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models/asymkey: Implement Tag verification

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This is, in large part, a refactoring: we rename `CommitVerification` to
`ObjectVerification`, and adjust `ParseObjectWithSignature` (previously
`ParseCommitWithSignature`) to work on an object, rather than a commit.

This in turn, lets us implement `ParseTagWithSignature` on top of it, so
commit & tag signature verification will share most of the code.

Work sponsored by @glts.

Signed-off-by: Gergely Nagy <forgejo@gergo.csillger.hu>
This commit is contained in:
Gergely Nagy 2024-03-04 19:11:42 +01:00 committed by GitHub
parent 923035e418
commit 4dd475dfe5
6 changed files with 568 additions and 501 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

492
models/asymkey/gpg_key_commit_verification.go
View file

@ -5,18 +5,10 @@ package asymkey
import (
"context"
"fmt"
"hash"
"strings"
"code.gitea.io/gitea/models/db"
repo_model "code.gitea.io/gitea/models/repo"
user_model "code.gitea.io/gitea/models/user"
"code.gitea.io/gitea/modules/git"
"code.gitea.io/gitea/modules/log"
"code.gitea.io/gitea/modules/setting"
"github.com/keybase/go-crypto/openpgp/packet"
)
// __________________ ________ ____ __.
@ -40,45 +32,22 @@ import (
// This file provides functions relating commit verification
// CommitVerification represents a commit validation of signature
type CommitVerification struct {
Verified bool
Warning bool
Reason string
SigningUser *user_model.User
CommittingUser *user_model.User
SigningEmail string
SigningKey *GPGKey
SigningSSHKey *PublicKey
TrustStatus string
}
// SignCommit represents a commit with validation of signature.
type SignCommit struct {
Verification *CommitVerification
Verification *ObjectVerification
*user_model.UserCommit
}
const (
// BadSignature is used as the reason when the signature has a KeyID that is in the db
// but no key that has that ID verifies the signature. This is a suspicious failure.
BadSignature = "gpg.error.probable_bad_signature"
// BadDefaultSignature is used as the reason when the signature has a KeyID that matches the
// default Key but is not verified by the default key. This is a suspicious failure.
BadDefaultSignature = "gpg.error.probable_bad_default_signature"
// NoKeyFound is used as the reason when no key can be found to verify the signature.
NoKeyFound = "gpg.error.no_gpg_keys_found"
)
// ParseCommitsWithSignature checks if signaute of commits are corresponding to users gpg keys.
func ParseCommitsWithSignature(ctx context.Context, oldCommits []*user_model.UserCommit, repoTrustModel repo_model.TrustModelType, isOwnerMemberCollaborator func(*user_model.User) (bool, error)) []*SignCommit {
newCommits := make([]*SignCommit, 0, len(oldCommits))
keyMap := map[string]bool{}
for _, c := range oldCommits {
o := commitToGitObject(c.Commit)
signCommit := &SignCommit{
UserCommit: c,
Verification: ParseCommitWithSignature(ctx, c.Commit),
Verification: ParseObjectWithSignature(ctx, &o),
}
_ = CalculateTrustStatus(signCommit.Verification, repoTrustModel, isOwnerMemberCollaborator, &keyMap)
@ -88,456 +57,7 @@ func ParseCommitsWithSignature(ctx context.Context, oldCommits []*user_model.Use
return newCommits
}
// ParseCommitWithSignature check if signature is good against keystore.
func ParseCommitWithSignature(ctx context.Context, c *git.Commit) *CommitVerification {
var committer *user_model.User
if c.Committer != nil {
var err error
// Find Committer account
committer, err = user_model.GetUserByEmail(ctx, c.Committer.Email) // This finds the user by primary email or activated email so commit will not be valid if email is not
if err != nil { // Skipping not user for committer
committer = &user_model.User{
Name: c.Committer.Name,
Email: c.Committer.Email,
}
// We can expect this to often be an ErrUserNotExist. in the case
// it is not, however, it is important to log it.
if !user_model.IsErrUserNotExist(err) {
log.Error("GetUserByEmail: %v", err)
return &CommitVerification{
CommittingUser: committer,
Verified: false,
Reason: "gpg.error.no_committer_account",
}
}
}
}
// If no signature just report the committer
if c.Signature == nil {
return &CommitVerification{
CommittingUser: committer,
Verified: false, // Default value
Reason: "gpg.error.not_signed_commit", // Default value
}
}
// If this a SSH signature handle it differently
if strings.HasPrefix(c.Signature.Signature, "-----BEGIN SSH SIGNATURE-----") {
return ParseCommitWithSSHSignature(ctx, c, committer)
}
// Parsing signature
sig, err := extractSignature(c.Signature.Signature)
if err != nil { // Skipping failed to extract sign
log.Error("SignatureRead err: %v", err)
return &CommitVerification{
CommittingUser: committer,
Verified: false,
Reason: "gpg.error.extract_sign",
}
}
keyID := ""
if sig.IssuerKeyId != nil && (*sig.IssuerKeyId) != 0 {
keyID = fmt.Sprintf("%X", *sig.IssuerKeyId)
}
if keyID == "" && sig.IssuerFingerprint != nil && len(sig.IssuerFingerprint) > 0 {
keyID = fmt.Sprintf("%X", sig.IssuerFingerprint[12:20])
}
