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d02ebc922c
* feat: Change Postfix smtpd_tls key and cert files to chain_files Since Postfix 3.4, `smtpd_tls_cert_file` and `smtpd_tls_key_file` have been deprecated in favor of `smtpd_tls_chain_files` which supports a list of values where a single or sequence of file paths provide a private key followed by it's certificate chain. * feat: Dual certificate support `smtpd_tls_chain_files` allows for multiple key+cert bundles so that you can provide different key types, such as ECDSA and RSA. To maintain compatibility with the current CERT/KEY ENV vars only a 2nd certificate is supported. Since Dovecot 2.2.31 a related feature is also available, but it is limited to only providing one alternative certificate via separate cert and key settings. --- This feature enables support for multiple certificates, eg for serving modern ECDSA certs with RSA as fallback. * chore: Refactor variable names to meet style guide Improved some comments too. * chore: Have function definitions respect style guide * chore: Minor edits to comments * chore: Expand on comments for maintenance, alert of insecure config When `SSL_TYPE` isn't properly setup, we're still offering SSL connections but not warning in logs about the insecurity of such, or why a misconfiguration may have occurred. This commit more clearly communicates to the user that they should look into the issue before considering deploying to production. The `TODO` comments communicate to any future maintainer to consider treating these improper configs as disabling TLS instead. * fix: Use `snakeoil` cert I mistakenly thought this was placeholder text, which broke some tests. This adds the two files in the correct order (private key followed by cert/chain), to fix that issue. * fix: Disable alt cert for Dovecot if necessary Certain scenarios may persist state of previously configured alt cert via ENV vars that are removed from a future run. If the config is not reset to original immutable state, this will correctly disable the config from using alt cert unintentionally. * fix: Satisfy ShellCheck lint By switching from string var to array / list expansion, this better stores the extracted result and applies it in a manner that ShellCheck linting approves, removing the need to disable the rule. * feat: Support dual cert test Few tweaks to the test script allows re-purposing it for covering dual cert support as well. * chore: Rearranged cert and key lines A little reorganization, mostly placing private key ahead of related cert lines. * chore: Refactor `_set_certificate` This should make the parameters a little less confusing. Previously was 3 parameters, but the Postfix parameter (1st) may look like two variables if you don't pay attention to the surrounding quotes; while the Dovecot parameters (2nd + 3rd) would have an opposing order. There was also a variant where the `FULLKEYCHAIN` var was passed in three times. Now it's two params, with the 2nd param as an optional one. If the 2nd param is provided, then the two params are in the order of private key then certificate, otherwise if only a single parameter it's a single PEM file with the full cert chain and private key bundled. This avoids implying that Postfix and Dovecot might use different files. * chore: Document current state of `SSL_TYPE` logic better Inlined for the benefit of anyone else maintaining this section if I'm unable to address the concerns within my own time. * docs: ENV vars `TLS_LEVEL=old` isn't in the codebase anymore, not likely to be relevant to retain. No point in documenting what is considered invalid / unsupported config value in the first place for `SSL_TYPE`. `SSL_TYPE=manual` was missing documentation for both related file path ENV vars, they've been added along with their alt fallback variants. * chore: Update Dovecot LMTP SSL test config Not sure how relevant this is, the file isn't complete sync with the main dovecot `10-ssl.conf` config, adding the support just in case. * chore: Rename `FULLKEYCHAIN` to avoid confusion There doesn't appear to be a standardized name for this type of file bundle, and `keychain` may be misleading (fullkeychain often provides macOS keychain results on search engines). Opting for a more explicit `KEY_WITH_FULLCHAIN` name instead. * fix: Invalid var name `_set_certificate` refactor commit accidentally changed a var name and committed that breaking the dual cert support (thanks tests!). * test: Refactor `mail_ssl_manual.bats` Proper test return values instead of `wc -l` based checking. Tests with dual cert support active, tests that feature (to better detect failure case. Third test case was unable to verify new self-signed certificate, added new certs signed with self-signed root CA. Adjusted openssl `CApath` parameter to use `CAfile` instead as `letsencrypt` cert was replaced thus CA cert is missing from the system trust store. * test: Properly check for files in `mail_ssl_manual.bats` Fixes lint error. Also realized I was accidentally asserting a file exists in the test environment, not within the container. Resolved that and also added an additional test case to ensure the ENV var files are valid when passed in, in the event a change misconfigures them and that the issue is identified earlier. * chore: Apply PR review feedback Better format some strings that had mixed quotes when they weren't necessary. Additionally DRYed up the config path for Postfix and Dovecot within the `_setup_ssl` method. Co-authored-by: Georg Lauterbach <infrastructure@itbsd.com> |
||
|---|---|---|
| .. | ||
| with_ca | ||
| cert.ecdsa.pem | ||
| cert.rsa.pem | ||
| key.ecdsa.pem | ||
| key.rsa.pem | ||
| README.md | ||
| testssl.txt | ||
Testing certificates for TLS
Use these certificates for any tests that require a certificate during a test. DO NOT USE IN PRODUCTION.
