diff --git a/authority/authority.go b/authority/authority.go index 295c6413..7d527b13 100644 --- a/authority/authority.go +++ b/authority/authority.go @@ -1,6 +1,7 @@ package authority import ( + "bytes" "context" "crypto" "crypto/sha256" @@ -24,6 +25,7 @@ import ( adminDBNosql "github.com/smallstep/certificates/authority/admin/db/nosql" "github.com/smallstep/certificates/authority/administrator" "github.com/smallstep/certificates/authority/config" + "github.com/smallstep/certificates/authority/internal/constraints" "github.com/smallstep/certificates/authority/policy" "github.com/smallstep/certificates/authority/provisioner" "github.com/smallstep/certificates/cas" @@ -46,14 +48,15 @@ type Authority struct { linkedCAToken string // X509 CA - password []byte - issuerPassword []byte - x509CAService cas.CertificateAuthorityService - rootX509Certs []*x509.Certificate - rootX509CertPool *x509.CertPool - federatedX509Certs []*x509.Certificate - certificates *sync.Map - x509Enforcers []provisioner.CertificateEnforcer + password []byte + issuerPassword []byte + x509CAService cas.CertificateAuthorityService + rootX509Certs []*x509.Certificate + rootX509CertPool *x509.CertPool + federatedX509Certs []*x509.Certificate + intermediateX509Certs []*x509.Certificate + certificates *sync.Map + x509Enforcers []provisioner.CertificateEnforcer // SCEP CA scepService *scep.Service @@ -80,8 +83,9 @@ type Authority struct { authorizeRenewFunc provisioner.AuthorizeRenewFunc authorizeSSHRenewFunc provisioner.AuthorizeSSHRenewFunc - // Policy engines - policyEngine *policy.Engine + // Constraints and Policy engines + constraintsEngine *constraints.Engine + policyEngine *policy.Engine adminMutex sync.RWMutex @@ -373,6 +377,12 @@ func (a *Authority) init() error { if err != nil { return err } + // If not defined with an option, add intermediates to the list of + // certificates used for name constraints validation at issuance + // time. + if len(a.intermediateX509Certs) == 0 { + a.intermediateX509Certs = append(a.intermediateX509Certs, options.CertificateChain...) + } } a.x509CAService, err = cas.New(ctx, options) if err != nil { @@ -610,6 +620,21 @@ func (a *Authority) init() error { return err } + // Load X509 constraints engine. + // + // This is currently only available in CA mode. + if size := len(a.intermediateX509Certs); size > 0 { + last := a.intermediateX509Certs[size-1] + constraintCerts := make([]*x509.Certificate, 0, size+1) + constraintCerts = append(constraintCerts, a.intermediateX509Certs...) + for _, root := range a.rootX509Certs { + if bytes.Equal(last.RawIssuer, root.RawSubject) && bytes.Equal(last.AuthorityKeyId, root.SubjectKeyId) { + constraintCerts = append(constraintCerts, root) + } + } + a.constraintsEngine = constraints.New(constraintCerts...) + } + // Load x509 and SSH Policy Engines if err := a.reloadPolicyEngines(ctx); err != nil { return err diff --git a/authority/internal/constraints/constraints.go b/authority/internal/constraints/constraints.go new file mode 100644 index 00000000..a1cbde7e --- /dev/null +++ b/authority/internal/constraints/constraints.go @@ -0,0 +1,135 @@ +package constraints + +import ( + "crypto/x509" + "fmt" + "net" + "net/http" + "net/url" + + "github.com/smallstep/certificates/errs" +) + +// ConstraintError is the typed error that will be returned if a constraint +// error is found. +type ConstraintError struct { + Type string + Name string + Detail string +} + +// Error implements the error interface. +func (e ConstraintError) Error() string { + return e.Detail +} + +// As implements the As(any) bool interface and allows to use "errors.As()" to +// convert the ConstraintError to an errs.Error. +func (e ConstraintError) As(v any) bool { + if err, ok := v.(**errs.Error); ok { + *err = &errs.Error{ + Status: http.StatusForbidden, + Msg: e.Detail, + Err: e, + } + return true + } + return false +} + +// Engine implements a constraint validator for DNS names, IP addresses, Email +// addresses and URIs. +type Engine struct { + hasNameConstraints bool + permittedDNSDomains []string + excludedDNSDomains []string + permittedIPRanges []*net.IPNet + excludedIPRanges []*net.IPNet + permittedEmailAddresses []string + excludedEmailAddresses []string + permittedURIDomains []string + excludedURIDomains []string +} + +// New creates a constraint validation engine that contains the given chain of +// certificates. +func New(chain ...*x509.Certificate) *Engine { + e := new(Engine) + for _, crt := range chain { + e.permittedDNSDomains = append(e.permittedDNSDomains, crt.PermittedDNSDomains...) + e.excludedDNSDomains = append(e.excludedDNSDomains, crt.ExcludedDNSDomains...) + e.permittedIPRanges = append(e.permittedIPRanges, crt.PermittedIPRanges...) + e.excludedIPRanges = append(e.excludedIPRanges, crt.ExcludedIPRanges...) + e.permittedEmailAddresses = append(e.permittedEmailAddresses, crt.PermittedEmailAddresses...) + e.excludedEmailAddresses = append(e.excludedEmailAddresses, crt.ExcludedEmailAddresses...) + e.permittedURIDomains = append(e.permittedURIDomains, crt.PermittedURIDomains...) + e.excludedURIDomains = append(e.excludedURIDomains, crt.ExcludedURIDomains...) + } + + e.hasNameConstraints = len(e.permittedDNSDomains) > 0 || len(e.excludedDNSDomains) > 0 || + len(e.permittedIPRanges) > 0 || len(e.excludedIPRanges) > 0 || + len(e.permittedEmailAddresses) > 0 || len(e.excludedEmailAddresses) > 0 || + len(e.permittedURIDomains) > 0 || len(e.excludedURIDomains) > 0 + + return e +} + +// Validate checks the given names with the name constraints defined in the +// service. +func (e *Engine) Validate(dnsNames []string, ipAddresses []net.IP, emailAddresses []string, uris []*url.URL) error { + if e == nil || !e.hasNameConstraints { + return nil + } + + for _, name := range dnsNames { + if err := checkNameConstraints("DNS name", name, name, e.permittedDNSDomains, e.excludedDNSDomains, + func(parsedName, constraint any) (bool, error) { + return matchDomainConstraint(parsedName.