Netstacklat: Add filtering and grouping

headers/vmlinux/vmlinux_net.h

@@ -3,6 +3,15 @@
 
 typedef __u32 __wsum;
 
+typedef struct {
+	struct net *net;
+} possible_net_t;
+
+struct net_device {
+	int ifindex;
+	possible_net_t nd_net;
+};
+
 typedef unsigned int sk_buff_data_t; // Assumes 64-bit. FIXME see below
 /*
 // BITS_PER_LONG can be wrong with -target bpf
@@ -17,6 +26,22 @@ typedef unsigned char *sk_buff_data_t;
 #endif
 */
 
+struct sk_buff_list {
+	struct sk_buff *next;
+	struct sk_buff *prev;
+};
+
+struct sk_buff_head {
+	union {
+		struct {
+			struct sk_buff *next;
+			struct sk_buff *prev;
+		};
+		struct sk_buff_list list;
+	};
+	__u32 qlen;
+};
+
 struct sk_buff {
 	union {
 		struct {
@@ -147,7 +172,28 @@ enum ip_conntrack_status {
 };
 
 struct scm_timestamping_internal {
-        struct timespec64 ts[3];
+	struct timespec64 ts[3];
+};
+
+struct ns_common {
+	struct dentry *stashed;
+	unsigned int inum;
+};
+
+struct net {
+	struct ns_common ns;
+};
+
+struct sock_common {
+	possible_net_t skc_net;
+};
+
+struct sock {
+	struct sock_common __sk_common;
+	struct sk_buff_head sk_receive_queue;
+	struct dst_entry *sk_rx_dst;
+	int sk_rx_dst_ifindex;
+	u32 sk_rx_dst_cookie;
 };
 
 #endif /* __VMLINUX_NET_H__ */

netstacklat/fill_filter_maps.sh

@@ -0,0 +1,131 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+declare -rA bpf_maps=(
+    [pid]="netstack_pidfil"
+    [iface]="netstack_ifinde"
+    [cgroup]="netstack_cgroup"
+)
+
+declare -rA key_converters=(
+    [pid]=pid_to_bpftool
+    [iface]=iface_to_bpftool
+    [cgroup]=cgroup_to_bpftool
+)
+
+print_usage()
+{
+    echo "usage: $0 TYPE val1 [val2 val3 val4...]"
+    echo "TYPE: { $(echo "${!bpf_maps[@]}" | tr ' ' '\|') }"
+}
+
+pid_to_bpftool()
+{
+    local val="$1"
+
+    uint_to_bpftool_u32 "$val"
+}
+
+# Supports ifname or ifindex
+iface_to_bpftool()
+{
+    local val="$1"
+
+    if ! is_uint "$val"; then
+	val="$(ifname_to_idx "$val")"
+    fi
+
+    uint_to_bpftool_u32 "$val"
+}
+
+# Supports full cgroup path or direct cgroup id (inode)
+cgroup_to_bpftool()
+{
+    local val="$1"
+
+    if ! is_uint "$val"; then
+	val="$(cgroup_path_to_id "$val")"
+    fi
+
+    uint_to_bpftool_u64 "$val"
+}
+
+is_uint()
+{
+    local val="$1"
+
+    [[ "$val" == +([0-9]) ]]
+}
+
+ifname_to_idx()
+{
+    local ifname="$1"
+    local ifindex=0
+
+    ifindex="$(ip address show "$ifname" | grep "[0-9]*: ${ifname}:")"
+    ifindex="${ifindex%%:*}"
+
+    if [[ -z "$ifindex" ]]; then
+	return 1
+    fi
+
+    echo "$ifindex"
+}
+
+cgroup_path_to_id()
+{
+    local cpath="$1"
+
+    stat -L -c '%i' "$(realpath "$cpath")"
+}
+
+# When providing keys/values to bpftool map update, it basically wants one
+# argument for each byte in the key/value. So if you have a u32 key (as in any
+# array map) and you want to update key 1234, then you will have to provide
+# key 0xd2 0x04 0x00 0x00 (1234 in hex split up as the 4 bytes in a u32 in
+# little-endian order). These helpers assume you're on a little endian machine.
+uint_to_bpftool_u32()
+{
+    local val="$1"
+
+    printf "0x%02x 0x%02x 0x%02x 0x%02x\n" \
+	   $((val & 0xff)) $(((val >> 8) & 0xff)) $(((val >> 16) & 0xff)) $(((val >> 24) & 0xff))
+}
+
+uint_to_bpftool_u64()
+{
+    printf "0x%02x 0x%02x 0x%02x 0x%02x 0x%02x 0x%02x 0x%02x 0x%02x\n" \
+	   $((val & 0xff)) $(((val >> 8) & 0xff)) $(((val >> 16) & 0xff)) $(((val >> 24) & 0xff)) \
+	   $(((val >> 32) & 0xff)) $(((val >> 40) & 0xff)) $(((val >> 48) & 0xff)) $(((val >> 56) & 0xff))
+}
+
+# All the filter maps use a u8 as the value, so just set that single byte to 1
+add_to_filter_map()
+{
+    local map="$1"
+    local key="$2"
+
+    bpftool map update name "$map" key $key value 1
+}
+
+if (( $# < 2 )); then
+    print_usage
+    exit 1
+fi
+
+type=$1
+if [[ -z "${bpf_maps[$type]}" ]]; then
+    echo "Error: unrecognized type $type, must be one of: ${!bpf_maps[*]}"
+    exit 1
+fi
+
+map=${bpf_maps[$type]}
+converter=${key_converters[$type]}
+
+for val in "${@:2}"; do
+    key=$($converter "$val")
+    if ! add_to_filter_map "$map" "$key"; then
+	echo "Error adding $val ($key) to map $map"
+	exit 1
+    fi
+done