These certificates for usage with TLS have been generated via the Smallstep step certificate CLI tool. They have a duration of 10 years and are valid for the SAN example.test or it's mail subdomain.
Certificate Details sections are the output of: step certificate inspect cert.<key type>.pem.
RSA (2048-bit) - self-signed:
step certificate create "Smallstep self-signed" cert.rsa.pem key.rsa.pem \
--no-password --insecure \
--profile self-signed --subtle \
--not-before "2021-01-01T00:00:00+00:00" \
--not-after "2031-01-01T00:00:00+00:00" \
--san "example.test" \
--san "mail.example.test" \
--kty RSA --size 2048
Certificate Details:
Certificate:
Data:
Version: 3 (0x2)
Serial Number: 208627341009417536895802991697858158387 (0x9cf42a11521763a5a0fbd1cedb085f33)
Signature Algorithm: SHA256-RSA
Issuer: CN=Smallstep self-signed
Validity
Not Before: Jan 1 00:00:00 2021 UTC
Not After : Jan 1 00:00:00 2031 UTC
Subject: CN=Smallstep self-signed
Subject Public Key Info:
Public Key Algorithm: RSA
Public-Key: (2048 bit)
Modulus:
e2:78:fa:af:1b:82:ee:92:8c:b6:9b:96:ee:a7:4f:
b8:dd:72:ec:c6:85:97:a8:53:c0:ad:0c:04:c9:23:
5d:3e:f5:1a:ce:78:b7:14:fd:61:53:1e:51:03:54:
64:60:3c:87:38:c9:fc:ec:55:8e:c0:dd:82:8c:ac:
d9:e9:b8:ee:37:df:95:60:d9:f2:02:f6:21:04:e0:
af:d2:c5:1a:b6:3e:5f:dc:3a:31:b8:e6:c7:37:8b:
7a:53:54:b1:21:61:34:31:05:aa:6f:28:88:89:2d:
ac:43:f8:4f:b0:e7:57:17:fe:b6:4d:b3:7c:0e:f4:
34:58:1c:b7:06:e9:33:13:d3:2a:68:eb:41:c3:5c:
cf:a9:f1:76:b4:41:9e:cd:86:6a:4a:80:6b:05:cd:
5c:0f:1a:6d:f6:8d:ed:50:a2:b5:f7:97:00:75:1b:
36:9f:e8:68:e7:43:d4:1c:cc:7e:d3:03:e0:c5:be:
54:ab:e9:e4:dc:53:36:6c:b2:46:fb:72:bd:26:e7:
9b:c6:45:a9:be:4a:e3:10:b8:80:55:ee:28:63:09:
09:60:9c:fb:57:f4:c7:36:8f:09:39:32:9d:26:92:
4b:78:51:9c:eb:bc:74:61:ec:80:6e:73:59:5d:52:
f2:02:95:24:f7:47:9d:6a:b2:b3:17:35:9d:48:58:
81
Exponent: 65537 (0x10001)
X509v3 extensions:
X509v3 Key Usage: critical
Digital Signature, Key Encipherment
X509v3 Extended Key Usage:
Server Authentication, Client Authentication
X509v3 Subject Key Identifier:
05:AC:63:51:E2:44:A1:46:F8:08:86:D9:EF:69:32:B2:89:6D:DA:CE
X509v3 Subject Alternative Name:
DNS:example.test, DNS:mail.example.test
Signature Algorithm: SHA256-RSA
50:47:7b:59:26:9d:8d:f7:e4:dc:03:94:b0:35:e4:03:b7:94:
16:7e:b6:79:c5:bb:e7:61:db:ca:e6:22:cc:c8:a0:9f:9d:b0:
7c:12:43:ec:a7:f3:fe:ad:0a:44:69:69:7f:c7:31:f7:3f:e8:
98:a7:37:43:bd:fb:5b:c6:85:85:91:dc:29:23:cb:6b:a9:aa:
f0:f0:62:79:ce:43:8c:5f:28:49:ee:a1:d4:16:67:6b:59:c3:
15:65:e3:d3:3b:35:da:59:35:33:2a:5e:8a:59:ff:14:b9:51:
a5:8e:0b:7c:1b:a1:b1:f4:89:1a:3f:2f:d7:b1:8d:23:0a:7a:
79:e1:c2:03:b5:2f:ee:34:16:a9:67:27:b6:10:67:5d:f4:1d:
d6:b3:e0:ab:80:3d:59:fc:bc:4b:1a:55:fb:36:75:ff:e3:88:
73:e3:16:4d:2b:17:7b:2a:21:a3:18:14:04:19:b3:b8:11:39:
55:3f:ce:21:b7:d3:5d:8d:78:d5:3a:e0:b2:17:41:ad:3c:8e:
