| /* |
| * 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. |
| */ |
| |
| // The resulting .o needs to load on the Android T Beta 3 bpfloader |
| #define BPFLOADER_MIN_VER BPFLOADER_T_BETA3_VERSION |
| |
| #include <bpf_helpers.h> |
| #include <linux/bpf.h> |
| #include <linux/if.h> |
| #include <linux/if_ether.h> |
| #include <linux/if_packet.h> |
| #include <linux/in.h> |
| #include <linux/in6.h> |
| #include <linux/ip.h> |
| #include <linux/ipv6.h> |
| #include <linux/pkt_cls.h> |
| #include <linux/tcp.h> |
| #include <stdbool.h> |
| #include <stdint.h> |
| #include "bpf_net_helpers.h" |
| #include "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 |
| |
| // For maps netd does not need to access |
| #define DEFINE_BPF_MAP_NO_NETD(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries) \ |
| DEFINE_BPF_MAP_EXT(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries, \ |
| AID_ROOT, AID_NET_BW_ACCT, 0060, "fs_bpf_net_shared", "", false) |
| |
| // For maps netd only needs read only access to |
| #define DEFINE_BPF_MAP_RO_NETD(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries) \ |
| DEFINE_BPF_MAP_EXT(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries, \ |
| AID_ROOT, AID_NET_BW_ACCT, 0460, "fs_bpf_netd_readonly", "", false) |
| |
| // For maps netd needs to be able to read and write |
| #define DEFINE_BPF_MAP_RW_NETD(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries) \ |
| DEFINE_BPF_MAP_UGM(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries, \ |
| AID_ROOT, AID_NET_BW_ACCT, 0660) |
| |
| // Bpf map arrays on creation are preinitialized to 0 and do not support deletion of a key, |
| // see: kernel/bpf/arraymap.c array_map_delete_elem() returns -EINVAL (from both syscall and ebpf) |
| // Additionally on newer kernels the bpf jit can optimize out the lookups. |
| // only valid indexes are [0..CONFIGURATION_MAP_SIZE-1] |
| DEFINE_BPF_MAP_RO_NETD(configuration_map, ARRAY, uint32_t, uint32_t, CONFIGURATION_MAP_SIZE) |
| |
| DEFINE_BPF_MAP_RW_NETD(cookie_tag_map, HASH, uint64_t, UidTagValue, COOKIE_UID_MAP_SIZE) |
| DEFINE_BPF_MAP_NO_NETD(uid_counterset_map, HASH, uint32_t, uint8_t, UID_COUNTERSET_MAP_SIZE) |
| DEFINE_BPF_MAP_NO_NETD(app_uid_stats_map, HASH, uint32_t, StatsValue, APP_STATS_MAP_SIZE) |
| DEFINE_BPF_MAP_RW_NETD(stats_map_A, HASH, StatsKey, StatsValue, STATS_MAP_SIZE) |
| DEFINE_BPF_MAP_RO_NETD(stats_map_B, HASH, StatsKey, StatsValue, STATS_MAP_SIZE) |
| DEFINE_BPF_MAP_NO_NETD(iface_stats_map, HASH, uint32_t, StatsValue, IFACE_STATS_MAP_SIZE) |
| DEFINE_BPF_MAP_NO_NETD(uid_owner_map, HASH, uint32_t, UidOwnerValue, UID_OWNER_MAP_SIZE) |
| DEFINE_BPF_MAP_RW_NETD(uid_permission_map, HASH, uint32_t, uint8_t, UID_OWNER_MAP_SIZE) |
| |
| /* never actually used from ebpf */ |
| DEFINE_BPF_MAP_NO_NETD(iface_index_name_map, HASH, uint32_t, IfaceValue, IFACE_INDEX_NAME_MAP_SIZE) |
| |
| // iptables xt_bpf programs need to be usable by both netd and netutils_wrappers |
| #define DEFINE_XTBPF_PROG(SECTION_NAME, prog_uid, prog_gid, the_prog) \ |
| DEFINE_BPF_PROG(SECTION_NAME, prog_uid, prog_gid, the_prog) |
| |
| // programs that need to be usable by netd, but not by netutils_wrappers |
| #define DEFINE_NETD_BPF_PROG(SECTION_NAME, prog_uid, prog_gid, the_prog) \ |
| DEFINE_BPF_PROG_EXT(SECTION_NAME, prog_uid, prog_gid, the_prog, \ |
| KVER_NONE, KVER_INF, false, "fs_bpf_netd_readonly", "") |
| |
| // programs that only need to be usable by the system server |
| #define DEFINE_SYS_BPF_PROG(SECTION_NAME, prog_uid, prog_gid, the_prog) \ |
| DEFINE_BPF_PROG_EXT(SECTION_NAME, prog_uid, prog_gid, the_prog, \ |
| KVER_NONE, KVER_INF, false, "fs_bpf_net_shared", "") |
| |
| static __always_inline int is_system_uid(uint32_t uid) { |
| // MIN_SYSTEM_UID is AID_ROOT == 0, so uint32_t is *always* >= 0 |
| // MAX_SYSTEM_UID is AID_NOBODY == 9999, while AID_APP_START == 10000 |
| return (uid < AID_APP_START); |
| } |
| |
| /* |
| * 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; |
| } |
| |
| // DROP_IF_SET is set of rules that BPF_DROP if rule is globally enabled, and per-uid bit is set |
| #define DROP_IF_SET (STANDBY_MATCH | OEM_DENY_1_MATCH | OEM_DENY_2_MATCH | OEM_DENY_3_MATCH) |
| // DROP_IF_UNSET is set of rules that should DROP if globally enabled, and per-uid bit is NOT set |
| #define DROP_IF_UNSET (DOZABLE_MATCH | POWERSAVE_MATCH | RESTRICTED_MATCH | LOW_POWER_STANDBY_MATCH) |
