lockd: Introduce new-style XDR functions for NLMv3

We'd like to prevent local buffer overflows caused by malicious or
broken servers.  New xdr_stream style decoders can do that.

For efficiency, we also eventually want to be able to pass xdr_streams
from call_encode() and call_decode() to all XDR encoding functions,
rather than building an xdr_stream in every XDR encoding and decoding
function in the kernel.

To do all of this, rewrite the XDR encoding and decoding functions in
fs/lockd/xdr.c to use xdr_streams.  This makes them more or less
incompatible with server-side XDR helper functions, so break them out
into a separate source file.

Static helper functions are left without the "inline" directive.  This
allows the compiler to choose automatically how to optimize these for
size or speed.

SHARE-related functionality doesn't seem to be used, as those
functions are hiding behind a #define that isn't set anywhere that I
can find.  And, they've been in there forever (at least as far back as
the kernel's git history goes), yet remain unused.  Let's take the
opportunity to bin them.  It should be easy enough for someone to
introduce proper XDR functions if at some point SHARE-related NLM
functionality is desired.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/lockd/Makefile

@@ -4,7 +4,7 @@
 
 obj-$(CONFIG_LOCKD) += lockd.o
 
-lockd-objs-y := clntlock.o clntproc.o host.o svc.o svclock.o svcshare.o \
-	        svcproc.o svcsubs.o mon.o xdr.o grace.o
+lockd-objs-y := clntlock.o clntproc.o clntxdr.o host.o svc.o svclock.o \
+	        svcshare.o svcproc.o svcsubs.o mon.o xdr.o grace.o
 lockd-objs-$(CONFIG_LOCKD_V4) += xdr4.o svc4proc.o
 lockd-objs		      := $(lockd-objs-y)

fs/lockd/xdr.c

@@ -148,37 +148,6 @@ nlm_decode_lock(__be32 *p, struct nlm_lock *lock)
 	return p;
 }
 
-/*
- * Encode a lock as part of an NLM call
- */
-static __be32 *
-nlm_encode_lock(__be32 *p, struct nlm_lock *lock)
-{
-	struct file_lock	*fl = &lock->fl;
-	__s32			start, len;
-
-	if (!(p = xdr_encode_string(p, lock->caller))
-	 || !(p = nlm_encode_fh(p, &lock->fh))
-	 || !(p = nlm_encode_oh(p, &lock->oh)))
-		return NULL;
-
-	if (fl->fl_start > NLM_OFFSET_MAX
-	 || (fl->fl_end > NLM_OFFSET_MAX && fl->fl_end != OFFSET_MAX))
-		return NULL;
-
-	start = loff_t_to_s32(fl->fl_start);
-	if (fl->fl_end == OFFSET_MAX)
-		len = 0;
-	else
-		len = loff_t_to_s32(fl->fl_end - fl->fl_start + 1);
-
-	*p++ = htonl(lock->svid);
-	*p++ = htonl(start);
-	*p++ = htonl(len);
-
-	return p;
-}
-
 /*
  * Encode result of a TEST/TEST_MSG call
  */
@@ -373,233 +342,6 @@ nlmsvc_encode_void(struct svc_rqst *rqstp, __be32 *p, void *dummy)
 	return xdr_ressize_check(rqstp, p);
 }
 
