backport of commit f15715f

changelog/19591.txt

@@ -0,0 +1,3 @@
+```release-note:improvement
+core: validate name identifiers in mssql physical storage backend prior use 
+```

physical/mssql/mssql.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"database/sql"
 	"fmt"
+	"regexp"
 	"sort"
 	"strconv"
 	"strings"
@@ -18,6 +19,7 @@ import (
 
 // Verify MSSQLBackend satisfies the correct interfaces
 var _ physical.Backend = (*MSSQLBackend)(nil)
+var identifierRegex = regexp.MustCompile(`^[\p{L}_][\p{L}\p{Nd}@#$_]*$`)
 
 type MSSQLBackend struct {
 	dbTable    string
@@ -27,6 +29,13 @@ type MSSQLBackend struct {
 	permitPool *physical.PermitPool
 }
 
+func isInvalidIdentifier(name string) bool {
+	if !identifierRegex.MatchString(name) {
+		return true
+	}
+	return false
+}
+
 func NewMSSQLBackend(conf map[string]string, logger log.Logger) (physical.Backend, error) {
 	username, ok := conf["username"]
 	if !ok {
@@ -68,11 +77,19 @@ func NewMSSQLBackend(conf map[string]string, logger log.Logger) (physical.Backen
 		database = "Vault"
 	}
 
+	if isInvalidIdentifier(database) {
+		return nil, fmt.Errorf("invalid database name")
+	}
+
 	table, ok := conf["table"]
 	if !ok {
 		table = "Vault"
 	}
 
+	if isInvalidIdentifier(table) {
+		return nil, fmt.Errorf("invalid table name")
+	}
+
 	appname, ok := conf["appname"]
 	if !ok {
 		appname = "Vault"
@@ -93,6 +110,10 @@ func NewMSSQLBackend(conf map[string]string, logger log.Logger) (physical.Backen
 		schema = "dbo"
 	}
 
+	if isInvalidIdentifier(schema) {
+		return nil, fmt.Errorf("invalid schema name")
+	}
+
 	connectionString := fmt.Sprintf("server=%s;app name=%s;connection timeout=%s;log=%s", server, appname, connectionTimeout, logLevel)
 	if username != "" {
 		connectionString += ";user id=" + username
@@ -113,18 +134,17 @@ func NewMSSQLBackend(conf map[string]string, logger log.Logger) (physical.Backen
 
 	db.SetMaxOpenConns(maxParInt)
 
-	if _, err := db.Exec("IF NOT EXISTS(SELECT * FROM sys.databases WHERE name = '" + database + "') CREATE DATABASE " + database); err != nil {
+	if _, err := db.Exec("IF NOT EXISTS(SELECT * FROM sys.databases WHERE name = ?) CREATE DATABASE "+database, database); err != nil {
 		return nil, fmt.Errorf("failed to create mssql database: %w", err)
 	}
 
 	dbTable := database + "." + schema + "." + table
-	createQuery := "IF NOT EXISTS(SELECT 1 FROM " + database + ".INFORMATION_SCHEMA.TABLES WHERE TABLE_TYPE='BASE TABLE' AND TABLE_NAME='" + table + "' AND TABLE_SCHEMA='" + schema +
-		"') CREATE TABLE " + dbTable + " (Path VARCHAR(512) PRIMARY KEY, Value VARBINARY(MAX))"
+	createQuery := "IF NOT EXISTS(SELECT 1 FROM " + database + ".INFORMATION_SCHEMA.TABLES WHERE TABLE_TYPE='BASE TABLE' AND TABLE_NAME=? AND TABLE_SCHEMA=?) CREATE TABLE " + dbTable + " (Path VARCHAR(512) PRIMARY KEY, Value VARBINARY(MAX))"
 
 	if schema != "dbo" {
 
 		var num int
-		err = db.QueryRow("SELECT 1 FROM " + database + ".sys.schemas WHERE name = '" + schema + "'").Scan(&num)
+		err = db.QueryRow("SELECT 1 FROM "+database+".sys.schemas WHERE name = ?", schema).Scan(&num)
 
 		switch {
 		case err == sql.ErrNoRows:
@@ -137,7 +157,7 @@ func NewMSSQLBackend(conf map[string]string, logger log.Logger) (physical.Backen
 		}
 	}
 
-	if _, err := db.Exec(createQuery); err != nil {
+	if _, err := db.Exec(createQuery, table, schema); err != nil {
 		return nil, fmt.Errorf("failed to create mssql table: %w", err)
 	}
 

physical/mssql/mssql_test.go

@@ -4,13 +4,53 @@ import (
 	"os"
 	"testing"
 
+	_ "github.com/denisenkom/go-mssqldb"
 	log "github.com/hashicorp/go-hclog"
 	"github.com/hashicorp/vault/sdk/helper/logging"
 	"github.com/hashicorp/vault/sdk/physical"
-
-	_ "github.com/denisenkom/go-mssqldb"
 )
 
+// TestInvalidIdentifier checks validity of an identifier
+func TestInvalidIdentifier(t *testing.T) {
+	testcases := map[string]bool{
+		"name":             true,
+		"_name":            true,
+		"Name":             true,
+		"#name":            false,
+		"?Name":            false,
+		"9name":            false,
+		"@name":            false,
+		"$name":            false,
+		" name":            false,
+		"n ame":            false,
+		"n4444444":         true,
+		"_4321098765":      true,
+		"_##$$@@__":        true,
+		"_123name#@":       true,
+		"name!":            false,
+		"name%":            false,
+		"name^":            false,
+		"name&":            false,
+		"name*":            false,
+		"name(":            false,
+		"name)":            false,
+		"nåame":            true,
+		"åname":            true,
+		"name'":            false,
+		"nam`e":            false,
+		"пример":           true,
+		"_#Āā@#$_ĂĄąćĈĉĊċ": true,
+		"ÛÜÝÞßàáâ":         true,
+		"豈更滑a23$#@":        true,
+	}
+
+	for i, expected := range testcases {
+		if !isInvalidIdentifier(i) != expected {
+			t.Fatalf("unexpected identifier %s: expected validity %v", i, expected)
+		}
+	}
+}
+
 func TestMSSQLBackend(t *testing.T) {
 	server := os.Getenv("MSSQL_SERVER")
 	if server == "" {