bugfix: Fix a race condition when creating guest accounts (#882)

* bugfix: Fix a race condition when creating guest accounts

It was possible to both select the same next numeric ID and then both
attempt to INSERT this into the table. This would cause a UNIQUE violation
which then presented itself as an error in sqlite because it does not
implement `common.IsUniqueConstraintViolationErr`.

The fix here is NOT to implement `common.IsUniqueConstraintViolationErr`
otherwise the 2 users would get the SAME guest account. Instead, all of
these operations should be done inside a transaction. This is what this
PR does.

* Update postgres

* Typo

* Actually use the txn when creating accounts

* bugfix for database is locked on guest reg
main
Kegsay 2020-03-06 18:00:07 +00:00 committed by GitHub
parent 6a1111c3d4
commit c31cb02271
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
10 changed files with 108 additions and 40 deletions

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@ -30,6 +30,7 @@ type Database interface {
SetAvatarURL(ctx context.Context, localpart string, avatarURL string) error SetAvatarURL(ctx context.Context, localpart string, avatarURL string) error
SetDisplayName(ctx context.Context, localpart string, displayName string) error SetDisplayName(ctx context.Context, localpart string, displayName string) error
CreateAccount(ctx context.Context, localpart, plaintextPassword, appserviceID string) (*authtypes.Account, error) CreateAccount(ctx context.Context, localpart, plaintextPassword, appserviceID string) (*authtypes.Account, error)
CreateGuestAccount(ctx context.Context) (*authtypes.Account, error)
UpdateMemberships(ctx context.Context, eventsToAdd []gomatrixserverlib.Event, idsToRemove []string) error UpdateMemberships(ctx context.Context, eventsToAdd []gomatrixserverlib.Event, idsToRemove []string) error
GetMembershipInRoomByLocalpart(ctx context.Context, localpart, roomID string) (authtypes.Membership, error) GetMembershipInRoomByLocalpart(ctx context.Context, localpart, roomID string) (authtypes.Membership, error)
GetMembershipsByLocalpart(ctx context.Context, localpart string) (memberships []authtypes.Membership, err error) GetMembershipsByLocalpart(ctx context.Context, localpart string) (memberships []authtypes.Membership, err error)

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@ -72,9 +72,9 @@ func (s *accountDataStatements) prepare(db *sql.DB) (err error) {
} }
func (s *accountDataStatements) insertAccountData( func (s *accountDataStatements) insertAccountData(
ctx context.Context, localpart, roomID, dataType, content string, ctx context.Context, txn *sql.Tx, localpart, roomID, dataType, content string,
) (err error) { ) (err error) {
stmt := s.insertAccountDataStmt stmt := txn.Stmt(s.insertAccountDataStmt)
_, err = stmt.ExecContext(ctx, localpart, roomID, dataType, content) _, err = stmt.ExecContext(ctx, localpart, roomID, dataType, content)
return return
} }

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@ -91,10 +91,10 @@ func (s *accountsStatements) prepare(db *sql.DB, server gomatrixserverlib.Server
// this account will be passwordless. Returns an error if this account already exists. Returns the account // this account will be passwordless. Returns an error if this account already exists. Returns the account
// on success. // on success.
func (s *accountsStatements) insertAccount( func (s *accountsStatements) insertAccount(
ctx context.Context, localpart, hash, appserviceID string, ctx context.Context, txn *sql.Tx, localpart, hash, appserviceID string,
) (*authtypes.Account, error) { ) (*authtypes.Account, error) {
createdTimeMS := time.Now().UnixNano() / 1000000 createdTimeMS := time.Now().UnixNano() / 1000000
stmt := s.insertAccountStmt stmt := txn.Stmt(s.insertAccountStmt)
var err error var err error
if appserviceID == "" { if appserviceID == "" {
@ -146,8 +146,12 @@ func (s *accountsStatements) selectAccountByLocalpart(
} }
func (s *accountsStatements) selectNewNumericLocalpart( func (s *accountsStatements) selectNewNumericLocalpart(
ctx context.Context, ctx context.Context, txn *sql.Tx,
) (id int64, err error) { ) (id int64, err error) {
err = s.selectNewNumericLocalpartStmt.QueryRowContext(ctx).Scan(&id) stmt := s.selectNewNumericLocalpartStmt
if txn != nil {
stmt = txn.Stmt(stmt)
}
err = stmt.QueryRowContext(ctx).Scan(&id)
return return
} }

