Messages in this thread | | | From | Kees Cook <> | Date | Sat, 15 Sep 2018 18:47:30 -0700 | Subject | Re: [PATCH 11/18] LSM: Lift LSM selection out of individual LSMs |
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On Sat, Sep 15, 2018 at 6:32 PM, Jann Horn <jannh@google.com> wrote: > On Sun, Sep 16, 2018 at 3:14 AM Kees Cook <keescook@chromium.org> wrote: >> In order to adjust LSM selection logic in the future, this moves the >> selection logic up out of the individual LSMs, making their init functions >> only run when actually enabled. > [...] >> +/* Is an LSM allowed to be enabled? */ >> +static bool __init lsm_enabled(struct lsm_info *lsm) >> +{ >> + /* Report explicit disabling. */ >> + if (lsm->enabled && !*lsm->enabled) { >> + pr_info("%s disabled with boot parameter\n", lsm->name); >> + return false; >> + } >> + >> + /* If LSM isn't exclusive, ignore exclusive LSM selection rules. */ >> + if (lsm->type != LSM_TYPE_EXCLUSIVE) >> + return true; >> + >> + /* Disabled if another exclusive LSM already selected. */ >> + if (exclusive) >> + return false; > > What is this check for, given that you have the strcmp() just below > here? From a quick look, it (together with everything else that > touches the "exclusive" variable) seems superfluous to me, unless > there are two LSMs with the same name (which really shouldn't happen, > right?). > >> + /* Disabled if this LSM isn't the chosen one. */ >> + if (strcmp(lsm->name, chosen_lsm) != 0) >> + return false; >> + >> + return true; >> +}
Mainly it's for composition with later patches where the name check is moved. It seemed easier to explain the logical progression with the hunk here.
-Kees
-- Kees Cook Pixel Security
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