bpf_progs/netd.h

/*
 * 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.
 */

#pragma once

#include <cutils/android_filesystem_config.h>
#include <linux/if.h>
#include <linux/if_ether.h>
#include <linux/in.h>
#include <linux/in6.h>

#ifdef __cplusplus
#include <string_view>
#include "XtBpfProgLocations.h"
#endif

// This header file is shared by eBPF kernel programs (C) and netd (C++) and
// some of the maps are also accessed directly from Java mainline module code.
//
// Hence: explicitly pad all relevant structures and assert that their size
// is the sum of the sizes of their fields.
#define STRUCT_SIZE(name, size) _Static_assert(sizeof(name) == (size), "Incorrect struct size.")

typedef struct {
    uint32_t uid;
    uint32_t tag;
} UidTagValue;
STRUCT_SIZE(UidTagValue, 2 * 4);  // 8

typedef struct {
    uint32_t uid;
    uint32_t tag;
    uint32_t counterSet;
    uint32_t ifaceIndex;
} StatsKey;
STRUCT_SIZE(StatsKey, 4 * 4);  // 16

typedef struct {
    uint64_t rxPackets;
    uint64_t rxBytes;
    uint64_t txPackets;
    uint64_t txBytes;
} StatsValue;
STRUCT_SIZE(StatsValue, 4 * 8);  // 32

#ifdef __cplusplus
static inline StatsValue& operator+=(StatsValue& lhs, const StatsValue& rhs) {
    lhs.rxPackets += rhs.rxPackets;
    lhs.rxBytes += rhs.rxBytes;
    lhs.txPackets += rhs.txPackets;
    lhs.txBytes += rhs.txBytes;
    return lhs;
}
#endif

typedef struct {
    char name[IFNAMSIZ];
} IfaceValue;
STRUCT_SIZE(IfaceValue, 16);

typedef struct {
  uint64_t timestampNs;
  uint32_t ifindex;
  uint32_t length;

  uint32_t uid;
  uint32_t tag;

  __be16 sport;
  __be16 dport;

  bool egress:1,
       wakeup:1;
  uint8_t ipProto;
  uint8_t tcpFlags;
  uint8_t ipVersion; // 4=IPv4, 6=IPv6, 0=unknown
} PacketTrace;
STRUCT_SIZE(PacketTrace, 8+4+4 + 4+4 + 2+2 + 1+1+1+1);

// Since we cannot garbage collect the stats map since device boot, we need to make these maps as
// large as possible. The maximum size of number of map entries we can have is depend on the rlimit
// of MEM_LOCK granted to netd. The memory space needed by each map can be calculated by the
// following fomula:
//      elem_size = 40 + roundup(key_size, 8) + roundup(value_size, 8)
//      cost = roundup_pow_of_two(max_entries) * 16 + elem_size * max_entries +
//              elem_size * number_of_CPU
// And the cost of each map currently used is(assume the device have 8 CPUs):
// cookie_tag_map:      key:  8 bytes, value:  8 bytes, cost:  822592 bytes    =   823Kbytes
// uid_counter_set_map: key:  4 bytes, value:  1 bytes, cost:  145216 bytes    =   145Kbytes
// app_uid_stats_map:   key:  4 bytes, value: 32 bytes, cost: 1062784 bytes    =  1063Kbytes
// uid_stats_map:       key: 16 bytes, value: 32 bytes, cost: 1142848 bytes    =  1143Kbytes
// tag_stats_map:       key: 16 bytes, value: 32 bytes, cost: 1142848 bytes    =  1143Kbytes
// iface_index_name_map:key:  4 bytes, value: 16 bytes, cost:   80896 bytes    =    81Kbytes
// iface_stats_map:     key:  4 bytes, value: 32 bytes, cost:   97024 bytes    =    97Kbytes
// dozable_uid_map:     key:  4 bytes, value:  1 bytes, cost:  145216 bytes    =   145Kbytes
// standby_uid_map:     key:  4 bytes, value:  1 bytes, cost:  145216 bytes    =   145Kbytes
// powersave_uid_map:   key:  4 bytes, value:  1 bytes, cost:  145216 bytes    =   145Kbytes
// packet_trace_ringbuf:key:  0 bytes, value: 24 bytes, cost:   32768 bytes    =    32Kbytes
// total:                                                                         4962Kbytes
// It takes maximum 4.9MB kernel memory space if all maps are full, which requires any devices
// running this module to have a memlock rlimit to be larger then 5MB. In the old qtaguid module,
// we don't have a total limit for data entries but only have limitation of tags each uid can have.
// (default is 1024 in kernel);

