add support for password validation rules

Fixes #494

config/config.go

@@ -238,6 +238,14 @@ func Init() {
 				},
 				Algo: dataprovider.HashingAlgoBcrypt,
 			},
+			PasswordValidation: dataprovider.PasswordValidation{
+				Admins: dataprovider.PasswordValidationRules{
+					MinEntropy: 0,
+				},
+				Users: dataprovider.PasswordValidationRules{
+					MinEntropy: 0,
+				},
+			},
 			PasswordCaching:           true,
 			UpdateMode:                0,
 			PreferDatabaseCredentials: false,
@@ -1050,6 +1058,8 @@ func setViperDefaults() {
 	viper.SetDefault("data_provider.password_hashing.argon2_options.iterations", globalConf.ProviderConf.PasswordHashing.Argon2Options.Iterations)
 	viper.SetDefault("data_provider.password_hashing.argon2_options.parallelism", globalConf.ProviderConf.PasswordHashing.Argon2Options.Parallelism)
 	viper.SetDefault("data_provider.password_hashing.algo", globalConf.ProviderConf.PasswordHashing.Algo)
+	viper.SetDefault("data_provider.password_validation.admins.min_entropy", globalConf.ProviderConf.PasswordValidation.Admins.MinEntropy)
+	viper.SetDefault("data_provider.password_validation.users.min_entropy", globalConf.ProviderConf.PasswordValidation.Users.MinEntropy)
 	viper.SetDefault("data_provider.password_caching", globalConf.ProviderConf.PasswordCaching)
 	viper.SetDefault("data_provider.update_mode", globalConf.ProviderConf.UpdateMode)
 	viper.SetDefault("data_provider.skip_natural_keys_validation", globalConf.ProviderConf.SkipNaturalKeysValidation)

dataprovider/admin.go

@@ -11,6 +11,7 @@ import (
 	"strings"
 
 	"github.com/alexedwards/argon2id"
+	passwordvalidator "github.com/wagslane/go-password-validator"
 	"golang.org/x/crypto/bcrypt"
 
 	"github.com/drakkan/sftpgo/v2/util"
@@ -68,6 +69,11 @@ type Admin struct {
 
 func (a *Admin) checkPassword() error {
 	if a.Password != "" && !util.IsStringPrefixInSlice(a.Password, internalHashPwdPrefixes) {
+		if config.PasswordValidation.Admins.MinEntropy > 0 {
+			if err := passwordvalidator.Validate(a.Password, config.PasswordValidation.Admins.MinEntropy); err != nil {
+				return util.NewValidationError(err.Error())
+			}
+		}
 		if config.PasswordHashing.Algo == HashingAlgoBcrypt {
 			pwd, err := bcrypt.GenerateFromPassword([]byte(a.Password), config.PasswordHashing.BcryptOptions.Cost)
 			if err != nil {

dataprovider/dataprovider.go

@@ -39,6 +39,7 @@ import (
 	"github.com/alexedwards/argon2id"
 	"github.com/go-chi/render"
 	"github.com/rs/xid"
+	passwordvalidator "github.com/wagslane/go-password-validator"
 	"golang.org/x/crypto/bcrypt"
 	"golang.org/x/crypto/pbkdf2"
 	"golang.org/x/crypto/ssh"
@@ -171,6 +172,23 @@ type PasswordHashing struct {
 	Algo string `json:"algo" mapstructure:"algo"`
 }
 
+// PasswordValidationRules defines the password validation rules
+type PasswordValidationRules struct {
+	// MinEntropy defines the minimum password entropy.
+	// 0 means disabled, any password will be accepted.
+	// Take a look at the following link for more details
+	// https://github.com/wagslane/go-password-validator#what-entropy-value-should-i-use
+	MinEntropy float64 `json:"min_entropy" mapstructure:"min_entropy"`
+}
+
+// PasswordValidation defines the password validation rules for admins and protocol users
+type PasswordValidation struct {
+	// Password validation rules for SFTPGo admin users
+	Admins PasswordValidationRules `json:"admins" mapstructure:"admins"`
+	// Password validation rules for SFTPGo protocol users
+	Users PasswordValidationRules `json:"users" mapstructure:"users"`
+}
+
 // UserActions defines the action to execute on user create, update, delete.
 type UserActions struct {
 	// Valid values are add, update, delete. Empty slice to disable
@@ -301,6 +319,8 @@ type Config struct {
 	// folder name. These keys are used in URIs for REST API and Web admin. By default only unreserved URI
 	// characters are allowed: ALPHA / DIGIT / "-" / "." / "_" / "~".
 	SkipNaturalKeysValidation bool `json:"skip_natural_keys_validation" mapstructure:"skip_natural_keys_validation"`
+	// PasswordValidation defines the password validation rules
+	PasswordValidation PasswordValidation `json:"password_validation" mapstructure:"password_validation"`
 	// Verifying argon2 passwords has a high memory and computational cost,
 	// by enabling, in memory, password caching you reduce this cost.
 	PasswordCaching bool `json:"password_caching" mapstructure:"password_caching"`
@@ -1424,6 +1444,11 @@ func validateBaseParams(user *User) error {
 
