90 lines
3.3 KiB
Markdown
90 lines
3.3 KiB
Markdown
---
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stage: Systems
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group: Distribution
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info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/product/ux/technical-writing/#assignments
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---
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# Signing outgoing email with S/MIME **(FREE SELF)**
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Notification emails sent by GitLab can be signed with S/MIME for improved
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security.
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Be aware that S/MIME certificates and TLS/SSL certificates are not the
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same and are used for different purposes: TLS creates a secure channel, whereas
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S/MIME signs and/or encrypts the message itself
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## Enable S/MIME signing
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This setting must be explicitly enabled and a single pair of key and certificate
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files must be provided:
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- Both files must be PEM-encoded.
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- The key file must be unencrypted so that GitLab can read it without user
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intervention.
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- Only RSA keys are supported.
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Optionally, you can also provide a bundle of CA certs (PEM-encoded) to be
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included on each signature. This is typically an intermediate CA.
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WARNING:
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Be mindful of the access levels for your private keys and visibility to
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third parties.
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**For Omnibus installations:**
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1. Edit `/etc/gitlab/gitlab.rb` and adapt the file paths:
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```ruby
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gitlab_rails['gitlab_email_smime_enabled'] = true
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gitlab_rails['gitlab_email_smime_key_file'] = '/etc/gitlab/ssl/gitlab_smime.key'
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gitlab_rails['gitlab_email_smime_cert_file'] = '/etc/gitlab/ssl/gitlab_smime.crt'
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# Optional
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gitlab_rails['gitlab_email_smime_ca_certs_file'] = '/etc/gitlab/ssl/gitlab_smime_cas.crt'
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```
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1. Save the file and [reconfigure GitLab](restart_gitlab.md#omnibus-gitlab-reconfigure) for the changes to take effect.
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The key must be readable by the GitLab system user (`git` by default).
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**For installations from source:**
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1. Edit `config/gitlab.yml`:
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```yaml
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email_smime:
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# Uncomment and set to true if you need to enable email S/MIME signing (default: false)
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enabled: true
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# S/MIME private key file in PEM format, unencrypted
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# Default is '.gitlab_smime_key' relative to Rails.root (i.e. root of the GitLab app).
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key_file: /etc/pki/smime/private/gitlab.key
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# S/MIME public certificate key in PEM format, will be attached to signed messages
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# Default is '.gitlab_smime_cert' relative to Rails.root (i.e. root of the GitLab app).
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cert_file: /etc/pki/smime/certs/gitlab.crt
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# S/MIME extra CA public certificates in PEM format, will be attached to signed messages
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# Optional
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ca_certs_file: /etc/pki/smime/certs/gitlab_cas.crt
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```
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1. Save the file and [restart GitLab](restart_gitlab.md#installations-from-source) for the changes to take effect.
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The key must be readable by the GitLab system user (`git` by default).
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### How to convert S/MIME PKCS #12 format to PEM encoding
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Typically S/MIME certificates are handled in binary Public Key Cryptography Standards (PKCS) #12 format
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(`.pfx` or `.p12` extensions), which contain the following in a single encrypted file:
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- Public certificate
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- Intermediate certificates (if any)
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- Private key
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To export the required files in PEM encoding from the PKCS #12 file, the
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`openssl` command can be used:
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```shell
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#-- Extract private key in PEM encoding (no password, unencrypted)
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$ openssl pkcs12 -in gitlab.p12 -nocerts -nodes -out gitlab.key
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#-- Extract certificates in PEM encoding (full certs chain including CA)
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$ openssl pkcs12 -in gitlab.p12 -nokeys -out gitlab.crt
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```
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