From 074ee05b34ae66eb3f7a335d17f7374c3a972f0c Mon Sep 17 00:00:00 2001
From: "J. Bruce Fields" <bfields@redhat.com>
Date: Thu, 25 Aug 2011 10:48:39 -0400
Subject: [PATCH] nfsd4: permit read opens of executable-only files
A client that wants to execute a file must be able to read it. Read
opens over nfs are therefore implicitly allowed for executable files
even when those files are not readable.
NFSv2/v3 get this right by using a passed-in NFSD_MAY_OWNER_OVERRIDE on
read requests, but NFSv4 has gotten this wrong ever since
dc730e173785e29b297aa605786c94adaffe2544 "nfsd4: fix owner-override on
open", when we realized that the file owner shouldn't override
permissions on non-reclaim NFSv4 opens.
So we can't use NFSD_MAY_OWNER_OVERRIDE to tell nfsd_permission to allow
reads of executable files.
So, do the same thing we do whenever we encounter another weird NFS
permission nit: define yet another NFSD_MAY_* flag.
The industry's future standardization on 128-bit processors will be
motivated primarily by the need for integers with enough bits for all
the NFSD_MAY_* flags.
Reported-by: Leonardo Borda <leonardoborda@gmail.com>
Cc: stable@kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
(cherry picked from commit a043226bc140a2c1dde162246d68a67e5043e6b2)
BugLink: http://bugs.launchpad.net/bugs/833300
Conflicts:
fs/nfsd/vfs.h
Signed-off-by: Chris J Arges <chris.j.arges@canonical.com>
---
fs/nfsd/nfs4proc.c | 2 ++
fs/nfsd/vfs.c | 3 ++-
include/linux/nfsd/nfsd.h | 1 +
3 files changed, 5 insertions(+), 1 deletions(-)
@@ -166,6 +166,8 @@ do_open_permission(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nfs
!(open->op_share_access & NFS4_SHARE_ACCESS_WRITE))
return nfserr_inval;
+ accmode |= NFSD_MAY_READ_IF_EXEC;
+
if (open->op_share_access & NFS4_SHARE_ACCESS_READ)
accmode |= NFSD_MAY_READ;
if (open->op_share_access & NFS4_SHARE_ACCESS_WRITE)
@@ -2118,7 +2118,8 @@ nfsd_permission(struct svc_rqst *rqstp, struct svc_export *exp,
/* Allow read access to binaries even when mode 111 */
if (err == -EACCES && S_ISREG(inode->i_mode) &&
- acc == (NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE))
+ (acc == (NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE) ||
+ acc == (NFSD_MAY_READ | NFSD_MAY_READ_IF_EXEC)))
err = inode_permission(inode, MAY_EXEC);
if (err)
goto nfsd_out;
@@ -38,6 +38,7 @@
#define NFSD_MAY_OWNER_OVERRIDE 64
#define NFSD_MAY_LOCAL_ACCESS 128 /* IRIX doing local access check on device special file*/
#define NFSD_MAY_BYPASS_GSS_ON_ROOT 256
+#define NFSD_MAY_READ_IF_EXEC 2048
#define NFSD_MAY_CREATE (NFSD_MAY_EXEC|NFSD_MAY_WRITE)
#define NFSD_MAY_REMOVE (NFSD_MAY_EXEC|NFSD_MAY_WRITE|NFSD_MAY_TRUNC)
--
1.7.5.4