/* * Copyright (C) 2018 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #include #include #include #include #include #include #include #include #include #include #include #include #include "bpf_net_helpers.h" #include "netdbpf/bpf_shared.h" // This is defined for cgroup bpf filter only. #define BPF_DROP_UNLESS_DNS 2 #define BPF_PASS 1 #define BPF_DROP 0 // This is used for xt_bpf program only. #define BPF_NOMATCH 0 #define BPF_MATCH 1 #define BPF_EGRESS 0 #define BPF_INGRESS 1 #define IP_PROTO_OFF offsetof(struct iphdr, protocol) #define IPV6_PROTO_OFF offsetof(struct ipv6hdr, nexthdr) #define IPPROTO_IHL_OFF 0 #define TCP_FLAG_OFF 13 #define RST_OFFSET 2 DEFINE_BPF_MAP_GRO(cookie_tag_map, HASH, uint64_t, UidTagValue, COOKIE_UID_MAP_SIZE, AID_NET_BW_ACCT) DEFINE_BPF_MAP_GRO(uid_counterset_map, HASH, uint32_t, uint8_t, UID_COUNTERSET_MAP_SIZE, AID_NET_BW_ACCT) DEFINE_BPF_MAP_GRO(app_uid_stats_map, HASH, uint32_t, StatsValue, APP_STATS_MAP_SIZE, AID_NET_BW_STATS) DEFINE_BPF_MAP_GRW(stats_map_A, HASH, StatsKey, StatsValue, STATS_MAP_SIZE, AID_NET_BW_STATS) DEFINE_BPF_MAP_GRW(stats_map_B, HASH, StatsKey, StatsValue, STATS_MAP_SIZE, AID_NET_BW_STATS) DEFINE_BPF_MAP_GRO(iface_stats_map, HASH, uint32_t, StatsValue, IFACE_STATS_MAP_SIZE, AID_NET_BW_STATS) DEFINE_BPF_MAP_GRO(configuration_map, HASH, uint32_t, uint8_t, CONFIGURATION_MAP_SIZE, AID_NET_BW_STATS) DEFINE_BPF_MAP(uid_owner_map, HASH, uint32_t, UidOwnerValue, UID_OWNER_MAP_SIZE) /* never actually used from ebpf */ DEFINE_BPF_MAP_GRO(iface_index_name_map, HASH, uint32_t, IfaceValue, IFACE_INDEX_NAME_MAP_SIZE, AID_NET_BW_STATS) static __always_inline int is_system_uid(uint32_t uid) { return (uid <= MAX_SYSTEM_UID) && (uid >= MIN_SYSTEM_UID); } /* * Note: this blindly assumes an MTU of 1500, and that packets > MTU are always TCP, * and that TCP is using the Linux default settings with TCP timestamp option enabled * which uses 12 TCP option bytes per frame. * * These are not unreasonable assumptions: * * The internet does not really support MTUs greater than 1500, so most TCP traffic will * be at that MTU, or slightly below it (worst case our upwards adjustment is too small). * * The chance our traffic isn't IP at all is basically zero, so the IP overhead correction * is bound to be needed. * * Furthermore, the likelyhood that we're having to deal with GSO (ie. > MTU) packets that * are not IP/TCP is pretty small (few other things are supported by Linux) and worse case * our extra overhead will be slightly off, but probably still better than assuming none. * * Most servers are also Linux and thus support/default to using TCP timestamp option * (and indeed TCP timestamp option comes from RFC 1323 titled "TCP Extensions for High * Performance" which also defined TCP window scaling and are thus absolutely ancient...). * * All together this should be more correct than if we simply ignored GSO frames * (ie. counted them as single packets with no extra overhead) * * Especially since the number of packets is important for any future clat