a5:a2:ba:eb:3d:b6:9e:2c:ef:7d:d5:cc:71:cb:07:54:21:42:
81:79:45:2b:93:74:93:a1:c9:f1:5e:5e:11:3d:ac:df:55:98:
37:44:d2:55:a5:15:a9:33:79:6e:fe:49:6d:e5:7b:a0:1c:12:
c5:1b:4d:33
ECDSA (P-256) - self-signed:
step certificate create "Smallstep self-signed" cert.ecdsa.pem key.ecdsa.pem \
--no-password --insecure \
--profile self-signed --subtle \
--not-before "2021-01-01T00:00:00+00:00" \
--not-after "2031-01-01T00:00:00+00:00" \
--san "example.test" \
--san "mail.example.test" \
--kty EC --crv P-256
Certificate Details:
Certificate:
Data:
Version: 3 (0x2)
Serial Number: 311463463867833685003701497925006766941 (0xea51ae60cd02784bbf1ba4e367ffb35d)
Signature Algorithm: ECDSA-SHA256
Issuer: CN=Smallstep self-signed
Validity
Not Before: Jan 1 00:00:00 2021 UTC
Not After : Jan 1 00:00:00 2031 UTC
Subject: CN=Smallstep self-signed
Subject Public Key Info:
Public Key Algorithm: ECDSA
Public-Key: (256 bit)
X:
b1:f7:b1:12:75:17:a8:72:9a:39:31:ef:f0:61:b2:
f4:0c:88:c6:05:b2:12:f2:99:e0:ac:81:78:4c:72:
94:e9
Y:
52:8f:e9:c1:7b:b0:15:83:90:06:30:d2:c0:6b:66:
63:31:14:54:28:80:1d:89:6e:a4:2c:dd:59:17:5f:
a6:3e
Curve: P-256
X509v3 extensions:
X509v3 Key Usage: critical
Digital Signature
X509v3 Extended Key Usage:
Server Authentication, Client Authentication
X509v3 Subject Key Identifier:
14:9F:BA:EB:14:52:9F:2C:13:B2:E9:F1:77:DA:5B:F6:E2:1D:54:BD
X509v3 Subject Alternative Name:
DNS:example.test, DNS:mail.example.test
Signature Algorithm: ECDSA-SHA256
30:46:02:21:00:f8:72:3d:90:7e:db:9e:7a:4f:6d:80:fb:fa:
dc:42:43:e2:dc:8f:6a:ec:18:c5:af:e1:ea:03:fd:66:78:a2:
01:02:21:00:f7:86:58:81:17:f5:74:5b:14:c8:0f:93:e2:bb:
b8:e9:90:47:c0:f7:b1:60:82:d9:b4:1a:fc:fa:66:fa:48:5c
self-signed certs lacks a chain of trust for verifying a certificate. See test/mail_ssl_manual.bats which covers verification test.
The minimal setup to satisfy verification is adding a Root CA (self-signed) that is used to sign the server certificate (leaf cert):
Create an ECDSA Root CA cert:
step certificate create "Smallstep Root CA" ca-cert.ecdsa.pem ca-key.ecdsa.pem \
--no-password --insecure \
--profile root-ca \
--not-before "2021-01-01T00:00:00+00:00" \
--not-after "2031-01-01T00:00:00+00:00" \
--san "example.test" \
--san "mail.example.test" \
--kty EC --crv P-256
Create an ECDSA Leaf cert, signed with the Root CA key we just created:
step certificate create "Smallstep Leaf" cert.ecdsa.pem key.ecdsa.pem \
--no-password --insecure \
--profile leaf \
--ca ca-cert.ecdsa.pem \
--ca-key ca-key.ecdsa.pem \
--not-before "2021-01-01T00:00:00+00:00" \
--not-after "2031-01-01T00:00:00+00:00" \
--san "example.test" \
--san "mail.example.test" \
--kty EC --crv P-256
The Root CA certificate does not need to have the same key type as the Leaf certificate, you can mix and match if necessary (eg: an ECDSA and an RSA leaf certs with shared ECDSA Root CA cert).