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@ -73,9 +73,9 @@ func (s *profilesStatements) prepare(db *sql.DB) (err error) {
} }
func (s *profilesStatements) insertProfile( func (s *profilesStatements) insertProfile(
ctx context.Context, localpart string, ctx context.Context, txn *sql.Tx, localpart string,
) (err error) { ) (err error) {
_, err = s.insertProfileStmt.ExecContext(ctx, localpart, "", "") _, err = txn.Stmt(s.insertProfileStmt).ExecContext(ctx, localpart, "", "")
return return
} }

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@ -18,6 +18,7 @@ import (
"context" "context"
"database/sql" "database/sql"
"errors" "errors"
"strconv"
"github.com/matrix-org/dendrite/clientapi/auth/authtypes" "github.com/matrix-org/dendrite/clientapi/auth/authtypes"
"github.com/matrix-org/dendrite/common" "github.com/matrix-org/dendrite/common"
@ -118,11 +119,37 @@ func (d *Database) SetDisplayName(
return d.profiles.setDisplayName(ctx, localpart, displayName) return d.profiles.setDisplayName(ctx, localpart, displayName)
} }
// CreateGuestAccount makes a new guest account and creates an empty profile
// for this account.
func (d *Database) CreateGuestAccount(ctx context.Context) (acc *authtypes.Account, err error) {
err = common.WithTransaction(d.db, func(txn *sql.Tx) error {
var numLocalpart int64
numLocalpart, err = d.accounts.selectNewNumericLocalpart(ctx, txn)
if err != nil {
return err
}
localpart := strconv.FormatInt(numLocalpart, 10)
acc, err = d.createAccount(ctx, txn, localpart, "", "")
return err
})
return acc, err
}
// CreateAccount makes a new account with the given login name and password, and creates an empty profile // CreateAccount makes a new account with the given login name and password, and creates an empty profile
// for this account. If no password is supplied, the account will be a passwordless account. If the // for this account. If no password is supplied, the account will be a passwordless account. If the
// account already exists, it will return nil, nil. // account already exists, it will return nil, nil.
func (d *Database) CreateAccount( func (d *Database) CreateAccount(
ctx context.Context, localpart, plaintextPassword, appserviceID string, ctx context.Context, localpart, plaintextPassword, appserviceID string,
) (acc *authtypes.Account, err error) {
err = common.WithTransaction(d.db, func(txn *sql.Tx) error {
acc, err = d.createAccount(ctx, txn, localpart, plaintextPassword, appserviceID)
return err
})
return
}
func (d *Database) createAccount(
ctx context.Context, txn *sql.Tx, localpart, plaintextPassword, appserviceID string,
) (*authtypes.Account, error) { ) (*authtypes.Account, error) {
var err error var err error
@ -134,13 +161,14 @@ func (d *Database) CreateAccount(
return nil, err return nil, err
} }
} }
if err := d.profiles.insertProfile(ctx, localpart); err != nil { if err := d.profiles.insertProfile(ctx, txn, localpart); err != nil {
if common.IsUniqueConstraintViolationErr(err) { if common.IsUniqueConstraintViolationErr(err) {
return nil, nil return nil, nil
} }
return nil, err return nil, err
} }
if err := d.SaveAccountData(ctx, localpart, "", "m.push_rules", `{
if err := d.accountDatas.insertAccountData(ctx, txn, localpart, "", "m.push_rules", `{
"global": { "global": {
"content": [], "content": [],
"override": [], "override": [],
@ -151,7 +179,7 @@ func (d *Database) CreateAccount(
}`); err != nil { }`); err != nil {
return nil, err return nil, err
} }
return d.accounts.insertAccount(ctx, localpart, hash, appserviceID) return d.accounts.insertAccount(ctx, txn, localpart, hash, appserviceID)
} }
// SaveMembership saves the user matching a given localpart as a member of a given // SaveMembership saves the user matching a given localpart as a member of a given
@ -258,7 +286,9 @@ func (d *Database) newMembership(
func (d *Database) SaveAccountData( func (d *Database) SaveAccountData(
ctx context.Context, localpart, roomID, dataType, content string, ctx context.Context, localpart, roomID, dataType, content string,
) error { ) error {
return d.accountDatas.insertAccountData(ctx, localpart, roomID, dataType, content) return common.WithTransaction(d.db, func(txn *sql.Tx) error {
return d.accountDatas.insertAccountData(ctx, txn, localpart, roomID, dataType, content)
})
} }
// GetAccountData returns account data related to a given localpart // GetAccountData returns account data related to a given localpart
@ -288,7 +318,7 @@ func (d *Database) GetAccountDataByType(
func (d *Database) GetNewNumericLocalpart( func (d *Database) GetNewNumericLocalpart(
ctx context.Context, ctx context.Context,
) (int64, error) { ) (int64, error) {
return d.accounts.selectNewNumericLocalpart(ctx) return d.accounts.selectNewNumericLocalpart(ctx, nil)
} }
func hashPassword(plaintext string) (hash string, err error) { func hashPassword(plaintext string) (hash string, err error) {

