nfsd-6.7 fixes:

- Fix several long-standing bugs in the duplicate reply cache
 - Fix a memory leak
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Merge tag 'nfsd-6.7-1' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux

Pull nfsd fixes from Chuck Lever:

 - Fix several long-standing bugs in the duplicate reply cache

 - Fix a memory leak

* tag 'nfsd-6.7-1' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux:
  NFSD: Fix checksum mismatches in the duplicate reply cache
  NFSD: Fix "start of NFS reply" pointer passed to nfsd_cache_update()
  NFSD: Update nfsd_cache_append() to use xdr_stream
  nfsd: fix file memleak on client_opens_release

fs/nfsd/cache.h

@@ -84,8 +84,8 @@ int	nfsd_net_reply_cache_init(struct nfsd_net *nn);
 void	nfsd_net_reply_cache_destroy(struct nfsd_net *nn);
 int	nfsd_reply_cache_init(struct nfsd_net *);
 void	nfsd_reply_cache_shutdown(struct nfsd_net *);
-int	nfsd_cache_lookup(struct svc_rqst *rqstp,
+int	nfsd_cache_lookup(struct svc_rqst *rqstp, unsigned int start,
-			  struct nfsd_cacherep **cacherep);
+			  unsigned int len, struct nfsd_cacherep **cacherep);
 void	nfsd_cache_update(struct svc_rqst *rqstp, struct nfsd_cacherep *rp,
 			  int cachetype, __be32 *statp);
 int	nfsd_reply_cache_stats_show(struct seq_file *m, void *v);

fs/nfsd/nfs4state.c

@@ -2804,7 +2804,7 @@ static int client_opens_release(struct inode *inode, struct file *file)
 
 	/* XXX: alternatively, we could get/drop in seq start/stop */
 	drop_client(clp);
-	return 0;
+	return seq_release(inode, file);
 }
 
 static const struct file_operations client_states_fops = {

fs/nfsd/nfscache.c

@@ -369,33 +369,52 @@ nfsd_reply_cache_scan(struct shrinker *shrink, struct shrink_control *sc)
 	return freed;
 }
 
-/*
+/**
- * Walk an xdr_buf and get a CRC for at most the first RC_CSUMLEN bytes
+ * nfsd_cache_csum - Checksum incoming NFS Call arguments
+ * @buf: buffer containing a whole RPC Call message
+ * @start: starting byte of the NFS Call header
+ * @remaining: size of the NFS Call header, in bytes
+ *
+ * Compute a weak checksum of the leading bytes of an NFS procedure
+ * call header to help verify that a retransmitted Call matches an
+ * entry in the duplicate reply cache.
+ *
+ * To avoid assumptions about how the RPC message is laid out in
+ * @buf and what else it might contain (eg, a GSS MIC suffix), the
+ * caller passes us the exact location and length of the NFS Call
+ * header.
+ *
+ * Returns a 32-bit checksum value, as defined in RFC 793.
  */
-static __wsum
+static __wsum nfsd_cache_csum(struct xdr_buf *buf, unsigned int start,
-nfsd_cache_csum(struct svc_rqst *rqstp)
+			      unsigned int remaining)
 {
+	unsigned int base, len;
+	struct xdr_buf subbuf;
+	__wsum csum = 0;
+	void *p;
 	int idx;
-	unsigned int base;
+
-	__wsum csum;
+	if (remaining > RC_CSUMLEN)
-	struct xdr_buf *buf = &rqstp->rq_arg;
+		remaining = RC_CSUMLEN;
-	const unsigned char *p = buf->head[0].iov_base;
+	if (xdr_buf_subsegment(buf, &subbuf, start, remaining))
-	size_t csum_len = min_t(size_t, buf->head[0].iov_len + buf->page_len,
+		return csum;
-				RC_CSUMLEN);
-	size_t len = min(buf->head[0].iov_len, csum_len);
 
 	/* rq_arg.head first */
-	csum = csum_partial(p, len, 0);
+	if (subbuf.head[0].iov_len) {
-	csum_len -= len;
+		len = min_t(unsigned int, subbuf.head[0].iov_len, remaining);
+		csum = csum_partial(subbuf.head[0].iov_base, len, csum);
+		remaining -= len;
+	}
 