defaultReason := NoKeyFound
// First check if the sig has a keyID and if so just look at that
if commitVerification := hashAndVerifyForKeyID(
ctx,
sig,
c.Signature.Payload,
committer,
keyID,
setting.AppName,
""); commitVerification != nil {
if commitVerification.Reason == BadSignature {
defaultReason = BadSignature
} else {
return commitVerification
}
}
// Now try to associate the signature with the committer, if present
if committer.ID != 0 {
keys, err := db.Find[GPGKey](ctx, FindGPGKeyOptions{
OwnerID: committer.ID,
})
if err != nil { // Skipping failed to get gpg keys of user
log.Error("ListGPGKeys: %v", err)
return &CommitVerification{
CommittingUser: committer,
Verified: false,
Reason: "gpg.error.failed_retrieval_gpg_keys",
}
}
if err := GPGKeyList(keys).LoadSubKeys(ctx); err != nil {
log.Error("LoadSubKeys: %v", err)
return &CommitVerification{
CommittingUser: committer,
Verified: false,
Reason: "gpg.error.failed_retrieval_gpg_keys",
}
}
committerEmailAddresses, _ := user_model.GetEmailAddresses(ctx, committer.ID)
activated := false
for _, e := range committerEmailAddresses {
if e.IsActivated && strings.EqualFold(e.Email, c.Committer.Email) {
activated = true
break
}
}
for _, k := range keys {
// Pre-check (& optimization) that emails attached to key can be attached to the committer email and can validate
canValidate := false
email := ""
if k.Verified && activated {
canValidate = true
email = c.Committer.Email
}
if !canValidate {
for _, e := range k.Emails {
if e.IsActivated && strings.EqualFold(e.Email, c.Committer.Email) {
canValidate = true
email = e.Email
break
}
}
}
if !canValidate {
continue // Skip this key
}
commitVerification := hashAndVerifyWithSubKeysCommitVerification(sig, c.Signature.Payload, k, committer, committer, email)
if commitVerification != nil {
return commitVerification
}
}
}
if setting.Repository.Signing.SigningKey != "" && setting.Repository.Signing.SigningKey != "default" && setting.Repository.Signing.SigningKey != "none" {
// OK we should try the default key
gpgSettings := git.GPGSettings{
Sign: true,
KeyID: setting.Repository.Signing.SigningKey,
Name: setting.Repository.Signing.SigningName,
Email: setting.Repository.Signing.SigningEmail,
}
if err := gpgSettings.LoadPublicKeyContent(); err != nil {
log.Error("Error getting default signing key: %s %v", gpgSettings.KeyID, err)
} else if commitVerification := verifyWithGPGSettings(ctx, &gpgSettings, sig, c.Signature.Payload, committer, keyID); commitVerification != nil {
if commitVerification.Reason == BadSignature {
defaultReason = BadSignature
} else {
return commitVerification
}
}
}
defaultGPGSettings, err := c.GetRepositoryDefaultPublicGPGKey(false)
if err != nil {
log.Error("Error getting default public gpg key: %v", err)
} else if defaultGPGSettings == nil {
log.Warn("Unable to get defaultGPGSettings for unattached commit: %s", c.ID.String())
} else if defaultGPGSettings.Sign {
if commitVerification := verifyWithGPGSettings(ctx, defaultGPGSettings, sig, c.Signature.Payload, committer, keyID); commitVerification != nil {
if commitVerification.Reason == BadSignature {
defaultReason = BadSignature
} else {
return commitVerification
}
}
}
return &CommitVerification{ // Default at this stage
CommittingUser: committer,
Verified: false,
Warning: defaultReason != NoKeyFound,
Reason: defaultReason,
SigningKey: &GPGKey{
KeyID: keyID,
},
}
}
func verifyWithGPGSettings(ctx context.Context, gpgSettings *git.GPGSettings, sig *packet.Signature, payload string, committer *user_model.User, keyID string) *CommitVerification {
// First try to find the key in the db
if commitVerification := hashAndVerifyForKeyID(ctx, sig, payload, committer, gpgSettings.KeyID, gpgSettings.Name, gpgSettings.Email); commitVerification != nil {
return commitVerification
}
// Otherwise we have to parse the key
ekeys, err := checkArmoredGPGKeyString(gpgSettings.PublicKeyContent)
if err != nil {
log.Error("Unable to get default signing key: %v", err)
return &CommitVerification{
CommittingUser: committer,
Verified: false,
Reason: "gpg.error.generate_hash",
}
}
for _, ekey := range ekeys {
pubkey := ekey.PrimaryKey
content, err := base64EncPubKey(pubkey)
if err != nil {
return &CommitVerification{
CommittingUser: committer,
Verified: false,
Reason: "gpg.error.generate_hash",
}
}
k := &GPGKey{
Content: content,
CanSign: pubkey.CanSign(),
KeyID: pubkey.KeyIdString(),
}
for _, subKey := range ekey.Subkeys {
content, err := base64EncPubKey(subKey.PublicKey)
if err != nil {
return &CommitVerification{
CommittingUser: committer,
Verified: false,
Reason: "gpg.error.generate_hash",
}
}
k.SubsKey = append(k.SubsKey, &GPGKey{
Content: content,
CanSign: subKey.PublicKey.CanSign(),
KeyID: subKey.PublicKey.KeyIdString(),
})
}
if commitVerification := hashAndVerifyWithSubKeysCommitVerification(sig, payload, k, committer, &user_model.User{
Name: gpgSettings.Name,
Email: gpgSettings.Email,
}, gpgSettings.Email); commitVerification != nil {
return commitVerification
}
if keyID == k.KeyID {
// This is a bad situation ... We have a key id that matches our default key but the signature doesn't match.