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@ -72,10 +72,9 @@ func (s *accountDataStatements) prepare(db *sql.DB) (err error) {
} }
func (s *accountDataStatements) insertAccountData( func (s *accountDataStatements) insertAccountData(
ctx context.Context, localpart, roomID, dataType, content string, ctx context.Context, txn *sql.Tx, localpart, roomID, dataType, content string,
) (err error) { ) (err error) {
stmt := s.insertAccountDataStmt _, err = txn.Stmt(s.insertAccountDataStmt).ExecContext(ctx, localpart, roomID, dataType, content)
_, err = stmt.ExecContext(ctx, localpart, roomID, dataType, content)
return return
} }

View File

@ -89,16 +89,16 @@ func (s *accountsStatements) prepare(db *sql.DB, server gomatrixserverlib.Server
// this account will be passwordless. Returns an error if this account already exists. Returns the account // this account will be passwordless. Returns an error if this account already exists. Returns the account
// on success. // on success.
func (s *accountsStatements) insertAccount( func (s *accountsStatements) insertAccount(
ctx context.Context, localpart, hash, appserviceID string, ctx context.Context, txn *sql.Tx, localpart, hash, appserviceID string,
) (*authtypes.Account, error) { ) (*authtypes.Account, error) {
createdTimeMS := time.Now().UnixNano() / 1000000 createdTimeMS := time.Now().UnixNano() / 1000000
stmt := s.insertAccountStmt stmt := s.insertAccountStmt
var err error var err error
if appserviceID == "" { if appserviceID == "" {
_, err = stmt.ExecContext(ctx, localpart, createdTimeMS, hash, nil) _, err = txn.Stmt(stmt).ExecContext(ctx, localpart, createdTimeMS, hash, nil)
} else { } else {
_, err = stmt.ExecContext(ctx, localpart, createdTimeMS, hash, appserviceID) _, err = txn.Stmt(stmt).ExecContext(ctx, localpart, createdTimeMS, hash, appserviceID)
} }
if err != nil { if err != nil {
return nil, err return nil, err
@ -144,8 +144,12 @@ func (s *accountsStatements) selectAccountByLocalpart(
} }
func (s *accountsStatements) selectNewNumericLocalpart( func (s *accountsStatements) selectNewNumericLocalpart(
ctx context.Context, ctx context.Context, txn *sql.Tx,
) (id int64, err error) { ) (id int64, err error) {
err = s.selectNewNumericLocalpartStmt.QueryRowContext(ctx).Scan(&id) stmt := s.selectNewNumericLocalpartStmt
if txn != nil {
stmt = txn.Stmt(stmt)
}
err = stmt.QueryRowContext(ctx).Scan(&id)
return return
} }

