On Mon, Dec 18, 2023 at 04:42:09PM +0000, Guilherme Janczak wrote:
> On Mon, Dec 18, 2023 at 07:31:37AM +0100, Otto Moerbeek wrote:
> > On Sun, Dec 17, 2023 at 05:37:50PM +0100, Otto Moerbeek wrote:
> >
> > > On Fri, Dec 15, 2023 at 02:54:19PM +0100, Otto Moerbeek wrote:
> > >
> > > > On Sun, Dec 10, 2023 at 09:57:08AM +0100, Otto Moerbeek wrote:
> > > >
> > > > > On Fri, Dec 01, 2023 at 09:18:32PM +0000,
> > > > > [email protected] wrote:
> > > > >
> > > > > > >Synopsis: Repeated NTP peers in OpenNTPD
> > > > > > >Category: user
> > > > > > >Environment:
> > > > > > System : OpenBSD 7.4
> > > > > > Details : OpenBSD 7.4 (GENERIC.MP) #0: Sun Oct 22 12:13:42
> > > > > > MDT 2023
> > > > > >
> > > > > > [email protected]:/usr/src/sys/arch/amd64/compile/GENERIC.MP
> > > > > >
> > > > > > Architecture: OpenBSD.amd64
> > > > > > Machine : amd64
> > > > > > >Description:
> > > > > > If the same address/domain is specified multiple times in
> > > > > > OpenNTPD's configuration file, or if multiple domains resolve
> > > > > > to the same IP address, OpenNTPD will treat the same IP address
> > > > > > as if it was multiple peers.
> > > > > > >How-To-Repeat:
> > > > > > This can be tested by appending `server 127.0.0.1` multiple
> > > > > > times to the configuration file.
> > > > > >
> > > > > > Alternatively, assuming a default OpenNTPD configuration file
> > > > > > from OpenBSD 7.4, the following entries can be added to
> > > > > > /etc/hosts:
> > > > > > 127.0.0.1 time.cloudflare.com
> > > > > > 127.0.0.1 pool.ntp.org
> > > > > >
> > > > > > I noticed this bug using the default 7.4 configuration file. It
> > > > > > can happen because time.cloudflare.com is part of pool.ntp.org:
> > > > > > https://www.ntppool.org/scores/162.159.200.1
> > > > > > https://www.ntppool.org/scores/162.159.200.123
> > > > > > >Fix:
> > > > > > Removing the `server time.cloudflare.com` line from the
> > > > > > configuration file is a simple fix the user can make, but
> > > > > > OpenNTPD should check if an IP address it tries to add to the
> > > > > > list of peers is already a peer, and ignore it if so. If a
> > > > > > server is added with the `server` (not `servers`) keyword in the
> > > > > > configuration file, OpenNTPD should try the next IP the domain
> > > > > > resolves to if applicable.
> > > > > >
> > > > >
> > > > > Thanks for the report, I'll take a look.
> > > > >
> > > > > -Otto
> > > > >
> > > >
> > > > Due to verious reasons this is all a bit complicated, I did not find a
> > > > nice solution yet. Some patience required.
> > > >
> > > > -Otto
> > > >
> > >
> > > Found some more time. Try this. The approach is: we assume the
> > > addresses of a pool (from the "servers" keyword) vary over time. So if
> > > one of the pool addresses is in the address list of a peer ("server")
> > > we skip it ad try to re-resolve the pool, lookin for a new address, as
> > > we already did earlier when a pool member doe snot respond.
> > >
> > > I decided to not implement "the move to abother address of the list"
> > > in the "server" case. The address logic is already complex enough.