-/*
- * Now, the client side XDR functions
- */
-#ifdef NLMCLNT_SUPPORT_SHARES
-static int
-nlmclt_decode_void(struct rpc_rqst *req, u32 *p, void *ptr)
-{
-	return 0;
-}
-#endif
-
-static int
-nlmclt_encode_testargs(struct rpc_rqst *req, __be32 *p, nlm_args *argp)
-{
-	struct nlm_lock	*lock = &argp->lock;
-
-	if (!(p = nlm_encode_cookie(p, &argp->cookie)))
-		return -EIO;
-	*p++ = (lock->fl.fl_type == F_WRLCK)? xdr_one : xdr_zero;
-	if (!(p = nlm_encode_lock(p, lock)))
-		return -EIO;
-	req->rq_slen = xdr_adjust_iovec(req->rq_svec, p);
-	return 0;
-}
-
-static int
-nlmclt_decode_testres(struct rpc_rqst *req, __be32 *p, struct nlm_res *resp)
-{
-	if (!(p = nlm_decode_cookie(p, &resp->cookie)))
-		return -EIO;
-	resp->status = *p++;
-	if (resp->status == nlm_lck_denied) {
-		struct file_lock	*fl = &resp->lock.fl;
-		u32			excl;
-		s32			start, len, end;
-
-		memset(&resp->lock, 0, sizeof(resp->lock));
-		locks_init_lock(fl);
-		excl = ntohl(*p++);
-		resp->lock.svid = ntohl(*p++);
-		fl->fl_pid = (pid_t)resp->lock.svid;
-		if (!(p = nlm_decode_oh(p, &resp->lock.oh)))
-			return -EIO;
-
-		fl->fl_flags = FL_POSIX;
-		fl->fl_type  = excl? F_WRLCK : F_RDLCK;
-		start = ntohl(*p++);
-		len = ntohl(*p++);
-		end = start + len - 1;
-
-		fl->fl_start = s32_to_loff_t(start);
-		if (len == 0 || end < 0)
-			fl->fl_end = OFFSET_MAX;
-		else
-			fl->fl_end = s32_to_loff_t(end);
-	}
-	return 0;
-}
-
-
-static int
-nlmclt_encode_lockargs(struct rpc_rqst *req, __be32 *p, nlm_args *argp)
-{
-	struct nlm_lock	*lock = &argp->lock;
-
-	if (!(p = nlm_encode_cookie(p, &argp->cookie)))
-		return -EIO;
-	*p++ = argp->block? xdr_one : xdr_zero;
-	*p++ = (lock->fl.fl_type == F_WRLCK)? xdr_one : xdr_zero;
-	if (!(p = nlm_encode_lock(p, lock)))
-		return -EIO;
-	*p++ = argp->reclaim? xdr_one : xdr_zero;
-	*p++ = htonl(argp->state);
-	req->rq_slen = xdr_adjust_iovec(req->rq_svec, p);
-	return 0;
-}
-
-static int
-nlmclt_encode_cancargs(struct rpc_rqst *req, __be32 *p, nlm_args *argp)
-{
-	struct nlm_lock	*lock = &argp->lock;
-
-	if (!(p = nlm_encode_cookie(p, &argp->cookie)))
-		return -EIO;
-	*p++ = argp->block? xdr_one : xdr_zero;
-	*p++ = (lock->fl.fl_type == F_WRLCK)? xdr_one : xdr_zero;
-	if (!(p = nlm_encode_lock(p, lock)))
-		return -EIO;
-	req->rq_slen = xdr_adjust_iovec(req->rq_svec, p);
-	return 0;
-}
-
-static int
-nlmclt_encode_unlockargs(struct rpc_rqst *req, __be32 *p, nlm_args *argp)
-{
-	struct nlm_lock	*lock = &argp->lock;
-
-	if (!(p = nlm_encode_cookie(p, &argp->cookie)))
-		return -EIO;
-	if (!(p = nlm_encode_lock(p, lock)))
-		return -EIO;
-	req->rq_slen = xdr_adjust_iovec(req->rq_svec, p);
-	return 0;
-}
-
-static int
-nlmclt_encode_res(struct rpc_rqst *req, __be32 *p, struct nlm_res *resp)
-{
-	if (!(p = nlm_encode_cookie(p, &resp->cookie)))
-		return -EIO;
-	*p++ = resp->status;