 func createUserPasswordHash(user *User) error {
 	if user.Password != "" && !user.IsPasswordHashed() {
+		if config.PasswordValidation.Users.MinEntropy > 0 {
+			if err := passwordvalidator.Validate(user.Password, config.PasswordValidation.Users.MinEntropy); err != nil {
+				return util.NewValidationError(err.Error())
+			}
+		}
 		if config.PasswordHashing.Algo == HashingAlgoBcrypt {
 			pwd, err := bcrypt.GenerateFromPassword([]byte(user.Password), config.PasswordHashing.BcryptOptions.Cost)
 			if err != nil {

docs/full-configuration.md

@@ -193,6 +193,11 @@ The configuration file contains the following sections:
     - `bcrypt_options`, struct containing the options for bcrypt hashing algorithm
       - `cost`, integer between 4 and 31. Default: 10
     - `algo`, string. Algorithm to use for hashing passwords. Available algorithms: `argon2id`, `bcrypt`. For bcrypt hashing we use the `$2a$` prefix. Default: `bcrypt`
+  - `password_validation` struct. It defines the password validation rules for admins and protocol users.
+    - `admins`, struct. It defines the password validation rules for SFTPGo admins.
+      - `min_entropy`, float. Defines the minimum password entropy. Take a looke [here](https://github.com/wagslane/go-password-validator#what-entropy-value-should-i-use) for more details. `0` means disabled, any password will be accepted. Default: `0`.
+    - `users`, struct. It defines the password validation rules for SFTPGo protocol users.
+      - `min_entropy`, float. Default: `0`.
   - `password_caching`, boolean. Verifying argon2id passwords has a high memory and computational cost, verifying bcrypt passwords has a high computational cost, by enabling, in memory, password caching you reduce these costs. Default: `true`
   - `update_mode`, integer. Defines how the database will be initialized/updated. 0 means automatically. 1 means manually using the initprovider sub-command.
   - `skip_natural_keys_validation`, boolean. If `true` you can use any UTF-8 character for natural keys as username, admin name, folder name. These keys are used in URIs for REST API and Web admin. If `false` only unreserved URI characters are allowed: ALPHA / DIGIT / "-" / "." / "_" / "~". Default: `false`.

go.mod

@@ -7,7 +7,7 @@ require (
 	github.com/Azure/azure-storage-blob-go v0.14.0
 	github.com/GehirnInc/crypt v0.0.0-20200316065508-bb7000b8a962
 	github.com/alexedwards/argon2id v0.0.0-20210511081203-7d35d68092b8
-	github.com/aws/aws-sdk-go v1.40.15
+	github.com/aws/aws-sdk-go v1.40.16
 	github.com/cockroachdb/cockroach-go/v2 v2.1.1
 	github.com/eikenb/pipeat v0.0.0-20210603033007-44fc3ffce52b
 	github.com/fatih/color v1.12.0 // indirect
@@ -53,6 +53,7 @@ require (
 	github.com/spf13/viper v1.8.1
 	github.com/stretchr/testify v1.7.0
 	github.com/studio-b12/gowebdav v0.0.0-20210630100626-7ff61aa87be8
+	github.com/wagslane/go-password-validator v0.3.0
 	github.com/yl2chen/cidranger v1.0.2
 	go.etcd.io/bbolt v1.3.6
 	go.uber.org/automaxprocs v1.4.0
@@ -62,8 +63,8 @@ require (
 	golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c
 	golang.org/x/time v0.0.0-20210723032227-1f47c861a9ac
 	google.golang.org/api v0.52.0
-	google.golang.org/genproto v0.0.0-20210804223703-f1db76f3300d // indirect
+	google.golang.org/genproto v0.0.0-20210805201207-89edb61ffb67 // indirect
-	google.golang.org/grpc v1.39.0
+	google.golang.org/grpc v1.39.1
 	google.golang.org/protobuf v1.27.1
 	gopkg.in/natefinch/lumberjack.v2 v2.0.0
 )

