On 19/03/2021 19:40, Kees Cook wrote: > On Tue, Mar 16, 2021 at 09:42:42PM +0100, Mickaël Salaün wrote: >> From: Mickaël Salaün <mic@xxxxxxxxxxxxxxxxxxx> >> >> A Landlock ruleset is mainly a red-black tree with Landlock rules as >> nodes. This enables quick update and lookup to match a requested >> access, e.g. to a file. A ruleset is usable through a dedicated file >> descriptor (cf. following commit implementing syscalls) which enables a >> process to create and populate a ruleset with new rules. >> >> A domain is a ruleset tied to a set of processes. This group of rules >> defines the security policy enforced on these processes and their future >> children. A domain can transition to a new domain which is the >> intersection of all its constraints and those of a ruleset provided by >> the current process. This modification only impact the current process. >> This means that a process can only gain more constraints (i.e. lose >> accesses) over time. >> >> Cc: James Morris <jmorris@xxxxxxxxx> >> Cc: Jann Horn <jannh@xxxxxxxxxx> >> Cc: Kees Cook <keescook@xxxxxxxxxxxx> >> Signed-off-by: Mickaël Salaün <mic@xxxxxxxxxxxxxxxxxxx> >> Acked-by: Serge Hallyn <serge@xxxxxxxxxx> >> Link: https://lore.kernel.org/r/20210316204252.427806-3-mic@xxxxxxxxxxx > > (Aside: you appear to be self-adding your Link: tags -- AIUI, this is > normally done by whoever pulls your series. I've only seen Link: tags > added when needing to refer to something else not included in the > series.) It is an insurance to not lose history. :) > >> [...] >> +static void put_rule(struct landlock_rule *const rule) >> +{ >> + might_sleep(); >> + if (!rule) >> + return; >> + landlock_put_object(rule->object); >> + kfree(rule); >> +} > > I'd expect this to be named "release" rather than "put" since it doesn't > do any lifetime reference counting. It does decrement rule->object->usage . > >> +static void build_check_ruleset(void) >> +{ >> + const struct landlock_ruleset ruleset = { >> + .num_rules = ~0, >> + .num_layers = ~0, >> + }; >> + >> + BUILD_BUG_ON(ruleset.num_rules < LANDLOCK_MAX_NUM_RULES); >> + BUILD_BUG_ON(ruleset.num_layers < LANDLOCK_MAX_NUM_LAYERS); >> +} > > This is checking that the largest possible stored value is correctly > within the LANDLOCK_MAX_* macro value? Yes, there is builtin checks for all Landlock limits. > >> [...] > > The locking all looks right, and given your test coverage and syzkaller > work, it's hard for me to think of ways to prove it out any better. :) Thanks! > > Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> > >
