linux-kernel - Re: bpf: test_verifier: sanitation: alu with different scalars

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Date:   Fri, 26 Jul 2019 13:41:41 +0300
From:   Yauheni Kaliuta <yauheni.kaliuta@...hat.com>
To:     Daniel Borkmann <daniel@...earbox.net>
Cc:     linux-kernel@...r.kernel.org, Jiri Olsa <jolsa@...hat.com>,
        Jiri Benc <jbenc@...hat.com>
Subject: Re: bpf: test_verifier: sanitation: alu with different scalars

Hi, Daniel,

On Tue, Jun 25, 2019 at 12:39 PM Daniel Borkmann <daniel@...earbox.net> wrote:
>
> On 06/25/2019 10:29 AM, Yauheni Kaliuta wrote:
> > Hi!
> >
> > I'm wondering, how the sanitaion tests (#903 5.2-rc6 for example)
> > are supposed to work on BE arches:
> >
> > {
> >       "sanitation: alu with different scalars 1",
> >       .insns = {
> >       BPF_MOV64_IMM(BPF_REG_0, 1),
> >       BPF_LD_MAP_FD(BPF_REG_ARG1, 0),
> >       BPF_MOV64_REG(BPF_REG_ARG2, BPF_REG_FP),
> >       BPF_ALU64_IMM(BPF_ADD, BPF_REG_ARG2, -16),
> >       BPF_ST_MEM(BPF_DW, BPF_REG_FP, -16, 0),
> >       BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
> >       BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),
> >       BPF_EXIT_INSN(),
> >       BPF_LDX_MEM(BPF_B, BPF_REG_1, BPF_REG_0, 0),
> >
> > reads one byte 0 on BE and 28 on LE (from ->index) since
> >
> >       struct test_val {
> >               unsigned int index;
> >               int foo[MAX_ENTRIES];
> >       };
> >
> >         struct test_val value = {
> >               .index = (6 + 1) * sizeof(int),
> >               .foo[6] = 0xabcdef12,
> >       };
> >
> >       BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 3),
> >
> > So different branches are taken depending of the endianness.
> >
> >       BPF_MOV64_IMM(BPF_REG_2, 0),
> >       BPF_MOV64_IMM(BPF_REG_3, 0x100000),
> >       BPF_JMP_A(2),
> >       BPF_MOV64_IMM(BPF_REG_2, 42),
> >       BPF_MOV64_IMM(BPF_REG_3, 0x100001),
> >       BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_3),
> >       BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
> >       BPF_EXIT_INSN(),
> >       },
> >       .fixup_map_array_48b = { 1 },
> >       .result = ACCEPT,
> >       .retval = 0x100000,
> > },
>
> Let me get my hands on a s390x box later today and get back to you.

Any progress with that?

-- 
WBR, Yauheni