1 files changed, 113 insertions, 0 deletions

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
new file mode 100644
index 000000000000..bd7f5988ed9c
--- /dev/null
+++ b/kernel/bpf/helpers.c
@@ -0,0 +1,113 @@
+/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+#include <linux/bpf.h>
+#include <linux/rcupdate.h>
+#include <linux/random.h>
+#include <linux/smp.h>
+
+/* If kernel subsystem is allowing eBPF programs to call this function,
+ * inside its own verifier_ops->get_func_proto() callback it should return
+ * bpf_map_lookup_elem_proto, so that verifier can properly check the arguments
+ *
+ * Different map implementations will rely on rcu in map methods
+ * lookup/update/delete, therefore eBPF programs must run under rcu lock
+ * if program is allowed to access maps, so check rcu_read_lock_held in
+ * all three functions.
+ */
+static u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
+{
+        /* verifier checked that R1 contains a valid pointer to bpf_map
+         * and R2 points to a program stack and map->key_size bytes were
+         * initialized
+         */
+        struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
+        void *key = (void *) (unsigned long) r2;
+        void *value;
+
+        WARN_ON_ONCE(!rcu_read_lock_held());
+
+        value = map->ops->map_lookup_elem(map, key);
+
+        /* lookup() returns either pointer to element value or NULL
+         * which is the meaning of PTR_TO_MAP_VALUE_OR_NULL type
+         */
+        return (unsigned long) value;
+}
+
+const struct bpf_func_proto bpf_map_lookup_elem_proto = {
+        .func = bpf_map_lookup_elem,
+        .gpl_only = false,
+        .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
+        .arg1_type = ARG_CONST_MAP_PTR,
+        .arg2_type = ARG_PTR_TO_MAP_KEY,
+};
+
+static u64 bpf_map_update_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
+{
+        struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
+        void *key = (void *) (unsigned long) r2;
+        void *value = (void *) (unsigned long) r3;
+
+        WARN_ON_ONCE(!rcu_read_lock_held());
+
+        return map->ops->map_update_elem(map, key, value, r4);
+}
+
+const struct bpf_func_proto bpf_map_update_elem_proto = {
+        .func = bpf_map_update_elem,
+        .gpl_only = false,
+        .ret_type = RET_INTEGER,
+        .arg1_type = ARG_CONST_MAP_PTR,
+        .arg2_type = ARG_PTR_TO_MAP_KEY,
+        .arg3_type = ARG_PTR_TO_MAP_VALUE,
+        .arg4_type = ARG_ANYTHING,
+};
+
+static u64 bpf_map_delete_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
+{
+        struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
+        void *key = (void *) (unsigned long) r2;
+
+        WARN_ON_ONCE(!rcu_read_lock_held());
+
+        return map->ops->map_delete_elem(map, key);
+}
+
+const struct bpf_func_proto bpf_map_delete_elem_proto = {
+        .func = bpf_map_delete_elem,
+        .gpl_only = false,
+        .ret_type = RET_INTEGER,
+        .arg1_type = ARG_CONST_MAP_PTR,
+        .arg2_type = ARG_PTR_TO_MAP_KEY,
+};
+
+static u64 bpf_get_prandom_u32(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
+{
+        return prandom_u32();
+}
+
+const struct bpf_func_proto bpf_get_prandom_u32_proto = {
+        .func           = bpf_get_prandom_u32,
+        .gpl_only       = false,
+        .ret_type       = RET_INTEGER,
+};
+
+static u64 bpf_get_smp_processor_id(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
+{
+        return raw_smp_processor_id();
+}
+
+const struct bpf_func_proto bpf_get_smp_processor_id_proto = {
+        .func           = bpf_get_smp_processor_id,
+        .gpl_only       = false,
+        .ret_type       = RET_INTEGER,
+};