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Add option to provide signature for a token to verify key ownership (#14054)
* Add option to provide signed token to verify key ownership Currently we will only allow a key to be matched to a user if it matches an activated email address. This PR provides a different mechanism - if the user provides a signature for automatically generated token (based on the timestamp, user creation time, user ID, username and primary email. * Ensure verified keys can act for all active emails for the user * Add code to mark keys as verified * Slight UI adjustments * Slight UI adjustments 2 * Simplify signature verification slightly * fix postgres test * add api routes * handle swapped primary-keys * Verify the no-reply address for verified keys * Only add email addresses that are activated to keys * Fix committer shortcut properly * Restructure gpg_keys.go * Use common Verification Token code Signed-off-by: Andrew Thornton <art27@cantab.net>
This commit is contained in:
zeripath
GitHub
520
models/gpg_key_commit_verification.go
Normal file
520
models/gpg_key_commit_verification.go
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@@ -0,0 +1,520 @@
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// Copyright 2021 The Gitea Authors. All rights reserved.
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// Use of this source code is governed by a MIT-style
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// license that can be found in the LICENSE file.
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package models
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import (
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"container/list"
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"fmt"
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"hash"
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"strings"
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"code.gitea.io/gitea/modules/git"
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"code.gitea.io/gitea/modules/log"
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"code.gitea.io/gitea/modules/setting"
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"github.com/keybase/go-crypto/openpgp/packet"
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)
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// __________________ ________ ____ __.
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// / _____/\______ \/ _____/ | |/ _|____ ___.__.
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// / \ ___ | ___/ \ ___ | <_/ __ < | |
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// \ \_\ \| | \ \_\ \ | | \ ___/\___ |
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// \______ /|____| \______ / |____|__ \___ > ____|
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// \/ \/ \/ \/\/
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// _________ .__ __
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// \_ ___ \ ____ _____ _____ |__|/ |_
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// / \ \/ / _ \ / \ / \| \ __\
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// \ \___( <_> ) Y Y \ Y Y \ || |
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// \______ /\____/|__|_| /__|_| /__||__|
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// \/ \/ \/
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// ____ ____ .__ _____.__ __ .__
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// \ \ / /___________|__|/ ____\__| ____ _____ _/ |_|__| ____ ____
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// \ Y // __ \_ __ \ \ __\| |/ ___\\__ \\ __\ |/ _ \ / \
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// \ /\ ___/| | \/ || | | \ \___ / __ \| | | ( <_> ) | \
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// \___/ \___ >__| |__||__| |__|\___ >____ /__| |__|\____/|___| /
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// \/ \/ \/ \/
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// This file provides functions relating commit verification
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// CommitVerification represents a commit validation of signature
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type CommitVerification struct {
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Verified bool
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Warning bool
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Reason string
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SigningUser *User
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CommittingUser *User
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SigningEmail string
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SigningKey *GPGKey
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TrustStatus string
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}
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// SignCommit represents a commit with validation of signature.
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type SignCommit struct {
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Verification *CommitVerification
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*UserCommit
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}
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const (
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// BadSignature is used as the reason when the signature has a KeyID that is in the db
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// but no key that has that ID verifies the signature. This is a suspicious failure.
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BadSignature = "gpg.error.probable_bad_signature"
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// BadDefaultSignature is used as the reason when the signature has a KeyID that matches the
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// default Key but is not verified by the default key. This is a suspicious failure.
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BadDefaultSignature = "gpg.error.probable_bad_default_signature"
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// NoKeyFound is used as the reason when no key can be found to verify the signature.
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NoKeyFound = "gpg.error.no_gpg_keys_found"
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)
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// ParseCommitsWithSignature checks if signaute of commits are corresponding to users gpg keys.
