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author | Alexei Starovoitov <ast@plumgrid.com> | 2014-11-13 17:36:49 -0800 |
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committer | David S. Miller <davem@davemloft.net> | 2014-11-18 13:44:00 -0500 |
commit | d0003ec01c667b731c139e23de3306a8b328ccf5 (patch) | |
tree | a0156f2487c49537507d46f730c9e9ca9c4667c4 /kernel/bpf/helpers.c | |
parent | ffb65f27a15583379567b6a59a9758163b7f5750 (diff) | |
download | linux-d0003ec01c667b731c139e23de3306a8b328ccf5.tar.gz linux-d0003ec01c667b731c139e23de3306a8b328ccf5.tar.bz2 linux-d0003ec01c667b731c139e23de3306a8b328ccf5.zip |
bpf: allow eBPF programs to use maps
expose bpf_map_lookup_elem(), bpf_map_update_elem(), bpf_map_delete_elem()
map accessors to eBPF programs
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/bpf/helpers.c')
-rw-r--r-- | kernel/bpf/helpers.c | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c new file mode 100644 index 000000000000..9e3414d85459 --- /dev/null +++ b/kernel/bpf/helpers.c @@ -0,0 +1,89 @@ +/* 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> + +/* 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; +} + +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); +} + +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); +} + +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, +}; |