Reading privileged memory with a side-channel

Re:Reading privileged memory with a side-channel by Pyxl101 on Wednesday January 03, 2018 @09:13PM (#16067435)

Do you need root or comparable privileges to take advantage of BPF? I did not think that was the case. My understanding was that BPF code executes within the kernel.

BPF is employed by the `bpf()` syscall for socket packet filtering, as well as by `seccomp` itself for its syscall filtering. Is this threat vector not available to untrusted processes?

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Re:Reading privileged memory with a side-channel by language on Wednesday January 03, 2018 @10:08PM (#16067714)

iirc I think that the BPF JIT is disabled by default? Your kernel might be compiled with `CONFIG_BPF_JIT`, but I think the sysctl knob (`bpf_jit_enable`) is set to 0 by default. Also there's a sysctl for unprivileged BPF called `unprivileged_bpf_disabled`. On my system it seems to default to 0.

https://elixir.free-electrons.com/linux/v4.15-rc6/source/ker...

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