Add initial implementation of grants

internal/dis/component.go

@@ -20,6 +20,7 @@ func (dis *Distillery) init() {
 		lazy.RegisterPoolGroup[component.Provisionable](&dis.pool)
 		lazy.RegisterPoolGroup[component.Routeable](&dis.pool)
 		lazy.RegisterPoolGroup[component.Cronable](&dis.pool)
+		lazy.RegisterPoolGroup[component.UserDeleteHook](&dis.pool)
 	})
 }
 

internal/dis/component/auth/auth.go

@@ -15,7 +15,8 @@ import (
 type Auth struct {
 	component.Base
 	Dependencies struct {
-		SQL *sql.SQL
+		SQL             *sql.SQL
+		UserDeleteHooks []component.UserDeleteHook
 	}
 
 	store lazy.Lazy[sessions.Store]

internal/dis/component/auth/permission.go

@@ -0,0 +1,70 @@
+package auth
+
+import (
+	"errors"
+	"net/http"
+)
+
+// Permission represents a permission granted to a user.
+//
+// The nil permission represents any authenticated user.
+type Permission func(user *AuthUser, r *http.Request) (ok Grant, err error)
+
+// Grant represents an object that either grants or denies access for a certain permission
+type Grant interface {
+	isGranted()
+
+	// Granted returns a boolean indicating if permission to the resource in question
+	// has been granted
+	Granted() bool
+
+	// Denied returns a string containing an error message to display to the user when permission is denied.
+	// When Granted() returns true, the behaviour is undefined.
+	Denied() string
+}
+
+// Bool2Grant returns a new grant that returns granted for the given boolean, and message as the denied message.
+func Bool2Grant(granted bool, message string) Grant {
+	if granted {
+		return grantAllow{}
+	}
+	return grantDeny(message)
+}
+
+type grantAllow struct{}
+
+func (grantAllow) isGranted()     {}
+func (grantAllow) Granted() bool  { return true }
+func (grantAllow) Denied() string { return "" }
+
+type grantDeny string
+
+func (grantDeny) isGranted()      {}
+func (g grantDeny) Granted() bool { return false }
+func (g grantDeny) Denied() string {
+	if g == "" {
+		return "Forbidden"
+	}
+	return string(g)
+}
+
+var errPermissionPanic = errors.New("permission: panic()")
+
+// Permit checks if the given user has this permission.
+func (perm Permission) Permit(user *AuthUser, r *http.Request) (ok Grant, err error) {
+	// if there is no permission, then we just check if there is some user
+	if perm == nil {
+		return Bool2Grant(user != nil, ""), nil
+	}
+
+	// recover any panic()ed permission call
+	// to prevent the handler from panic()ing
+	defer func() {
+		if p := recover(); p != nil {
+			ok = Bool2Grant(false, "unknown error")
+			err = errPermissionPanic
+		}
+	}()
+
+	return perm(user, r)
+}