> > >
> > > -Otto
> > >
> > > Index: client.c
> > > ===================================================================
> > > RCS file: /home/cvs/src/usr.sbin/ntpd/client.c,v
> > > diff -u -p -r1.117 client.c
> > > --- client.c 24 Mar 2022 07:37:19 -0000 1.117
> > > +++ client.c 17 Dec 2023 09:13:16 -0000
> > > @@ -108,6 +108,7 @@ client_nextaddr(struct ntp_peer *p)
> > > return (-1);
> > >
> > > if (p->addr_head.a == NULL) {
> > > + log_debug("kicking query for %s", p->addr_head.name);
> > > priv_dns(IMSG_HOST_DNS, p->addr_head.name, p->id);
> > > p->state = STATE_DNS_INPROGRESS;
> > > return (-1);
> > > @@ -145,7 +146,15 @@ client_query(struct ntp_peer *p)
> > > }
> > >
> > > if (p->state < STATE_DNS_DONE || p->addr == NULL)
> > > - return (-1);
> > > + return (0);
> > > +
> > > + /* if we're a pool member and a peer has taken our address, signal */
> > > + if (p->addr_head.pool != 0 && addr_already_used(&p->addr->ss)) {
> > > + log_debug("pool addr %s used by peer, will reresolve pool",
> > > + log_sockaddr((struct sockaddr *)&p->addr->ss));
> > > + p->senderrors++;
> > > + return (0);
> > > + }
> > >
> > > if (p->query.fd == -1) {
> > > struct sockaddr *sa = (struct sockaddr *)&p->addr->ss;
> > > Index: ntp.c
> > > ===================================================================
> > > RCS file: /home/cvs/src/usr.sbin/ntpd/ntp.c,v
> > > diff -u -p -r1.171 ntp.c
> > > --- ntp.c 6 Dec 2023 15:51:53 -0000 1.171
> > > +++ ntp.c 17 Dec 2023 09:13:16 -0000
> > > @@ -54,8 +54,6 @@ int ntp_dispatch_imsg(void);
> > > int ntp_dispatch_imsg_dns(void);
> > > void peer_add(struct ntp_peer *);
> > > void peer_remove(struct ntp_peer *);
> > > -int inpool(struct sockaddr_storage *,
> > > - struct sockaddr_storage[MAX_SERVERS_DNS], size_t);
> > >
> > > void
> > > ntp_sighdlr(int sig)
> > > @@ -524,23 +522,52 @@ ntp_dispatch_imsg(void)
> > > return (0);
> > > }
> > >
> > > -int
> > > +static int
> > > +addr_equal(struct sockaddr_storage *a, struct sockaddr_storage *b)
> > > +{
> > > + if (a->ss_family != b->ss_family)
> > > + return 0;
> > > + if (a->ss_family == AF_INET) {
> > > + if (((struct sockaddr_in *)a)->sin_addr.s_addr ==
> > > + ((struct sockaddr_in *)b)->sin_addr.s_addr)
> > > + return 1;
> > > + } else if (memcmp(&((struct sockaddr_in6 *)a)->sin6_addr,
> > > + &((struct sockaddr_in6 *)b)->sin6_addr,
> > > + sizeof(struct sockaddr_in6)) == 0) {
> > > + return 1;
> > > + }
> > > + return 0;
> > > +}
> > > +
> > > +static int
> > > inpool(struct sockaddr_storage *a,
> > > struct sockaddr_storage old[MAX_SERVERS_DNS], size_t n)
> > > {
> > > size_t i;
> > >
> > > for (i = 0; i < n; i++) {
