nfsd4: fix READ permission checking
In the case we already have a struct file (derived from a stateid), we
still need to do permission-checking; otherwise an unauthorized user
could gain access to a file by sniffing or guessing somebody else's
stateid.
Cc: stable@vger.kernel.org
Fixes: dc97618ddda9 "nfsd4: separate splice and readv cases"
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index cea6c52..a45032c 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -3422,6 +3422,7 @@
unsigned long maxcount;
struct xdr_stream *xdr = &resp->xdr;
struct file *file = read->rd_filp;
+ struct svc_fh *fhp = read->rd_fhp;
int starting_len = xdr->buf->len;
struct raparms *ra;
__be32 *p;
@@ -3445,12 +3446,15 @@
maxcount = min_t(unsigned long, maxcount, (xdr->buf->buflen - xdr->buf->len));
maxcount = min_t(unsigned long, maxcount, read->rd_length);
- if (!read->rd_filp) {
+ if (read->rd_filp)
+ err = nfsd_permission(resp->rqstp, fhp->fh_export,
+ fhp->fh_dentry,
+ NFSD_MAY_READ|NFSD_MAY_OWNER_OVERRIDE);
+ else
err = nfsd_get_tmp_read_open(resp->rqstp, read->rd_fhp,
&file, &ra);
- if (err)
- goto err_truncate;
- }
+ if (err)
+ goto err_truncate;
if (file->f_op->splice_read && test_bit(RQ_SPLICE_OK, &resp->rqstp->rq_flags))
err = nfsd4_encode_splice_read(resp, read, file, maxcount);