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func ParseCommitsWithSignature(oldCommits *list.List, repository *Repository) *list.List {
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var (
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newCommits = list.New()
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e = oldCommits.Front()
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)
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keyMap := map[string]bool{}
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for e != nil {
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c := e.Value.(UserCommit)
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signCommit := SignCommit{
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UserCommit: &c,
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Verification: ParseCommitWithSignature(c.Commit),
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}
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_ = CalculateTrustStatus(signCommit.Verification, repository, &keyMap)
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newCommits.PushBack(signCommit)
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e = e.Next()
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}
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return newCommits
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}
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// ParseCommitWithSignature check if signature is good against keystore.
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func ParseCommitWithSignature(c *git.Commit) *CommitVerification {
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var committer *User
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if c.Committer != nil {
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var err error
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// Find Committer account
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committer, err = GetUserByEmail(c.Committer.Email) // This finds the user by primary email or activated email so commit will not be valid if email is not
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if err != nil { // Skipping not user for committer
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committer = &User{
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Name: c.Committer.Name,
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Email: c.Committer.Email,
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}
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// We can expect this to often be an ErrUserNotExist. in the case
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// it is not, however, it is important to log it.
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if !IsErrUserNotExist(err) {
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log.Error("GetUserByEmail: %v", err)
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return &CommitVerification{
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CommittingUser: committer,
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Verified: false,
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Reason: "gpg.error.no_committer_account",
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}
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}
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}
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}
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// If no signature just report the committer
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if c.Signature == nil {
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return &CommitVerification{
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CommittingUser: committer,
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Verified: false, // Default value
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Reason: "gpg.error.not_signed_commit", // Default value
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}
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}
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// Parsing signature
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sig, err := extractSignature(c.Signature.Signature)
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if err != nil { // Skipping failed to extract sign
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log.Error("SignatureRead err: %v", err)
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return &CommitVerification{
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CommittingUser: committer,
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Verified: false,
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Reason: "gpg.error.extract_sign",
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}
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}
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keyID := ""
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if sig.IssuerKeyId != nil && (*sig.IssuerKeyId) != 0 {
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keyID = fmt.Sprintf("%X", *sig.IssuerKeyId)
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}
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if keyID == "" && sig.IssuerFingerprint != nil && len(sig.IssuerFingerprint) > 0 {
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keyID = fmt.Sprintf("%X", sig.IssuerFingerprint[12:20])
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}
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defaultReason := NoKeyFound
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// First check if the sig has a keyID and if so just look at that
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if commitVerification := hashAndVerifyForKeyID(
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sig,
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c.Signature.Payload,
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committer,
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keyID,
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setting.AppName,
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""); commitVerification != nil {
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if commitVerification.Reason == BadSignature {
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defaultReason = BadSignature
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} else {
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return commitVerification
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}
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}
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// Now try to associate the signature with the committer, if present
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if committer.ID != 0 {
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keys, err := ListGPGKeys(committer.ID, ListOptions{})
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if err != nil { // Skipping failed to get gpg keys of user
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log.Error("ListGPGKeys: %v", err)
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return &CommitVerification{
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CommittingUser: committer,
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Verified: false,
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Reason: "gpg.error.failed_retrieval_gpg_keys",
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}
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}
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committerEmailAddresses, _ := GetEmailAddresses(committer.ID)
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activated := false
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for _, e := range committerEmailAddresses {
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if e.IsActivated && strings.EqualFold(e.Email, c.Committer.Email) {
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activated = true
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break
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}
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}
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for _, k := range keys {
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// Pre-check (& optimization) that emails attached to key can be attached to the committer email and can validate
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canValidate := false
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email := ""
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if k.Verified && activated {
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canValidate = true
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email = c.Committer.Email
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}
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if !canValidate {
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for _, e := range k.Emails {
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if e.IsActivated && strings.EqualFold(e.Email, c.Committer.Email) {
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canValidate = true
