NLM: Shrink the maximum request size of NLM4 requests
NLM version 4 requests estimate the call and reply header sizes rather
conservatively, using the very maximum size allowed in the protocol even
though Linux always uses only a small fraction of the allowable space.
Reduce the size of caller and lock arguments to conserve RPC buffer space
while XDR encoding NLM4 arguments. Add compile-time checks to ensure the
hostname string won't overflow NLM protocol maximums.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/lockd/xdr.c b/fs/lockd/xdr.c
index 34dae5d..6aac4b2 100644
--- a/fs/lockd/xdr.c
+++ b/fs/lockd/xdr.c
@@ -510,17 +510,20 @@
return 0;
}
+#if (NLMCLNT_OHSIZE > XDR_MAX_NETOBJ)
+# error "NLM host name cannot be larger than XDR_MAX_NETOBJ!"
+#endif
+
/*
* Buffer requirements for NLM
*/
#define NLM_void_sz 0
#define NLM_cookie_sz 1+XDR_QUADLEN(NLM_MAXCOOKIELEN)
-#define NLM_caller_sz 1+XDR_QUADLEN(sizeof(utsname()->nodename))
-#define NLM_netobj_sz 1+XDR_QUADLEN(XDR_MAX_NETOBJ)
-/* #define NLM_owner_sz 1+XDR_QUADLEN(NLM_MAXOWNER) */
+#define NLM_caller_sz 1+XDR_QUADLEN(NLMCLNT_OHSIZE)
+#define NLM_owner_sz 1+XDR_QUADLEN(NLMCLNT_OHSIZE)
#define NLM_fhandle_sz 1+XDR_QUADLEN(NFS2_FHSIZE)
-#define NLM_lock_sz 3+NLM_caller_sz+NLM_netobj_sz+NLM_fhandle_sz
-#define NLM_holder_sz 4+NLM_netobj_sz
+#define NLM_lock_sz 3+NLM_caller_sz+NLM_owner_sz+NLM_fhandle_sz
+#define NLM_holder_sz 4+NLM_owner_sz
#define NLM_testargs_sz NLM_cookie_sz+1+NLM_lock_sz
#define NLM_lockargs_sz NLM_cookie_sz+4+NLM_lock_sz
diff --git a/fs/lockd/xdr4.c b/fs/lockd/xdr4.c
index a782405..7c8b679 100644
--- a/fs/lockd/xdr4.c
+++ b/fs/lockd/xdr4.c
@@ -516,17 +516,24 @@
return 0;
}
+#if (NLMCLNT_OHSIZE > XDR_MAX_NETOBJ)
+# error "NLM host name cannot be larger than XDR_MAX_NETOBJ!"
+#endif
+
+#if (NLMCLNT_OHSIZE > NLM_MAXSTRLEN)
+# error "NLM host name cannot be larger than NLM's maximum string length!"
+#endif
+
/*
* Buffer requirements for NLM
*/
#define NLM4_void_sz 0
#define NLM4_cookie_sz 1+XDR_QUADLEN(NLM_MAXCOOKIELEN)
-#define NLM4_caller_sz 1+XDR_QUADLEN(NLM_MAXSTRLEN)
-#define NLM4_netobj_sz 1+XDR_QUADLEN(XDR_MAX_NETOBJ)
-/* #define NLM4_owner_sz 1+XDR_QUADLEN(NLM4_MAXOWNER) */
+#define NLM4_caller_sz 1+XDR_QUADLEN(NLMCLNT_OHSIZE)
+#define NLM4_owner_sz 1+XDR_QUADLEN(NLMCLNT_OHSIZE)
#define NLM4_fhandle_sz 1+XDR_QUADLEN(NFS3_FHSIZE)
-#define NLM4_lock_sz 5+NLM4_caller_sz+NLM4_netobj_sz+NLM4_fhandle_sz
-#define NLM4_holder_sz 6+NLM4_netobj_sz
+#define NLM4_lock_sz 5+NLM4_caller_sz+NLM4_owner_sz+NLM4_fhandle_sz
+#define NLM4_holder_sz 6+NLM4_owner_sz
#define NLM4_testargs_sz NLM4_cookie_sz+1+NLM4_lock_sz
#define NLM4_lockargs_sz NLM4_cookie_sz+4+NLM4_lock_sz
diff --git a/include/linux/lockd/lockd.h b/include/linux/lockd/lockd.h
index ac25b56..f6a81e0 100644
--- a/include/linux/lockd/lockd.h
+++ b/include/linux/lockd/lockd.h
@@ -88,7 +88,7 @@
/*
* Memory chunk for NLM client RPC request.
*/
-#define NLMCLNT_OHSIZE (sizeof(utsname()->nodename)+10)
+#define NLMCLNT_OHSIZE ((__NEW_UTS_LEN) + 10u)
struct nlm_rqst {
unsigned int a_flags; /* initial RPC task flags */
struct nlm_host * a_host; /* host handle */