| /* |
| * Copyright (C) 2020 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 |
| |
| /* This file is separate because it's included both by eBPF programs (via include |
| * in bpf_helpers.h) and directly by the boot time bpfloader (Loader.cpp). |
| */ |
| |
| #include <linux/bpf.h> |
| |
| // Pull in AID_* constants from //system/core/libcutils/include/private/android_filesystem_config.h |
| #include <cutils/android_filesystem_config.h> |
| |
| /****************************************************************************** |
| * * |
| * ! ! ! W A R N I N G ! ! ! * |
| * * |
| * CHANGES TO THESE STRUCTURE DEFINITIONS OUTSIDE OF AOSP/MASTER *WILL* BREAK * |
| * MAINLINE MODULE COMPATIBILITY * |
| * * |
| * AND THUS MAY RESULT IN YOUR DEVICE BRICKING AT SOME ARBITRARY POINT IN * |
| * THE FUTURE * |
| * * |
| * (and even in aosp/master you may only append new fields at the very end, * |
| * you may *never* delete fields, change their types, ordering, insert in * |
| * the middle, etc. If a mainline module using the old definition has * |
| * already shipped (which happens roughly monthly), then it's set in stone) * |
| * * |
| ******************************************************************************/ |
| |
| // These are the values used if these fields are missing |
| #define DEFAULT_BPFLOADER_MIN_VER 0u // v0.0 (this is inclusive ie. >= v0.0) |
| #define DEFAULT_BPFLOADER_MAX_VER 0x10000u // v1.0 (this is exclusive ie. < v1.0) |
| #define DEFAULT_SIZEOF_BPF_MAP_DEF 32 // v0.0 struct: enum (uint sized) + 7 uint |
| #define DEFAULT_SIZEOF_BPF_PROG_DEF 20 // v0.0 struct: 4 uint + bool + 3 byte alignment pad |
| |
| // By default, unless otherwise specified, allow the use of features only supported by v0.37. |
| #define COMPILE_FOR_BPFLOADER_VERSION 37u |
| |
| /* |
| * The bpf_{map,prog}_def structures are compiled for different architectures. |
| * Once by the BPF compiler for the BPF architecture, and once by a C++ |
| * compiler for the native Android architecture for the bpfloader. |
| * |
| * For things to work, their layout must be the same between the two. |
| * The BPF architecture is platform independent ('64-bit LSB bpf'). |
| * So this effectively means these structures must be the same layout |
| * on 5 architectures, all of them little endian: |
| * 64-bit BPF, x86_64, arm and 32-bit x86 and arm |
| * |
| * As such for any types we use inside of these structs we must make sure that |
| * the size and alignment are the same, so the same amount of padding is used. |
| * |
| * Currently we only use: bool, enum bpf_map_type and unsigned int. |
| * Additionally we use char for padding. |
| * |
| * !!! WARNING: HERE BE DRAGONS !!! |
| * |
| * Be particularly careful with 64-bit integers. |
| * You will need to manually override their alignment to 8 bytes. |
| * |
| * To quote some parts of https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69560 |
| * |
| * Some types have weaker alignment requirements when they are structure members. |
| * |
| * unsigned long long on x86 is such a type. |
| * |
| * C distinguishes C11 _Alignof (the minimum alignment the type is guaranteed |
| * to have in all contexts, so 4, see min_align_of_type) from GNU C __alignof |
| * (the normal alignment of the type, so 8). |
| * |
| * alignof / _Alignof == minimum alignment required by target ABI |
| * __alignof / __alignof__ == preferred alignment |
| * |
| * When in a struct, apparently the minimum alignment is used. |
| */ |
| |
| _Static_assert(sizeof(bool) == 1, "sizeof bool != 1"); |
| _Static_assert(__alignof__(bool) == 1, "__alignof__ bool != 1"); |
