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Commit 5c5fc09a authored by Trond Myklebust's avatar Trond Myklebust
Browse files

NFS: Ensure we revalidate attributes before using execute_ok() 



Donald Buczek reports that NFS clients can also report incorrect
results for access() due to lack of revalidation of attributes
before calling execute_ok().
Looking closely, it seems chdir() is afflicted with the same problem.

Fix is to ensure we call nfs_revalidate_inode_rcu() or
nfs_revalidate_inode() as appropriate before deciding to trust
execute_ok().

Reported-by: default avatarDonald Buczek <buczek@molgen.mpg.de>
Link: http://lkml.kernel.org/r/1451331530-3748-1-git-send-email-buczek@molgen.mpg.de


Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
parent 494f74a2

fs/nfs/dir.c

+16 −2
Original line number Diff line number Diff line
@@ -2432,6 +2432,20 @@ int nfs_may_open(struct inode *inode, struct rpc_cred *cred, int openflags) 
}

EXPORT_SYMBOL_GPL(nfs_may_open);



static int nfs_execute_ok(struct inode *inode, int mask)

{

	struct nfs_server *server = NFS_SERVER(inode);

	int ret;



	if (mask & MAY_NOT_BLOCK)

		ret = nfs_revalidate_inode_rcu(server, inode);

	else

		ret = nfs_revalidate_inode(server, inode);

	if (ret == 0 && !execute_ok(inode))

		ret = -EACCES;

	return ret;

}



int nfs_permission(struct inode *inode, int mask)

{

	struct rpc_cred *cred;
@@ -2484,8 +2498,8 @@ int nfs_permission(struct inode *inode, int mask) 
			res = PTR_ERR(cred);

	}

out:

	if (!res && (mask & MAY_EXEC) && !execute_ok(inode))

		res = -EACCES;

	if (!res && (mask & MAY_EXEC))

		res = nfs_execute_ok(inode, mask);



	dfprintk(VFS, "NFS: permission(%s/%lu), mask=0x%x, res=%d\n",

		inode->i_sb->s_id, inode->i_ino, mask, res);