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Report permissions denied in internal SSH (#13953) 

This PR standardizes reporting of permission denied from the internal ssh.

Signed-off-by: Andrew Thornton <art27@cantab.net>

Co-authored-by: 6543 <6543@obermui.de>
This commit is contained in:
zeripath 2020-12-11 22:52:38 +00:00 committed by GitHub
parent 8e0548ed4a
commit e46a638e8f
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 14 additions and 5 deletions
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19
modules/ssh/ssh.go
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@ -135,6 +135,7 @@ func sessionHandler(session ssh.Session) {
func publicKeyHandler(ctx ssh.Context, key ssh.PublicKey) bool { func publicKeyHandler(ctx ssh.Context, key ssh.PublicKey) bool {
if ctx.User() != setting.SSH.BuiltinServerUser { if ctx.User() != setting.SSH.BuiltinServerUser {
log.Warn("Permission Denied: Invalid SSH username %s - must use %s for all git operations via ssh", ctx.User(), setting.SSH.BuiltinServerUser)
return false return false
} }
@ -145,17 +146,18 @@ func publicKeyHandler(ctx ssh.Context, key ssh.PublicKey) bool {
} }
// look for the exact principal // look for the exact principal
principalLoop:
for _, principal := range cert.ValidPrincipals { for _, principal := range cert.ValidPrincipals {
pkey, err := models.SearchPublicKeyByContentExact(principal) pkey, err := models.SearchPublicKeyByContentExact(principal)
if err != nil { if err != nil {
if models.IsErrKeyNotExist(err) {
log.Debug("Principal Rejected: Unknown Principal: %s", principal)
continue principalLoop
}
log.Error("SearchPublicKeyByContentExact: %v", err) log.Error("SearchPublicKeyByContentExact: %v", err)
return false return false
} }
if models.IsErrKeyNotExist(err) {
continue
}
c := &gossh.CertChecker{ c := &gossh.CertChecker{
IsUserAuthority: func(auth gossh.PublicKey) bool { IsUserAuthority: func(auth gossh.PublicKey) bool {
for _, k := range setting.SSH.TrustedUserCAKeysParsed { for _, k := range setting.SSH.TrustedUserCAKeysParsed {
@ -170,11 +172,14 @@ func publicKeyHandler(ctx ssh.Context, key ssh.PublicKey) bool {
// check the CA of the cert // check the CA of the cert
if !c.IsUserAuthority(cert.SignatureKey) { if !c.IsUserAuthority(cert.SignatureKey) {
return false log.Debug("Principal Rejected: Untrusted Authority Signature Fingerprint %s for Principal: %s", gossh.FingerprintSHA256(cert.SignatureKey), principal)
continue principalLoop
} }
// validate the cert for this principal // validate the cert for this principal
if err := c.CheckCert(principal, cert); err != nil { if err := c.CheckCert(principal, cert); err != nil {
// User is presenting an invalid cerficate - STOP any further processing
log.Error("Permission Denied: Invalid Certificate KeyID %s with Signature Fingerprint %s presented for Principal: %s", cert.KeyId, gossh.FingerprintSHA256(cert.SignatureKey), principal)
return false return false
} }
@ -186,6 +191,10 @@ func publicKeyHandler(ctx ssh.Context, key ssh.PublicKey) bool {
pkey, err := models.SearchPublicKeyByContent(strings.TrimSpace(string(gossh.MarshalAuthorizedKey(key)))) pkey, err := models.SearchPublicKeyByContent(strings.TrimSpace(string(gossh.MarshalAuthorizedKey(key))))
if err != nil { if err != nil {
if models.IsErrKeyNotExist(err) {
log.Warn("Permission Denied: Unknown public key : %s", gossh.FingerprintSHA256(key))
return false
}
log.Error("SearchPublicKeyByContent: %v Failed authentication attempt from %s", err, ctx.RemoteAddr()) log.Error("SearchPublicKeyByContent: %v Failed authentication attempt from %s", err, ctx.RemoteAddr())
return false return false
} }