When using sshd's -i option with stdio that is not a AF_INET/AF_INET6
socket, auth_get_canonical_hostname() returns "UNKNOWN" which is then
set as the value of PAM_RHOST, causing pam to try to do a reverse DNS
query of "UNKNOWN", which times out multiple times, causing a
substantial slowdown when logging in.
To fix this, let's only set PAM_RHOST if we're connected to a proper
socket in the first place.
---
auth-pam.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/auth-pam.c b/auth-pam.c
index b49d415e7..706b02420 100644
--- a/auth-pam.c
+++ b/auth-pam.c
@@ -735,7 +735,7 @@ sshpam_init(struct ssh *ssh, Authctxt *authctxt)
sshpam_laddr = get_local_ipaddr(
ssh_packet_get_connection_in(ssh));
}
- if (sshpam_rhost != NULL) {
+ if (sshpam_rhost != NULL && ssh_packet_connection_is_on_socket(ssh)) {
debug("PAM: setting PAM_RHOST to \"%s\"", sshpam_rhost);
sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST,
sshpam_rhost);
--
2.43.0