lockd: Introduce new-style XDR functions for NLMv4

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 want to be able to pass xdr_streams from
call_encode() to all XDR encoding functions, rather than building
an xdr_stream in every XDR encoding function in the kernel.

Same idea as the NLM v3 XDR overhaul.

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>

1 files changed, 621 insertions, 0 deletions

diff --git a/fs/lockd/clnt4xdr.c b/fs/lockd/clnt4xdr.c
new file mode 100644
index 000000000000..1a1c3e21ed2c
--- /dev/null
+++ b/fs/lockd/clnt4xdr.c
@@ -0,0 +1,621 @@
+/*
+ * linux/fs/lockd/clnt4xdr.c
+ *
+ * XDR functions to encode/decode NLM version 4 RPC arguments and results.
+ *
+ * NLM client-side only.
+ *
+ * Copyright (C) 2010, Oracle.  All rights reserved.
+ */
+
+#include <linux/types.h>
+#include <linux/sunrpc/xdr.h>
+#include <linux/sunrpc/clnt.h>
+#include <linux/sunrpc/stats.h>
+#include <linux/lockd/lockd.h>
+
+#define NLMDBG_FACILITY		NLMDBG_XDR
+
+#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
+
+/*
+ * Declare the space requirements for NLM arguments and replies as
+ * number of 32bit-words
+ */
+#define NLM4_void_sz		(0)
+#define NLM4_cookie_sz		(1+(NLM_MAXCOOKIELEN>>2))
+#define NLM4_caller_sz		(1+(NLMCLNT_OHSIZE>>2))
+#define NLM4_owner_sz		(1+(NLMCLNT_OHSIZE>>2))
+#define NLM4_fhandle_sz		(1+(NFS3_FHSIZE>>2))
+#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)
+#define NLM4_cancargs_sz	(NLM4_cookie_sz+2+NLM4_lock_sz)
+#define NLM4_unlockargs_sz	(NLM4_cookie_sz+NLM4_lock_sz)
+
+#define NLM4_testres_sz		(NLM4_cookie_sz+1+NLM4_holder_sz)
+#define NLM4_res_sz		(NLM4_cookie_sz+1)
+#define NLM4_norep_sz		(0)
+
+
+static s64 loff_t_to_s64(loff_t offset)
+{
+	s64 res;
+
+	if (offset >= NLM4_OFFSET_MAX)
+		res = NLM4_OFFSET_MAX;
+	else if (offset <= -NLM4_OFFSET_MAX)
+		res = -NLM4_OFFSET_MAX;
+	else
+		res = offset;
+	return res;
+}
+
+static void nlm4_compute_offsets(const struct nlm_lock *lock,
+				 u64 *l_offset, u64 *l_len)
+{
+	const struct file_lock *fl = &lock->fl;
+
+	BUG_ON(fl->fl_start > NLM4_OFFSET_MAX);
+	BUG_ON(fl->fl_end > NLM4_OFFSET_MAX &&
+				fl->fl_end != OFFSET_MAX);
+
+	*l_offset = loff_t_to_s64(fl->fl_start);
+	if (fl->fl_end == OFFSET_MAX)
+		*l_len = 0;
+	else
+		*l_len = loff_t_to_s64(fl->fl_end - fl->fl_start + 1);
+}
+
+/*
+ * Handle decode buffer overflows out-of-line.
+ */
+static void print_overflow_msg(const char *func, const struct xdr_stream *xdr)
+{
+	dprintk("lockd: %s prematurely hit the end of our receive buffer. "
+		"Remaining buffer length is %tu words.\n",
+		func, xdr->end - xdr->p);
+}
+
+
+/*
+ * Encode/decode NLMv4 basic data types
+ *
+ * Basic NLMv4 data types are defined in Appendix II, section 6.1.4
+ * of RFC 1813: "NFS Version 3 Protocol Specification" and in Chapter
+ * 10 of X/Open's "Protocols for Interworking: XNFS, Version 3W".
+ *
+ * Not all basic data types have their own encoding and decoding
+ * functions.  For run-time efficiency, some data types are encoded
+ * or decoded inline.