internal/dis/component/auth/policy/grants.go

@@ -0,0 +1,123 @@
+package policy
+
+import (
+	"context"
+	"errors"
+
+	"github.com/FAU-CDI/wisski-distillery/internal/models"
+	"gorm.io/gorm/clause"
+)
+
+var (
+	ErrNoAccess = errors.New("no access")
+	ErrInvalid  = errors.New("invalid parameters")
+)
+
+// Set sets a specific grant, overwriting a previous grant (if any)
+func (policy *Policy) Set(ctx context.Context, grant models.Grant) error {
+	if grant.User == "" || grant.Slug == "" || grant.DrupalUsername == "" {
+		return ErrInvalid
+	}
+
+	// get the table
+	table, err := policy.table(ctx)
+	if err != nil {
+		return err
+	}
+
+	// and create or update the given user / slug combination
+	return table.Clauses(clause.OnConflict{
+		Columns:   []clause.Column{{Name: "user"}, {Name: "slug"}},
+		DoUpdates: clause.AssignmentColumns([]string{"drupal_user", "admin"}),
+	}).Create(&grant).Error
+}
+
+// Remove removes access for the given username form the given instance.
+// The user not having access is not an error.
+func (policy *Policy) Remove(ctx context.Context, username string, slug string) error {
+	// empty username or slug never have acccess
+	if username == "" || slug == "" {
+		return ErrInvalid
+	}
+
+	// get the table
+	table, err := policy.table(ctx)
+	if err != nil {
+		return err
+	}
+
+	// delete the access from the database
+	return table.Delete(&models.Grant{}, models.Grant{User: username, Slug: slug}).Error
+}
+
+// User returns all grants for the given user
+func (policy *Policy) User(ctx context.Context, username string) (grants []models.Grant, err error) {
+	if username == "" {
+		return nil, ErrInvalid
+	}
+
+	// get the table
+	table, err := policy.table(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	// find the grants
+	err = table.Find(&grants, models.Grant{User: username}).Error
+	if err != nil {
+		return nil, err
+	}
+	return grants, nil
+}
+
+// Instance returns all the grants for the given instance
+func (policy *Policy) Instance(ctx context.Context, slug string) (grants []models.Grant, err error) {
+	if slug == "" {
+		return nil, ErrInvalid
+	}
+
+	// get the table
+	table, err := policy.table(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	// find the grants
+	err = table.Find(&grants, models.Grant{Slug: slug}).Error
+	if err != nil {
+		return nil, err
+	}
+	return grants, nil
+}
+
+// Has checks if the given username has access to the given instance.
+// If the user has access, returns the provided grant.
+//
+// If the user does not have access, returns ErrNoAccess.
+// Other errors may be returned in other cases.
+func (policy *Policy) Has(ctx context.Context, username string, slug string) (grant models.Grant, err error) {
+	// empty username or slug never have acccess
+	if username == "" || slug == "" {
+		return grant, ErrInvalid
+	}
+
+	// get the table
+	table, err := policy.table(ctx)
+	if err != nil {
+		return grant, err
+	}
+
+	// read the access from the database
+	res := table.Find(&grant, models.Grant{User: username, Slug: slug})
+	if err := res.Error; err != nil {
+		return grant, err
+	}
+
+	// if there were no rows affected, then there was no access granted
+	if res.RowsAffected == 0 {
+		return grant, ErrNoAccess
+	}
+
+	// return the username and admin
+	return grant, nil
+}

internal/dis/component/auth/policy/info.go

@@ -0,0 +1 @@
+package policy

internal/dis/component/auth/policy/policy.go

@@ -0,0 +1,27 @@
+package policy
+
+import (
+	"context"
+
+	"github.com/FAU-CDI/wisski-distillery/internal/dis/component"
+	"github.com/FAU-CDI/wisski-distillery/internal/dis/component/sql"
+	"github.com/FAU-CDI/wisski-distillery/internal/models"
+	"gorm.io/gorm"
+)
+
+type Policy struct {
+	component.Base
+
+	Dependencies struct {
+		SQL *sql.SQL
+	}
+}
+
+var (
+	_ component.Provisionable  = (*Policy)(nil)
+	_ component.UserDeleteHook = (*Policy)(nil)
+)
+
+func (pol *Policy) table(ctx context.Context) (*gorm.DB, error) {
+	return pol.Dependencies.SQL.QueryTable(ctx, true, models.GrantTable)
+}

internal/dis/component/auth/policy/purge.go

@@ -0,0 +1,30 @@
+package policy
+
+import (
+	"context"
+
+	"github.com/FAU-CDI/wisski-distillery/internal/models"
+)
+
+func (*Policy) Provision(ctx context.Context, instance models.Instance, domain string) error {
+	// component is purge-only
+	return nil
+}
+
+// Purge purges every policy for the given slug form the database
+func (pol *Policy) Purge(ctx context.Context, instance models.Instance, domain string) error {
+	table, err := pol.table(ctx)
+	if err != nil {
+		return err
+	}
+	return table.Delete(&models.Grant{}, &models.Grant{Slug: instance.Slug}).Error
+}
+
+// OnUserDelete is called when a user is deleted
+func (pol *Policy) OnUserDelete(ctx context.Context, user *models.User) error {
+	table, err := pol.table(ctx)
+	if err != nil {
+		return err
+	}
+	return table.Delete(&models.Grant{}, &models.Grant{User: user.User}).Error
+}

internal/dis/component/auth/protect.go

@@ -2,77 +2,12 @@ package auth
 
 import (
 	"context"
-	"errors"
 	"net/http"
 	"net/url"
 
 	"github.com/FAU-CDI/wisski-distillery/pkg/httpx"
 )
 