(string), constraint.(string)) + }, + ); err != nil { + return err + } + } + + for _, ip := range ipAddresses { + if err := checkNameConstraints("IP address", ip.String(), ip, e.permittedIPRanges, e.excludedIPRanges, + func(parsedName, constraint any) (bool, error) { + return matchIPConstraint(parsedName.(net.IP), constraint.(*net.IPNet)) + }, + ); err != nil { + return err + } + } + + for _, email := range emailAddresses { + mailbox, ok := parseRFC2821Mailbox(email) + if !ok { + return fmt.Errorf("cannot parse rfc822Name %q", email) + } + if err := checkNameConstraints("Email address", email, mailbox, e.permittedEmailAddresses, e.excludedEmailAddresses, + func(parsedName, constraint any) (bool, error) { + return matchEmailConstraint(parsedName.(rfc2821Mailbox), constraint.(string)) + }, + ); err != nil { + return err + } + } + + for _, uri := range uris { + if err := checkNameConstraints("URI", uri.String(), uri, e.permittedURIDomains, e.excludedURIDomains, + func(parsedName, constraint any) (bool, error) { + return matchURIConstraint(parsedName.(*url.URL), constraint.(string)) + }, + ); err != nil { + return err + } + } + + return nil +} + +// ValidateCertificate validates the DNS names, IP addresses, Email addresses +// and URIs present in the given certificate. +func (e *Engine) ValidateCertificate(cert *x509.Certificate) error { + return e.Validate(cert.DNSNames, cert.IPAddresses, cert.EmailAddresses, cert.URIs) +} diff --git a/authority/internal/constraints/constraints_test.go b/authority/internal/constraints/constraints_test.go new file mode 100644 index 00000000..0f6d0ef1 --- /dev/null +++ b/authority/internal/constraints/constraints_test.go @@ -0,0 +1,334 @@ +package constraints + +import ( + "crypto/x509" + "net" + "net/url" + "reflect" + "testing" + + "go.step.sm/crypto/minica" +) + +func TestNew(t *testing.T) { + ca1, err := minica.New() + if err != nil { + t.Fatal(err) + } + + ca2, err := minica.New( + minica.WithIntermediateTemplate(`{ + "subject": {{ toJson .Subject }}, + "keyUsage": ["certSign", "crlSign"], + "basicConstraints": { + "isCA": true, + "maxPathLen": 0 + }, + "nameConstraints": { + "critical": true, + "permittedDNSDomains": ["internal.example.org"], + "excludedDNSDomains": ["internal.example.com"], + "permittedIPRanges": ["192.168.1.0/24", "192.168.2.1/32"], + "excludedIPRanges": ["192.168.3.0/24", "192.168.4.0/28"], + "permittedEmailAddresses": ["root@example.org", "example.org", ".acme.org"], + "excludedEmailAddresses": ["root@example.com", "example.com", ".acme.com"], + "permittedURIDomains": ["host.example.org", ".acme.org"], + "excludedURIDomains": ["host.example.com", ".acme.com"] + } + }`), + ) + if err != nil { + t.Fatal(err) + } + + type args struct { + chain []*x509.Certificate + } + tests := []struct { + name string + args args + want *Engine + }{ + {"ok", args{[]*x509.Certificate{ca1.Intermediate, ca1.Root}}, &Engine{ + hasNameConstraints: false, + }}, + {"ok with constraints", args{[]*x509.Certificate{ca2.Intermediate, ca2.Root}}, &Engine{ + hasNameConstraints: true, + permittedDNSDomains: []string{"internal.example.org"}, + excludedDNSDomains: []string{"internal.example.com"}, + permittedIPRanges: []*net.IPNet{ + {IP: net.ParseIP("192.168.1.0").To4(), Mask: net.IPMask{255, 255, 255, 0}}, + {IP: net.ParseIP("192.168.2.1").To4(), Mask: net.IPMask{255, 255, 255, 255}}, + }, + excludedIPRanges: []*net.IPNet{ + {IP: net.ParseIP("192.168.3.0").To4(), Mask: net.IPMask{255, 255, 255, 0}}, + {IP: net.ParseIP("192.168.4.0").To4(), Mask: net.IPMask{255, 255, 255, 240}}, + }, + permittedEmailAddresses: []string{"root@example.org", "example.org", ".acme.org"}, + excludedEmailAddresses: []string{"root@example.com", "example.com", ".acme.com"}, + permittedURIDomains: []string{"host.example.org", ".acme.org"}, + excludedURIDomains: []string{"host.example.com", ".acme.com"}, + }}, + } + for _, tt := range tests { + t.Run(tt.name, func(t *testing.T) { + if got := New(tt.args.chain...); !reflect.DeepEqual(got, tt.want) { + t.Errorf("New() = %v, want %v", got, tt.want) + } + }) + } +} + +func TestNew_hasNameConstraints(t *testing.T) { + tests := []struct { + name string + fn func(c *x509.Certificate) + want bool + }{ + {"no constraints", func(c *x509.Certificate) {}, false}, + {"permittedDNSDomains", func(c *x509.Certificate) { c.PermittedDNSDomains = []string{"constraint"} }, true}, + {"excludedDNSDomains", func(c *x509.Certificate) { c.ExcludedDNSDomains = []string{"constraint"} }, true}, + {"permittedIPRanges", func(c *x509.Certificate) { + c.PermittedIPRanges = []*net.IPNet{{IP: net.ParseIP("192.168.3.0").To4(), Mask: net.IPMask{255, 255, 255, 