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Rename dscp_policy.o to dscpPolicy.o

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Underscore character may cause bpf prog/map naming collision. For
example, x.o with map y_z and x_y.o with map z both result in x_y_z
prog/map name, which should be prevented during compile-time.

aosp/2147825 will prohibit underscore character in bpf source name
(source name derives the obj name). Existing bpf modules with underscore
characters in source name need to be updated accordingly.

Bug: 236706995
Test: atest bpf_existence_test
Test: adb root; adb shell ls -l sys/fs/bpf/net_shared | grep dscpPolicy
Change-Id: Ibe98944d09d42bd11b78b5e9ae35ded48c70416d
This commit is contained in:
Ken Chen
2022-07-14 16:46:39 +08:00
parent e8bc257597
commit 74ff3ee501
6 changed files with 18 additions and 18 deletions
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319
bpf_progs/dscpPolicy.c Normal file
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@@ -0,0 +1,319 @@
/*
* Copyright (C) 2021 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 <linux/bpf.h>
#include <linux/if_ether.h>
#include <linux/if_packet.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/pkt_cls.h>
#include <linux/tcp.h>
#include <linux/types.h>
#include <netinet/in.h>
#include <netinet/udp.h>
#include <stdint.h>
#include <string.h>
// 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 "dscpPolicy.h"
#define ECN_MASK 3
#define IP4_OFFSET(field, header) (header + offsetof(struct iphdr, field))
#define UPDATE_TOS(dscp, tos) (dscp << 2) | (tos & ECN_MASK)
#define UPDATE_PRIORITY(dscp) ((dscp >> 2) + 0x60)
#define UPDATE_FLOW_LABEL(dscp, flow_lbl) ((dscp & 0xf) << 6) + (flow_lbl >> 6)
DEFINE_BPF_MAP_GRW(switch_comp_map, ARRAY, int, uint64_t, 1, AID_SYSTEM)
DEFINE_BPF_MAP_GRW(ipv4_socket_to_policies_map_A, HASH, uint64_t, RuleEntry, MAX_POLICIES,
AID_SYSTEM)
DEFINE_BPF_MAP_GRW(ipv4_socket_to_policies_map_B, HASH, uint64_t, RuleEntry, MAX_POLICIES,
AID_SYSTEM)
DEFINE_BPF_MAP_GRW(ipv6_socket_to_policies_map_A, HASH, uint64_t, RuleEntry, MAX_POLICIES,
AID_SYSTEM)
DEFINE_BPF_MAP_GRW(ipv6_socket_to_policies_map_B, HASH, uint64_t, RuleEntry, MAX_POLICIES,
AID_SYSTEM)
DEFINE_BPF_MAP_GRW(ipv4_dscp_policies_map, ARRAY, uint32_t, DscpPolicy, MAX_POLICIES, AID_SYSTEM)
DEFINE_BPF_MAP_GRW(ipv6_dscp_policies_map, ARRAY, uint32_t, DscpPolicy, MAX_POLICIES, AID_SYSTEM)
static inline __always_inline void match_policy(struct __sk_buff* skb, bool ipv4, bool is_eth) {
void* data = (void*)(long)skb->data;
const void* data_end = (void*)(long)skb->data_end;
const int l2_header_size = is_eth ? sizeof(struct ethhdr) : 0;
struct ethhdr* eth = is_eth ? data : NULL;
if (data + l2_header_size > data_end) return;
int zero = 0;
int hdr_size = 0;
uint64_t* selected_map = bpf_switch_comp_map_lookup_elem(&zero);
// use this with HASH map so map lookup only happens once policies have been added?
if (!selected_map) {
return;
}
// used for map lookup
uint64_t cookie = bpf_get_socket_cookie(skb);
if (!cookie) return;
uint16_t sport = 0;
uint16_t dport = 0;
uint8_t protocol = 0; // TODO: Use are reserved value? Or int (-1) and cast to uint below?
struct in6_addr src_ip = {};
struct in6_addr dst_ip = {};
uint8_t tos = 0; // Only used for IPv4
uint8_t priority = 0; // Only used for IPv6
uint8_t flow_lbl = 0; // Only used for IPv6
if (ipv4) {
const struct iphdr* const iph = is_eth ? (void*)(eth + 1) : data;
hdr_size = l2_header_size + sizeof(struct iphdr);
// Must have ipv4 header
if (data + hdr_size > data_end) return;
// IP version must be 4
if (iph->version != 4) return;
// We cannot handle IP options, just standard 20 byte == 5 dword minimal IPv4 header
if (iph->ihl != 5) return;
// V4 mapped address in in6_addr sets 10/11 position to 0xff.