-// Permission represents a permission granted to a user.
-//
-// The nil permission represents any authenticated user.
-type Permission func(user *AuthUser, r *http.Request) (ok Grant, err error)
-
-// Grant represents an object that either grants or denies access for a certain permission
-type Grant interface {
-	isGranted()
-
-	// Granted returns a boolean indicating if permission to the resource in question
-	// has been granted
-	Granted() bool
-
-	// Denied returns a string containing an error message to display to the user when permission is denied.
-	// When Granted() returns true, the behaviour is undefined.
-	Denied() string
-}
-
-// Bool2Grant returns a new grant that returns granted for the given boolean, and message as the denied message.
-func Bool2Grant(granted bool, message string) Grant {
-	if granted {
-		return grantAllow{}
-	}
-	return grantDeny(message)
-}
-
-type grantAllow struct{}
-
-func (grantAllow) isGranted()     {}
-func (grantAllow) Granted() bool  { return true }
-func (grantAllow) Denied() string { return "" }
-
-type grantDeny string
-
-func (grantDeny) isGranted()      {}
-func (g grantDeny) Granted() bool { return false }
-func (g grantDeny) Denied() string {
-	if g == "" {
-		return "Forbidden"
-	}
-	return string(g)
-}
-
-var errPermissionPanic = errors.New("permission: panic()")
-
-// Permit checks if the given user has this permission.
-func (perm Permission) Permit(user *AuthUser, r *http.Request) (ok Grant, err error) {
-	// if there is no permission, then we just check if there is some user
-	if perm == nil {
-		return Bool2Grant(user != nil, ""), nil
-	}
-
-	// recover any panic()ed permission call
-	// to prevent the handler from panic()ing
-	defer func() {
-		if p := recover(); p != nil {
-			ok = Bool2Grant(false, "unknown error")
-			err = errPermissionPanic
-		}
-	}()
-
-	return perm(user, r)
-}
-
 // Protect returns a new handler which requires a user to be logged in and pass the perm function.
 //
 // If an unauthenticated user attempts to access the returned handler, they are redirected to the login endpoint.

internal/dis/component/auth/user.go

@@ -278,5 +278,13 @@ func (au *AuthUser) Delete(ctx context.Context) error {
 	if err != nil {
 		return err
 	}
+
+	// run all the user delete hooks
+	for _, c := range au.auth.Dependencies.UserDeleteHooks {
+		if err := c.OnUserDelete(ctx, &au.User); err != nil {
+			return err
+		}
+	}
+
 	return table.Delete(&au.User).Error
 }

internal/dis/component/instances/malt/malt.go

@@ -2,6 +2,7 @@ package malt
 
 import (
 	"github.com/FAU-CDI/wisski-distillery/internal/dis/component"
+	"github.com/FAU-CDI/wisski-distillery/internal/dis/component/auth/policy"
 	"github.com/FAU-CDI/wisski-distillery/internal/dis/component/exporter/logger"
 	"github.com/FAU-CDI/wisski-distillery/internal/dis/component/meta"
 	"github.com/FAU-CDI/wisski-distillery/internal/dis/component/sql"
@@ -16,4 +17,5 @@ type Malt struct {
 	SQL         *sql.SQL                 `auto:"true"`
 	Meta        *meta.Meta               `auto:"true"`
 	ExporterLog *logger.Logger           `auto:"true"`
+	Policy      *policy.Policy           `auto:"true"`
 }

internal/dis/component/meta/storage.go

@@ -26,7 +26,7 @@ type Storage struct {
 // Get retrieves metadata with the provided key and deserializes the first one into target.
 // If no metadatum exists, returns [ErrMetadatumNotSet].
 func (s Storage) Get(ctx context.Context, key Key, target any) error {
-	table, err := s.sql.QueryTable(ctx, true, models.AccessTable)
+	table, err := s.sql.QueryTable(ctx, true, models.GrantTable)
 	if err != nil {
 		return err
 	}
@@ -55,7 +55,7 @@ func (s Storage) Get(ctx context.Context, key Key, target any) error {
 //
 // When no metadatum exists, targets is not called, and nil error is returned.
 func (s Storage) GetAll(ctx context.Context, key Key, target func(index, total int) any) error {
-	table, err := s.sql.QueryTable(ctx, true, models.AccessTable)
+	table, err := s.sql.QueryTable(ctx, true, models.GrantTable)
 	if err != nil {
 		return err
 	}
@@ -82,7 +82,7 @@ func (s Storage) GetAll(ctx context.Context, key Key, target func(index, total i
 