> > > - if (a->ss_family != old[i].ss_family)
> > > + if (addr_equal(a, &old[i]))
> > > + return 1;
> > > + }
> > > + return 0;
> > > +}
> > > +
> > > +/* check to see af an address is already listed by a "server" peer
> > > + in that case, it does not get added to a pool */
> > > +int
> > > +addr_already_used(struct sockaddr_storage *a)
> > > +{
> > > + struct ntp_peer *peer;
> > > + struct ntp_addr *addr;
> > > +
> > > + TAILQ_FOREACH(peer, &conf->ntp_peers, entry) {
> > > + if (peer->addr_head.pool != 0)
> > > continue;
> > > - if (a->ss_family == AF_INET) {
> > > - if (((struct sockaddr_in *)a)->sin_addr.s_addr ==
> > > - ((struct sockaddr_in *)&old[i])->sin_addr.s_addr)
> > > + addr = peer->addr_head.a;
> > > + while (addr != NULL) {
> > > + if (addr_equal(a, &addr->ss))
> > > return 1;
> > > - } else if (memcmp(&((struct sockaddr_in6 *)a)->sin6_addr,
> > > - &((struct sockaddr_in6 *)&old[i])->sin6_addr,
> > > - sizeof(struct sockaddr_in6)) == 0) {
> > > - return 1;
> > > + addr = addr->next;
> > > }
> > > }
> > > return 0;
> > > @@ -628,8 +655,11 @@ ntp_dispatch_imsg_dns(void)
> > > free(h);
> > > continue;
> > > }
> > > - if (inpool(&h->ss, existing,
> > > - n)) {
> > > + if (addr_already_used(&h->ss) ||
> > > + inpool(&h->ss, existing, n)) {
> > > + log_debug("skipping address %s
> > > for %s",
> > > + log_sockaddr((struct
> > > sockaddr *)
> > > + &h->ss),
> > > peer->addr_head.name);
> > > free(h);
> > > continue;
> > > }
> > > @@ -660,8 +690,11 @@ ntp_dispatch_imsg_dns(void)
> > > }
> > > if (dlen != 0)
> > > fatalx("IMSG_HOST_DNS: dlen != 0");
> > > - if (peer->addr_head.pool)
> > > - peer_remove(peer);
> > > + if (peer->addr_head.pool) {
> > > + if (peercount > addrcount)
> > > + peer_remove(peer);
> > > + peer->state = STATE_NONE;
> > > + }
> > > else
> > > client_addr_init(peer);
> > > break;
> > > Index: ntpd.h
> > > ===================================================================
> > > RCS file: /home/cvs/src/usr.sbin/ntpd/ntpd.h,v
> > > diff -u -p -r1.152 ntpd.h
> > > --- ntpd.h 27 Nov 2022 13:19:00 -0000 1.152
> > > +++ ntpd.h 17 Dec 2023 09:13:16 -0000
> > > @@ -371,6 +371,7 @@ int server_dispatch(int, struct ntpd_con
> > > int client_peer_init(struct ntp_peer *);
> > > int client_addr_init(struct ntp_peer *);
> > > int client_nextaddr(struct ntp_peer *);
> > > +int addr_already_used(struct sockaddr_storage *);
> > > int client_query(struct ntp_peer *);
> > > int client_dispatch(struct ntp_peer *, u_int8_t, u_int8_t);
> > > void client_log_error(struct ntp_peer *, const char *, int);
> > >
> >
> > Previous diff had a write after free.
