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=9oqza6...@mail.gmail.com] but Kees and Casey seem to prefer the current approach.
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