0}}} + }, true}, + {"excludedIPRanges", func(c *x509.Certificate) { + c.ExcludedIPRanges = []*net.IPNet{{IP: net.ParseIP("192.168.3.0").To4(), Mask: net.IPMask{255, 255, 255, 0}}} + }, true}, + {"permittedEmailAddresses", func(c *x509.Certificate) { c.PermittedEmailAddresses = []string{"constraint"} }, true}, + {"excludedEmailAddresses", func(c *x509.Certificate) { c.ExcludedEmailAddresses = []string{"constraint"} }, true}, + {"permittedURIDomains", func(c *x509.Certificate) { c.PermittedURIDomains = []string{"constraint"} }, true}, + {"excludedURIDomains", func(c *x509.Certificate) { c.ExcludedURIDomains = []string{"constraint"} }, true}, + } + for _, tt := range tests { + t.Run(tt.name, func(t *testing.T) { + cert := &x509.Certificate{} + tt.fn(cert) + if e := New(cert); e.hasNameConstraints != tt.want { + t.Errorf("Engine.hasNameConstraints = %v, want %v", e.hasNameConstraints, tt.want) + } + }) + } +} + +func TestEngine_Validate(t *testing.T) { + type fields struct { + hasNameConstraints bool + permittedDNSDomains []string + excludedDNSDomains []string + permittedIPRanges []*net.IPNet + excludedIPRanges []*net.IPNet + permittedEmailAddresses []string + excludedEmailAddresses []string + permittedURIDomains []string + excludedURIDomains []string + } + type args struct { + dnsNames []string + ipAddresses []net.IP + emailAddresses []string + uris []*url.URL + } + tests := []struct { + name string + fields fields + args args + wantErr bool + }{ + {"ok", fields{hasNameConstraints: false}, args{ + dnsNames: []string{"example.com", "host.example.com"}, + ipAddresses: []net.IP{{192, 168, 1, 1}, {0x26, 0x00, 0x1f, 0x1c, 0x47, 0x01, 0x9d, 0x00, 0xc3, 0xa7, 0x66, 0x94, 0x87, 0x0f, 0x20, 0x72}}, + emailAddresses: []string{"root@example.com"}, + uris: []*url.URL{{Scheme: "https", Host: "example.com", Path: "/uuid/c6d1a755-0c12-431e-9136-b64cb3173ec7"}}, + }, false}, + {"ok permitted dns", fields{ + hasNameConstraints: true, + permittedDNSDomains: []string{"example.com"}, + }, args{dnsNames: []string{"example.com", "www.example.com"}}, false}, + {"ok not excluded dns", fields{ + hasNameConstraints: true, + excludedDNSDomains: []string{"example.org"}, + }, args{dnsNames: []string{"example.com", "www.example.com"}}, false}, + {"ok permitted ip", fields{ + hasNameConstraints: true, + permittedIPRanges: []*net.IPNet{ + {IP: net.ParseIP("192.168.1.0"), Mask: net.IPMask{255, 255, 255, 0}}, + {IP: net.ParseIP("192.168.2.1").To4(), Mask: net.IPMask{255, 255, 255, 255}}, + {IP: net.ParseIP("2600:1700:22f8:2600:e559:bd88:350a:34d6"), Mask: net.IPMask{255, 255, 255, 255, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}}, + }, + }, args{ipAddresses: []net.IP{{192, 168, 1, 10}, {192, 168, 2, 1}, {0x26, 0x0, 0x17, 0x00, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xa, 0xb, 0xc}}}, false}, + {"ok not excluded ip", fields{ + hasNameConstraints: true, + excludedIPRanges: []*net.IPNet{ + {IP: net.ParseIP("192.168.1.0"), Mask: net.IPMask{255, 255, 255, 0}}, + {IP: net.ParseIP("192.168.2.1").To4(), Mask: net.IPMask{255, 255, 255, 255}}, + }, + }, args{ipAddresses: []net.IP{{192, 168, 2, 2}, {192, 168, 3, 1}}}, false}, + {"ok permitted emails", fields{ + hasNameConstraints: true, + permittedEmailAddresses: []string{"root@example.com", "acme.org", ".acme.com"}, + }, args{emailAddresses: []string{"root@example.com", "name@acme.org", "name@coyote.acme.com", `"(quoted)"@www.acme.com`}}, false}, + {"ok not excluded emails", fields{ + hasNameConstraints: true, + excludedEmailAddresses: []string{"root@example.com", "acme.org", ".acme.com"}, + }, args{emailAddresses: []string{"name@example.com", "root@acme.com", "root@other.com"}}, false}, + {"ok permitted uris", fields{ + hasNameConstraints: true, + permittedURIDomains: []string{"example.com", ".acme.com"}, + }, args{uris: []*url.URL{{Scheme: "https", Host: "example.com", Path: "/path"}, {Scheme: "https", Host: "www.acme.com", Path: "/path"}}}, false}, + {"ok not excluded uris", fields{ + hasNameConstraints: true, + excludedURIDomains: []string{"example.com", ".acme.com"}, + }, args{uris: []*url.URL{{Scheme: "https", Host: "example.org", Path: "/path"}, {Scheme: "https", Host: "acme.com", Path: "/path"}}}, false}, + {"fail permitted dns", fields{ + hasNameConstraints: true, + permittedDNSDomains: []string{"example.com"}, + }, args{dnsNames: []string{"www.example.com", "www.example.org"}}, true}, + {"fail not excluded dns", fields{ + hasNameConstraints: true, + excludedDNSDomains: []string{"example.org"}, + }, args{dnsNames: []string{"example.com", "www.example.org"}}, true}, + {"fail permitted ip", fields{ + hasNameConstraints: true, + permittedIPRanges: []*net.IPNet{ + {IP: net.ParseIP("192.168.1.0").To4(), Mask: net.IPMask{255, 255, 255, 0}}, + {IP: net.ParseIP("192.168.2.1").To4(), Mask: net.IPMask{255, 255, 255, 255}}, + }, + }, args{ipAddresses: []net.IP{{192, 168, 1, 10}, {192, 168, 2, 10}}}, true}, + {"fail not excluded ip", fields{ + hasNameConstraints: true, + excludedIPRanges: []*net.IPNet{ + {IP: net.ParseIP("192.168.1.0").To4(), Mask: net.IPMask{255, 255, 255, 0}}, + {IP: net.ParseIP("192.168.2.1").To4(), Mask: net.IPMask{255, 255, 255, 255}}, + }, + }, args{ipAddresses: []net.IP{{192, 168, 2, 2}, {192, 168, 1, 1}}}, true}, + {"fail permitted emails", fields{ + hasNameConstraints: true, + permittedEmailAddresses: []string{"root@example.com", "acme.org", ".acme.com"}, + }, args{emailAddresses: []string{"root@example.com", "name@acme.org", "name@acme.com"}}, true}, + {"fail not excluded emails", fields{ + hasNameConstraints: true, + excludedEmailAddresses: []string{"root@example.com", "acme.org", ".acme.com"}, + }, args{emailAddresses: []string{"name@example.com", "root@example.com"}}, true}, + {"fail permitted uris", fields{ + hasNameConstraints: true, + permittedURIDomains: []string{"example.com", ".acme.com"}, + }, args{uris: []*url.URL{{Scheme: "https", Host: "example.com", Path: "/path"}, {Scheme: "https", Host: "acme.com", Path: "/path"}}}, true}, + {"fail not excluded uris", fields{ + hasNameConstraints: true, + excludedURIDomains: []string{"example.com", ".acme.com"}, + }, args{uris: []*url.URL{{Scheme: "https", Host: "www.example.com", Path: "/path"}, {Scheme: "https", Host: "acme.com", Path: "/path"}}}, true}, + {"fail parse emails", fields{ + hasNameConstraints: true, + permittedEmailAddresses: []string{"example.com"}, + }, args{emailAddresses: []string{`(notquoted)@example.com`}}, true}, + {"fail match dns", fields{ + hasNameConstraints: true, + permittedDNSDomains: []string{"example.com"}, + }, args{dnsNames: []string{`www.example.com.`}}, true}, + {"fail match email", fields{ + hasNameConstraints: true, + excludedEmailAddresses: []string{`(notquoted)@example.com`}, + }, args{emailAddresses: []string{`ok@example.com`}}, true}, + {"fail match uri", fields{ + hasNameConstraints: true, + permittedURIDomains: []string{"example.com"}, + }, args{uris: []*url.URL{{Scheme: "urn", Opaque: "uuid:36efb1ae-6617-4b23-b799-874a37aaea1c"}}}, true}, + } + for _, tt := range tests { + t.Run(tt.name, func(t *testing.T) { + e := &Engine{ + hasNameConstraints: tt.fields.hasNameConstraints, + permittedDNSDomains: tt.fields.permittedDNSDomains, + excludedDNSDomains: tt.fields.excludedDNSDomains, + permittedIPRanges: tt.fields.permittedIPRanges, + excludedIPRanges: tt.fields.excludedIPRanges, + permittedEmailAddresses: tt.fields.permittedEmailAddresses, + excludedEmailAddresses: tt.fields.excludedEmailAddresses, + permittedURIDomains: tt.fields.permittedURIDomains, + excludedURIDomains: tt.fields.excludedURIDomains, + } + if err := e.Validate(tt.args.dnsNames, tt.args.ipAddresses, tt.args.emailAddresses, tt.args.uris); (err != nil) != tt.wantErr { + t.Errorf("service.Validate() error = %v, wantErr %v", err, tt.wantErr) + } + }) + } +} + +func TestEngine_Validate_nil(t *testing.T) { + var e *Engine + if err := e.Validate([]string{"www.example.com"}, nil, nil, nil); err != nil { + t.Errorf("service.Validate() error = %v, wantErr false", err) + } +} + +func TestEngine_ValidateCertificate(t *testing.T) { + type fields struct { + hasNameConstraints bool + permittedDNSDomains []string + excludedDNSDomains []string + permittedIPRanges []*net.IPNet + excludedIPRanges []*net.IPNet + permittedEmailAddresses []string + excludedEmailAddresses []string + permittedURIDomains []string + excludedURIDomains []string + } + type args struct { + cert *x509.Certificate + } + tests := []struct { + name string + fields fields + args args + wantErr bool + }{ + {"ok", fields{hasNameConstraints: false}, args{&x509.Certificate{ + DNSNames: []string{"example.com"}, + IPAddresses: []net.IP{{127, 0, 0, 1}}, + EmailAddresses: []string{"info@example.com"}, + URIs: []*url.URL{{Scheme: "https", Host: "uuid.example.com", Path: "/dc4c76b5-5262-4551-a881-48094a604d63"}}, + }}, false}, + {"ok with constraints", fields{ + hasNameConstraints: true, + permittedDNSDomains: []string{"example.com"}, + permittedIPRanges: []*net.IPNet{ + {IP: net.ParseIP("127.0.0.1").To4(), Mask: net.IPMask{255, 255, 255, 255}}, + {IP: net.ParseIP("10.3.0.0").To4(), Mask: net.IPMask{255, 255, 0, 0}}, + }, + permittedEmailAddresses: []string{"example.com"}, + permittedURIDomains: []string{".example.com"}, + }, args{&x509.Certificate{ + DNSNames: []string{"www.example.com"}, + IPAddresses: []net.IP{{127, 0, 0, 1}, {10, 3, 1, 1}}, + EmailAddresses: []string{"info@example.com"}, + URIs: []*url.URL{{Scheme: "https", Host: "uuid.example.com", Path: "/dc4c76b5-5262-4551-a881-48094a604d63"}}, + }}, false}, + {"fail", fields{ + hasNameConstraints: true, + permittedURIDomains: []string{".example.com"}, + }, args{&x509.Certificate{ + DNSNames: []string{"example.com"}, + IPAddresses: []net.IP{{127, 0, 0, 1}}, + EmailAddresses: []string{"info@example.com"}, + URIs: []*url.URL{{Scheme: "https", Host: "uuid.example.org", Path: "/dc4c76b5-5262-4551-a881-48094a604d63"}}, + }}, true}, + } + for _, tt := range tests { + t.Run(tt.name, func(t *testing.T) { + e := &Engine{ + hasNameConstraints: tt.fields.hasNameConstraints, + permittedDNSDomains: tt.fields.permittedDNSDomains, + excludedDNSDomains: tt.fields.excludedDNSDomains, + permittedIPRanges: tt.fields.permittedIPRanges, + excludedIPRanges: tt.fields.excludedIPRanges, + permittedEmailAddresses: tt.fields.permittedEmailAddresses, + excludedEmailAddresses: tt.fields.excludedEmailAddresses, + permittedURIDomains: tt.fields.permittedURIDomains, + excludedURIDomains: tt.fields.excludedURIDomains, + } + if err := e.ValidateCertificate(tt.args.cert); (err != nil) != tt.wantErr { + t.Errorf("Engine.ValidateCertificate() error = %v, wantErr %v", err, tt.wantErr) + } + }) + } +} diff --git a/authority/internal/constraints/verify.go b/authority/internal/constraints/verify.go new file mode 100644 index 00000000..5d070f1e --- /dev/null +++ b/authority/internal/constraints/verify.go @@ -0,0 +1,383 @@ +// Copyright (c) 2009 The Go Authors. All rights reserved. +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above +// copyright notice, this list of conditions and the following disclaimer +// in the documentation and/or other materials provided with the +// distribution. +// * Neither the name of Google Inc. nor the names of its +// contributors may be used to endorse or promote products derived from +// this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +package constraints + +import ( + "bytes" + "fmt" + "net" + "net/url" + "reflect" + "strings" +) + +func checkNameConstraints(nameType, name string, parsedName, permitted, excluded any, match func(name, constraint any) (bool, error)) error { + excludedValue := reflect.ValueOf(excluded) + for i := 0; i < excludedValue.Len(); i++ { + constraint := excludedValue.Index(i).Interface() + match, err := match(parsedName, constraint) + if err != nil { + return ConstraintError{ + Type: nameType, + Name: name, + Detail: err.Error(), + } + } + + if match { + return ConstraintError{ + Type: nameType, + Name: name, + Detail: fmt.Sprintf("%s %q is excluded by constraint %q", nameType, name, constraint), + } + } + } + + var ( + err error + ok = true + ) + + permittedValue := reflect.ValueOf(permitted) + for i := 0; i < permittedValue.Len(); i++ { + constraint := permittedValue.Index(i).Interface() + if ok, err = match(parsedName, constraint); err != nil { + return ConstraintError{ + Type: nameType, + Name: name, + Detail: err.Error(), + } + } + if ok { + break + } + } + if !ok { + return ConstraintError{ + Type: nameType, + Name: name, + Detail: fmt.Sprintf("%s %q is not permitted by any constraint", nameType, name), + } + } + + return nil +} + +func matchDomainConstraint(domain, constraint string) (bool, error) { + // The meaning of zero length constraints is not specified, but this + // code follows NSS and accepts them as matching everything. + if constraint == "" { + return true, nil + } + + domainLabels, ok := domainToReverseLabels(domain) + if !ok { + return false, fmt.Errorf("internal error: cannot parse domain %q", domain) + } + + // RFC 5280 says that a leading period in a domain name means that at least + // one label must be prepended, but only for URI and email constraints, not + // DNS constraints. The code also supports that behavior for DNS + // constraints. + + mustHaveSubdomains := false + if constraint[0] == '.' { + mustHaveSubdomains = true + constraint = constraint[1:] + } + + constraintLabels, ok := domainToReverseLabels(constraint) + if !ok { + return false, fmt.Errorf("internal error: cannot parse domain %q", constraint) + } + + if len(domainLabels) < len(constraintLabels) || + (mustHaveSubdomains && len(domainLabels) == len(constraintLabels)) { + return false, nil + } + + for i, constraintLabel := range constraintLabels { + if !strings.EqualFold(constraintLabel, domainLabels[i]) { + return false, nil + } + } + + return true, nil +} + +func normalizeIP(ip net.IP) net.IP { + if ip4 := ip.To4(); ip4 != nil { + return ip4 + } + return ip +} + +func matchIPConstraint(ip net.IP, constraint *net.IPNet) (bool, error) { + ip = normalizeIP(ip) + constraintIP := normalizeIP(constraint.IP) + if len(ip) != len(constraintIP) { + return false, nil + } + + for i := range ip { + if mask := constraint.Mask[i]; ip[i]&mask != constraintIP[i]&mask { + return false, nil + } + } + + return true, nil +} + +func matchEmailConstraint(mailbox rfc2821Mailbox, constraint string) (bool, error) { + // If the constraint contains an @, then it specifies an exact mailbox + // name. + if strings.Contains(constraint, "@") { + constraintMailbox, ok := parseRFC2821Mailbox(constraint) + if !ok { + return false, fmt.Errorf("internal error: cannot parse constraint %q", constraint) + } + return mailbox.local == constraintMailbox.local && strings.EqualFold(mailbox.domain, constraintMailbox.domain), nil + } + + // Otherwise the constraint is like a DNS constraint of the domain part + // of the mailbox. + return matchDomainConstraint(mailbox.domain, constraint) +} + +func matchURIConstraint(uri *url.URL, constraint string) (bool, error) { + // From RFC 5280, Section 4.2.1.10: + // “a uniformResourceIdentifier that does not include an authority + // component with a host name specified as a fully qualified domain + // name (e.g., if the URI either does not include an authority + // component or includes an authority component in which the host name + // is specified as an IP address), then the application MUST reject the + // certificate.” + + host := uri.Host + if host == "" { + return false, fmt.Errorf("URI with empty host (%q) cannot be matched against constraints", uri.String()) + } + + if strings.Contains(host, ":") && !strings.HasSuffix(host, "]") { + var err error + host, _, err = net.SplitHostPort(uri.Host) + if err != nil { + return false, err + } + } + + if strings.HasPrefix(host, "[") && strings.HasSuffix(host, "]") || + net.ParseIP(host) != nil { + return false, fmt.Errorf("URI with IP (%q) cannot be matched against constraints", uri.String()) + } + + return