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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 | }; |