diff options
| author | Roman Gushchin <guro@fb.com> | 2018-08-02 14:27:22 -0700 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2018-08-03 00:47:32 +0200 |
| commit | 3e6a4b3e0289dc9540a2c1d8a20657f4707fbabb (patch) | |
| tree | a8265b30b1738086a0c89cb5f581a0766c82ec63 | |
| parent | 394e40a29788820c9c0526b1c3497c9e0ec2a126 (diff) | |
| download | linux-3e6a4b3e0289dc9540a2c1d8a20657f4707fbabb.tar.bz2 | |
bpf/verifier: introduce BPF_PTR_TO_MAP_VALUE
BPF_MAP_TYPE_CGROUP_STORAGE maps are special in a way
that the access from the bpf program side is lookup-free.
That means the result is guaranteed to be a valid
pointer to the cgroup storage; no NULL-check is required.
This patch introduces BPF_PTR_TO_MAP_VALUE return type,
which is required to cause the verifier accept programs,
which are not checking the map value pointer for being NULL.
Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
| -rw-r--r-- | include/linux/bpf.h | 1 | ||||
| -rw-r--r-- | kernel/bpf/verifier.c | 8 |
2 files changed, 7 insertions, 2 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 16be67888c30..ca4ac2a39def 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -155,6 +155,7 @@ enum bpf_arg_type { enum bpf_return_type { RET_INTEGER, /* function returns integer */ RET_VOID, /* function doesn't return anything */ + RET_PTR_TO_MAP_VALUE, /* returns a pointer to map elem value */ RET_PTR_TO_MAP_VALUE_OR_NULL, /* returns a pointer to map elem value or NULL */ }; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 7e75434a9e54..1ede16c8bb40 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2545,8 +2545,12 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn mark_reg_unknown(env, regs, BPF_REG_0); } else if (fn->ret_type == RET_VOID) { regs[BPF_REG_0].type = NOT_INIT; - } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL) { - regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL; + } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL || + fn->ret_type == RET_PTR_TO_MAP_VALUE) { + if (fn->ret_type == RET_PTR_TO_MAP_VALUE) + regs[BPF_REG_0].type = PTR_TO_MAP_VALUE; + else + regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL; /* There is no offset yet applied, variable or fixed */ mark_reg_known_zero(env, regs, BPF_REG_0); regs[BPF_REG_0].off = 0; |