return &CommitVerification{
CommittingUser: committer,
Verified: false,
Warning: true,
Reason: BadSignature,
}
}
}
return nil
}
func verifySign(s *packet.Signature, h hash.Hash, k *GPGKey) error {
// Check if key can sign
if !k.CanSign {
return fmt.Errorf("key can not sign")
}
// Decode key
pkey, err := base64DecPubKey(k.Content)
if err != nil {
return err
}
return pkey.VerifySignature(h, s)
}
func hashAndVerify(sig *packet.Signature, payload string, k *GPGKey) (*GPGKey, error) {
// Generating hash of commit
hash, err := populateHash(sig.Hash, []byte(payload))
if err != nil { // Skipping as failed to generate hash
log.Error("PopulateHash: %v", err)
return nil, err
}
// We will ignore errors in verification as they don't need to be propagated up
err = verifySign(sig, hash, k)
if err != nil {
return nil, nil
}
return k, nil
}
func hashAndVerifyWithSubKeys(sig *packet.Signature, payload string, k *GPGKey) (*GPGKey, error) {
verified, err := hashAndVerify(sig, payload, k)
if err != nil || verified != nil {
return verified, err
}
for _, sk := range k.SubsKey {
verified, err := hashAndVerify(sig, payload, sk)
if err != nil || verified != nil {
return verified, err
}
}
return nil, nil
}
func hashAndVerifyWithSubKeysCommitVerification(sig *packet.Signature, payload string, k *GPGKey, committer, signer *user_model.User, email string) *CommitVerification {
key, err := hashAndVerifyWithSubKeys(sig, payload, k)
if err != nil { // Skipping failed to generate hash
return &CommitVerification{
CommittingUser: committer,
Verified: false,
Reason: "gpg.error.generate_hash",
}
}
if key != nil {
return &CommitVerification{ // Everything is ok
CommittingUser: committer,
Verified: true,
Reason: fmt.Sprintf("%s / %s", signer.Name, key.KeyID),
SigningUser: signer,
SigningKey: key,
SigningEmail: email,
}
}
return nil
}
func hashAndVerifyForKeyID(ctx context.Context, sig *packet.Signature, payload string, committer *user_model.User, keyID, name, email string) *CommitVerification {
if keyID == "" {
return nil
}
keys, err := db.Find[GPGKey](ctx, FindGPGKeyOptions{
KeyID: keyID,
IncludeSubKeys: true,
})
if err != nil {
log.Error("GetGPGKeysByKeyID: %v", err)
return &CommitVerification{
CommittingUser: committer,
Verified: false,
Reason: "gpg.error.failed_retrieval_gpg_keys",
}
}
if len(keys) == 0 {
return nil
}
for _, key := range keys {
var primaryKeys []*GPGKey
if key.PrimaryKeyID != "" {
primaryKeys, err = db.Find[GPGKey](ctx, FindGPGKeyOptions{
KeyID: key.PrimaryKeyID,
IncludeSubKeys: true,
})
if err != nil {
log.Error("GetGPGKeysByKeyID: %v", err)
return &CommitVerification{
CommittingUser: committer,
Verified: false,
Reason: "gpg.error.failed_retrieval_gpg_keys",
}
}
}
activated, email := checkKeyEmails(ctx, email, append([]*GPGKey{key}, primaryKeys...)...)
if !activated {
continue
}
signer := &user_model.User{
Name: name,
Email: email,
}
if key.OwnerID != 0 {
owner, err := user_model.GetUserByID(ctx, key.OwnerID)
if err == nil {
signer = owner
} else if !user_model.IsErrUserNotExist(err) {
log.Error("Failed to user_model.GetUserByID: %d for key ID: %d (%s) %v", key.OwnerID, key.ID, key.KeyID, err)
return &CommitVerification{
CommittingUser: committer,
Verified: false,
Reason: "gpg.error.no_committer_account",
}
}
}
commitVerification := hashAndVerifyWithSubKeysCommitVerification(sig, payload, key, committer, signer, email)
if commitVerification != nil {
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
// There are several trust models in Gitea
func CalculateTrustStatus(verification *CommitVerification, repoTrustModel repo_model.TrustModelType, isOwnerMemberCollaborator func(*user_model.User) (bool, error), keyMap *map[string]bool) error {
if !verification.Verified {
return nil
}
// 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 repoTrustModel == repo_model.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 nil
}
// 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 repo_model.CollaboratorCommitterTrustModel we cannot mark this as trusted
// unless the default key matches the email of a non-user.
if repoTrustModel == repo_model.CollaboratorCommitterTrustModel && (verification.CommittingUser.ID != 0 ||
verification.SigningUser.Email != verification.CommittingUser.Email) {
verification.TrustStatus = "untrusted"
}
return nil
}
// Check we actually have a GPG SigningKey
var err error
if verification.SigningKey != nil {
var isMember bool
if keyMap != nil {
var has bool
isMember, has = (*keyMap)[verification.SigningKey.KeyID]
if !has {
isMember, err = isOwnerMemberCollaborator(verification.SigningUser)
(*keyMap)[verification.SigningKey.KeyID] = isMember
}
} else {
isMember, err = isOwnerMemberCollaborator(verification.SigningUser)
}
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 repoTrustModel == repo_model.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 err
func ParseCommitWithSignature(ctx context.Context, c *git.Commit) *ObjectVerification {
o := commitToGitObject(c)
return ParseObjectWithSignature(ctx, &o)
}

