451 lines
20 KiB
C
451 lines
20 KiB
C
/*
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* Copyright (C) 2018 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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// The resulting .o needs to load on the Android T Beta 3 bpfloader
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#define BPFLOADER_MIN_VER BPFLOADER_T_BETA3_VERSION
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#include <bpf_helpers.h>
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#include <linux/bpf.h>
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#include <linux/if.h>
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#include <linux/if_ether.h>
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#include <linux/if_packet.h>
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#include <linux/in.h>
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#include <linux/in6.h>
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#include <linux/ip.h>
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#include <linux/ipv6.h>
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#include <linux/pkt_cls.h>
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#include <linux/tcp.h>
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#include <stdbool.h>
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#include <stdint.h>
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#include "bpf_net_helpers.h"
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#include "bpf_shared.h"
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// This is defined for cgroup bpf filter only.
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#define BPF_DROP_UNLESS_DNS 2
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#define BPF_PASS 1
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#define BPF_DROP 0
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// This is used for xt_bpf program only.
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#define BPF_NOMATCH 0
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#define BPF_MATCH 1
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#define BPF_EGRESS 0
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#define BPF_INGRESS 1
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#define IP_PROTO_OFF offsetof(struct iphdr, protocol)
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#define IPV6_PROTO_OFF offsetof(struct ipv6hdr, nexthdr)
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#define IPPROTO_IHL_OFF 0
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#define TCP_FLAG_OFF 13
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#define RST_OFFSET 2
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// For maps netd does not need to access
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#define DEFINE_BPF_MAP_NO_NETD(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries) \
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DEFINE_BPF_MAP_EXT(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries, \
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AID_ROOT, AID_NET_BW_ACCT, 0060, "fs_bpf_net_shared", "", false)
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// For maps netd only needs read only access to
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#define DEFINE_BPF_MAP_RO_NETD(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries) \
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DEFINE_BPF_MAP_EXT(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries, \
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AID_ROOT, AID_NET_BW_ACCT, 0460, "fs_bpf_netd_readonly", "", false)
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// For maps netd needs to be able to read and write
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#define DEFINE_BPF_MAP_RW_NETD(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries) \
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DEFINE_BPF_MAP_UGM(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries, \
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AID_ROOT, AID_NET_BW_ACCT, 0660)
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// Bpf map arrays on creation are preinitialized to 0 and do not support deletion of a key,
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// see: kernel/bpf/arraymap.c array_map_delete_elem() returns -EINVAL (from both syscall and ebpf)
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// Additionally on newer kernels the bpf jit can optimize out the lookups.
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// only valid indexes are [0..CONFIGURATION_MAP_SIZE-1]
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DEFINE_BPF_MAP_RO_NETD(configuration_map, ARRAY, uint32_t, uint32_t, CONFIGURATION_MAP_SIZE)
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DEFINE_BPF_MAP_RW_NETD(cookie_tag_map, HASH, uint64_t, UidTagValue, COOKIE_UID_MAP_SIZE)
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DEFINE_BPF_MAP_NO_NETD(uid_counterset_map, HASH, uint32_t, uint8_t, UID_COUNTERSET_MAP_SIZE)
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DEFINE_BPF_MAP_NO_NETD(app_uid_stats_map, HASH, uint32_t, StatsValue, APP_STATS_MAP_SIZE)