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@ -73,9 +73,9 @@ func (s *profilesStatements) prepare(db *sql.DB) (err error) {
} }
func (s *profilesStatements) insertProfile( func (s *profilesStatements) insertProfile(
ctx context.Context, localpart string, ctx context.Context, txn *sql.Tx, localpart string,
) (err error) { ) (err error) {
_, err = s.insertProfileStmt.ExecContext(ctx, localpart, "", "") _, err = txn.Stmt(s.insertProfileStmt).ExecContext(ctx, localpart, "", "")
return return
} }

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@ -18,6 +18,8 @@ import (
"context" "context"
"database/sql" "database/sql"
"errors" "errors"
"strconv"
"sync"
"github.com/matrix-org/dendrite/clientapi/auth/authtypes" "github.com/matrix-org/dendrite/clientapi/auth/authtypes"
"github.com/matrix-org/dendrite/common" "github.com/matrix-org/dendrite/common"
@ -39,6 +41,8 @@ type Database struct {
threepids threepidStatements threepids threepidStatements
filter filterStatements filter filterStatements
serverName gomatrixserverlib.ServerName serverName gomatrixserverlib.ServerName
createGuestAccountMu sync.Mutex
} }
// NewDatabase creates a new accounts and profiles database // NewDatabase creates a new accounts and profiles database
@ -76,7 +80,7 @@ func NewDatabase(dataSourceName string, serverName gomatrixserverlib.ServerName)
if err = f.prepare(db); err != nil { if err = f.prepare(db); err != nil {
return nil, err return nil, err
} }
return &Database{db, partitions, a, p, m, ac, t, f, serverName}, nil return &Database{db, partitions, a, p, m, ac, t, f, serverName, sync.Mutex{}}, nil
} }
// GetAccountByPassword returns the account associated with the given localpart and password. // GetAccountByPassword returns the account associated with the given localpart and password.
@ -118,14 +122,46 @@ func (d *Database) SetDisplayName(
return d.profiles.setDisplayName(ctx, localpart, displayName) return d.profiles.setDisplayName(ctx, localpart, displayName)
} }
// CreateGuestAccount makes a new guest account and creates an empty profile
// for this account.
func (d *Database) CreateGuestAccount(ctx context.Context) (acc *authtypes.Account, err error) {
err = common.WithTransaction(d.db, func(txn *sql.Tx) error {
// We need to lock so we sequentially create numeric localparts. If we don't, two calls to
// this function will cause the same number to be selected and one will fail with 'database is locked'
// when the first txn upgrades to a write txn.
// We know we'll be the only process since this is sqlite ;) so a lock here will be all that is needed.
d.createGuestAccountMu.Lock()
defer d.createGuestAccountMu.Unlock()
var numLocalpart int64
numLocalpart, err = d.accounts.selectNewNumericLocalpart(ctx, txn)
if err != nil {
return err
}
localpart := strconv.FormatInt(numLocalpart, 10)
acc, err = d.createAccount(ctx, txn, localpart, "", "")
return err
})
return acc, err
}
// CreateAccount makes a new account with the given login name and password, and creates an empty profile // CreateAccount makes a new account with the given login name and password, and creates an empty profile
// for this account. If no password is supplied, the account will be a passwordless account. If the // for this account. If no password is supplied, the account will be a passwordless account. If the
// account already exists, it will return nil, nil. // account already exists, it will return nil, nil.
func (d *Database) CreateAccount( func (d *Database) CreateAccount(
ctx context.Context, localpart, plaintextPassword, appserviceID string, ctx context.Context, localpart, plaintextPassword, appserviceID string,