// 'static' - otherwise these constants end up in .rodata in the resulting .o post compilation
static const int COOKIE_UID_MAP_SIZE = 10000;
static const int UID_COUNTERSET_MAP_SIZE = 4000;
static const int APP_STATS_MAP_SIZE = 10000;
static const int STATS_MAP_SIZE = 5000;
static const int IFACE_INDEX_NAME_MAP_SIZE = 1000;
static const int IFACE_STATS_MAP_SIZE = 1000;
static const int CONFIGURATION_MAP_SIZE = 2;
static const int UID_OWNER_MAP_SIZE = 4000;
static const int INGRESS_DISCARD_MAP_SIZE = 100;
static const int PACKET_TRACE_BUF_SIZE = 32 * 1024;
static const int DATA_SAVER_ENABLED_MAP_SIZE = 1;

#ifdef __cplusplus

#define BPF_NETD_PATH "/sys/fs/bpf/netd_shared/"

#define BPF_EGRESS_PROG_PATH BPF_NETD_PATH "prog_netd_cgroupskb_egress_stats"
#define BPF_INGRESS_PROG_PATH BPF_NETD_PATH "prog_netd_cgroupskb_ingress_stats"

#define ASSERT_STRING_EQUAL(s1, s2) \
    static_assert(std::string_view(s1) == std::string_view(s2), "mismatch vs Android T netd")

/* -=-=-=-=- WARNING -=-=-=-=-
 *
 * These 4 xt_bpf program paths are actually defined by:
 *   //system/netd/include/mainline/XtBpfProgLocations.h
 * which is intentionally a non-automerged location.
 *
 * They are *UNCHANGEABLE* due to being hard coded in Android T's netd binary
 * as such we have compile time asserts that things match.
 * (which will be validated during build on mainline-prod branch against old system/netd)
 *
 * If you break this, netd on T will fail to start with your tethering mainline module.
 */
ASSERT_STRING_EQUAL(XT_BPF_INGRESS_PROG_PATH,   BPF_NETD_PATH "prog_netd_skfilter_ingress_xtbpf");
ASSERT_STRING_EQUAL(XT_BPF_EGRESS_PROG_PATH,    BPF_NETD_PATH "prog_netd_skfilter_egress_xtbpf");
ASSERT_STRING_EQUAL(XT_BPF_ALLOWLIST_PROG_PATH, BPF_NETD_PATH "prog_netd_skfilter_allowlist_xtbpf");
ASSERT_STRING_EQUAL(XT_BPF_DENYLIST_PROG_PATH,  BPF_NETD_PATH "prog_netd_skfilter_denylist_xtbpf");

#define CGROUP_SOCKET_PROG_PATH BPF_NETD_PATH "prog_netd_cgroupsock_inet_create"

#define TC_BPF_INGRESS_ACCOUNT_PROG_NAME "prog_netd_schedact_ingress_account"
#define TC_BPF_INGRESS_ACCOUNT_PROG_PATH BPF_NETD_PATH TC_BPF_INGRESS_ACCOUNT_PROG_NAME

