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Date: Fri, 4 Sep 2015 10:04:24 -0600 From: Tycho Andersen <tycho.andersen@...onical.com> To: Kees Cook <keescook@...omium.org>, Alexei Starovoitov <ast@...nel.org> Cc: Will Drewry <wad@...omium.org>, Oleg Nesterov <oleg@...hat.com>, Andy Lutomirski <luto@...capital.net>, Pavel Emelyanov <xemul@...allels.com>, "Serge E. Hallyn" <serge.hallyn@...ntu.com>, Daniel Borkmann <daniel@...earbox.net>, linux-kernel@...r.kernel.org, netdev@...r.kernel.org, Tycho Andersen <tycho.andersen@...onical.com> Subject: [PATCH 6/6] ebpf: allow BPF_REG_X in src_reg conditional jumps 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 <tycho.andersen@...onical.com> CC: Kees Cook <keescook@...omium.org> CC: Will Drewry <wad@...omium.org> CC: Oleg Nesterov <oleg@...hat.com> CC: Andy Lutomirski <luto@...capital.net> CC: Pavel Emelyanov <xemul@...allels.com> CC: Serge E. Hallyn <serge.hallyn@...ntu.com> CC: Alexei Starovoitov <ast@...nel.org> CC: Daniel Borkmann <daniel@...earbox.net> --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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