From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brenden Blanco Subject: [PATCH v10 11/12] bpf: enable direct packet data write for xdp progs Date: Tue, 19 Jul 2016 12:16:56 -0700 Message-ID: <1468955817-10604-12-git-send-email-bblanco@plumgrid.com> References: <1468955817-10604-1-git-send-email-bblanco@plumgrid.com> Cc: Brenden Blanco , Jamal Hadi Salim , Saeed Mahameed , Martin KaFai Lau , Jesper Dangaard Brouer , Ari Saha , Alexei Starovoitov , Or Gerlitz , john.fastabend@gmail.com, hannes@stressinduktion.org, Thomas Graf , Tom Herbert , Daniel Borkmann , Tariq Toukan To: davem@davemloft.net, netdev@vger.kernel.org Return-path: Received: from mail-pf0-f169.google.com ([209.85.192.169]:36325 "EHLO mail-pf0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751937AbcGSTRg (ORCPT ); Tue, 19 Jul 2016 15:17:36 -0400 Received: by mail-pf0-f169.google.com with SMTP id h186so10142812pfg.3 for ; Tue, 19 Jul 2016 12:17:36 -0700 (PDT) In-Reply-To: <1468955817-10604-1-git-send-email-bblanco@plumgrid.com> Sender: netdev-owner@vger.kernel.org List-ID: For forwarding to be effective, XDP programs should be allowed to rewrite packet data. This requires that the drivers supporting XDP must all map the packet memory as TODEVICE or BIDIRECTIONAL before invoking the program. Signed-off-by: Brenden Blanco --- kernel/bpf/verifier.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index a8d67d0..f72f23b 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -653,6 +653,16 @@ static int check_map_access(struct verifier_env *env, u32 regno, int off, #define MAX_PACKET_OFF 0xffff +static bool may_write_pkt_data(enum bpf_prog_type type) +{ + switch (type) { + case BPF_PROG_TYPE_XDP: + return true; + default: + return false; + } +} + static int check_packet_access(struct verifier_env *env, u32 regno, int off, int size) { @@ -806,10 +816,15 @@ static int check_mem_access(struct verifier_env *env, u32 regno, int off, err = check_stack_read(state, off, size, value_regno); } } else if (state->regs[regno].type == PTR_TO_PACKET) { - if (t == BPF_WRITE) { + if (t == BPF_WRITE && !may_write_pkt_data(env->prog->type)) { verbose("cannot write into packet\n"); return -EACCES; } + if (t == BPF_WRITE && value_regno >= 0 && + is_pointer_value(env, value_regno)) { + verbose("R%d leaks addr into packet\n", value_regno); + return -EACCES; + } err = check_packet_access(env, regno, off, size); if (!err && t == BPF_READ && value_regno >= 0) mark_reg_unknown_value(state->regs, value_regno); -- 2.8.2