[PATCH] fs: nfs: copy data from rpc replies to local storage

* [PATCH] fs: nfs: copy data from rpc replies to local storage
@ 2019-01-15 10:53 Uwe Kleine-König
  2019-01-18 14:36 ` [PATCH v2] " Uwe Kleine-König
  0 siblings, 1 reply; 2+ messages in thread
From: Uwe Kleine-König @ 2019-01-15 10:53 UTC (permalink / raw)
  To: barebox

The nfs code uses data provided to the packet handler after net_poll()
returned. But the life time of this data already ended when net_poll()
returns. Most of the time it is possible to get away here but on i.MX28
the data is overwritten since commit 82ec28929cc9 ("net: fec_imx: Do not
use DMA coherent memory for Rx buffers").

So the data from the packet is copied to a malloced buffer. To ease
tracking the lifetime of this buffer let rpc_req return the packet data
and the caller free it when done using it. This reduces usage of global
data considerably and so makes the code easier to follow.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
Hello,

this is a more robust fix for 82ec28929cc9 breaking nfs on i.MX28 than
reported in the mail with Message-ID:
<20190114141717.nbs3h3nxnrrbizob@pengutronix.de>.

Best regards
Uwe

 fs/nfs.c | 137 +++++++++++++++++++++++++++++++++----------------------
 1 file changed, 82 insertions(+), 55 deletions(-)

diff --git a/fs/nfs.c b/fs/nfs.c
index d7f156687fc9..0fad28af331b 100644
--- a/fs/nfs.c
+++ b/fs/nfs.c
@@ -102,8 +102,12 @@
 #define NFS3ERR_BADTYPE		10007
 #define NFS3ERR_JUKEBOX		10008
 
-static void *nfs_packet;
-static int nfs_len;
+struct packet {
+	int len;
+	char data[];
+};
+
+static struct packet *nfs_packet;
 
 struct rpc_call {
 	uint32_t id;
@@ -355,8 +359,8 @@ static uint32_t *rpc_add_credentials(uint32_t *p)
 	return p;
 }
 
-static int rpc_check_reply(unsigned char *pkt,
-		int rpc_prog, uint32_t rpc_id, int *nfserr)
+static int rpc_check_reply(struct packet *pkt, int rpc_prog,
+			   uint32_t rpc_id, int *nfserr)
 {
 	uint32_t *data;
 	struct rpc_reply rpc;
@@ -366,7 +370,7 @@ static int rpc_check_reply(unsigned char *pkt,
 	if (!pkt)
 		return -EAGAIN;
 
-	memcpy(&rpc, pkt, sizeof(rpc));
+	memcpy(&rpc, pkt->data, sizeof(rpc));
 
 	if (ntoh32(rpc.id) != rpc_id) {
 		if (rpc_id - ntoh32(rpc.id) == 1)
@@ -385,7 +389,7 @@ static int rpc_check_reply(unsigned char *pkt,
 	if (rpc_prog == PROG_PORTMAP)
 		return 0;
 
-	data = (uint32_t *)(pkt + sizeof(struct rpc_reply));
+	data = (uint32_t *)(pkt->data + sizeof(struct rpc_reply));
 	*nfserr = ntoh32(net_read_uint32(data));
 	*nfserr = -*nfserr;
 
@@ -397,8 +401,8 @@ static int rpc_check_reply(unsigned char *pkt,
 /*
  * rpc_req - synchronous RPC request
  */
-static int rpc_req(struct nfs_priv *npriv, int rpc_prog, int rpc_proc,
-		uint32_t *data, int datalen)
+static struct packet *rpc_req(struct nfs_priv *npriv, int rpc_prog,
+			      int rpc_proc, uint32_t *data, int datalen)
 {
 	struct rpc_call pkt;
 	unsigned short dport;
@@ -440,31 +444,32 @@ again:
 	nfs_timer_start = get_time_ns();
 
 	nfs_state = STATE_START;
-	nfs_packet = NULL;
 
 	while (nfs_state != STATE_DONE) {
-		if (ctrlc()) {
-			ret = -EINTR;
-			break;
-		}
+		if (ctrlc())
+			return ERR_PTR(-EINTR);
+
 		net_poll();
 
 		if (is_timeout(nfs_timer_start, NFS_TIMEOUT)) {
 			tries++;
 			if (tries == NFS_MAX_RESEND)
-				return -ETIMEDOUT;
+				return ERR_PTR(-ETIMEDOUT);
 			goto again;
 		}
 
 		ret = rpc_check_reply(nfs_packet, rpc_prog,
-				npriv->rpc_id, &nfserr);
+				      npriv->rpc_id, &nfserr);
 		if (!ret) {
-			ret = nfserr;
-			break;
+			if (nfserr) {
+				free(nfs_packet);
+				return ERR_PTR(nfserr);
+			} else
+				return nfs_packet;
 		}
 	}
 
