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 15 /* If kernel subsystem is allowing eBPF programs to call this function, 16 * inside its own verifier_ops->get_func_proto() callback it should return 17 * bpf_map_lookup_elem_proto, so that verifier can properly check the arguments 18 * 19 * Different map implementations will rely on rcu in map methods 20 * lookup/update/delete, therefore eBPF programs must run under rcu lock 21 * if program is allowed to access maps, so check rcu_read_lock_held in 22 * all three functions. 23 */ 24 static u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) 25 { 26 /* verifier checked that R1 contains a valid pointer to bpf_map 27 * and R2 points to a program stack and map->key_size bytes were 28 * initialized 29 */ 30 struct bpf_map *map = (struct bpf_map *) (unsigned long) r1; 31 void *key = (void *) (unsigned long) r2; 32 void *value; 33 34 WARN_ON_ONCE(!rcu_read_lock_held()); 35 36 value = map->ops->map_lookup_elem(map, key); 37 38 /* lookup() returns either pointer to element value or NULL 39 * which is the meaning of PTR_TO_MAP_VALUE_OR_NULL type 40 */ 41 return (unsigned long) value; 42 } 43 44 struct bpf_func_proto bpf_map_lookup_elem_proto = { 45 .func = bpf_map_lookup_elem, 46 .gpl_only = false, 47 .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL, 48 .arg1_type = ARG_CONST_MAP_PTR, 49 .arg2_type = ARG_PTR_TO_MAP_KEY, 50 }; 51 52 static u64 bpf_map_update_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) 53 { 54 struct bpf_map *map = (struct bpf_map *) (unsigned long) r1; 55 void *key = (void *) (unsigned long) r2; 56 void *value = (void *) (unsigned long) r3; 57 58 WARN_ON_ONCE(!rcu_read_lock_held()); 59 60 return map->ops->map_update_elem(map, key, value, r4); 61 } 62 63 struct bpf_func_proto bpf_map_update_elem_proto = { 64 .func = bpf_map_update_elem, 65 .gpl_only = false, 66 .ret_type = RET_INTEGER, 67 .arg1_type = ARG_CONST_MAP_PTR, 68 .arg2_type = ARG_PTR_TO_MAP_KEY, 69 .arg3_type = ARG_PTR_TO_MAP_VALUE, 70 .arg4_type = ARG_ANYTHING, 71 }; 72 73 static u64 bpf_map_delete_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) 74 { 75 struct bpf_map *map = (struct bpf_map *) (unsigned long) r1; 76 void *key = (void *) (unsigned long) r2; 77 78 WARN_ON_ONCE(!rcu_read_lock_held()); 79 80 return map->ops->map_delete_elem(map, key); 81 } 82 83 struct bpf_func_proto bpf_map_delete_elem_proto = { 84 .func = bpf_map_delete_elem, 85 .gpl_only = false, 86 .ret_type = RET_INTEGER, 87 .arg1_type = ARG_CONST_MAP_PTR, 88 .arg2_type = ARG_PTR_TO_MAP_KEY, 89 }; 90