prevent unicode-confusion in password by applying PRECIS, and username/email address by applying unicode NFC normalization

an é (e with accent) can also be written as e+\u0301. the first form is NFC,
the second NFD. when logging in, we transform usernames (email addresses) to
NFC. so both forms will be accepted. if a client is using NFD, they can log
in too.

for passwords, we apply the PRECIS "opaquestring", which (despite the name)
transforms the value too: unicode spaces are replaced with ascii spaces. the
string is also normalized to NFC. PRECIS may reject confusing passwords when
you set a password.
This commit is contained in:
Mechiel Lukkien
2024-03-08 23:29:15 +01:00
parent 8e6fe7459b
commit c57aeac7f0
99 changed files with 59625 additions and 114 deletions

View File

@ -11,6 +11,7 @@ import (
"time"
"golang.org/x/crypto/bcrypt"
"golang.org/x/text/secure/precis"
"github.com/mjl-/mox/mlog"
"github.com/mjl-/mox/mox-"
@ -48,6 +49,11 @@ func (a *adminSessionAuth) login(ctx context.Context, log mlog.Log, username, pa
return false, "", fmt.Errorf("reading password file: %v", err)
}
passwordhash := strings.TrimSpace(string(buf))
// Transform with precis, if valid. ../rfc/8265:679
pw, err := precis.OpaqueString.String(password)
if err == nil {
password = pw
}
if err := bcrypt.CompareHashAndPassword([]byte(passwordhash), []byte(password)); err != nil {
return false, "", nil
}