-	return ret;
+	return nfs_packet;
 }
 
 /*
@@ -473,7 +478,7 @@ again:
 static int rpc_lookup_req(struct nfs_priv *npriv, uint32_t prog, uint32_t ver)
 {
 	uint32_t data[16];
-	int ret;
+	struct packet *packet;
 	uint32_t port;
 
 	data[0] = 0; data[1] = 0;	/* auth credential */
@@ -483,11 +488,14 @@ static int rpc_lookup_req(struct nfs_priv *npriv, uint32_t prog, uint32_t ver)
 	data[6] = hton32(17);	/* IP_UDP */
 	data[7] = 0;
 
-	ret = rpc_req(npriv, PROG_PORTMAP, PORTMAP_GETPORT, data, 8);
-	if (ret)
-		return ret;
+	packet = rpc_req(npriv, PROG_PORTMAP, PORTMAP_GETPORT, data, 8);
+	if (IS_ERR(packet))
+		return PTR_ERR(packet);
+
+	port = ntoh32(net_read_uint32(packet->data + sizeof(struct rpc_reply)));
+
+	free(packet);
 
-	port = ntoh32(net_read_uint32(nfs_packet + sizeof(struct rpc_reply)));
 	return port;
 }
 
@@ -629,7 +637,7 @@ static int nfs_mount_req(struct nfs_priv *npriv)
 	uint32_t *p;
 	int len;
 	int pathlen;
-	int ret;
+	struct packet *packet;
 
 	pathlen = strlen(npriv->path);
 
@@ -647,20 +655,22 @@ static int nfs_mount_req(struct nfs_priv *npriv)
 
 	len = p - &(data[0]);
 
-	ret = rpc_req(npriv, PROG_MOUNT, MOUNT_ADDENTRY, data, len);
-	if (ret)
-		return ret;
+	packet = rpc_req(npriv, PROG_MOUNT, MOUNT_ADDENTRY, data, len);
+	if (IS_ERR(packet))
+		return PTR_ERR(packet);
 
-	p = nfs_packet + sizeof(struct rpc_reply) + 4;
+	p = (void *)packet->data + sizeof(struct rpc_reply) + 4;
 
 	npriv->rootfh.size = ntoh32(net_read_uint32(p++));
 	if (npriv->rootfh.size > NFS3_FHSIZE) {
-		printf("%s: file handle too big: %lu\n", __func__,
-				(unsigned long)npriv->rootfh.size);
+		printf("%s: file handle too big: %lu\n",
+		       __func__, (unsigned long)npriv->rootfh.size);
+		free(packet);
 		return -EIO;
 	}
 	memcpy(npriv->rootfh.data, p, npriv->rootfh.size);
-	p += DIV_ROUND_UP(npriv->rootfh.size, 4);
+
+	free(packet);
 
 	return 0;
 }
@@ -674,6 +684,7 @@ static void nfs_umount_req(struct nfs_priv *npriv)
 	uint32_t *p;
 	int len;
 	int pathlen;
+	struct packet *packet;
 
 	pathlen = strlen(npriv->path);
 
@@ -684,7 +695,10 @@ static void nfs_umount_req(struct nfs_priv *npriv)
 
 	len = p - &(data[0]);
 
-	rpc_req(npriv, PROG_MOUNT, MOUNT_UMOUNT, data, len);
+	packet = rpc_req(npriv, PROG_MOUNT, MOUNT_UMOUNT, data, len);
+
+	if (!IS_ERR(packet))
+		free(packet);
 }
 
 /*
@@ -699,7 +713,7 @@ static int nfs_lookup_req(struct nfs_priv *npriv, struct nfs_fh *fh,
 	uint32_t data[1024];
 	uint32_t *p;
 	int len;
-	int ret;
+	struct packet *packet;
 
 	/*
 	 * struct LOOKUP3args {
@@ -735,11 +749,11 @@ static int nfs_lookup_req(struct nfs_priv *npriv, struct nfs_fh *fh,
 
 	len = p - &(data[0]);
 
-	ret = rpc_req(npriv, PROG_NFS, NFSPROC3_LOOKUP, data, len);
-	if (ret)
-		return ret;
+	packet = rpc_req(npriv, PROG_NFS, NFSPROC3_LOOKUP, data, len);
+	if (IS_ERR(packet))
+		return PTR_ERR(packet);
 
-	p = nfs_packet + sizeof(struct rpc_reply) + 4;
+	p = (void *)packet->data + sizeof(struct rpc_reply) + 4;
 
 	ninode->fh.size = ntoh32(net_read_uint32(p++));
 	if (ninode->fh.size > NFS3_FHSIZE) {
@@ -752,6 +766,8 @@ static int nfs_lookup_req(struct nfs_priv *npriv, struct nfs_fh *fh,
 
 	nfs_read_post_op_attr(p, inode);
 
+	free(packet);
+
 	return 0;
 }
 
@@ -764,7 +780,7 @@ static void *nfs_readdirattr_req(struct nfs_priv *npriv, struct nfs_dir *dir)
 	uint32_t data[1024];
 	uint32_t *p;
 	int len;
-	int ret;
+	struct packet *packet;
 	void *buf;
 