go.sum

@@ -118,8 +118,8 @@ github.com/aws/aws-sdk-go v1.15.27/go.mod h1:mFuSZ37Z9YOHbQEwBWztmVzqXrEkub65tZo
 github.com/aws/aws-sdk-go v1.23.20/go.mod h1:KmX6BPdI08NWTb3/sm4ZGu5ShLoqVDhKgpiN924inxo=
 github.com/aws/aws-sdk-go v1.38.35/go.mod h1:hcU610XS61/+aQV88ixoOzUoG7v3b31pl2zKMmprdro=
 github.com/aws/aws-sdk-go v1.38.68/go.mod h1:hcU610XS61/+aQV88ixoOzUoG7v3b31pl2zKMmprdro=
-github.com/aws/aws-sdk-go v1.40.15 h1:aqQCwW8meVzLCacWX8NEPg8bBkL0ZlcMSbhwrsg6eNE=
+github.com/aws/aws-sdk-go v1.40.16 h1:Tgg7i9ee2j6ir2EfejPDJBB3PyfUM4dPlvmMLtvJVfo=
-github.com/aws/aws-sdk-go v1.40.15/go.mod h1:585smgzpB/KqRA+K3y/NL/oYRqQvpNJYvLm+LY1U59Q=
+github.com/aws/aws-sdk-go v1.40.16/go.mod h1:585smgzpB/KqRA+K3y/NL/oYRqQvpNJYvLm+LY1U59Q=
 github.com/aws/aws-sdk-go-v2 v1.7.0/go.mod h1:tb9wi5s61kTDA5qCkcDbt3KRVV74GGslQkl/DRdX/P4=
 github.com/aws/aws-sdk-go-v2/service/cloudwatch v1.5.0/go.mod h1:acH3+MQoiMzozT/ivU+DbRg7Ooo2298RdRaWcOv+4vM=
 github.com/aws/smithy-go v1.5.0/go.mod h1:SObp3lf9smib00L/v3U2eAKG8FyQ7iLrJnQiAmR5n+E=
@@ -713,6 +713,8 @@ github.com/tklauser/numcpus v0.2.3 h1:nQ0QYpiritP6ViFhrKYsiv6VVxOpum2Gks5GhnJbS/
 github.com/tklauser/numcpus v0.2.3/go.mod h1:vpEPS/JC+oZGGQ/My/vJnNsvMDQL6PwOqt8dsCw5j+E=
 github.com/ugorji/go v1.1.7/go.mod h1:kZn38zHttfInRq0xu/PH0az30d+z6vm202qpg1oXVMw=
 github.com/ugorji/go/codec v1.1.7/go.mod h1:Ax+UKWsSmolVDwsd+7N3ZtXu+yMGCf907BLYF3GoBXY=
+github.com/wagslane/go-password-validator v0.3.0 h1:vfxOPzGHkz5S146HDpavl0cw1DSVP061Ry2PX0/ON6I=
+github.com/wagslane/go-password-validator v0.3.0/go.mod h1:TI1XJ6T5fRdRnHqHt14pvy1tNVnrwe7m3/f1f2fDphQ=
 github.com/yl2chen/cidranger v1.0.2 h1:lbOWZVCG1tCRX4u24kuM1Tb4nHqWkDxwLdoS+SevawU=
 github.com/yl2chen/cidranger v1.0.2/go.mod h1:9U1yz7WPYDwf0vpNWFaeRh0bjwz5RVgRy/9UEQfHl0g=
 github.com/yuin/goldmark v1.1.25/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
@@ -1085,8 +1087,8 @@ google.golang.org/genproto v0.0.0-20210624174822-c5cf32407d0a/go.mod h1:SzzZ/N+n
 google.golang.org/genproto v0.0.0-20210624195500-8bfb893ecb84/go.mod h1:SzzZ/N+nwJDaO1kznhnlzqS8ocJICar6hYhVyhi++24=
 google.golang.org/genproto v0.0.0-20210721163202-f1cecdd8b78a/go.mod h1:ob2IJxKrgPT52GcgX759i1sleT07tiKowYBGbczaW48=
 google.golang.org/genproto v0.0.0-20210722135532-667f2b7c528f/go.mod h1:ob2IJxKrgPT52GcgX759i1sleT07tiKowYBGbczaW48=
-google.golang.org/genproto v0.0.0-20210804223703-f1db76f3300d h1:Y9fT4WNRxuD0qofEPeWJwNC5kYLBcSXx0m91zyCMzYY=
+google.golang.org/genproto v0.0.0-20210805201207-89edb61ffb67 h1:VmMSf20ssFK0+u1dscyTH9bU4/M4y+X/xNfkvD6kGtM=
-google.golang.org/genproto v0.0.0-20210804223703-f1db76f3300d/go.mod h1:ob2IJxKrgPT52GcgX759i1sleT07tiKowYBGbczaW48=
+google.golang.org/genproto v0.0.0-20210805201207-89edb61ffb67/go.mod h1:ob2IJxKrgPT52GcgX759i1sleT07tiKowYBGbczaW48=
 google.golang.org/grpc v1.8.0/go.mod h1:yo6s7OP7yaDglbqo1J04qKzAhqBH6lvTonzMVmEdcZw=
 google.golang.org/grpc v1.19.0/go.mod h1:mqu4LbDTu4XGKhr4mRzUsmM4RtVoemTSY81AxZiDr8c=
 google.golang.org/grpc v1.20.1/go.mod h1:10oTOabMzJvdu6/UiuZezV6QK5dSlG84ov/aaiqXj38=
@@ -1112,8 +1114,9 @@ google.golang.org/grpc v1.36.1/go.mod h1:qjiiYl8FncCW8feJPdyg3v6XW24KsRHe+dy9BAG
 google.golang.org/grpc v1.37.0/go.mod h1:NREThFqKR1f3iQ6oBuvc5LadQuXVGo9rkm5ZGrQdJfM=
 google.golang.org/grpc v1.37.1/go.mod h1:NREThFqKR1f3iQ6oBuvc5LadQuXVGo9rkm5ZGrQdJfM=
 google.golang.org/grpc v1.38.0/go.mod h1:NREThFqKR1f3iQ6oBuvc5LadQuXVGo9rkm5ZGrQdJfM=
-google.golang.org/grpc v1.39.0 h1:Klz8I9kdtkIN6EpHHUOMLCYhTn/2WAe5a0s1hcBkdTI=
 google.golang.org/grpc v1.39.0/go.mod h1:PImNr+rS9TWYb2O4/emRugxiyHZ5JyHW5F+RPnDzfrE=
+google.golang.org/grpc v1.39.1 h1:f37vZbBVTiJ6jKG5mWz8ySOBxNqy6ViPgyhSdVnxF3E=
+google.golang.org/grpc v1.39.1/go.mod h1:PImNr+rS9TWYb2O4/emRugxiyHZ5JyHW5F+RPnDzfrE=
 google.golang.org/grpc/cmd/protoc-gen-go-grpc v1.1.0/go.mod h1:6Kw0yEErY5E/yWrBtf03jp27GLLJujG4z/JK95pnjjw=
 google.golang.org/protobuf v0.0.0-20200109180630-ec00e32a8dfd/go.mod h1:DFci5gLYBciE7Vtevhsrf46CRTquxDuWsQurQQe4oz8=
 google.golang.org/protobuf v0.0.0-20200221191635-4d8936d0db64/go.mod h1:kwYJMbMJ01Woi6D6+Kah6886xMZcty6N08ah7+eCXa0=