+ */
+
+static void encode_bool(struct xdr_stream *xdr, const int value)
+{
+	__be32 *p;
+
+	p = xdr_reserve_space(xdr, 4);
+	*p = value ? xdr_one : xdr_zero;
+}
+
+static void encode_int32(struct xdr_stream *xdr, const s32 value)
+{
+	__be32 *p;
+
+	p = xdr_reserve_space(xdr, 4);
+	*p = cpu_to_be32(value);
+}
+
+/*
+ *	typedef opaque netobj<MAXNETOBJ_SZ>
+ */
+static void encode_netobj(struct xdr_stream *xdr,
+			  const u8 *data, const unsigned int length)
+{
+	__be32 *p;
+
+	BUG_ON(length > XDR_MAX_NETOBJ);
+	p = xdr_reserve_space(xdr, 4 + length);
+	xdr_encode_opaque(p, data, length);
+}
+
+static int decode_netobj(struct xdr_stream *xdr,
+			 struct xdr_netobj *obj)
+{
+	u32 length;
+	__be32 *p;
+
+	p = xdr_inline_decode(xdr, 4);
+	if (unlikely(p == NULL))
+		goto out_overflow;
+	length = be32_to_cpup(p++);
+	if (unlikely(length > XDR_MAX_NETOBJ))
+		goto out_size;
+	obj->len = length;
+	obj->data = (u8 *)p;
+	return 0;
+out_size:
+	dprintk("NFS: returned netobj was too long: %u\n", length);
+	return -EIO;
+out_overflow:
+	print_overflow_msg(__func__, xdr);
+	return -EIO;
+}
+
+/*
+ *	netobj cookie;
+ */
+static void encode_cookie(struct xdr_stream *xdr,
+			  const struct nlm_cookie *cookie)
+{
+	BUG_ON(cookie->len > NLM_MAXCOOKIELEN);
+	encode_netobj(xdr, (u8 *)&cookie->data, cookie->len);
+}
+
+static int decode_cookie(struct xdr_stream *xdr,
+			     struct nlm_cookie *cookie)
+{
+	u32 length;
+	__be32 *p;
+
+	p = xdr_inline_decode(xdr, 4);
+	if (unlikely(p == NULL))
+		goto out_overflow;
+	length = be32_to_cpup(p++);
+	/* apparently HPUX can return empty cookies */
+	if (length == 0)
+		goto out_hpux;
+	if (length > NLM_MAXCOOKIELEN)
+		goto out_size;
+	p = xdr_inline_decode(xdr, length);
+	if (unlikely(p == NULL))
+		goto out_overflow;
+	cookie->len = length;
+	memcpy(cookie->data, p, length);
+	return 0;
+out_hpux:
+	cookie->len = 4;
+	memset(cookie->data, 0, 4);
+	return 0;
+out_size:
+	dprintk("NFS: returned cookie was too long: %u\n", length);
+	return -EIO;
+out_overflow:
+	print_overflow_msg(__func__, xdr);
+	return -EIO;
+}
+
+/*
+ *	netobj fh;
+ */
+static void encode_fh(struct xdr_stream *xdr, const struct nfs_fh *fh)
+{
+	BUG_ON(fh->size > NFS3_FHSIZE);
+	encode_netobj(xdr, (u8 *)&fh->data, fh->size);
+}
+
+/*
+ *	enum nlm4_stats {
+ *		NLM4_GRANTED = 0,
+ *		NLM4_DENIED = 1,
+ *		NLM4_DENIED_NOLOCKS = 2,
+ *		NLM4_BLOCKED = 3,
+ *		NLM4_DENIED_GRACE_PERIOD = 4,
+ *		NLM4_DEADLCK = 5,
+ *		NLM4_ROFS = 6,
+ *		NLM4_STALE_FH = 7,
+ *		NLM4_FBIG = 8,
+ *		NLM4_FAILED = 9
+ *	};
+ *
+ *	struct nlm4_stat {
+ *		nlm4_stats stat;
+ *	};
+ *
+ * NB: we don't swap bytes for the NLM status values.  The upper
+ * layers deal directly with the status value in network byte
+ * order.