| _Static_assert(_Alignof(bool) == 1, "_Alignof bool != 1"); |
| |
| _Static_assert(sizeof(char) == 1, "sizeof char != 1"); |
| _Static_assert(__alignof__(char) == 1, "__alignof__ char != 1"); |
| _Static_assert(_Alignof(char) == 1, "_Alignof char != 1"); |
| |
| // This basically verifies that an enum is 'just' a 32-bit int |
| _Static_assert(sizeof(enum bpf_map_type) == 4, "sizeof enum bpf_map_type != 4"); |
| _Static_assert(__alignof__(enum bpf_map_type) == 4, "__alignof__ enum bpf_map_type != 4"); |
| _Static_assert(_Alignof(enum bpf_map_type) == 4, "_Alignof enum bpf_map_type != 4"); |
| |
| // Linux kernel requires sizeof(int) == 4, sizeof(void*) == sizeof(long), sizeof(long long) == 8 |
| _Static_assert(sizeof(unsigned int) == 4, "sizeof unsigned int != 4"); |
| _Static_assert(__alignof__(unsigned int) == 4, "__alignof__ unsigned int != 4"); |
| _Static_assert(_Alignof(unsigned int) == 4, "_Alignof unsigned int != 4"); |
| |
| // We don't currently use any 64-bit types in these structs, so this is purely to document issue. |
| // Here sizeof & __alignof__ are consistent, but _Alignof is not: compile for 'aosp_cf_x86_phone' |
| _Static_assert(sizeof(unsigned long long) == 8, "sizeof unsigned long long != 8"); |
| _Static_assert(__alignof__(unsigned long long) == 8, "__alignof__ unsigned long long != 8"); |
| // BPF wants 8, but 32-bit x86 wants 4 |
| //_Static_assert(_Alignof(unsigned long long) == 8, "_Alignof unsigned long long != 8"); |
| |
| // Length of strings (incl. selinux_context and pin_subdir) |
| // in the bpf_map_def and bpf_prog_def structs. |
| // |
| // WARNING: YOU CANNOT *EVER* CHANGE THESE |
| // as this would affect the structure size in backwards incompatible ways |
| // and break mainline module loading on older Android T devices |
| #define BPF_SELINUX_CONTEXT_CHAR_ARRAY_SIZE 32 |
| #define BPF_PIN_SUBDIR_CHAR_ARRAY_SIZE 32 |
| |
| /* |
| * Map structure to be used by Android eBPF C programs. The Android eBPF loader |
| * uses this structure from eBPF object to create maps at boot time. |
| * |
| * The eBPF C program should define structure in the maps section using |
| * SECTION("maps") otherwise it will be ignored by the eBPF loader. |
| * |
| * For example: |
| * const struct bpf_map_def SECTION("maps") mymap { .type=... , .key_size=... } |
| * |
| * See 'bpf_helpers.h' for helpful macros for eBPF program use. |
| */ |
| struct bpf_map_def { |
| enum bpf_map_type type; |
| unsigned int key_size; |
| unsigned int value_size; |
| unsigned int max_entries; |
| unsigned int map_flags; |
| |
| // The following are not supported by the Android bpfloader: |
| // unsigned int inner_map_idx; |
| // unsigned int numa_node; |
| |
| unsigned int zero; // uid_t, for compat with old (buggy) bpfloader must be AID_ROOT == 0 |
| unsigned int gid; // gid_t |
| unsigned int mode; // mode_t |
| |
| // The following fields were added in version 0.1 |
| unsigned int bpfloader_min_ver; // if missing, defaults to 0, ie. v0.0 |
| unsigned int bpfloader_max_ver; // if missing, defaults to 0x10000, ie. v1.0 |
| |
| // The following fields were added in version 0.2 (S) |
| // kernelVersion() must be >= min_kver and < max_kver |
| unsigned int min_kver; |
| unsigned int max_kver; |
| |
| // The following fields were added in version 0.18 (T) |
| // |
| // These are fixed length strings, padded with null bytes |
| // |
| // Warning: supported values depend on .o location |
| // (additionally a newer Android OS and/or bpfloader may support more values) |
| // |
| // overrides default selinux context (which is based on pin subdir) |
| char selinux_context[BPF_SELINUX_CONTEXT_CHAR_ARRAY_SIZE]; |
| // |
