From 6b17387307bafc71624b9890b9239b6a438e2e89 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Wed, 21 Sep 2016 11:43:59 +0100 Subject: [PATCH] bpf: recognize 64bit immediate loads as consts When running as parser interpret BPF_LD | BPF_IMM | BPF_DW instructions as loading CONST_IMM with the value stored in imm. The verifier will continue not recognizing those due to concerns about search space/program complexity increase. Signed-off-by: Jakub Kicinski Acked-by: Alexei Starovoitov Acked-by: Daniel Borkmann Signed-off-by: David S. Miller --- kernel/bpf/verifier.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index ee86a77dc40b..8c3f794c7028 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1769,9 +1769,19 @@ static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn) if (err) return err; - if (insn->src_reg == 0) - /* generic move 64-bit immediate into a register */ + if (insn->src_reg == 0) { + /* generic move 64-bit immediate into a register, + * only analyzer needs to collect the ld_imm value. + */ + u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm; + + if (!env->analyzer_ops) + return 0; + + regs[insn->dst_reg].type = CONST_IMM; + regs[insn->dst_reg].imm = imm; return 0; + } /* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */ BUG_ON(insn->src_reg != BPF_PSEUDO_MAP_FD); -- 2.11.0