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DEFINE_BPF_MAP_RW_NETD(stats_map_A, HASH, StatsKey, StatsValue, STATS_MAP_SIZE)
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DEFINE_BPF_MAP_RO_NETD(stats_map_B, HASH, StatsKey, StatsValue, STATS_MAP_SIZE)
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DEFINE_BPF_MAP_NO_NETD(iface_stats_map, HASH, uint32_t, StatsValue, IFACE_STATS_MAP_SIZE)
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DEFINE_BPF_MAP_NO_NETD(uid_owner_map, HASH, uint32_t, UidOwnerValue, UID_OWNER_MAP_SIZE)
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DEFINE_BPF_MAP_RW_NETD(uid_permission_map, HASH, uint32_t, uint8_t, UID_OWNER_MAP_SIZE)
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/* never actually used from ebpf */
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DEFINE_BPF_MAP_NO_NETD(iface_index_name_map, HASH, uint32_t, IfaceValue, IFACE_INDEX_NAME_MAP_SIZE)
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// iptables xt_bpf programs need to be usable by both netd and netutils_wrappers
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#define DEFINE_XTBPF_PROG(SECTION_NAME, prog_uid, prog_gid, the_prog) \
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DEFINE_BPF_PROG(SECTION_NAME, prog_uid, prog_gid, the_prog)
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// programs that need to be usable by netd, but not by netutils_wrappers
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#define DEFINE_NETD_BPF_PROG(SECTION_NAME, prog_uid, prog_gid, the_prog) \
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DEFINE_BPF_PROG_EXT(SECTION_NAME, prog_uid, prog_gid, the_prog, \
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KVER_NONE, KVER_INF, false, "fs_bpf_netd_readonly", "")
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// programs that only need to be usable by the system server
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#define DEFINE_SYS_BPF_PROG(SECTION_NAME, prog_uid, prog_gid, the_prog) \
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DEFINE_BPF_PROG_EXT(SECTION_NAME, prog_uid, prog_gid, the_prog, \
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KVER_NONE, KVER_INF, false, "fs_bpf_net_shared", "")
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static __always_inline int is_system_uid(uint32_t uid) {
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// MIN_SYSTEM_UID is AID_ROOT == 0, so uint32_t is *always* >= 0
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// MAX_SYSTEM_UID is AID_NOBODY == 9999, while AID_APP_START == 10000
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return (uid < AID_APP_START);
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}
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/*
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* Note: this blindly assumes an MTU of 1500, and that packets > MTU are always TCP,
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* and that TCP is using the Linux default settings with TCP timestamp option enabled
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* which uses 12 TCP option bytes per frame.
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*
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* These are not unreasonable assumptions:
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*
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* The internet does not really support MTUs greater than 1500, so most TCP traffic will
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* be at that MTU, or slightly below it (worst case our upwards adjustment is too small).
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*
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* The chance our traffic isn't IP at all is basically zero, so the IP overhead correction
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* is bound to be needed.
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*
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* Furthermore, the likelyhood that we're having to deal with GSO (ie. > MTU) packets that
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* are not IP/TCP is pretty small (few other things are supported by Linux) and worse case
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* our extra overhead will be slightly off, but probably still better than assuming none.
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*
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* Most servers are also Linux and thus support/default to using TCP timestamp option
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* (and indeed TCP timestamp option comes from RFC 1323 titled "TCP Extensions for High
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* Performance" which also defined TCP window scaling and are thus absolutely ancient...).
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*
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* All together this should be more correct than if we simply ignored GSO frames
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* (ie. counted them as single packets with no extra overhead)
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*
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* Especially since the number of packets is important for any future clat offload correction.