Certificate Details (signed by Root CA key):
step certificate inspect with_ca/ecdsa/cert.ecdsa.pem:
Certificate:
Data:
Version: 3 (0x2)
Serial Number: 28540880372304824564361820670143583738 (0x1578c60b9eedca127fe041712f9d55fa)
Signature Algorithm: ECDSA-SHA256
Issuer: CN=Smallstep Root CA
Validity
Not Before: Jan 1 00:00:00 2021 UTC
Not After : Jan 1 00:00:00 2031 UTC
Subject: CN=Smallstep Leaf
Subject Public Key Info:
Public Key Algorithm: ECDSA
Public-Key: (256 bit)
X:
b6:64:18:5f:f6:3f:b6:b1:da:09:00:27:e9:70:4e:
8e:11:c4:58:8d:02:a2:46:f6:5b:d5:12:9b:ea:6a:
e4:39
Y:
87:56:d8:43:6b:4d:5d:4a:44:73:d2:81:34:1d:cd:
de:53:ed:62:c4:61:76:c6:bf:96:0a:0a:8e:10:fa:
c2:63
Curve: P-256
X509v3 extensions:
X509v3 Key Usage: critical
Digital Signature
X509v3 Extended Key Usage:
Server Authentication, Client Authentication
X509v3 Subject Key Identifier:
48:C4:A2:B2:31:9B:9C:3D:4D:BD:58:45:60:F0:C6:16:EB:74:C0:3B
X509v3 Authority Key Identifier:
keyid:3F:3D:65:1A:72:82:16:C6:20:E8:B6:FC:1B:2E:6D:A4:9C:2C:92:78
X509v3 Subject Alternative Name:
DNS:example.test, DNS:mail.example.test
Signature Algorithm: ECDSA-SHA256
30:46:02:21:00:b6:dc:7d:ba:f6:d9:b1:3f:28:4d:6d:4c:a4:
e9:c5:24:80:d4:6c:a5:fc:9f:74:4e:9a:bb:5b:ca:8a:5e:dd:
32:02:21:00:e2:c8:8b:1b:be:a2:f9:5f:cd:41:8c:0a:75:71:
ca:e9:be:65:d1:ca:5e:50:77:f7:8a:c0:f8:03:77:1b:53:0a
Root CA Certificate Details (self-signed):
step certificate inspect with_ca/ecdsa/ca-cert.ecdsa.pem:
Certificate:
Data:
Version: 3 (0x2)
Serial Number: 83158808788179848488617675347018882219 (0x3e8fcdd2d80ab546924c05b4d9339cab)
Signature Algorithm: ECDSA-SHA256
Issuer: CN=Smallstep Root CA
Validity
Not Before: Jan 1 00:00:00 2021 UTC
Not After : Jan 1 00:00:00 2031 UTC
Subject: CN=Smallstep Root CA
Subject Public Key Info:
Public Key Algorithm: ECDSA
Public-Key: (256 bit)
X:
76:30:c0:21:d2:6c:6b:ca:de:be:1d:c3:5c:67:08:
93:bf:73:53:2a:23:5d:d8:06:2a:8b:09:bc:39:fd:
0b:0d
Y:
a7:74:1f:7c:b9:95:73:6c:ba:00:00:d7:52:06:0c:
e9:00:c8:aa:bb:e1:50:e7:ec:ff:bf:e5:30:bb:9b:
18:07
Curve: P-256
X509v3 extensions:
X509v3 Key Usage: critical
Certificate Sign, CRL Sign
X509v3 Basic Constraints: critical
CA:TRUE, pathlen:1
X509v3 Subject Key Identifier:
3F:3D:65:1A:72:82:16:C6:20:E8:B6:FC:1B:2E:6D:A4:9C:2C:92:78
Signature Algorithm: ECDSA-SHA256
30:45:02:21:00:bf:d7:51:c7:7b:67:41:90:ac:c5:89:cd:04:
60:7d:6b:da:8d:75:c2:c6:1c:18:93:82:79:96:35:19:a4:ea:
2f:02:20:5a:bc:95:3b:de:f6:8b:00:fd:1a:69:81:57:b5:b6:
91:0f:10:ef:2b:b2:39:83:c0:3c:a0:26:21:51:4b:40:3c
When bundling chain of trust into a single certificate file (eg: fullchain.pem), starting with the server cert, include any additional parent certificates in the chain - but do not add the final Root CA cert; otherwise you'll get a related error with not being able to verify trust:
$ openssl s_client -connect mail.example.test:587 -starttls smtp
# Verification error: self signed certificate in certificate chain
Thus, the minimal bundle would be leaf->intermediate (fullchain.pem) with separate Root CA cert.