diff options
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/Makefile | 2 | ||||
| -rw-r--r-- | kernel/bpf/helpers.c | 89 |
2 files changed, 90 insertions, 1 deletions
diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile index 72ec98ba2d42..a5ae60f0b0a2 100644 --- a/kernel/bpf/Makefile +++ b/kernel/bpf/Makefile @@ -1,5 +1,5 @@ obj-y := core.o -obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o hashtab.o arraymap.o +obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o hashtab.o arraymap.o helpers.o ifdef CONFIG_TEST_BPF obj-$(CONFIG_BPF_SYSCALL) += test_stub.o endif 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, +}; |