> Am 15.08.2019 um 22:35 schrieb Andrey Ignatov <rdna@xxxxxx>:
>
>> @@ -1344,20 +1379,26 @@ static size_t probe_prog_length(const struct bpf_insn *fp)
>> static int fixup_sysctl_value(const char *buf, size_t buf_len,
>> struct bpf_insn *prog, size_t insn_num)
>> {
>> - uint32_t value_num = 0;
>> + uint64_t value_num = 0;
>> uint8_t c, i;
>>
>> if (buf_len > sizeof(value_num)) {
>> log_err("Value is too big (%zd) to use in fixup", buf_len);
>> return -1;
>> }
>> + if (prog[insn_num].code != (BPF_LD | BPF_DW | BPF_IMM)) {
>> + log_err("Can fixup only BPF_LD_IMM64 insns");
>> + return -1;
>> + }
>>
>> for (i = 0; i < buf_len; ++i) {
>> c = buf[i];
>> value_num |= (c << i * 8);
>> }
>> + value_num = __bpf_le64_to_cpu(value_num);
>>
>> - prog[insn_num].imm = value_num;
>> + prog[insn_num].imm = (__u32)value_num;
>> + prog[insn_num + 1].imm = (__u32)(value_num >> 32);
>>
>> return 0;
>> }
>> @@ -1499,6 +1540,7 @@ static int run_test_case(int cgfd, struct sysctl_test *test)
>> goto err;
>> }
>>
>> + errno = 0;
>
> Yeah, access_sysctl() can return -1 w/o affecting errno, did it cause a
> problem, or you set it just in case?
It's actually for another use case: if access_sysctl() unexpectedly
returns 0, log_err() will misleadingly print a "random" errno. With this
change, it would print "Unexpected success: errno: None", which makes
sense to me.
