[NETD-BPF#23] Move a few headers to frameworks/libs/net

BPF headers used by both platform and mainline modules should be in
frameworks/libs/net.

Bug: 202086915
Test: build and boot
Test: cd packages/modules/Connectivity/netd; atest
Change-Id: Ie6f257b022cdea6bab3389a9fa41791f893e54c3

1 files changed, 216 insertions, 0 deletions

diff --git a/common/native/bpf_headers/include/bpf/bpf_helpers.h b/common/native/bpf_headers/include/bpf/bpf_helpers.h
new file mode 100644
index 00000000..878bb103
--- /dev/null
+++ b/common/native/bpf_headers/include/bpf/bpf_helpers.h
@@ -0,0 +1,216 @@
+/* Common BPF helpers to be used by all BPF programs loaded by Android */
+
+#include <linux/bpf.h>
+#include <stdbool.h>
+#include <stdint.h>
+
+#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.               *
+ *                                                                            *
+ ******************************************************************************/
+
+/* 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;
+
+/* 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 SECTION("maps") the_map = {                                         \
+            .type = BPF_MAP_TYPE_##TYPE,                                                         \
+            .key_size = sizeof(TypeOfKey),                                                       \
+            .value_size = sizeof(TypeOfValue),                                                   \
+            .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,                                                                \
+    };                                                                                           \
+                                                                                                 \
+    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 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;
+
+#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 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,                                        \
+    };                                                                                             \
+    SECTION(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)