527
models/asymkey/gpg_key_object_verification.go Normal file
View file

@ -0,0 +1,527 @@
// Copyright 2021 The Gitea Authors. All rights reserved.
// Copyright 2024 The Forgejo Authors c/o Codeberg e.V.. All rights reserved.
// SPDX-License-Identifier: MIT
package asymkey
import (
"context"
"fmt"
"hash"
"strings"
"code.gitea.io/gitea/models/db"
repo_model "code.gitea.io/gitea/models/repo"
user_model "code.gitea.io/gitea/models/user"
"code.gitea.io/gitea/modules/git"
"code.gitea.io/gitea/modules/log"
"code.gitea.io/gitea/modules/setting"
"github.com/keybase/go-crypto/openpgp/packet"
)
// This file provides functions related to object (commit, tag) verification
// ObjectVerification represents a commit validation of signature
type ObjectVerification struct {
Verified bool
Warning bool
Reason string
SigningUser *user_model.User
CommittingUser *user_model.User
SigningEmail string
SigningKey *GPGKey
SigningSSHKey *PublicKey
TrustStatus string
}
const (
// BadSignature is used as the reason when the signature has a KeyID that is in the db
// but no key that has that ID verifies the signature. This is a suspicious failure.
BadSignature = "gpg.error.probable_bad_signature"
// BadDefaultSignature is used as the reason when the signature has a KeyID that matches the
// default Key but is not verified by the default key. This is a suspicious failure.
BadDefaultSignature = "gpg.error.probable_bad_default_signature"
// NoKeyFound is used as the reason when no key can be found to verify the signature.
NoKeyFound = "gpg.error.no_gpg_keys_found"
)
type GitObject struct {
ID git.ObjectID
Committer *git.Signature
Signature *git.ObjectSignature
Commit *git.Commit
}
func commitToGitObject(c *git.Commit) GitObject {
return GitObject{
ID: c.ID,
Committer: c.Committer,
Signature: c.Signature,
Commit: c,
}
}
func tagToGitObject(t *git.Tag, gitRepo *git.Repository) GitObject {
commit, _ := t.Commit(gitRepo)
return GitObject{
ID: t.ID,
Committer: t.Tagger,
Signature: t.Signature,
Commit: commit,
}
}
// ParseObjectWithSignature check if signature is good against keystore.
func ParseObjectWithSignature(ctx context.Context, c *GitObject) *ObjectVerification {
var committer *user_model.User
if c.Committer != nil {
var err error
// Find Committer account
committer, err = user_model.GetUserByEmail(ctx, c.Committer.Email) // This finds the user by primary email or activated email so commit will not be valid if email is not
if err != nil { // Skipping not user for committer
committer = &user_model.User{
Name: c.Committer.Name,
Email: c.Committer.Email,
}
// We can expect this to often be an ErrUserNotExist. in the case
// it is not, however, it is important to log it.
if !user_model.IsErrUserNotExist(err) {
log.Error("GetUserByEmail: %v", err)
return &ObjectVerification{
CommittingUser: committer,
Verified: false,
Reason: "gpg.error.no_committer_account",
}
}
}
}
// If no signature just report the committer
if c.Signature == nil {
return &ObjectVerification{
CommittingUser: committer,
Verified: false, // Default value
Reason: "gpg.error.not_signed_commit", // Default value
}
}
// If this a SSH signature handle it differently
if strings.HasPrefix(c.Signature.Signature, "-----BEGIN SSH SIGNATURE-----") {
return ParseObjectWithSSHSignature(ctx, c, committer)
}
// Parsing signature
sig, err := extractSignature(c.Signature.Signature)
if err != nil { // Skipping failed to extract sign
log.Error("SignatureRead err: %v", err)
return &ObjectVerification{
CommittingUser: committer,
Verified: false,
Reason: "gpg.error.extract_sign",
}
}
keyID := ""
if sig.IssuerKeyId != nil && (*sig.IssuerKeyId) != 0 {
keyID = fmt.Sprintf("%X", *sig.IssuerKeyId)
}
if keyID == "" && sig.IssuerFingerprint != nil && len(sig.IssuerFingerprint) > 0 {
keyID = fmt.Sprintf("%X", sig.IssuerFingerprint[12:20])
}
defaultReason := NoKeyFound
// First check if the sig has a keyID and if so just look at that
if commitVerification := hashAndVerifyForKeyID(
ctx,
sig,
c.Signature.Payload,
committer,
keyID,
setting.AppName,
""); commitVerification != nil {
if commitVerification.Reason == BadSignature {
defaultReason = BadSignature
} else {
return commitVerification
}
}
// Now try to associate the signature with the committer, if present
if committer.ID != 0 {
keys, err := db.Find[GPGKey](ctx, FindGPGKeyOptions{
OwnerID: committer.ID,
})
if err != nil { // Skipping failed to get gpg keys of user
log.Error("ListGPGKeys: %v", err)
return &ObjectVerification{
CommittingUser: committer,
Verified: false,
Reason: "gpg.error.failed_retrieval_gpg_keys",
}
}
if err := GPGKeyList(keys).LoadSubKeys(ctx); err != nil {
log.Error("LoadSubKeys: %v", err)
return &ObjectVerification{
CommittingUser: committer,
