From: Jakub Kicinski Date: Wed, 21 Sep 2016 10:43:59 +0000 (+0100) Subject: bpf: recognize 64bit immediate loads as consts X-Git-Tag: v4.9-rc1~127^2~117^2~8 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=6b17387307ba;p=karo-tx-linux.git 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 --- 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);