offload correction. * (which adjusts upward by 20 bytes per packet to account for ipv4 -> ipv6 header conversion) */ #define DEFINE_UPDATE_STATS(the_stats_map, TypeOfKey) \ static __always_inline inline void update_##the_stats_map(struct __sk_buff* skb, \ int direction, TypeOfKey* key) { \ StatsValue* value = bpf_##the_stats_map##_lookup_elem(key); \ if (!value) { \ StatsValue newValue = {}; \ bpf_##the_stats_map##_update_elem(key, &newValue, BPF_NOEXIST); \ value = bpf_##the_stats_map##_lookup_elem(key); \ } \ if (value) { \ const int mtu = 1500; \ uint64_t packets = 1; \ uint64_t bytes = skb->len; \ if (bytes > mtu) { \ bool is_ipv6 = (skb->protocol == htons(ETH_P_IPV6)); \ int ip_overhead = (is_ipv6 ? sizeof(struct ipv6hdr) : sizeof(struct iphdr)); \ int tcp_overhead = ip_overhead + sizeof(struct tcphdr) + 12; \ int mss = mtu - tcp_overhead; \ uint64_t payload = bytes - tcp_overhead; \ packets = (payload + mss - 1) / mss; \ bytes = tcp_overhead * packets + payload; \ } \ if (direction == BPF_EGRESS) { \ __sync_fetch_and_add(&value->txPackets, packets); \ __sync_fetch_and_add(&value->txBytes, bytes); \ } else if (direction == BPF_INGRESS) { \ __sync_fetch_and_add(&value->rxPackets, packets); \ __sync_fetch_and_add(&value->rxBytes, bytes); \ } \ } \ } DEFINE_UPDATE_STATS(app_uid_stats_map, uint32_t) DEFINE_UPDATE_STATS(iface_stats_map, uint32_t) DEFINE_UPDATE_STATS(stats_map_A, StatsKey) DEFINE_UPDATE_STATS(stats_map_B, StatsKey) static inline bool skip_owner_match(struct __sk_buff* skb) { int offset = -1; int ret = 0; if (skb->protocol == htons(ETH_P_IP)) { offset = IP_PROTO_OFF; uint8_t proto, ihl; uint8_t flag; ret = bpf_skb_load_bytes(skb, offset, &proto, 1); if (!ret) { if (proto == IPPROTO_ESP) { return true; } else if (proto == IPPROTO_TCP) { ret = bpf_skb_load_bytes(skb, IPPROTO_IHL_OFF, &ihl, 1); ihl = ihl & 0x0F; ret = bpf_skb_load_bytes(skb, ihl * 4 + TCP_FLAG_OFF, &flag, 1); if (ret == 0 && (flag >> RST_OFFSET & 1)) { return true; } } } } else if (skb->protocol == htons(ETH_P_IPV6)) { offset = IPV6_PROTO_OFF; uint8_t proto; ret = bpf_skb_load_bytes(skb, offset, &proto, 1); if (!ret) { if (proto == IPPROTO_ESP) { return true; } else if (proto == IPPROTO_TCP) { uint8_t flag; ret = bpf_skb_load_bytes(skb, sizeof(struct ipv6hdr) + TCP_FLAG_OFF, &flag, 1); if (ret == 0 && (flag >> RST_OFFSET & 1)) { return true; } } } } return false; } static __always_inline BpfConfig getConfig(uint32_t configKey) { uint32_t mapSettingKey = configKey; BpfConfig* config = bpf_configuration_map_lookup_elem(&mapSettingKey); if (!config) { // Couldn't read configuration entry. Assume everything is disabled. return DEFAULT_CONFIG; } return *config; } static inline int bpf_owner_match(struct __sk_buff* skb, uint32_t uid, int direction) { if (skip_owner_match(skb)) return BPF_PASS; if (is_system_uid(uid)) return BPF_PASS; BpfConfig enabledRules = getConfig(UID_RULES_CONFIGURATION_KEY); UidOwnerValue* uidEntry = bpf_uid_owner_map_lookup_elem(&uid); uint8_t uidRules = uidEntry ? uidEntry->rule : 0; uint32_t allowed_iif = uidEntry ? uidEntry->iif : 0; if (enabledRules) { if ((enabledRules & DOZABLE_MATCH) && !