Verified: false,
Reason: "gpg.error.failed_retrieval_gpg_keys",
}
}
committerEmailAddresses, _ := user_model.GetEmailAddresses(ctx, committer.ID)
activated := false
for _, e := range committerEmailAddresses {
if e.IsActivated && strings.EqualFold(e.Email, c.Committer.Email) {
activated = true
break
}
}
for _, k := range keys {
// Pre-check (& optimization) that emails attached to key can be attached to the committer email and can validate
canValidate := false
email := ""
if k.Verified && activated {
canValidate = true
email = c.Committer.Email
}
if !canValidate {
for _, e := range k.Emails {
if e.IsActivated && strings.EqualFold(e.Email, c.Committer.Email) {
canValidate = true
email = e.Email
break
}
}
}
if !canValidate {
continue // Skip this key
}
commitVerification := hashAndVerifyWithSubKeysObjectVerification(sig, c.Signature.Payload, k, committer, committer, email)
if commitVerification != nil {
return commitVerification
}
}
}
if setting.Repository.Signing.SigningKey != "" && setting.Repository.Signing.SigningKey != "default" && setting.Repository.Signing.SigningKey != "none" {
// OK we should try the default key
gpgSettings := git.GPGSettings{
Sign: true,
KeyID: setting.Repository.Signing.SigningKey,
Name: setting.Repository.Signing.SigningName,
Email: setting.Repository.Signing.SigningEmail,
}
if err := gpgSettings.LoadPublicKeyContent(); err != nil {
log.Error("Error getting default signing key: %s %v", gpgSettings.KeyID, err)
} else if commitVerification := verifyWithGPGSettings(ctx, &gpgSettings, sig, c.Signature.Payload, committer, keyID); commitVerification != nil {
if commitVerification.Reason == BadSignature {
defaultReason = BadSignature
} else {
return commitVerification
}
}
}
defaultGPGSettings, err := c.Commit.GetRepositoryDefaultPublicGPGKey(false)
if err != nil {
log.Error("Error getting default public gpg key: %v", err)
} else if defaultGPGSettings == nil {
log.Warn("Unable to get defaultGPGSettings for unattached commit: %s", c.Commit.ID.String())
} else if defaultGPGSettings.Sign {
if commitVerification := verifyWithGPGSettings(ctx, defaultGPGSettings, sig, c.Signature.Payload, committer, keyID); commitVerification != nil {
if commitVerification.Reason == BadSignature {
defaultReason = BadSignature
} else {
return commitVerification
}
}
}
return &ObjectVerification{ // Default at this stage
CommittingUser: committer,
Verified: false,
Warning: defaultReason != NoKeyFound,
Reason: defaultReason,
SigningKey: &GPGKey{
KeyID: keyID,
},
}
}
func verifyWithGPGSettings(ctx context.Context, gpgSettings *git.GPGSettings, sig *packet.Signature, payload string, committer *user_model.User, keyID string) *ObjectVerification {
// First try to find the key in the db
if commitVerification := hashAndVerifyForKeyID(ctx, sig, payload, committer, gpgSettings.KeyID, gpgSettings.Name, gpgSettings.Email); commitVerification != nil {
return commitVerification
}
// Otherwise we have to parse the key
ekeys, err := checkArmoredGPGKeyString(gpgSettings.PublicKeyContent)
if err != nil {
log.Error("Unable to get default signing key: %v", err)
return &ObjectVerification{
CommittingUser: committer,
Verified: false,
Reason: "gpg.error.generate_hash",
}
}
for _, ekey := range ekeys {
pubkey := ekey.PrimaryKey
content, err := base64EncPubKey(pubkey)
if err != nil {
return &ObjectVerification{
CommittingUser: committer,
Verified: false,
Reason: "gpg.error.generate_hash",
}
}
k := &GPGKey{
Content: content,
CanSign: pubkey.CanSign(),
KeyID: pubkey.KeyIdString(),
}
for _, subKey := range ekey.Subkeys {
content, err := base64EncPubKey(subKey.PublicKey)
if err != nil {
return &ObjectVerification{
CommittingUser: committer,
Verified: false,
Reason: "gpg.error.generate_hash",
}
}
k.SubsKey = append(k.SubsKey, &GPGKey{
Content: content,
CanSign: subKey.PublicKey.CanSign(),
KeyID: subKey.PublicKey.KeyIdString(),
})
}
if commitVerification := hashAndVerifyWithSubKeysObjectVerification(sig, payload, k, committer, &user_model.User{
Name: gpgSettings.Name,
Email: gpgSettings.Email,
}, gpgSettings.Email); commitVerification != nil {
return commitVerification
}
if keyID == k.KeyID {
// This is a bad situation ... We have a key id that matches our default key but the signature doesn't match.
return &ObjectVerification{
CommittingUser: committer,
Verified: false,
Warning: true,
Reason: BadSignature,
}
}
}
return nil
}
func verifySign(s *packet.Signature, h hash.Hash, k *GPGKey) error {
// Check if key can sign
if !k.CanSign {
return fmt.Errorf("key can not sign")
}
// Decode key
pkey, err := base64DecPubKey(k.Content)
if err != nil {
return err
}
return pkey.VerifySignature(h, s)
}
func hashAndVerify(sig *packet.Signature, payload string, k *GPGKey) (*GPGKey, error) {
