um: Loadable BPF "Firmware" for vector drivers

All vector drivers now allow a BPF program to be loaded and
associated with the RX socket in the host kernel.

1. The program can be loaded as an extra kernel command line
option to any of the vector drivers.

2. The program can also be loaded as "firmware", using the
ethtool flash option. It is possible to turn this facility
on or off using a command line option.

A simplistic wrapper for generating the BPF firmware for the raw
socket driver out of a tcpdump/libpcap filter expression can be
found at: https://github.com/kot-begemot-uk/uml_vector_utilities/

Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

1 files changed, 104 insertions, 9 deletions

diff --git a/arch/um/drivers/vector_kern.c b/arch/um/drivers/vector_kern.c
index 769ffbd9e9a61..92617e16829e0 100644
--- a/arch/um/drivers/vector_kern.c
+++ b/arch/um/drivers/vector_kern.c
@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
- * Copyright (C) 2017 - Cambridge Greys Limited
+ * Copyright (C) 2017 - 2019 Cambridge Greys Limited
  * Copyright (C) 2011 - 2014 Cisco Systems Inc
  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org) and
@@ -21,6 +21,9 @@
 #include <linux/skbuff.h>
 #include <linux/slab.h>
 #include <linux/interrupt.h>
+#include <linux/firmware.h>
+#include <linux/fs.h>
+#include <uapi/linux/filter.h>
 #include <init.h>
 #include <irq_kern.h>
 #include <irq_user.h>
@@ -128,6 +131,23 @@ static int get_mtu(struct arglist *def)
 	return ETH_MAX_PACKET;
 }
 
+static char *get_bpf_file(struct arglist *def)
+{
+	return uml_vector_fetch_arg(def, "bpffile");
+}
+
+static bool get_bpf_flash(struct arglist *def)
+{
+	char *allow = uml_vector_fetch_arg(def, "bpfflash");
+	long result;
+
+	if (allow != NULL) {
+		if (kstrtoul(allow, 10, &result) == 0)
+			return (allow > 0);
+	}
+	return false;
+}
+
 static int get_depth(struct arglist *def)
 {
 	char *mtu = uml_vector_fetch_arg(def, "depth");
@@ -176,6 +196,7 @@ static int get_transport_options(struct arglist *def)
 	int vec_rx = VECTOR_RX;
 	int vec_tx = VECTOR_TX;
 	long parsed;
+	int result = 0;
 
 	if (vector != NULL) {
 		if (kstrtoul(vector, 10, &parsed) == 0) {
@@ -186,14 +207,16 @@ static int get_transport_options(struct arglist *def)
 		}
 	}
 
+	if (get_bpf_flash(def))
+		result = VECTOR_BPF_FLASH;
 
 	if (strncmp(transport, TRANS_TAP, TRANS_TAP_LEN) == 0)
-		return 0;
+		return result;
 	if (strncmp(transport, TRANS_HYBRID, TRANS_HYBRID_LEN) == 0)
-		return (vec_rx | VECTOR_BPF);
+		return (result | vec_rx | VECTOR_BPF);
 	if (strncmp(transport, TRANS_RAW, TRANS_RAW_LEN) == 0)
-		return (vec_rx | vec_tx | VECTOR_QDISC_BYPASS);
-	return (vec_rx | vec_tx);
+		return (result | vec_rx | vec_tx | VECTOR_QDISC_BYPASS);
+	return (result | vec_rx | vec_tx);
 }
 
 
@@ -1139,6 +1162,8 @@ static int vector_net_close(struct net_device *dev)
 	}
 	tasklet_kill(&vp->tx_poll);
 	if (vp->fds->rx_fd > 0) {
+		if (vp->bpf)
+			uml_vector_detach_bpf(vp->fds->rx_fd, vp->bpf);
 		os_close_file(vp->fds->rx_fd);
 		vp->fds->rx_fd = -1;
 	}
@@ -1146,7 +1171,10 @@ static int vector_net_close(struct net_device *dev)
 		os_close_file(vp->fds->tx_fd);
 		vp->fds->tx_fd = -1;
 	}
+	if (vp->bpf != NULL)
+		kfree(vp->bpf->filter);
 	kfree(vp->bpf);
+	vp->bpf = NULL;
 	kfree(vp->fds->remote_addr);
 	kfree(vp->transport_data);
 	kfree(vp->header_rxbuffer);
@@ -1181,6 +1209,7 @@ static void vector_reset_tx(struct work_struct *work)
 	netif_start_queue(vp->dev);
 	netif_wake_queue(vp->dev);
 }
+
 static int vector_net_open(struct net_device *dev)
 {
 	struct vector_private *vp = netdev_priv(dev);
@@ -1196,6 +1225,8 @@ static int vector_net_open(struct net_device *dev)
 	vp->opened = true;
 	spin_unlock_irqrestore(&vp->lock, flags);
 