#define COOKIE_TAG_MAP_PATH BPF_NETD_PATH "map_netd_cookie_tag_map"
#define UID_COUNTERSET_MAP_PATH BPF_NETD_PATH "map_netd_uid_counterset_map"
#define APP_UID_STATS_MAP_PATH BPF_NETD_PATH "map_netd_app_uid_stats_map"
#define STATS_MAP_A_PATH BPF_NETD_PATH "map_netd_stats_map_A"
#define STATS_MAP_B_PATH BPF_NETD_PATH "map_netd_stats_map_B"
#define IFACE_INDEX_NAME_MAP_PATH BPF_NETD_PATH "map_netd_iface_index_name_map"
#define IFACE_STATS_MAP_PATH BPF_NETD_PATH "map_netd_iface_stats_map"
#define CONFIGURATION_MAP_PATH BPF_NETD_PATH "map_netd_configuration_map"
#define UID_OWNER_MAP_PATH BPF_NETD_PATH "map_netd_uid_owner_map"
#define UID_PERMISSION_MAP_PATH BPF_NETD_PATH "map_netd_uid_permission_map"
#define INGRESS_DISCARD_MAP_PATH BPF_NETD_PATH "map_netd_ingress_discard_map"
#define PACKET_TRACE_RINGBUF_PATH BPF_NETD_PATH "map_netd_packet_trace_ringbuf"
#define PACKET_TRACE_ENABLED_MAP_PATH BPF_NETD_PATH "map_netd_packet_trace_enabled_map"
#define DATA_SAVER_ENABLED_MAP_PATH BPF_NETD_PATH "map_netd_data_saver_enabled_map"

#endif // __cplusplus

// LINT.IfChange(match_type)
enum UidOwnerMatchType : uint32_t {
    NO_MATCH = 0,
    HAPPY_BOX_MATCH = (1 << 0),
    PENALTY_BOX_MATCH = (1 << 1),
    DOZABLE_MATCH = (1 << 2),
    STANDBY_MATCH = (1 << 3),
    POWERSAVE_MATCH = (1 << 4),
    RESTRICTED_MATCH = (1 << 5),
    LOW_POWER_STANDBY_MATCH = (1 << 6),
    IIF_MATCH = (1 << 7),
    LOCKDOWN_VPN_MATCH = (1 << 8),
    OEM_DENY_1_MATCH = (1 << 9),
    OEM_DENY_2_MATCH = (1 << 10),
    OEM_DENY_3_MATCH = (1 << 11),
    BACKGROUND_MATCH = (1 << 12)
};
// LINT.ThenChange(../framework/src/android/net/BpfNetMapsConstants.java)

enum BpfPermissionMatch : uint8_t {
    BPF_PERMISSION_INTERNET = 1 << 2,
    BPF_PERMISSION_UPDATE_DEVICE_STATS = 1 << 3,
};
// In production we use two identical stats maps to record per uid stats and
// do swap and clean based on the configuration specified here. The statsMapType
// value in configuration map specified which map is currently in use.
enum StatsMapType : uint32_t {
    SELECT_MAP_A,
    SELECT_MAP_B,
};

// TODO: change the configuration object from a bitmask to an object with clearer
// semantics, like a struct.
typedef uint32_t BpfConfig;
static const BpfConfig DEFAULT_CONFIG = 0;

typedef struct {
    // Allowed interface index. Only applicable if IIF_MATCH is set in the rule bitmask above.
    uint32_t iif;
    // A bitmask of enum values in UidOwnerMatchType.
    uint32_t rule;
} UidOwnerValue;
STRUCT_SIZE(UidOwnerValue, 2 * 4);  // 8

typedef struct {
    // The destination ip of the incoming packet.  IPv4 uses IPv4-mapped IPv6 address format.
    struct in6_addr daddr;
} IngressDiscardKey;
STRUCT_SIZE(IngressDiscardKey, 16);  // 16

typedef struct {
    // Allowed interface indexes.  Use same value multiple times if you just want to match 1 value.
    uint32_t iif[2];
} IngressDiscardValue;
STRUCT_SIZE(IngressDiscardValue, 2 * 4);  // 8

// Entry in the configuration map that stores which UID rules are enabled.
#define UID_RULES_CONFIGURATION_KEY 0
// Entry in the configuration map that stores which stats map is currently in use.
#define CURRENT_STATS_MAP_CONFIGURATION_KEY 1
// Entry in the data saver enabled map that stores whether data saver is enabled or not.
#define DATA_SAVER_ENABLED_KEY 0

#undef STRUCT_SIZE

// DROP_IF_SET is set of rules that 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 | BACKGROUND_MATCH)

// 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.  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.
static inline bool isBlockedByUidRules(BpfConfig enabledRules, uint32_t uidRules) {
    return enabledRules & (DROP_IF_SET | DROP_IF_UNSET) & (uidRules ^ DROP_IF_UNSET);
}

static inline bool 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);
}