netdev - [PATCH bpf-next 6/6] nfp: bpf: reject program on instructions unknown to the JIT compiler

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Date:   Tue, 16 Jan 2018 15:51:50 -0800
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     daniel@...earbox.net, alexei.starovoitov@...il.com
Cc:     netdev@...r.kernel.org, oss-drivers@...ronome.com,
        Quentin Monnet <quentin.monnet@...ronome.com>
Subject: [PATCH bpf-next 6/6] nfp: bpf: reject program on instructions unknown to the JIT compiler

From: Quentin Monnet <quentin.monnet@...ronome.com>

If an eBPF instruction is unknown to the driver JIT compiler, we can
reject the program at verification time.

Signed-off-by: Quentin Monnet <quentin.monnet@...ronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
Reviewed-by: Jiong Wang <jiong.wang@...ronome.com>
---
 drivers/net/ethernet/netronome/nfp/bpf/jit.c      | 5 +++++
 drivers/net/ethernet/netronome/nfp/bpf/main.h     | 1 +
 drivers/net/ethernet/netronome/nfp/bpf/verifier.c | 6 ++++++
 3 files changed, 12 insertions(+)

diff --git a/drivers/net/ethernet/netronome/nfp/bpf/jit.c b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
index cdc949fabe98..56451edf01c2 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/jit.c
+++ b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
@@ -2907,6 +2907,11 @@ void nfp_bpf_jit_prepare(struct nfp_prog *nfp_prog, unsigned int cnt)
 	}
 }
 
+bool nfp_bpf_supported_opcode(u8 code)
+{
+	return !!instr_cb[code];
+}
+
 void *nfp_bpf_relo_for_vnic(struct nfp_prog *nfp_prog, struct nfp_bpf_vnic *bv)
 {
 	unsigned int i;
diff --git a/drivers/net/ethernet/netronome/nfp/bpf/main.h b/drivers/net/ethernet/netronome/nfp/bpf/main.h
index 80855d43b25e..424fe8338105 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/main.h
+++ b/drivers/net/ethernet/netronome/nfp/bpf/main.h
@@ -324,6 +324,7 @@ struct nfp_bpf_vnic {
 
 void nfp_bpf_jit_prepare(struct nfp_prog *nfp_prog, unsigned int cnt);
 int nfp_bpf_jit(struct nfp_prog *prog);
+bool nfp_bpf_supported_opcode(u8 code);
 
 extern const struct bpf_prog_offload_ops nfp_bpf_analyzer_ops;
 
diff --git a/drivers/net/ethernet/netronome/nfp/bpf/verifier.c b/drivers/net/ethernet/netronome/nfp/bpf/verifier.c
index 81dab462456c..479f602887e9 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/verifier.c
+++ b/drivers/net/ethernet/netronome/nfp/bpf/verifier.c
@@ -290,6 +290,12 @@ nfp_verify_insn(struct bpf_verifier_env *env, int insn_idx, int prev_insn_idx)
 	meta = nfp_bpf_goto_meta(nfp_prog, meta, insn_idx, env->prog->len);
 	nfp_prog->verifier_meta = meta;
 
+	if (!nfp_bpf_supported_opcode(meta->insn.code)) {
+		pr_vlog(env, "instruction %#02x not supported\n",
+			meta->insn.code);
+		return -EINVAL;
+	}
+
 	if (meta->insn.src_reg >= MAX_BPF_REG ||
 	    meta->insn.dst_reg >= MAX_BPF_REG) {
 		pr_vlog(env, "program uses extended registers - jit hardening?\n");
-- 
2.15.1