matchDomainConstraint(host, constraint) +} + +// domainToReverseLabels converts a textual domain name like foo.example.com to +// the list of labels in reverse order, e.g. ["com", "example", "foo"]. +func domainToReverseLabels(domain string) (reverseLabels []string, ok bool) { + for len(domain) > 0 { + if i := strings.LastIndexByte(domain, '.'); i == -1 { + reverseLabels = append(reverseLabels, domain) + domain = "" + } else { + reverseLabels = append(reverseLabels, domain[i+1:]) + domain = domain[:i] + } + } + + if len(reverseLabels) > 0 && reverseLabels[0] == "" { + // An empty label at the end indicates an absolute value. + return nil, false + } + + for _, label := range reverseLabels { + if label == "" { + // Empty labels are otherwise invalid. + return nil, false + } + + for _, c := range label { + if c < 33 || c > 126 { + // Invalid character. + return nil, false + } + } + } + + return reverseLabels, true +} + +// rfc2821Mailbox represents a “mailbox” (which is an email address to most +// people) by breaking it into the “local” (i.e. before the '@') and “domain” +// parts. +type rfc2821Mailbox struct { + local, domain string +} + +// parseRFC2821Mailbox parses an email address into local and domain parts, +// based on the ABNF for a “Mailbox” from RFC 2821. According to RFC 5280, +// Section 4.2.1.6 that's correct for an rfc822Name from a certificate: “The +// format of an rfc822Name is a "Mailbox" as defined in RFC 2821, Section 4.1.2”. +func parseRFC2821Mailbox(in string) (mailbox rfc2821Mailbox, ok bool) { + if in == "" { + return mailbox, false + } + + localPartBytes := make([]byte, 0, len(in)/2) + + if in[0] == '"' { + // Quoted-string = DQUOTE *qcontent DQUOTE + // non-whitespace-control = %d1-8 / %d11 / %d12 / %d14-31 / %d127 + // qcontent = qtext / quoted-pair + // qtext = non-whitespace-control / + // %d33 / %d35-91 / %d93-126 + // quoted-pair = ("\" text) / obs-qp + // text = %d1-9 / %d11 / %d12 / %d14-127 / obs-text + // + // (Names beginning with “obs-” are the obsolete syntax from RFC 2822, + // Section 4. Since it has been 16 years, we no longer accept that.) + in = in[1:] + QuotedString: + for { + if in == "" { + return mailbox, false + } + c := in[0] + in = in[1:] + + switch { + case c == '"': + break QuotedString + + case c == '\\': + // quoted-pair + if in == "" { + return mailbox, false + } + if in[0] == 11 || + in[0] == 12 || + (1 <= in[0] && in[0] <= 9) || + (14 <= in[0] && in[0] <= 127) { + localPartBytes = append(localPartBytes, in[0]) + in = in[1:] + } else { + return mailbox, false + } + + case c == 11 || + c == 12 || + // Space (char 32) is not allowed based on the + // BNF, but RFC 3696 gives an example that + // assumes that it is. Several “verified” + // errata continue to argue about this point. + // We choose to accept it. + c == 32 || + c == 33 || + c == 127 || + (1 <= c && c <= 8) || + (14 <= c && c <= 31) || + (35 <= c && c <= 91) || + (93 <= c && c <= 126): + // qtext + localPartBytes = append(localPartBytes, c) + + default: + return mailbox, false + } + } + } else { + // Atom ("." Atom)* + NextChar: + for len(in) > 0 { + // atext from RFC 2822, Section 3.2.4 + c := in[0] + + switch { + case c == '\\': + // Examples given in RFC 3696 suggest that + // escaped characters can appear outside of a + // quoted string. Several “verified” errata + // continue to argue the point. We choose to + // accept it. + in = in[1:] + if in == "" { + return mailbox, false + } + fallthrough + + case ('0' <= c && c <= '9') || + ('a' <= c && c <= 'z') || + ('A' <= c && c <= 'Z') || + c == '!' || c == '#' || c == '$' || c == '%' || + c == '&' || c == '\'' || c == '*' || c == '+' || + c == '-' || c == '/' || c == '=' || c == '?' || + c == '^' || c == '_' || c == '`' || c == '{' || + c == '|' || c == '}' || c == '~' || c == '.': + localPartBytes = append(localPartBytes, in[0]) + in = in[1:] + + default: + break NextChar + } + } + + if len(localPartBytes) == 0 { + return mailbox, false + } + + // From RFC 3696, Section 3: + // “period (".") may also appear, but may not be used to start + // or end the local part, nor may two or more consecutive + // periods appear.” + twoDots := []byte{'.', '.'} + if localPartBytes[0] == '.' || + localPartBytes[len(localPartBytes)-1] == '.' || + bytes.Contains(localPartBytes, twoDots) { + return mailbox, false + } + } + + if in == "" || in[0] != '@' { + return mailbox, false + } + in = in[1:] + + // The RFC species a format for domains, but that's known to be + // violated in practice so we accept that anything after an '@' is the + // domain part. + if _, ok := domainToReverseLabels(in); !ok { + return mailbox, false + } + + mailbox.local = string(localPartBytes) + mailbox.domain = in + return mailbox, true +} diff --git a/authority/options.go b/authority/options.go index 9cef89f0..8e1a01ff 100644 --- a/authority/options.go +++ b/authority/options.go @@ -151,16 +151,23 @@ func WithKeyManager(k kms.KeyManager) Option { // WithX509Signer defines the signer used to sign X509 certificates. func WithX509Signer(crt *x509.Certificate, s crypto.Signer) Option { + return WithX509SignerChain([]*x509.Certificate{crt}, s) +} + +// WithX509SignerChain defines the signer used to sign X509 certificates. This +// option is similar to WithX509Signer but it supports a chain of intermediates. +func WithX509SignerChain(issuerChain []*x509.Certificate, s crypto.Signer) Option { return func(a *Authority) error { srv, err := cas.New(context.Background(), casapi.Options{ Type: casapi.SoftCAS, Signer: s, - CertificateChain: []*x509.Certificate{crt}, + CertificateChain: issuerChain, }) if err != nil { return err } a.x509CAService = srv + a.intermediateX509Certs = append(a.intermediateX509Certs, issuerChain...) return nil } } @@ -233,6 +240,25 @@ func WithX509FederatedCerts(certs ...