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email = e.Email
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break
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}
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}
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}
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if !canValidate {
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continue // Skip this key
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}
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commitVerification := hashAndVerifyWithSubKeysCommitVerification(sig, c.Signature.Payload, k, committer, committer, email)
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if commitVerification != nil {
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return commitVerification
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}
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}
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}
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if setting.Repository.Signing.SigningKey != "" && setting.Repository.Signing.SigningKey != "default" && setting.Repository.Signing.SigningKey != "none" {
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// OK we should try the default key
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gpgSettings := git.GPGSettings{
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Sign: true,
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KeyID: setting.Repository.Signing.SigningKey,
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Name: setting.Repository.Signing.SigningName,
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Email: setting.Repository.Signing.SigningEmail,
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}
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if err := gpgSettings.LoadPublicKeyContent(); err != nil {
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log.Error("Error getting default signing key: %s %v", gpgSettings.KeyID, err)
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} else if commitVerification := verifyWithGPGSettings(&gpgSettings, sig, c.Signature.Payload, committer, keyID); commitVerification != nil {
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if commitVerification.Reason == BadSignature {
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defaultReason = BadSignature
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} else {
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return commitVerification
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}
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}
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}
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defaultGPGSettings, err := c.GetRepositoryDefaultPublicGPGKey(false)
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if err != nil {
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log.Error("Error getting default public gpg key: %v", err)
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} else if defaultGPGSettings == nil {
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log.Warn("Unable to get defaultGPGSettings for unattached commit: %s", c.ID.String())
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} else if defaultGPGSettings.Sign {
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if commitVerification := verifyWithGPGSettings(defaultGPGSettings, sig, c.Signature.Payload, committer, keyID); commitVerification != nil {
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if commitVerification.Reason == BadSignature {
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defaultReason = BadSignature
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} else {
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return commitVerification
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}
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}
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}
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return &CommitVerification{ // Default at this stage
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CommittingUser: committer,
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Verified: false,
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Warning: defaultReason != NoKeyFound,
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Reason: defaultReason,
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SigningKey: &GPGKey{
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KeyID: keyID,
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},
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}
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}
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func verifyWithGPGSettings(gpgSettings *git.GPGSettings, sig *packet.Signature, payload string, committer *User, keyID string) *CommitVerification {
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// First try to find the key in the db
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if commitVerification := hashAndVerifyForKeyID(sig, payload, committer, gpgSettings.KeyID, gpgSettings.Name, gpgSettings.Email); commitVerification != nil {
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return commitVerification
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}
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// Otherwise we have to parse the key
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ekeys, err := checkArmoredGPGKeyString(gpgSettings.PublicKeyContent)
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if err != nil {
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log.Error("Unable to get default signing key: %v", err)
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return &CommitVerification{
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CommittingUser: committer,
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Verified: false,
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Reason: "gpg.error.generate_hash",
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}
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}
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for _, ekey := range ekeys {
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pubkey := ekey.PrimaryKey
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content, err := base64EncPubKey(pubkey)
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if err != nil {
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return &CommitVerification{
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CommittingUser: committer,
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Verified: false,
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Reason: "gpg.error.generate_hash",
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}
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}
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k := &GPGKey{
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Content: content,
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CanSign: pubkey.CanSign(),
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KeyID: pubkey.KeyIdString(),
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}
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for _, subKey := range ekey.Subkeys {
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content, err := base64EncPubKey(subKey.PublicKey)
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if err != nil {
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return &CommitVerification{
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CommittingUser: committer,
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Verified: false,
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Reason: "gpg.error.generate_hash",
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}
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}
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k.SubsKey = append(k.SubsKey, &GPGKey{
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Content: content,
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CanSign: subKey.PublicKey.CanSign(),
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KeyID: subKey.PublicKey.KeyIdString(),
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})
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}
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if commitVerification := hashAndVerifyWithSubKeysCommitVerification(sig, payload, k, committer, &User{
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Name: gpgSettings.Name,
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Email: gpgSettings.Email,
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}, gpgSettings.Email); commitVerification != nil {
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return commitVerification
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}
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if keyID == k.KeyID {
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// This is a bad situation ... We have a key id that matches our default key but the signature doesn't match.
