/* Common BPF helpers to be used by all BPF programs loaded by Android */ #include #include #include #include "bpf_map_def.h" /****************************************************************************** * WARNING: CHANGES TO THIS FILE OUTSIDE OF AOSP/MASTER ARE LIKELY TO BREAK * * DEVICE COMPATIBILITY WITH MAINLINE MODULES SHIPPING EBPF CODE. * * * * THIS WILL LIKELY RESULT IN BRICKED DEVICES AT SOME ARBITRARY FUTURE TIME * * * * THAT GOES ESPECIALLY FOR THE 'SECTION' 'LICENSE' AND 'CRITICAL' MACROS * * * * We strongly suggest that if you need changes to bpfloader functionality * * you get your changes reviewed and accepted into aosp/master. * * * ******************************************************************************/ // The actual versions of the bpfloader that shipped in various Android releases // Android P/Q/R: BpfLoader was initially part of netd, // this was later split out into a standalone binary, but was unversioned. // Android S / 12 (api level 31) - added 'tethering' mainline eBPF support #define BPFLOADER_S_VERSION 2u // Android T / 13 Beta 3 (api level 33) - added support for 'netd_shared' #define BPFLOADER_T_BETA3_VERSION 13u // v0.18 added support for shared and pindir, but still ignores selinux_content // v0.19 added support for selinux_content along with the required selinux changes // and should be available starting with Android T Beta 4 // // Android T / 13 (api level 33) - support for shared/selinux_context/pindir #define BPFLOADER_T_VERSION 19u /* For mainline module use, you can #define BPFLOADER_{MIN/MAX}_VER * before #include "bpf_helpers.h" to change which bpfloaders will * process the resulting .o file. * * While this will work outside of mainline too, there just is no point to * using it when the .o and the bpfloader ship in sync with each other. */ #ifndef BPFLOADER_MIN_VER #define BPFLOADER_MIN_VER DEFAULT_BPFLOADER_MIN_VER #endif #ifndef BPFLOADER_MAX_VER #define BPFLOADER_MAX_VER DEFAULT_BPFLOADER_MAX_VER #endif /* place things in different elf sections */ #define SECTION(NAME) __attribute__((section(NAME), used)) /* Must be present in every program, example usage: * LICENSE("GPL"); or LICENSE("Apache 2.0"); * * We also take this opportunity to embed a bunch of other useful values in * the resulting .o (This is to enable some limited forward compatibility * with mainline module shipped ebpf programs) * * The bpfloader_{min/max}_ver defines the [min, max) range of bpfloader * versions that should load this .o file (bpfloaders outside of this range * will simply ignore/skip this *entire* .o) * The [inclusive,exclusive) matches what we do for kernel ver dependencies. * * The size_of_bpf_{map,prog}_def allow the bpfloader to load programs where * these structures have been extended with additional fields (they will of * course simply be ignored then). * * If missing, bpfloader_{min/max}_ver default to 0/0x10000 ie. [v0.0, v1.0), * while size_of_bpf_{map/prog}_def default to 32/20 which are the v0.0 sizes. */ #define LICENSE(NAME) \ unsigned int _bpfloader_min_ver SECTION("bpfloader_min_ver") = BPFLOADER_MIN_VER; \ unsigned int _bpfloader_max_ver SECTION("bpfloader_max_ver") = BPFLOADER_MAX_VER; \ size_t _size_of_bpf_map_def SECTION("size_of_bpf_map_def") = sizeof(struct bpf_map_def); \ size_t _size_of_bpf_prog_def SECTION("size_of_bpf_prog_def") = sizeof(struct bpf_prog_def); \ char _license[] SECTION("license") = (NAME) /* flag the resulting bpf .o file as critical to system functionality, * loading all kernel version appropriate programs in it must succeed * for bpfloader success */ #define CRITICAL(REASON) char _critical[] SECTION("critical") = (REASON) /* * Helper functions called from eBPF programs written in C. These are * implemented in the kernel sources. */ #define KVER_NONE 0 #define KVER(a, b, c) (((a) << 24) + ((b) << 16) + (c)) #define KVER_INF 0xFFFFFFFFu /* generic functions */ /* * Type-unsafe