diff options
Diffstat (limited to 'ntpd/ntp_signd.c')
| -rw-r--r-- | ntpd/ntp_signd.c | 239 |
1 files changed, 239 insertions, 0 deletions
diff --git a/ntpd/ntp_signd.c b/ntpd/ntp_signd.c new file mode 100644 index 000000000000..3beb03be5a69 --- /dev/null +++ b/ntpd/ntp_signd.c @@ -0,0 +1,239 @@ +/* Copyright 2008, Red Hat, Inc. + Copyright 2008, Andrew Tridgell. + Licenced under the same terms as NTP itself. + */ +#ifdef HAVE_CONFIG_H +#include <config.h> +#endif + +#ifdef HAVE_NTP_SIGND + +#include "ntpd.h" +#include "ntp_io.h" +#include "ntp_stdlib.h" +#include "ntp_unixtime.h" +#include "ntp_control.h" +#include "ntp_string.h" + +#include <stdio.h> +#include <stddef.h> +#ifdef HAVE_LIBSCF_H +#include <libscf.h> +#include <unistd.h> +#endif /* HAVE_LIBSCF_H */ + +#include <sys/un.h> + +/* socket routines by tridge - from junkcode.samba.org */ + +/* + connect to a unix domain socket +*/ +static int +ux_socket_connect(const char *name) +{ + int fd; + struct sockaddr_un addr; + if (!name) { + return -1; + } + + memset(&addr, 0, sizeof(addr)); + addr.sun_family = AF_UNIX; + strncpy(addr.sun_path, name, sizeof(addr.sun_path)); + + fd = socket(AF_UNIX, SOCK_STREAM, 0); + if (fd == -1) { + return -1; + } + + if (connect(fd, (struct sockaddr *)&addr, sizeof(addr)) == -1) { + close(fd); + return -1; + } + + return fd; +} + + +/* + keep writing until its all sent +*/ +static int +write_all(int fd, const void *buf, size_t len) +{ + size_t total = 0; + while (len) { + int n = write(fd, buf, len); + if (n <= 0) return total; + buf = n + (char *)buf; + len -= n; + total += n; + } + return total; +} + +/* + keep reading until its all read +*/ +static int +read_all(int fd, void *buf, size_t len) +{ + size_t total = 0; + while (len) { + int n = read(fd, buf, len); + if (n <= 0) return total; + buf = n + (char *)buf; + len -= n; + total += n; + } + return total; +} + +/* + send a packet in length prefix format +*/ +static int +send_packet(int fd, const char *buf, uint32_t len) +{ + uint32_t net_len = htonl(len); + if (write_all(fd, &net_len, sizeof(net_len)) != sizeof(net_len)) return -1; + if (write_all(fd, buf, len) != len) return -1; + return 0; +} + +/* + receive a packet in length prefix format +*/ +static int +recv_packet(int fd, char **buf, uint32_t *len) +{ + if (read_all(fd, len, sizeof(*len)) != sizeof(*len)) return -1; + *len = ntohl(*len); + (*buf) = emalloc(*len); + if (read_all(fd, *buf, *len) != *len) { + free(*buf); + return -1; + } + return 0; +} + +void +send_via_ntp_signd( + struct recvbuf *rbufp, /* receive packet pointer */ + int xmode, + keyid_t xkeyid, + int flags, + struct pkt *xpkt + ) +{ + + /* We are here because it was detected that the client + * sent an all-zero signature, and we therefore know + * it's windows trying to talk to an AD server + * + * Because we don't want to dive into Samba's secrets + * database just to find the long-term kerberos key + * that is re-used as the NTP key, we instead hand the + * packet over to Samba to sign, and return to us. + * + * The signing method Samba will use is described by + * Microsoft in MS-SNTP, found here: + * http://msdn.microsoft.com/en-us/library/cc212930.aspx + */ + + int fd, sendlen; + struct samba_key_in { + uint32_t version; + uint32_t op; + uint32_t packet_id; + uint32_t key_id_le; + struct pkt pkt; + } samba_pkt; + + struct samba_key_out { + uint32_t version; + uint32_t op; + uint32_t packet_id; + struct pkt pkt; + } samba_reply; + + char full_socket[256]; + + char *reply = NULL; + uint32_t reply_len; + + memset(&samba_pkt, 0, sizeof(samba_pkt)); + samba_pkt.op = 0; /* Sign message */ + /* This will be echoed into the reply - a different + * impelementation might want multiple packets + * awaiting signing */ + + samba_pkt.packet_id = 1; + + /* Swap the byte order back - it's actually little + * endian on the wire, but it was read above as + * network byte order */ + samba_pkt.key_id_le = htonl(xkeyid); + samba_pkt.pkt = *xpkt; + + snprintf(full_socket, sizeof(full_socket), "%s/socket", ntp_signd_socket); + + fd = ux_socket_connect(full_socket); + /* Only continue with this if we can talk to Samba */ + if (fd != -1) { + /* Send old packet to Samba, expect response */ + /* Packet to Samba is quite simple: + All values BIG endian except key ID as noted + [packet size as BE] - 4 bytes + [protocol version (0)] - 4 bytes + [packet ID] - 4 bytes + [operation (sign message=0)] - 4 bytes + [key id] - LITTLE endian (as on wire) - 4 bytes + [message to sign] - as marshalled, without signature + */ + + if (send_packet(fd, (char *)&samba_pkt, offsetof(struct samba_key_in, pkt) + LEN_PKT_NOMAC) != 0) { + /* Huh? could not talk to Samba... */ + close(fd); + return; + } + + if (recv_packet(fd, &reply, &reply_len) != 0) { + if (reply) { + free(reply); + } + close(fd); + return; + } + /* Return packet is also simple: + [packet size] - network byte order - 4 bytes + [protocol version (0)] network byte order - - 4 bytes + [operation (signed success=3, failure=4)] network byte order - - 4 byte + (optional) [signed message] - as provided before, with signature appended + */ + + if (reply_len <= sizeof(samba_reply)) { + memcpy(&samba_reply, reply, reply_len); + if (ntohl(samba_reply.op) == 3 && reply_len > offsetof(struct samba_key_out, pkt)) { + sendlen = reply_len - offsetof(struct samba_key_out, pkt); + xpkt = &samba_reply.pkt; + sendpkt(&rbufp->recv_srcadr, rbufp->dstadr, 0, xpkt, sendlen); +#ifdef DEBUG + if (debug) + printf( + "transmit ntp_signd packet: at %ld %s->%s mode %d keyid %08x len %d\n", + current_time, ntoa(&rbufp->dstadr->sin), + ntoa(&rbufp->recv_srcadr), xmode, xkeyid, sendlen); +#endif + } + } + + if (reply) { + free(reply); + } + close(fd); + + } +} +#endif |