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return &CommitVerification{
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CommittingUser: committer,
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Verified: false,
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Warning: true,
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Reason: BadSignature,
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}
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}
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}
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return nil
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}
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func verifySign(s *packet.Signature, h hash.Hash, k *GPGKey) error {
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// Check if key can sign
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if !k.CanSign {
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return fmt.Errorf("key can not sign")
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}
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// Decode key
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pkey, err := base64DecPubKey(k.Content)
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if err != nil {
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return err
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}
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return pkey.VerifySignature(h, s)
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}
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func hashAndVerify(sig *packet.Signature, payload string, k *GPGKey) (*GPGKey, error) {
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// Generating hash of commit
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hash, err := populateHash(sig.Hash, []byte(payload))
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if err != nil { // Skipping as failed to generate hash
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log.Error("PopulateHash: %v", err)
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return nil, err
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}
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// We will ignore errors in verification as they don't need to be propagated up
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err = verifySign(sig, hash, k)
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if err != nil {
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return nil, nil
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}
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return k, nil
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}
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func hashAndVerifyWithSubKeys(sig *packet.Signature, payload string, k *GPGKey) (*GPGKey, error) {
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verified, err := hashAndVerify(sig, payload, k)
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if err != nil || verified != nil {
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return verified, err
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}
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for _, sk := range k.SubsKey {
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verified, err := hashAndVerify(sig, payload, sk)
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if err != nil || verified != nil {
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return verified, err
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}
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}
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return nil, nil
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}
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func hashAndVerifyWithSubKeysCommitVerification(sig *packet.Signature, payload string, k *GPGKey, committer, signer *User, email string) *CommitVerification {
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key, err := hashAndVerifyWithSubKeys(sig, payload, k)
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if err != nil { // Skipping failed to generate hash
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return &CommitVerification{
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CommittingUser: committer,
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Verified: false,
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Reason: "gpg.error.generate_hash",
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}
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}
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if key != nil {
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return &CommitVerification{ // Everything is ok
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CommittingUser: committer,
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Verified: true,
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Reason: fmt.Sprintf("%s / %s", signer.Name, key.KeyID),
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SigningUser: signer,
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SigningKey: key,
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SigningEmail: email,
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}
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}
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return nil
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}
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func hashAndVerifyForKeyID(sig *packet.Signature, payload string, committer *User, keyID, name, email string) *CommitVerification {
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if keyID == "" {
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return nil
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}
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keys, err := GetGPGKeysByKeyID(keyID)
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if err != nil {
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log.Error("GetGPGKeysByKeyID: %v", err)
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return &CommitVerification{
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CommittingUser: committer,
|
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Verified: false,
|
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Reason: "gpg.error.failed_retrieval_gpg_keys",
|
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}
|
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}
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if len(keys) == 0 {
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return nil
|
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}
|
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for _, key := range keys {
|
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var primaryKeys []*GPGKey
|
||||
if key.PrimaryKeyID != "" {
|
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primaryKeys, err = GetGPGKeysByKeyID(key.PrimaryKeyID)
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if err != nil {
|
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log.Error("GetGPGKeysByKeyID: %v", err)
|
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return &CommitVerification{
|
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CommittingUser: committer,
|
||||
Verified: false,
|
||||
Reason: "gpg.error.failed_retrieval_gpg_keys",
|
||||
}
|
||||
}
|
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}
|
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|
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activated, email := checkKeyEmails(email, append([]*GPGKey{key}, primaryKeys...)...)
|
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if !activated {
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continue
|
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}
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|
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signer := &User{
|
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Name: name,
|
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Email: email,
|
||||
}
|
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if key.OwnerID != 0 {
|
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owner, err := GetUserByID(key.OwnerID)
|
||||
if err == nil {
|
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signer = owner
|
||||
} else if !IsErrUserNotExist(err) {
|
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log.Error("Failed to GetUserByID: %d for key ID: %d (%s) %v", key.OwnerID, key.ID, key.KeyID, err)
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return &CommitVerification{
|
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CommittingUser: committer,
|
||||
Verified: false,
|
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Reason: "gpg.error.no_committer_account",
|
||||
}
|
||||
}
|
||||
}
|
||||
commitVerification := hashAndVerifyWithSubKeysCommitVerification(sig, payload, key, committer, signer, email)
|
||||
if commitVerification != nil {
|
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return commitVerification
|
||||
}
|
||||
}
|
||||
// This is a bad situation ... We have a key id that is in our database but the signature doesn't match.