 // Delete deletes all metadata with the provided key.
 func (s Storage) Delete(ctx context.Context, key Key) error {
-	table, err := s.sql.QueryTable(ctx, true, models.AccessTable)
+	table, err := s.sql.QueryTable(ctx, true, models.GrantTable)
 	if err != nil {
 		return err
 	}
@@ -98,7 +98,7 @@ func (s Storage) Delete(ctx context.Context, key Key) error {
 // Set serializes value and stores it with the provided key.
 // Any other metadata with the same key is deleted.
 func (s Storage) Set(ctx context.Context, key Key, value any) error {
-	table, err := s.sql.QueryTable(ctx, true, models.AccessTable)
+	table, err := s.sql.QueryTable(ctx, true, models.GrantTable)
 	if err != nil {
 		return err
 	}
@@ -133,7 +133,7 @@ func (s Storage) Set(ctx context.Context, key Key, value any) error {
 // Set serializes values and stores them with the provided key.
 // Any other metadata with the same key is deleted.
 func (s Storage) SetAll(ctx context.Context, key Key, values ...any) error {
-	table, err := s.sql.QueryTable(ctx, true, models.AccessTable)
+	table, err := s.sql.QueryTable(ctx, true, models.GrantTable)
 	if err != nil {
 		return err
 	}
@@ -167,7 +167,7 @@ func (s Storage) SetAll(ctx context.Context, key Key, values ...any) error {
 
 // Purge removes all metadata, regardless of key.
 func (s Storage) Purge(ctx context.Context) error {
-	table, err := s.sql.QueryTable(ctx, true, models.AccessTable)
+	table, err := s.sql.QueryTable(ctx, true, models.GrantTable)
 	if err != nil {
 		return err
 	}

internal/dis/component/sql/update.go

@@ -91,7 +91,7 @@ func (sql *SQL) Update(ctx context.Context, progress io.Writer) error {
 		{
 			"metadata",
 			&models.Metadatum{},
-			models.AccessTable,
+			models.GrantTable,
 		},
 		{
 			"snapshot",
@@ -108,6 +108,11 @@ func (sql *SQL) Update(ctx context.Context, progress io.Writer) error {
 			&models.User{},
 			models.UserTable,
 		},
+		{
+			"grant",
+			&models.Grant{},
+			models.GrantTable,
+		},
 	}
 
 	// migrate all of the tables!

internal/dis/component/userdelete.go

@@ -0,0 +1,15 @@
+package component
+
+import (
+	"context"
+
+	"github.com/FAU-CDI/wisski-distillery/internal/models"
+)
+
+// UserDeleteHook represents a hook that is called just before a user is deleted
+type UserDeleteHook interface {
+	Component
+
+	// OnUserDelete is called right before a user is deleted
+	OnUserDelete(ctx context.Context, user *models.User) error
+}

internal/dis/distillery.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/FAU-CDI/wisski-distillery/internal/dis/component"
 	"github.com/FAU-CDI/wisski-distillery/internal/dis/component/auth"
+	"github.com/FAU-CDI/wisski-distillery/internal/dis/component/auth/policy"
 	"github.com/FAU-CDI/wisski-distillery/internal/dis/component/control"
 	"github.com/FAU-CDI/wisski-distillery/internal/dis/component/control/cron"
 	"github.com/FAU-CDI/wisski-distillery/internal/dis/component/control/home"
@@ -127,6 +128,7 @@ func (dis *Distillery) allComponents() []initFunc {
 
 		// auth
 		auto[*auth.Auth],
+		auto[*policy.Policy],
 
 		// instances
 		auto[*instances.Instances],

internal/models/grant.go

@@ -0,0 +1,15 @@
+package models
+
+// GrantTable is the name of the table the 'Grant' model is stored in.
+const GrantTable = "grant"
+
+// Grant represents an access grant to a specific user
+type Grant struct {
+	Pk uint `gorm:"column:pk;primaryKey"`
+
+	User string `gorm:"column:user;not null;uniqueIndex:user_slug"` // (distillery) username
+	Slug string `gorm:"column:slug;not null;uniqueIndex:user_slug"` // (distillery) instance slug
+
+	DrupalUsername  string `gorm:"column:drupal_user;not null"` // drupal username
+	DrupalAdminRole bool   `gorm:"column:admin;not null"`       // drupal admin rights
+}