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Locking access of entries in auth_server_static #4345

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Merged
demmer merged 2 commits into from
Nov 14, 2018
Merged

Locking access of entries in auth_server_static #4345

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5482b2a
Atomic handling of loadConfig
avaidyanatha Nov 7, 2018
8f34775
Rollback on rotation, mutex updates
avaidyanatha Nov 13, 2018
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30 changes: 7 additions & 23 deletions go/mysql/auth_server_static.go
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Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,6 @@ import (
"os/signal"
"sync"
"syscall"
"time"

"vitess.io/vitess/go/vt/log"
querypb "vitess.io/vitess/go/vt/proto/query"
Expand All @@ -36,7 +35,6 @@ import (
var (
mysqlAuthServerStaticFile = flag.String("mysql_auth_server_static_file", "", "JSON File to read the users/passwords from.")
mysqlAuthServerStaticString = flag.String("mysql_auth_server_static_string", "", "JSON representation of the users/passwords config.")
mysqlAuthRotationTime = flag.Duration("mysql_auth_rotation_time", 300*time.Second, "Cooldown period before reloading json config.")
)

const (
Expand All @@ -54,8 +52,7 @@ type AuthServerStatic struct {
// This mutex helps us prevent data races between the multiple updates of Entries.
mu sync.Mutex
// Entries contains the users, passwords and user data.
Entries map[string][]*AuthServerStaticEntry
LastAuthRotation time.Time
Entries map[string][]*AuthServerStaticEntry
}

// AuthServerStaticEntry stores the values for a given user.
Expand Down Expand Up @@ -116,15 +113,11 @@ func RegisterAuthServerStaticFromParams(file, str string) {
}
authServerStatic.installSignalHandlers()

authServerStatic.LastAuthRotation = time.Now()

// And register the server.
RegisterAuthServerImpl("static", authServerStatic)
}

func (a *AuthServerStatic) loadConfigFromParams(file, str string) {
a.mu.Lock()
defer a.mu.Unlock()
jsonConfig := []byte(str)
if file != "" {
data, err := ioutil.ReadFile(file)
Expand All @@ -135,13 +128,15 @@ func (a *AuthServerStatic) loadConfigFromParams(file, str string) {
jsonConfig = data
}

entries := make(map[string][]*AuthServerStaticEntry) // clear old entries
entries := make(map[string][]*AuthServerStaticEntry)
if err := parseConfig(jsonConfig, &entries); err != nil {
log.Errorf("Error parsing auth server config: %v", err)
return
}

a.mu.Lock()
a.Entries = entries
a.mu.Unlock()
}

func (a *AuthServerStatic) installSignalHandlers() {
Expand Down Expand Up @@ -204,18 +199,9 @@ func (a *AuthServerStatic) Salt() ([]byte, error) {

// ValidateHash is part of the AuthServer interface.
func (a *AuthServerStatic) ValidateHash(salt []byte, user string, authResponse []byte, remoteAddr net.Addr) (Getter, error) {
// If enough time has elpased (default is 5 minutes), reload the auth file/string
if time.Now().Sub(a.LastAuthRotation) > *mysqlAuthRotationTime {
a.loadConfigFromParams(*mysqlAuthServerStaticFile, *mysqlAuthServerStaticString)
a.LastAuthRotation = time.Now()
}

// We lock after the call to loadConfigFromParams since we lock and unlock the mutex within loadConfig.
// This avoids deadlocking, but a cleaner approach could be used.
a.mu.Lock()
defer a.mu.Unlock()
// Find the entry.
entries, ok := a.Entries[user]
a.mu.Unlock()

if !ok {
return &StaticUserData{""}, NewSQLError(ERAccessDeniedError, SSAccessDeniedError, "Access denied for user '%v'", user)
Expand All @@ -242,16 +228,14 @@ func (a *AuthServerStatic) ValidateHash(salt []byte, user string, authResponse [
// We only recognize MysqlClearPassword and MysqlDialog here.
func (a *AuthServerStatic) Negotiate(c *Conn, user string, remoteAddr net.Addr) (Getter, error) {
// Finish the negotiation.
a.mu.Lock()
defer a.mu.Unlock()
password, err := AuthServerNegotiateClearOrDialog(c, a.Method)
if err != nil {
return nil, err
}

// Find the entry.

a.mu.Lock()
entries, ok := a.Entries[user]
a.mu.Unlock()

if !ok {
return &StaticUserData{""}, NewSQLError(ERAccessDeniedError, SSAccessDeniedError, "Access denied for user '%v'", user)
Expand Down