| Alexei Starovoitov | d0003ec | 2014-11-13 17:36:49 -0800 | [diff] [blame] | 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 | }; |