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-rw-r--r--auth.c96
1 files changed, 2 insertions, 94 deletions
diff --git a/auth.c b/auth.c
index ca450f4e4..47c27773c 100644
--- a/auth.c
+++ b/auth.c
@@ -399,7 +399,8 @@ auth_root_allowed(struct ssh *ssh, const char *method)
399 case PERMIT_NO_PASSWD: 399 case PERMIT_NO_PASSWD:
400 if (strcmp(method, "publickey") == 0 || 400 if (strcmp(method, "publickey") == 0 ||
401 strcmp(method, "hostbased") == 0 || 401 strcmp(method, "hostbased") == 0 ||
402 strcmp(method, "gssapi-with-mic") == 0) 402 strcmp(method, "gssapi-with-mic") == 0 ||
403 strcmp(method, "gssapi-keyex") == 0)
403 return 1; 404 return 1;
404 break; 405 break;
405 case PERMIT_FORCED_ONLY: 406 case PERMIT_FORCED_ONLY:
@@ -724,99 +725,6 @@ fakepw(void)
724} 725}
725 726
726/* 727/*
727 * Returns the remote DNS hostname as a string. The returned string must not
728 * be freed. NB. this will usually trigger a DNS query the first time it is
729 * called.
730 * This function does additional checks on the hostname to mitigate some
731 * attacks on legacy rhosts-style authentication.
732 * XXX is RhostsRSAAuthentication vulnerable to these?
733 * XXX Can we remove these checks? (or if not, remove RhostsRSAAuthentication?)
734 */
735
736static char *
737remote_hostname(struct ssh *ssh)
738{
739 struct sockaddr_storage from;
740 socklen_t fromlen;
741 struct addrinfo hints, *ai, *aitop;
742 char name[NI_MAXHOST], ntop2[NI_MAXHOST];
743 const char *ntop = ssh_remote_ipaddr(ssh);
744
745 /* Get IP address of client. */
746 fromlen = sizeof(from);
747 memset(&from, 0, sizeof(from));
748 if (getpeername(ssh_packet_get_connection_in(ssh),
749 (struct sockaddr *)&from, &fromlen) == -1) {
750 debug("getpeername failed: %.100s", strerror(errno));
751 return strdup(ntop);
752 }
753
754 ipv64_normalise_mapped(&from, &fromlen);
755 if (from.ss_family == AF_INET6)
756 fromlen = sizeof(struct sockaddr_in6);
757
758 debug3("Trying to reverse map address %.100s.", ntop);
759 /* Map the IP address to a host name. */
760 if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
761 NULL, 0, NI_NAMEREQD) != 0) {
762 /* Host name not found. Use ip address. */
763 return strdup(ntop);
764 }
765
766 /*
767 * if reverse lookup result looks like a numeric hostname,
768 * someone is trying to trick us by PTR record like following:
769 * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5
770 */
771 memset(&hints, 0, sizeof(hints));
772 hints.ai_socktype = SOCK_DGRAM; /*dummy*/
773 hints.ai_flags = AI_NUMERICHOST;
774 if (getaddrinfo(name, NULL, &hints, &ai) == 0) {
775 logit("Nasty PTR record \"%s\" is set up for %s, ignoring",
776 name, ntop);
777 freeaddrinfo(ai);
778 return strdup(ntop);
779 }
780
781 /* Names are stored in lowercase. */
782 lowercase(name);
783
784 /*
785 * Map it back to an IP address and check that the given
786 * address actually is an address of this host. This is
787 * necessary because anyone with access to a name server can
788 * define arbitrary names for an IP address. Mapping from
789 * name to IP address can be trusted better (but can still be
790 * fooled if the intruder has access to the name server of
791 * the domain).
792 */
793 memset(&hints, 0, sizeof(hints));
794 hints.ai_family = from.ss_family;
795 hints.ai_socktype = SOCK_STREAM;
796 if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
797 logit("reverse mapping checking getaddrinfo for %.700s "
798 "[%s] failed.", name, ntop);
799 return strdup(ntop);
800 }
801 /* Look for the address from the list of addresses. */
802 for (ai = aitop; ai; ai = ai->ai_next) {
803 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
804 sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
805 (strcmp(ntop, ntop2) == 0))
806 break;
807 }
808 freeaddrinfo(aitop);
809 /* If we reached the end of the list, the address was not there. */
810 if (ai == NULL) {
811 /* Address not found for the host name. */
812 logit("Address %.100s maps to %.600s, but this does not "
813 "map back to the address.", ntop, name);
814 return strdup(ntop);
815 }
816 return strdup(name);
817}
818
819/*
820 * Return the canonical name of the host in the other side of the current 728 * Return the canonical name of the host in the other side of the current
821 * connection. The host name is cached, so it is efficient to call this 729 * connection. The host name is cached, so it is efficient to call this
822 * several times. 730 * several times.