1 /* 2 * Copyright (C) 2014 The Android Open Source Project 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in 12 * the documentation and/or other materials provided with the 13 * distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #pragma once 30 31 #include <arpa/nameser.h> 32 #include <netinet/in.h> 33 34 /* 35 * Passing NETID_UNSET as the netId causes system/netd/resolv/DnsProxyListener.cpp to 36 * fill in the appropriate default netId for the query. 37 */ 38 #define NETID_UNSET 0u 39 40 /* 41 * MARK_UNSET represents the default (i.e. unset) value for a socket mark. 42 */ 43 #define MARK_UNSET 0u 44 45 #define NET_CONTEXT_INVALID_UID ((uid_t)-1) 46 #define NET_CONTEXT_INVALID_PID ((pid_t)-1) 47 48 /* 49 * A struct to capture context relevant to network operations. 50 * 51 * Application and DNS netids/marks can differ from one another under certain 52 * circumstances, notably when a VPN applies to the given uid's traffic but the 53 * VPN network does not have its own DNS servers explicitly provisioned. 54 * 55 * The introduction of per-UID routing means the uid is also an essential part 56 * of the evaluation context. Its proper uninitialized value is 57 * NET_CONTEXT_INVALID_UID. 58 */ 59 struct android_net_context { 60 unsigned app_netid; 61 unsigned app_mark; 62 unsigned dns_netid; 63 unsigned dns_mark; 64 uid_t uid = NET_CONTEXT_INVALID_UID; 65 unsigned flags; 66 // Variable to store the pid of the application sending DNS query. 67 pid_t pid = NET_CONTEXT_INVALID_PID; 68 }; 69 70 #define NET_CONTEXT_FLAG_USE_LOCAL_NAMESERVERS 0x00000001 71 #define NET_CONTEXT_FLAG_USE_EDNS 0x00000002 72 #define NET_CONTEXT_FLAG_USE_DNS_OVER_TLS 0x00000004 73 74 // TODO: investigate having the resolver check permissions itself, either by adding support to 75 // libbinder_ndk or by converting IPermissionController into a stable AIDL interface. 76 typedef bool (*check_calling_permission_callback)(const char* permission); 77 typedef void (*get_network_context_callback)(unsigned netid, uid_t uid, 78 android_net_context* netcontext); 79 typedef void (*log_callback)(const char* msg); 80 typedef int (*tagSocketCallback)(int sockFd, uint32_t tag, uid_t uid, pid_t pid); 81 82 // The DnsResolver module invokes this callback once before starting each DNS 83 // lookup. The callback receives the android_net_context associated with the 84 // request, and the (possibly unqualified) hostname requested by the app via 85 // getaddrinfo() or gethostbyname(). 86 // 87 // If the callback returns false, the DnsResolver will abort the request 88 // returning EAI_SYSTEM. If the callback returns true, the query will proceed as 89 // usual. 90 // 91 // If this callback is not present (i.e. set to nullptr), the effect is the same 92 // of returning true. 93 // 94 // This callback *will* be invoked concurrently from multiple threads. It must 95 // peform its own locking when accessing shared data structures. Furthermore, 96 // the callback must not sleep nor perform RPC requests. 97 // 98 // Be mindful that hostnames could contain sensitive user data. Do not log them 99 // and do not transmit them to third parties without explicit user 100 // authorization. 101 // 102 typedef bool (*evaluate_domain_name_callback)( 103 const android_net_context &netcontext, const char *host); 104 105 /* 106 * Some functions needed by the resolver (e.g. checkCallingPermission()) live in 107 * libraries with no ABI stability guarantees, such as libbinder.so. 108 * As a temporary workaround, we keep these functions in netd and call them via 109 * function pointers. 110 */ 111 struct ResolverNetdCallbacks { 112 check_calling_permission_callback check_calling_permission; 113 get_network_context_callback get_network_context; 114 log_callback log; 115 tagSocketCallback tagSocket; 116 evaluate_domain_name_callback evaluate_domain_name; 117 }; 118 119 #define TAG_SYSTEM_DNS 0xFFFFFF82 120 121 #define LIBNETD_RESOLV_PUBLIC extern "C" [[gnu::visibility("default")]] 122 123 LIBNETD_RESOLV_PUBLIC bool resolv_has_nameservers(unsigned netid); 124 125 // Set callbacks and bring DnsResolver up. 126 LIBNETD_RESOLV_PUBLIC bool resolv_init(const ResolverNetdCallbacks* callbacks); 127 128 // Function that performs RDNS in local cache. The |domain_name_size| is the size of domain_name 129 // buffer, which is recommended to NS_MAXDNAME. Function return false if hostname not found or 130 // domain_name_size > NS_MAXDNAME. 131 LIBNETD_RESOLV_PUBLIC bool resolv_gethostbyaddr_from_cache(unsigned netId, char domain_name[], 132 size_t domain_name_size, 133 const char* ip_address, int af); 134