[ 050/123] NFS: Fix access to suid/sgid executables

Greg Kroah-Hartman
2013-01-09T21:20:08Z

From: Weston Andros Adamson <dros@netapp.com>

commit f8d9a897d4384b77f13781ea813156568f68b83e upstream.

nfs_open_permission_mask() should only check MAY_EXEC for files that
are opened with __FMODE_EXEC.

Also fix NFSv4 access-in-open path in a similar way -- openflags must be
used because fmode will not always have FMODE_EXEC set.

This patch fixes https://bugzilla.kernel.org/show_bug.cgi?id=49101

Signed-off-by: Weston Andros Adamson <dros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/nfs/dir.c | 16 ++++++++++------
fs/nfs/nfs4proc.c | 18 +++++++++++-------
2 files changed, 21 insertions(+), 13 deletions(-)

--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -2148,12 +2148,16 @@ static int nfs_open_permission_mask(int
{
int mask = 0;

- if ((openflags & O_ACCMODE) != O_WRONLY)
- mask |= MAY_READ;
- if ((openflags & O_ACCMODE) != O_RDONLY)
- mask |= MAY_WRITE;
- if (openflags & __FMODE_EXEC)
- mask |= MAY_EXEC;
+ if (openflags & __FMODE_EXEC) {
+ /* ONLY check exec rights */
+ mask = MAY_EXEC;
+ } else {
+ if ((openflags & O_ACCMODE) != O_WRONLY)
+ mask |= MAY_READ;
+ if ((openflags & O_ACCMODE) != O_RDONLY)
+ mask |= MAY_WRITE;
+ }
+
return mask;
}

--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -1721,7 +1721,8 @@ static int _nfs4_recover_proc_open(struc

static int nfs4_opendata_access(struct rpc_cred *cred,
struct nfs4_opendata *opendata,
- struct nfs4_state *state, fmode_t fmode)
+ struct nfs4_state *state, fmode_t fmode,
+ int openflags)
{
struct nfs_access_entry cache;
u32 mask;
@@ -1733,11 +1734,14 @@ static int nfs4_opendata_access(struct r

mask = 0;
/* don't check MAY_WRITE - a newly created file may not have
- * write mode bits, but POSIX allows the creating process to write */
- if (fmode & FMODE_READ)
- mask |= MAY_READ;
- if (fmode & FMODE_EXEC)
- mask |= MAY_EXEC;
+ * write mode bits, but POSIX allows the creating process to write.
+ * use openflags to check for exec, because fmode won't
+ * always have FMODE_EXEC set when file open for exec. */
+ if (openflags & __FMODE_EXEC) {
+ /* ONLY check for exec rights */
+ mask = MAY_EXEC;
+ } else if (fmode & FMODE_READ)
+ mask = MAY_READ;

cache.cred = cred;
cache.jiffies = jiffies;
@@ -2009,7 +2013,7 @@ static int _nfs4_do_open(struct inode *d
if (server->caps & NFS_CAP_POSIX_LOCK)
set_bit(NFS_STATE_POSIX_LOCKS, &state->flags);

- status = nfs4_opendata_access(cred, opendata, state, fmode);
+ status = nfs4_opendata_access(cred, opendata, state, fmode, flags);
if (status != 0)
goto err_opendata_put;