// Generating hash of commit
hash, err := populateHash(sig.Hash, []byte(payload))
if err != nil { // Skipping as failed to generate hash
log.Error("PopulateHash: %v", err)
return nil, err
}
// We will ignore errors in verification as they don't need to be propagated up
err = verifySign(sig, hash, k)
if err != nil {
return nil, nil
}
return k, nil
}
func hashAndVerifyWithSubKeys(sig *packet.Signature, payload string, k *GPGKey) (*GPGKey, error) {
verified, err := hashAndVerify(sig, payload, k)
if err != nil || verified != nil {
return verified, err
}
for _, sk := range k.SubsKey {
verified, err := hashAndVerify(sig, payload, sk)
if err != nil || verified != nil {
return verified, err
}
}
return nil, nil
}
func hashAndVerifyWithSubKeysObjectVerification(sig *packet.Signature, payload string, k *GPGKey, committer, signer *user_model.User, email string) *ObjectVerification {
key, err := hashAndVerifyWithSubKeys(sig, payload, k)
if err != nil { // Skipping failed to generate hash
return &ObjectVerification{
CommittingUser: committer,
Verified: false,
Reason: "gpg.error.generate_hash",
}
}
if key != nil {
return &ObjectVerification{ // Everything is ok
CommittingUser: committer,
Verified: true,
Reason: fmt.Sprintf("%s / %s", signer.Name, key.KeyID),
SigningUser: signer,
SigningKey: key,
SigningEmail: email,
}
}
return nil
}
func hashAndVerifyForKeyID(ctx context.Context, sig *packet.Signature, payload string, committer *user_model.User, keyID, name, email string) *ObjectVerification {
if keyID == "" {
return nil
}
keys, err := db.Find[GPGKey](ctx, FindGPGKeyOptions{
KeyID: keyID,
IncludeSubKeys: true,
})
if err != nil {
log.Error("GetGPGKeysByKeyID: %v", err)
return &ObjectVerification{
CommittingUser: committer,
Verified: false,
Reason: "gpg.error.failed_retrieval_gpg_keys",
}
}
if len(keys) == 0 {
return nil
}
for _, key := range keys {
var primaryKeys []*GPGKey
if key.PrimaryKeyID != "" {
primaryKeys, err = db.Find[GPGKey](ctx, FindGPGKeyOptions{
KeyID: key.PrimaryKeyID,
IncludeSubKeys: true,
})
if err != nil {
log.Error("GetGPGKeysByKeyID: %v", err)
return &ObjectVerification{
CommittingUser: committer,
Verified: false,
Reason: "gpg.error.failed_retrieval_gpg_keys",
}
}
}
activated, email := checkKeyEmails(ctx, email, append([]*GPGKey{key}, primaryKeys...)...)
if !activated {
continue
}
signer := &user_model.User{
Name: name,
Email: email,
}
if key.OwnerID != 0 {
owner, err := user_model.GetUserByID(ctx, key.OwnerID)
if err == nil {
signer = owner
} else if !user_model.IsErrUserNotExist(err) {
log.Error("Failed to user_model.GetUserByID: %d for key ID: %d (%s) %v", key.OwnerID, key.ID, key.KeyID, err)
return &ObjectVerification{
CommittingUser: committer,
Verified: false,
Reason: "gpg.error.no_committer_account",
}
}
}
commitVerification := hashAndVerifyWithSubKeysObjectVerification(sig, payload, key, committer, signer, email)
if commitVerification != nil {
return commitVerification
}
}
// This is a bad situation ... We have a key id that is in our database but the signature doesn't match.
return &ObjectVerification{
CommittingUser: committer,
Verified: false,
Warning: true,
Reason: BadSignature,
}
}
// CalculateTrustStatus will calculate the TrustStatus for a commit verification within a repository
// There are several trust models in Gitea
func CalculateTrustStatus(verification *ObjectVerification, repoTrustModel repo_model.TrustModelType, isOwnerMemberCollaborator func(*user_model.User) (bool, error), keyMap *map[string]bool) error {
if !verification.Verified {
return nil
}
// 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 repoTrustModel == repo_model.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 nil
}
// 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 repo_model.CollaboratorCommitterTrustModel we cannot mark this as trusted
// unless the default key matches the email of a non-user.
if repoTrustModel == repo_model.CollaboratorCommitterTrustModel && (verification.CommittingUser.ID != 0 ||
verification.SigningUser.Email != verification.CommittingUser.Email) {
verification.TrustStatus = "untrusted"
}
return nil
}
// Check we actually have a GPG SigningKey
var err error
if verification.SigningKey != nil {
var isMember bool
if keyMap != nil {
var has bool
isMember, has = (*keyMap)[verification.SigningKey.KeyID]
if !has {
isMember, err = isOwnerMemberCollaborator(verification.SigningUser)
(*keyMap)[verification.SigningKey.KeyID] = isMember
}
} else {
isMember, err = isOwnerMemberCollaborator(verification.SigningUser)
}
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 repoTrustModel == repo_model.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 err
}

