[PATCH net-next 2/6] bpf: refactor fixup_bpf_calls()
From: Alexei Starovoitov <hidden>
Date: 2017-03-16 01:26:50
Subsystem:
bpf [core], bpf [general] (safe dynamic programs and tools), the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Linus Torvalds
reduce indent and make it iterate over instructions similar to convert_ctx_accesses(). Also convert hard BUG_ON into soft verifier error. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> --- kernel/bpf/verifier.c | 76 ++++++++++++++++++++++++--------------------------- 1 file changed, 35 insertions(+), 41 deletions(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index e41da6c57053..5dfa9b8111da 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c@@ -3233,59 +3233,53 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env) return 0; } -/* fixup insn->imm field of bpf_call instructions: - * if (insn->imm == BPF_FUNC_map_lookup_elem) - * insn->imm = bpf_map_lookup_elem - __bpf_call_base; - * else if (insn->imm == BPF_FUNC_map_update_elem) - * insn->imm = bpf_map_update_elem - __bpf_call_base; - * else ... +/* fixup insn->imm field of bpf_call instructions * * this function is called after eBPF program passed verification */ -static void fixup_bpf_calls(struct bpf_prog *prog) +static int fixup_bpf_calls(struct bpf_verifier_env *env) { + struct bpf_prog *prog = env->prog; + struct bpf_insn *insn = prog->insnsi; const struct bpf_func_proto *fn; + const int insn_cnt = prog->len; int i; - for (i = 0; i < prog->len; i++) { - struct bpf_insn *insn = &prog->insnsi[i]; + for (i = 0; i < insn_cnt; i++, insn++) { + if (insn->code != (BPF_JMP | BPF_CALL)) + continue; - if (insn->code == (BPF_JMP | BPF_CALL)) { - /* we reach here when program has bpf_call instructions - * and it passed bpf_check(), means that - * ops->get_func_proto must have been supplied, check it + if (insn->imm == BPF_FUNC_get_route_realm) + prog->dst_needed = 1; + if (insn->imm == BPF_FUNC_get_prandom_u32) + bpf_user_rnd_init_once(); + if (insn->imm == BPF_FUNC_xdp_adjust_head) + prog->xdp_adjust_head = 1; + if (insn->imm == BPF_FUNC_tail_call) { + /* mark bpf_tail_call as different opcode to avoid + * conditional branch in the interpeter for every normal + * call and to prevent accidental JITing by JIT compiler + * that doesn't support bpf_tail_call yet */ - BUG_ON(!prog->aux->ops->get_func_proto); - - if (insn->imm == BPF_FUNC_get_route_realm) - prog->dst_needed = 1; - if (insn->imm == BPF_FUNC_get_prandom_u32) - bpf_user_rnd_init_once(); - if (insn->imm == BPF_FUNC_xdp_adjust_head) - prog->xdp_adjust_head = 1; - if (insn->imm == BPF_FUNC_tail_call) { - /* mark bpf_tail_call as different opcode - * to avoid conditional branch in - * interpeter for every normal call - * and to prevent accidental JITing by - * JIT compiler that doesn't support - * bpf_tail_call yet - */ - insn->imm = 0; - insn->code |= BPF_X; - continue; - } + insn->imm = 0; + insn->code |= BPF_X; + continue; + } - fn = prog->aux->ops->get_func_proto(insn->imm); - /* all functions that have prototype and verifier allowed - * programs to call them, must be real in-kernel functions - */ - BUG_ON(!fn->func); - insn->imm = fn->func - __bpf_call_base; + fn = prog->aux->ops->get_func_proto(insn->imm); + /* all functions that have prototype and verifier allowed + * programs to call them, must be real in-kernel functions + */ + if (!fn->func) { + verbose("kernel subsystem misconfigured func %s#%d\n", + func_id_name(insn->imm), insn->imm); + return -EFAULT; } + insn->imm = fn->func - __bpf_call_base; } -} + return 0; +} static void free_states(struct bpf_verifier_env *env) {
@@ -3383,7 +3377,7 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr) ret = convert_ctx_accesses(env); if (ret == 0) - fixup_bpf_calls(env->prog); + ret = fixup_bpf_calls(env); if (log_level && log_len >= log_size - 1) { BUG_ON(log_len >= log_size);
--
2.8.0