> >
> > -Otto
> >
> > Index: client.c
> > ===================================================================
> > RCS file: /home/cvs/src/usr.sbin/ntpd/client.c,v
> > diff -u -p -r1.117 client.c
> > --- client.c 24 Mar 2022 07:37:19 -0000 1.117
> > +++ client.c 18 Dec 2023 06:20:13 -0000
> > @@ -108,6 +108,7 @@ client_nextaddr(struct ntp_peer *p)
> > return (-1);
> >
> > if (p->addr_head.a == NULL) {
> > + log_debug("kicking query for %s", p->addr_head.name);
> > priv_dns(IMSG_HOST_DNS, p->addr_head.name, p->id);
> > p->state = STATE_DNS_INPROGRESS;
> > return (-1);
> > @@ -145,7 +146,15 @@ client_query(struct ntp_peer *p)
> > }
> >
> > if (p->state < STATE_DNS_DONE || p->addr == NULL)
> > - return (-1);
> > + return (0);
> > +
> > + /* if we're a pool member and a peer has taken our address, signal */
> > + if (p->addr_head.pool != 0 && addr_already_used(&p->addr->ss)) {
> > + log_debug("pool addr %s used by peer, will reresolve pool",
> > + log_sockaddr((struct sockaddr *)&p->addr->ss));
> > + p->senderrors++;
> > + return (0);
> > + }
> >
> > if (p->query.fd == -1) {
> > struct sockaddr *sa = (struct sockaddr *)&p->addr->ss;
> > Index: ntp.c
> > ===================================================================
> > RCS file: /home/cvs/src/usr.sbin/ntpd/ntp.c,v
> > diff -u -p -r1.171 ntp.c
> > --- ntp.c 6 Dec 2023 15:51:53 -0000 1.171
> > +++ ntp.c 18 Dec 2023 06:20:13 -0000
> > @@ -54,8 +54,6 @@ int ntp_dispatch_imsg(void);
> > int ntp_dispatch_imsg_dns(void);
> > void peer_add(struct ntp_peer *);
> > void peer_remove(struct ntp_peer *);
> > -int inpool(struct sockaddr_storage *,
> > - struct sockaddr_storage[MAX_SERVERS_DNS], size_t);
> >
> > void
> > ntp_sighdlr(int sig)
> > @@ -524,23 +522,52 @@ ntp_dispatch_imsg(void)
> > return (0);
> > }
> >
> > -int
> > +static int
> > +addr_equal(struct sockaddr_storage *a, struct sockaddr_storage *b)
> > +{
> > + if (a->ss_family != b->ss_family)
> > + return 0;
> > + if (a->ss_family == AF_INET) {
> > + if (((struct sockaddr_in *)a)->sin_addr.s_addr ==
> > + ((struct sockaddr_in *)b)->sin_addr.s_addr)
> > + return 1;
> > + } else if (memcmp(&((struct sockaddr_in6 *)a)->sin6_addr,
> > + &((struct sockaddr_in6 *)b)->sin6_addr,
> > + sizeof(struct sockaddr_in6)) == 0) {
> > + return 1;
> > + }
> > + return 0;
> > +}
> > +
> > +static int
> > inpool(struct sockaddr_storage *a,
> > struct sockaddr_storage old[MAX_SERVERS_DNS], size_t n)
> > {
> > size_t i;
> >
> > for (i = 0; i < n; i++) {
> > - if (a->ss_family != old[i].ss_family)
> > + if (addr_equal(a, &old[i]))
> > + return 1;
> > + }
> > + return 0;
> > +}
> > +
> > +/* check to see af an address is already listed by a "server" peer
> > + in that case, it does not get added to a pool */
> > +int
> > +addr_already_used(struct sockaddr_storage *a)
> > +{
> > + struct ntp_peer *peer;
> > + struct ntp_addr *addr;
> > +
> > + TAILQ_FOREACH(peer, &conf->ntp_peers, entry) {
> > + if (peer->addr_head.pool != 0)
> > continue;
> > - if (a->ss_family == AF_INET) {
> > - if (((struct sockaddr_in *)a)->sin_addr.s_addr ==
> > - ((struct sockaddr_in *)&old[i])->sin_addr.s_addr)
> > + addr = peer->addr_head.a;
> > + while (addr != NULL) {
> > + if (addr_equal(a, &addr->ss))
> > return 1;
> > - } else if (memcmp(&((struct sockaddr_in6 *)a)->sin6_addr,
> > - &((struct sockaddr_in6 *)&old[i])->sin6_addr,