|
||||
return &CommitVerification{
|
||||
CommittingUser: committer,
|
||||
Verified: false,
|
||||
Warning: true,
|
||||
Reason: BadSignature,
|
||||
}
|
||||
}
|
||||
|
||||
// CalculateTrustStatus will calculate the TrustStatus for a commit verification within a repository
|
||||
func CalculateTrustStatus(verification *CommitVerification, repository *Repository, keyMap *map[string]bool) (err error) {
|
||||
if !verification.Verified {
|
||||
return
|
||||
}
|
||||
|
||||
// There are several trust models in Gitea
|
||||
trustModel := repository.GetTrustModel()
|
||||
|
||||
// In the Committer trust model a signature is trusted if it matches the committer
|
||||
// - it doesn't matter if they're a collaborator, the owner, Gitea or Github
|
||||
// NB: This model is commit verification only
|
||||
if trustModel == CommitterTrustModel {
|
||||
// default to "unmatched"
|
||||
verification.TrustStatus = "unmatched"
|
||||
|
||||
// We can only verify against users in our database but the default key will match
|
||||
// against by email if it is not in the db.
|
||||
if (verification.SigningUser.ID != 0 &&
|
||||
verification.CommittingUser.ID == verification.SigningUser.ID) ||
|
||||
(verification.SigningUser.ID == 0 && verification.CommittingUser.ID == 0 &&
|
||||
verification.SigningUser.Email == verification.CommittingUser.Email) {
|
||||
verification.TrustStatus = "trusted"
|
||||
}
|
||||
return
|
||||
}
|
||||
|
||||
// Now we drop to the more nuanced trust models...
|
||||
verification.TrustStatus = "trusted"
|
||||
|
||||
if verification.SigningUser.ID == 0 {
|
||||
// This commit is signed by the default key - but this key is not assigned to a user in the DB.
|
||||
|
||||
// However in the CollaboratorCommitterTrustModel we cannot mark this as trusted
|
||||
// unless the default key matches the email of a non-user.
|
||||
if trustModel == CollaboratorCommitterTrustModel && (verification.CommittingUser.ID != 0 ||
|
||||
verification.SigningUser.Email != verification.CommittingUser.Email) {
|
||||
verification.TrustStatus = "untrusted"
|
||||
}
|
||||
return
|
||||
}
|
||||
|
||||
var isMember bool
|
||||
if keyMap != nil {
|
||||
var has bool
|
||||
isMember, has = (*keyMap)[verification.SigningKey.KeyID]
|
||||
if !has {
|
||||
isMember, err = repository.IsOwnerMemberCollaborator(verification.SigningUser.ID)
|
||||
(*keyMap)[verification.SigningKey.KeyID] = isMember
|
||||
}
|
||||
} else {
|
||||
isMember, err = repository.IsOwnerMemberCollaborator(verification.SigningUser.ID)
|
||||
}
|
||||
|
||||
if !isMember {
|
||||
verification.TrustStatus = "untrusted"
|
||||
if verification.CommittingUser.ID != verification.SigningUser.ID {
|
||||
// The committing user and the signing user are not the same
|
||||
// This should be marked as questionable unless the signing user is a collaborator/team member etc.
|
||||
verification.TrustStatus = "unmatched"
|
||||
}
|
||||
} else if trustModel == CollaboratorCommitterTrustModel && verification.CommittingUser.ID != verification.SigningUser.ID {
|
||||
// The committing user and the signing user are not the same and our trustmodel states that they must match
|
||||
verification.TrustStatus = "unmatched"
|
||||
}
|
||||
|
||||
return
|
||||
}
|
||||
Reference in New Issue
Block a user