Re: [PATCH v2 4/4] bpf: export bpf_jit_current

Le 13/10/2021 à 10:35, Lorenz Bauer a écrit :

On Tue, 12 Oct 2021 at 17:29, Nicolas Dichtel [off-list ref] wrote:

quoted

Le 12/10/2021 à 15:59, Lorenz Bauer a écrit :

quoted

Expose bpf_jit_current as a read only value via sysctl.

Signed-off-by: Lorenz Bauer <redacted>
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[snip]

quoted

+     {
+             .procname       = "bpf_jit_current",
+             .data           = &bpf_jit_current,
+             .maxlen         = sizeof(long),
+             .mode           = 0400,

Why not 0444 ?

This mirrors what the other BPF related sysctls do, which only allow
access from root with CAP_SYS_ADMIN. I'd prefer 0444 as well, but
Daniel explicitly locked down these sysctls in
2e4a30983b0f9b19b59e38bbf7427d7fdd480d98.

Even after this patch, bpf_jit_enable is 0644.

In fact, if you have CAP_BPF or CAP_SYS_ADMIN, this value has no impact for your
programs. But I you don't have one of these capabilities, it may be rejected,
but you cannot read these values, which help to understand why.


Regards,
Nicolas