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* (which adjusts upward by 20 bytes per packet to account for ipv4 -> ipv6 header conversion)
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*/
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#define DEFINE_UPDATE_STATS(the_stats_map, TypeOfKey) \
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static __always_inline inline void update_##the_stats_map(struct __sk_buff* skb, \
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int direction, TypeOfKey* key) { \
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StatsValue* value = bpf_##the_stats_map##_lookup_elem(key); \
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if (!value) { \
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StatsValue newValue = {}; \
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bpf_##the_stats_map##_update_elem(key, &newValue, BPF_NOEXIST); \
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value = bpf_##the_stats_map##_lookup_elem(key); \
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} \
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if (value) { \
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const int mtu = 1500; \
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uint64_t packets = 1; \
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uint64_t bytes = skb->len; \
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if (bytes > mtu) { \
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bool is_ipv6 = (skb->protocol == htons(ETH_P_IPV6)); \
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int ip_overhead = (is_ipv6 ? sizeof(struct ipv6hdr) : sizeof(struct iphdr)); \
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int tcp_overhead = ip_overhead + sizeof(struct tcphdr) + 12; \
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int mss = mtu - tcp_overhead; \
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uint64_t payload = bytes - tcp_overhead; \
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packets = (payload + mss - 1) / mss; \
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bytes = tcp_overhead * packets + payload; \
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} \
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if (direction == BPF_EGRESS) { \
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__sync_fetch_and_add(&value->txPackets, packets); \
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__sync_fetch_and_add(&value->txBytes, bytes); \
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} else if (direction == BPF_INGRESS) { \
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__sync_fetch_and_add(&value->rxPackets, packets); \
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__sync_fetch_and_add(&value->rxBytes, bytes); \
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} \
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} \
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}
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DEFINE_UPDATE_STATS(app_uid_stats_map, uint32_t)
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DEFINE_UPDATE_STATS(iface_stats_map, uint32_t)
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DEFINE_UPDATE_STATS(stats_map_A, StatsKey)
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DEFINE_UPDATE_STATS(stats_map_B, StatsKey)
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static inline bool skip_owner_match(struct __sk_buff* skb) {
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int offset = -1;
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int ret = 0;
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if (skb->protocol == htons(ETH_P_IP)) {
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offset = IP_PROTO_OFF;
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uint8_t proto, ihl;
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uint8_t flag;
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ret = bpf_skb_load_bytes(skb, offset, &proto, 1);
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if (!ret) {
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if (proto == IPPROTO_ESP) {
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return true;
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} else if (proto == IPPROTO_TCP) {
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ret = bpf_skb_load_bytes(skb, IPPROTO_IHL_OFF, &ihl, 1);
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ihl = ihl & 0x0F;
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ret = bpf_skb_load_bytes(skb, ihl * 4 + TCP_FLAG_OFF, &flag, 1);
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if (ret == 0 && (flag >> RST_OFFSET & 1)) {
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return true;
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}
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}
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}
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} else if (skb->protocol == htons(ETH_P_IPV6)) {
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offset = IPV6_PROTO_OFF;
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uint8_t proto;
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ret = bpf_skb_load_bytes(skb, offset, &proto, 1);
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if (!ret) {
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if (proto == IPPROTO_ESP) {
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return true;
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} else if (proto == IPPROTO_TCP) {
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uint8_t flag;
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ret = bpf_skb_load_bytes(skb, sizeof(struct ipv6hdr) + TCP_FLAG_OFF, &flag, 1);
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if (ret == 0 && (flag >> RST_OFFSET & 1)) {
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return true;
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}
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}
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}
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}
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return false;
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}
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static __always_inline BpfConfig getConfig(uint32_t configKey) {
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uint32_t mapSettingKey = configKey;
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BpfConfig* config = bpf_configuration_map_lookup_elem(&mapSettingKey);
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if (!config) {
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// Couldn't read configuration entry. Assume everything is disabled.