+	vp->bpf = uml_vector_user_bpf(get_bpf_file(vp->parsed));
+
 	vp->fds = uml_vector_user_open(vp->unit, vp->parsed);
 
 	if (vp->fds == NULL)
@@ -1267,8 +1298,11 @@ static int vector_net_open(struct net_device *dev)
 		if (!uml_raw_enable_qdisc_bypass(vp->fds->rx_fd))
 			vp->options |= VECTOR_BPF;
 	}
-	if ((vp->options & VECTOR_BPF) != 0)
-		vp->bpf = uml_vector_default_bpf(vp->fds->rx_fd, dev->dev_addr);
+	if (((vp->options & VECTOR_BPF) != 0) && (vp->bpf == NULL))
+		vp->bpf = uml_vector_default_bpf(dev->dev_addr);
+
+	if (vp->bpf != NULL)
+		uml_vector_attach_bpf(vp->fds->rx_fd, vp->bpf);
 
 	netif_start_queue(dev);
 
@@ -1347,6 +1381,65 @@ static void vector_net_get_drvinfo(struct net_device *dev,
 	strlcpy(info->version, DRIVER_VERSION, sizeof(info->version));
 }
 
+static int vector_net_load_bpf_flash(struct net_device *dev,
+				struct ethtool_flash *efl)
+{
+	struct vector_private *vp = netdev_priv(dev);
+	struct vector_device *vdevice;
+	const struct firmware *fw;
+	int result = 0;
+
+	if (!(vp->options & VECTOR_BPF_FLASH)) {
+		netdev_err(dev, "loading firmware not permitted: %s\n", efl->data);
+		return -1;
+	}
+
+	spin_lock(&vp->lock);
+
+	if (vp->bpf != NULL) {
+		if (vp->opened)
+			uml_vector_detach_bpf(vp->fds->rx_fd, vp->bpf);
+		kfree(vp->bpf->filter);
+		vp->bpf->filter = NULL;
+	} else {
+		vp->bpf = kmalloc(sizeof(struct sock_fprog), GFP_KERNEL);
+		if (vp->bpf == NULL) {
+			netdev_err(dev, "failed to allocate memory for firmware\n");
+			goto flash_fail;
+		}
+	}
+
+	vdevice = find_device(vp->unit);
+
+	if (request_firmware(&fw, efl->data, &vdevice->pdev.dev))
+		goto flash_fail;
+
+	vp->bpf->filter = kmemdup(fw->data, fw->size, GFP_KERNEL);
+	if (!vp->bpf->filter)
+		goto free_buffer;
+
+	vp->bpf->len = fw->size / sizeof(struct sock_filter);
+	release_firmware(fw);
+
+	if (vp->opened)
+		result = uml_vector_attach_bpf(vp->fds->rx_fd, vp->bpf);
+
+	spin_unlock(&vp->lock);
+
+	return result;
+
+free_buffer:
+	release_firmware(fw);
+
+flash_fail:
+	spin_unlock(&vp->lock);
+	if (vp->bpf != NULL)
+		kfree(vp->bpf->filter);
+	kfree(vp->bpf);
+	vp->bpf = NULL;
+	return -1;
+}
+
 static void vector_get_ringparam(struct net_device *netdev,
 				struct ethtool_ringparam *ring)
 {
@@ -1424,6 +1517,7 @@ static const struct ethtool_ops vector_net_ethtool_ops = {
 	.get_ethtool_stats = vector_get_ethtool_stats,
 	.get_coalesce	= vector_get_coalesce,
 	.set_coalesce	= vector_set_coalesce,
+	.flash_device	= vector_net_load_bpf_flash,
 };
 
 
@@ -1528,8 +1622,9 @@ static void vector_eth_configure(
 		.in_write_poll		= false,
 		.coalesce		= 2,
 		.req_size		= get_req_size(def),
-		.in_error		= false
-		});
+		.in_error		= false,
+		.bpf			= NULL
+	});
 
 	dev->features = dev->hw_features = (NETIF_F_SG | NETIF_F_FRAGLIST);
 	tasklet_init(&vp->tx_poll, vector_tx_poll, (unsigned long)vp);