On 2022-11-07 17:20+0100, Mickaël Salaün wrote: > On 07/11/2022 16:55, Thomas Weißschuh wrote: > > On 2022-11-07 14:12+0100, Mickaël Salaün wrote: > > > This is a follow-up of > > > https://lore.kernel.org/r/c8c65713-5cda-43ad-8018-20f2e32e4432@xxxxxxxx > > > > > > Added Jarkko, Mark Pearson, Eric Snowberg and more ML in Cc. > > > > > > > > > On 04/11/2022 02:47, Thomas Weißschuh wrote: > > > > When the blacklist keyring was changed to allow updates from the root > > > > user it gained an ->update() function that disallows all updates. > > > > When the a hash is blacklisted multiple times from the builtin or > > > > firmware-provided blacklist this spams prominent logs during boot: > > > > > > > > [ 0.890814] blacklist: Problem blacklisting hash (-13) > > > > > > > > As all these repeated calls to mark_raw_hash_blacklisted() would create > > > > the same keyring entry again anyways these errors can be safely ignored. > > > > > > These errors can indeed be safely ignored, however they highlight issues > > > with some firmware vendors not checking nor optimizing their blocked hashes. > > > This raises security concerns, and it should be fixed by firmware vendors. > > > > Thanks, I was not aware that these are worth fixing. > > > > > > Fixes: 6364d106e041 ("certs: Allow root user to append signed hashes to the blacklist keyring") > > > > Signed-off-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx> > > > > --- > > > > certs/blacklist.c | 4 +++- > > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/certs/blacklist.c b/certs/blacklist.c > > > > index 41f10601cc72..5f7f2882ced7 100644 > > > > --- a/certs/blacklist.c > > > > +++ b/certs/blacklist.c > > > > @@ -191,7 +191,9 @@ static int mark_raw_hash_blacklisted(const char *hash) > > > > BLACKLIST_KEY_PERM, > > > > KEY_ALLOC_NOT_IN_QUOTA | > > > > KEY_ALLOC_BUILT_IN); > > > > - if (IS_ERR(key)) { > > > > + > > > > + /* Blacklisting the same hash twice fails but would be idempotent */ > > > > + if (IS_ERR(key) && PTR_ERR(key) != -EACCES) { > > > > > > We should not hide EACCES errors. This logs issues, which is correct for > > > duplicate hashes, and can help firmware vendors to fix their database. I'd > > > really like to see a different log message instead: change the duplicate > > > entry error code from EACCES to EEXIST, and call pr_warn for this specific > > > case. > > > > Returning EACCES would require some deeper changes to how the keyring is set up > > I guess you meant EEXIST? Indeed, sorry. > > or even changes to the keyring core itself to introduce a key_create() (without > > update) function. > > > > Is this something you would take a look at, or should I try to do it? > > (I have no previous knowledge about the keyring subsystem) > > Please take a look. I think it should not be too complex. Will do. My plan is to create a new function key_create() that does takes the core logic of key_create_or_update() and fails with EEXIST if needed. > > In any case it probably would also be good to log the problematic hashes > > themselves, so users can properly report the issue to their firmware vendors. > > Agree I'll send a patch for that, too. As for this patch's Fixes-tag, it could refer to either the commit that introduced the logging in the first place or the one that actively started to trigger it: * 734114f8782f ("KEYS: Add a system blacklist keyring") * 6364d106e041 ("certs: Allow root user to append signed hashes to the blacklist keyring") Personally I'd tend to use the latter. > > > > pr_err("Problem blacklisting hash (%ld)\n", PTR_ERR(key)); > > > > return PTR_ERR(key); > > > > } > > > > > > > > base-commit: ee6050c8af96bba2f81e8b0793a1fc2f998fcd20
