Messages in this thread |  | | Subject | Re: [PATCH v1] LSM: Enable multiple calls to security_add_hooks() for the same LSM | From | Mickaël Salaün <> | Date | Sun, 30 Apr 2017 11:35:26 +0200 |
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On 30/04/2017 04:11, Tetsuo Handa wrote: > Casey Schaufler wrote: >> On 4/29/2017 12:02 PM, Mickael Salaun wrote: >>> Check if the registering LSM already registered hooks just before. This >>> enable to split hook declarations into multiple files without >>> registering multiple time the same LSM name, starting from commit >>> d69dece5f5b6 ("LSM: Add /sys/kernel/security/lsm"). >> >> What's special about the previous registration? Keep it >> simple and check it the name is already anywhere on the >> list and only add it if it's not already there. I don't >> see advantage to: >> >> % cat /sys/kernel/security/lsm >> capability,yama,spiffy,selinux,spiffy >> >> over >> % cat /sys/kernel/security/lsm >> capability,yama,spiffy,selinux >>
That was my first though, but then I realized that I don't see any use case where an LSM would register hooks interleaved with other LSM. I find the current approach simpler because we only search from the end of the string and we do not handle special cases (e.g. matching only a sub-name). Moreover, this approach respects the semantic describe in Documentation/security/LSM.txt: "The list reflects the order in which checks are made".
> > - if (lsm_append(lsm, &lsm_names) < 0) > + if (lsm && lsm_append(lsm, &lsm_names) < 0) > > in security_add_hooks()? >
That was considered [https://lkml.kernel.org/r/CAGXu5jJCvJ6-uZ=Kfhh3xD7UvaY+G99e9NXFMzvi=9OQzA6Ecg@mail.gmail.com] but Kees and Casey seem to prefer the current approach.
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