 	/* Continue into page array */
-	idx = buf->page_base / PAGE_SIZE;
+	idx = subbuf.page_base / PAGE_SIZE;
-	base = buf->page_base & ~PAGE_MASK;
+	base = subbuf.page_base & ~PAGE_MASK;
-	while (csum_len) {
+	while (remaining) {
-		p = page_address(buf->pages[idx]) + base;
+		p = page_address(subbuf.pages[idx]) + base;
-		len = min_t(size_t, PAGE_SIZE - base, csum_len);
+		len = min_t(unsigned int, PAGE_SIZE - base, remaining);
 		csum = csum_partial(p, len, csum);
-		csum_len -= len;
+		remaining -= len;
 		base = 0;
 		++idx;
 	}
@@ -466,6 +485,8 @@ out:
 /**
  * nfsd_cache_lookup - Find an entry in the duplicate reply cache
  * @rqstp: Incoming Call to find
+ * @start: starting byte in @rqstp->rq_arg of the NFS Call header
+ * @len: size of the NFS Call header, in bytes
  * @cacherep: OUT: DRC entry for this request
  *
  * Try to find an entry matching the current call in the cache. When none
@@ -479,7 +500,8 @@ out:
  *   %RC_REPLY: Reply from cache
  *   %RC_DROPIT: Do not process the request further
  */
-int nfsd_cache_lookup(struct svc_rqst *rqstp, struct nfsd_cacherep **cacherep)
+int nfsd_cache_lookup(struct svc_rqst *rqstp, unsigned int start,
+		      unsigned int len, struct nfsd_cacherep **cacherep)
 {
 	struct nfsd_net		*nn;
 	struct nfsd_cacherep	*rp, *found;
@@ -495,7 +517,7 @@ int nfsd_cache_lookup(struct svc_rqst *rqstp, struct nfsd_cacherep **cacherep)
 		goto out;
 	}
 
-	csum = nfsd_cache_csum(rqstp);
+	csum = nfsd_cache_csum(&rqstp->rq_arg, start, len);
 
 	/*
 	 * Since the common case is a cache miss followed by an insert,
@@ -641,24 +663,17 @@ void nfsd_cache_update(struct svc_rqst *rqstp, struct nfsd_cacherep *rp,
 	return;
 }
 
-/*
- * Copy cached reply to current reply buffer. Should always fit.
- * FIXME as reply is in a page, we should just attach the page, and
- * keep a refcount....
- */
 static int
 nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *data)
 {
-	struct kvec	*vec = &rqstp->rq_res.head[0];
+	__be32 *p;
 
-	if (vec->iov_len + data->iov_len > PAGE_SIZE) {
+	p = xdr_reserve_space(&rqstp->rq_res_stream, data->iov_len);
-		printk(KERN_WARNING "nfsd: cached reply too large (%zd).\n",
+	if (unlikely(!p))
-				data->iov_len);
+		return false;
-		return 0;
+	memcpy(p, data->iov_base, data->iov_len);
-	}
+	xdr_commit_encode(&rqstp->rq_res_stream);
-	memcpy((char*)vec->iov_base + vec->iov_len, data->iov_base, data->iov_len);
+	return true;
-	vec->iov_len += data->iov_len;
-	return 1;
 }
 
 /*

fs/nfsd/nfssvc.c

@@ -981,6 +981,8 @@ int nfsd_dispatch(struct svc_rqst *rqstp)
 	const struct svc_procedure *proc = rqstp->rq_procinfo;
 	__be32 *statp = rqstp->rq_accept_statp;
 	struct nfsd_cacherep *rp;
+	unsigned int start, len;
+	__be32 *nfs_reply;
 
 	/*
 	 * Give the xdr decoder a chance to change this if it wants
@@ -988,6 +990,13 @@ int nfsd_dispatch(struct svc_rqst *rqstp)
 	 */
 	rqstp->rq_cachetype = proc->pc_cachetype;
 
+	/*
+	 * ->pc_decode advances the argument stream past the NFS
+	 * Call header, so grab the header's starting location and
+	 * size now for the call to nfsd_cache_lookup().
+	 */
+	start = xdr_stream_pos(&rqstp->rq_arg_stream);
+	len = xdr_stream_remaining(&rqstp->rq_arg_stream);
 	if (!proc->pc_decode(rqstp, &rqstp->rq_arg_stream))
 		goto out_decode_err;
 
@@ -1001,7 +1010,7 @@ int nfsd_dispatch(struct svc_rqst *rqstp)
 	smp_store_release(&rqstp->rq_status_counter, rqstp->rq_status_counter | 1);
 
 	rp = NULL;
-	switch (nfsd_cache_lookup(rqstp, &rp)) {
+	switch (nfsd_cache_lookup(rqstp, start, len, &rp)) {
 	case RC_DOIT:
 		break;
 	case RC_REPLY:
@@ -1010,6 +1019,7 @@ int nfsd_dispatch(struct svc_rqst *rqstp)
 		goto out_dropit;
 	}
 
+	nfs_reply = xdr_inline_decode(&rqstp->rq_res_stream, 0);
 	*statp = proc->pc_func(rqstp);
 	if (test_bit(RQ_DROPME, &rqstp->rq_flags))
 		goto out_update_drop;
@@ -1023,7 +1033,7 @@ int nfsd_dispatch(struct svc_rqst *rqstp)
 	 */
 	smp_store_release(&rqstp->rq_status_counter, rqstp->rq_status_counter + 1);
 
-	nfsd_cache_update(rqstp, rp, rqstp->rq_cachetype, statp + 1);
+	nfsd_cache_update(rqstp, rp, rqstp->rq_cachetype, nfs_reply);
 out_cached_reply:
 	return 1;