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return DEFAULT_CONFIG;
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}
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return *config;
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}
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static inline int bpf_owner_match(struct __sk_buff* skb, uint32_t uid, int direction) {
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if (skip_owner_match(skb)) return BPF_PASS;
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if (is_system_uid(uid)) return BPF_PASS;
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BpfConfig enabledRules = getConfig(UID_RULES_CONFIGURATION_KEY);
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UidOwnerValue* uidEntry = bpf_uid_owner_map_lookup_elem(&uid);
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uint32_t uidRules = uidEntry ? uidEntry->rule : 0;
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uint32_t allowed_iif = uidEntry ? uidEntry->iif : 0;
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if (enabledRules) {
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if ((enabledRules & DOZABLE_MATCH) && !(uidRules & DOZABLE_MATCH)) {
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return BPF_DROP;
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}
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if ((enabledRules & STANDBY_MATCH) && (uidRules & STANDBY_MATCH)) {
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return BPF_DROP;
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}
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if ((enabledRules & POWERSAVE_MATCH) && !(uidRules & POWERSAVE_MATCH)) {
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return BPF_DROP;
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}
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if ((enabledRules & RESTRICTED_MATCH) && !(uidRules & RESTRICTED_MATCH)) {
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return BPF_DROP;
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}
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if ((enabledRules & LOW_POWER_STANDBY_MATCH) && !(uidRules & LOW_POWER_STANDBY_MATCH)) {
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return BPF_DROP;
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}
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if ((enabledRules & OEM_DENY_1_MATCH) && (uidRules & OEM_DENY_1_MATCH)) {
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return BPF_DROP;
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}
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if ((enabledRules & OEM_DENY_2_MATCH) && (uidRules & OEM_DENY_2_MATCH)) {
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return BPF_DROP;
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}
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if ((enabledRules & OEM_DENY_3_MATCH) && (uidRules & OEM_DENY_3_MATCH)) {
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return BPF_DROP;
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}
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}
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if (direction == BPF_INGRESS && skb->ifindex != 1) {
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if (uidRules & IIF_MATCH) {
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if (allowed_iif && skb->ifindex != allowed_iif) {
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// Drops packets not coming from lo nor the allowed interface
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// allowed interface=0 is a wildcard and does not drop packets
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return BPF_DROP_UNLESS_DNS;
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}
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} else if (uidRules & LOCKDOWN_VPN_MATCH) {
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// Drops packets not coming from lo and rule does not have IIF_MATCH but has
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// LOCKDOWN_VPN_MATCH
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return BPF_DROP_UNLESS_DNS;
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}
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}
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return BPF_PASS;
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}
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static __always_inline inline void update_stats_with_config(struct __sk_buff* skb, int direction,
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StatsKey* key, uint32_t selectedMap) {
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if (selectedMap == SELECT_MAP_A) {
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update_stats_map_A(skb, direction, key);
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} else if (selectedMap == SELECT_MAP_B) {
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update_stats_map_B(skb, direction, key);
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}
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}
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static __always_inline inline int bpf_traffic_account(struct __sk_buff* skb, int direction) {
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uint32_t sock_uid = bpf_get_socket_uid(skb);
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uint64_t cookie = bpf_get_socket_cookie(skb);
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UidTagValue* utag = bpf_cookie_tag_map_lookup_elem(&cookie);
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uint32_t uid, tag;
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if (utag) {
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uid = utag->uid;
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tag = utag->tag;
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} else {
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uid = sock_uid;
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tag = 0;
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}
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// Always allow and never count clat traffic. Only the IPv4 traffic on the stacked
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// interface is accounted for and subject to usage restrictions.
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// TODO: remove sock_uid check once Nat464Xlat javaland adds the socket tag AID_CLAT for clat.
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if (sock_uid == AID_CLAT || uid == AID_CLAT) {
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return BPF_PASS;
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}
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int match = bpf_owner_match(skb, sock_uid, direction);
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if ((direction == BPF_EGRESS) && (match == BPF_DROP)) {
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// If an outbound packet is going to be dropped, we do not count that
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// traffic.
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return match;
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}
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// Workaround for secureVPN with VpnIsolation enabled, refer to b/159994981 for details.
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// Keep TAG_SYSTEM_DNS in sync with DnsResolver/include/netd_resolv/resolv.h
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// and TrafficStatsConstants.java
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#define TAG_SYSTEM_DNS 0xFFFFFF82
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if (tag == TAG_SYSTEM_DNS && uid == AID_DNS) {
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uid = sock_uid;
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if (match == BPF_DROP_UNLESS_DNS) match = BPF_PASS;
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} else {
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if (match == BPF_DROP_UNLESS_DNS) match = BPF_DROP;
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}
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StatsKey key = {.uid = uid, .tag = tag, .counterSet = 0, .ifaceIndex = skb->ifindex};
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uint8_t* counterSet = bpf_uid_counterset_map_lookup_elem(&uid);
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if (counterSet) key.counterSet = (uint32_t)*counterSet;
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uint32_t mapSettingKey = CURRENT_STATS_MAP_CONFIGURATION_KEY;
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uint32_t* selectedMap = bpf_configuration_map_lookup_elem(&mapSettingKey);
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// Use asm("%0 &= 1" : "+r"(match)) before return match,
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// to help kernel's bpf verifier, so that it can be 100% certain
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// that the returned value is always BPF_NOMATCH(0) or BPF_MATCH(1).