15
models/asymkey/gpg_key_tag_verification.go Normal file
View file

@ -0,0 +1,15 @@
// Copyright 2024 The Forgejo Authors c/o Codeberg e.V.. All rights reserved.
// SPDX-License-Identifier: MIT
package asymkey
import (
"context"
"code.gitea.io/gitea/modules/git"
)
func ParseTagWithSignature(ctx context.Context, gitRepo *git.Repository, t *git.Tag) *ObjectVerification {
o := tagToGitObject(t, gitRepo)
return ParseObjectWithSignature(ctx, &o)
}

15
models/asymkey/ssh_key_commit_verification.go → models/asymkey/ssh_key_object_verification.go
View file

@ -11,14 +11,13 @@ import (
"code.gitea.io/gitea/models/db"
user_model "code.gitea.io/gitea/models/user"
"code.gitea.io/gitea/modules/git"
"code.gitea.io/gitea/modules/log"
"github.com/42wim/sshsig"
)
// ParseCommitWithSSHSignature check if signature is good against keystore.
func ParseCommitWithSSHSignature(ctx context.Context, c *git.Commit, committer *user_model.User) *CommitVerification {
// ParseObjectWithSSHSignature check if signature is good against keystore.
func ParseObjectWithSSHSignature(ctx context.Context, c *GitObject, committer *user_model.User) *ObjectVerification {
// Now try to associate the signature with the committer, if present
if committer.ID != 0 {
keys, err := db.Find[PublicKey](ctx, FindPublicKeyOptions{
@ -27,7 +26,7 @@ func ParseCommitWithSSHSignature(ctx context.Context, c *git.Commit, committer *
})
if err != nil { // Skipping failed to get ssh keys of user
log.Error("ListPublicKeys: %v", err)
return &CommitVerification{
return &ObjectVerification{
CommittingUser: committer,
Verified: false,
Reason: "gpg.error.failed_retrieval_gpg_keys",
@ -55,7 +54,7 @@ func ParseCommitWithSSHSignature(ctx context.Context, c *git.Commit, committer *
for _, k := range keys {
if k.Verified && activated {
commitVerification := verifySSHCommitVerification(c.Signature.Signature, c.Signature.Payload, k, committer, committer, c.Committer.Email)
commitVerification := verifySSHObjectVerification(c.Signature.Signature, c.Signature.Payload, k, committer, committer, c.Committer.Email)
if commitVerification != nil {
return commitVerification
}
@ -63,19 +62,19 @@ func ParseCommitWithSSHSignature(ctx context.Context, c *git.Commit, committer *
}
}
return &CommitVerification{
return &ObjectVerification{
CommittingUser: committer,
Verified: false,
Reason: NoKeyFound,
}
}
func verifySSHCommitVerification(sig, payload string, k *PublicKey, committer, signer *user_model.User, email string) *CommitVerification {
func verifySSHObjectVerification(sig, payload string, k *PublicKey, committer, signer *user_model.User, email string) *ObjectVerification {
if err := sshsig.Verify(bytes.NewBuffer([]byte(payload)), []byte(sig), []byte(k.Content), "git"); err != nil {
return nil
}
return &CommitVerification{ // Everything is ok
return &ObjectVerification{ // Everything is ok
CommittingUser: committer,
Verified: true,
Reason: fmt.Sprintf("%s / %s", signer.Name, k.Fingerprint),