| // overrides default prefix (which is based on .o location) |
| char pin_subdir[BPF_PIN_SUBDIR_CHAR_ARRAY_SIZE]; |
| |
| bool shared; // use empty string as 'file' component of pin path - allows cross .o map sharing |
| |
| // The following 3 ignore_on_* fields were added in version 0.32 (U). These are ignored in |
| // older bpfloader versions, and zero in programs compiled before 0.32. |
| bool ignore_on_eng:1; |
| bool ignore_on_user:1; |
| bool ignore_on_userdebug:1; |
| // The following 5 ignore_on_* fields were added in version 0.38 (U). These are ignored in |
| // older bpfloader versions, and zero in programs compiled before 0.38. |
| // These are tests on the kernel architecture, ie. they ignore userspace bit-ness. |
| bool ignore_on_arm32:1; |
| bool ignore_on_aarch64:1; |
| bool ignore_on_x86_32:1; |
| bool ignore_on_x86_64:1; |
| bool ignore_on_riscv64:1; |
| |
| char pad0[2]; // manually pad up to 4 byte alignment, may be used for extensions in the future |
| |
| unsigned int uid; // uid_t |
| }; |
| |
| _Static_assert(sizeof(((struct bpf_map_def *)0)->selinux_context) == 32, "must be 32 bytes"); |
| _Static_assert(sizeof(((struct bpf_map_def *)0)->pin_subdir) == 32, "must be 32 bytes"); |
| |
| // This needs to be updated whenever the above structure definition is expanded. |
| _Static_assert(sizeof(struct bpf_map_def) == 120, "sizeof struct bpf_map_def != 120"); |
| _Static_assert(__alignof__(struct bpf_map_def) == 4, "__alignof__ struct bpf_map_def != 4"); |
| _Static_assert(_Alignof(struct bpf_map_def) == 4, "_Alignof struct bpf_map_def != 4"); |
| |
| struct bpf_prog_def { |
| unsigned int uid; |
| unsigned int gid; |
| |
| // kernelVersion() must be >= min_kver and < max_kver |
| unsigned int min_kver; |
| unsigned int max_kver; |
| |
| bool optional; // program section (ie. function) may fail to load, continue onto next func. |
| |
| // The following 3 ignore_on_* fields were added in version 0.33 (U). These are ignored in |
| // older bpfloader versions, and zero in programs compiled before 0.33. |
| bool ignore_on_eng:1; |
| bool ignore_on_user:1; |
| bool ignore_on_userdebug:1; |
| // The following 5 ignore_on_* fields were added in version 0.38 (U). These are ignored in |
| // older bpfloader versions, and zero in programs compiled before 0.38. |
| // These are tests on the kernel architecture, ie. they ignore userspace bit-ness. |
| bool ignore_on_arm32:1; |
| bool ignore_on_aarch64:1; |
| bool ignore_on_x86_32:1; |
| bool ignore_on_x86_64:1; |
| bool ignore_on_riscv64:1; |
| |
| char pad0[2]; // manually pad up to 4 byte alignment, may be used for extensions in the future |
| |
| // The following fields were added in version 0.1 |
| unsigned int bpfloader_min_ver; // if missing, defaults to 0, ie. v0.0 |
| unsigned int bpfloader_max_ver; // if missing, defaults to 0x10000, ie. v1.0 |
| |
| // The following fields were added in version 0.18, see description up above in bpf_map_def |
| char selinux_context[BPF_SELINUX_CONTEXT_CHAR_ARRAY_SIZE]; |
| char pin_subdir[BPF_PIN_SUBDIR_CHAR_ARRAY_SIZE]; |
| }; |
| |
| _Static_assert(sizeof(((struct bpf_prog_def *)0)->selinux_context) == 32, "must be 32 bytes"); |
| _Static_assert(sizeof(((struct bpf_prog_def *)0)->pin_subdir) == 32, "must be 32 bytes"); |
| |
| // This needs to be updated whenever the above structure definition is expanded. |
| _Static_assert(sizeof(struct bpf_prog_def) == 92, "sizeof struct bpf_prog_def != 92"); |
| _Static_assert(__alignof__(struct bpf_prog_def) == 4, "__alignof__ struct bpf_prog_def != 4"); |
| _Static_assert(_Alignof(struct bpf_prog_def) == 4, "_Alignof struct bpf_prog_def != 4"); |
