8c8423aa3d
Signed-off-by: Brian DeHamer <bdehamer@github.com> Co-authored-by: Zach Steindler <steiza@github.com> Co-authored-by: Phill MV <phillmv@github.com>
127 lines
3.5 KiB
Go
127 lines
3.5 KiB
Go
package verify
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import (
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"errors"
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"fmt"
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"regexp"
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"github.com/sigstore/sigstore-go/pkg/fulcio/certificate"
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"github.com/sigstore/sigstore-go/pkg/verify"
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"github.com/cli/cli/v2/pkg/cmd/attestation/artifact"
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"github.com/cli/cli/v2/pkg/cmd/attestation/verification"
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)
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const (
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// represents the GitHub hosted runner in the certificate RunnerEnvironment extension
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GitHubRunner = "github-hosted"
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hostRegex = `^[a-zA-Z0-9-]+\.[a-zA-Z0-9-]+.*$`
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)
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func expandToGitHubURL(tenant, ownerOrRepo string) string {
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if tenant == "" {
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return fmt.Sprintf("(?i)^https://github.com/%s/", ownerOrRepo)
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}
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return fmt.Sprintf("(?i)^https://%s.ghe.com/%s/", tenant, ownerOrRepo)
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}
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func buildSANMatcher(opts *Options) (verify.SubjectAlternativeNameMatcher, error) {
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if opts.SignerRepo != "" {
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signedRepoRegex := expandToGitHubURL(opts.Tenant, opts.SignerRepo)
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return verify.NewSANMatcher("", signedRepoRegex)
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} else if opts.SignerWorkflow != "" {
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validatedWorkflowRegex, err := validateSignerWorkflow(opts)
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if err != nil {
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return verify.SubjectAlternativeNameMatcher{}, err
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}
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return verify.NewSANMatcher("", validatedWorkflowRegex)
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} else if opts.SAN != "" || opts.SANRegex != "" {
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return verify.NewSANMatcher(opts.SAN, opts.SANRegex)
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}
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return verify.SubjectAlternativeNameMatcher{}, nil
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}
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func buildCertificateIdentityOption(opts *Options, runnerEnv string) (verify.PolicyOption, error) {
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sanMatcher, err := buildSANMatcher(opts)
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if err != nil {
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return nil, err
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}
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// Accept any issuer, we will verify the issuer as part of the extension verification
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issuerMatcher, err := verify.NewIssuerMatcher("", ".*")
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if err != nil {
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return nil, err
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}
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extensions := certificate.Extensions{
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RunnerEnvironment: runnerEnv,
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}
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certId, err := verify.NewCertificateIdentity(sanMatcher, issuerMatcher, extensions)
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if err != nil {
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return nil, err
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}
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return verify.WithCertificateIdentity(certId), nil
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}
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func buildVerifyCertIdOption(opts *Options) (verify.PolicyOption, error) {
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if opts.DenySelfHostedRunner {
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withGHRunner, err := buildCertificateIdentityOption(opts, GitHubRunner)
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if err != nil {
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return nil, err
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}
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return withGHRunner, nil
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}
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// if Extensions.RunnerEnvironment value is set to the empty string
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// through the second function argument,
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// no certificate matching will happen on the RunnerEnvironment field
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withAnyRunner, err := buildCertificateIdentityOption(opts, "")
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if err != nil {
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return nil, err
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}
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return withAnyRunner, nil
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}
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func buildVerifyPolicy(opts *Options, a artifact.DigestedArtifact) (verify.PolicyBuilder, error) {
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artifactDigestPolicyOption, err := verification.BuildDigestPolicyOption(a)
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if err != nil {
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return verify.PolicyBuilder{}, err
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}
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certIdOption, err := buildVerifyCertIdOption(opts)
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if err != nil {
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return verify.PolicyBuilder{}, err
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}
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policy := verify.NewPolicy(artifactDigestPolicyOption, certIdOption)
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return policy, nil
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}
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func addSchemeToRegex(s string) string {
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return fmt.Sprintf("^https://%s", s)
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}
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func validateSignerWorkflow(opts *Options) (string, error) {
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// we expect a provided workflow argument be in the format [HOST/]/<OWNER>/<REPO>/path/to/workflow.yml
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// if the provided workflow does not contain a host, set the host
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match, err := regexp.MatchString(hostRegex, opts.SignerWorkflow)
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if err != nil {
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return "", err
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}
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if match {
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return addSchemeToRegex(opts.SignerWorkflow), nil
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}
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if opts.Hostname == "" {
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return "", errors.New("unknown host")
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}
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return addSchemeToRegex(fmt.Sprintf("%s/%s", opts.Hostname, opts.SignerWorkflow)), nil
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}
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