*x509.Certificate) Option { } } +// WithX509IntermediateCerts is an option that allows to define the list of +// intermediate certificates that the CA will be using. This option will replace +// any intermediate certificate defined before. +// +// Note that these certificates will not be bundled with the certificates signed +// by the CA, because the CAS service will take care of that. They should match, +// but that's not guaranteed. These certificates will be mainly used for name +// constraint validation before a certificate is issued. +// +// This option should only be used on specific configurations, for example when +// WithX509SignerFunc is used, as we don't know the list of intermediates in +// advance. +func WithX509IntermediateCerts(intermediateCerts ...*x509.Certificate) Option { + return func(a *Authority) error { + a.intermediateX509Certs = intermediateCerts + return nil + } +} + // WithX509RootBundle is an option that allows to define the list of root // certificates. This option will replace any root certificate defined before. func WithX509RootBundle(pemCerts []byte) Option { diff --git a/authority/ssh.go b/authority/ssh.go index 55861ce7..1b243b39 100644 --- a/authority/ssh.go +++ b/authority/ssh.go @@ -6,7 +6,6 @@ import ( "crypto/x509" "encoding/binary" "errors" - "fmt" "net/http" "strings" "time" @@ -20,7 +19,6 @@ import ( "github.com/smallstep/certificates/authority/provisioner" "github.com/smallstep/certificates/db" "github.com/smallstep/certificates/errs" - policy "github.com/smallstep/certificates/policy" "github.com/smallstep/certificates/templates" ) @@ -255,15 +253,9 @@ func (a *Authority) SignSSH(ctx context.Context, key ssh.PublicKey, opts provisi // Check if authority is allowed to sign the certificate if err := a.isAllowedToSignSSHCertificate(certTpl); err != nil { - var pe *policy.NamePolicyError - if errors.As(err, &pe) && pe.Reason == policy.NotAllowed { - return nil, &errs.Error{ - // NOTE: custom forbidden error, so that denied name is sent to client - // as well as shown in the logs. - Status: http.StatusForbidden, - Err: fmt.Errorf("authority not allowed to sign: %w", err), - Msg: fmt.Sprintf("The request was forbidden by the certificate authority: %s", err.Error()), - } + var ee *errs.Error + if errors.As(err, &ee) { + return nil, ee } return nil, errs.InternalServerErr(err, errs.WithMessage("authority.SignSSH: error creating ssh certificate"), diff --git a/authority/tls.go b/authority/tls.go index c52e6753..efabc8f2 100644 --- a/authority/tls.go +++ b/authority/tls.go @@ -28,7 +28,6 @@ import ( casapi "github.com/smallstep/certificates/cas/apiv1" "github.com/smallstep/certificates/db" "github.com/smallstep/certificates/errs" - "github.com/smallstep/certificates/policy" ) // GetTLSOptions returns the tls options configured. @@ -213,15 +212,9 @@ func (a *Authority) Sign(csr *x509.CertificateRequest, signOpts provisioner.Sign // Check if authority is allowed to sign the certificate if err := a.isAllowedToSignX509Certificate(leaf); err != nil { - var pe *policy.NamePolicyError - if errors.As(err, &pe) && pe.Reason == policy.NotAllowed { - return nil, errs.ApplyOptions(&errs.Error{ - // NOTE: custom forbidden error, so that denied name is sent to client - // as well as shown in the logs. - Status: http.StatusForbidden, - Err: fmt.Errorf("authority not allowed to sign: %w", err), - Msg: fmt.Sprintf("The request was forbidden by the certificate authority: %s", err.Error()), - }, opts...) + var ee *errs.Error + if errors.As(err, &ee) { + return nil, errs.ApplyOptions(ee, opts...) } return nil, errs.InternalServerErr(err, errs.WithKeyVal("csr", csr), @@ -257,6 +250,9 @@ func (a *Authority) Sign(csr *x509.CertificateRequest, signOpts provisioner.Sign // isAllowedToSignX509Certificate checks if the Authority is allowed // to sign the X.509 certificate. func (a *Authority) isAllowedToSignX509Certificate(cert *x509.Certificate) error { + if err := a.constraintsEngine.ValidateCertificate(cert); err != nil { + return err + } return a.policyEngine.IsX509CertificateAllowed(cert) } @@ -352,6 +348,22 @@ func (a *Authority) Rekey(oldCert *x509.Certificate, pk crypto.PublicKey) ([]*x5 newCert.ExtraExtensions = append(newCert.ExtraExtensions, ext) } + // Check if the certificate is allowed to be renewed, name constraints might + // change over time. + // + // TODO(hslatman,maraino): consider adding policies too and consider if + // RenewSSH should check policies. + if err := a.constraintsEngine.ValidateCertificate(newCert); err != nil { + var ee *errs.Error + if errors.As(err, &ee) { + return nil, errs.ApplyOptions(ee, opts...) + } + return nil, errs.InternalServerErr(err, + errs.WithKeyVal("serialNumber", oldCert.SerialNumber.String()), + errs.WithMessage("error renewing certificate"), + ) + } + resp, err := a.x509CAService.RenewCertificate(&casapi.RenewCertificateRequest{ Template: newCert, Lifetime: lifetime, @@ -621,6 +633,18 @@ func (a *Authority) GetTLSCertificate() (*tls.Certificate, error) { certTpl.NotBefore = now.Add(-1 * time.Minute) certTpl.NotAfter = now.Add(24 * time.Hour) + // Policy and constraints require this fields to be set. At this moment they + // are only present in the extra extension. + certTpl.DNSNames = cr.DNSNames + certTpl.IPAddresses = cr.IPAddresses + certTpl.EmailAddresses = cr.EmailAddresses + certTpl.URIs = cr.URIs + + // Fail if name constraints do not allow the server names. + if err := a.constraintsEngine.ValidateCertificate(certTpl); err != nil { + return fatal(err) + } + resp, err := a.x509CAService.CreateCertificate(&casapi.CreateCertificateRequest{ Template: certTpl, CSR: cr, diff --git a/authority/tls_test.go b/authority/tls_test.go index a7971917..bc9e3e3a 100644 --- a/authority/tls_test.go +++ b/authority/tls_test.go @@ -22,6 +22,7 @@ import ( "go.step.sm/crypto/jose" "go.step.sm/crypto/keyutil" + "go.step.sm/crypto/minica" "go.step.sm/crypto/pemutil" "go.step.sm/crypto/x509util" @@ -542,7 +543,7 @@ ZYtQ9Ot36qc= notBefore: signOpts.NotBefore.Time().Truncate(time.Second), notAfter: signOpts.NotAfter.Time().Truncate(time.Second), extensionsCount: 6, - err: errors.New("authority not allowed to sign"), + err: errors.New("dns name \"test.smallstep.com\" not allowed"), code: http.StatusForbidden, } }, @@ -1589,3 +1590,86 @@ func TestAuthority_Revoke(t *testing.T) { }) } } + +func TestAuthority_constraints(t *testing.T) { + ca, err := minica.New( + minica.WithIntermediateTemplate(`{ + "subject": {{ toJson .Subject }}, + "keyUsage": ["certSign", "crlSign"], + "basicConstraints": { + "isCA": true, + "maxPathLen": 0 + }, + "nameConstraints": { + "critical": true, + "permittedDNSDomains": ["internal.example.org"], + "excludedDNSDomains": ["internal.example.com"], + "permittedIPRanges": ["192.168.1.0/24", "192.168.2.1/32"], + "excludedIPRanges": ["192.168.3.0/24", "192.168.4.0/28"], + "permittedEmailAddresses": ["root@example.org", "example.org", ".acme.org"], + "excludedEmailAddresses": ["root@example.com", "example.com", ".acme.com"], + "permittedURIDomains": ["uuid.example.org", ".acme.org"], + "excludedURIDomains": ["uuid.example.com", ".acme.com"] + } + }`), + ) + if err != nil { + t.Fatal(err) + } + + auth, err := NewEmbedded(WithX509RootCerts(ca.Root), WithX509Signer(ca.Intermediate, ca.Signer)) + if err != nil { + t.Fatal(err) + } + signer, err := keyutil.GenerateDefaultSigner() + if err != nil { + t.Fatal(err) + } + + tests := []struct { + name string + sans []string + wantErr bool + }{ + {"ok dns", []string{"internal.example.org", "host.internal.example.org"}, false}, + {"ok ip", []string{"192.168.1.10", "192.168.2.1"}, false}, + {"ok email", []string{"root@example.org", "info@example.org", "info@www.acme.org"}, false}, + {"ok uri", []string{"https://uuid.example.org/b908d973-5167-4a62-abe3-6beda358d82a", "https://uuid.acme.org/1724aae1-1bb3-44fb-83c3-9a1a18df67c8"}, false}, + {"fail permitted dns", []string{"internal.acme.org"}, true}, + {"fail excluded dns", []string{"internal.example.com"}, true}, + {"fail permitted ips", []string{"192.168.2.10"}, true}, + {"fail excluded ips", []string{"192.168.3.1"}, true}, + {"fail permitted emails", []string{"root@acme.org"}, true}, + {"fail excluded emails", []string{"root@example.com"}, true}, + {"fail permitted uris", []string{"https://acme.org/uuid/7848819c-9d0b-4e12-bbff-cd66079a3444"}, true}, + {"fail excluded uris", []string{"https://uuid.example.com/d325eda7-6356-4d60-b8f6-3d64724afeb3"}, true}, + } + for _, tt := range tests { + t.Run(tt.name, func(t *testing.T) { + csr, err := x509util.CreateCertificateRequest(tt.sans[0], tt.sans, signer) + if err != nil { + t.Fatal(err) + } + cert, err := ca.SignCSR(csr) + if err != nil { + t.Fatal(err) + } + + data := x509util.CreateTemplateData(tt.sans[0], tt.sans) + templateOption, err := provisioner.TemplateOptions(nil, data) + if err != nil { + t.Fatal(err) + } + + _, err = auth.Sign(csr, provisioner.SignOptions{}, templateOption) + if (err != nil) != tt.wantErr { + t.Errorf("Authority.Sign() error = %v, wantErr %v", err, tt.wantErr) + } + + _, err = auth.Renew(cert) + if (err != nil) != tt.wantErr { + t.Errorf("Authority.Renew() error = %v, wantErr %v", err, tt.wantErr) + } + }) + } +} diff --git a/policy/engine.go b/policy/engine.go index 4a0baa8f..c02fd7a9 100755 --- a/policy/engine.go +++ b/policy/engine.go @@ -4,11 +4,13 @@ import ( "crypto/x509" "fmt" "net" + "net/http" "net/url" + "go.step.sm/crypto/x509util" "golang.org/x/crypto/ssh" - "go.step.sm/crypto/x509util" + "github.com/smallstep/certificates/errs" ) type NamePolicyReason int @@ -62,6 +64,22 @@ func (e *NamePolicyError) Error() string { } } +// As implements the As(any) bool interface and allows to use "errors.As()" to +// convert a NotAllowed NamePolicyError to an errs.Error. +func (e *NamePolicyError) As(v any) bool { + if e.Reason == NotAllowed { + if err, ok := v.(**errs.Error); ok { + *err = &errs.Error{ + Status: http.StatusForbidden, + Msg: fmt.Sprintf("The request was forbidden by the certificate authority: %s", e.Error()), + Err: e, + } + return true + } + } + return false +} + func (e *NamePolicyError) Detail() string { return e.detail }