/* Common BPF helpers to be used by all BPF programs loaded by Android */ #include #include #include #include "bpf_map_def.h" /* place things in different elf sections */ #define SEC(NAME) __attribute__((section(NAME), used)) /* Example use: LICENSE("GPL"); or LICENSE("Apache 2.0"); */ #define LICENSE(NAME) char _license[] SEC("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[] SEC("critical") = (REASON) /* * Helper functions called from eBPF programs written in C. These are * implemented in the kernel sources. */ /* 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 'const void* 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 void* map, const void* key) = (void*)BPF_FUNC_map_lookup_elem; static int (*bpf_map_update_elem_unsafe)(const void* 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 void* map, const void* key) = (void*)BPF_FUNC_map_delete_elem; /* type safe macro to declare a map and related accessor functions */ #define DEFINE_BPF_MAP_UGM(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries, usr, grp, md) \ const struct bpf_map_def SEC("maps") the_map = { \ .type = BPF_MAP_TYPE_##TYPE, \ .key_size = sizeof(TypeOfKey), \ .value_size = sizeof(TypeOfValue), \ .max_entries = (num_entries), \ .uid = (usr), \ .gid = (grp), \ .mode = (md), \ }; \ \ static inline __always_inline __unused TypeOfValue* bpf_##the_map##_lookup_elem( \ const TypeOfKey* k) { \ return bpf_map_lookup_elem_unsafe(&the_map, k); \ }; \ \ static inline __always_inline __unused int bpf_##the_map##_update_elem( \ const TypeOfKey* k, const TypeOfValue* 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 TypeOfKey* k) { \ return bpf_map_delete_elem_unsafe(&the_map, k); \ }; #define DEFINE_BPF_MAP(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries) \ DEFINE_BPF_MAP_UGM(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries, AID_ROOT, AID_ROOT, 0600) #define DEFINE_BPF_MAP_GWO(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries, gid) \ DEFINE_BPF_MAP_UGM(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries, AID_ROOT, gid, 0620) #define DEFINE_BPF_MAP_GRO(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries, gid) \ DEFINE_BPF_MAP_UGM(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries, AID_ROOT, gid, 0640) #define DEFINE_BPF_MAP_GRW(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries, gid) \ DEFINE_BPF_MAP_UGM(the_map, TYPE, TypeOfKey, TypeOfValue, 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 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; #define KVER_NONE 0 #define KVER(a, b, c) ((a)*65536 + (b)*256 + (c)) #define KVER_INF 0xFFFFFFFF #define DEFINE_BPF_PROG_KVER_RANGE_OPT(SECTION_NAME, prog_uid, prog_gid, the_prog, min_kv, max_kv, \ opt) \ const struct bpf_prog_def SEC("progs") the_prog##_def = { \ .uid = (prog_uid), \ .gid = (prog_gid), \ .min_kver = (min_kv), \ .max_kver = (max_kv), \ .optional = (opt), \ }; \ SEC(SECTION_NAME) \ int the_prog // 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)