Re: [PATCH bpf-next v4 2/4] selftests/bpf: Update EFAULT {g,s}etsockopt selftests

[Martin KaFai Lau <martin.lau@linux.dev>]

On 5/4/23 11:43 AM, Stanislav Fomichev wrote:
> @@ -648,6 +676,49 @@ static struct sockopt_test {
>   
>   		.error = EFAULT_SETSOCKOPT,
>   	},
> +	{
> +		.descr = "setsockopt: ignore >PAGE_SIZE optlen",
> +		.insns = {
> +			/* write 0xFF to the first optval byte */
> +
> +			/* r6 = ctx->optval */
> +			BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1,
> +				    offsetof(struct bpf_sockopt, optval)),
> +			/* r2 = ctx->optval */
> +			BPF_MOV64_REG(BPF_REG_2, BPF_REG_6),
> +			/* r6 = ctx->optval + 1 */
> +			BPF_ALU64_IMM(BPF_ADD, BPF_REG_6, 1),
> +
> +			/* r7 = ctx->optval_end */
> +			BPF_LDX_MEM(BPF_DW, BPF_REG_7, BPF_REG_1,
> +				    offsetof(struct bpf_sockopt, optval_end)),
> +
> +			/* if (ctx->optval + 1 <= ctx->optval_end) { */
> +			BPF_JMP_REG(BPF_JGT, BPF_REG_6, BPF_REG_7, 1),
> +			/* ctx->optval[0] = 0xF0 */
> +			BPF_ST_MEM(BPF_B, BPF_REG_2, 0, 0xFF),
> +			/* } */
> +
> +			BPF_MOV64_IMM(BPF_REG_0, 1),
> +			BPF_EXIT_INSN(),
> +		},
> +		.attach_type = BPF_CGROUP_SETSOCKOPT,
> +		.expected_attach_type = BPF_CGROUP_SETSOCKOPT,
> +
> +		.set_level = SOL_IP,
> +		.set_optname = IP_TOS,
> +		.set_optval = { 1 << 3 },
> +		.set_optlen = PAGE_SIZE + 1,
> +
> +		.get_level = SOL_IP,
> +		.get_optname = IP_TOS,
> +#if __BYTE_ORDER == __LITTLE_ENDIAN
> +		.get_optval = { 1 << 3, 0, 0, 0 }, /* the changes are ignored */
> +#else
> +		.get_optval = { 0, 0, 0, 1 << 3 }, /* the changes are ignored */

This fails in s390 (big endian?): 
https://github.com/kernel-patches/bpf/actions/runs/4895136324/jobs/8740562449

I don't think it needs special treatment here on different __BYTE_ORDER. Other 
tests in this file also don't do that.

> +#endif
> +		.get_optlen = 4,
> +	},