-	req->rq_slen = xdr_adjust_iovec(req->rq_svec, p);
-	return 0;
-}
-
-static int
-nlmclt_encode_testres(struct rpc_rqst *req, __be32 *p, struct nlm_res *resp)
-{
-	if (!(p = nlm_encode_testres(p, resp)))
-		return -EIO;
-	req->rq_slen = xdr_adjust_iovec(req->rq_svec, p);
-	return 0;
-}
-
-static int
-nlmclt_decode_res(struct rpc_rqst *req, __be32 *p, struct nlm_res *resp)
-{
-	if (!(p = nlm_decode_cookie(p, &resp->cookie)))
-		return -EIO;
-	resp->status = *p++;
-	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(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_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
-#define NLM_cancargs_sz		NLM_cookie_sz+2+NLM_lock_sz
-#define NLM_unlockargs_sz	NLM_cookie_sz+NLM_lock_sz
-
-#define NLM_testres_sz		NLM_cookie_sz+1+NLM_holder_sz
-#define NLM_res_sz		NLM_cookie_sz+1
-#define NLM_norep_sz		0
-
-/*
- * For NLM, a void procedure really returns nothing
- */
-#define nlmclt_decode_norep	NULL
-
-#define PROC(proc, argtype, restype)	\
-[NLMPROC_##proc] = {							\
-	.p_proc      = NLMPROC_##proc,					\
-	.p_encode    = (kxdrproc_t) nlmclt_encode_##argtype,		\
-	.p_decode    = (kxdrproc_t) nlmclt_decode_##restype,		\
-	.p_arglen    = NLM_##argtype##_sz,				\
-	.p_replen    = NLM_##restype##_sz,				\
-	.p_statidx   = NLMPROC_##proc,					\
-	.p_name      = #proc,						\
-	}
-
-static struct rpc_procinfo	nlm_procedures[] = {
-    PROC(TEST,		testargs,	testres),
-    PROC(LOCK,		lockargs,	res),
-    PROC(CANCEL,	cancargs,	res),
-    PROC(UNLOCK,	unlockargs,	res),
-    PROC(GRANTED,	testargs,	res),
-    PROC(TEST_MSG,	testargs,	norep),
-    PROC(LOCK_MSG,	lockargs,	norep),
-    PROC(CANCEL_MSG,	cancargs,	norep),
-    PROC(UNLOCK_MSG,	unlockargs,	norep),
-    PROC(GRANTED_MSG,	testargs,	norep),
-    PROC(TEST_RES,	testres,	norep),
-    PROC(LOCK_RES,	res,		norep),
-    PROC(CANCEL_RES,	res,		norep),
-    PROC(UNLOCK_RES,	res,		norep),
-    PROC(GRANTED_RES,	res,		norep),
-#ifdef NLMCLNT_SUPPORT_SHARES
-    PROC(SHARE,		shareargs,	shareres),
-    PROC(UNSHARE,	shareargs,	shareres),
-    PROC(NM_LOCK,	lockargs,	res),
-    PROC(FREE_ALL,	notify,		void),
-#endif
-};
-
-static struct rpc_version	nlm_version1 = {
-		.number		= 1,
-		.nrprocs	= 16,
-		.procs		= nlm_procedures,
-};
-
-static struct rpc_version	nlm_version3 = {
-		.number		= 3,
-		.nrprocs	= 24,
-		.procs		= nlm_procedures,
-};
-
-static struct rpc_version *	nlm_versions[] = {
-	[1] = &nlm_version1,
-	[3] = &nlm_version3,
-#ifdef 	CONFIG_LOCKD_V4
-	[4] = &nlm_version4,
-#endif
-};
-
-static struct rpc_stat		nlm_stats;
-
-struct rpc_program		nlm_program = {
-		.name		= "lockd",
-		.number		= NLM_PROGRAM,
-		.nrvers		= ARRAY_SIZE(nlm_versions),
-		.version	= nlm_versions,
-		.stats		= &nlm_stats,
-};
-
 #ifdef RPC_DEBUG
 const char *nlmdbg_cookie2a(const struct nlm_cookie *cookie)
 {