On Fri, Jun 17, 2022 at 2:11 AM Roberto Sassu <roberto.sassu@xxxxxxxxxx> wrote: > > > From: Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> > > Sent: Friday, June 17, 2022 5:46 AM > > Adding in CC the keyring mailing list and David. > > Sort summary: we are adding an eBPF helper, to let eBPF programs > verify PKCS#7 signatures. The helper simply calls verify_pkcs7_signature(). > > The problem is how to pass the key for verification. > > For hardcoded keyring IDs, it is easy, pass 0, 1 or 2 for respectively > the built-in, secondary and platform keyring. > > If you want to pass another keyring, you need to do a lookup, > which returns a key with reference count increased. > > While in the kernel you can call key_put() to decrease the > reference count, that is not guaranteed with an eBPF program, > if the developer forgets about it. What probably is necessary, > is to add the capability to the verifier to check whether the > reference count is decreased, or adding a callback mechanism > to call automatically key_put() when the eBPF program is > terminated. Nothing special here. See acquire/release logic in the verifier and relevant helpers. Like bpf_sk_lookup_tcp and others. > Is there an alternative solution? > > Thanks > > Roberto > > HUAWEI TECHNOLOGIES Duesseldorf GmbH, > HRB 56063 Managing Director: Li Peng, Yang Xi, Li He Please remove this footer from your emails.