| |
| 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); |
| uint32_t uidRules = uidEntry ? uidEntry->rule : 0; |
| uint32_t allowed_iif = uidEntry ? uidEntry->iif : 0; |
| |
| // Warning: funky bit-wise arithmetic: in parallel, for all DROP_IF_SET/UNSET rules |
| // check whether the rules are globally enabled, and if so whether the rules are |
| // set/unset for the specific uid. BPF_DROP if that is the case for ANY of the rules. |
| // We achieve this by masking out only the bits/rules we're interested in checking, |
| // and negating (via bit-wise xor) the bits/rules that should drop if unset. |
| if (enabledRules & (DROP_IF_SET | DROP_IF_UNSET) & (uidRules ^ DROP_IF_UNSET)) return BPF_DROP; |
| |
| if (direction == BPF_INGRESS && skb->ifindex != 1) { |
| if (uidRules & IIF_MATCH) { |
| if (allowed_iif && skb->ifindex != allowed_iif) { |
| // Drops packets not coming from lo nor the allowed interface |
| // allowed interface=0 is a wildcard and does not drop packets |
| return BPF_DROP_UNLESS_DNS; |
| } |
| } else if (uidRules & LOCKDOWN_VPN_MATCH) { |
| // Drops packets not coming from lo and rule does not have IIF_MATCH but has |
| // LOCKDOWN_VPN_MATCH |
| 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, uint32_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); |
| 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; |
| } |
| |
| // Always allow and never count clat traffic. Only the IPv4 traffic on the stacked |
| // interface is accounted for and subject to usage restrictions. |
| // TODO: remove sock_uid check once Nat464Xlat javaland adds the socket tag AID_CLAT for clat. |
| if (sock_uid == AID_CLAT || 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; |
| } |
| |
| // 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; |
| uint32_t* selectedMap = bpf_configuration_map_lookup_elem(&mapSettingKey); |
| |
| // Use asm("%0 &= 1" : "+r"(match)) before return match, |
| // to help kernel's bpf verifier, so that it can be 100% certain |
| // that the returned value is always BPF_NOMATCH(0) or BPF_MATCH(1). |
| if (!selectedMap) { |
| asm("%0 &= 1" : "+r"(match)); |
| 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); |
| asm("%0 &= 1" : "+r"(match)); |
| return match; |
| } |
| |
| DEFINE_NETD_BPF_PROG("cgroupskb/ingress/stats", AID_ROOT, AID_SYSTEM, bpf_cgroup_ingress) |
| (struct __sk_buff* skb) { |
| return bpf_traffic_account(skb, BPF_INGRESS); |
| } |
| |
| DEFINE_NETD_BPF_PROG("cgroupskb/egress/stats", AID_ROOT, AID_SYSTEM, bpf_cgroup_egress) |
| (struct __sk_buff* skb) { |
| return bpf_traffic_account(skb, BPF_EGRESS); |
| } |
| |
| // WARNING: Android T's non-updatable netd depends on the name of this program. |
| DEFINE_XTBPF_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). |
| // TODO: remove sock_uid check once Nat464Xlat javaland adds the socket tag AID_CLAT for clat. |
| uint32_t sock_uid = bpf_get_socket_uid(skb); |
| if (sock_uid == AID_CLAT) return BPF_NOMATCH; |
| if (sock_uid == AID_SYSTEM) { |
| uint64_t cookie = bpf_get_socket_cookie(skb); |
| UidTagValue* utag = bpf_cookie_tag_map_lookup_elem(&cookie); |
| if (utag && utag->uid == AID_CLAT) return BPF_NOMATCH; |
| } |
| |
| uint32_t key = skb->ifindex; |
| update_iface_stats_map(skb, BPF_EGRESS, &key); |
| return BPF_MATCH; |
| } |
| |
| // WARNING: Android T's non-updatable netd depends on the name of this program. |
| DEFINE_XTBPF_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_SYS_BPF_PROG("schedact/ingress/account", AID_ROOT, AID_NET_ADMIN, |
| tc_bpf_ingress_account_prog) |
| (struct __sk_buff* skb) { |
| if (is_received_skb(skb)) { |
| // Account for ingress traffic before tc drops it. |
| uint32_t key = skb->ifindex; |
| update_iface_stats_map(skb, BPF_INGRESS, &key); |
| } |
| return TC_ACT_UNSPEC; |
| } |
| |
| // WARNING: Android T's non-updatable netd depends on the name of this program. |
| DEFINE_XTBPF_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; |
| } |
| |
| // WARNING: Android T's non-updatable netd depends on the name of this program. |
| DEFINE_XTBPF_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_NETD_BPF_PROG("cgroupsock/inet/create", AID_ROOT, AID_ROOT, inet_socket_create) |
| (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) % AID_USER_OFFSET; // == PER_USER_RANGE == 100000 |
| 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"); |