net: ptp: do not reimplement PTP/BPF classifier

There are currently pch_gbe, cpts, and ixp4xx_eth drivers that open-code
and reimplement a BPF classifier for the PTP protocol. Since all of them
effectively do the very same thing and load the very same PTP/BPF filter,
we can just consolidate that code by introducing ptp_classify_raw() in
the time-stamping core framework which can be used in drivers.

As drivers get initialized after bootstrapping the core networking
subsystem, they can make use of ptp_insns wrapped through
ptp_classify_raw(), which allows to simplify and remove PTP classifier
setup code in drivers.

Joint work with Alexei Starovoitov.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Cc: Richard Cochran <richard.cochran@omicron.at>
Cc: Jiri Benc <jbenc@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/oki-semi/pch_gbe/pch_gbe_main.c

@@ -120,18 +120,14 @@ static void pch_gbe_mdio_write(struct net_device *netdev, int addr, int reg,
 			       int data);
 static void pch_gbe_set_multi(struct net_device *netdev);
 
-static struct sock_filter ptp_filter[] = {
-	PTP_FILTER
-};
-
 static int pch_ptp_match(struct sk_buff *skb, u16 uid_hi, u32 uid_lo, u16 seqid)
 {
 	u8 *data = skb->data;
 	unsigned int offset;
 	u16 *hi, *id;
 	u32 lo;
 
-	if (sk_run_filter(skb, ptp_filter) == PTP_CLASS_NONE)
+	if (ptp_classify_raw(skb) == PTP_CLASS_NONE)
 		return 0;
 
 	offset = ETH_HLEN + IPV4_HLEN(data) + UDP_HLEN;
@@ -2635,11 +2631,6 @@ static int pch_gbe_probe(struct pci_dev *pdev,
 
 	adapter->ptp_pdev = pci_get_bus_and_slot(adapter->pdev->bus->number,
 					       PCI_DEVFN(12, 4));
-	if (ptp_filter_init(ptp_filter, ARRAY_SIZE(ptp_filter))) {
-		dev_err(&pdev->dev, "Bad ptp filter\n");
-		ret = -EINVAL;
-		goto err_free_netdev;
-	}
 
 	netdev->netdev_ops = &pch_gbe_netdev_ops;
 	netdev->watchdog_timeo = PCH_GBE_WATCHDOG_PERIOD;

drivers/net/ethernet/ti/cpts.c

@@ -31,10 +31,6 @@
 
 #ifdef CONFIG_TI_CPTS
 
-static struct sock_filter ptp_filter[] = {
-	PTP_FILTER
-};
-
 #define cpts_read32(c, r)	__raw_readl(&c->reg->r)
 #define cpts_write32(c, v, r)	__raw_writel(v, &c->reg->r)
 
@@ -301,7 +297,7 @@ static u64 cpts_find_ts(struct cpts *cpts, struct sk_buff *skb, int ev_type)
 	u64 ns = 0;
 	struct cpts_event *event;
 	struct list_head *this, *next;
-	unsigned int class = sk_run_filter(skb, ptp_filter);
+	unsigned int class = ptp_classify_raw(skb);
 	unsigned long flags;
 	u16 seqid;
 	u8 mtype;
@@ -372,10 +368,6 @@ int cpts_register(struct device *dev, struct cpts *cpts,
 	int err, i;
 	unsigned long flags;
 
-	if (ptp_filter_init(ptp_filter, ARRAY_SIZE(ptp_filter))) {
-		pr_err("cpts: bad ptp filter\n");
-		return -EINVAL;
-	}
 	cpts->info = cpts_info;
 	cpts->clock = ptp_clock_register(&cpts->info, dev);
 	if (IS_ERR(cpts->clock)) {

drivers/net/ethernet/xscale/ixp4xx_eth.c

@@ -256,18 +256,14 @@ static int ports_open;
 static struct port *npe_port_tab[MAX_NPES];
 static struct dma_pool *dma_pool;
 
-static struct sock_filter ptp_filter[] = {
-	PTP_FILTER
-};
-
 static int ixp_ptp_match(struct sk_buff *skb, u16 uid_hi, u32 uid_lo, u16 seqid)
 {
 	u8 *data = skb->data;
 	unsigned int offset;
 	u16 *hi, *id;
 	u32 lo;
 
-	if (sk_run_filter(skb, ptp_filter) != PTP_CLASS_V1_IPV4)
+	if (ptp_classify_raw(skb) != PTP_CLASS_V1_IPV4)
 		return 0;
 
 	offset = ETH_HLEN + IPV4_HLEN(data) + UDP_HLEN;
@@ -1413,11 +1409,6 @@ static int eth_init_one(struct platform_device *pdev)
 	char phy_id[MII_BUS_ID_SIZE + 3];
 	int err;
 
-	if (ptp_filter_init(ptp_filter, ARRAY_SIZE(ptp_filter))) {
-		pr_err("ixp4xx_eth: bad ptp filter\n");
-		return -EINVAL;
-	}
-
 	if (!(dev = alloc_etherdev(sizeof(struct port))))
 		return -ENOMEM;
 

include/linux/ptp_classify.h

@@ -80,14 +80,6 @@
 #define OP_RETA	(BPF_RET | BPF_A)
 #define OP_RETK	(BPF_RET | BPF_K)
 
-static inline int ptp_filter_init(struct sock_filter *f, int len)
-{
-	if (OP_LDH == f[0].code)
-		return sk_chk_filter(f, len);
-	else
-		return 0;
-}
-
 #define PTP_FILTER \
 	{OP_LDH,	0,   0, OFF_ETYPE		}, /*              */ \
 	{OP_JEQ,	0,  12, ETH_P_IP		}, /* f goto L20   */ \
@@ -133,4 +125,6 @@ static inline int ptp_filter_init(struct sock_filter *f, int len)
 	{OP_RETA,	0,   0, 0			}, /*              */ \
 /*L6x*/	{OP_RETK,	0,   0, PTP_CLASS_NONE		},
 
+unsigned int ptp_classify_raw(const struct sk_buff *skb);
+
 #endif

net/core/timestamping.c

@@ -25,11 +25,17 @@
 
 static struct sk_filter *ptp_insns __read_mostly;
 
+unsigned int ptp_classify_raw(const struct sk_buff *skb)
+{
+	return SK_RUN_FILTER(ptp_insns, skb);
+}
+EXPORT_SYMBOL_GPL(ptp_classify_raw);
+
 static unsigned int classify(const struct sk_buff *skb)
 {
 	if (likely(skb->dev && skb->dev->phydev &&
 		   skb->dev->phydev->drv))
-		return SK_RUN_FILTER(ptp_insns, skb);
+		return ptp_classify_raw(skb);
 	else
 		return PTP_CLASS_NONE;
 }