flag is not an error. Since in this case the file exists and can be opened by the user, the NFS server is wrong in attempting to check create permissions on the parent directory. The patch adds a conditional statement to check for create permissions only if the file doesn't exist. Signed-off-by: Sachin S. Prabhu Signed-off-by: J. Bruce Fields Signed-off-by: Greg Kroah-Hartman Signed-off-by: Willy Tarreau --- fs/nfsd/vfs.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 81284c6ce30e..6cc85951533e 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -1334,7 +1334,7 @@ nfsd_create_v3(struct svc_rqst *rqstp, struct svc_fh *fhp, goto out; if (!(iap->ia_valid & ATTR_MODE)) iap->ia_mode = 0; - err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_CREATE); + err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_EXEC); if (err) goto out; @@ -1356,6 +1356,13 @@ nfsd_create_v3(struct svc_rqst *rqstp, struct svc_fh *fhp, if (IS_ERR(dchild)) goto out_nfserr; + /* If file doesn't exist, check for permissions to create one */ + if (!dchild->d_inode) { + err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_CREATE); + if (err) + goto out; + } + err = fh_compose(resfhp, fhp->fh_export, dchild, fhp); if (err) goto out; -- 2.39.5