+ */
+static void encode_nlm4_stat(struct xdr_stream *xdr,
+			     const __be32 stat)
+{
+	__be32 *p;
+
+	BUG_ON(be32_to_cpu(stat) > NLM_FAILED);
+	p = xdr_reserve_space(xdr, 4);
+	*p = stat;
+}
+
+static int decode_nlm4_stat(struct xdr_stream *xdr, __be32 *stat)
+{
+	__be32 *p;
+
+	p = xdr_inline_decode(xdr, 4);
+	if (unlikely(p == NULL))
+		goto out_overflow;
+	if (unlikely(*p > nlm4_failed))
+		goto out_bad_xdr;
+	*stat = *p;
+	return 0;
+out_bad_xdr:
+	dprintk("%s: server returned invalid nlm4_stats value: %u\n",
+			__func__, be32_to_cpup(p));
+	return -EIO;
+out_overflow:
+	print_overflow_msg(__func__, xdr);
+	return -EIO;
+}
+
+/*
+ *	struct nlm4_holder {
+ *		bool	exclusive;
+ *		int32	svid;
+ *		netobj	oh;
+ *		uint64	l_offset;
+ *		uint64	l_len;
+ *	};
+ */
+static void encode_nlm4_holder(struct xdr_stream *xdr,
+			       const struct nlm_res *result)
+{
+	const struct nlm_lock *lock = &result->lock;
+	u64 l_offset, l_len;
+	__be32 *p;
+
+	encode_bool(xdr, lock->fl.fl_type == F_RDLCK);
+	encode_int32(xdr, lock->svid);
+	encode_netobj(xdr, lock->oh.data, lock->oh.len);
+
+	p = xdr_reserve_space(xdr, 4 + 4);
+	nlm4_compute_offsets(lock, &l_offset, &l_len);
+	p = xdr_encode_hyper(p, l_offset);
+	xdr_encode_hyper(p, l_len);
+}
+
+static int decode_nlm4_holder(struct xdr_stream *xdr, struct nlm_res *result)
+{
+	struct nlm_lock *lock = &result->lock;
+	struct file_lock *fl = &lock->fl;
+	u64 l_offset, l_len;
+	u32 exclusive;
+	int error;
+	__be32 *p;
+	s32 end;
+
+	memset(lock, 0, sizeof(*lock));
+	locks_init_lock(fl);
+
+	p = xdr_inline_decode(xdr, 4 + 4);
+	if (unlikely(p == NULL))
+		goto out_overflow;
+	exclusive = be32_to_cpup(p++);
+	lock->svid = be32_to_cpup(p);
+	fl->fl_pid = (pid_t)lock->svid;
+
+	error = decode_netobj(xdr, &lock->oh);
+	if (unlikely(error))
+		goto out;
+
+	p = xdr_inline_decode(xdr, 8 + 8);
+	if (unlikely(p == NULL))
+		goto out_overflow;
+
+	fl->fl_flags = FL_POSIX;
+	fl->fl_type  = exclusive != 0 ? F_WRLCK : F_RDLCK;
+	p = xdr_decode_hyper(p, &l_offset);
+	xdr_decode_hyper(p, &l_len);
+	end = l_offset + l_len - 1;
+
+	fl->fl_start = (loff_t)l_offset;
+	if (l_len == 0 || end < 0)
+		fl->fl_end = OFFSET_MAX;
+	else
+		fl->fl_end = (loff_t)end;
+	error = 0;
+out:
+	return error;
+out_overflow:
+	print_overflow_msg(__func__, xdr);
+	return -EIO;
+}
+
+/*
+ *	string caller_name<LM_MAXSTRLEN>;
+ */
+static void encode_caller_name(struct xdr_stream *xdr, const char *name)
+{
+	/* NB: client-side does not set lock->len */
+	u32 length = strlen(name);
+	__be32 *p;
+
+	BUG_ON(length > NLM_MAXSTRLEN);
+	p = xdr_reserve_space(xdr, 4 + length);
+	xdr_encode_opaque(p, name, length);
+}
+
+/*
+ *	struct nlm4_lock {
+ *		string	caller_name<LM_MAXSTRLEN>;
+ *		netobj	fh;
+ *		netobj	oh;
+ *		int32	svid;
+ *		uint64	l_offset;
+ *		uint64	l_len;
+ *	};
+ */
+static void encode_nlm4_lock(struct xdr_stream *xdr,
+			     const struct nlm_lock *lock)
+{
+	u64 l_offset, l_len;
+	__be32 *p;
+
+	encode_caller_name(xdr, lock->caller);
+	encode_fh(xdr, &lock->fh);
+	encode_netobj(xdr, lock->oh.data, lock->oh.len);
+
+	p = xdr_reserve_space(xdr, 4 + 8 + 8);
+	*p++ = cpu_to_be32(lock->svid);
+
+	nlm4_compute_offsets(lock, &l_offset, &l_len);
+	p = xdr_encode_hyper(p, l_offset);
+	xdr_encode_hyper(p, l_len);
+}
+
+
+/*
+ * NLMv4 XDR encode functions
+ *
+ * NLMv4 argument types are defined in Appendix II of RFC 1813:
+ * "NFS Version 3 Protocol Specification" and Chapter 10 of X/Open's
+ * "Protocols for Interworking: XNFS, Version 3W".