) (acc *authtypes.Account, err error) {
err = common.WithTransaction(d.db, func(txn *sql.Tx) error {
acc, err = d.createAccount(ctx, txn, localpart, plaintextPassword, appserviceID)
return err
})
return
}
func (d *Database) createAccount(
ctx context.Context, txn *sql.Tx, localpart, plaintextPassword, appserviceID string,
) (*authtypes.Account, error) { ) (*authtypes.Account, error) {
var err error var err error
// Generate a password hash if this is not a password-less user // Generate a password hash if this is not a password-less user
hash := "" hash := ""
if plaintextPassword != "" { if plaintextPassword != "" {
@ -134,13 +170,14 @@ func (d *Database) CreateAccount(
return nil, err return nil, err
} }
} }
if err := d.profiles.insertProfile(ctx, localpart); err != nil { if err := d.profiles.insertProfile(ctx, txn, localpart); err != nil {
if common.IsUniqueConstraintViolationErr(err) { if common.IsUniqueConstraintViolationErr(err) {
return nil, nil return nil, nil
} }
return nil, err return nil, err
} }
if err := d.SaveAccountData(ctx, localpart, "", "m.push_rules", `{
if err := d.accountDatas.insertAccountData(ctx, txn, localpart, "", "m.push_rules", `{
"global": { "global": {
"content": [], "content": [],
"override": [], "override": [],
@ -151,7 +188,7 @@ func (d *Database) CreateAccount(
}`); err != nil { }`); err != nil {
return nil, err return nil, err
} }
return d.accounts.insertAccount(ctx, localpart, hash, appserviceID) return d.accounts.insertAccount(ctx, txn, localpart, hash, appserviceID)
} }
// SaveMembership saves the user matching a given localpart as a member of a given // SaveMembership saves the user matching a given localpart as a member of a given
@ -258,7 +295,9 @@ func (d *Database) newMembership(
func (d *Database) SaveAccountData( func (d *Database) SaveAccountData(
ctx context.Context, localpart, roomID, dataType, content string, ctx context.Context, localpart, roomID, dataType, content string,
) error { ) error {
return d.accountDatas.insertAccountData(ctx, localpart, roomID, dataType, content) return common.WithTransaction(d.db, func(txn *sql.Tx) error {
return d.accountDatas.insertAccountData(ctx, txn, localpart, roomID, dataType, content)
})
} }
// GetAccountData returns account data related to a given localpart // GetAccountData returns account data related to a given localpart
@ -288,7 +327,7 @@ func (d *Database) GetAccountDataByType(
func (d *Database) GetNewNumericLocalpart( func (d *Database) GetNewNumericLocalpart(
ctx context.Context, ctx context.Context,
) (int64, error) { ) (int64, error) {
return d.accounts.selectNewNumericLocalpart(ctx) return d.accounts.selectNewNumericLocalpart(ctx, nil)
} }
func hashPassword(plaintext string) (hash string, err error) { func hashPassword(plaintext string) (hash string, err error) {

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@ -516,16 +516,7 @@ func handleGuestRegistration(
accountDB accounts.Database, accountDB accounts.Database,
deviceDB devices.Database, deviceDB devices.Database,
) util.JSONResponse { ) util.JSONResponse {
acc, err := accountDB.CreateGuestAccount(req.Context())
//Generate numeric local part for guest user
id, err := accountDB.GetNewNumericLocalpart(req.Context())
if err != nil {
util.GetLogger(req.Context()).WithError(err).Error("accountDB.GetNewNumericLocalpart failed")
return jsonerror.InternalServerError()
}
localpart := strconv.FormatInt(id, 10)
acc, err := accountDB.CreateAccount(req.Context(), localpart, "", "")
if err != nil { if err != nil {
return util.JSONResponse{ return util.JSONResponse{
Code: http.StatusInternalServerError, Code: http.StatusInternalServerError,