> > - sizeof(struct sockaddr_in6)) == 0) {
> > - return 1;
> > + addr = addr->next;
> > }
> > }
> > return 0;
> > @@ -628,8 +655,11 @@ ntp_dispatch_imsg_dns(void)
> > free(h);
> > continue;
> > }
> > - if (inpool(&h->ss, existing,
> > - n)) {
> > + if (addr_already_used(&h->ss) ||
> > + inpool(&h->ss, existing, n)) {
> > + log_debug("skipping address %s
> > for %s",
> > + log_sockaddr((struct
> > sockaddr *)
> > + &h->ss),
> > peer->addr_head.name);
> > free(h);
> > continue;
> > }
> > @@ -660,8 +690,12 @@ ntp_dispatch_imsg_dns(void)
> > }
> > if (dlen != 0)
> > fatalx("IMSG_HOST_DNS: dlen != 0");
> > - if (peer->addr_head.pool)
> > - peer_remove(peer);
> > + if (peer->addr_head.pool) {
> > + if (peercount > addrcount)
> > + peer_remove(peer);
> > + else
> > + peer->state = STATE_NONE;
> > + }
> > else
> > client_addr_init(peer);
> > break;
> > Index: ntpd.h
> > ===================================================================
> > RCS file: /home/cvs/src/usr.sbin/ntpd/ntpd.h,v
> > diff -u -p -r1.152 ntpd.h
> > --- ntpd.h 27 Nov 2022 13:19:00 -0000 1.152
> > +++ ntpd.h 18 Dec 2023 06:20:13 -0000
> > @@ -371,6 +371,7 @@ int server_dispatch(int, struct ntpd_con
> > int client_peer_init(struct ntp_peer *);
> > int client_addr_init(struct ntp_peer *);
> > int client_nextaddr(struct ntp_peer *);
> > +int addr_already_used(struct sockaddr_storage *);
> > int client_query(struct ntp_peer *);
> > int client_dispatch(struct ntp_peer *, u_int8_t, u_int8_t);
> > void client_log_error(struct ntp_peer *, const char *, int);
> >
>
> That solves the bug with the default config file. I can see how a
> repeated peer is marked as "not resolved," and how ntpd tries to find a
> new unique IP every poll interval, but as you mentioned, it only checks
> if a pool address matches a peer address.
>
> Testing with this config file:
> ```
> servers br.pool.ntp.org
> servers time.cloudflare.com
>
> constraint from "9.9.9.9" # quad9 v4 without DNS
> constraint from "2620:fe::fe" # quad9 v6 without DNS
> constraints from "www.google.com" # intentionally not 8.8.8.8
> ```
>
> I still see repeated peers (162.159.200.1 and 162.159.200.123):
> ```
> $ ntpctl -s all
> 8/8 peers valid, constraint offset -2s, clock unsynced
>
> peer
> wt tl st next poll offset delay jitter
> 162.159.200.1 from pool br.pool.ntp.org
> 1 10 3 28s 33s 0.147ms 9.531ms 0.246ms
> 168.181.125.82 from pool br.pool.ntp.org
> 1 10 2 27s 34s 11.375ms 38.489ms 0.436ms
> 162.159.200.123 from pool br.pool.ntp.org
> 1 10 3 6s 34s -0.585ms 11.994ms 0.351ms
> 138.99.160.244 from pool br.pool.ntp.org
> 1 10 3 1s 32s 1.017ms 18.735ms 1.252ms
> 2606:4700:f1::123 from pool time.cloudflare.com
> 1 10 3 30s 34s 1.029ms 14.623ms 3.945ms
> 2606:4700:f1::1 from pool time.cloudflare.com
> 1 10 3 30s 33s -0.617ms 11.538ms 0.381ms
> 162.159.200.1 from pool time.cloudflare.com
> 1 10 3 2s 32s -1.867ms 21.497ms 6.333ms
> 162.159.200.123 from pool time.cloudflare.com
> 1 10 3 5s 32s 2.403ms 14.003ms 6.336ms
> ```
Yes, this is a "known" limitation of the approach. Pools are not
cross-checked for duplicates. I might consider that, I have to think if
there are drawbacks to that.
> Trying multiple pool.ntp.org regions helps find one currently serving a
> time.cloudflare.com address.
>
> Also, I can't seem to get the debug messages. They don't show up with
> `ntpd -v` or and `ntpd -dv`.
Use ntpd -dvv
-Otto
