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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@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexei Starovoitov 2016-09-01 18:37:21 -07:00 committed by David S. Miller
parent 569e937e01
commit ea2e7ce5d0
1 changed files with 6 additions and 3 deletions
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9
kernel/bpf/verifier.c
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@ -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;