Messages in this thread | | | Date | Mon, 15 Jun 2020 11:21:08 -0700 | From | Kees Cook <> | Subject | Re: [PATCH] security: fix the key_permission LSM hook function type |
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On Mon, Jun 15, 2020 at 11:12:32AM -0700, Sami Tolvanen wrote: > Commit 8c0637e950d6 ("keys: Make the KEY_NEED_* perms an enum rather than > a mask") changed the type of the key_permission callback functions, but > didn't change the type of the hook, which trips indirect call checking with > Control-Flow Integrity (CFI). This change fixes the issue by changing the > hook type to match the functions. > > Fixes: 8c0637e950d6 ("keys: Make the KEY_NEED_* perms an enum rather than a mask") > Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Thanks for fixing this!
Acked-by: Kees Cook <keescook@chromium.org>
I wonder if there is any compiler option we can turn on to catch the implicit enum/int casting that would help for these kinds of things without absolutely exploding the build warnings.
I see -Wenum-conversion, but that seems to be between enums, not between int.
I see this, but it's external: https://noamlewis.wordpress.com/2017/10/05/type-safe-enums-in-c-using-a-clang-plugin/
-Kees
> --- > include/linux/lsm_hook_defs.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h > index 6791813cd439..24f6683f1cfc 100644 > --- a/include/linux/lsm_hook_defs.h > +++ b/include/linux/lsm_hook_defs.h > @@ -360,7 +360,7 @@ LSM_HOOK(int, 0, key_alloc, struct key *key, const struct cred *cred, > unsigned long flags) > LSM_HOOK(void, LSM_RET_VOID, key_free, struct key *key) > LSM_HOOK(int, 0, key_permission, key_ref_t key_ref, const struct cred *cred, > - unsigned perm) > + enum key_need_perm need_perm) > LSM_HOOK(int, 0, key_getsecurity, struct key *key, char **_buffer) > #endif /* CONFIG_KEYS */ > > > base-commit: b3a9e3b9622ae10064826dccb4f7a52bd88c7407 > -- > 2.27.0.290.gba653c62da-goog >
-- Kees Cook
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