18
models/asymkey/ssh_key_commit_verification_test.go → models/asymkey/ssh_key_object_verification_test.go
View file

@ -22,7 +22,8 @@ func TestParseCommitWithSSHSignature(t *testing.T) {
sshKey := unittest.AssertExistsAndLoadBean(t, &PublicKey{ID: 1000, OwnerID: 2})
t.Run("No commiter", func(t *testing.T) {
commitVerification := ParseCommitWithSSHSignature(db.DefaultContext, &git.Commit{}, &user_model.User{})
o := commitToGitObject(&git.Commit{})
commitVerification := ParseObjectWithSSHSignature(db.DefaultContext, &o, &user_model.User{})
assert.False(t, commitVerification.Verified)
assert.Equal(t, NoKeyFound, commitVerification.Reason)
})
@ -30,7 +31,8 @@ func TestParseCommitWithSSHSignature(t *testing.T) {
t.Run("Commiter without keys", func(t *testing.T) {
user := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 1})
commitVerification := ParseCommitWithSSHSignature(db.DefaultContext, &git.Commit{Committer: &git.Signature{Email: user.Email}}, user)
o := commitToGitObject(&git.Commit{Committer: &git.Signature{Email: user.Email}})
commitVerification := ParseObjectWithSSHSignature(db.DefaultContext, &o, user)
assert.False(t, commitVerification.Verified)
assert.Equal(t, NoKeyFound, commitVerification.Reason)
})
@ -57,7 +59,8 @@ AAAAQIMufOuSjZeDUujrkVK4sl7ICa0WwEftas8UAYxx0Thdkiw2qWjR1U1PKfTLm16/w8
`,
},
}
commitVerification := ParseCommitWithSSHSignature(db.DefaultContext, gitCommit, user2)
o := commitToGitObject(gitCommit)
commitVerification := ParseObjectWithSSHSignature(db.DefaultContext, &o, user2)
assert.False(t, commitVerification.Verified)
assert.Equal(t, NoKeyFound, commitVerification.Reason)
})
@ -79,7 +82,8 @@ Add content
},
}
commitVerification := ParseCommitWithSSHSignature(db.DefaultContext, gitCommit, user2)
o := commitToGitObject(gitCommit)
commitVerification := ParseObjectWithSSHSignature(db.DefaultContext, &o, user2)
assert.False(t, commitVerification.Verified)
assert.Equal(t, NoKeyFound, commitVerification.Reason)
})
@ -107,7 +111,8 @@ fs9cMpZVM9BfIKNUSO8QY=
},
}
commitVerification := ParseCommitWithSSHSignature(db.DefaultContext, gitCommit, user2)
o := commitToGitObject(gitCommit)
commitVerification := ParseObjectWithSSHSignature(db.DefaultContext, &o, user2)
assert.True(t, commitVerification.Verified)
assert.Equal(t, "user2 / SHA256:TKfwbZMR7e9OnlV2l1prfah1TXH8CmqR0PvFEXVCXA4", commitVerification.Reason)
assert.Equal(t, sshKey, commitVerification.SigningSSHKey)
@ -138,7 +143,8 @@ muPLbvEduU+Ze/1Ol1pgk=
},
}
commitVerification := ParseCommitWithSSHSignature(db.DefaultContext, gitCommit, user2)
o := commitToGitObject(gitCommit)
commitVerification := ParseObjectWithSSHSignature(db.DefaultContext, &o, user2)
assert.True(t, commitVerification.Verified)
assert.Equal(t, "user2 / SHA256:TKfwbZMR7e9OnlV2l1prfah1TXH8CmqR0PvFEXVCXA4", commitVerification.Reason)
assert.Equal(t, sshKey, commitVerification.SigningSSHKey)

2
modules/gitgraph/graph_models.go
View file

@ -238,7 +238,7 @@ func newRefsFromRefNames(refNames []byte) []git.Reference {
type Commit struct {
Commit *git.Commit
User *user_model.User
Verification *asymkey_model.CommitVerification
Verification *asymkey_model.ObjectVerification
Status *git_model.CommitStatus
Flow int64
Row int