lkml.org 
[lkml]   [2011]   [Nov]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[094/262] nfsd4: permit read opens of executable-only files
3.0-stable review patch.  If anyone has any objections, please let me know.

------------------
From: "J. Bruce Fields" <bfields@redhat.com>

commit a043226bc140a2c1dde162246d68a67e5043e6b2 upstream.

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>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
fs/nfsd/nfs4proc.c | 2 ++
fs/nfsd/vfs.c | 3 ++-
fs/nfsd/vfs.h | 1 +
3 files changed, 5 insertions(+), 1 deletion(-)
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -156,6 +156,8 @@ do_open_permission(struct svc_rqst *rqst
!(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)
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -2114,7 +2114,8 @@ nfsd_permission(struct svc_rqst *rqstp,

/* 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);

return err? nfserrno(err) : 0;
--- a/fs/nfsd/vfs.h
+++ b/fs/nfsd/vfs.h
@@ -25,6 +25,7 @@
#define NFSD_MAY_BYPASS_GSS_ON_ROOT 256
#define NFSD_MAY_NOT_BREAK_LEASE 512
#define NFSD_MAY_BYPASS_GSS 1024
+#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)



\
 
 \ /
  Last update: 2011-11-10 06:13    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site