+ */
+
+/*
+ *	struct nlm4_testargs {
+ *		netobj cookie;
+ *		bool exclusive;
+ *		struct nlm4_lock alock;
+ *	};
+ */
+static int nlm4_xdr_enc_testargs(struct rpc_rqst *req, __be32 *p,
+				 const struct nlm_args *args)
+{
+	const struct nlm_lock *lock = &args->lock;
+	struct xdr_stream xdr;
+
+	xdr_init_encode(&xdr, &req->rq_snd_buf, p);
+	encode_cookie(&xdr, &args->cookie);
+	encode_bool(&xdr, lock->fl.fl_type == F_WRLCK);
+	encode_nlm4_lock(&xdr, lock);
+	return 0;
+}
+
+/*
+ *	struct nlm4_lockargs {
+ *		netobj cookie;
+ *		bool block;
+ *		bool exclusive;
+ *		struct nlm4_lock alock;
+ *		bool reclaim;
+ *		int state;
+ *	};
+ */
+static int nlm4_xdr_enc_lockargs(struct rpc_rqst *req, __be32 *p,
+				 const struct nlm_args *args)
+{
+	const struct nlm_lock *lock = &args->lock;
+	struct xdr_stream xdr;
+
+	xdr_init_encode(&xdr, &req->rq_snd_buf, p);
+	encode_cookie(&xdr, &args->cookie);
+	encode_bool(&xdr, args->block);
+	encode_bool(&xdr, lock->fl.fl_type == F_WRLCK);
+	encode_nlm4_lock(&xdr, lock);
+	encode_bool(&xdr, args->reclaim);
+	encode_int32(&xdr, args->state);
+	return 0;
+}
+
+/*
+ *	struct nlm4_cancargs {
+ *		netobj cookie;
+ *		bool block;
+ *		bool exclusive;
+ *		struct nlm4_lock alock;
+ *	};
+ */
+static int nlm4_xdr_enc_cancargs(struct rpc_rqst *req, __be32 *p,
+				 const struct nlm_args *args)
+{
+	const struct nlm_lock *lock = &args->lock;
+	struct xdr_stream xdr;
+
+	xdr_init_encode(&xdr, &req->rq_snd_buf, p);
+	encode_cookie(&xdr, &args->cookie);
+	encode_bool(&xdr, args->block);
+	encode_bool(&xdr, lock->fl.fl_type == F_WRLCK);
+	encode_nlm4_lock(&xdr, lock);
+	return 0;
+}
+
+/*
+ *	struct nlm4_unlockargs {
+ *		netobj cookie;
+ *		struct nlm4_lock alock;
+ *	};
+ */
+static int nlm4_xdr_enc_unlockargs(struct rpc_rqst *req, __be32 *p,
+				   const struct nlm_args *args)
+{
+	const struct nlm_lock *lock = &args->lock;
+	struct xdr_stream xdr;
+
+	xdr_init_encode(&xdr, &req->rq_snd_buf, p);
+	encode_cookie(&xdr, &args->cookie);
+	encode_nlm4_lock(&xdr, lock);
+	return 0;
+}
+
+/*
+ *	struct nlm4_res {
+ *		netobj cookie;
+ *		nlm4_stat stat;
+ *	};
+ */
+static int nlm4_xdr_enc_res(struct rpc_rqst *req, __be32 *p,
+			    const struct nlm_res *result)
+{
+	struct xdr_stream xdr;
+
+	xdr_init_encode(&xdr, &req->rq_snd_buf, p);
+	encode_cookie(&xdr, &result->cookie);
+	encode_nlm4_stat(&xdr, result->status);
+	return 0;
+}
+
+/*
+ *	union nlm4_testrply switch (nlm4_stats stat) {
+ *	case NLM4_DENIED:
+ *		struct nlm4_holder holder;
+ *	default:
+ *		void;
+ *	};
+ *
+ *	struct nlm4_testres {
+ *		netobj cookie;
+ *		nlm4_testrply test_stat;