bpf map functions - avoid if possible. * * Using these it is possible to pass in keys/values of the wrong type/size, * or, for 'bpf_map_lookup_elem_unsafe' receive into a pointer to the wrong type. * You will not get a compile time failure, and for certain types of errors you * might not even get a failure from the kernel's ebpf verifier during program load, * instead stuff might just not work right at runtime. * * Instead please use: * DEFINE_BPF_MAP(foo_map, TYPE, KeyType, ValueType, num_entries) * where TYPE can be something like HASH or ARRAY, and num_entries is an integer. * * This defines the map (hence this should not be used in a header file included * from multiple locations) and provides type safe accessors: * ValueType * bpf_foo_map_lookup_elem(const KeyType *) * int bpf_foo_map_update_elem(const KeyType *, const ValueType *, flags) * int bpf_foo_map_delete_elem(const KeyType *) * * This will make sure that if you change the type of a map you'll get compile * errors at any spots you forget to update with the new type. * * Note: these all take pointers to const map because from the C/eBPF point of view * the map struct is really just a readonly map definition of the in kernel object. * Runtime modification of the map defining struct is meaningless, since * the contents is only ever used during bpf program loading & map creation * by the bpf loader, and not by the eBPF program itself. */ static void* (*bpf_map_lookup_elem_unsafe)(const struct bpf_map_def* map, const void* key) = (void*)BPF_FUNC_map_lookup_elem; static int (*bpf_map_update_elem_unsafe)(const struct bpf_map_def* map, const void* key, const void* value, unsigned long long flags) = (void*) BPF_FUNC_map_update_elem; static int (*bpf_map_delete_elem_unsafe)(const struct bpf_map_def* map, const void* key) = (void*)BPF_FUNC_map_delete_elem; #define BPF_ANNOTATE_KV_PAIR(name, type_key, type_val) \ struct ____btf_map_##name { \ type_key key; \ type_val value; \ }; \ struct ____btf_map_##name \ __attribute__ ((section(".maps." #name), used)) \ ____btf_map_##name = { } /* type safe macro to declare a map and related accessor functions */ #define DEFINE_BPF_MAP_EXT(the_map, TYPE, KeyType, ValueType, num_entries, usr, grp, md, \ selinux, pindir, share) \ const struct bpf_map_def SECTION("maps") the_map = { \ .type = BPF_MAP_TYPE_##TYPE, \ .key_size = sizeof(KeyType), \ .value_size = sizeof(ValueType), \ .max_entries = (num_entries), \ .map_flags = 0, \ .uid = (usr), \ .gid = (grp), \ .mode = (md), \ .bpfloader_min_ver = DEFAULT_BPFLOADER_MIN_VER, \ .bpfloader_max_ver = DEFAULT_BPFLOADER_MAX_VER, \ .min_kver = KVER_NONE, \ .max_kver = KVER_INF, \ .selinux_context = selinux, \ .pin_subdir = pindir, \ .shared = share, \ }; \ BPF_ANNOTATE_KV_PAIR(the_map, KeyType, ValueType); \ \ static inline __always_inline __unused ValueType* bpf_##the_map##_lookup_elem( \ const KeyType* k) { \ return bpf_map_lookup_elem_unsafe(&the_map, k); \ }; \ \ static inline __always_inline __unused int bpf_##the_map##_update_elem( \ const KeyType* k, const ValueType* v, unsigned long long flags) { \ return bpf_map_update_elem_unsafe(&the_map, k, v, flags); \ }; \ \ static inline __always_inline __unused int bpf_##the_map##_delete_elem(const KeyType* k) { \ return bpf_map_delete_elem_unsafe(&the_map, k); \ }; #define DEFINE_BPF_MAP_UGM(the_map, TYPE, KeyType, ValueType, num_entries, usr, grp, md) \ DEFINE_BPF_MAP_EXT(the_map, TYPE, KeyType, ValueType, num_entries, usr, grp, md, "", "", false) #define DEFINE_BPF_MAP(the_map, TYPE, KeyType, ValueType, num_entries) \ DEFINE_BPF_MAP_UGM(the_map, TYPE, KeyType, ValueType, num_entries, AID_ROOT, AID_ROOT, 0600) #define DEFINE_BPF_MAP_GWO(the_map, TYPE, KeyType, ValueType, num_entries, gid) \ DEFINE_BPF_MAP_UGM(the_map, TYPE, KeyType, ValueType, num_entries, AID_ROOT, gid, 0620) #define DEFINE_BPF_MAP_GRO(the_map, TYPE, KeyType, ValueType, num_entries, gid) \ DEFINE_BPF_MAP_UGM(the_map, TYPE, KeyType, ValueType, num_entries, AID_ROOT, gid, 0640) #define DEFINE_BPF_MAP_GRW(the_map, TYPE, KeyType, ValueType, num_entries, gid) \ DEFINE_BPF_MAP_UGM(the_map, TYPE, KeyType, ValueType, num_entries, AID_ROOT, gid, 0660) static int (*bpf_probe_read)(void* dst, int size, void* unsafe_ptr) = (void*) BPF_FUNC_probe_read; static int (*bpf_probe_read_str)(void* dst, int size, void* unsafe_ptr) = (void*) BPF_FUNC_probe_read_str; static unsigned long long (*bpf_ktime_get_ns)(void) = (void*) BPF_FUNC_ktime_get_ns; static unsigned long long (*bpf_ktime_get_boot_ns)(void) = (void*)BPF_FUNC_ktime_get_boot_ns; static int (*bpf_trace_printk)(const char* fmt, int fmt_size, ...) = (void*) BPF_FUNC_trace_printk; static unsigned long long (*bpf_get_current_pid_tgid)(void) = (void*) BPF_FUNC_get_current_pid_tgid; static unsigned long long (*bpf_get_current_uid_gid)(void) = (void*) BPF_FUNC_get_current_uid_gid; static unsigned long long (*bpf_get_smp_processor_id)(void) = (void*) BPF_FUNC_get_smp_processor_id; static long (*bpf_get_stackid)(void* ctx, void* map, uint64_t flags) = (void*) BPF_FUNC_get_stackid; static long (*bpf_get_current_comm)(void* buf, uint32_t buf_size) = (void*) BPF_FUNC_get_current_comm; #define DEFINE_BPF_PROG_EXT(SECTION_NAME, prog_uid, prog_gid, the_prog, min_kv, max_kv, opt, \ selinux, pindir) \ const struct bpf_prog_def SECTION("progs") the_prog##_def = { \ .uid = (prog_uid), \ .gid = (prog_gid), \ .min_kver = (min_kv), \ .max_kver = (max_kv), \ .optional = (opt), \ .bpfloader_min_ver = DEFAULT_BPFLOADER_MIN_VER, \ .bpfloader_max_ver = DEFAULT_BPFLOADER_MAX_VER, \ .selinux_context = selinux, \ .pin_subdir = pindir, \ }; \ SECTION(SECTION_NAME) \ int the_prog #define DEFINE_BPF_PROG_KVER_RANGE_OPT(SECTION_NAME, prog_uid, prog_gid, the_prog, min_kv, max_kv, \ opt) \ DEFINE_BPF_PROG_EXT(SECTION_NAME, prog_uid, prog_gid, the_prog, min_kv, max_kv, opt, "", "") // Programs (here used in the sense of functions/sections) marked optional are allowed to fail // to load (for example due to missing kernel patches). // The bpfloader will just ignore these failures and continue processing the next section. // // A non-optional program (function/section) failing to load causes a failure and aborts // processing of the entire .o, if the .o is additionally marked critical, this will result // in the entire bpfloader process terminating with a failure and not setting the bpf.progs_loaded // system property. This in turn results in waitForProgsLoaded() never finishing. // // ie. a non-optional program in a critical .o is mandatory for kernels matching the min/max kver. // programs requiring a kernel version >= min_kv && < max_kv #define DEFINE_BPF_PROG_KVER_RANGE(SECTION_NAME, prog_uid, prog_gid, the_prog, min_kv, max_kv) \ DEFINE_BPF_PROG_KVER_RANGE_OPT(SECTION_NAME, prog_uid, prog_gid, the_prog, min_kv, max_kv, \ false) #define DEFINE_OPTIONAL_BPF_PROG_KVER_RANGE(SECTION_NAME, prog_uid, prog_gid, the_prog, min_kv, \ max_kv) \ DEFINE_BPF_PROG_KVER_RANGE_OPT(SECTION_NAME, prog_uid, prog_gid, the_prog, min_kv, max_kv, true) // programs requiring a kernel version >= min_kv #define DEFINE_BPF_PROG_KVER(SECTION_NAME, prog_uid, prog_gid, the_prog, min_kv) \ DEFINE_BPF_PROG_KVER_RANGE_OPT(SECTION_NAME, prog_uid, prog_gid, the_prog, min_kv, KVER_INF, \ false) #define DEFINE_OPTIONAL_BPF_PROG_KVER(SECTION_NAME, prog_uid, prog_gid, the_prog, min_kv) \ DEFINE_BPF_PROG_KVER_RANGE_OPT(SECTION_NAME, prog_uid, prog_gid, the_prog, min_kv, KVER_INF, \ true) // programs with no kernel version requirements #define DEFINE_BPF_PROG(SECTION_NAME, prog_uid, prog_gid, the_prog) \ DEFINE_BPF_PROG_KVER_RANGE_OPT(SECTION_NAME, prog_uid, prog_gid, the_prog, 0, KVER_INF, false) #define DEFINE_OPTIONAL_BPF_PROG(SECTION_NAME, prog_uid, prog_gid, the_prog) \ DEFINE_BPF_PROG_KVER_RANGE_OPT(SECTION_NAME, prog_uid, prog_gid, the_prog, 0, KVER_INF, true)