From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tycho Andersen Subject: [PATCH 6/6] ebpf: allow BPF_REG_X in src_reg conditional jumps Date: Fri, 4 Sep 2015 10:04:24 -0600 Message-ID: <1441382664-17437-7-git-send-email-tycho.andersen@canonical.com> References: <1441382664-17437-1-git-send-email-tycho.andersen@canonical.com> Cc: Will Drewry , Oleg Nesterov , Andy Lutomirski , Pavel Emelyanov , "Serge E. Hallyn" , Daniel Borkmann , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Tycho Andersen To: Kees Cook , Alexei Starovoitov Return-path: In-Reply-To: <1441382664-17437-1-git-send-email-tycho.andersen@canonical.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org The classic converter generates conditional jumps with: if (BPF_SRC(fp->code) == BPF_K && (int) fp->k < 0) { ... } else { insn->dst_reg = BPF_REG_A; insn->src_reg = BPF_REG_X; insn->imm = fp->k; bpf_src = BPF_SRC(fp->code); } but here, we enforce that the src_reg == BPF_REG_0. We should also allow BPF_REG_X since that's what the converter generates; this enables us to load eBPF programs that were generated by the converter. Signed-off-by: Tycho Andersen CC: Kees Cook CC: Will Drewry CC: Oleg Nesterov CC: Andy Lutomirski CC: Pavel Emelyanov CC: Serge E. Hallyn CC: Alexei Starovoitov CC: Daniel Borkmann --- kernel/bpf/verifier.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 039d866..2fff8cd 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1080,7 +1080,12 @@ static int check_cond_jmp_op(struct verifier_env *env, if (err) return err; } else { - if (insn->src_reg != BPF_REG_0) { + switch (insn->src_reg) { + case BPF_REG_0: + /* the classic converter generates BPF_JMP with src_reg of X */ + case BPF_REG_X: + break; + default: verbose("BPF_JMP uses reserved fields\n"); return -EINVAL; } -- 2.1.4