src_ip.s6_addr32[2] = htonl(0x0000ffff);
dst_ip.s6_addr32[2] = htonl(0x0000ffff);
// Copy IPv4 address into in6_addr for easy comparison below.
src_ip.s6_addr32[3] = iph->saddr;
dst_ip.s6_addr32[3] = iph->daddr;
protocol = iph->protocol;
tos = iph->tos;
} else {
struct ipv6hdr* ip6h = is_eth ? (void*)(eth + 1) : data;
hdr_size = l2_header_size + sizeof(struct ipv6hdr);
// Must have ipv6 header
if (data + hdr_size > data_end) return;
if (ip6h->version != 6) return;
src_ip = ip6h->saddr;
dst_ip = ip6h->daddr;
protocol = ip6h->nexthdr;
priority = ip6h->priority;
flow_lbl = ip6h->flow_lbl[0];
}
switch (protocol) {
case IPPROTO_UDP:
case IPPROTO_UDPLITE: {
struct udphdr* udp;
udp = data + hdr_size;
if ((void*)(udp + 1) > data_end) return;
sport = udp->source;
dport = udp->dest;
} break;
case IPPROTO_TCP: {
struct tcphdr* tcp;
tcp = data + hdr_size;
if ((void*)(tcp + 1) > data_end) return;
sport = tcp->source;
dport = tcp->dest;
} break;
default:
return;
}
RuleEntry* existing_rule;
if (ipv4) {
if (*selected_map == MAP_A) {
existing_rule = bpf_ipv4_socket_to_policies_map_A_lookup_elem(&cookie);
} else {
existing_rule = bpf_ipv4_socket_to_policies_map_B_lookup_elem(&cookie);
}
} else {
if (*selected_map == MAP_A) {
existing_rule = bpf_ipv6_socket_to_policies_map_A_lookup_elem(&cookie);
} else {
existing_rule = bpf_ipv6_socket_to_policies_map_B_lookup_elem(&cookie);
}
}
if (existing_rule && v6_equal(src_ip, existing_rule->src_ip) &&
v6_equal(dst_ip, existing_rule->dst_ip) && skb->ifindex == existing_rule->ifindex &&
ntohs(sport) == htons(existing_rule->src_port) &&
ntohs(dport) == htons(existing_rule->dst_port) && protocol == existing_rule->proto) {
if (ipv4) {
uint8_t newTos = UPDATE_TOS(existing_rule->dscp_val, tos);
bpf_l3_csum_replace(skb, IP4_OFFSET(check, l2_header_size), htons(tos), htons(newTos),
sizeof(uint16_t));
bpf_skb_store_bytes(skb, IP4_OFFSET(tos, l2_header_size), &newTos, sizeof(newTos), 0);
} else {
uint8_t new_priority = UPDATE_PRIORITY(existing_rule->dscp_val);
uint8_t new_flow_label = UPDATE_FLOW_LABEL(existing_rule->dscp_val, flow_lbl);
bpf_skb_store_bytes(skb, 0 + l2_header_size, &new_priority, sizeof(uint8_t), 0);
bpf_skb_store_bytes(skb, 1 + l2_header_size, &new_flow_label, sizeof(uint8_t), 0);
}
return;
}
// Linear scan ipv4_dscp_policies_map since no stored params match skb.
int best_score = -1;
uint32_t best_match = 0;
for (register uint64_t i = 0; i < MAX_POLICIES; i++) {
int score = 0;
uint8_t temp_mask = 0;
// Using a uint64 in for loop prevents infinite loop during BPF load,
// but the key is uint32, so convert back.
uint32_t key = i;
DscpPolicy* policy;
if (ipv4) {
policy = bpf_ipv4_dscp_policies_map_lookup_elem(&key);
} else {
policy = bpf_ipv6_dscp_policies_map_lookup_elem(&key);
}
// If the policy lookup failed, present_fields is 0, or iface index does not match
// index on skb buff, then we can continue to next policy.