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if (!selectedMap) {
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asm("%0 &= 1" : "+r"(match));
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return match;
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}
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if (key.tag) {
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update_stats_with_config(skb, direction, &key, *selectedMap);
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key.tag = 0;
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}
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update_stats_with_config(skb, direction, &key, *selectedMap);
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update_app_uid_stats_map(skb, direction, &uid);
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asm("%0 &= 1" : "+r"(match));
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return match;
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}
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DEFINE_NETD_BPF_PROG("cgroupskb/ingress/stats", AID_ROOT, AID_SYSTEM, bpf_cgroup_ingress)
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(struct __sk_buff* skb) {
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return bpf_traffic_account(skb, BPF_INGRESS);
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}
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DEFINE_NETD_BPF_PROG("cgroupskb/egress/stats", AID_ROOT, AID_SYSTEM, bpf_cgroup_egress)
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(struct __sk_buff* skb) {
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return bpf_traffic_account(skb, BPF_EGRESS);
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}
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// WARNING: Android T's non-updatable netd depends on the name of this program.
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DEFINE_XTBPF_PROG("skfilter/egress/xtbpf", AID_ROOT, AID_NET_ADMIN, xt_bpf_egress_prog)
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(struct __sk_buff* skb) {
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// Clat daemon does not generate new traffic, all its traffic is accounted for already
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// on the v4-* interfaces (except for the 20 (or 28) extra bytes of IPv6 vs IPv4 overhead,
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// but that can be corrected for later when merging v4-foo stats into interface foo's).
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// TODO: remove sock_uid check once Nat464Xlat javaland adds the socket tag AID_CLAT for clat.
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uint32_t sock_uid = bpf_get_socket_uid(skb);
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if (sock_uid == AID_CLAT) return BPF_NOMATCH;
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if (sock_uid == AID_SYSTEM) {
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uint64_t cookie = bpf_get_socket_cookie(skb);
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UidTagValue* utag = bpf_cookie_tag_map_lookup_elem(&cookie);
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if (utag && utag->uid == AID_CLAT) return BPF_NOMATCH;
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}
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uint32_t key = skb->ifindex;
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update_iface_stats_map(skb, BPF_EGRESS, &key);
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return BPF_MATCH;
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}
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// WARNING: Android T's non-updatable netd depends on the name of this program.
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DEFINE_XTBPF_PROG("skfilter/ingress/xtbpf", AID_ROOT, AID_NET_ADMIN, xt_bpf_ingress_prog)
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(struct __sk_buff* skb) {
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// Clat daemon traffic is not accounted by virtue of iptables raw prerouting drop rule
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// (in clat_raw_PREROUTING chain), which triggers before this (in bw_raw_PREROUTING chain).
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// It will be accounted for on the v4-* clat interface instead.
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// Keep that in mind when moving this out of iptables xt_bpf and into tc ingress (or xdp).
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uint32_t key = skb->ifindex;
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update_iface_stats_map(skb, BPF_INGRESS, &key);
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return BPF_MATCH;
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}
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DEFINE_SYS_BPF_PROG("schedact/ingress/account", AID_ROOT, AID_NET_ADMIN,
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tc_bpf_ingress_account_prog)
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(struct __sk_buff* skb) {
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if (is_received_skb(skb)) {
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// Account for ingress traffic before tc drops it.
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uint32_t key = skb->ifindex;
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update_iface_stats_map(skb, BPF_INGRESS, &key);
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}
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return TC_ACT_UNSPEC;
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}
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|
|
|
// 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_BPF_PROG_EXT("cgroupsock/inet/create", AID_ROOT, AID_ROOT, inet_socket_create,
|
|
KVER(4, 14, 0), KVER_INF, false, "fs_bpf_netd_readonly", "")
|
|
(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");
|