 	/*
@@ -816,20 +832,21 @@ static void *nfs_readdirattr_req(struct nfs_priv *npriv, struct nfs_dir *dir)
 
 	p = nfs_add_uint32(p, 1024); /* count */
 
-	ret = rpc_req(npriv, PROG_NFS, NFSPROC3_READDIR, data, p - data);
-	if (ret)
+	packet = rpc_req(npriv, PROG_NFS, NFSPROC3_READDIR, data, p - data);
+	if (IS_ERR(packet))
 		return NULL;
 
-	p = nfs_packet + sizeof(struct rpc_reply) + 4;
+	p = (void *)packet->data + sizeof(struct rpc_reply) + 4;
 	p = nfs_read_post_op_attr(p, NULL);
 
 	/* update cookieverf */
 	memcpy(dir->cookieverf, p, NFS3_COOKIEVERFSIZE);
 	p += NFS3_COOKIEVERFSIZE / 4;
 
-	len = nfs_packet + nfs_len - (void *)p;
+	len = (void *)packet->data + packet->len - (void *)p;
 	if (!len) {
 		printf("%s: huh, no payload left\n", __func__);
+		free(packet);
 		return NULL;
 	}
 
@@ -837,6 +854,8 @@ static void *nfs_readdirattr_req(struct nfs_priv *npriv, struct nfs_dir *dir)
 
 	memcpy(buf, p, len);
 
+	free(packet);
+
 	xdr_init(&dir->stream, buf, len);
 
 	/* now xdr points to dirlist3 res.resok.reply */
@@ -853,7 +872,7 @@ static int nfs_read_req(struct file_priv *priv, uint64_t offset,
 	uint32_t data[1024];
 	uint32_t *p;
 	int len;
-	int ret;
+	struct packet *packet;
 	uint32_t rlen, eof;
 
 	/*
@@ -890,11 +909,11 @@ static int nfs_read_req(struct file_priv *priv, uint64_t offset,
 
 	len = p - &(data[0]);
 
-	ret = rpc_req(priv->npriv, PROG_NFS, NFSPROC3_READ, data, len);
-	if (ret)
-		return ret;
+	packet = rpc_req(priv->npriv, PROG_NFS, NFSPROC3_READ, data, len);
+	if (IS_ERR(packet))
+		return PTR_ERR(packet);
 
-	p = nfs_packet + sizeof(struct rpc_reply) + 4;
+	p = (void *)packet->data + sizeof(struct rpc_reply) + 4;
 
 	p = nfs_read_post_op_attr(p, NULL);
 
@@ -911,11 +930,15 @@ static int nfs_read_req(struct file_priv *priv, uint64_t offset,
 	 */
 	p += 2;
 
-	if (readlen && !rlen && !eof)
+	if (readlen && !rlen && !eof) {
+		free(packet);
 		return -EIO;
+	}
 
 	kfifo_put(priv->fifo, (char *)p, rlen);
 
+	free(packet);
+
 	return 0;
 }
 
@@ -924,8 +947,10 @@ static void nfs_handler(void *ctx, char *packet, unsigned len)
 	char *pkt = net_eth_to_udp_payload(packet);
 
 	nfs_state = STATE_DONE;
-	nfs_packet = pkt;
-	nfs_len = len;
+
+	nfs_packet = xmalloc(sizeof(*nfs_packet) + len);
+	memcpy(nfs_packet->data, pkt, len);
+	nfs_packet->len = len;
 }
 
 static int nfs_truncate(struct device_d *dev, FILE *f, ulong size)
@@ -947,7 +972,7 @@ static int nfs_readlink_req(struct nfs_priv *npriv, struct nfs_fh *fh,
 	uint32_t data[1024];
 	uint32_t *p;
 	uint32_t len;
-	int ret;
+	struct packet *packet;
 
 	/*
 	 * struct READLINK3args {
@@ -977,11 +1002,11 @@ static int nfs_readlink_req(struct nfs_priv *npriv, struct nfs_fh *fh,
 
 	len = p - &(data[0]);
 
-	ret = rpc_req(npriv, PROG_NFS, NFSPROC3_READLINK, data, len);
-	if (ret)
-		return ret;
+	packet = rpc_req(npriv, PROG_NFS, NFSPROC3_READLINK, data, len);
+	if (IS_ERR(packet))
+		return PTR_ERR(packet);
 
-	p = nfs_packet + sizeof(struct rpc_reply) + 4;
+	p = (void *)packet->data + sizeof(struct rpc_reply) + 4;
 
 	p = nfs_read_post_op_attr(p, NULL);
 
@@ -991,6 +1016,8 @@ static int nfs_readlink_req(struct nfs_priv *npriv, struct nfs_fh *fh,
 	*target = xzalloc(len + 1);
 	memcpy(*target, p, len);
 
+	free(packet);
+
 	return 0;
 }
 
-- 
2.20.1


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