httpd/httpd_test.go

@@ -628,6 +628,44 @@ func TestChangeAdminPassword(t *testing.T) {
 	assert.NoError(t, err)
 }
 
+func TestPasswordValidations(t *testing.T) {
+	if config.GetProviderConf().Driver == dataprovider.MemoryDataProviderName {
+		t.Skip("this test is not supported with the memory provider")
+	}
+	err := dataprovider.Close()
+	assert.NoError(t, err)
+	err = config.LoadConfig(configDir, "")
+	providerConf := config.GetProviderConf()
+	assert.NoError(t, err)
+	providerConf.PasswordValidation.Admins.MinEntropy = 50
+	providerConf.PasswordValidation.Users.MinEntropy = 70
+	err = dataprovider.Initialize(providerConf, configDir, true)
+	assert.NoError(t, err)
+
+	a := getTestAdmin()
+	a.Username = altAdminUsername
+	a.Password = altAdminPassword
+
+	_, resp, err := httpdtest.AddAdmin(a, http.StatusBadRequest)
+	assert.NoError(t, err, string(resp))
+	assert.Contains(t, string(resp), "insecure password")
+
+	_, resp, err = httpdtest.AddUser(getTestUser(), http.StatusBadRequest)
+	assert.NoError(t, err, string(resp))
+	assert.Contains(t, string(resp), "insecure password")
+
+	err = dataprovider.Close()
+	assert.NoError(t, err)
+	err = config.LoadConfig(configDir, "")
+	assert.NoError(t, err)
+	providerConf = config.GetProviderConf()
+	providerConf.CredentialsPath = credentialsPath
+	err = os.RemoveAll(credentialsPath)
+	assert.NoError(t, err)
+	err = dataprovider.Initialize(providerConf, configDir, true)
+	assert.NoError(t, err)
+}
+
 func TestAdminPasswordHashing(t *testing.T) {
 	if config.GetProviderConf().Driver == dataprovider.MemoryDataProviderName {
 		t.Skip("this test is not supported with the memory provider")

sftpgo.json

@@ -179,6 +179,14 @@
       },
       "algo": "bcrypt"
     },
+    "password_validation": {
+      "admins": {
+        "min_entropy": 0
+      },
+      "users": {
+        "min_entropy": 0
+      }
+    },
     "password_caching": true,
     "update_mode": 0,
     "skip_natural_keys_validation": false,