0b5acde4c4
AT-AT needs to maintain a key-value CRL cache where each key is the DER byte-string of the issuer and the value is a dictionary of the CRL file path and expiration. This way when it checks a client certificate, it can load the correct CRL by comparing the issuers. This is preferable to loading all of the CRLs in-memory. However, it still requires that AT-AT load and parse each CRL when the application boots. Because of the size of the CRLs and their parsed, in-memory size, this leads to the application spiking to use nearly 900MB of memory (resting usage is around 50MB). This change introduces a small function to ad-hoc parse the CRL and obtain the information in the CRL we need: the issuer and the expiration. It does this by reading the CRL byte-by-byte until it reaches the ASN1 sequence that corresponds to the issuer, and then looks ahead to find the nextUpdate field (i.e., the expiration date). The CRLCache class uses this function to build its cache and JSON-serializes the cache to disk. If another AT-AT application process finds the serialized version, it will load that copy instead of rebuilding it. It also entails a change to the function signature for the init method of CRLCache: now it expects the CRL directory as its second argument, instead of a list of locations. The Python script invoked by `script/sync-crls` will rebuild the location cache each time it's run. This means that when the Kubernetes CronJob for CRLs runs, it will refresh the cache each time. When a new application container boots, it will get the refreshed cache. This also adds a nightly CircleCI job to sync the CRLs and test that the ad-hoc parsing function returns the same result as a proper parsing using the Python cryptography library. This provides extra insurance that the function is returning correct results on real data.
Regenerating Fixture Certificates
You don't need to keep the key file generated by this process.
- Certificate with an email as subjectAltName:
openssl req -x509 \
-newkey rsa:4096 \
-sha256 \
-nodes \
-days 3650 \
-keyout _foo.key \
-out artgarfunkel@uso.mil.crt \
-subj "/CN=GARFUNKEL.ART.G.5892460358" \
-extensions SAN \
-config <(cat /etc/ssl/openssl.cnf; echo '[SAN]'; echo 'subjectAltName=email:artgarfunkel@uso.mil')
- Certificate with a DNS name as subjectAltName:
openssl req -x509 \
-newkey rsa:4096 \
-sha256 \
-nodes \
-days 3650 \
-keyout _foo.key \
-out no-email.crt \
-subj "/CN=GARFUNKEL.ART.G.5892460358" \
-extensions SAN \
-config <(cat /etc/ssl/openssl.cnf; echo '[SAN]'; echo 'subjectAltName=DNS:artgarfunkel.com')
- Certificate with no subjectAltName:
openssl req -x509 \
-newkey rsa:4096 \
-sha256 \
-nodes \
-days 3650 \
-keyout _foo.key \
-out no-san.crt \
-subj "/CN=GARFUNKEL.ART.G.5892460358"