if (!policy || policy->present_fields == 0 || policy->ifindex != skb->ifindex) continue;
if ((policy->present_fields & SRC_IP_MASK_FLAG) == SRC_IP_MASK_FLAG &&
v6_equal(src_ip, policy->src_ip)) {
score++;
temp_mask |= SRC_IP_MASK_FLAG;
}
if ((policy->present_fields & DST_IP_MASK_FLAG) == DST_IP_MASK_FLAG &&
v6_equal(dst_ip, policy->dst_ip)) {
score++;
temp_mask |= DST_IP_MASK_FLAG;
}
if ((policy->present_fields & SRC_PORT_MASK_FLAG) == SRC_PORT_MASK_FLAG &&
ntohs(sport) == htons(policy->src_port)) {
score++;
temp_mask |= SRC_PORT_MASK_FLAG;
}
if ((policy->present_fields & DST_PORT_MASK_FLAG) == DST_PORT_MASK_FLAG &&
ntohs(dport) >= htons(policy->dst_port_start) &&
ntohs(dport) <= htons(policy->dst_port_end)) {
score++;
temp_mask |= DST_PORT_MASK_FLAG;
}
if ((policy->present_fields & PROTO_MASK_FLAG) == PROTO_MASK_FLAG &&
protocol == policy->proto) {
score++;
temp_mask |= PROTO_MASK_FLAG;
}
if (score > best_score && temp_mask == policy->present_fields) {
best_match = i;
best_score = score;
}
}
uint8_t new_tos = 0; // Can 0 be used as default forwarding value?
uint8_t new_dscp = 0;
uint8_t new_priority = 0;
uint8_t new_flow_lbl = 0;
if (best_score > 0) {
DscpPolicy* policy;
if (ipv4) {
policy = bpf_ipv4_dscp_policies_map_lookup_elem(&best_match);
} else {
policy = bpf_ipv6_dscp_policies_map_lookup_elem(&best_match);
}
if (policy) {
new_dscp = policy->dscp_val;
if (ipv4) {
new_tos = UPDATE_TOS(new_dscp, tos);
} else {
new_priority = UPDATE_PRIORITY(new_dscp);
new_flow_lbl = UPDATE_FLOW_LABEL(new_dscp, flow_lbl);
}
}
} else
return;
RuleEntry value = {
.src_ip = src_ip,
.dst_ip = dst_ip,
.ifindex = skb->ifindex,
.src_port = sport,
.dst_port = dport,
.proto = protocol,
.dscp_val = new_dscp,
};
// Update map with new policy.
if (ipv4) {
if (*selected_map == MAP_A) {
bpf_ipv4_socket_to_policies_map_A_update_elem(&cookie, &value, BPF_ANY);
} else {
bpf_ipv4_socket_to_policies_map_B_update_elem(&cookie, &value, BPF_ANY);
}
} else {
if (*selected_map == MAP_A) {
bpf_ipv6_socket_to_policies_map_A_update_elem(&cookie, &value, BPF_ANY);
} else {
bpf_ipv6_socket_to_policies_map_B_update_elem(&cookie, &value, BPF_ANY);
}
}
// Need to store bytes after updating map or program will not load.
if (ipv4 && new_tos != (tos & 252)) {
bpf_l3_csum_replace(skb, IP4_OFFSET(check, l2_header_size), htons(tos), htons(new_tos), 2);
bpf_skb_store_bytes(skb, IP4_OFFSET(tos, l2_header_size), &new_tos, sizeof(new_tos), 0);
} else if (!ipv4 && (new_priority != priority || new_flow_lbl != flow_lbl)) {
bpf_skb_store_bytes(skb, l2_header_size, &new_priority, sizeof(new_priority), 0);
bpf_skb_store_bytes(skb, l2_header_size + 1, &new_flow_lbl, sizeof(new_flow_lbl), 0);
}
return;
}
DEFINE_BPF_PROG_KVER("schedcls/set_dscp_ether", AID_ROOT, AID_SYSTEM,
schedcls_set_dscp_ether, KVER(5, 15, 0))
(struct __sk_buff* skb) {
if (skb->pkt_type != PACKET_HOST) return TC_ACT_PIPE;
if (skb->protocol == htons(ETH_P_IP)) {
match_policy(skb, true, true);
} else if (skb->protocol == htons(ETH_P_IPV6)) {
match_policy(skb, false, true);
}
// Always return TC_ACT_PIPE
return TC_ACT_PIPE;
}
DEFINE_BPF_PROG_KVER("schedcls/set_dscp_raw_ip", AID_ROOT, AID_SYSTEM,
schedcls_set_dscp_raw_ip, KVER(5, 15, 0))
(struct __sk_buff* skb) {
if (skb->protocol == htons(ETH_P_IP)) {
match_policy(skb, true, false);
} else if (skb->protocol == htons(ETH_P_IPV6)) {
match_policy(skb, false, false);
}
// Always return TC_ACT_PIPE
return TC_ACT_PIPE;
}
LICENSE("Apache 2.0");
CRITICAL("Connectivity");