(uidRules & DOZABLE_MATCH)) { return BPF_DROP; } if ((enabledRules & STANDBY_MATCH) && (uidRules & STANDBY_MATCH)) { return BPF_DROP; } if ((enabledRules & POWERSAVE_MATCH) && !(uidRules & POWERSAVE_MATCH)) { return BPF_DROP; } } if (direction == BPF_INGRESS && (uidRules & IIF_MATCH)) { // Drops packets not coming from lo nor the allowlisted interface if (allowed_iif && skb->ifindex != 1 && skb->ifindex != allowed_iif) { return BPF_DROP_UNLESS_DNS; } } return BPF_PASS; } static __always_inline inline void update_stats_with_config(struct __sk_buff* skb, int direction, StatsKey* key, uint8_t selectedMap) { if (selectedMap == SELECT_MAP_A) { update_stats_map_A(skb, direction, key); } else if (selectedMap == SELECT_MAP_B) { update_stats_map_B(skb, direction, key); } } static __always_inline inline int bpf_traffic_account(struct __sk_buff* skb, int direction) { uint32_t sock_uid = bpf_get_socket_uid(skb); // Always allow and never count clat traffic. Only the IPv4 traffic on the stacked // interface is accounted for and subject to usage restrictions. if (sock_uid == AID_CLAT) { return BPF_PASS; } int match = bpf_owner_match(skb, sock_uid, direction); if ((direction == BPF_EGRESS) && (match == BPF_DROP)) { // If an outbound packet is going to be dropped, we do not count that // traffic. return match; } uint64_t cookie = bpf_get_socket_cookie(skb); UidTagValue* utag = bpf_cookie_tag_map_lookup_elem(&cookie); uint32_t uid, tag; if (utag) { uid = utag->uid; tag = utag->tag; } else { uid = sock_uid; tag = 0; } // Workaround for secureVPN with VpnIsolation enabled, refer to b/159994981 for details. // Keep TAG_SYSTEM_DNS in sync with DnsResolver/include/netd_resolv/resolv.h // and TrafficStatsConstants.java #define TAG_SYSTEM_DNS 0xFFFFFF82 if (tag == TAG_SYSTEM_DNS && uid == AID_DNS) { uid = sock_uid; if (match == BPF_DROP_UNLESS_DNS) match = BPF_PASS; } else { if (match == BPF_DROP_UNLESS_DNS) match = BPF_DROP; } StatsKey key = {.uid = uid, .tag = tag, .counterSet = 0, .ifaceIndex = skb->ifindex}; uint8_t* counterSet = bpf_uid_counterset_map_lookup_elem(&uid); if (counterSet) key.counterSet = (uint32_t)*counterSet; uint32_t mapSettingKey = CURRENT_STATS_MAP_CONFIGURATION_KEY; uint8_t* selectedMap = bpf_configuration_map_lookup_elem(&mapSettingKey); if (!selectedMap) { return match; } if (key.tag) { update_stats_with_config(skb, direction, &key, *selectedMap); key.tag = 0; } update_stats_with_config(skb, direction, &key, *selectedMap); update_app_uid_stats_map(skb, direction, &uid); return match; } SEC("cgroupskb/ingress/stats") int bpf_cgroup_ingress(struct __sk_buff* skb) { return bpf_traffic_account(skb, BPF_INGRESS); } SEC("cgroupskb/egress/stats") int bpf_cgroup_egress(struct __sk_buff* skb) { return bpf_traffic_account(skb, BPF_EGRESS); } DEFINE_BPF_PROG("skfilter/egress/xtbpf", AID_ROOT, AID_NET_ADMIN, xt_bpf_egress_prog) (struct __sk_buff* skb) { // Clat daemon does not