1 /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com 2 * 3 * This program is free software; you can redistribute it and/or 4 * modify it under the terms of version 2 of the GNU General Public 5 * License as published by the Free Software Foundation. 6 * 7 * This program is distributed in the hope that it will be useful, but 8 * WITHOUT ANY WARRANTY; without even the implied warranty of 9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 10 * General Public License for more details. 11 */ 12 #include <linux/bpf.h> 13 #include <linux/rcupdate.h> 14 #include <linux/random.h> 15 #include <linux/smp.h> 16 #include <linux/ktime.h> 17 18 /* If kernel subsystem is allowing eBPF programs to call this function, 19 * inside its own verifier_ops->get_func_proto() callback it should return 20 * bpf_map_lookup_elem_proto, so that verifier can properly check the arguments 21 * 22 * Different map implementations will rely on rcu in map methods 23 * lookup/update/delete, therefore eBPF programs must run under rcu lock 24 * if program is allowed to access maps, so check rcu_read_lock_held in 25 * all three functions. 26 */ 27 static u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) 28 { 29 /* verifier checked that R1 contains a valid pointer to bpf_map 30 * and R2 points to a program stack and map->key_size bytes were 31 * initialized 32 */ 33 struct bpf_map *map = (struct bpf_map *) (unsigned long) r1; 34 void *key = (void *) (unsigned long) r2; 35 void *value; 36 37 WARN_ON_ONCE(!rcu_read_lock_held()); 38 39 value = map->ops->map_lookup_elem(map, key); 40 41 /* lookup() returns either pointer to element value or NULL 42 * which is the meaning of PTR_TO_MAP_VALUE_OR_NULL type 43 */ 44 return (unsigned long) value; 45 } 46 47 const struct bpf_func_proto bpf_map_lookup_elem_proto = { 48 .func = bpf_map_lookup_elem, 49 .gpl_only = false, 50 .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL, 51 .arg1_type = ARG_CONST_MAP_PTR, 52 .arg2_type = ARG_PTR_TO_MAP_KEY, 53 }; 54 55 static u64 bpf_map_update_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) 56 { 57 struct bpf_map *map = (struct bpf_map *) (unsigned long) r1; 58 void *key = (void *) (unsigned long) r2; 59 void *value = (void *) (unsigned long) r3; 60 61 WARN_ON_ONCE(!rcu_read_lock_held()); 62 63 return map->ops->map_update_elem(map, key, value, r4); 64 } 65 66 const struct bpf_func_proto bpf_map_update_elem_proto = { 67 .func = bpf_map_update_elem, 68 .gpl_only = false, 69 .ret_type = RET_INTEGER, 70 .arg1_type = ARG_CONST_MAP_PTR, 71 .arg2_type = ARG_PTR_TO_MAP_KEY, 72 .arg3_type = ARG_PTR_TO_MAP_VALUE, 73 .arg4_type = ARG_ANYTHING, 74 }; 75 76 static u64 bpf_map_delete_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) 77 { 78 struct bpf_map *map = (struct bpf_map *) (unsigned long) r1; 79 void *key = (void *) (unsigned long) r2; 80 81 WARN_ON_ONCE(!rcu_read_lock_held()); 82 83 return map->ops->map_delete_elem(map, key); 84 } 85 86 const struct bpf_func_proto bpf_map_delete_elem_proto = { 87 .func = bpf_map_delete_elem, 88 .gpl_only = false, 89 .ret_type = RET_INTEGER, 90 .arg1_type = ARG_CONST_MAP_PTR, 91 .arg2_type = ARG_PTR_TO_MAP_KEY, 92 }; 93 94 static u64 bpf_get_prandom_u32(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) 95 { 96 return prandom_u32(); 97 } 98 99 const struct bpf_func_proto bpf_get_prandom_u32_proto = { 100 .func = bpf_get_prandom_u32, 101 .gpl_only = false, 102 .ret_type = RET_INTEGER, 103 }; 104 105 static u64 bpf_get_smp_processor_id(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) 106 { 107 return raw_smp_processor_id(); 108 } 109 110 const struct bpf_func_proto bpf_get_smp_processor_id_proto = { 111 .func = bpf_get_smp_processor_id, 112 .gpl_only = false, 113 .ret_type = RET_INTEGER, 114 }; 115 116 static u64 bpf_ktime_get_ns(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) 117 { 118 /* NMI safe access to clock monotonic */ 119 return ktime_get_mono_fast_ns(); 120 } 121 122 const struct bpf_func_proto bpf_ktime_get_ns_proto = { 123 .func = bpf_ktime_get_ns, 124 .gpl_only = true, 125 .ret_type = RET_INTEGER, 126 }; 127