On Mon, Jun 29, 2020 at 5:28 PM Alexei Starovoitov
[off-list ref] wrote:

On Thu, Jun 18, 2020 at 3:33 PM Andrii Nakryiko
[off-list ref] wrote:

quoted

quoted

+ *
+ * int bpf_copy_from_user(void *dst, u32 size, const void *user_ptr)

Can we also add bpf_copy_str_from_user (or bpf_copy_from_user_str,
whichever makes more sense) as well?

Those would have to wait. I think strings need better long term design.
That would be separate patches.

I agree that it would be nice to have better support for strings, long
term, but that's beside the point.

I think bpf_copy_from_user_str() is a must have right now as a
sleepable counterpart to bpf_probe_read_user_str(), just like
bpf_copy_from_user() is a sleepable variant of bpf_probe_read_user().
Look at progs/strobemeta.h, it does bpf_probe_read_user_str() to get
user-space zero-terminated strings. It's well defined interface and
behavior. There is nothing extra needed beyond a sleepable variant of
bpf_probe_read_user_str() to allow Strobemeta reliably fetch data from
user-space from inside a sleepable BPF program.