Bug 2084334

The issue seems to be with a database that is migrated from dbm to sqlite.

The attached script generates a self-signed CA and 100 server certificates.

To run it:

$ mkdir /tmp/nssdb
$ bash gencert dbm:/tmp/nssdb
$ echo httptest > /tmp/nssdb/passwd

Listing all the keys takes less than a second:

$ time certutil -K -d dbm:/tmp/nssdb -f /tmp/nssdb/passwd
real    0m0.559s
user    0m0.444s
sys     0m0.086s

Upgrade it to sqlite:

$ certutil -d sql:/tmp/nssdb/ -N -f /tmp/nssdb/passwd  -@ /tmp/nssdb/passwd

Same listing of keys:

$ time certutil -K -d dbm:/tmp/nssdb -f /tmp/nssdb/passwd
real    0m46.905s
user    0m45.400s
sys     0m0.177s

Now if we create the database directly as sqlite the timing is more in line with dbm:

$ mkdir /tmp/nssdb2
$ bash gencert sql:/tmp/nssdb2
$ echo httptest > /tmp/nssdb2/passwd

And list the keys:
$ time certutil -K -d sql:/tmp/nssdb2 -f /tmp/nssdb2/passwd

real    0m0.742s
user    0m0.581s
sys     0m0.032s

Also worth mentioning that generating the sqlite database using gencert takes significantly longer than the dbm database. It's plausible that entropy on this VM is simply exhausted.

Reproduced with nss-3.67.0-6.el8_4.x86_64

Created attachment 1878803 [details]
Script to generate a CA and 100 server certificates

Changing component to nss for review.

This is almost certainly caused by the cache trashing bug when we added integrity to AES. The issue is the key for the decrypt and the key for the integrity check are different, and they would throuh each other out of the cache, so you ended up doing the PBE for every key. (The issue is seen with databases with large numbers of private keys). Does this happen on RHEL-9? If not it should be fixed on the next NSS rebase next month.

Rob, can you verify that this does not happen on fedora (I also think RHEL-9 has the appropriate patches as well).

bob

dbm isn't allowed in Fedora since I think Fedora 32 or 33.

$ certutil -N -d dbm:/tmp/nssdb
certutil: function failed: SEC_ERROR_LEGACY_DATABASE: The certificate/key database is in an old, unsupported format.

Oh, I thought that it was just that the database on sqlite was being slow. Hmmm If you copy the database dbm upgraded database to rhel-9 or fedora, is it still slow?

There is an upstream bug that was fixed where if you have 100 or so keys, sqlite was really slow listing them. The fix for this is not in RHEL-8. I wonder why we aren't tripping over this when you create the database in sqlite?

bob

It takes about 4s to list the 100 keys from the same database using nss-3.71.0-1.fc33.x86_64

$ time certutil -K -d sql:/tmp/nssdb/ -f /tmp/nssdb/passwd
real    0m4.155s
user    0m4.102s
sys     0m0.031s

Thanks Rob. That looks like there may be multiple issues, the main one being cache thrashing.

slight error in comment 1

> Upgrade it to sqlite:
>
> $ certutil -d sql:/tmp/nssdb/ -N -f /tmp/nssdb/passwd  -@ /tmp/nssdb/passwd
>
> Same listing of keys:
>
> $ time certutil -K -d dbm:/tmp/nssdb -f /tmp/nssdb/passwd

This last line should be:

$ time certutil -K -d sql:/tmp/nssdb -f /tmp/nssdb/passwd

> Also worth mentioning that generating the sqlite database using gencert takes significantly longer than the dbm database. 
> It's plausible that entropy on this VM is simply exhausted.

No keygen against the sql database definitely takes longer I can see that in both the rhel-8 certutil and my current upsteam certutil.

So the issuer is the CERT_USERDB bit in the trust, fools the legacydb (dbm) into presenting trust objects that are actually empty trust objects. Since NSS checks the integrity of trust objects if you've logged in (which you have to to display the keys), it takes quite some time to display each cert.

There are two fixes: 1) we can skip the integrity check if the value we are checking is the value we would default to if there wasn't any trust value (which you get when the integrity check fails. This speeds up the listing of the databases with these dead trust values by about 10x. 2) Fix dbm to to correctly skip cert trust objects with the CERTDB_USER bit and nothing else. This will fix the case the created the bad databases, but won't fix the displaying of the bad databases.

NSS 3.79 shipped today, so it won't be upstreamed in time to patch this there. We'll carry the patch until the next release of NSS.

RHEL 8.7 contains nss-3.79.0-10.el8_6.