generate new traffic, all its traffic is accounted for already // on the v4-* interfaces (except for the 20 (or 28) extra bytes of IPv6 vs IPv4 overhead, // but that can be corrected for later when merging v4-foo stats into interface foo's). uint32_t sock_uid = bpf_get_socket_uid(skb); if (sock_uid == AID_CLAT) return BPF_NOMATCH; uint32_t key = skb->ifindex; update_iface_stats_map(skb, BPF_EGRESS, &key); return BPF_MATCH; } DEFINE_BPF_PROG("skfilter/ingress/xtbpf", AID_ROOT, AID_NET_ADMIN, xt_bpf_ingress_prog) (struct __sk_buff* skb) { // Clat daemon traffic is not accounted by virtue of iptables raw prerouting drop rule // (in clat_raw_PREROUTING chain), which triggers before this (in bw_raw_PREROUTING chain). // It will be accounted for on the v4-* clat interface instead. // Keep that in mind when moving this out of iptables xt_bpf and into tc ingress (or xdp). uint32_t key = skb->ifindex; update_iface_stats_map(skb, BPF_INGRESS, &key); return BPF_MATCH; } DEFINE_BPF_PROG("skfilter/allowlist/xtbpf", AID_ROOT, AID_NET_ADMIN, xt_bpf_allowlist_prog) (struct __sk_buff* skb) { uint32_t sock_uid = bpf_get_socket_uid(skb); if (is_system_uid(sock_uid)) return BPF_MATCH; // 65534 is the overflow 'nobody' uid, usually this being returned means // that skb->sk is NULL during RX (early decap socket lookup failure), // which commonly happens for incoming packets to an unconnected udp socket. // Additionally bpf_get_socket_cookie() returns 0 if skb->sk is NULL if ((sock_uid == 65534) && !bpf_get_socket_cookie(skb) && is_received_skb(skb)) return BPF_MATCH; UidOwnerValue* allowlistMatch = bpf_uid_owner_map_lookup_elem(&sock_uid); if (allowlistMatch) return allowlistMatch->rule & HAPPY_BOX_MATCH ? BPF_MATCH : BPF_NOMATCH; return BPF_NOMATCH; } DEFINE_BPF_PROG("skfilter/denylist/xtbpf", AID_ROOT, AID_NET_ADMIN, xt_bpf_denylist_prog) (struct __sk_buff* skb) { uint32_t sock_uid = bpf_get_socket_uid(skb); UidOwnerValue* denylistMatch = bpf_uid_owner_map_lookup_elem(&sock_uid); if (denylistMatch) return denylistMatch->rule & PENALTY_BOX_MATCH ? BPF_MATCH : BPF_NOMATCH; return BPF_NOMATCH; } DEFINE_BPF_MAP(uid_permission_map, HASH, uint32_t, uint8_t, UID_OWNER_MAP_SIZE) DEFINE_BPF_PROG_KVER("cgroupsock/inet/create", AID_ROOT, AID_ROOT, inet_socket_create, KVER(4, 14, 0)) (struct bpf_sock* sk) { uint64_t gid_uid = bpf_get_current_uid_gid(); /* * A given app is guaranteed to have the same app ID in all the profiles in * which it is installed, and install permission is granted to app for all * user at install time so we only check the appId part of a request uid at * run time. See UserHandle#isSameApp for detail. */ uint32_t appId = (gid_uid & 0xffffffff) % PER_USER_RANGE; uint8_t* permissions = bpf_uid_permission_map_lookup_elem(&appId); if (!permissions) { // UID not in map. Default to just INTERNET permission. return 1; } // A return value of 1 means allow, everything else means deny. return (*permissions & BPF_PERMISSION_INTERNET) == BPF_PERMISSION_INTERNET; } LICENSE("Apache 2.0"); CRITICAL("netd");