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Message-ID: <1472780246-323814-2-git-send-email-ast@fb.com>
Date: Thu, 1 Sep 2016 18:37:21 -0700
From: Alexei Starovoitov <ast@...com>
To: "David S . Miller" <davem@...emloft.net>
CC: Peter Zijlstra <peterz@...radead.org>,
Brendan Gregg <bgregg@...flix.com>,
Daniel Borkmann <daniel@...earbox.net>,
Arnaldo Carvalho de Melo <acme@...radead.org>,
Wang Nan <wangnan0@...wei.com>, <netdev@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <kernel-team@...com>
Subject: [PATCH v3 net-next 1/6] bpf: support 8-byte metafield access
The verifier supported only 4-byte metafields in
struct __sk_buff and struct xdp_md. The metafields in upcoming
struct bpf_perf_event are 8-byte to match register width in struct pt_regs.
Teach verifier to recognize 8-byte metafield access.
The patch doesn't affect safety of sockets and xdp programs.
They check for 4-byte only ctx access before these conditions are hit.
Signed-off-by: Alexei Starovoitov <ast@...nel.org>
Acked-by: Daniel Borkmann <daniel@...earbox.net>
---
kernel/bpf/verifier.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index abb61f3f6900..c1c9e441f0f5 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2333,7 +2333,8 @@ static int do_check(struct verifier_env *env)
if (err)
return err;
- if (BPF_SIZE(insn->code) != BPF_W) {
+ if (BPF_SIZE(insn->code) != BPF_W &&
+ BPF_SIZE(insn->code) != BPF_DW) {
insn_idx++;
continue;
}
@@ -2642,9 +2643,11 @@ static int convert_ctx_accesses(struct verifier_env *env)
for (i = 0; i < insn_cnt; i++, insn++) {
u32 insn_delta, cnt;
- if (insn->code == (BPF_LDX | BPF_MEM | BPF_W))
+ if (insn->code == (BPF_LDX | BPF_MEM | BPF_W) ||
+ insn->code == (BPF_LDX | BPF_MEM | BPF_DW))
type = BPF_READ;
- else if (insn->code == (BPF_STX | BPF_MEM | BPF_W))
+ else if (insn->code == (BPF_STX | BPF_MEM | BPF_W) ||
+ insn->code == (BPF_STX | BPF_MEM | BPF_DW))
type = BPF_WRITE;
else
continue;
--
2.8.0
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