+ *	};
+ */
+static int nlm4_xdr_enc_testres(struct rpc_rqst *req, __be32 *p,
+				const struct nlm_res *result)
+{
+	struct xdr_stream xdr;
+
+	xdr_init_encode(&xdr, &req->rq_snd_buf, p);
+	encode_cookie(&xdr, &result->cookie);
+	encode_nlm4_stat(&xdr, result->status);
+	if (result->status == nlm_lck_denied)
+		encode_nlm4_holder(&xdr, result);
+	return 0;
+}
+
+
+/*
+ * NLMv4 XDR decode functions
+ *
+ * NLMv4 argument types are defined in Appendix II of RFC 1813:
+ * "NFS Version 3 Protocol Specification" and Chapter 10 of X/Open's
+ * "Protocols for Interworking: XNFS, Version 3W".
+ */
+
+/*
+ *	union nlm4_testrply switch (nlm4_stats stat) {
+ *	case NLM4_DENIED:
+ *		struct nlm4_holder holder;
+ *	default:
+ *		void;
+ *	};
+ *
+ *	struct nlm4_testres {
+ *		netobj cookie;
+ *		nlm4_testrply test_stat;
+ *	};
+ */
+static int decode_nlm4_testrply(struct xdr_stream *xdr,
+				struct nlm_res *result)
+{
+	int error;
+
+	error = decode_nlm4_stat(xdr, &result->status);
+	if (unlikely(error))
+		goto out;
+	if (result->status == nlm_lck_denied)
+		error = decode_nlm4_holder(xdr, result);
+out:
+	return error;
+}
+
+static int nlm4_xdr_dec_testres(struct rpc_rqst *req, __be32 *p,
+				struct nlm_res *result)
+{
+	struct xdr_stream xdr;
+	int error;
+
+	xdr_init_decode(&xdr, &req->rq_rcv_buf, p);
+	error = decode_cookie(&xdr, &result->cookie);
+	if (unlikely(error))
+		goto out;
+	error = decode_nlm4_testrply(&xdr, result);
+out:
+	return error;
+}
+
+/*
+ *	struct nlm4_res {
+ *		netobj cookie;
+ *		nlm4_stat stat;
+ *	};
+ */
+static int nlm4_xdr_dec_res(struct rpc_rqst *req, __be32 *p,
+			    struct nlm_res *result)
+{
+	struct xdr_stream xdr;
+	int error;
+
+	xdr_init_decode(&xdr, &req->rq_rcv_buf, p);
+	error = decode_cookie(&xdr, &result->cookie);
+	if (unlikely(error))
+		goto out;
+	error = decode_nlm4_stat(&xdr, &result->status);
+out:
+	return error;
+}
+
+
+/*
+ * For NLM, a void procedure really returns nothing
+ */
+#define nlm4_xdr_dec_norep	NULL
+
+#define PROC(proc, argtype, restype)					\
+[NLMPROC_##proc] = {							\
+	.p_proc      = NLMPROC_##proc,					\
+	.p_encode    = (kxdrproc_t)nlm4_xdr_enc_##argtype,		\
+	.p_decode    = (kxdrproc_t)nlm4_xdr_dec_##restype,		\
+	.p_arglen    = NLM4_##argtype##_sz,				\
+	.p_replen    = NLM4_##restype##_sz,				\
+	.p_statidx   = NLMPROC_##proc,					\
+	.p_name      = #proc,						\
+	}
+
+static struct rpc_procinfo	nlm4_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),
+};
+
+struct rpc_version	nlm_version4 = {
+	.number		= 4,
+	.nrprocs	= ARRAY_SIZE(nlm4_procedures),
+	.procs		= nlm4_procedures,
+};